Catalysts

16 pages, 4090 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Confined Catalysis Involving a Palladium Complex and a Self-Assembled Capsule for the Dimerization of Vinyl Arenes and the Formation of Indane and Tribenzo–Pentaphene Derivatives

by Maxime Steinmetz and David Sémeril

Catalysts 2025, 15(6), 585; https://doi.org/10.3390/catal15060585 - 12 Jun 2025

Cited by 1 | Viewed by 1074

Abstract

The [PdCl₂(cod)] complex was encapsulated inside a self-assembled hexameric capsule obtained via a reaction of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible, ¹H NMR and DOSY spectroscopies). The latter [...] Read more.

The [PdCl₂(cod)] complex was encapsulated inside a self-assembled hexameric capsule obtained via a reaction of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible, ¹H NMR and DOSY spectroscopies). The latter proved effective in the dimerization of styrene derivatives under mild conditions, with a catalyst loading of 0.5 mol% at 60 °C. Electronically enriched vinyl arenes underwent cyclization of the catalytic products, leading to the quasi-quantitative formation of indanes from 4-tert-butylstyrene and 9-vinylanthracene. In the instance of 9-vinylanthracene, the rearrangement product is tribenzo–pentaphene, which is formed in 50% of conversions. Full article

(This article belongs to the Special Issue Sustainable Catalysis for Green Chemistry and Energy Transition)

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24 pages, 2822 KB

Open AccessFeature PaperEditor’s ChoiceReview

Green Pathways: Enhancing Amine Synthesis Using Deep Eutectic Solvents

by Andrés R. Alcántara and Gonzalo de Gonzalo

Catalysts 2025, 15(6), 586; https://doi.org/10.3390/catal15060586 - 12 Jun 2025

Cited by 1 | Viewed by 4369

Abstract

Deep eutectic solvents (DESs) have emerged as prominent, environmentally benign substitutes for traditional solvents and catalysts in organic synthesis, notably in the synthesis of amines, pivotal structures in many industrial sectors. Their distinctive physicochemical attributes—including negligible volatility, exceptional thermal stability, and adjustable polarity—render [...] Read more.

Deep eutectic solvents (DESs) have emerged as prominent, environmentally benign substitutes for traditional solvents and catalysts in organic synthesis, notably in the synthesis of amines, pivotal structures in many industrial sectors. Their distinctive physicochemical attributes—including negligible volatility, exceptional thermal stability, and adjustable polarity—render them particularly advantageous for facilitating a broad spectrum of amination reactions. DESs can serve dually as reaction media and as intrinsic catalytic systems, accelerating reaction kinetics without necessitating supplementary catalysts or severe reaction conditions. They are especially efficacious in processes such as reductive amination, transamination, and multicomponent transformations, often affording superior yields and streamlining product isolation. The extensive hydrogen-bonding network intrinsic to DESs is believed to mediate crucial mechanistic steps, frequently obviating the requirement for external additives. Moreover, DESs are recyclable and exhibit compatibility with a diverse array of substrates, encompassing bio-derived and pharmaceutical intermediates. Full article

(This article belongs to the Special Issue Feature Papers in Catalysis for Pharmaceuticals)

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15 pages, 3620 KB

Open AccessFeature PaperEditor’s ChoiceArticle

ZIF-L/PBA-Derived Self-Supporting Ni-Doped CoFeP Electrocatalysts for Bifunctional Water Splitting

by Lanqi Wang, Hui Ni, Jianing Yu, Jingyuan Zhang and Bin Zhao

Catalysts 2025, 15(6), 576; https://doi.org/10.3390/catal15060576 - 10 Jun 2025

Viewed by 1428

Abstract

In recent years, transition metal-based catalytic materials have garnered considerable attention, particularly those exhibiting high catalytic efficiency toward both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, a self-supporting ternary transition metal phosphide (CoFeNi_0.2P) with a [...] Read more.

In recent years, transition metal-based catalytic materials have garnered considerable attention, particularly those exhibiting high catalytic efficiency toward both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, a self-supporting ternary transition metal phosphide (CoFeNi_0.2P) with a hierarchical structure was synthesized using the Prussian blue analogue (PBA)/zeolitic imidazolate framework-L (ZIF-L) template. Benefiting from the hierarchical structure of the PBA/ZIF-L precursor and the electronic structure modulation induced by Ni doping, the resulting CoFeNi_0.2P demonstrates impressive bifunctional electrocatalytic activity. Specifically, in 1 M KOH electrolyte, the CoFeNi_0.2P catalyst requires an overpotential of only 88 mV to deliver 10 mA cm⁻² for the HER and 248 mV to achieve 50 mA cm⁻² for the OER. Moreover, it demonstrates satisfactory stability toward both the HER and OER. When integrated into a two-electrode electrolyzer, CoFeNi_0.2P enables a current density of 10 mA cm⁻² at a cell voltage of 1.59 V, maintaining robust performance for over 25 h. This study provides a feasible strategy for the rational design of hierarchical electrocatalysts for efficient overall water splitting. Full article

(This article belongs to the Special Issue Two-Dimensional (2D) Materials in Catalysis)

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33 pages, 2401 KB

Open AccessEditor’s ChoiceReview

Recent Advances in Enzyme Immobilization: The Role of Artificial Intelligence, Novel Nanomaterials, and Dynamic Carrier Systems

by Melesse Tadesse and Yun Liu

Catalysts 2025, 15(6), 571; https://doi.org/10.3390/catal15060571 - 9 Jun 2025

Cited by 8 | Viewed by 10856

Abstract

Enzymes, as nature’s precision biocatalysts, hold transformative potential across industrial, environmental, and biomedical sectors. However, their instability, solvent sensitivity, and limited reusability in their free form necessitate advanced immobilization strategies to enhance their robustness and scalability. This review critically examines cutting-edge advancements in [...] Read more.

Enzymes, as nature’s precision biocatalysts, hold transformative potential across industrial, environmental, and biomedical sectors. However, their instability, solvent sensitivity, and limited reusability in their free form necessitate advanced immobilization strategies to enhance their robustness and scalability. This review critically examines cutting-edge advancements in enzyme immobilization, focusing on the integration of artificial intelligence (AI), novel nanomaterials, and dynamic carrier systems to overcome the traditional limitations of mass transfer, enzyme leakage, and cost inefficiency. Key innovations such as metal–organic frameworks (MOFs), magnetic nanoparticles, self-healing hydrogels, and 3D-printed scaffolds are highlighted for their ability to optimize enzyme orientation, stability, and catalytic efficiency under extreme conditions. Moreover, AI-driven predictive modeling and machine learning emerge as pivotal tools for rationalizing nanomaterial synthesis, multi-enzyme cascade design, and toxicity assessment, while microfluidic systems enable precise biocatalyst fabrication. This review also explores emerging carrier-free strategies, including cross-linked enzyme aggregates (CLEAs) and DNA-directed immobilization, which minimize diffusion barriers and enhance substrate affinity. Despite progress, challenges persist in regards to eco-friendly nanomaterial production, industrial scalability, and real-world application viability. Future directions emphasize sustainable hybrid material design, AI-aided lifecycle assessments, and interdisciplinary synergies between synthetic biology, nanotechnology, and data analytics. By connecting laboratory innovation with industrial needs, this work provides a forward-thinking framework to harness immobilized enzymes for achieving global sustainability goals, particularly in bioremediation, bioenergy, and precision medicine. Full article

(This article belongs to the Section Biocatalysis)

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24 pages, 3128 KB

Open AccessEditor’s ChoiceReview

Biochar-Based Materials for Catalytic CO₂ Valorization

by Shahab Zomorodbakhsh, Lucas D. Dias, Mário J. F. Calvete, Andreia F. Peixoto, Rui M. B. Carrilho and Mariette M. Pereira

Catalysts 2025, 15(6), 568; https://doi.org/10.3390/catal15060568 - 8 Jun 2025

Viewed by 2641

Abstract

Biochar-based materials have gathered increasing attention as sustainable catalysts for carbon dioxide (CO₂) valorization, offering a green alternative to traditional metal-based systems. Produced from renewable biomass through pyrolysis, biochar possesses key features—such as high surface area, rich porosity and tunable surface [...] Read more.

Biochar-based materials have gathered increasing attention as sustainable catalysts for carbon dioxide (CO₂) valorization, offering a green alternative to traditional metal-based systems. Produced from renewable biomass through pyrolysis, biochar possesses key features—such as high surface area, rich porosity and tunable surface chemistry—that make it particularly suited for heterogeneous catalysis. This review highlights recent advances in the use of biochar-derived catalysts for key CO₂ conversion reactions, focusing on cycloaddition to epoxides, dry reforming of methane and catalytic biomass upgrading. Emphasis is given to the role of biochar’s origin and preparation methods, which critically influence its structure, surface functionality and catalytic performance. Feedstocks rich in mineral content or oxygenated groups, for instance, can enhance CO₂ activation and product selectivity. Furthermore, tailored modifications—such as doping with heteroatoms or supporting metal nanoparticles—further boost catalytic activity and stability by tuning acid–base behavior, while maintaining low toxicity and cost-effectiveness. Compared to conventional catalysts, biochar-based systems offer advantages in low cost, recyclability and resistance to deactivation. Challenges remain in standardizing production methods, controlling structural variability, minimizing metal leaching and scaling up. This review presents biochar as a versatile, renewable platform for CO₂ utilization, highlighting the importance of rational design, feedstock selection and functionalization strategies for developing efficient, sustainable catalytic systems, in line with green chemistry and circular economy principles. Full article

(This article belongs to the Special Issue Carbon-Based Catalysts to Address Environmental Challenges)

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23 pages, 1513 KB

Open AccessEditor’s ChoiceArticle

A New Serine Protease (AsKSP) with Fibrinolytic Potential Obtained from Aspergillus tamarii Kita UCP 1279: Biochemical, Cytotoxic and Hematological Evaluation

by José P. Martins Barbosa-Filho, Renata V. Silva Sobral, Viviane N. S. Alencar, Marllyn Marques Silva, Juanize M. Silva Batista, Galba Maria Campos-Takaki, Wendell W. C. Albuquerque, Romero M. P. Brandão-Costa, Ana Lúcia Figueiredo Porto, Ana C. L. Leite and Thiago Pajéu Nascimento

Catalysts 2025, 15(6), 561; https://doi.org/10.3390/catal15060561 - 5 Jun 2025

Viewed by 1205

Abstract

This study aimed to characterize and evaluate the fibrinolytic, thrombolytic, hematological, and toxicological aspects of a serine protease (AsKSP) from Aspergillus tamarii Kita UCP 1279. The enzyme was purified using a two-phase aqueous system and assessed for optimal pH (7.0) and temperature (50 °C), [...] Read more.

This study aimed to characterize and evaluate the fibrinolytic, thrombolytic, hematological, and toxicological aspects of a serine protease (AsKSP) from Aspergillus tamarii Kita UCP 1279. The enzyme was purified using a two-phase aqueous system and assessed for optimal pH (7.0) and temperature (50 °C), stability, and effects of metal ions, inhibitors, and surfactants. AsKSP exhibited stability for up to 120 min at 50 °C and 36 h at pH 7.0. Enzymatic activity was enhanced by Na⁺ and Zn²⁺ and non-ionic surfactants (Tween-80) but inhibited by Cu²⁺, Fe³⁺, Triton X-100, and SDS, reducing activity by up to 62.35%. The highest amidolytic activity was observed for the substrate N-succinyl-Gly–Gly–Phe-p-nitroanilide. SDS-PAGE analysis indicated an approximate molecular mass of 90 kDa. The enzyme showed fibrinolytic activity, degrading 38.81% of fibrin clots in vitro after 90 min, without affecting fibrinogen. Cytotoxicity assays indicated no toxicity (cell viability > 80%). Coagulation assays showed slight prolongation of prothrombin time (PT) and activated partial thromboplastin time (aPTT), with no effect on thrombin time. No red blood cell lysis was observed, and albumin increased enzymatic activity by 31.70%. These findings demonstrate that Aspergillus tamarii Kita UCP 1279 produces a fibrinolytic protease with potential for thrombus treatment, providing a promising foundation for drug development. Full article

(This article belongs to the Section Catalysis for Pharmaceuticals)

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24 pages, 3631 KB

Open AccessEditor’s ChoiceReview

A Review on Production of Ethylene Oxide from Epoxidation of Ethylene: Catalysis, Mechanism and Kinetics

by Mahammad Ali Saritala, Mohammed Muzammil, Mohammad R. Quddus, Shaikh Abdur Razzak and Mohammad M. Hossain

Catalysts 2025, 15(6), 560; https://doi.org/10.3390/catal15060560 - 4 Jun 2025

Viewed by 5840

Abstract

This review describes the different developments in the production of ethylene oxide (EO) by epoxidation of ethylene. EO is an important chemical intermediate for the manufacture of a variety of industrial and consumer products, such as ethylene glycol, plastics, and pharmaceuticals. The conventional [...] Read more.

This review describes the different developments in the production of ethylene oxide (EO) by epoxidation of ethylene. EO is an important chemical intermediate for the manufacture of a variety of industrial and consumer products, such as ethylene glycol, plastics, and pharmaceuticals. The conventional gas-phase epoxidation process using silver-based catalysts suffers from major drawbacks, including low selectivity and high carbon dioxide emissions. This review underlines emerging solutions for efficiency and sustainability improvement in EO production. Major developments in catalyst design, including novel silver-based hybrid nanostructures, Mn-N₄GP catalysts, and chemical looping epoxidation processes, are presented. It also discusses developments in reaction kinetics, including catalyst surface optimization and the use of dopants. The article also outlines catalyst deactivation challenges, cost, and scalability and describes future research directions on renewable feedstocks, reducing energy consumption and most importantly environmental impact. These innovations are oriented toward a more sustainable and economical route for large-scale manufacturing of ethylene oxide. Full article

(This article belongs to the Section Catalytic Reaction Engineering)

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24 pages, 9418 KB

Open AccessEditor’s ChoiceArticle

Exploring the Role of Non-Metal Doping in g-C₃N₄ for CO₂ Reduction: A DFT Investigation

by Wassana Mongkonkan, Kaito Takahashi, Yuwanda Injongkol, Nuttapon Yodsin, Supawadee Namuangruk and Siriporn Jungsuttiwong

Catalysts 2025, 15(6), 553; https://doi.org/10.3390/catal15060553 - 3 Jun 2025

Cited by 3 | Viewed by 1615

Abstract

The electrochemical reduction of CO₂ (CO₂RR) to valuable chemicals and fuels is a promising strategy for addressing environmental challenges. Graphitic carbon nitride (g-C₃N₄) is a promising electrocatalyst for CO₂ reduction. However, poor electron transfer and [...] Read more.

The electrochemical reduction of CO₂ (CO₂RR) to valuable chemicals and fuels is a promising strategy for addressing environmental challenges. Graphitic carbon nitride (g-C₃N₄) is a promising electrocatalyst for CO₂ reduction. However, poor electron transfer and low CO₂ affinity often limit its catalytic performance. In this study, we employ density functional theory (DFT) calculations to systematically investigate the effect of various non-metal dopants (B, P, O, and S) on the electronic structure and CO₂ adsorption properties of g-C₃N₄. Our results demonstrated that O-C₃N₄ preferentially catalyzes the formation of HCOOH with a low limiting potential of −0.12 V. Meanwhile, S-C₃N₄ efficiently promotes the generation of CH₂O, CH₃OH, and CH₄ at a limiting potential of −0.58 V, as well as CO at −0.77 V. These findings provide valuable insights toward the rational design of effective non-metal-doped g-C₃N₄ catalysts for efficient CO₂ conversion. Full article

(This article belongs to the Topic Electrocatalytic Advances for Sustainable Energy)

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14 pages, 2373 KB

Open AccessEditor’s ChoiceArticle

Isomeric Anthraquinone-Based Covalent Organic Frameworks for Boosting Photocatalytic Hydrogen Peroxide Generation

by Shengrong Yan, Songhu Shi, Wenhao Liu, Fang Duan, Shuanglong Lu and Mingqing Chen

Catalysts 2025, 15(6), 556; https://doi.org/10.3390/catal15060556 - 3 Jun 2025

Viewed by 1028

Abstract

Utilizing isomeric monomers to construct covalent organic frameworks (COFs) could easily and precisely regulate their structure in order to raise the photocatalytic performance towards two-step single-electron oxygen reduction reaction (ORR) to hydrogen peroxide (H₂O₂). Herein, isomeric anthraquinone (AQ)-based COFs [...] Read more.

Utilizing isomeric monomers to construct covalent organic frameworks (COFs) could easily and precisely regulate their structure in order to raise the photocatalytic performance towards two-step single-electron oxygen reduction reaction (ORR) to hydrogen peroxide (H₂O₂). Herein, isomeric anthraquinone (AQ)-based COFs (designated as 1,4-DQTP and 2,6-DQTP) were successfully fabricated through a simple yet effective one-step solvothermal synthesis approach, only utilizing isomeric monomers with alterations in the catalysts. Specifically, the black 1,4-DQTP displayed a high photocatalytic H₂O₂ production rate of 865.4 µmol g⁻¹ h⁻¹, with 2.44-fold enhancement compared to 2,6-DQTP (354.7 µmol g⁻¹ h⁻¹). Through a series of experiments such as electron paramagnetic resonance (EPR) spectroscopy and the free radical quenching experiments, as well as density functional theory (DFT) calculations, the photocatalytic mechanism revealed that compared with 2,6-DQTP, 1,4-DQTP possessed a stronger and broader visible light absorption capacity, and thus generated more photogenerated e⁻-h⁺ pairs. Ultimately, more photogenerated electrons were enriched on the AQ motif via a more apparent electron push–pull effect, which provided a stable transfer channel for e⁻ and thus facilitated the generation of superoxide anion radical intermediates (•O₂⁻). On the other hand, the negative charge region of AQ’s carbonyl group evidently overlapped with that of TP, indicating that 1,4-DQTP had a higher chemical affinity for the uptake of protons, and thus afforded a more favorable hydrogen donation for H⁺. As a consequence, the rational design of COFs utilizing isomeric monomers could synergistically raise the proton-coupled electron transfer (PCET) kinetics for two-step single-electron ORR to H₂O₂ under visible light illumination. This work provides some insights for the design and fabrication of COFs through rational isomer engineering to modulate their photocatalytic activities. Full article

(This article belongs to the Special Issue Nanostructured Photocatalysts for Hydrogen Production)

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19 pages, 1622 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Enzymatic Production of p-Methoxycinnamate Monoglyceride Under Solventless Conditions: Kinetic Analysis and Product Characterization

by Laura Molinero, Juan J. Tamayo, José J. Gandia, Félix García-Ochoa and Miguel Ladero

Catalysts 2025, 15(6), 548; https://doi.org/10.3390/catal15060548 - 31 May 2025

Viewed by 2476

Abstract

With the increase in biodiesel production experienced in the last decades, biomass-derived glycerol is obtained at a high rate, so glycerol availability in the market has scaled up while this polyol price has been reduced, with the exception of high-quality glycerol. In this [...] Read more.

With the increase in biodiesel production experienced in the last decades, biomass-derived glycerol is obtained at a high rate, so glycerol availability in the market has scaled up while this polyol price has been reduced, with the exception of high-quality glycerol. In this context, novel and sustainable products based on glycerol are actively looked for. Octyl-methoxycinnamate (OMC) is a common cosmetic ingredient and sunscreen with potential activity as an endocrine disruptor that is considered an emergent contaminant in aquatic environments. As possible substituents, glycerol-based methoxycinnamates such as monoglycerides can be obtained via lipase-driven esterification. In this work, we develop an enzymatic process under solventless conditions to obtain p-methoxycinnamate monoglyceride under mild conditions using Novozym 435—an immobilized industrial preparation of the lipase B of Candida antarctica—observing the effect of key process variables such as temperature and enzyme, water and acid concentrations. Furthermore, the obtained product was assessed for its activity as UVB-filter and for its stability under irradiation conditions, showing a similar SPF activity and a much higher stability toward photooxidation than OMC. Full article

(This article belongs to the Special Issue Plant-Derived Biomass Catalytic and Biocatalytic Transformation into Biorefinery Products)

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52 pages, 15996 KB

Open AccessFeature PaperEditor’s ChoiceReview

Current Strategies to Improve the Properties of Graphitic Carbon Nitride for Effective and Scalable Wastewater Pollutant Removal: A Critical Review

by Xan Barreiro-Xardon, Emilio Rosales and María Ángeles Sanromán

Catalysts 2025, 15(6), 523; https://doi.org/10.3390/catal15060523 - 26 May 2025

Cited by 1 | Viewed by 1861

Abstract

Heterogeneous photocatalysis has emerged in recent years as a promising and sustainable decontamination method. However, several drawbacks limit the effective usage of this process up to date, such as photocatalysts’ limited properties, difficulty in modifying and improving their properties, as well as the [...] Read more.

Heterogeneous photocatalysis has emerged in recent years as a promising and sustainable decontamination method. However, several drawbacks limit the effective usage of this process up to date, such as photocatalysts’ limited properties, difficulty in modifying and improving their properties, as well as the environmental impact and cost associated with the use of the metals on which conventional photocatalysts are based. Graphitic carbon nitride (gCN), a new carbon-based photocatalyst, offers the possibility of easy modification and improvement of their properties. There are several strategies to improve the properties of these derivatives, such as increasing the surface area (modifying morphology into 0D, 1D, 2D, or porous structures), increasing the absorption in the visible (doping), and improving the separation and mobility of photogenerated charges (introducing defects, vacancies, functional groups, and doping). In this review, a compilation of these modifications, the associated improvements in its properties, and its derivatives was carried out with focus on the degradation of emerging pollutants (EPs). The property modifications enhance their behavior and efficiency of degradation, all in a cheaper and more sustainable way. Thus, improved gCN derivatives offer real possibilities for the upscaling of heterogeneous photocatalytic processes as an effective alternative for decontaminating water bodies. Full article

(This article belongs to the Special Issue Environmentally Friendly Catalysts for Energy and Water Treatment Applications)

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22 pages, 10616 KB

Open AccessEditor’s ChoiceReview

Recent Progress on High-Efficiency Hydrogen Evolution Electrocatalysis of Heteroatom-Doped MoS₂: A Review

by Cihan Liu, Xinyu Li, Zhiwei Liu, Lexin Zhang, Siyu Jiang and Tifeng Jiao

Catalysts 2025, 15(6), 520; https://doi.org/10.3390/catal15060520 - 25 May 2025

Cited by 1 | Viewed by 2133

Abstract

The exacerbation of the global energy crisis has brought the development of efficient and sustainable hydrogen energy to the forefront of contemporary research endeavors. Molybdenum disulfide (MoS₂), recognized for its outstanding electrocatalytic performance as a two-dimensional material, has attracted significant interest [...] Read more.

The exacerbation of the global energy crisis has brought the development of efficient and sustainable hydrogen energy to the forefront of contemporary research endeavors. Molybdenum disulfide (MoS₂), recognized for its outstanding electrocatalytic performance as a two-dimensional material, has attracted significant interest for its potential in the hydrogen evolution reaction (HER). This review delves into the heteroatom-doped modification strategy centered on MoS₂ and its effectiveness in enhancing electrocatalytic hydrogen evolution. The influence of various doping elements (including noble metals, transition metals, and non-metals) on the electronic structure and catalytic efficiency of MoS₂ is also analyzed, elucidating the mechanism by which heteroatom doping enhances the catalytic performance and stability of MoS₂. Looking ahead, the integration of multiple doping elements, utilization of advanced computational techniques, and advancement of novel synthetic methods position MoS₂ for practical applications in the field of hydrogen energy, driving the progress and improvement of sustainable energy initiatives. Full article

(This article belongs to the Special Issue Novel Catalysts for Environmental Catalysis)

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34 pages, 2339 KB

Open AccessFeature PaperEditor’s ChoiceReview

Process Intensification for CO₂ Hydrogenation to Liquid Fuels

by Simona Renda and Miguel Menéndez

Catalysts 2025, 15(6), 509; https://doi.org/10.3390/catal15060509 - 22 May 2025

Cited by 2 | Viewed by 2177

Abstract

Liquid fuels obtained from CO₂ and green hydrogen (i.e., e-fuels) are powerful tools for decarbonizing economy. Improvements provided by Process Intensification in the existing conventional reactors aim to decrease energy consumption, increase yield, and ensure more compact and safe processes. This review [...] Read more.

Liquid fuels obtained from CO₂ and green hydrogen (i.e., e-fuels) are powerful tools for decarbonizing economy. Improvements provided by Process Intensification in the existing conventional reactors aim to decrease energy consumption, increase yield, and ensure more compact and safe processes. This review describes the advances in the production of methanol, dimethyl ether, and hydrocarbons by Fischer–Tropsch using different Process Intensification tools, mainly membrane reactors, sorption-enhanced reactors, and structured reactors. Due to the environmental interest, this review article focused on discussing methanol and dimethyl ether synthesis from CO₂ + H₂, which also represented the most innovative approach. The use of syngas (CO + H₂) is generally preferred for the Fischer–Tropsch process; hence, studies examining this process were included in the present review. Both mathematical models and experimental results are discussed. Achievements in the improvement of catalytic reactor performance are described. Experimental results in membrane reactors show increased performance in e-fuels production compared to the conventional packed bed reactor. The combination of sorption and reaction also increases the single-pass conversion and yield, although this improvement is limited by the saturation capacity of the sorbent in most cases. Full article

(This article belongs to the Special Issue Fluidizable Catalysts for Novel Chemical Processes)

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18 pages, 1751 KB

Open AccessEditor’s ChoiceArticle

Natural Pyrolusite-Catalyzed Ozonation for Nanoplastics Degradation

by Victor Mello, Julia Nieto-Sandoval, Márcia Dezotti and Carmen Sans

Catalysts 2025, 15(5), 502; https://doi.org/10.3390/catal15050502 - 21 May 2025

Cited by 2 | Viewed by 1050

Abstract

The increasing prevalence of polystyrene nanoplastics (PSNPs) in aquatic environments poses significant risks due to their persistence and potential toxicity. Conventional water treatment methods have proven ineffective in removing these emerging pollutants, highlighting the urgent need for sustainable and efficient treatment. This study [...] Read more.

The increasing prevalence of polystyrene nanoplastics (PSNPs) in aquatic environments poses significant risks due to their persistence and potential toxicity. Conventional water treatment methods have proven ineffective in removing these emerging pollutants, highlighting the urgent need for sustainable and efficient treatment. This study investigates the application of catalytic ozonation using natural pyrolusite (n-MnO₂) and oxalic acid (OA) as a co-catalyst for the environmentally friendly degradation of PSNPs. Key operational parameters, including pH, applied ozone dose, pyrolusite dosage, and OA concentration, were systematically evaluated. Results demonstrate that the MnO₂ + OA + O₃ system enhances the generation of reactive oxygen species (ROS), leading to improved PSNP removal while maintaining the applied ozone dose compared to the single ozonation reaction. The highest TOC removal of 75% was achieved within 30 min of treatment under optimal conditions (pH = 4, [MnO₂] = 0.5 g L⁻¹, [OA] = 10 mg L⁻¹, and ozone dose of 37.5 mg min⁻¹), with significant turbidity reduction, indicating both chemical and physical degradation of PSNPs. Catalyst reusability after three consecutive cycles confirmed minimal loss in activity, reinforcing its potential as a sustainable catalytic system. These findings highlight natural MnO₂-driven catalytic ozonation as a green and effective strategy for nanoplastic removal in water treatment applications. Full article

(This article belongs to the Special Issue Environmentally Friendly Catalysts for Energy and Water Treatment Applications)

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15 pages, 1749 KB

Open AccessEditor’s ChoiceArticle

Optimizing Methane Oxidative Coupling over La₂O₃: Kinetic and Product Analysis

by Zhehao Qiu and Yulu Cai

Catalysts 2025, 15(5), 499; https://doi.org/10.3390/catal15050499 - 20 May 2025

Viewed by 1202

Abstract

The oxidative coupling of methane (OCM) is a promising process for converting methane directly into more valuable ethane and ethylene. In this work, high time resolution online mass spectrometry was employed to track the OCM reaction over a commercial La₂O₃ [...] Read more.

The oxidative coupling of methane (OCM) is a promising process for converting methane directly into more valuable ethane and ethylene. In this work, high time resolution online mass spectrometry was employed to track the OCM reaction over a commercial La₂O₃ catalyst, focusing on the effects of methane to oxygen ratio, gas hourly space velocity (GHSV), and the presence of H₂O and CO in the feed gas on methane conversion and C₂ yield. The results demonstrated that an optimized GHSV (44,640 to 93,000 mL·g⁻¹·h⁻¹) and methane to oxygen ratio (CH₄/O₂ = 3) would achieve the highest methane conversion and C₂ yield at 740 °C. Furthermore, at a GHSV of 44,640 mL·g⁻¹·h⁻¹, the introduction of 1% H₂O into the reaction mixture resulted in a twofold increase in C₂ yield at 650 °C, while the addition of 1% CO led to a threefold increase in C₂ yield at 550 °C. A model in which only the front-end catalyst is active was also developed to show excellent agreement with the experimental data. The relationship between catalytic performance and the effective catalyst position in the catalyst bed provides important insights into optimizing reactor design and operating conditions to maximize C₂ yield and selectivity in the OCM reaction. Full article

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19 pages, 2133 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Electrodeposited Co Crystalline Islands Shelled with Facile Spontaneously Deposited Pt for Improved Oxygen Reduction

by Jelena Golubović, Lazar Rakočević, Vladimir Rajić, Miloš Milović and Svetlana Štrbac

Catalysts 2025, 15(5), 490; https://doi.org/10.3390/catal15050490 - 18 May 2025

Viewed by 912

Abstract

The cobalt crystalline islands (Co_cryst) were electrochemically deposited onto a glassy carbon (GC) support and then modified by a facile spontaneous deposition of platinum. The electrocatalytic activity of the resulting Co_cryst-Pt core-shell catalyst was evaluated for the oxygen reduction [...] Read more.

The cobalt crystalline islands (Co_cryst) were electrochemically deposited onto a glassy carbon (GC) support and then modified by a facile spontaneous deposition of platinum. The electrocatalytic activity of the resulting Co_cryst-Pt core-shell catalyst was evaluated for the oxygen reduction reaction (ORR) in an alkaline medium. The XRD characterization of the Co_cryst-Pt islands revealed that the cobalt core had a hexagonal close-packed (hcp) crystalline structure, and that the platinum shell exhibited a crystalline structure with a preferential (111) orientation. SEM images showed that the average lateral size of the Co_cryst islands was 1.17 μm, which increased to 1.32 μm after adding platinum. The XPS analysis indicated that the outer layer of the bulk metallic Co_cryst islands was fully oxidized. During the spontaneous deposition of platinum, the outer Co(OH)₂ layer was dissolved, leaving the cobalt core in a metallic state, while the platinum shell remained only partially oxidized. The high electrochemically active surface area of the Co_cryst-Pt/GC electrode, along with a suitable crystalline structure of the Co_cryst-Pt islands, contributes to enhancing its ORR activity by providing a greater number of surface active sites for oxygen adsorption and subsequent reduction. The ORR on the Co_cryst-Pt catalyst occurs via a four-electron reaction pathway, with onset and half-wave potentials of 1.07 V and 0.87 V, respectively, which exceed those of polycrystalline platinum and a commercial benchmark Pt/C. Full article

(This article belongs to the Special Issue Insight into Electrocatalysts for Oxygen Reduction Reaction)

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25 pages, 1620 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Laccase-Catalyzed Polymerized Natural Bioactives for Enhanced Mushroom Tyrosinase Inhibition

by Diana Costa, Diana Rocha, Joana Santos, Jennifer Noro, Artur Ribeiro and Carla Silva

Catalysts 2025, 15(5), 481; https://doi.org/10.3390/catal15050481 - 14 May 2025

Viewed by 2290

Abstract

Skin hyperpigmentation disorders, such as melasma, are linked to excessive melanin production, primarily regulated by the enzyme tyrosinase (TYR). While current inhibitors like kojic acid (KA) are effective, they often cause adverse side effects, driving the search for safer andnatural alternatives. This study [...] Read more.

Skin hyperpigmentation disorders, such as melasma, are linked to excessive melanin production, primarily regulated by the enzyme tyrosinase (TYR). While current inhibitors like kojic acid (KA) are effective, they often cause adverse side effects, driving the search for safer andnatural alternatives. This study evaluated the TYR inhibitory potential of bioactive-rich extracts from acorn, cocoa, cork, and eucalyptus, extracted using hydroethanolic (HE) and natural deep eutectic solvents (NADES), and explored the enhancement of their bioactivity through laccase-assisted polymerization. NADES significantly improved extraction yields and preserved bioactive compounds, with cocoa extracts showing the highest TYR inhibition. Laccase-mediated polymerization further enhanced TYR inhibitory activity, particularly of NADES extracts, suggesting a more effective and sustainable approach for skincare applications. The results highlight the potential of combining green chemistry principles with enzymatic catalysis to develop eco-friendly and efficient treatments for hyperpigmentation disorders, offering a promising alternative to conventional methods. Full article

(This article belongs to the Special Issue The Design of Protein-Based Catalysts)

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18 pages, 4175 KB

Open AccessEditor’s ChoiceArticle

Co-Doped Ni@Ni(OH)₂ Core–Shell Catalysts for Dual-Function Water and Urea Oxidation

by Saba A. Aladeemy, Maged N. Shaddad, Talal F. Qahtan, Abdulrahman I. Alharthi, Kamal Shalabi, Abdullah M. Al-Mayouf and Prabhakarn Arunachalam

Catalysts 2025, 15(5), 474; https://doi.org/10.3390/catal15050474 - 12 May 2025

Viewed by 1594

Abstract

Crystalline–amorphous core–shell-like heterostructures have attracted considerable attention in electrocatalysis due to their unique electronic and structural properties; however, tuning the surface composition of the amorphous shell remains a major challenge. In this work, we report a simple, low-cost, one-pot hydrazine-assisted chemical deposition method [...] Read more.

Crystalline–amorphous core–shell-like heterostructures have attracted considerable attention in electrocatalysis due to their unique electronic and structural properties; however, tuning the surface composition of the amorphous shell remains a major challenge. In this work, we report a simple, low-cost, one-pot hydrazine-assisted chemical deposition method for synthesizing a series of Co-doped Ni@Ni(OH)₂ catalysts with a crystalline Ni core and an amorphous Ni(OH)₂ shell. Among the prepared catalysts, the sample containing 10 wt.% cobalt (denoted as b-Co-doped Ni@Ni(OH)₂) exhibited the highest electrocatalytic activity toward both the oxygen evolution reaction (OER) and the urea oxidation reaction (UOR). In 1.0 M KOH, the b-Co-doped Ni@Ni(OH)₂ catalyst achieved a 40 mV lower overpotential at 50 mA·cm⁻² compared to undoped Ni@Ni(OH)₂ for the OER. For the UOR in 0.33 M urea/1.0 M KOH, it delivered approximately twice the anodic current density relative to the undoped sample, along with improved reaction kinetics as evidenced by a Tafel slope of 70.7 mV·dec⁻¹. This performance enhancement is attributed to the optimized core–shell-like architecture, cobalt doping-induced electronic modulation, increased electrochemically active surface area, and improved charge transfer efficiency. Overall, this study demonstrates a promising and scalable strategy for designing advanced Ni-based bifunctional catalysts for sustainable energy conversion and wastewater treatment applications. Full article

(This article belongs to the Special Issue Nanocatalysis: Integrating Sustainability and Innovation Across Diverse Applications)

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33 pages, 6057 KB

Open AccessFeature PaperEditor’s ChoiceReview

Evaluating Theoretical Approaches to Nitrogen-Doped Carbon Supports

by Vu Nguyen and Shubham Vyas

Catalysts 2025, 15(5), 473; https://doi.org/10.3390/catal15050473 - 11 May 2025

Viewed by 1625

Abstract

Catalysis requires extrapolations from computational models to the catalytic activity observed under practical operating conditions, especially for single-atom catalysts, to be made. Thus, it is necessary to understand the fundamental interactions at an atomistic level to rationally design systems for targeted practical applications. [...] Read more.

Catalysis requires extrapolations from computational models to the catalytic activity observed under practical operating conditions, especially for single-atom catalysts, to be made. Thus, it is necessary to understand the fundamental interactions at an atomistic level to rationally design systems for targeted practical applications. With that in mind, the key aspects and parameterization of these model systems are especially important as they will heavily affect the validity of those extrapolations. Rigorously developed models and protocols with well-defined and understood metrics and interactions are reviewed to begin to provide an overview of the best theoretical practices for designing nitrogen-doped carbon supports. Full article

(This article belongs to the Special Issue Single-Atom Catalysts: Current Trends, Challenges, and Prospects)

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27 pages, 8137 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Graphene Oxide-Supported Metal Catalysts for Selective Hydrogenation of Cinnamaldehyde: Impact of Metal Choice and Support Structure

by Martina Pitínová, Iryna Danylo, Ayesha Shafiq, Tomáš Hartman, Mariia Khover, Berke Sevemez, Lukáš Koláčný and Martin Veselý

Catalysts 2025, 15(5), 470; https://doi.org/10.3390/catal15050470 - 10 May 2025

Viewed by 6161

Abstract

This study explores the selective hydrogenation of cinnamaldehyde using a series of metal catalysts supported on reduced graphene oxide (rGO) and conventional activated carbon (AC). Catalysts based on Pt, Pd, Rh, Ru, and Co were synthesized with controlled metal loading and characterized by [...] Read more.

This study explores the selective hydrogenation of cinnamaldehyde using a series of metal catalysts supported on reduced graphene oxide (rGO) and conventional activated carbon (AC). Catalysts based on Pt, Pd, Rh, Ru, and Co were synthesized with controlled metal loading and characterized by XRD, SEM-EDS, XRF, and TEM. Among all tested materials, Pd supported on rGO synthesized via the Tour method (Pd/rTOGO) exhibited the highest catalytic activity, achieving 62% conversion of cinnamaldehyde and superior selectivity toward hydrocinnamaldehyde (HCAL). The support material had a significant influence on performance, especially for Pd catalysts, where 2D rGO outperformed 3D AC in both conversion and selectivity. In contrast, other metals (Pt, Rh, Ru, Co) showed only modest activity and limited selectivity tuning via support choice. Notably, GC-MS analysis revealed the formation of a previously underreported side product, 3-isopropoxy-propan-1-yl benzene (ether), likely formed via reductive etherification in isopropanol. The combined kinetic and selectivity data enabled the proposal of reaction pathways, including rapid transformation of cinnamylalcohol (COL) to hydrocinnamal alcohol (HCOL) and HCAL to ether. These findings emphasize the importance of support structure and surface functionality, particularly in 2D carbon materials, for designing efficient and selective hydrogenation catalysts. Full article

(This article belongs to the Special Issue Catalysis by Metals and Metal Oxides)

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31 pages, 2489 KB

Open AccessEditor’s ChoiceReview

Current Progress in Advanced Oxidation Processes for the Removal of Contaminants of Emerging Concern Using Peracetic Acid as an Effective Oxidant

by Bakhta Bouzayani, Sourour Chaâbane Elaoud and Maria Ángeles Sanromán

Catalysts 2025, 15(5), 469; https://doi.org/10.3390/catal15050469 - 10 May 2025

Cited by 2 | Viewed by 2516

Abstract

The growing diversity and prevalence of contaminants of emerging concern (CECs) in aquatic environments present significant risks to human health and ecosystems, necessitating the development of effective remediation strategies. Advanced oxidation processes (AOPs) have emerged as a promising solution due to their ability [...] Read more.

The growing diversity and prevalence of contaminants of emerging concern (CECs) in aquatic environments present significant risks to human health and ecosystems, necessitating the development of effective remediation strategies. Advanced oxidation processes (AOPs) have emerged as a promising solution due to their ability to produce highly reactive species that efficiently degrade persistent contaminants. Among the various oxidizing agents, peracetic acid (PAA) has attracted significant attention in the field of water treatment for its powerful oxidative properties, environmentally safe decomposition, and ease of use. This article is designed to offer a comprehensive overview of the latest trends in PAA-based AOPs. The discussion begins with an overview of the intrinsic performance of PAA, emphasizing its oxidation potential and degradation mechanisms. Subsequently, the effectiveness of PAA-based AOPs in remediating CECs is explored, focusing on transition metal-mediated activation (Fe, Co, Mn), UV irradiation, and carbon-based catalysts, all of which enhance the generation of reactive species (RS). Next, the determination of RS in PAA-based AOPs is examined, distinguishing between free radical (organic and inorganic) and non-radical (singlet oxygen and high-valent metal) mechanisms that govern pollutant degradation. Then, key factors affecting the removal of CECs in PAA-based AOPs, including initial PAA concentration, catalyst dosage, and pH, are also addressed. Following that, the potential by-products and hazard assessments associated with PAA oxidation are discussed. Finally, current challenges and future research directions are proposed to facilitate the large-scale application of PAA-based AOPs in water remediation. Full article

(This article belongs to the Special Issue Advances in Enhancement of Catalytic Performance for Wastewater Treatment)

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46 pages, 4217 KB

Open AccessEditor’s ChoiceReview

Comprehensive Insights into Photoreforming of Waste Plastics for Hydrogen Production

by E. M. N. Thiloka Edirisooriya, Punhasa S. Senanayake, Tarek Ahasan, Pei Xu and Huiyao Wang

Catalysts 2025, 15(5), 453; https://doi.org/10.3390/catal15050453 - 7 May 2025

Cited by 4 | Viewed by 3766

Abstract

The global plastic crisis, with over 400 million metric tons produced annually and minimal recycling, demands urgent solutions. Photocatalytic plastic photoreforming offers a dual benefit: converting non-recyclable plastics into hydrogen fuel and valuable chemicals using solar energy under mild conditions. This critical review [...] Read more.

The global plastic crisis, with over 400 million metric tons produced annually and minimal recycling, demands urgent solutions. Photocatalytic plastic photoreforming offers a dual benefit: converting non-recyclable plastics into hydrogen fuel and valuable chemicals using solar energy under mild conditions. This critical review highlights recent advances in photocatalyst design, including semiconductors, MOF-derived materials, and co-catalyst systems, and explores key insights into plastic degradation mechanisms and reactor configurations. Operational factors such as pH, light intensity, and flow dynamics are discussed for their impact on hydrogen yield and product selectivity. Life cycle and techno-economic assessments reveal current challenges in efficiency, scalability, and cost to illuminate the feasibility of implementing the technology at industrial scale. This study suggests that innovations in catalyst engineering, light management, and system integration provide viable paths forward. With its potential to upcycle plastic waste and contribute to low-carbon hydrogen economies, photoreforming represents a promising approach in advancing circular economy goals, especially when coupled with policy support and smart separation strategies. Full article

(This article belongs to the Special Issue Recent Developments in Photocatalytic Hydrogen Production)

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25 pages, 2556 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Exploration of CYP4B1 Substrate Promiscuity Across Three Species

by Annika Röder, Michael C. Hutter, Eva Heitzer, Pia Josephine Franz, Saskia Hüsken, Constanze Wiek and Marco Girhard

Catalysts 2025, 15(5), 454; https://doi.org/10.3390/catal15050454 - 7 May 2025

Viewed by 1466

Abstract

Enzymes of the cytochrome P450 monooxygenase family 4 (CYP4) in mammals are generally involved either in endobiotic metabolism (e.g., acting on fatty acids or eicosanoids), or the modification of xenobiotics including therapeutic drugs. CYP4B1 is special, as it is an enigmatic enzyme acting [...] Read more.

Enzymes of the cytochrome P450 monooxygenase family 4 (CYP4) in mammals are generally involved either in endobiotic metabolism (e.g., acting on fatty acids or eicosanoids), or the modification of xenobiotics including therapeutic drugs. CYP4B1 is special, as it is an enigmatic enzyme acting at the interface between xenobiotic and endobiotic metabolism. However, a systematic analysis of CYP4B1’s substrate scope has not yet been reported. Herein, a three-step approach to identify novel substrates for three CYP4B1 orthologs (namely from rabbits, green monkeys, and mouse lemurs) is described. First, screening of a library containing 502 natural products revealed potential novel substrate groups for CYP4B1. Second, based on these results, a systematic library was defined consisting of 63 compounds representing 10 compound groups. Third, in vitro conversion of these compounds by CYP4B1 and identification of conversion products were conducted, supported by in silico docking, allowing the prediction of binding probabilities and potential oxidation sites. We report five new substrate groups (acyclic, monocyclic and bicyclic terpenoids, stilbenoids, and vanilloids), twenty-eight new substrates (inter alia capsaicin, gingerol, genistein, stilbene, myristicin, thioanisole), and two new reaction types for CYP4B1 (S-oxidation, O-demethylation). Consequently, CYP4B1 is a far more promiscuous enzyme than previously thought. Full article

(This article belongs to the Special Issue Applications of Catalytic Reactions in Promoting the Health of Organisms)

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15 pages, 5851 KB

Open AccessEditor’s ChoiceArticle

Unlocking Synergistic Catalysis in NiP: Dual Role of Electronic Structure and Lewis Acidity for Enhanced Oxygen Evolution Reaction

by Jiazhou Liang, Jiawei Li, Jiani Yan, Andrew M. Rappe and Jing Yang

Catalysts 2025, 15(5), 457; https://doi.org/10.3390/catal15050457 - 7 May 2025

Cited by 1 | Viewed by 867

Abstract

Nickel phosphides (Ni_xP_y) are recognized as promising alternatives to noble-metal catalysts for the oxygen evolution reaction (OER). NiP, consisting of the equal stoichiometric ratio of Ni and P, could help quantify the catalytic effect of P and Ni. In [...] Read more.

Nickel phosphides (Ni_xP_y) are recognized as promising alternatives to noble-metal catalysts for the oxygen evolution reaction (OER). NiP, consisting of the equal stoichiometric ratio of Ni and P, could help quantify the catalytic effect of P and Ni. In this work, density functional theory (DFT) is employed to investigate the OER mechanism on NiP surfaces. We found that P atoms help stabilize O* at the adsorption sites. The rich electron donation from the Ni atom can alter the local charge distribution and enhance the interaction between O* and P atoms. Both oxygen intermediate adsorption energy and OER overpotential exhibit linear correlations with the charge of adsorption sites. Electron loss at the site induces the overall system to exhibit Lewis acidic characteristics, facilitating the OER and leading to a substantial overpotential reduction of up to 0.61 V compared to Lewis basic structures. Leveraging electronic structure theory and Lewis acid–base theory, we offer a new insight into the OER mechanism on the NiP surface, demonstrating that the catalytic activity of bulk metallic surface materials like NiP can be optimized by tailoring the local surface chemical environment. Full article

(This article belongs to the Special Issue Design and Application of Combined Catalysis)

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19 pages, 3870 KB

Open AccessEditor’s ChoiceArticle

Gliding Arc Plasma Synthesis of MnO₂ Nanomaterials for Catalytic Oxidation of Benzene: Effect of Plasmagenic Gas

by Franck W. Boyom-Tatchemo, François Devred, Elie Acayanka, Georges Kamgang-Youbi, Samuel Laminsi and Eric M. Gaigneaux

Catalysts 2025, 15(5), 451; https://doi.org/10.3390/catal15050451 - 5 May 2025

Viewed by 812

Abstract

MnO₂ nanostructures were successfully synthesized via the reduction of KMnO₄ solutions using the gliding arc plasma (Plasma Glidarc) approach. Here, we highlight the effect of different plasmagenic gases, such as moist air (atmospheric air), dry air, nitrogen (N₂) or [...] Read more.

MnO₂ nanostructures were successfully synthesized via the reduction of KMnO₄ solutions using the gliding arc plasma (Plasma Glidarc) approach. Here, we highlight the effect of different plasmagenic gases, such as moist air (atmospheric air), dry air, nitrogen (N₂) or oxygen (O₂). The obtained materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), nitrogen physisorption and scanning electron microscopy (SEM). The crystalline structures of obtained MnO₂ polymorphs are mainly γ-MnO₂ and α-MnO₂, regardless of the feeding gas. The main reactive species, in addition to nitrogenous species like NO· radical generated with moist air, dry air or N₂ gas, other oxygenated species such as H₂O₂ (E°(O₂/H₂O₂) = 0.69 V) are produced with O₂ able to reduce KMnO₄ solution (E°(KMnO₄/MnO₂) = 1.70 V). Helium gas did not allow for the plasma reduction of the KMnO₄ solution, even after 60 min of exposure. Furthermore, gas humidification did not significantly affect the precipitation time or the properties of plasma-synthesized MnO₂. Atmospheric humidified air appears to be the best plasmagenic gas, as it allows for a shorter synthesis time and leads to a large specific surface area. All plasma-synthesized MnO₂ showed good activity during the catalytic oxidation of benzene. The use of different MnO₂ polymorphs (α-, δ- and γ-MnO₂) showed that, in addition to the specific surface area, the crystalline structure significantly affects the catalytic oxidation of benzene. K⁺ species inserted within the MnO₂ structure allow for their stability during the catalytic process. This work highlights the possibility to use different plasmagenic gases to prepare MnO₂ nanostructures through plasma glidarc for the catalytic oxidation of benzene. Full article

(This article belongs to the Special Issue Nanocatalysts in Energy and Environmental Applications)

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18 pages, 7664 KB

Open AccessEditor’s ChoiceArticle

Single-Atom and Sub-Nano Ruthenium Cluster Catalysts—Application to Biomass Upgrading into Biofuel Additive

by Chaima Z. Tabet-Zatla, Sumeya Bedrane, José Juan Calvino, Miguel Ángel Cauqui, Fayçal Dergal, Redouane Bachir, Chewki Ziani-Cherif and Juan Carlos Hernández-Garrido

Catalysts 2025, 15(5), 449; https://doi.org/10.3390/catal15050449 - 3 May 2025

Viewed by 1453

Abstract

Sub-nano metal clusters have important physicochemical features that lead to a wide range of applications. Herein, we point out an unfailing reproducible protocol to synthesize ruthenium single-atom catalysts and ultra-small clusters supported on various silica–alumina mixed oxides. The catalysts were synthesized via a [...] Read more.

Sub-nano metal clusters have important physicochemical features that lead to a wide range of applications. Herein, we point out an unfailing reproducible protocol to synthesize ruthenium single-atom catalysts and ultra-small clusters supported on various silica–alumina mixed oxides. The catalysts were synthesized via a dendrimer-free, sonication-assisted route, with ruthenium loadings up to 2 wt%. Raman spectroscopy mapping revealed a wide coverage of the materials’ surfaces by ruthenium, while HAADF-STEM evidenced that 100% of the ruthenium was at the sub-nano scale, with up to 74% of the single atoms and metal clusters having an average size between 0.3 and 0.7 nm, independently of the support or the metal’s loading. These materials exhibited highly selective size-dependent catalytic performances in upgrading biomass-derived furfural into transportation biofuel additive 2,2′-difurfurylether, with turnover frequencies up to 1148 h⁻¹. Ruthenium single atoms and sub-nano clusters showed an exceptional resistance to sintering, with a size variation of ±0.1 nm before and after reaction, and no metal leaching was observed. Full article

(This article belongs to the Special Issue Catalytic Biomass Conversions into Fuels and Materials—Sustainable Technologies and Applications)

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13 pages, 3220 KB

Open AccessFeature PaperEditor’s ChoiceArticle

CoMo/SS Cathode Catalyst for Enhanced Hydrogen Production in Microbial Electrolysis Cells

by Gao Lei, Yaoqiang Wang, Gang Xiao and Haijia Su

Catalysts 2025, 15(5), 439; https://doi.org/10.3390/catal15050439 - 30 Apr 2025

Cited by 3 | Viewed by 1276

Abstract

Hydrogen energy has emerged as a pivotal clean energy solution due to its sustainability and zero-emission potential. Microbial electrolysis cells are a promising technology for renewable hydrogen production, typically relying on expensive and unstable Pt/C catalysts for the hydrogen evolution reaction (HER). To [...] Read more.

Hydrogen energy has emerged as a pivotal clean energy solution due to its sustainability and zero-emission potential. Microbial electrolysis cells are a promising technology for renewable hydrogen production, typically relying on expensive and unstable Pt/C catalysts for the hydrogen evolution reaction (HER). To address these limitations, this study develops a cost-effective and durable alternative approach. A cobalt–molybdenum (Co-Mo) alloy catalyst (denoted as CoMo/SS) was synthesized via a one-step electrodeposition method on 1000-mesh 316L stainless steel at a current density of 30 mA·cm⁻² for 80 min, using an electrolyte with a Co-to-Mo ratio of 1:1. The electrochemical properties and hydrogen evolution performance of this catalyst in a microbial electrolysis cell were evaluated. Key results demonstrate that the CoMo/SS catalyst achieves a good catalytic performance of hydrogen evolution. The CoMo/SS cathode catalyst only requires an overpotential of 91.70 mV (vs. RHE) to reach a current density of 10 mA·cm⁻² in 1 mol·L⁻¹ KOH, with favorable kinetics, evidenced by a reduced Tafel slope of 104.10 mV·dec⁻¹, enhanced charge transfer with a charge transfer resistance of 4.56 Ω, and a double-layer capacitance of 34.73 mF·cm⁻². Under an applied voltage of 0.90 V, the CoMo/SS cathode exhibited a hydrogen production rate of 1.12 m³·m⁻³·d⁻¹, representing a 33.33% improvement over bare SS mesh. This performance highlights the catalyst’s potential as a viable Pt/C substitute for scalable MEC applications. Full article

(This article belongs to the Section Electrocatalysis)

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15 pages, 5083 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Evaluation of the Environmental and Operating Parameters of a Modern Compression-Ignition Engine Running on Vegetable Fuels with a Catalytic Additive

by Tomasz Osipowicz

Catalysts 2025, 15(5), 440; https://doi.org/10.3390/catal15050440 - 30 Apr 2025

Cited by 2 | Viewed by 723

Abstract

This article discusses the possibility of using a liquid catalyst in selected vegetable fuels. The fuels selected for study are rapeseed oil methyl ester and hemp oil methyl ester. The aim of the research presented in this paper is to evaluate the operating [...] Read more.

This article discusses the possibility of using a liquid catalyst in selected vegetable fuels. The fuels selected for study are rapeseed oil methyl ester and hemp oil methyl ester. The aim of the research presented in this paper is to evaluate the operating and environmental performance of an engine fueled with selected fuels with a catalytic additive. The tests were carried out on a dynamometer bench using a Fiat 1.3 JTD common rail engine. During the tests, parameters such as engine torque and power, specific fuel consumption, and the emission of nitrogen oxides, hydrocarbons, carbon dioxide, and soot were measured. The tests were carried out on fuels with and without a catalytic converter. The results show that the use of a catalytic additive reduces nitrogen oxides and hydrocarbon emissions for all fuels tested. Full article

(This article belongs to the Special Issue Advanced Catalysts Design and Catalytic Conversion of Biomass to High-Value Products)

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23 pages, 6986 KB

Open AccessEditor’s ChoiceReview

Recent Advances in the Synthesis of Quinolines: A Focus on Oxidative Annulation Strategies

by Mao-Lin Liao, Peng-Peng Liu, Jia-Cheng Yang, Ping-Gui Li and Liang-Hua Zou

Catalysts 2025, 15(5), 441; https://doi.org/10.3390/catal15050441 - 30 Apr 2025

Cited by 2 | Viewed by 6325

Abstract

Quinoline, a heterocyclic scaffold of paramount importance in medicinal and industrial chemistry, has garnered significant attention due to its versatile applications. Traditional synthetic methods, dating back over a century, have evolved into innovative strategies leveraging catalytic C–H bond activation, transition-metal-free protocols, and photo-induced [...] Read more.

Quinoline, a heterocyclic scaffold of paramount importance in medicinal and industrial chemistry, has garnered significant attention due to its versatile applications. Traditional synthetic methods, dating back over a century, have evolved into innovative strategies leveraging catalytic C–H bond activation, transition-metal-free protocols, and photo-induced oxidative cyclization. Recent advancements highlight the synergistic roles of catalysts, oxidants, and solvents in enhancing molecular reactivity and reaction efficiency. This review systematically summarizes state-of-the-art oxidative annulation techniques for quinoline synthesis, emphasizing mechanistic insights and practical applications. Full article

(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)

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32 pages, 4374 KB

Open AccessFeature PaperEditor’s ChoiceReview

Catalytic Aspects of Liquid Organic Hydrogen Carrier Technology

by Róbert Barthos, Ferenc Lónyi, Yuting Shi, Ágnes Szegedi, Anna Vikár, Hanna E. Solt and Gyula Novodárszki

Catalysts 2025, 15(5), 427; https://doi.org/10.3390/catal15050427 - 27 Apr 2025

Cited by 1 | Viewed by 4092

Abstract

The surge in photovoltaic (PV) power generation has made it increasingly difficult to integrate the intermittent PV industry into the power grid while maintaining grid stability. The solution is to use the seasonal surplus of PV electricity to produce “green” hydrogen through water [...] Read more.

The surge in photovoltaic (PV) power generation has made it increasingly difficult to integrate the intermittent PV industry into the power grid while maintaining grid stability. The solution is to use the seasonal surplus of PV electricity to produce “green” hydrogen through water electrolysis and then use the hydrogen as an energy source or as a reactant in chemical processes in the chemical industry to produce value-added products. However, the development of advanced hydrogen storage technologies to ensure the safe handling, transportation, and distribution of H₂ is a major issue. The use of stable liquid organic hydrogen carriers (LOHCs) has emerged as a suitable technology for hydrogen storage. This review highlights prospective LOHC technologies based on reversible catalytic hydrogenation–dehydrogenation cycles of liquid organic molecules for hydrogen storage and release under mild temperature and pressure conditions. The state-of-the-art LOHC systems are critically reviewed, highlighting the most effective heterogeneous catalytic systems. Full article

(This article belongs to the Special Issue Sustainable Catalysis for Green Chemistry and Energy Transition)

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23 pages, 5898 KB

Open AccessEditor’s ChoiceReview

Carbon Dioxide Activation and Hydrogenation into Value-Added C1 Chemicals over Metal Hydride Catalysts

by Malesela A. Mafokoane, Xiaoxia Ou, Nicholas M. Musyoka and Fei Chang

Catalysts 2025, 15(5), 424; https://doi.org/10.3390/catal15050424 - 26 Apr 2025

Cited by 1 | Viewed by 1783

Abstract

The utilisation of fossil fuels has resulted in the continuous increase in anthropogenic carbon dioxide (CO₂) emissions and has led to significant environmental impacts. To this end, the catalytic hydrogenation of captured CO₂ into value-added C1 chemicals has attracted great [...] Read more.

The utilisation of fossil fuels has resulted in the continuous increase in anthropogenic carbon dioxide (CO₂) emissions and has led to significant environmental impacts. To this end, the catalytic hydrogenation of captured CO₂ into value-added C1 chemicals has attracted great attention. In this case, significant research efforts have been directed towards the development of heterogeneous catalysts. Owing to the unique properties and functionalities of hydridic hydrogen (H⁻), metal hydrides have shown great promise in hydrogen-involved catalytic processes. This is attributed to their enhanced hydrogen (H₂) absorption-desorption reversibility and newly developed active sites. Nevertheless, their application in the activation and hydrogenation of CO₂ has been overlooked. In this review paper, we provide an overview of recent advances in catalytic CO₂ hydrogenation using metal hydride-based materials. Firstly, the reaction mechanisms of CO₂ hydrogenation toward different C1 products (CO, CH₄, CH₃OH and HCOOH) are introduced to better understand their application trend. Thereafter, we highlight the challenges of developing robust hydride catalysts with different components and structures that enable tuning of their catalytic activity and selectivity. A brief introduction of the CO₂ hydrogenation over typical homogeneous metal hydrides complexes is also presented. Lastly, conclusion, future outlook and perspectives are discussed. Full article

(This article belongs to the Special Issue Feature Review Papers in Catalysis for Sustainable Energy)

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23 pages, 4612 KB

Open AccessFeature PaperEditor’s ChoiceReview

Advancements in Chemical Recycling Catalysts for Plastic Waste in South Korea

by Taemin Jang, Ik Shin, Jungwook Choi, Sohyeon Lee, Hyein Hwang, Minchang Kim and Byung Hyo Kim

Catalysts 2025, 15(5), 414; https://doi.org/10.3390/catal15050414 - 23 Apr 2025

Cited by 1 | Viewed by 5229

Abstract

Plastics are widely used in various industries because of their light weight, low cost, and high durability. The mass production and consumption of plastics have led to a rapid increase in plastic waste problem, necessitating the development of effective recycling technologies. The chemical [...] Read more.

Plastics are widely used in various industries because of their light weight, low cost, and high durability. The mass production and consumption of plastics have led to a rapid increase in plastic waste problem, necessitating the development of effective recycling technologies. The chemical recycling of plastics has emerged as a promising strategy to address these challenges, enabling the conversion of plastic waste into high-purity monomers or oils, even from contaminated or mixed plastic feedstock. This review focuses on the development of catalysts for the chemical recycling of plastics in South Korea, which has one of the highest per capita plastic consumption rates and both academic and industrial efforts in this field. We examine catalytic depolymerization processes for recovering monomers from polymers, such as polyethylene terephthalate (PET) and polycarbonate (PC), as well as catalytic pyrolysis processes for polyolefins, including polyethylene (PE), polypropylene (PP), and polystyrene (PS). By summarizing recent academic research and industrial initiatives in South Korea, this review highlights the strategic role of the country in advancing chemical recycling. Moreover, this review proposes future research directions including the development of reusable catalysts, energy-efficient recycling process, and strategies for recycling mixed or contaminated plastic waste. Full article

(This article belongs to the Special Issue State of the Art of Catalytical Technology in Korea, 2nd Edition)

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28 pages, 10138 KB

Open AccessFeature PaperEditor’s ChoiceReview

Carbon Nitride and Its Hybrid Photocatalysts for CO₂ Reduction C1 Product Selectivity

by Zhi Zhu, Wei Wang, Hongping Li, Jun Zhao and Xu Tang

Catalysts 2025, 15(5), 408; https://doi.org/10.3390/catal15050408 - 22 Apr 2025

Cited by 1 | Viewed by 2314

Abstract

The transformation of abundant and cost-effective CO₂ molecules into valuable chemical feedstocks or fuels represents an appealing yet challenging research objective. Artificial photosynthesis offers a promising pathway for CO₂ reduction reactions (CO₂RR) under mild and environmentally friendly conditions. Graphitic [...] Read more.

The transformation of abundant and cost-effective CO₂ molecules into valuable chemical feedstocks or fuels represents an appealing yet challenging research objective. Artificial photosynthesis offers a promising pathway for CO₂ reduction reactions (CO₂RR) under mild and environmentally friendly conditions. Graphitic carbon nitride (g-C₃N₄) has attracted significant attention for its potential to enhance the efficiency and selectivity of CO₂RR through synthesis and modification strategies. This review explores recent advancements in g-C₃N₄ and its hybrid photocatalysts for selective CO₂ conversions. We examine key factors influencing CO₂RR product selectivity, including electron count and reaction dynamics, CO₂ and reduction intermediates adsorption/desorption, and proton regulation affecting competitive hydrogen evolution. By summarizing various strategies to enhance CO₂ photoreduction performance, this work provides a comprehensive analysis of CO₂RR selectivity mechanisms for each approach. This review aims to inspire research endeavors towards developing efficient artificial systems for enhanced CO₂RR efficiency and product selectivity. Full article

(This article belongs to the Special Issue Recent Advances in Photocatalytic CO₂ Reduction)

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20 pages, 3643 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Unlocking Catalytic Efficiency: How Preparation Strategies and Copper Loading Enhance Hydroxyapatite Catalysts for NH₃ Oxidation

by Sebastiano Campisi, Melissa Greta Galloni and Antonella Gervasini

Catalysts 2025, 15(4), 405; https://doi.org/10.3390/catal15040405 - 21 Apr 2025

Cited by 2 | Viewed by 1121

Abstract

The selective catalytic oxidation of ammonia (NH₃-SCO) is gaining attention due to the hazardous nature of NH₃ and its inclusion in emission reduction frameworks such as the National Emission Ceilings Directive and the Gothenburg Protocol (1999). Copper-based hydroxyapatite (Cu/HAP) catalysts [...] Read more.

The selective catalytic oxidation of ammonia (NH₃-SCO) is gaining attention due to the hazardous nature of NH₃ and its inclusion in emission reduction frameworks such as the National Emission Ceilings Directive and the Gothenburg Protocol (1999). Copper-based hydroxyapatite (Cu/HAP) catalysts have emerged as a promising solution, offering high activity and cost-effectiveness. This study evaluated two preparation methods: a one-pot co-precipitation technique and post-synthesis copper deposition, varying both the contact time and copper concentration. The influence of copper loading and preparation method on catalyst performance in NH₃-SCO was investigated in a continuous flow reactor over a temperature range of 200–500 °C, with a fixed gas hourly space velocity (GHSV) of 120,000 h⁻¹ and an NH₃/O₂ ratio of 0.03. X-ray diffraction and DR-UV spectroscopy confirmed the high crystallinity of HAP and provided insights into copper speciation. X-ray photoelectron spectroscopy revealed that Cu/HAP catalysts prepared via one-pot co-precipitation predominantly contained isolated Cu²⁺ species, which were associated with high catalytic activity in selective NH₃-SCO. Conversely, a higher degree of copper structuring was observed in catalysts prepared by post-synthesis deposition, particularly at higher Cu loadings. These findings highlight the potential to tailor Cu structuring on HAP to enhance performance in NH₃-SCO through optimized preparation strategies. Full article

(This article belongs to the Special Issue New Trends in Catalysis: ELITECAT 2024)

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19 pages, 3763 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Synthesis of Nitrogen-Doped Biomass-Based Activated-Carbon-Supported Nickel Nanoparticles for Hydrazine Oxidation

by Virginija Ulevičienė, Aldona Balčiūnaitė, Daina Upskuvienė, Ance Plavniece, Aleksandrs Volperts, Galina Dobele, Aivars Zhurinsh, Gediminas Niaura, Loreta Tamašauskaitė-Tamašiūnaitė and Eugenijus Norkus

Catalysts 2025, 15(4), 400; https://doi.org/10.3390/catal15040400 - 19 Apr 2025

Cited by 1 | Viewed by 1245

Abstract

In this study we present an application of wood biomass—alder wood char—as the carbon precursor for the synthesis of novel and sustainable nitrogen-doped activated-carbon-supported nickel nanoparticle catalyst (AWC-Ni-N) for hydrazine oxidation. For comparison, the wood-based carbon material doped with nitrogen only (AWC-N) was [...] Read more.

In this study we present an application of wood biomass—alder wood char—as the carbon precursor for the synthesis of novel and sustainable nitrogen-doped activated-carbon-supported nickel nanoparticle catalyst (AWC-Ni-N) for hydrazine oxidation. For comparison, the wood-based carbon material doped with nitrogen only (AWC-N) was also synthesized. Extensive characterization, including SEM, Raman spectroscopy, XPS, and XRD revealed the catalysts’ microstructure and properties. Electrochemical testing demonstrated that the AWC-Ni-N catalyst significantly enhanced the efficiency of the hydrazine oxidation reaction. In addition, direct N₂H₄-H₂O₂ single-fuel-cell tests were conducted using the prepared AWC-N and AWC-Ni-N catalysts as the anodes and cathodes. Peak power densities of up to 10.8 mW cm⁻² were achieved at 25 °C, corresponding to a current density of 27 mA cm⁻² and a cell voltage of 0.4 V when the AWC-Ni-N catalyst was used as both the anode and cathode. Furthermore, the peak power density increased by approximately 1.6 and 2.9 times, respectively, when the operating temperature was raised from 25 °C to 55 °C for the AWC-N and AWC-Ni-N catalysts. Overall, the AWC-N and AWC-Ni-N catalysts demonstrated significant potential as anode and cathode materials in direct N₂H₄-H₂O₂ fuel cells. Full article

(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Biomass Catalytic Conversion)

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75 pages, 20332 KB

Open AccessFeature PaperEditor’s ChoiceReview

A Review on the Research Progress of Zeolite Catalysts for Heavy Oil Cracking

by Lisha Wei, Hui Wang, Qi Dong, Yongwang Li and Hongwei Xiang

Catalysts 2025, 15(4), 401; https://doi.org/10.3390/catal15040401 - 19 Apr 2025

Cited by 13 | Viewed by 6930

Abstract

The efficient utilization of heavy oil is of great significance to alleviating the global energy crisis. How to efficiently convert heavy oil into high-value-added light fuel oil has become a hot issue in the field of petrochemicals. As the residual part of crude [...] Read more.

The efficient utilization of heavy oil is of great significance to alleviating the global energy crisis. How to efficiently convert heavy oil into high-value-added light fuel oil has become a hot issue in the field of petrochemicals. As the residual part of crude oil processing, heavy oil has a complex composition and contains polycyclic aromatic hydrocarbons, long-chain alkanes, and heteroatom compounds, which makes it difficult to process directly. Zeolite, as an important type of solid acid catalyst, has a unique pore structure, adjustable acidity, and good thermal stability. It can promote the efficient cracking and conversion of heavy oil molecules, reduce coke formation, and improve the yield and quality of light oil products. This paper systematically reviews the development status of heavy oil cracking technology, focusing on the structural characteristics, acidity regulation of zeolite catalysts, and their applications in heavy oil cracking and hydrocracking. The mechanism of the cracking reaction of polycyclic aromatic hydrocarbons and long-chain alkanes is analyzed in detail, and the catalytic characteristics and modification methods of zeolite in the reaction process are explained. In addition, this paper summarizes the main challenges faced by zeolite catalysts in practical applications, including uneven acidity distribution, limited pore diffusion, and easy catalyst deactivation, and proposes targeted development strategies. Finally, this paper looks forward to the future development direction of zeolite catalysts in the field of heavy oil cracking and upgrading reactions, emphasizes the importance of structural optimization and multi-scale characterization, and provides theoretical support and practical reference for the design and industrial application of efficient zeolite catalysts. Full article

(This article belongs to the Section Catalytic Materials)

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21 pages, 6034 KB

Open AccessEditor’s ChoiceArticle

Silver-Modified Biochar: Investigating NO₂ Adsorption and Reduction Efficiency at Different Temperatures

by Flavia Tavares, Fernanda F. Camilo, Mohamed Zbair, Lionel Limousy and Jocelyne Brendle

Catalysts 2025, 15(4), 392; https://doi.org/10.3390/catal15040392 - 17 Apr 2025

Cited by 1 | Viewed by 1163

Abstract

This study investigates the adsorption and reduction of NO₂ on biochar (BCC) and silver-modified biochar (Ag-BCC) in a continuous flow. Ag-BCC showed a higher NO₂ adsorption capacity (11.78 mg/g) than BCC (11.04 mg/g) at 200 °C, despite its lower surface area [...] Read more.

This study investigates the adsorption and reduction of NO₂ on biochar (BCC) and silver-modified biochar (Ag-BCC) in a continuous flow. Ag-BCC showed a higher NO₂ adsorption capacity (11.78 mg/g) than BCC (11.04 mg/g) at 200 °C, despite its lower surface area (345 vs. 402 m²/g). While neither material decomposed NO₂ at 22 °C, Ag-BCC achieved a NO/NO₂ ratio of 20% (vs. 9% for BCC) at 200 °C, highlighting the catalytic role of silver in NO₂ conversion. Breakthrough curve modeling identified the Dose–Response model as optimal, accurately describing adsorption kinetics at all temperatures (22–200 °C). Adsorption rate constants decreased with increasing temperature, confirming exothermicity. Overall, the results highlight the enhanced performance of Ag-BCC for NO₂ capture and conversion, underlining the potential of surface-modified biochars in the sustainable mitigation of air pollution. Full article

(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Biomass Catalytic Conversion)

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16 pages, 3060 KB

Open AccessEditor’s ChoiceArticle

High-Pressure CO₂ Photoreduction, Flame Spray Pyrolysis and Type-II Heterojunctions: A Promising Synergy

by Matteo Tommasi, Alice Gramegna, Simge Naz Degerli, Federico Galli and Ilenia Rossetti

Catalysts 2025, 15(4), 383; https://doi.org/10.3390/catal15040383 - 16 Apr 2025

Viewed by 901

Abstract

In this work, three catalysts, TiO₂, WO₃ and TiO₂/WO₃, have been synthesized through flame spray pyrolysis synthesis (FSP) and have been tested for CO₂ photoreduction. The catalysts were fully characterized by XRD, DRS UV–Vis, N [...] Read more.

In this work, three catalysts, TiO₂, WO₃ and TiO₂/WO₃, have been synthesized through flame spray pyrolysis synthesis (FSP) and have been tested for CO₂ photoreduction. The catalysts were fully characterized by XRD, DRS UV–Vis, N₂ physisorption and SEM. Experimental tests were performed in a one-of-a-kind high-pressure reactor at 18 bar. TiO₂ P25 was used as a benchmark to compare the productivities of the newly synthetized catalysts. The two single oxides showed comparable productivities, both slightly lower than the P25 reference value (ca. 17 mol/kg_cat·h). The mixed oxide, TiO₂/WO₃, instead showed an impressive productivity of formic acid with 36 mol/kg_cat·h, which is around 2.5 times higher than both of the single oxides alone. The formation of a type-II heterojunction has been confirmed through DRS analysis. The remarkable productivity demonstrates how FSP synthesis can be a crucial tool to obtain highly active and stable photocatalysts. This approach has already been successfully scaled up for the industrial production of various catalysts, showcasing its versatility and efficiency. Full article

(This article belongs to the Special Issue Advances in Catalysis for a Sustainable Future)

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16 pages, 1696 KB

Open AccessEditor’s ChoiceReview

Recent Advances in the Engineering of Cytochrome P450 Enzymes

by Chang Liu and Xi Chen

Catalysts 2025, 15(4), 374; https://doi.org/10.3390/catal15040374 - 11 Apr 2025

Cited by 2 | Viewed by 4904

Abstract

Cytochrome P450 enzymes (CYPs) are versatile heme-containing monooxygenases involved in the metabolism of endogenous and exogenous compounds, as well as natural product biosynthesis. Their ability to catalyze regio- and stereoselective oxidation reactions makes them valuable in pharmaceuticals, fine chemicals, and biocatalysis. However, wild-type [...] Read more.

Cytochrome P450 enzymes (CYPs) are versatile heme-containing monooxygenases involved in the metabolism of endogenous and exogenous compounds, as well as natural product biosynthesis. Their ability to catalyze regio- and stereoselective oxidation reactions makes them valuable in pharmaceuticals, fine chemicals, and biocatalysis. However, wild-type CYPs suffer from low catalytic efficiency, limited substrate specificity, and instability under industrial conditions. Recent advances in protein engineering—rational design, semi-rational design, and directed evolution—have enhanced their activity, stability, and substrate scope. These strategies have enabled CYPs to be engineered for applications like C–H functionalization, carbene transfer, and complex molecule biosynthesis. Despite progress, challenges remain in optimizing efficiency, expanding substrate ranges, and scaling production for industrial use. Future directions include integrating CYPs with other biocatalysts, improving high-throughput screening, and applying machine learning to enzyme design. This review highlights recent developments and the promising future of engineered CYPs in sustainable chemistry, drug development, and high-value chemical production. Full article

(This article belongs to the Special Issue Enzyme Engineering—the Core of Biocatalysis)

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18 pages, 3255 KB

Open AccessEditor’s ChoiceArticle

Heterogeneous Acid Catalytic Filaments for Three-Dimensional Printing: Their Preparation, Characterization, and Reduction of Free Fatty Acids in Crude Palm Oil

by Jarernporn Thawornprasert, Kritsakon Pongraktham and Krit Somnuk

Catalysts 2025, 15(4), 356; https://doi.org/10.3390/catal15040356 - 5 Apr 2025

Viewed by 1889

Abstract

This study focuses on the fabrication and application of heterogeneous acid catalytic filaments for free fatty acid (FFA) reduction in crude palm oil (CPO) via esterification. Amberlyst-15 catalyst was blended with acrylonitrile butadiene styrene (ABS) using a single-screw filament extruder to produce Amberlyst-15/ABS [...] Read more.

This study focuses on the fabrication and application of heterogeneous acid catalytic filaments for free fatty acid (FFA) reduction in crude palm oil (CPO) via esterification. Amberlyst-15 catalyst was blended with acrylonitrile butadiene styrene (ABS) using a single-screw filament extruder to produce Amberlyst-15/ABS catalytic filaments. A 5 wt.% concentration of fine Amberlyst-15 particles was considered optimal for blending with ABS, making them a suitable acid catalyst for FFA reduction. The mechanical properties, thermal behavior, and morphology of the Amberlyst-15/ABS catalytic filaments were assessed. The esterification process was optimized by varying three independent variables: the methanol-to-oil molar ratio, catalytic filament loading, and reaction time. The results revealed that under the recommended conditions—26.7:1 methanol-to-oil molar ratio, 78.5 wt.% catalytic filament loading, and a reaction time of 20.2 h at 500 rpm and 60 °C—the FFA content in CPO was reduced from 10.05 to 0.83 wt.%. Additionally, the reusability of the catalytic filaments was evaluated under the recommended conditions of the esterification process. The results demonstrated that the filaments remained effective for at least two cycles, achieving FFA levels below 2 wt.%, thereby confirming their stability and catalytic efficiency. The methodology employed in this study for the preparation and characterization of Amberlyst-15/ABS catalytic filaments offers a promising approach for fabricating acid catalytic materials via 3D printing, especially for heterogeneous catalysis in esterification reactions. Full article

(This article belongs to the Section Industrial Catalysis)

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9 pages, 2547 KB

Open AccessEditor’s ChoiceArticle

Correlation Between the Apparent Rate Constant and the Dye Concentration—Effect of the Bottom Reflection Ability on the Photocatalytic Reaction Rate

by Emil Lilov, Svetlozar Nedev, Vanya Lilova, Christian Girginov and Stephan Kozhukharov

Catalysts 2025, 15(4), 347; https://doi.org/10.3390/catal15040347 - 2 Apr 2025

Viewed by 923

Abstract

The dependence of the reaction rate on the solution layer thickness discovered in a previous work could be a powerful tool for investigating photocatalytic reactions. A reduction of the apparent rate constant with the growth of the dye concentration was found using this [...] Read more.

The dependence of the reaction rate on the solution layer thickness discovered in a previous work could be a powerful tool for investigating photocatalytic reactions. A reduction of the apparent rate constant with the growth of the dye concentration was found using this dependence. This decrement follows a hyperbolic law. This dependence is explained based on the observed increment of the solution conductivity. In addition, it is confirmed experimentally that the reaction rate decreases with the solution depth growth. The possibility of independent determination of the reaction rate constant and the adsorption equilibrium constant has been discussed. Additionally, it is demonstrated that the vessel’s reflective bottom could increase the chemical reaction rate. The reason why other authors have not yet reported this effect is also discussed. Full article

(This article belongs to the Section Photocatalysis)

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21 pages, 4523 KB

Open AccessFeature PaperEditor’s ChoiceArticle

ZIF-67-Derived Co−N−C Supported Ni Nanoparticles as Efficient Recyclable Catalyst for Hydrogenation of 4-Nitrophenol

by Juti Rani Deka, Diganta Saikia, Jia-Cheng Lin, Wan-Yu Chen, Hsien-Ming Kao and Yung-Chin Yang

Catalysts 2025, 15(4), 343; https://doi.org/10.3390/catal15040343 - 1 Apr 2025

Cited by 2 | Viewed by 1901

Abstract

In this study, a novel, highly efficient, environment friendly, and low-cost nanocatalyst, denoted as Ni(x)@Co−N−C, was successfully developed by encapsulating Ni nanoparticles into N-doped porous carbon derived from ZIF-67. A variety of techniques including powder X-ray diffraction (XRD), nitrogen adsorption/desorption, scanning electron microscopy [...] Read more.

In this study, a novel, highly efficient, environment friendly, and low-cost nanocatalyst, denoted as Ni(x)@Co−N−C, was successfully developed by encapsulating Ni nanoparticles into N-doped porous carbon derived from ZIF-67. A variety of techniques including powder X-ray diffraction (XRD), nitrogen adsorption/desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrometer (XPS) were used to characterize the prepared materials. The TEM images reveal that the nanoparticles were distributed homogeneously in the carbon support. The N atoms in the carbon support serve as the sites for the nucleation and uniform growth of Ni nanoparticles. The catalyst was used for the degradation of environmentally harmful 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Among all the catalysts investigated, Ni(10)@Co-N-C exhibited the highest catalytic activity for the hydrogenation of 4-NP, with a specific reaction rate of 6.1 × 10⁻³ s⁻¹, activity parameter of 31 s⁻¹g⁻¹, and turn over frequency (TOF) of 1.78 × 10¹⁹ molecules g_metal⁻¹s⁻¹. On the other hand, the specific reaction rate and TOF value were 1.7 × 10⁻³ s⁻¹ and 6.96 × 10¹⁸ molecules g_metal⁻¹s⁻¹, respectively, for Co−N−C. This suggests that Ni(10)@Co−N−C is about three times more catalytically active than the Co−N−C catalyst. The superb activity of Ni(10)@Co−N−C in comparison to Co−N−C can be ascribed to the homogeneous dispersion of small-sized Ni nanoparticles, the interconnected three-dimensional porous arrangement of the support Co−N−C, the presence of N atoms in the carbon framework that stabilize metal nanoparticles, and the synergistic electronic effect between Ni and Co. The Ni(10)@Co−N−C catalyst maintained consistent catalytic activity over multiple cycles, which suggests that porous N-containing carbon support can effectively prevent aggregation and leaching of metal nanoparticles. The ICP-AES analysis of the recycled Ni(10)@Co−N−C revealed a slight reduction in metal content compared to the fresh sample, suggesting almost negligible leaching of metal nanoparticles. Full article

(This article belongs to the Special Issue Nanocatalysts for Degradation of Environmental Pollutants and Hydrogen Generation)

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20 pages, 4861 KB

Open AccessEditor’s ChoiceArticle

Improving the Catalytic Selectivity of Reverse Water–Gas Shift Reaction Catalyzed by Ru/CeO₂ Through the Addition of Yttrium Oxide

by Alfredo Solís-García, Karina Portillo-Cortez, David Domínguez, Sergio Fuentes-Moyado, Jorge N. Díaz de León, Trino A. Zepeda and Uriel Caudillo-Flores

Catalysts 2025, 15(4), 301; https://doi.org/10.3390/catal15040301 - 23 Mar 2025

Cited by 1 | Viewed by 1956

Abstract

This study reports the synthesis, characterization, and catalytic performance of a series of catalysts of Ru supported on CeO₂-Y₂O₃ composites (Ru/CeYX; X = 0, 33, 66, and 100 wt.% Y₂O₃) for CO₂ hydrogenation. [...] Read more.

This study reports the synthesis, characterization, and catalytic performance of a series of catalysts of Ru supported on CeO₂-Y₂O₃ composites (Ru/CeYX; X = 0, 33, 66, and 100 wt.% Y₂O₃) for CO₂ hydrogenation. Supported material modification (Y₂O₃-CeO₂), by the Y₂O₃ incorporation, allowed a change in selectivity from methane to RWGS of the CO₂ hydrogenation reaction. This change in selectivity is correlated with the variation in the physicochemical properties caused by Y₂O₃ addition. X-ray diffraction (XRD) analysis confirmed the formation of crystalline fluorite-phase CeO₂ and α-Y₂O₃. High-resolution transmission electron microscopy (HR-TEM) and energy-dispersive X-ray spectroscopy (EDS) elemental mapping revealed the formation of a homogeneous CeO₂-Y₂O₃ nanocomposite. As the Y₂O₃ content increased, the specific surface area, measured by BET, showed a decreasing trend from 106.3 to 51.7 m² g⁻¹. X-ray photoelectron spectroscopy (XPS) of Ce3d indicated a similar Ce³⁺/Ce⁴⁺ ratio across all CeO₂-containing materials, while the O1s spectra showed a reduction in oxygen vacancies with increasing Y₂O₃ content, which is attributed to the decreased surface area upon composite formation. Catalytically, the addition of Y₂O₃ influenced both conversion and selectivity. CO₂ conversion decreased with increasing Y₂O₃ content, with the lowest conversion observed for Ru/CeY100. Regarding selectivity, methane was the dominant product for Ru/CeY0 (pure CeO₂), while CO was the main product for Ru/CeY33, Ru/CeY66, and Ru/CeY100, indicating a shift towards the reverse water–gas shift (RWGS) reaction. The highest RWGS reaction rate was observed with the Ru/CeY33 catalyst under all tested conditions. The observed differences in conversion and selectivity are attributed to a reduction in active sites due to the decrease in surface area and oxygen vacancies, both of which are important for CO₂ adsorption. In order to verify the surface species catalytically active for RWGS, the samples were characterized by FTIR spectroscopy under reaction conditions. Full article

(This article belongs to the Special Issue Design and Synthesis of Nanostructured Catalysts, 2nd Edition)

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22 pages, 8771 KB

Open AccessEditor’s ChoiceArticle

Controlled Synthesis of Nickel Phosphides in Hollow N, P Co-Doped Carbon: In Situ Transition to (Oxy)hydroxide Phases During Oxygen Evolution Reaction

by David Ríos-Ruiz, Pablo Arévalo-Cid, Jesús Cebollada, Verónica Celorrio, Miran Čeh, Sandra Drev and María Victoria Martínez-Huerta

Catalysts 2025, 15(3), 292; https://doi.org/10.3390/catal15030292 - 20 Mar 2025

Cited by 1 | Viewed by 1985

Abstract

Developing sustainable and efficient electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing energy storage technologies. This study explored the dual role of phosphorus as a dopant in carbon matrices and a key component in nickel phosphides (Ni₂P and [...] Read more.

Developing sustainable and efficient electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing energy storage technologies. This study explored the dual role of phosphorus as a dopant in carbon matrices and a key component in nickel phosphides (Ni₂P and Ni₁₂P₅), synthesized using dopamine (PDA) and ammonium phosphate as eco-friendly precursors. The phase formation of nickel phosphides was found to be highly dependent on the P/PDA ratio (0.15, 0.3, 0.6, and 0.9), allowing for the selective synthesis of Ni₂P or Ni₁₂P₅. Operando Raman spectroscopy revealed that both phases undergo surface transformation into nickel (oxy)hydroxide species under OER conditions, yet Ni₂P-based catalysts demonstrated superior activity and long-term stability. This enhancement is attributed to efficient electron transfer at the dynamic Ni₂P/NiOOH interface. Additionally, hollow nanostructures formed at intermediate P/PDA ratios (≤0.3) via the Kirkendall effect and Ostwald ripening contributed to an increased specific surface area and micropore volume, further improving the catalytic performance. Electrochemical impedance spectroscopy confirmed reduced interfacial resistance and enhanced charge transport. These findings offer new insights into the rational design of high-performance electrocatalysts and propose a green, tunable synthesis approach for advanced energy conversion applications. Full article

(This article belongs to the Special Issue Recent Advances in Electrocatalysis and Future Perspective)

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23 pages, 5288 KB

Open AccessFeature PaperEditor’s ChoiceReview

A Review on Green Hydrogen Production by Aqueous Phase Reforming of Lignocellulose and Derivatives

by Mengjie Li, Weilong Ji, Chunjie Huang, Xiaoqin Si, Qian Liu, Rui Lu and Tianliang Lu

Catalysts 2025, 15(3), 280; https://doi.org/10.3390/catal15030280 - 17 Mar 2025

Cited by 3 | Viewed by 2355

Abstract

With the intensification of the global energy crisis, hydrogen has attracted significant attention as a high-energy-density and zero-emission clean energy source. Traditional hydrogen production methods are dependent on fossil fuels and simultaneously contribute to environmental pollution. The aqueous phase reforming (APR) of renewable [...] Read more.

With the intensification of the global energy crisis, hydrogen has attracted significant attention as a high-energy-density and zero-emission clean energy source. Traditional hydrogen production methods are dependent on fossil fuels and simultaneously contribute to environmental pollution. The aqueous phase reforming (APR) of renewable biomass and its derivatives has emerged as a research hotspot in recent years due to its ability to produce green hydrogen in an environmentally friendly manner. This review provides an overview of the advancements in APR of lignocellulosic biomass as a sustainable and environmentally friendly method for hydrogen production. It focuses on the reaction pathways of various biomass feedstocks (such as glucose, cellulose, and lignin), as well as the types and performance of catalysts used in the APR process. Finally, the current challenges and future prospects in this field are briefly discussed. Full article

(This article belongs to the Special Issue Plant-Derived Biomass Catalytic and Biocatalytic Transformation into Biorefinery Products)

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22 pages, 3017 KB

Open AccessFeature PaperEditor’s ChoiceReview

Advances in the Enzymatic Synthesis of Nucleoside-5′-Triphosphates and Their Analogs

by Maryke Fehlau, Sarah Westarp, Peter Neubauer and Anke Kurreck

Catalysts 2025, 15(3), 270; https://doi.org/10.3390/catal15030270 - 13 Mar 2025

Cited by 2 | Viewed by 4610

Abstract

Nucleoside-5′-triphosphates (5′-NTPs) are essential building blocks of nucleic acids in nature and play an important role in molecular biology, diagnostics, and mRNA therapeutic synthesis. Chemical synthesis has long been the standard method for producing modified 5′-NTPs. However, chemical routes face limitations, including low [...] Read more.

Nucleoside-5′-triphosphates (5′-NTPs) are essential building blocks of nucleic acids in nature and play an important role in molecular biology, diagnostics, and mRNA therapeutic synthesis. Chemical synthesis has long been the standard method for producing modified 5′-NTPs. However, chemical routes face limitations, including low regio- and stereoselectivity, along with the need for protection/deprotection cycles, resulting in low yields, high costs, and lengthy processes. In contrast, enzymatic synthesis methods offer significant advantages, such as improved regio- and stereoselectivity and the use of mild reaction conditions, which often leads to higher product yields in “one-pot” reactions. Despite the extensive review of chemical synthesis routes for 5′-NTPs, there has not yet been any comprehensive analysis of enzymatic approaches. Initially, this review provides a brief overview of the enzymes involved in nucleotide metabolism, introducing valuable biocatalysts for 5’-NTP synthesis. Furthermore, the available enzymatic methods for efficient 5′-NTP synthesis using purified enzymes and starting from either nucleobases or nucleosides are examined, highlighting their respective advantages and disadvantages. Special attention is also given to the importance of ATP regeneration systems for 5′-NTP synthesis. We aim to demonstrate the remarkable potential of enzymatic in vitro cascade reactions, promoting their broader application in both basic research and industry. Full article

(This article belongs to the Special Issue Feature Papers in Catalysis for Pharmaceuticals)

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25 pages, 1912 KB

Open AccessFeature PaperEditor’s ChoiceReview

A Review of Materials for Carbon Dioxide Capture

by Ashish Rana and Jean M. Andino

Catalysts 2025, 15(3), 273; https://doi.org/10.3390/catal15030273 - 13 Mar 2025

Cited by 12 | Viewed by 7589

Abstract

The increasing concentration of carbon dioxide (CO₂) in the atmosphere is a significant contributor to global warming and climate change. Effective CO₂ capture and storage technologies are critical to mitigating these impacts. This review explores various materials used for CO [...] Read more.

The increasing concentration of carbon dioxide (CO₂) in the atmosphere is a significant contributor to global warming and climate change. Effective CO₂ capture and storage technologies are critical to mitigating these impacts. This review explores various materials used for CO₂ capture, focusing on the latest advancements and their applications. The review categorizes these materials into chemical and physical absorbents, highlighting their unique properties, advantages, and limitations. Chemical absorbents, such as amine-based solutions and hydroxides, have been widely used due to their high CO₂ absorption capacities and established technological frameworks. However, they often suffer from high energy requirements for regeneration and potential degradation over time. Recent developments in ionic liquids (ILs) and polymeric ionic liquids (PILs) offer promising alternatives, providing tunable properties and lower regeneration energy. Physical absorbents, including advanced solvents like nanofluids and ionic liquids as well as industrial processes like selexol, rectisol, and purisol, demonstrate enhanced CO₂ capture efficiency under various conditions. Additionally, adsorbents like activated carbon, zeolites, metal-organic frameworks (MOFs), carbon nanotubes (CNTs), and layered double hydroxides (LDHs) play a crucial role by providing high surface areas and selective CO₂ capture through physical or chemical interactions. This paper summarizes the state of research on different materials and discusses their advantages and limitations while being used in CO₂ capture technologies. This review also discussed multiple studies examining the use of catalysts and absorption mechanisms in combination with different sorbents, focusing on how these approaches enhance the efficiency of absorption and desorption processes. Through a comprehensive analysis, this review aims to provide valuable insights into the type of materials that are most suitable for CO₂ capture and also provides directions for future research in this area. Full article

(This article belongs to the Special Issue Feature Review Papers in Catalysis for Sustainable Energy)

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17 pages, 28408 KB

Open AccessEditor’s ChoiceArticle

Immobilization of Enzymes on Electrodes and Electrode Design in Biofuel Cells

by Chang Yen Chen, Adama A. Bojang, Damayanti Damayanti and Ho Shing Wu

Catalysts 2025, 15(3), 253; https://doi.org/10.3390/catal15030253 - 6 Mar 2025

Cited by 1 | Viewed by 1783

Abstract

In an enzyme-based fuel cell system, glucose oxidase and laccase were immobilized on carbon paper as the anode and cathode electrodes. A conductive polymer (polypyrrole) was added to improve conductivity. The mediator and enzymes were mixed in a phosphate-buffer solution for entrapment. A [...] Read more.

In an enzyme-based fuel cell system, glucose oxidase and laccase were immobilized on carbon paper as the anode and cathode electrodes. A conductive polymer (polypyrrole) was added to improve conductivity. The mediator and enzymes were mixed in a phosphate-buffer solution for entrapment. A Nafion 212 membrane separated the two half-cells. Power density measurements were taken at a glucose concentration of 10 mM across different operating voltages. Potassium hexacyanoferrate III was used as a redox mediator in the anode and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) in the cathode to boost power output. The biofuel cells, constructed from acrylic (40 × 50 × 50 mm) with a working volume of 20 × 30 × 40 mm, were assembled using a rubber gasket to secure the Nafion membrane. The use of micropore tape covering the electrodes extended the system’s operational lifespan. Without the micropore tape, the maximum power density was 57.6 μW/cm² at 0.24 V. With the micropore tape, the cell achieved a maximum power density of 324.9 μW/cm² at 0.57 V, sustaining performance for 20 days. Thus, micropore tape effectively enhances enzyme retention and biofuel cell performance. Full article

(This article belongs to the Special Issue Enzyme and Biocatalysis Application)

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14 pages, 6301 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Photocatalytic Cement Mortar with Durable Self-Cleaning Performance

by Zhuoying Jiang, Bin Zhang and Xiong Yu

Catalysts 2025, 15(3), 249; https://doi.org/10.3390/catal15030249 - 6 Mar 2025

Cited by 2 | Viewed by 1959

Abstract

Nano-TiO₂-modified mortars are fabricated by introducing TiO₂ nanoparticles to the conventional mortar mix with designed mixing and curing procedures. It was found that additional TiO₂ nanoparticles can accelerate hydration and improve the air void distribution in the mortar matrix. [...] Read more.

Nano-TiO₂-modified mortars are fabricated by introducing TiO₂ nanoparticles to the conventional mortar mix with designed mixing and curing procedures. It was found that additional TiO₂ nanoparticles can accelerate hydration and improve the air void distribution in the mortar matrix. The experiments also showed that 0.5 wt.% and 1 wt.% TiO₂-modified mortar has a comparable mechanical strength to traditional cement mortar. The abrasion resistance is improved with nanoparticles at 0.5 wt.% TiO₂ concentration. The photocatalytic performance of photocatalytic mortar was confirmed by a methylene blue decomposition test. Finally, a multi-physics computational model was constructed to assess the effects of photocatalytic mortar coated on building in air quality improvements in the neighboring area. The benefits are affected by different nano-TiO₂ concentrations, as well as wind conditions in the neighborhood. Overall, this study shows that properly designed nano-TiO₂-modified mortar is promising to achieve multifunctional performance in terms of mechanical strength and durability as well as autogenous self-cleaning of surrounding environment. Full article

(This article belongs to the Special Issue TiO₂ Photocatalysts: Design, Optimization and Application)

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Open AccessEditor’s ChoiceReview

Catalytic Properties and Structural Optimization of Solid Transesterification Catalysts to Enhance the Efficiency of Biodiesel Synthesis

by Xiangyang Li, Siwei Zhang, Xunxiang Jia, Weiji Li and Jiliang Song

Catalysts 2025, 15(3), 239; https://doi.org/10.3390/catal15030239 - 1 Mar 2025

Cited by 7 | Viewed by 4554

Abstract

The transition to sustainable energy has given biodiesel prominence as a renewable alternative to diesel. This review highlights the development and optimization of solid transesterification catalysts, contributing greatly to the efficiency of biodiesel synthesis. These heterogeneous catalysts are constituted of titanium-, zinc-, and [...] Read more.

The transition to sustainable energy has given biodiesel prominence as a renewable alternative to diesel. This review highlights the development and optimization of solid transesterification catalysts, contributing greatly to the efficiency of biodiesel synthesis. These heterogeneous catalysts are constituted of titanium-, zinc-, and bio-based systems and significant advantages such as reusability, thermal stability, and the ability to be synthesized from low-grade feedstocks. Recent advancements in structural optimization, with nano-structured titanium dioxide having the potential of yielding higher biodiesel production up to a yield of 96–98% within 5–7 cycles, render improved stability and catalytic performance. Several characterization techniques, such as the Brunauer–Emmett–Teller method, X-ray diffraction, and temperature-programmed desorption, are instrumental in the characterization of these catalysts and their effective design. However, despite their substantial promise, there are still problems to be dealt with in the large-scale production, regeneration, and service life stability of these catalysts. This account collates recent innovations, analytical mechanisms, and prospective directions which elucidate the potential of solid transesterification catalysts in furthering biodiesel technology and the sustainable production of chemicals. Full article

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