Catalysts

30 pages, 5293 KB

Open AccessFeature PaperArticle

High-Performance Metal-Free Nitrogen-Doped Carbon Catalyst Derived from Polyurea–Polyimine Copolymer for Anion Exchange Membrane Fuel Cells

by Fu-Lung Lin, Che-Ju Tseng and Ko-Shan Ho

Catalysts 2026, 16(6), 573; https://doi.org/10.3390/catal16060573 - 22 Jun 2026

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Abstract

Developing cost-effective alternatives to platinum-based catalysts remains paramount for commercializing anion exchange membrane fuel cells (AEMFCs). We report a metal-free nitrogen-doped carbon catalyst derived from a rationally designed polyurea–polyimine copolymer that outperforms commercial 20 wt% Pt/C in superior relative durability and methanol tolerance. [...] Read more.

Developing cost-effective alternatives to platinum-based catalysts remains paramount for commercializing anion exchange membrane fuel cells (AEMFCs). We report a metal-free nitrogen-doped carbon catalyst derived from a rationally designed polyurea–polyimine copolymer that outperforms commercial 20 wt% Pt/C in superior relative durability and methanol tolerance. Strategic integration of polyurea’s pore-forming capability with polyimine’s thermal stability enabled the synthesis of a catalyst (NC-1000N) featuring ultrahigh surface area (1276.5 m² g⁻¹), optimal nitrogen speciation (20.5% pyridinic-N, 45.3% graphitic-N), and enhanced graphitization, which improves the electrical conductivity of catalysts. NC-1000N exhibited exceptional oxygen reduction performance with an onset potential of 0.96 V, almost four-electron selectivity (n = 3.87), a medium Tafel slope (105 mV dec⁻¹), and minimal charge transfer resistance (46.74 Ω). When evaluated in single-cell AEMFCs, NC-1000N delivered a peak power density of 372.1 mW cm⁻², which is 26% higher than Pt/C at equivalent loading, while demonstrating superior stability (94.8% retention after 7 h) and complete methanol tolerance. Systematic pyrolysis temperature optimization (800–1000 °C) revealed critical structure–property relationships governing catalyst evolution from disordered precursor to highly graphitic, nitrogen-enriched carbon with precisely engineered active sites. This work establishes polymer-derived carbons and provides design principles for scalable synthesis of high-performance metal-free electrocatalysts for sustainable energy conversion technologies. Full article

(This article belongs to the Special Issue Catalytic Materials in Electrochemical and Fuel Cells)

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20 pages, 5055 KB

Open AccessArticle

Comprehensive Evaluation of Antioxidant and Multi-Enzyme Inhibitory Effects of Coniferyl Alcohol and Coniferyl Aldehyde: Insights from Molecular Docking

by Eda Mehtap Özden, Hatice Kızıltaş and İlhami Gulcin

Catalysts 2026, 16(6), 572; https://doi.org/10.3390/catal16060572 - 22 Jun 2026

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Abstract

Coniferyl alcohol and coniferyl aldehyde are precursors of lignin and are used in spices and the pharmaceutical industry. In this work, antioxidant, anticholinergic, antidiabetic, and antiglaucoma effects of coniferyl alcohol and aldehyde were evaluated and compared against the standards. To determine the antioxidant [...] Read more.

Coniferyl alcohol and coniferyl aldehyde are precursors of lignin and are used in spices and the pharmaceutical industry. In this work, antioxidant, anticholinergic, antidiabetic, and antiglaucoma effects of coniferyl alcohol and aldehyde were evaluated and compared against the standards. To determine the antioxidant capacities of coniferyl alcohol and aldehyde, ABTS^•+, DMPD^•+ and DPPH^• scavenging abilities as well as cupric ion (Cu²⁺) reduction, ferrous ions (Fe²⁺) reduction and Fe³⁺-TPTZ reduction activities were studied. Butylated hydroxytoluene (BHT), ascorbic acid, α-Tocopherol, Trolox, and butylated hydroxyanisole (BHA) were used as the standard antioxidants. When the antioxidant effects of coniferyl alcohol and coniferyl aldehyde are compared to the standards, they exhibit significant antioxidant effects. In addition, it was determined that coniferyl alcohol and coniferyl aldehyde had a high degree of inhibition effect towards carbonic anhydrase (hCA) I and II isoforms purified from human erythrocytes, α-glycosidase, butyrylcholinesterase (BChE), acetylcholinesterase (AChE), and α-amylase as in vitro and in silico. Molecular docking studies revealed favorable binding affinities of coniferyl alcohol and coniferyl aldehyde toward all investigated enzymes, with key hydrogen bonding and π–π interactions identified at the active sites. The docking findings were found to be compatible with the in vitro enzyme inhibition results, supporting the proposed multi-target biological potential of both compounds. Molecular docking studies revealed favorable binding affinities of coniferyl alcohol and coniferyl aldehyde toward all investigated enzymes. Key hydrogen bonding and π–π interactions were identified within the active sites, particularly for AChE and hCA II. The docking results were consistent with the in vitro enzyme inhibition data, supporting their multi-target biological potential. Docking demonstrated that both compounds can effectively interact with the catalytic regions of the target enzymes. The identified binding modes and interaction patterns support the observed inhibitory activities and provide a molecular basis for their multi-target biological effects. Full article

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

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15 pages, 2319 KB

Open AccessArticle

Structural Preorganization in Clamp-Shaped Dihydrogen-Bonded Iodide Catalysts for Efficient CO₂ Cycloaddition Under Atmospheric Pressure

by Ziyun Zhang, Lisi Yuan, Liwenze He, Shike Liu, Min Zhou, Zhihang Xiong and Dengpeng Song

Catalysts 2026, 16(6), 571; https://doi.org/10.3390/catal16060571 - 21 Jun 2026

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Abstract

The rational design of metal-free catalysts capable of efficiently converting CO₂ under atmospheric pressure remains a significant challenge in sustainable chemistry. Herein, we report a series of clamp-shaped dihydrogen-bonded iodide catalysts (CDBI catalysts) featuring a preorganized bifunctional framework that integrates dual hydrogen-bond [...] Read more.

The rational design of metal-free catalysts capable of efficiently converting CO₂ under atmospheric pressure remains a significant challenge in sustainable chemistry. Herein, we report a series of clamp-shaped dihydrogen-bonded iodide catalysts (CDBI catalysts) featuring a preorganized bifunctional framework that integrates dual hydrogen-bond donors and an intrinsic iodide nucleophile within a single molecular scaffold. Systematic structural variation revealed that catalytic activity is highly sensitive to electronic modulation, steric accessibility, and precise spatial arrangement between the hydrogen-bonding units and the iodide center. The optimal catalyst enabled solvent-free cycloaddition of CO₂ with epoxides at 1 atm CO₂, affording up to 99% conversion and >99% selectivity at 80 °C within 12 h. Substrate scope studies demonstrated efficient transformation of a wide range of terminal epoxides, while sterically demanding substrates exhibited reduced reactivity consistent with a confined activation mode. Mechanistic investigations support a cooperative pathway in which dual hydrogen-bond activation and proximal halide nucleophilicity operate synergistically within a preorganized clamp-shaped pocket. Comparative analysis with representative catalytic systems highlights the ability of this metal-free design to achieve high efficiency under atmospheric CO₂ without cocatalysts or solvents. These findings demonstrate that structural preorganization represents an effective strategy for promoting sustainable CO₂ utilization under operationally simple conditions. Full article

(This article belongs to the Special Issue Advanced Catalysts for CO₂ Capture and Conversion)

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21 pages, 3654 KB

Open AccessFeature PaperArticle

Structure-Activity Relationship of Cu/Activated Carbon Catalysts: Influence of Support Functional Groups and Metal Content on Furfural Conversion

by Catalina Astudillo, Dana Arias, Gina Pecchi, Catherine Sepúlveda, Jorge N. Díaz de León and Carla Herrera

Catalysts 2026, 16(6), 570; https://doi.org/10.3390/catal16060570 - 21 Jun 2026

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Abstract

The influence of carbon support and Cu loading on the structural, surface, and catalytic properties of Cu-based catalysts for furfural hydrogenation was systematically investigated. Two activated carbons with distinct textural and chemical characteristics were evaluated: a biomass-derived carbon (ACS) and commercial carbon (ACC). [...] Read more.

The influence of carbon support and Cu loading on the structural, surface, and catalytic properties of Cu-based catalysts for furfural hydrogenation was systematically investigated. Two activated carbons with distinct textural and chemical characteristics were evaluated: a biomass-derived carbon (ACS) and commercial carbon (ACC). The ACC support exhibited a higher density of thermally stable oxygen-containing functional groups, which promoted stronger metal-support interactions and an increased proportion of surface reduced Cu species (Cu⁰/Cu⁺), resulting in superior catalytic performance compared to ACS. Based on these results, the effect of Cu loading (5–20 wt.%) was further studied on the ACC support. The catalysts were characterized by N₂ physisorption, XRD, TEM, H₂-TPR, He-TPD, NH₃-TPD, and XPS. Increasing Cu loading enhanced the amount and reducibility of Cu species; however, excessive loading led to particle growth, pore blockage, and reduced metal dispersion. Catalytic activity exhibited volcano-type behavior, reaching a maximum at 15 wt.% Cu, where an optimal balance between reduced availability of Cu species and metal-support interaction was achieved. Selectivity toward furfuryl alcohol remained essentially unchanged across all catalysts, indicating that the catalytic performance is closely related to the surface chemistry and relative concentration of reduced Cu sites and is not significantly affected by acidity. These results highlight the critical role of support properties and metal loading in controlling catalyst performance, providing insights for the rational design of efficient Cu-based catalysts for biomass valorization. Full article

(This article belongs to the Special Issue 15th Anniversary of Catalysts—Catalysis for Biomass Conversion and Valorisation)

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25 pages, 1991 KB

Open AccessReview

Bio-Inspired and Enzyme-Mimicking Catalysts for Sustainable Oxidation and Hydrogenation Reactions

by Saeed Vohra, Varun Chauhan, Mohsin Khan, Nadeem Raza and Anis Ahmad Chaudhary

Catalysts 2026, 16(6), 569; https://doi.org/10.3390/catal16060569 - 20 Jun 2026

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Abstract

Demand for greener and safer chemistries has driven the innovation of bioinspired and enzyme-mimicking catalysts for selective and efficient oxidation and hydrogenation under mild conditions. Natural catalysts, including peroxidases, oxidases, hydrogenases, oxygenases and dehydrogenases, boast remarkable activity, specificity, stability, selectivity, low energy requirements [...] Read more.

Demand for greener and safer chemistries has driven the innovation of bioinspired and enzyme-mimicking catalysts for selective and efficient oxidation and hydrogenation under mild conditions. Natural catalysts, including peroxidases, oxidases, hydrogenases, oxygenases and dehydrogenases, boast remarkable activity, specificity, stability, selectivity, low energy requirements and atom economy. Disadvantages of enzymes, such as poor thermal stability, a narrow operational range, low recovery yield and the expense of purification, are motivating the discovery and design of enzyme substitutes. Several artificial platforms have appeared recently: nanozymes, artificial metalloenzymes, biomimetic metal Complexes, MOFs, atomic catalysts, bioinorganic hybrid systems, among others. These systems aim to replicate key structural and mechanistic features of enzymes while providing greater operational stability, recyclability, and scalability. Recent work has demonstrated the benefit of enzyme mimics in increasing eco-sustainability in reactions such as alcohol oxidation, selective alkane oxidation, waste degradation, catalytic photooxygen activation and biomass waste conversion. Similarly, biomimetic hydrogenation catalysts have shown outstanding activity in asymmetrically hydrogenating chemicals, reducing CO₂ into chemicals, hydrogenation by hydrogen transfer and creating hydrogen through water. Through control of active sites, second coordination sites, defects and electrons/protons in the system, significant gains have been seen in reaction selectivity and frequency of turning over substrate into product. Nanozymes, biohybrid catalysis and artificial catalysts guided by deep learning are further broadening the applications of biomimetic catalysis in oxidation and hydrogenation. The article review aims to provide a summary of the most current progress with bioinspired and enzyme-mimicking catalysts, focusing on catalytic mechanisms, how to design such catalysts, how green chemistry benefits from their development and where further application is likely in the coming years. Full article

(This article belongs to the Special Issue Green Catalytic Oxidation and Hydrogenation Routes for Biobased Chemicals Production)

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3 pages, 140 KB

Open AccessEditorial

Environmentally Friendly Catalysis for Green Future

by Zuzeng Qin

Catalysts 2026, 16(6), 568; https://doi.org/10.3390/catal16060568 - 20 Jun 2026

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Abstract

Over the past few decades, the advancement of human society and industrialization has led to severe environmental issues, such as air and water pollution, greenhouse effects, and climate change [...] Full article

(This article belongs to the Special Issue Environmentally Friendly Catalysis for Green Future)

33 pages, 3900 KB

Open AccessReview

Sustainable Ammonia Production, Advances in Electrochemical, Photoelectrochemical, and Photocatalytic Technologies for Green Energy

by Musarat Shahin, Abdul Haseeb Mohsin, Aiman Bibi, Ihtisham Ahmad, Elif Esra Altuner, Ozan Aldemir, Senol Durmusoglu, Mehmet Sabit Yilancilar, Yavuz Tanriverdi, Esra Acar, Busra Akinalan Balik, Ghassan Issa, Muzaffer Elmas and Veli Cengiz Ozalp

Catalysts 2026, 16(6), 567; https://doi.org/10.3390/catal16060567 - 20 Jun 2026

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Abstract

Substantial advances have been made since the 1970s in reducing the environmental impacts of ammonia production. Renewable-driven electrochemical synthesis offers a promising pathway to decarbonize ammonia production. This review examines an integrated route in which hydrogen is generated photoelectrochemically under concentrated solar irradiation [...] Read more.

Substantial advances have been made since the 1970s in reducing the environmental impacts of ammonia production. Renewable-driven electrochemical synthesis offers a promising pathway to decarbonize ammonia production. This review examines an integrated route in which hydrogen is generated photoelectrochemically under concentrated solar irradiation and subsequently used in electrochemical ammonia synthesis. Photoelectrochemical cells are fabricated by electrostatically depositing photosensitive particles onto cathodes to enhance light-driven hydrogen production. Hydrogen production rates and ammonia yield depend strongly on temperature and electrolyte composition. The synthesized hydrogen is fed into a molten salt electrochemical reactor that operates at atmospheric pressure and receives nitrogen from a dedicated supply. This combined solar–electrochemical approach can produce low-carbon ammonia with improved safety and reduced environmental impact, offering a scalable alternative to conventional processes. Full article

(This article belongs to the Special Issue 15th Anniversary of Catalysts: Shaping a Sustainable Future Through Catalysis)

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15 pages, 5174 KB

Open AccessFeature PaperArticle

Ni-Doped Amorphous Al₂O₃ for One-Pot Synthesis of Azoxybenzene via Nitrobenzene Reduction with Sodium Borohydride

by Shuang Wang, Wanying Yang, Rui Zhong, Meiling Zhao, Fengfeng Li, Yuxin Zhou, Wenjuan Shan and Xiujie Li

Catalysts 2026, 16(6), 566; https://doi.org/10.3390/catal16060566 - 19 Jun 2026

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Abstract

Ni-doped amorphous Al₂O₃ catalysts were successfully prepared for the one-step reduction of nitrobenzene to azoxybenzene using NaBH₄ as hydrogen donors under mild conditions. The amorphous Ni₁Al₈₇O_x catalyst achieved a highly efficient azoxybenzene production rate [...] Read more.

Ni-doped amorphous Al₂O₃ catalysts were successfully prepared for the one-step reduction of nitrobenzene to azoxybenzene using NaBH₄ as hydrogen donors under mild conditions. The amorphous Ni₁Al₈₇O_x catalyst achieved a highly efficient azoxybenzene production rate of 1.89 mol·g-Ni⁻¹·h⁻¹, significantly outperforming its Ni/γ-Al₂O₃ counterpart. On the basis of the MAS NMR and XPS characterization results, the enhanced catalytic performance is associated with Ni incorporation during the preparation of amorphous Ni₁Al₈₇O_x, which introduces abundant unsaturated pentacoordinate Al species with oxygen vacancies and stabilizes Ni^δ+ sites against over-reduction. Notably, Ni₁Al₈₇O_x loaded on commercial ZSM-5 supports maintained an azoxybenzene yield of 9.02 mol·g-Ni⁻¹·h⁻¹, highlighting the strong potential for further scalable applications. Full article

(This article belongs to the Special Issue Feature Papers in "Industrial Catalysis" Section, 3rd Edition)

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17 pages, 10167 KB

Open AccessFeature PaperArticle

Synergistic Effects of Ni-Co Alloy Active Sites and Promoter Modification on Nickel-Based Catalysts for Enhanced Performance in Dry Reforming Reactions

by Guopei Zhang, Cong Wang, Xiaoyang Zhang, Zhaomin Li and Leteng Lin

Catalysts 2026, 16(6), 565; https://doi.org/10.3390/catal16060565 - 19 Jun 2026

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Abstract

Dry reforming of methane (DRM) enables the simultaneous conversion of CH₄ and CO₂, yet rapid coking severely restricts the stability of Ni-based catalysts. In this study, Co was incorporated into Ce-, La-, and Zr-promoted Ni catalysts to construct Ni-Co alloy [...] Read more.

Dry reforming of methane (DRM) enables the simultaneous conversion of CH₄ and CO₂, yet rapid coking severely restricts the stability of Ni-based catalysts. In this study, Co was incorporated into Ce-, La-, and Zr-promoted Ni catalysts to construct Ni-Co alloy active sites, and their catalytic behavior was systematically evaluated. While single-promoter modification partially suppressed coke deposition at the expense of activity, Ni-Co alloy formation maintained high reforming performance and significantly enhanced stable catalytic performance within the 20 h evaluation period, with the Ce-promoted Ni-Co catalyst exhibiting the most durable anti-coking performance. CO₂-TPD and coke characterization results indicate that promoter species enhance medium-strength basicity and oxygen mobility, thereby facilitating CO₂ adsorption and accelerating the oxidation of surface coke intermediates; in particular, Ce supplies mobile active oxygen species through its oxygen storage-release capacity. DFT calculations further reveal that Co incorporation modulates the electronic structure of Ni sites, optimizing the balance between CH₄ dissociation and CO₂ activation and thus suppressing excessive methane cracking. These findings elucidate the synergistic effect of Ni-Co alloying and promoter modification in DRM and provide mechanistic insight for the rational design of coke-resistant Ni-based catalysts. Full article

(This article belongs to the Special Issue Advances in Catalysis for Carbon Resource Utilization and Green Chemical Synthesis)

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25 pages, 6416 KB

Open AccessArticle

Comparative Study of Mono- and Bimetallic (Ni–Co–Fe) Catalysts Supported on LaCeO₃ for Ammonia Decomposition

by Seetharamulu Podila, Ahmad Alsobhi, Majed A. Alamoudi and Nagaraju Pasupulety

Catalysts 2026, 16(6), 564; https://doi.org/10.3390/catal16060564 - 18 Jun 2026

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Abstract

Ammonia decomposition over non-precious metal thermos-catalysts offers a viable and cost-effective pathway for sustainable hydrogen production. In this study, LaCeO₃ perovskite was synthesized using a citric acid complexation method and employed as a support for mono- and bimetallic catalysts prepared by incipient [...] Read more.

Ammonia decomposition over non-precious metal thermos-catalysts offers a viable and cost-effective pathway for sustainable hydrogen production. In this study, LaCeO₃ perovskite was synthesized using a citric acid complexation method and employed as a support for mono- and bimetallic catalysts prepared by incipient wetness impregnation, maintaining a total metal loading of 10 wt%. Structural and surface properties were systematically investigated using BET, XRD, H₂-TPR, SEM, TEM, and CO₂-TPD. Among the monometallic catalysts (Ni, Co, and Fe), 10%Ni/LaCeO₃ exhibited the highest activity, which is attributed to its enhanced reducibility and optimal surface basicity, facilitating NH₃ activation. Bimetallic systems (Ni-Co, Ni-Fe, and Co-Fe) with equal metal loadings (5 wt% each) showed better activity compared to their monometallic counterparts following the order: 5%Ni–5%Co/LaCeO₃ > 5%Ni–5%Fe/LaCeO₃ > 5%Co–5%Fe/LaCeO₃. The improved performance of the Ni-Co system is due to structural interactions between Ni and Co, which promote hydrogen desorption and accelerate N–H bond cleavage, while suppressing nitrogen recombination as the rate-limiting step. Further systematic optimization of the Ni/Co ratio showed that 8%Ni–2%Co/LaCeO₃ had the highest catalytic activity with consistent performance over 50 h. This optimal composition provides a balanced distribution of active metallic sites and moderate-to-strong basic sites, enhancing NH₃ adsorption and intermediate transformation. These findings show that LaCeO₃-supported Ni-Co catalysts are promising candidates for efficient hydrogen production from ammonia without using noble metals. Full article

(This article belongs to the Special Issue Catalytic Processes for Green Hydrogen Production)

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21 pages, 19854 KB

Open AccessArticle

Microbubble-Assisted Catalytic Ozonation of Tetracycline-Class Antibiotics Using Granular MIL-101(Fe)/γ-Al₂O₃

by Shuai Wang, Peiyao Chen, Wenqi Cui, Yingning Wang, Xiongwei Liang, Yufeng Zhao and Yang Yang

Catalysts 2026, 16(6), 563; https://doi.org/10.3390/catal16060563 - 18 Jun 2026

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Abstract

Tetracycline-class antibiotics are persistent contaminants in aquatic environments and are difficult to remove by conventional treatment processes. In this study, a recoverable granular MIL-101(Fe)/γ-Al₂O₃ catalyst was prepared through ligand anchoring followed by secondary Fe-MOF growth on spherical γ-Al₂O [...] Read more.

Tetracycline-class antibiotics are persistent contaminants in aquatic environments and are difficult to remove by conventional treatment processes. In this study, a recoverable granular MIL-101(Fe)/γ-Al₂O₃ catalyst was prepared through ligand anchoring followed by secondary Fe-MOF growth on spherical γ-Al₂O₃ and applied to catalytic ozonation of tetracycline (TC) under ordinary-bubble and microbubble-assisted operation. Structural characterization supported the formation of Fe-containing MOF domains on the alumina support, accompanied by an increase in BET surface area from 164.28 to 210.05 m² g⁻¹ and enhanced Lewis-acid-related pyridine-IR signals. Under conventional bubbling ozonation, the optimized catalyst achieved 67.93% apparent UV–Vis-based TC removal during an overall 50 min run consisting of 30 min dark adsorption followed by 20 min ozonation. In a 12 L microbubble reactor, the catalyst-assisted system reached 93.74% apparent UV–Vis-based TC removal at pH 6 with 100 g catalyst and 6 mg min⁻¹ fed ozone, showing higher apparent removal than ordinary ozonation, microbubble ozonation, and ordinary-bubble catalytic ozonation under the tested configuration. Phosphate-blocking and radical-quenching experiments were consistent with the involvement of Lewis-acid-related sites, hydroxyl radicals, and superoxide-related pathways, but these tests are interpreted as indirect mechanistic evidence. LC-MS analysis suggested possible hydroxylation, demethylation, deamidation, ring opening, and low-molecular-weight product formation. The system also transformed chlortetracycline, oxytetracycline, and doxycycline and reduced COD and TOC in a simulated mixed-antibiotic matrix. Because parent-compound HPLC/LC-MS time-series quantification, ozone utilization/off-gas ozone measurement, bubble-size/kLa analysis, and ICP-based Fe loading/leaching data were not available, the present work is positioned as an apparent catalyst–reactor coupling study rather than a complete catalytic, hydrodynamic, or process-level demonstration. Full article

(This article belongs to the Special Issue Advanced Catalysts for Wastewater/Sewage Treatment)

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13 pages, 3001 KB

Open AccessArticle

Nitrogen-Functionalized Graphite Felt for Tetracycline Degradation in Chlorinated Wastewater via Metal-Free Electro-Fenton

by Chaosheng Zhu, Yonghong Zhang, Lin Liu, Zetong Yang, Mingchen Sun, Chao Fan, Yongcai Zhang and Juanjuan Liu

Catalysts 2026, 16(6), 562; https://doi.org/10.3390/catal16060562 - 18 Jun 2026

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Abstract

Traditional electro-Fenton systems for chlorinated antibiotic wastewater suffer from low mineralization, catalyst deactivation, and secondary pollution caused by chloride ions. In this work, nitrogen-functionalized graphite felt cathodes were synthesized by electrodeposition-pyrolysis. Pyridinic N and graphitic N were identified by XPS. The obtained cathodes [...] Read more.

Traditional electro-Fenton systems for chlorinated antibiotic wastewater suffer from low mineralization, catalyst deactivation, and secondary pollution caused by chloride ions. In this work, nitrogen-functionalized graphite felt cathodes were synthesized by electrodeposition-pyrolysis. Pyridinic N and graphitic N were identified by XPS. The obtained cathodes were employed in a metal-free electro-Fenton system for effective tetracycline (TC) removal and mineralization. The results show that the optimal electrode (N-GF-3) achieved 93% degradation efficiency and 73% mineralization of TC in 60 min, when the optimized conditions (pH = 3 and current density = 20 mA/cm²) were employed. Unusually, with the presence of Cl⁻, the system showed even higher catalytic performance, having a degradation kinetic constant 2.4 times higher than that without chloride. The electrode was also reusable, maintaining a TC degradation efficiency above 90% in the fifth cycle. Based on fluorescence analysis of ·OH, a possible dual-path reaction mechanism is proposed. This mechanism provides new insights into designing advanced oxidation processes for the treatment of complex chlorinated organic wastewater. Nevertheless, the potential formation of chlorinated byproducts requires additional investigation. Full article

(This article belongs to the Special Issue Novel Advanced Oxidation Processes for Catalytic Degradation of Emerging Contaminants)

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19 pages, 2502 KB

Open AccessFeature PaperArticle

Transition Metal Single-Atom-Anchored PdN₂ Monolayer for Superior Alkaline Hydrogen Oxidation Reactions

by Yanji Qian, Haoyu Zhang, Wenxi Han, Wenxuan An, Yizhu Wang, Guangkun Yan, Jing Xu and Lianming Zhao

Catalysts 2026, 16(6), 561; https://doi.org/10.3390/catal16060561 - 18 Jun 2026

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Abstract

The sluggish kinetics of alkaline hydrogen oxidation reaction (HOR) and high cost of Pt–based catalysts have long hindered large–scale deployment of alkaline membrane fuel cells. Via first–principles calculations, we designed a series of 3d transition metal single atoms anchored on PdN₂ monolayer [...] Read more.

The sluggish kinetics of alkaline hydrogen oxidation reaction (HOR) and high cost of Pt–based catalysts have long hindered large–scale deployment of alkaline membrane fuel cells. Via first–principles calculations, we designed a series of 3d transition metal single atoms anchored on PdN₂ monolayer (TM–PdN₂, TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and evaluated their alkaline HOR performance. Ti-, Cr-, Fe-, Co-, Ni-modified systems exhibit excellent thermodynamic and electrochemical stability under operating conditions. Single-atom doping tunes the p-band center of N and d-band center of metal sites, enabling precise modulation of H and OH adsorption strengths. Mechanistic analysis reveals HOR follows H₂ + 2OH* → H* + OH* + H₂O → 2H₂O, with the final step as rate-determining step. H adsorption contributes 3.45 times more to HOR activity than OH adsorption. Fe–PdN₂ delivers the best performance, with an ultra–low barrier of 0.11 eV and a rate constant of 2.82 × 10¹⁰ s^–1·site⁻¹, values that significantly outperform those of Pt(111) (0.22 eV, 4.5 × 10⁹ s⁻¹·site⁻¹). This work provides theoretical guidance for rational design of high–performance alkaline HOR electrocatalysts. Full article

(This article belongs to the Special Issue Advanced Catalysis for Sustainable Chemicals and Energy Conversion: Design, Synthesis and Mechanism)

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40 pages, 48656 KB

Open AccessReview

A Review of the Value-Added Conversion of Biomass Catalyzed by High-Entropy Alloys

by Jinyi Lv, Yidong Wang, Hongyu Zhao, Qingrong Li, Jing Sun, Yingping Pang, Xinyan Zhang, Tao Wang, Yanpeng Mao, Zhanlong Song, Murodbek Safaraliev, Xingxing Cheng and Ziliang Wang

Catalysts 2026, 16(6), 560; https://doi.org/10.3390/catal16060560 - 17 Jun 2026

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Abstract

The utilization of biomass resources is of significant importance. However, the complexity of biomass thermochemical conversion processes and the performance limitations of conventional catalysts restrict the stable selection of reaction pathways and ultimately affect catalytic yields. With the rapid development of synthesis techniques [...] Read more.

The utilization of biomass resources is of significant importance. However, the complexity of biomass thermochemical conversion processes and the performance limitations of conventional catalysts restrict the stable selection of reaction pathways and ultimately affect catalytic yields. With the rapid development of synthesis techniques and machine learning, nanoscale high-entropy alloys (HEAs) with targeted properties can now be accurately predicted and synthesized. The diverse compositions and structures of HEAs enable versatile catalytic selectivity, while their unique four core effects enhance catalytic activity and stability. This review primarily elaborates on the specific applications of HEAs in biomass thermochemical conversion. It covers the fundamental characteristics of HEAs, preparation methods, and machine learning-driven design strategies. Summarized the directional conversion and value-added research of high-entropy alloys in biomass thermal conversion intermediates. This demonstrates the excellent application adaptability of high-entropy alloys in complex reaction systems. Finally, prospects for the rational design of high-entropy alloy catalysts and their application in biomass refining technologies are outlined. Full article

(This article belongs to the Special Issue Catalysis for Solid Waste Upcycling: Challenges and Opportunities)

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14 pages, 12318 KB

Open AccessArticle

Solid-Phase Synthesis of Metal-Free Melamine-Based Catalysts for CO₂ Utilization

by Shuai Li, Sander Dekyvere, Zhonghan Cheng, Somboon Chaemchuen, Min Jiang, Cheng Chen and Francis Verpoort

Catalysts 2026, 16(6), 559; https://doi.org/10.3390/catal16060559 - 17 Jun 2026

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Abstract

Recent advancements in heterogeneous catalysis have increased the interest in the synthesis of metal-free polymer-based catalysts. This work presents a novel approach for the solvent- and additive-free synthesis of a nitrogen-rich catalyst. Our unique procedure yields a non-porous organic polymer (NPOP) with a [...] Read more.

Recent advancements in heterogeneous catalysis have increased the interest in the synthesis of metal-free polymer-based catalysts. This work presents a novel approach for the solvent- and additive-free synthesis of a nitrogen-rich catalyst. Our unique procedure yields a non-porous organic polymer (NPOP) with a wide range of functional groups on the surface, attributed to the incomplete polymerization inherent to our solvent-free method. Detailed analysis revealed significant differences between NPOP and its Covalent Organic Framework counterpart. Remarkably, the absence of a high surface area did not hinder the efficiency of NPOP as a catalyst for the CO₂ cycloaddition. The performance of NPOP exceeded that of its COF counterpart, with a conversion rate of 99% for NPOP and 35% for the COF. An observation attributed to the abundance of nitrogen functional groups on the surface of NPOP. A combination of characterizations and density functional theory (DFT) calculations was employed to thoroughly understand the working mechanism of NPOP. The imines and secondary amines on the surface function as the active sites for the ring-opening of epichlorohydrin. This study supports existing theories that N atoms can serve as nucleophiles by donating their free electron pairs. Furthermore, the distinctive synthesis procedure reported here can serve as inspiration for further design of polymer-based catalysts. Full article

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

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21 pages, 2112 KB

Open AccessReview

Research and Perspectives on Surface Functional Group Characterization of Activated Carbon Catalysts

by Xiaochen Liu, Minyang Liu, Chaofeng Ma, Houlin Yu, Wanjin Yu and Wucan Liu

Catalysts 2026, 16(6), 558; https://doi.org/10.3390/catal16060558 - 17 Jun 2026

Viewed by 418

Abstract

Activated carbon is a commonly used catalyst and catalyst support. Its abundant surface groups play a key role in catalytic activity and selectivity, and therefore an in-depth investigation of the surface groups of activated carbon is of great significance. The surface groups of [...] Read more.

Activated carbon is a commonly used catalyst and catalyst support. Its abundant surface groups play a key role in catalytic activity and selectivity, and therefore an in-depth investigation of the surface groups of activated carbon is of great significance. The surface groups of activated carbon are diverse and structurally complex, and the corresponding characterization methods are also varied, with each technique having its own advantages and limitations. This review systematically summarizes the sources, characteristics, and effects on catalytic processes of oxygen-containing, nitrogen-containing, phosphorus-containing, and other heteroatom-containing groups on activated carbon surfaces. Emphasis is placed on the application of Boehm titration, PZC/IEP, FT-IR, XPS, TPD-MS, Raman, XRD, solid-state NMR, SEM/EDS, and EPR/ESR in the study of surface groups on activated carbon. Because the formation and alteration of surface groups on activated carbon not only change the surface chemical properties of activated carbon but also affect its structure, charge, and related properties, a single characterization method cannot accurately and comprehensively reveal its characteristics. Therefore, in practical studies, multiple characterization methods should be combined for cross-validation from the perspectives of functional group type, chemical state, thermal stability, structural changes, and catalytic behavior, so as to establish reliable correlations among “group type–structural environment–catalytic performance” and provide a basis for the rational design and optimization of activated carbon catalysts. Full article

(This article belongs to the Special Issue Advanced Carbon-Based Catalytic Materials for Energy Storage and Conversion)

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20 pages, 6462 KB

Open AccessArticle

A Dual-Bed Catalyst System for Maximizing H₂ Production Through Catalytic Partial Oxidation of CH₄

by Pannipa Nachai, Pornlada Daorattanachai, Pattarapon Rungsri and Navadol Laosiripojana

Catalysts 2026, 16(6), 557; https://doi.org/10.3390/catal16060557 - 16 Jun 2026

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Abstract

The efficient conversion of methane into hydrogen-rich syngas is essential for sustainable energy; however, integrating methane partial oxidation (POM) with the water–gas shift (WGS) reaction remains a significant challenge due to thermal and kinetic mismatches. This research presents a spatially decoupled dual-bed reactor [...] Read more.

The efficient conversion of methane into hydrogen-rich syngas is essential for sustainable energy; however, integrating methane partial oxidation (POM) with the water–gas shift (WGS) reaction remains a significant challenge due to thermal and kinetic mismatches. This research presents a spatially decoupled dual-bed reactor configuration, utilizing Ni/GDC and Cu/GDC catalysts, to achieve synergistic hydrogen production. Unlike conventional physically mixed systems, which suffer from thermal hotspots and the unintended promotion of the endothermic Reverse Water–Gas Shift (RWGS) reaction, the dual-bed architecture effectively segregates the reaction zones. Advanced characterization, including O₂-TPO and Raman spectroscopy, reveals that the GDC support acts as a critical oxygen buffer via the Mars-van Krevelen mechanism, modulating the dynamic redox state of the active metal sites to prevent deep oxidation and carbonaceous deactivation. Furthermore, macroscopic performance and carbon–oxygen mass balance analyses confirm that this rational architectural design facilitates a seamless integration of POM and WGS pathways, resulting in significantly maximized H₂ yield. From a broader engineering perspective, this dual-bed strategy offers a practical, low-complexity alternative to intensive integrated technologies such as sorption-enhanced reforming (SER) or chemical looping, providing a robust and scalable framework for durable, high-efficiency hydrogen production. Full article

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11 pages, 2611 KB

Open AccessArticle

Chiral Phosphoric Acid-Catalyzed Hydrolysis of 4H-Oxazines for Diverse Syntheses

by Peng-Ying Jiang, Ziyin Guo, San Wu, Shao-Hua Xiang, Jun (Joelle) Wang and Bin Tan

Catalysts 2026, 16(6), 556; https://doi.org/10.3390/catal16060556 - 16 Jun 2026

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Abstract

The use of water as a nucleophile in catalytic asymmetric reactions remains a significant challenge, primarily due to its intrinsically low nucleophilicity and small size, which make precise control over both reactivity and stereoselectivity particularly difficult. To address this issue, we developed a [...] Read more.

The use of water as a nucleophile in catalytic asymmetric reactions remains a significant challenge, primarily due to its intrinsically low nucleophilicity and small size, which make precise control over both reactivity and stereoselectivity particularly difficult. To address this issue, we developed a CPA-catalyzed asymmetric hydrolysis system, successfully achieving the efficient and highly stereoselective transformation of 4H-oxazines with water. Under this catalytic system, the initial formation of chiral α-bromo ketones is followed by their in situ conversion through reduction and intramolecular S_N2 reactions, directly affording valuable chiral bromo alcohols and chiral oxazolone derivatives in high yields with excellent enantioselectivity. Full article

(This article belongs to the Special Issue Recent Developments in Asymmetric Organocatalysis)

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3 pages, 137 KB

Open AccessEditorial

Green Chemistry and Catalysis

by Nesreen S. Ahmed, Tamer S. Saleh and Mohamed Mokhtar M. Mostafa

Catalysts 2026, 16(6), 555; https://doi.org/10.3390/catal16060555 - 16 Jun 2026

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Abstract

The principles of green chemistry—waste reduction, atom economy, safer synthesis, energy efficiency, and the use of renewable feedstocks—are intrinsically linked to catalysis [...] Full article

(This article belongs to the Special Issue Green Chemistry and Catalysis)

18 pages, 2871 KB

Open AccessArticle

Halogen-Substituted Co(II) Phthalocyanines as Efficient Catalysts for Benzyl Alcohol Oxidation: Steric Effects on Activity and Selectivity

by Cagla Akkol, Gizem Genc, Birhan Tutal, İsmail Uzunel and Ece Tugba Saka

Catalysts 2026, 16(6), 554; https://doi.org/10.3390/catal16060554 - 16 Jun 2026

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Abstract

Steric effects refer to the effect of the size and spatial arrangement of atoms or groups on the reactions, interactions, and catalytic activities of molecules. The incorporation of Cl (chlorine) and Br (bromine) atoms as substituents into phthalocyanine (Pc) structures can have important [...] Read more.

Steric effects refer to the effect of the size and spatial arrangement of atoms or groups on the reactions, interactions, and catalytic activities of molecules. The incorporation of Cl (chlorine) and Br (bromine) atoms as substituents into phthalocyanine (Pc) structures can have important catalytic effects. These effects arise mainly from their electronic and steric properties, which influence the behavior of the central metal ion and the overall catalyst performance. In this work, Co(II)PcQBr₂ was synthesized and characterized by spectral techniques. The catalytical activity of Co(II)PcQBr₂ was then evaluated for the oxidation of benzyl alcohol. The effects of the substrate/catalyst ratio, oxidant/catalyst ratio, oxidant type and temperature on the oxidation reaction of benzyl alcohol were investigated. Both catalysts exhibited high TON, TOF and total conversion yields in the presence of H₂O₂ as the oxidant at 50 °C. (substrate/oxidant/catalyst:1000/500/1). When the total product conversions were calculated for both catalysts, Co(II)PcQBr₂ was found to have a lower product conversion (88.7%, with a TON of 914 and a TOF of 457 ) than Co(II)PcQCl₂. Moreover, Co(II)PcQCl₂ was determined to have higher selectivity of benzyl benzoate (94.0%, with a TON of 940 and a TOF of 470 ). The larger size of the Br atom compared to that of the Cl atom was observed to reduce catalytic activity. Considering the size of the Cl atom, it was concluded that steric effects favor the formation of benzyl benzoate by inhibiting possible side reactions, thus increasing the catalytic activity. Full article

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16 pages, 1081 KB

Open AccessArticle

Integrated Electro/Fe³⁺/Peroxydisulfate Treatment for Sulfamethazine Degradation and Biodegradability Enhancement

by Amina Ledjeri, Katia Madi, Idris Yahiaoui, Amine Aymen Assadi, Mohammod Hafizur Rahman, Abdeltif Amrane and Farida Aissani-Benissad

Catalysts 2026, 16(6), 553; https://doi.org/10.3390/catal16060553 - 15 Jun 2026

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Abstract

This study investigates the degradation and mineralization of sulfamethazine (SMT) by an electrochemically assisted Fe³⁺/persulfate (electro/Fe³⁺/PDS) process. Experiments were conducted in a single-compartment electrochemical cell equipped with a carbon felt anode and a stainless steel cathode under constant current [...] Read more.

This study investigates the degradation and mineralization of sulfamethazine (SMT) by an electrochemically assisted Fe³⁺/persulfate (electro/Fe³⁺/PDS) process. Experiments were conducted in a single-compartment electrochemical cell equipped with a carbon felt anode and a stainless steel cathode under constant current conditions. Compared with PDS alone and Fe³⁺/PDS, the combined electro/Fe³⁺/PDS system exhibited a strong synergistic effect, achieving up to 89.4% SMT removal within 90 min at a current intensity of 1.6 A. The enhanced performance was attributed to electrochemical Fe²⁺ regeneration enabling continuous activation of persulfate and generation of sulfate radicals (SO₄^•−). Operational parameters significantly influenced process efficiency. Increasing current intensity accelerated SMT degradation but reduced mineralization efficiency due to parasitic reactions. Under optimized conditions (I = 3 A and [Fe³⁺] = 1 mM), SMT degradation reached 96.83% after 60 min, while the mineralization yield attained 72.05%. Excess iron promoted radical scavenging. Similarly, a PDS concentration of 5 mM was sufficient, with higher dosages leading to self-scavenging effects. Kinetic analysis followed a pseudo first order model, with apparent rate constants decreasing at higher SMT concentrations due to radical competition. Biodegradability assays revealed a substantial increase in the BOD₅/COD ratio from initially low values to 0.34 after 300 min of pretreatment, indicating improved suitability for biological post-treatment. Overall, the electro/Fe³⁺/PDS process represents an efficient pre-oxidation strategy for the removal of refractory antibiotics from aqueous media. Full article

(This article belongs to the Special Issue Biocatalysts in Biodegradation and Bioremediation)

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15 pages, 1119 KB

Open AccessFeature PaperArticle

Chemo-Enzymatic Synthesis of the Key Chiral Intermediate of d-Biotin

by Chang-Li Xu, Xiao-Mei Wu, Bao-Di Ma and Yi Xu

Catalysts 2026, 16(6), 552; https://doi.org/10.3390/catal16060552 - 15 Jun 2026

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Abstract

The (3aS, 6aR)-lactone serves as the key chiral intermediate for the synthesis of d-biotin. A promising approach involves the asymmetric hydrolysis of meso-dimethyl ester catalyzed by an esterase to yield the (4S, 5R)-monomethyl ester, which [...] Read more.

The (3aS, 6aR)-lactone serves as the key chiral intermediate for the synthesis of d-biotin. A promising approach involves the asymmetric hydrolysis of meso-dimethyl ester catalyzed by an esterase to yield the (4S, 5R)-monomethyl ester, which is subsequently reduced and cyclized to afford (3aS, 6aR)-lactone. This study first optimized the fermentation medium and culture conditions for the recombinant E. coli pET21a-EstSIT01 harboring the Microbacterium esterase gene, which exhibits high selectivity for the asymmetric synthesis of (4S, 5R)-monomethyl ester. Under optimal conditions (fermentation medium: glycerol 25 g/L, yeast extract 15 g/L, NaCl 10 g/L, MgSO₄•7H₂O 5 g/L; induction was initiated 2 h post-inoculation at 30 °C and pH 7.2), the enzyme activity increased 5.1-fold compared to the initial level, reaching 1072.7 U/L. Secondly, the reaction conditions for the whole-cell synthesis of (4S, 5R)-monomethyl ester catalyzed by EstSIT01 were optimized. The results indicated that organic solvents adversely affected enzyme stability, while high buffer salt concentration negatively impacted enzyme activity at elevated substrate concentrations. The optimal reaction strategy involved maintaining the pH of the aqueous reaction system at 7.5 by the controlled addition of aqueous ammonia to neutralize the (4S, 5R)-monomethyl ester produced during the reaction. Using 17.5 g/L cells and 200 mM substrate meso-dimethyl ester in deionized water, with the reaction pH mentioned at 7.5, complete conversion (100%) was achieved within 4 h at 30 °C. The space–time yield reached 441.6 g/L/d, exceeding the typical requirement for industrial biotransformation (>100 g/L/d), with 99.1% enantiomeric excess (ee) of (4S, 5R)-monomethyl ester. Finally, (4S, 5R)-monomethyl ester was reduced using sodium borohydride to synthesize (3aS, 6aR)-lactone with an ee value of 98.7%. The overall yield from meso-dimethyl ester to (3aS, 6aR)-lactone was 86.2%. These results demonstrate that this integrated chemo-enzymatic approach constitutes a greener method with promising potential for industrial application. Full article

(This article belongs to the Special Issue 15th Anniversary of Catalysts: The Future of Enzyme Biocatalysis)

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16 pages, 3706 KB

Open AccessArticle

Controllable Synthesis of Silver–Copper Bimetallic Nanoparticle-Decorated Reduced Graphene Oxide Composites with Enhanced Electrocatalytic Performance

by Youzhi Yao, Ping Cheng, Xiaohan Wang, Qinghua Deng, Tiancheng Yao, Jiaxin Jiang and Wenjie Wu

Catalysts 2026, 16(6), 551; https://doi.org/10.3390/catal16060551 - 15 Jun 2026

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Abstract

Monometallic nanoparticles tend to aggregate and exhibit limited catalytic performance, rendering them inadequate for high-efficiency electrocatalytic applications. In this study, a green and mild liquid-phase reduction method was employed, using sodium borohydride to simultaneously reduce graphene oxide (GO) and metal precursors. This approach [...] Read more.

Monometallic nanoparticles tend to aggregate and exhibit limited catalytic performance, rendering them inadequate for high-efficiency electrocatalytic applications. In this study, a green and mild liquid-phase reduction method was employed, using sodium borohydride to simultaneously reduce graphene oxide (GO) and metal precursors. This approach enabled the uniform and highly dispersed loading of silver–copper bimetallic alloy nanoparticles (Ag_1−xCu_x NPs) onto the surface of reduced graphene oxide (RGO). By tuning the Ag/Cu molar ratio, the size, composition, and morphology of the nanoparticles were precisely controlled. Characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed that GO was efficiently reduced to RGO, and the bimetallic nanoparticles were uniformly distributed on the RGO surface in an alloy state with small particle size and no obvious agglomeration. A strong interfacial interaction between the metal nanoparticles and the support was also observed. Electrochemical tests demonstrated that the composite exhibits excellent electrocatalytic activity toward the reduction of H₂O₂. Notably, the reduction peak current at the Ag_0.5Cu_0.5NPs/RGO modified electrode was 1.8 and 2.3 times higher than those at the monometallic Ag/RGO and Cu/RGO electrodes, respectively. These results provide a reliable theoretical basis and a viable research route for the controllable synthesis of low-cost, high-performance electrocatalytic nanocomposites and their application in electrochemical H₂O₂ sensing. Full article

(This article belongs to the Section Catalytic Materials)

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27 pages, 3242 KB

Open AccessArticle

Deciphering the Antioxidant Activity and Enzyme Inhibition of Luteolin and Its Glycosides: An Integrated In Vitro and In Silico Approach

by Adem Ertürk and Ilhami Gulcin

Catalysts 2026, 16(6), 550; https://doi.org/10.3390/catal16060550 - 14 Jun 2026

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Abstract

Luteolin and its derivative glycosides (cynaroside, orientin and isoorientin) are compounds with a flavonoid structure of plant origin. There are different studies in the literature on the antioxidant capacities of the structures and their inhibition effects on some enzymes. In this study, the [...] Read more.

Luteolin and its derivative glycosides (cynaroside, orientin and isoorientin) are compounds with a flavonoid structure of plant origin. There are different studies in the literature on the antioxidant capacities of the structures and their inhibition effects on some enzymes. In this study, the antioxidant capacities of each structure were determined comparatively, and their inhibitory effects against enzymes associated with different diseases such as acetylcholinesterase, butyrylcholinesterase, α-glycosidase and α-amylase were evaluated by comparative investigation in vitro and in silico. Antioxidant capacities were determined for each structure by iron ions (Fe³⁺), cupric ions (Cu²⁺), Fe³⁺−Triphenyltetrazolium chloride (TPTZ) reduction methods and 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), N,N-dimethyl-p-phenylenediamine (DMPD) radical scavenging methods. According to the results obtained, it was determined that the antioxidant capacities of the structures were close to or better than butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trolox, α tocopherol and ascorbic acid, which are used as standard antioxidants. The results of the study, which was conducted to determine the inhibition effects of the structures on the determined enzymes, were found to coincide experimentally and theoretically. According to the inhibition results, the best inhibitors were found as orientin (IC₅₀: 27.729 nM) for the human carbonic anhydrase I (hCA I), cynaroside (IC₅₀: 18.24 nM) for the human carbonic anhydrase I (hCA II), isoorientin (IC₅₀: 1.93 nM) for the acetylcholinesterase (AChE), and cynaroside (IC₅₀: 6.41 and 7.15 nM) for the butyrylcholinesterase (BChE) and α-glycosidase enzymes. Additionally, absorption, distribution, metabolism, and excretion (ADME) profiles and toxicity assessments of the structures were determined in a virtual environment. Full article

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

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18 pages, 4182 KB

Open AccessArticle

Chicken Bile-Mediated Silver Nanoparticles: Performance in Antibacterial Activity and Photodegradation of Disperse Orange 1

by Muhammad Bilal, Javed Ali, Zahida Bibi, Tallat Munir, Esraa M. Bakhsh, Kalsoom Akhtar and Sher Bahadar Khan

Catalysts 2026, 16(6), 549; https://doi.org/10.3390/catal16060549 - 13 Jun 2026

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Abstract

Chicken bile-mediated silver nanoparticles (Ag-NPs) were synthesized and evaluated via UV–Vis, SEM, FTIR, and XRD. The synthesis of Ag-NPs was validated by observing a color change that was visible to the naked eye and via UV–Vis spectroscopy. A peak at 435 nm in [...] Read more.

Chicken bile-mediated silver nanoparticles (Ag-NPs) were synthesized and evaluated via UV–Vis, SEM, FTIR, and XRD. The synthesis of Ag-NPs was validated by observing a color change that was visible to the naked eye and via UV–Vis spectroscopy. A peak at 435 nm in the UV–Vis spectrum suggest the formation of Ag-NPs. The FTIR spectrum indicated that Ag⁺ reduction into Ag-NPs may occur due to proteins that are present in chicken bile. The XRD results showed that the nanoparticles were crystalline in nature, with a crystallite size of 25 nm. The SEM images showed that spherical-shaped nanoparticles with an average size of 20–60 nm were formed. The effects of different parameters, such as extract concentration, pH, and temperature, on the shape and reaction rate of Ag-NPs were examined. The results showed that the formation of Ag-NPs increased substantially in basic medium and they were found to be more stable at 60 °C. The prepared Ag-NPs were evaluated for their antibacterial activity and photocatalytic efficiency in degrading Disperse Orange 1 (DOI) dye. The antibacterial assessment of the synthesized Ag-NPs showed significant antibacterial activity. Based on the photodegradation study, it was found that the synthesized Ag-NPs showed high activity and almost complete (97%) degradation of DOI within the first 100 min. Thus, the overall results reveal that the prepared Ag-NPs offer a better approach for remediating the aforementioned contaminants. Full article

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

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22 pages, 2085 KB

Open AccessReview

Modification Strategies and Photocatalytic Applications of Bismuth Tungstate Photocatalysts

by Xiaoying Cui, Yixin Cao, Yiming Dong, Rui Song and Zhaoping Song

Catalysts 2026, 16(6), 548; https://doi.org/10.3390/catal16060548 - 13 Jun 2026

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Abstract

Bismuth tungstate (Bi₂WO₆) is a typical bismuth-based visible-light-responsive semiconductor photocatalyst that has attracted significant attention in the fields of environment remediation and energy conversion. In this paper, to address the issues of high photogenerated carrier recombination rate and limited [...] Read more.

Bismuth tungstate (Bi₂WO₆) is a typical bismuth-based visible-light-responsive semiconductor photocatalyst that has attracted significant attention in the fields of environment remediation and energy conversion. In this paper, to address the issues of high photogenerated carrier recombination rate and limited visible-light-response range of Bi₂WO₆, various modification strategies are highlighted, including morphology control, element doping, heterojunction construction, carbon material compositing, and coupling with functional materials such as metal–organic frameworks (MOFs), covalent organic frameworks (COFs), or conductive polymers. Furthermore, the structure–activity relationships are discussed. On this basis, the latest application progress of Bi₂WO₆-based photocatalysts in fields such as pollutant degradation, antibacterial activity, and energy conversion and storage is summarized. Finally, prospects are put forward regarding the existing shortcomings and future development directions in the application of Bi₂WO₆-based photocatalysts, aiming to provide a systematic theoretical reference for the design and application of high-performance Bi₂WO₆-based photocatalysts. Full article

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68 pages, 17802 KB

Open AccessReview

Structured Layered Double Hydroxide-Based Catalysts for Process Intensification: Transport, Stability, and Scale-Up in Monoliths, Foams, Films, and Washcoats

by Özgür Yılmaz and Ahmet Akif Kızılkurtlu

Catalysts 2026, 16(6), 547; https://doi.org/10.3390/catal16060547 - 12 Jun 2026

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Abstract

There is increasing interest in structured layered double hydroxide (LDH)-based catalysts because they combine tunable acid–base/redox chemistry with reactor architectures that can reduce diffusion lengths, improve heat management, and lower pressure-drop penalties. This review evaluates LDH, LDH-derived oxide (LDO/MMO), reduced metal/LDO, reconstructed hydroxide-rich, [...] Read more.

There is increasing interest in structured layered double hydroxide (LDH)-based catalysts because they combine tunable acid–base/redox chemistry with reactor architectures that can reduce diffusion lengths, improve heat management, and lower pressure-drop penalties. This review evaluates LDH, LDH-derived oxide (LDO/MMO), reduced metal/LDO, reconstructed hydroxide-rich, and mixed dynamic states integrated into honeycomb monoliths, open-cell foams, meshes/felts, thin films, washcoats, coated plates, microchannels, capillaries, and additively manufactured lattices. To move beyond descriptive comparison, the literature is assessed using unified evaluation dimensions: operative active state, support architecture, coating/integration route, active-phase loading, coating thickness and uniformity, reactor-volume-normalized productivity or STY, ΔP/L, axial/radial thermal gradients, time-on-stream, coating loss, regeneration recovery, and pilot-readiness. Representative benchmarks illustrate both the promise and reporting gaps of the field: NiFe-LDH-derived monoliths for CO₂ methanation have reached ~70% CO₂ conversion at 300 °C with >90% CH₄ selectivity and only 0.7% post-test mass loss; NiFe-LDH/iron-foam monoliths retained 85% ozone conversion after 168 h; high-entropy LDH-derived oxides showed T50/T90 values of 246/254 °C for toluene oxidation; and Au/LDH capillary films achieved 31.9% glycerol carbonate yield and 3.78 g h⁻¹ g⁻¹ productivity. The strongest current cases are pollution abatement and CO₂ methanation, whereas biomass upgrading, fine-chemical flow, high-entropy coatings, and photo/electrocatalytic films require deeper module-level validation. Overall, structured LDH catalysts should be treated as coupled chemistry–coating–reactor systems whose performance must be judged simultaneously by activity, accessible catalyst inventory, transport efficiency, pressure drop, thermal profile, durability, regeneration, and manufacturability. Full article

(This article belongs to the Collection Layered Double Hydroxides and Related Materials for Advanced Heterogeneous Catalytic Processes)

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18 pages, 1554 KB

Open AccessArticle

Whole-Cell Biocatalytic Degradation of Heavy Oil Under Low Temperature by a Pseudomonas Strain Isolated from Oil-Contaminated Sites

by Shakir Ali, Isha and Young-Cheol Chang

Catalysts 2026, 16(6), 546; https://doi.org/10.3390/catal16060546 - 12 Jun 2026

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Abstract

The removal of heavy oil under low-temperature conditions is a significant global challenge. This study aimed to assess the long-term whole-cell biocatalytic degradation of heavy oil in water and soil by bacteria isolated from contaminated soil in Muroran, Japan, under cold conditions. Enrichment [...] Read more.

The removal of heavy oil under low-temperature conditions is a significant global challenge. This study aimed to assess the long-term whole-cell biocatalytic degradation of heavy oil in water and soil by bacteria isolated from contaminated soil in Muroran, Japan, under cold conditions. Enrichment cultures using heavy oil as the sole carbon source yielded 15 potent heavy oil-degrading isolates. However, only the C1 strain retained its activity under low-temperature conditions and was identified as Pseudomonas aeruginosa C1 using 16S rDNA sequencing. Gas chromatography analysis revealed that at 30 °C (water medium), strain C1 degraded 57% of heavy oil within 7 days. At 15 °C, the degradation efficiency of C1 declined due to a temperature-dependent metabolic lag phase (1 day); however, at 15 °C, 70% degradation was observed in seven days. In long-term experiments at 5 °C and 10 °C, 35% and 40% degradation were recorded for C1 after 98 days. In artificially contaminated soil at 5 °C, C1 achieved 60% biodegradation. These results demonstrate cold-adapted whole-cell activity against heavy oil and motivate the design of controlled, contained ex situ reactors (e.g., enzyme-based or cell-free systems) for safe remediation in cold climates. Full article

(This article belongs to the Special Issue Biocatalysts in Biodegradation and Bioremediation)

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15 pages, 2963 KB

Open AccessArticle

The Excellent Anti-K Ability of CeSbTi Oxide Catalysts for Selective Catalytic Reduction of NO with NH₃

by Jiahui Zhang, Minghan Li, Xiang Liang, Yanping Ma, Junge Li, Shun Li and Hong Jiang

Catalysts 2026, 16(6), 545; https://doi.org/10.3390/catal16060545 - 12 Jun 2026

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Abstract

A novel K-resistant CeSbTi mixed oxide catalyst was prepared by co-precipitation method for ammonia selective catalytic reduction (NH₃-SCR) of NO_x. The experimental results show that the introduction of Sb₂O₅ can significantly improve the catalytic activity of [...] Read more.

A novel K-resistant CeSbTi mixed oxide catalyst was prepared by co-precipitation method for ammonia selective catalytic reduction (NH₃-SCR) of NO_x. The experimental results show that the introduction of Sb₂O₅ can significantly improve the catalytic activity of the CeTi catalyst. The modulated CeSbTi catalyst has good resistance to K, and the NO_x conversion rate was as high as 95% after K poisoning. Its superior catalytic activity could be ascribed to the large specific surface area with increased acid sites and more oxygen defects and Ce³⁺ species after the introduction of Sb₂O₅, which prompt NH₃ adsorption and activation. In addition, NH₃-SCR reaction over CeSbTi and K/CeSbTi catalysts follows the E-R mechanism. The introduced Sb-O bond as the base capture site preferentially binds to potassium and releases part of the active Ce sites, thus retaining more acid sites and oxygen defects to a certain extent. Full article

(This article belongs to the Special Issue Advanced Catalytic Technologies for NO_x Abatement and Environmental Sustainability)

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21 pages, 32972 KB

Open AccessArticle

Cobalt–Copper Bimetallic Mesoporous Carbon Catalyst Activated by Peroxymonosulfate for Efficient Degradation of Tetracycline

by Xueting Shi, Wei Yan, Jun Lu, Ranran Zhou, Qijie Jin, Liguo Chen, Mutao Xu, Changcheng Zhou and Haitao Xu

Catalysts 2026, 16(6), 544; https://doi.org/10.3390/catal16060544 - 12 Jun 2026

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Abstract

To efficiently degrade tetracycline (TC) antibiotic pollution, cobalt-based (Co-OMCs/F) and cobalt–copper bimetallic ((Co+Cu)-OMCs/F) monolithic mesoporous carbon catalysts were synthesized using resorcinol–formaldehyde resin as a carbon precursor, with hexamethylenetetramine (HMT) and formaldehyde (CH₂O) as crosslinking agents, followed by high-temperature carbonization under N [...] Read more.

To efficiently degrade tetracycline (TC) antibiotic pollution, cobalt-based (Co-OMCs/F) and cobalt–copper bimetallic ((Co+Cu)-OMCs/F) monolithic mesoporous carbon catalysts were synthesized using resorcinol–formaldehyde resin as a carbon precursor, with hexamethylenetetramine (HMT) and formaldehyde (CH₂O) as crosslinking agents, followed by high-temperature carbonization under N₂. The materials were characterized by XRD, SEM-EDX, HRTEM, and EPR. Key factors-metal loading, PMS concentration, initial pH, and flow rate-were investigated for their effects on TC degradation. Degradation mechanisms and stability were assessed via radical quenching and continuous-flow cycling tests. Results show optimal performance at a cobalt loading of 0.6 g. Compared to CH₂O, HMT favors a three-dimensional interconnected mesoporous carbon framework with uniform metal distribution and high crystallinity. Under conditions of 25 mg/L TC, 0.33 mmol/L PMS, pH 7, and 2 mL/min flow rate, the (Co+Cu)-OMCs/F (HMT) catalyst achieved ~93% TC degradation over 9 h of continuous operation, and 95% after three reuse cycles, significantly outperforming the single-metal Cu-OMCs/F catalyst. Radical quenching and EPR identified superoxide radicals (·O₂⁻) as the dominant active species (~78% contribution), with sulfate radicals (SO₄^·−), hydroxyl radicals (·OH), and singlet oxygen (¹O₂) playing synergistic roles. The synergistic Co-Cu bimetallic effect, combined with the confinement effect of the mesoporous carbon support and HMT-induced uniform nucleation, endows the catalyst with high activity and long-term stability. This work provides a theoretical basis for designing efficient, reusable, monolithic mesoporous carbon-based PMS activation catalysts for advanced antibiotic wastewater treatment. Full article

(This article belongs to the Special Issue Green Catalytic Materials for Environmental Application)

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