Catalysts

17 pages, 2458 KB

Open AccessArticle

Selective Electrochemical Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran with NiAl Layered Double Hydroxide Nanosheet Catalysts

by Siyi Zhong, Jianxiang Shi, Yongming Luo, Jian Fang and Shuquan Huang

Catalysts 2026, 16(5), 487; https://doi.org/10.3390/catal16050487 - 21 May 2026

Viewed by 664

Abstract

The selective oxidative transformation of 5-hydroxymethylfurfural (HMF) is a key route toward producing a wide variety of chemicals in the biorefinery industry. Herein, we report a NiAl layered double hydroxide (NiAl-LDH) catalyst as a highly effective electrocatalytic oxidation catalyst for the transformation of [...] Read more.

The selective oxidative transformation of 5-hydroxymethylfurfural (HMF) is a key route toward producing a wide variety of chemicals in the biorefinery industry. Herein, we report a NiAl layered double hydroxide (NiAl-LDH) catalyst as a highly effective electrocatalytic oxidation catalyst for the transformation of HMF into 2,5-diformylfuran (DFF), a valuable furan-based chemical, with about 75.53% DFF selectivity under neutral conditions. It demonstrated good stability without deactivation after 9 cycles of repeated electrolysis. The NiAl-LDH electrocatalyst was deposited on a nickel foam support via a hydrothermal method, and its structural properties and surface morphology were extensively investigated. Systematic studies of reaction temperature, current intensity, and electrolyte concentration revealed that the neutral electrolyte plays a critical role in achieving high DFF selectivity by suppressing aldehyde over-oxidation. Mechanistic investigations with electrochemically active surface area (ECSA), electrochemical impedance spectroscopy (EIS), Tafel slope and density functional theory (DFT) calculations revealed that the reversible transformation between Ni(OH)₂ and active NiOOH species in the NiAl-LDH electrocatalyst was the main reason for the oxidation of HMF, while the incorporation of Al provided structural support to the electrode, enabling the catalyst to exhibit excellent stability during electrolysis. Overall, this work demonstrates an active, earth-abundant metal electrocatalyst for the valorization of biomass-derived 5-HMF to DFF. Full article

(This article belongs to the Special Issue Photo/Electrocatalysis: Advancing Sustainable Energy and Environmental Health)

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19 pages, 2357 KB

Open AccessArticle

Application of Simultaneous Chemical and Electrochemical Oxidation Treatment (O₃–EO) in River Water and Its Pollutant and Phytotoxicity Evaluation

by Ariana de la Cruz-Hernández, Gabriela Roa-Morales, Carlos Eduardo Barrera-Díaz, Lilia Tapia-López, Cinthya Pamela Del Río Galván and Manuel Eduardo Palomar-Pardavé

Catalysts 2026, 16(5), 486; https://doi.org/10.3390/catal16050486 - 21 May 2026

Cited by 1 | Viewed by 559

Abstract

Continuous discharges from diverse industrial activities have severely degraded the water quality of the Lerma River, turning it into a major environmental, social, and public health concern. Conventional wastewater treatment processes are often insufficient for eliminating persistent and refractory organic pollutants; therefore, the [...] Read more.

Continuous discharges from diverse industrial activities have severely degraded the water quality of the Lerma River, turning it into a major environmental, social, and public health concern. Conventional wastewater treatment processes are often insufficient for eliminating persistent and refractory organic pollutants; therefore, the implementation of advanced oxidation processes (AOPs) is increasingly required to restore water quality. In this context, the present study systematically evaluated the individual and combined effects of ozonation and electrochemical oxidation using boron-doped diamond (BDD) electrodes for the treatment of contaminated river water. Ozonation alone achieved an 89% reduction in turbidity and a 19% decrease in total organic carbon (TOC), while electrochemical oxidation reduced turbidity by 82% and TOC by 57%. Remarkably, the simultaneous application of both treatments resulted in a 98% reduction in turbidity and an 80% decrease in TOC, clearly demonstrating a strong synergistic effect. Regarding true color at 436 nm, associated with yellow chromophore compounds, removal efficiencies of 98.9%, 94.7%, and 67.3% were obtained for the combined process, electrochemical oxidation, and ozonation, respectively. Phytotoxicity tests with Lactuca sativa seeds showed no statistically significant difference in toxicity in water treated with the O₃–EO System compared to raw water. These results highlight, for the first time under real river water conditions, the superior performance of the integrated O₃–EO system as an effective strategy for the intensified degradation and partial mineralization of persistent organic contaminants, thereby underscoring its strong potential for advanced remediation of heavily polluted surface waters. Full article

(This article belongs to the Special Issue Photocatalysis and Electrocatalysis for Water Remediation)

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25 pages, 21862 KB

Open AccessArticle

Catalytic Pyrolysis of Açaí (Euterpe oleracea Mart.) Seeds: Circular Economy for Agro-Industrial Waste-to-Energy in the Amazon

by Douglas Alberto Rocha de Castro, Haroldo Jorge da Silva Ribeiro, Lauro Henrique Hamoy Guerreiro, Fernanda Paula da Costa Assunção, Lucas Pinto Bernar, Nilton Pereira da Silva, Daniela Muniz D’Antona Guimarães, Marta Chagas Monteiro, Luiz Eduardo Pizarro Borges, Kerstin Kuchta, Nélio Teixeira Machado and Sergio Duvoisin, Jr.

Catalysts 2026, 16(5), 485; https://doi.org/10.3390/catal16050485 - 21 May 2026

Viewed by 1576

Abstract

This study aims to systematically investigate the combined effect of chemical activation of açaí seeds (Euterpe oleracea Mart.), with an aqueous sodium hydroxide (NaOH) solution at 2 mol·L⁻¹, and process temperature by pyrolysis of alkaline activated açaí seeds on the [...] Read more.

This study aims to systematically investigate the combined effect of chemical activation of açaí seeds (Euterpe oleracea Mart.), with an aqueous sodium hydroxide (NaOH) solution at 2 mol·L⁻¹, and process temperature by pyrolysis of alkaline activated açaí seeds on the yield of reaction products (bio-oil, gas, H₂O, and biochar), physicochemical properties (acid value, density, and kinematic viscosity) and chemical composition (hydrocarbons and oxygenates) of bio-oil. Catalytic pyrolysis was carried out in a 143 L reactor at temperatures of 350 °C, 400 °C, and 450 °C, 1.0 atmosphere, operating in batch mode. The NaOH activation played a crucial role in modifying the thermal degradation pathway of the biomass, promoting the formation of specific chemical structures and altering the product yields. NaOH acted as a catalyst, enhancing the deoxygenation of the biomass and stimulating the formation of hydrocarbons. As a result, the yields of bio-oil, water, biochar, and gas varied from 5.77 to 7.20% (by mass), 14.90 to 19.77% (by mass), 41 to 54% (by mass), and 25.33 to 32.03%, respectively, influenced by the increase in temperature. FT-IR analyses indicated the presence of characteristic chemical functions of hydrocarbons (alkanes, alkenes, and aromatics) and oxygenated compounds (phenols, cresols, ketones, esters, carboxylic acids, aldehydes, and furans), with an intensification of hydrocarbon signals at higher temperatures. GC-MS analysis identified hydrocarbons and oxygenated compounds as the main chemical classes in the bio-oil, showing a strong dependence on pyrolysis temperature. It was observed that hydrocarbon concentration in bio-oil increased from 49.7% to 57.88% (area) with increasing temperature, while the concentration of oxygenated compounds decreased from 13.88% to 6.69% (area), demonstrating that NaOH activation, combined with temperature elevation, favors the formation of hydrocarbons and the reduction of oxygenated compounds, thereby improving the quality of the produced bio-oil. Full article

(This article belongs to the Special Issue Advances in Heterogeneous Catalysis for Biomass Valorization)

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20 pages, 3005 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Mechanistic Insights into the Formation of Hydrogen Cyanide on Cu-SSZ-13 Zeolites During Ammonia-Assisted Selective Catalytic Reduction in the Presence of Formaldehyde: A Perspective from Ab Initio Energetic Span Modelling

by Shengming Tang, Ning Lu, Peirong Chen and Abhishek Khetan

Catalysts 2026, 16(5), 484; https://doi.org/10.3390/catal16050484 - 21 May 2026

Viewed by 673

Abstract

The emission of hydrogen cyanide (HCN) from formaldehyde (CH₂O) during ammonia-assisted selective catalytic reduction (NH₃-SCR) remains a critical challenge for aftertreatment of bio-hybrid fuel combustion exhaust. The mechanistic details of HCN formation are still poorly understood, especially on widely [...] Read more.

The emission of hydrogen cyanide (HCN) from formaldehyde (CH₂O) during ammonia-assisted selective catalytic reduction (NH₃-SCR) remains a critical challenge for aftertreatment of bio-hybrid fuel combustion exhaust. The mechanistic details of HCN formation are still poorly understood, especially on widely deployed commercial catalysts like Cu-SSZ-13. In this work, we employed density functional theory calculations in combination with the Energetic Span Model to elucidate HCN formation pathways from CH₂O in the presence of NO₂ and H₂O over Cu-SSZ-13. The results revealed the HCN formation pathway with intermediate methylene imine as the dominant one under typical reaction conditions. These findings resonate very well with reports of hexamethylenetetramine (HMT) formation during NH₃-SCR with CH₂O, for which methylene imine is a critical intermediate. Turnover frequency (TOF) estimations highlighted the strong influence of NO₂ and H₂O: higher NO₂ concentrations promoted CO selectivity and suppressed HCN by oxidizing CH₂O to HCOOH, while lower H₂O enhanced HCN formation. These findings establish a detailed mechanistic framework for HCN emission on Cu-SSZ-13 and suggest that controlling NO₂/NO_x ratios and water content can mitigate HCN formation during NH₃-SCR. Full article

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

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19 pages, 2914 KB

Open AccessEditor’s ChoiceArticle

Chlorine-Doped Co₃O₄ Accelerates Interfacial Charge Transfer for Efficient Peroxymonosulfate Activation: Radical-Dominated Bisphenol A Degradation

by Jing Deng, Zhuoyi Pan, Wutao Chen, Kaile Li, Jie Hu and Binbin Shao

Catalysts 2026, 16(5), 483; https://doi.org/10.3390/catal16050483 - 21 May 2026

Viewed by 559

Abstract

Cobalt oxide (Co₃O₄), a transition metal oxide with a cubic spinel structure, shows high potential in peroxymonosulfate (PMS) activation, while its catalytic efficiency is often limited by sluggish interfacial charge transfer. In this study, a chlorine-doped Co₃O [...] Read more.

Cobalt oxide (Co₃O₄), a transition metal oxide with a cubic spinel structure, shows high potential in peroxymonosulfate (PMS) activation, while its catalytic efficiency is often limited by sluggish interfacial charge transfer. In this study, a chlorine-doped Co₃O₄ (Cl-Co₃O₄) was synthesized via a hydrothermal method for the degradation of bisphenol A (BPA) through PMS activation. Systematic characterizations and electrochemical tests demonstrated that chlorine doping could effectively modulate the surface electronic structure of the catalyst, significantly reducing the interfacial charge transfer resistance. Degradation performance evaluations revealed that, compared to pristine Co₃O₄, Cl-Co₃O₄ exhibited a significantly enhanced BPA degradation, achieving near-complete removal of BPA within 15 min under neutral to weakly alkaline conditions. The optimal operational parameters were determined as catalyst dosage of 0.20 g/L, PMS concentration of 0.10 mM and initial pH of 7.0–9.0, with the pseudo-first-order rate constant reaching 0.37 min⁻¹. High-concentration NO₃⁻ showed weak inhibition, while Cl⁻ showed moderate inhibition; 50 mM HCO₃⁻ drastically reduced the rate constant to 0.05 min⁻¹ and almost completely suppressed the reaction. Sulfate (SO₄•⁻) and superoxide (O₂•⁻) radicals were the primary reactive species in this system, explicitly excluding the role of the non-radical electron transfer pathway. Furthermore, three plausible BPA degradation pathways involving C-C bond cleavage, hydroxylation and C-O bond breakage were proposed with 19 intermediates identified. Ecotoxicological assessments based on ECOSAR verified that both acute and chronic toxicity of the intermediates to fish, daphnid and green algae decreased gradually, and the final small-molecule products exhibited significantly lower toxicity than the parent BPA. This study provides a novel strategy for enhancing the PMS activation performance of cobalt-based catalysts by modulating their electronic structures via halogen doping. Full article

(This article belongs to the Special Issue Environmental Functional Materials for Catalytic Degradation of Emerging Contaminants)

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14 pages, 4424 KB

Open AccessArticle

Structure–Activity Relationships in D–π–A Covalent Organic Frameworks for Photocatalytic Water Splitting: Insights from DFT and TD-DFT Calculations

by Hongdi Zhao, Tingting Lv, Mingyue Li, Qingji Wang and Xu Li

Catalysts 2026, 16(5), 482; https://doi.org/10.3390/catal16050482 - 21 May 2026

Viewed by 794

Abstract

Covalent organic frameworks (COFs) are promising crystalline porous polymers for photocatalysis, yet their strong excitonic effects and rapid carrier recombination limit efficiency. However, strong excitonic effects and rapid electron–hole recombination remain key challenges. Herein, we employ density functional theory (DFT) and time-dependent density [...] Read more.

Covalent organic frameworks (COFs) are promising crystalline porous polymers for photocatalysis, yet their strong excitonic effects and rapid carrier recombination limit efficiency. However, strong excitonic effects and rapid electron–hole recombination remain key challenges. Herein, we employ density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to systematically investigate the structure–activity relationships of three D–π–A-type COFs (COF-alkene, TapbBtt-COF, and TtaTpa-COF) for photocatalytic overall water splitting. Benchmarking identifies the M06L functional, SMD solvent model, and 6-311+G(2d,p) basis set as optimal. Our results reveal that molecular planarity, D–π–A configuration, and charge separation collectively govern performance. TtaTpa-COF exhibits the narrowest E_ex (2.47 eV), longest absorption wavelength (502.15 nm), and lowest hole–electron overlap (0.51), enabling efficient carrier separation. For the hydrogen evolution reaction (HER), TtaTpa-COF shows the most favorable *H adsorption free energy (0.04 eV) and lowest LUMO level (−2.8 eV), yielding the highest activity. Notably, the D–π–A system governs active-site selectivity: COF-alkene favors the alkene-linked carbon, whereas the other two favor imine nitrogen. For the oxygen evolution reaction (OER), all follow the adsorbate evolution mechanism with *OOH formation as the rate-determining step. TtaTpa-COF exhibits the lowest limiting potential (4.33 eV), indicating superior water oxidation kinetics. This work establishes a clear structure–activity relationship linking D–π–A architecture to photocatalytic performance, providing a rational design framework for high-activity COF-based photocatalysts. Full article

(This article belongs to the Section Computational Catalysis)

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19 pages, 20103 KB

Open AccessArticle

Synthesis of Interface-Doped Hierarchical Co-MH Z-Scheme Heterojunction for Enhanced Photocatalytic Antibacterial Performance

by Jiahong Gao, Wendan Chen, Jie Lei, Xin Lin and Xuesong Wang

Catalysts 2026, 16(5), 481; https://doi.org/10.3390/catal16050481 - 20 May 2026

Viewed by 1161

Abstract

A Co interface-doped hierarchical magnesium hydroxide (Co-PMH) heterojunction is fabricated by incorporating Co²⁺ into the L-threonate-directed crystallization of Mg(OH)₂ and its subsequent phosphorization. The interface-doped Co narrows the bandgap of magnesium hydroxide, resulting in enhanced visible light conversion and improved broad-spectrum [...] Read more.

A Co interface-doped hierarchical magnesium hydroxide (Co-PMH) heterojunction is fabricated by incorporating Co²⁺ into the L-threonate-directed crystallization of Mg(OH)₂ and its subsequent phosphorization. The interface-doped Co narrows the bandgap of magnesium hydroxide, resulting in enhanced visible light conversion and improved broad-spectrum antimicrobial activity. Under visible light irradiation for 30 min, the Co_0.1-PMH demonstrates an antibacterial efficiency exceeding 97% against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and methicillin-resistant S. aureus (MRSA). Mechanism analysis indicates that the stable doped Co-Mg heterojunction interface brings strong redox capabilities via a Z-scheme charge transfer pathway, driving the generation of ROS (primarily ·OH and ·O₂⁻) to eliminate bacteria adsorbed in situ. Even after three cycles, Co_0.1-PMH maintains high bactericidal activity (>95%) and biocompatibility (>93% cell survival). This makes Co-PMH a promising candidate for antimicrobial infection control. Full article

(This article belongs to the Special Issue Synthesis and Catalytic Applications of Advanced Porous Materials, 2nd Edition)

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13 pages, 8017 KB

Open AccessArticle

Au-SnO_x Hybrid Nanoparticles Encaged in Hollow Mesoporous Silica Nanoreactors for Catalytic Reduction of p-Nitrophenol

by Qifan Zhao, Kaijie Li, Hongbo Yu and Hongfeng Yin

Catalysts 2026, 16(5), 480; https://doi.org/10.3390/catal16050480 - 20 May 2026

Viewed by 353

Abstract

p-nitrophenol (p-NP) is a pollutant with environmental persistence, bioaccumulation potential, and significant health risks, and is widely dispersed in wastewater, so efficient removal of p-NP is imperative. Among the various methods, the catalytic reduction of p-NP to p [...] Read more.

p-nitrophenol (p-NP) is a pollutant with environmental persistence, bioaccumulation potential, and significant health risks, and is widely dispersed in wastewater, so efficient removal of p-NP is imperative. Among the various methods, the catalytic reduction of p-NP to p-aminophenol (p-AP) using sodium borohydride (NaBH₄) is a particularly promising one and, herein, catalysts play a crucial role. Among the various metals, Au shows unique catalytic activity for p-NP reduction. However, nanosized Au often exhibit limited activity and stability due to their high surface free energy. To address this challenge, we designed and synthesized Au-SnO_x hybrid nanoparticles confined within hollow mesoporous silica nanoreactors (Au-SnO_x@hm-SiO₂) via a soft-template-assisted co-adsorption strategy. The resulting bimetallic Au-SnO_x@hm-SiO₂ nanoreactor showed significantly enhanced catalytic activity toward the NaBH₄-mediated reduction of p-nitrophenol (p-NP) compared with its monometallic Au@hm-SiO₂ counterpart, owing to the synergistic effect between Au and SnO_x. Among various Au/Sn ratios, the catalyst with an Au/Sn molar ratio of 1:0.1 demonstrated the highest activity, achieving complete conversion of p-NP within 5 min at a p-NP/Au molar ratio of 529:1—a tenfold improvement over Au@hm-SiO₂. Moreover, the catalyst maintained high efficiency over six consecutive cycles, with only slight deactivation, benefiting from the protective silica shell. Full article

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15 pages, 4232 KB

Open AccessArticle

Fe-Cu Co-Doping Enhanced Peroxymonosulfate Activation for the Degradation of Dimethyl Carbonate in Lithium-Ion Battery Recycling Wastewater

by Shaomeng Huang, Feijian Jing, Liping Wang, Yiqing Xu, Jiawen Sheng and Qiongqiong He

Catalysts 2026, 16(5), 479; https://doi.org/10.3390/catal16050479 - 20 May 2026

Viewed by 437

Abstract

The lithium battery recycling industry is developing rapidly, and the rapid oxidation and degradation of dimethyl carbonate (DMC) in the wastewater generated by this industry is of crucial importance. In this study, Fe and Cu dopants were controlled and the C-SiO₂ framework [...] Read more.

The lithium battery recycling industry is developing rapidly, and the rapid oxidation and degradation of dimethyl carbonate (DMC) in the wastewater generated by this industry is of crucial importance. In this study, Fe and Cu dopants were controlled and the C-SiO₂ framework with porous structures was constructed to synthesize FeCuC-SiO₂ and C-SiO₂ catalysts. The former could achieve 91.65% of DMC degradation within 60 min through peroxymonosulfate (PMS) activation, and the degradation rate was increased to 4.44 times compared to C-SiO₂ without Fe and Cu doping. And under optimized conditions, a DMC degradation rate of 90.57% can be achieved within 10 min by FeCuC-SiO₂. The catalyst has good stability and the catalytic activity can be maintained during reuse process for five times with over 70% of DMC degradation rate, 58.9% of mineralization rate, and a relatively low amount of metal leaching. Moreover, the degradation rate can still remain above 70% with the existence of impurity anions, demonstrating a strong salt resistance. Hydroxyl radicals (OH^•), sulfate radicals (SO₄^•−), and ¹O₂ were found to dominant the reaction in the FeCuC-SiO₂-PMS system, which were involved in both free radical and non-free radical pathways and led to excellent catalytic oxidation performance and environmental adaptability. In general, a novel design for a Fenton-like catalyst was presented, providing a theoretical basis for the improvement of oxidation efficiency and the regulation of reaction pathways in Fenton-like reactions. Full article

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28 pages, 9559 KB

Open AccessReview

Non-Radical Catalytic Ozonation for Wastewater Treatment: Evidence Standards, Bromate Trade-Offs, and Scale-Up Constraints

by Xiongwei Liang, Shaopeng Yu, Yongfu Ju, Yingning Wang, Haoran Lü and Lixin Li

Catalysts 2026, 16(5), 478; https://doi.org/10.3390/catal16050478 - 20 May 2026

Viewed by 691

Abstract

Heterogeneous catalytic ozonation has attracted increasing research attention as a strategy for advanced wastewater polishing; yet the recent literature has advanced the attribution of non-radical pathways at a pace that has outstripped rigorous demonstration of their practical process advantage. This article constitutes an [...] Read more.

Heterogeneous catalytic ozonation has attracted increasing research attention as a strategy for advanced wastewater polishing; yet the recent literature has advanced the attribution of non-radical pathways at a pace that has outstripped rigorous demonstration of their practical process advantage. This article constitutes an evidence-centered critical review—rather than a formal systematic review—organized around a central evaluative question: under what conditions are non-radical mechanistic claims in catalytic ozonation sufficiently persuasive, wastewater-relevant, and defensible to warrant consideration for process translation. Recent studies, drawn primarily from the period 2023–2026, are evaluated through an explicit evidence-grading framework that distinguishes among radical, singlet-oxygen-mediated, surface-bound oxygen-transfer, direct electron-transfer, and high-valent metal-oxo pathways. The review further examines whether reported parent-compound removal is corroborated by complementary lines of evidence encompassing bromate formation, transformation product characterization, effluent toxicity assessment, catalyst leaching quantification, operational durability, and reactor-scale performance. The synthesis reveals that single-atom catalysts currently provide the most robust active-site mechanistic evidence; however, even these systems remain constrained by their reliance on simplified aqueous matrices, incomplete transformation byproduct accounting, and unresolved long-term stability. Accordingly, the article proposes standardized reporting protocols and benchmark performance metrics—including a bromate-normalized treatment benefit index—to delineate mechanistic elegance from process realism. Full article

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

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40 pages, 6229 KB

Open AccessArticle

Magnetized Cow Bone-Derived Char–Alginate Hydrogel Beads for Catalytic Degradation of β-Blocker Drug Nadolol and Treatment of Real Pharmaceutical Wastewater in a Periodate-Activated Continuous-Flow Fluidized-Bed Photoreactor

by Hassan Shokry, Hanan Alhussain, Arafat Toghan, Emad M. Masoud, Karim Amer, Marwa Elkady, Mahmoud Samy and Mohamed Mohamed Gaber

Catalysts 2026, 16(5), 477; https://doi.org/10.3390/catal16050477 - 20 May 2026

Viewed by 556

Abstract

Here, the degradation of a β-blocker drug (Nadolol (NAD)) and real pharmaceutical wastewater was achieved using magnetized cow bone waste-derived char (MCBWC)–alginate hydrogel beads via a periodate (PI) activation system in a continuous-flow fluidized-bed photoreactor. The removal of NAD by PI-based degradation systems [...] Read more.

Here, the degradation of a β-blocker drug (Nadolol (NAD)) and real pharmaceutical wastewater was achieved using magnetized cow bone waste-derived char (MCBWC)–alginate hydrogel beads via a periodate (PI) activation system in a continuous-flow fluidized-bed photoreactor. The removal of NAD by PI-based degradation systems has not been previously reported, and the degradation of real industrial wastewater in continuous-flow photoreactors remains underexplored. The fabricated beads exhibited a high surface area of 78.58 m² g⁻¹, a total pore volume of 0.19 cm³ g⁻¹, and an effective integration of all composite components. The MCBWC–alginate hydrogel beads/PI/light degradation system degraded 71.47% of NAD, which was higher than that of the sole photocatalysis and PI activation systems. Further, the optimal operating condition could achieve a NAD degradation efficiency of 97.1% and a total organic carbon (TOC) removal efficiency of 82.78%. Furthermore, the degradation system demonstrated the non-formation of toxic iodinated byproducts. The hydrogel beads demonstrated high stability, where the NAD degradation efficiency slightly decreased by only 2.85% across five successive experiments. Singlet oxygen and iodine-based radicals contributed to NAD degradation more than other reactive species. Bicarbonate showed the highest suppressive effect on the degradation performance, while adding 10 mg L⁻¹ of humic acid decreased the degradation efficiency to 85.58%. The degradation system could further degrade other pharmaceuticals (e.g., ibuprofen, paracetamol, carbamazepine, tetracycline) and real pharmaceutical wastewater, attaining 78.37% degradation efficiency of NAD and 44.25% TOC mineralization. This study presents a stable, effective, and continuous degradation system that can be employed in real-world industrial wastewater treatment applications. Full article

(This article belongs to the Special Issue From Photocatalysts to Photoreactors: Scalable and Sustainable Technologies for Water Treatment)

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17 pages, 2662 KB

Open AccessArticle

Combustion and Emission Characteristics of Diesel Fuel Enhanced with Ternary Ag/CeO₂/TiO₂ Nanocatalysts

by Hatem Abdussalam M Aboud and Songül Kaskun Ergani

Catalysts 2026, 16(5), 476; https://doi.org/10.3390/catal16050476 - 20 May 2026

Viewed by 449

Abstract

Diesel engines are commonly used in transportation and power generation, but their operation is associated with incomplete combustion and emissions. In this research, four different nanocatalyst additives including Ag, Ag/TiO₂, Ce/TiO₂, and Ag/CeO₂/TiO₂ were studied as [...] Read more.

Diesel engines are commonly used in transportation and power generation, but their operation is associated with incomplete combustion and emissions. In this research, four different nanocatalyst additives including Ag, Ag/TiO₂, Ce/TiO₂, and Ag/CeO₂/TiO₂ were studied as diesel fuel additives to improve combustion efficiency and minimize regulated emissions. These nanoparticles were synthesized and characterized by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques. The prepared fuel blends were tested in a single-cylinder diesel engine at additive concentrations of 50, 75, and 100 ppm under varying engine loads. Among the tested formulations, the ternary Ag/CeO₂/TiO₂ blend demonstrated the highest performance. When compared with the baseline diesel fuel, it reduced CO emissions by 32.5%, HC emissions by 27.8%, and NO_x emissions by 29.4%. At the same time, the amount of CO₂ emission has increased by 18.81%, which shows that the combustion is more complete. Also, the same formulation has decreased brake-specific fuel consumption (BSFC) by 18.7% and increased brake thermal efficiency (BTE) by 16.3%. The improved performance is due to the cooperative effect of CeO₂ oxygen buffering, TiO₂ surface-assisted oxidation, and oxidation activity of the silver species. The findings show that the ternary nanocatalyst formulation is an effective approach for optimizing diesel fuel combustion and emissions. Full article

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25 pages, 2628 KB

Open AccessReview

Advanced Electrolytic Water Catalysts: A Key Technology Empowering China’s “Dual Carbon” Strategy

by Xueyan Zheng, Zongtai Zhou, Jing Wang, Zikang Zhao and Junshuang Zhou

Catalysts 2026, 16(5), 475; https://doi.org/10.3390/catal16050475 - 20 May 2026

Cited by 1 | Viewed by 649

Abstract

Hydrogen energy is an important carrier for achieving China’s “dual carbon” goals, and one of the sources of green hydrogen is to develop better water electrolysis catalysts. This paper reviews the current research status of water electrolysis hydrogen production catalysts, analyzes the role [...] Read more.

Hydrogen energy is an important carrier for achieving China’s “dual carbon” goals, and one of the sources of green hydrogen is to develop better water electrolysis catalysts. This paper reviews the current research status of water electrolysis hydrogen production catalysts, analyzes the role and significance of advanced hydrogen energy catalysts in achieving the “dual carbon” goals, and conducts an in-depth analysis of the difficulties in moving from the laboratory to large-scale application, namely, how to bridge the “four gaps”, including catalyst performance evaluation, long-term application of catalysts, macro-scale preparation, and device integration. It also proposes overall improvement ideas and measures. In this paper, effective improvement methods are proposed for these “four gaps”, which can improve the relevant indicators and service life of water electrolysis hydrogen production catalysts, further promote the large-scale production and industrial application of green hydrogen, and provide a strong guarantee for solving China’s “dual carbon” problems. Full article

(This article belongs to the Special Issue Catalysis and New Energy Materials)

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4 pages, 166 KB

Open AccessEditorial

Advances in Photoassisted and Photocatalytic Processes for Water Remediation

by Jaime Carbajo and Patricia García-Muñoz

Catalysts 2026, 16(5), 474; https://doi.org/10.3390/catal16050474 - 20 May 2026

Viewed by 382

Abstract

Since heterogeneous photocatalysis emerged as a promising approach able to harness light energy—ideally solar radiation—to drive oxidation and reduction as effective technologies for water remediation under mild conditions [...] Full article

(This article belongs to the Special Issue Advances in Photoassisted and Photocatalytic Processes for Water Remediation)

30 pages, 15159 KB

Open AccessEditor’s ChoiceArticle

Experimental Study on the Influence of Metal Oxide Catalyst Performance in Sulfur Compounds Removal from Natural Gas

by Samuel Antwi, William Holmes, Dongmei Cao, Dhan Fortela, Tolga Karsili, Emmanuel Revellame, August Gallo, Mark Zappi and Rafael Hernandez

Catalysts 2026, 16(5), 473; https://doi.org/10.3390/catal16050473 - 19 May 2026

Viewed by 694

Abstract

The removal of sulfur compounds such as ethyl mercaptan from natural gas remains a critical challenge due to their detrimental effects on downstream processes, catalyst poisoning, and environmental emissions. In this study, a series of halloysite-supported transition metal oxide catalysts was synthesized and [...] Read more.

The removal of sulfur compounds such as ethyl mercaptan from natural gas remains a critical challenge due to their detrimental effects on downstream processes, catalyst poisoning, and environmental emissions. In this study, a series of halloysite-supported transition metal oxide catalysts was synthesized and evaluated for the removal of sulfur compounds from natural gas at 25 °C, 200 psi, and 36 mL/min, using 0.5 g of the catalyst. The nanotubular structure and dual surface chemistry of halloysite promote enhanced metal dispersion and improved mass transfer. Single-metal (manganese, copper, zinc, and nickel) catalysts were developed and tested, after which a multi-metal oxide (base) catalyst comprising a composite of the single metals (Zn-Cu-Mn-Ni) was developed as a base catalyst to combine adsorption-active and redox-active functionalities, and its performance was further enhanced by the addition of palladium as promoter. A combination of analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), provided evidence that highly dispersed metal oxide phases were formed and the halloysite structure was preserved. XPS data showed the presence of oxidation states of metals that were active (Zn²⁺, Cu²⁺, Ni²⁺, Mn³⁺/Mn⁴⁺ and Pd²⁺), an indication of a redox-active surface for sulfur interaction. Results from the breakthrough experiments showed that the base catalyst significantly improved sulfur removal compared to single-metal catalysts, while the Pd-promoted catalyst exhibited the highest performance, with a breakthrough time of 630 min. Palladium was incorporated at low loading as a promoter, enhancing adsorption performance while maintaining a favorable balance between efficiency and material cost. This enhancement is attributed to synergistic interactions between adsorption-active sites and redox-active species, as well as improved electron transfer facilitated by palladium. The results demonstrate that rational design of multi-metal oxide catalysts supported on naturally occurring halloysite provides an effective and scalable approach for sulfur removal from natural gas, with strong potential for industrial applications. Full article

(This article belongs to the Special Issue Designing Catalytic Desulfurization Processes to Prepare Clean Fuels, 3rd Edition)

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33 pages, 1199 KB

Open AccessReview

Advances in Catalytic Materials for Wastewater Treatment: Design Strategies and Reaction Mechanisms

by Qing Xu, Wenwen Liu, Linhong Xie, Jiayi Shao, Leihe Cai, Wenhao Lv, Haowei Li, Shengxian Xian and Yujian Wu

Catalysts 2026, 16(5), 472; https://doi.org/10.3390/catal16050472 - 19 May 2026

Cited by 2 | Viewed by 1160

Abstract

With the growing severity of water pollution, conventional treatment technologies are increasingly unable to satisfy the demand for deep purification. Catalytic wastewater treatment has emerged as an effective strategy for degrading refractory pollutants because of its high efficiency, mild operating conditions, and environmentally [...] Read more.

With the growing severity of water pollution, conventional treatment technologies are increasingly unable to satisfy the demand for deep purification. Catalytic wastewater treatment has emerged as an effective strategy for degrading refractory pollutants because of its high efficiency, mild operating conditions, and environmentally friendly nature. This review systematically summarizes recent progress in catalytic materials for wastewater treatment, covering four major categories: metal-based materials, carbon-based materials, multicomponent composites, and photo/electrocatalytic systems. Particular attention is given to their design strategies, structural characteristics, and performance advantages. On this basis, the full mechanistic chain is discussed, from interfacial adsorption and activation to reactive-species generation, including both radical and non-radical pathways, intermediate transformation, and macroscopic reaction kinetics. The review also highlights representative applications in practical wastewater streams, including textile dyeing and pharmaceutical, chemical, landfill leachate, and municipal tailwater treatment, thereby demonstrating the engineering potential of catalytic technologies. At the same time, several critical challenges remain, including insufficient long-term material stability, incomplete mechanistic understanding in complex water matrices, limited adaptability to real wastewater, and the high cost of large-scale preparation. Future research should therefore focus on the development of highly stable, low-cost, and interference-resistant catalytic materials, deeper mechanistic elucidation through in situ characterization and theoretical calculations, stronger integration with membrane separation, biological treatment, photovoltaic or electrochemical processes, and the establishment of standardized evaluation protocols and life-cycle assessment frameworks. These efforts will accelerate the transition of catalytic wastewater treatment toward greener, smarter, and more practical engineering applications. Full article

(This article belongs to the Special Issue Next-Generation Catalytic Solutions for Water Purification and Wastewater Remediation)

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16 pages, 2332 KB

Open AccessReview

Recent Advances in Cellular Synthesis of Structured Triacylglycerols

by Jiayi Yang, Siyang Liu and Junfeng Liu

Catalysts 2026, 16(5), 471; https://doi.org/10.3390/catal16050471 - 19 May 2026

Viewed by 360

Abstract

Triacylglycerols (TAGs) are essential energy reservoirs and industrial raw materials, while structured TAGs (STAGs) with tailored fatty acid distributions possess unique nutritional and functional values but low natural abundance. Enzymatic synthesis is strictly limited by feedstock and cost, making microbial de novo synthesis [...] Read more.

Triacylglycerols (TAGs) are essential energy reservoirs and industrial raw materials, while structured TAGs (STAGs) with tailored fatty acid distributions possess unique nutritional and functional values but low natural abundance. Enzymatic synthesis is strictly limited by feedstock and cost, making microbial de novo synthesis via metabolic engineering a promising alternative. This review summarizes advances in the fatty acid biosynthesis pathway and its regulation, key enzymes in TAG synthesis (GPAT, LPAAT, and DGAT), and microbial production of major STAGs (OPO, MLM, CBEs, and PUFA-rich STAGs). Current challenges and future perspectives are also discussed, promoting the shift toward rational design of functional STAGs. Full article

(This article belongs to the Section Biocatalysis)

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17 pages, 3984 KB

Open AccessArticle

Photocatalytic Degradation of Polycyclic Aromatic Hydrocarbons in Simulated Offshore Oil Spill Wastewater by Magnesium Phthalocyanine Derivatives Supported on Coconut Shell Activated Carbon

by Dejun Wang, Hui Li, Lihua Liang, Juan Su, Jifang Wei, Dong Wang, Changjiang Zuo and Qiyou Liu

Catalysts 2026, 16(5), 470; https://doi.org/10.3390/catal16050470 - 19 May 2026

Viewed by 501

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic pollutants in marine ecosystems, necessitating efficient remediation. This study synthesized magnesium phthalocyanine (MgPc) and its modified derivatives, magnesium azaphthalocyanine (NMgPc) and methyl-substituted magnesium azaphthalocyanine (MeNMgPc), as visible-light-driven photocatalysts for PAH degradation. To enhance efficiency and recoverability, [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic pollutants in marine ecosystems, necessitating efficient remediation. This study synthesized magnesium phthalocyanine (MgPc) and its modified derivatives, magnesium azaphthalocyanine (NMgPc) and methyl-substituted magnesium azaphthalocyanine (MeNMgPc), as visible-light-driven photocatalysts for PAH degradation. To enhance efficiency and recoverability, these photosensitizers were immobilized onto coconut shell activated carbon (AC) via multiple ultrasonic impregnation. Characterizations (UV-Vis, SEM, EDAX, BET) confirmed successful active component deposition; nitrogen substitution and peripheral methyl groups synergistically tuned the electronic structure and suppressed aggregation. Under xenon lamp irradiation, the MeNMgPc/C composite exhibited superior activity, degrading 90.55% of naphthalene. Box-Behnken response surface optimization identified optimal conditions (13.18 g/L dosage, 20 A, 2.28 h), yielding 96.67% experimental removal and adhering to pseudo-first-order kinetics. Mechanistic studies via electron spin resonance identified hydroxyl (•OH) and superoxide radicals (O₂^•−) as primary reactive species. GC-MS analysis elucidated a sequential phenanthrene ring-opening pathway, progressing to ultimate mineralization into CO₂. Consequently, MeNMgPc/C presents a highly efficient, recoverable photocatalytic platform for marine PAH remediation. Full article

(This article belongs to the Special Issue Catalytic Materials for Hazardous Wastewater Treatment)

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10 pages, 1306 KB

Open AccessArticle

Ab Initio Investigation of the M Segregation on PdM (M = Co, Ru, Pt) Alloys with Chemisorbed Atomic Oxygen

by Yanlin Yu, Yuanxun Li, Yufeng Wen, Renmei Zhang and Qiuling Huang

Catalysts 2026, 16(5), 469; https://doi.org/10.3390/catal16050469 - 18 May 2026

Viewed by 370

Abstract

Surface segregation in metal alloys critically determines their electrocatalytic performance, yet how chemisorbed oxygen alters segregation behavior under reaction conditions remains poorly understood. Using density functional theory, we quantify the segregation energies on the (111) surface of PdM (M = Co, Ru, Pt) [...] Read more.

Surface segregation in metal alloys critically determines their electrocatalytic performance, yet how chemisorbed oxygen alters segregation behavior under reaction conditions remains poorly understood. Using density functional theory, we quantify the segregation energies on the (111) surface of PdM (M = Co, Ru, Pt) alloys with chemisorbed atomic oxygen. In vacuum, all three alloying elements exhibit positive segregation energies (0.28 eV for Co, 0.40 eV for Ru, and 0.04 eV for Pt) on the topmost layer, indicating that surface segregation is energetically unfavorable. Upon oxygen adsorption, however, this trend reverses for Co and Ru: their segregation energies shift by −0.18 eV and −0.33 eV, respectively, driving these atoms strongly toward the surface. In contrast, Pt shows only a marginal shift of 0.03 eV, retaining its preference for the bulk. Further analysis of oxygen adsorption and the associated electronic structure reveals that the strength of surface–adsorbate binding governs these segregation trends under reactive conditions. The present work offers a theoretical foundation for the rational design of Pd-based alloy catalysts for applications such as the hydrogen evolution reaction. Full article

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21 pages, 7188 KB

Open AccessArticle

A Visible-Light-Active TiO₂/Bi₂O₃/g-C₃N₄ Heterojunction: Synthesis, Photocatalytic Degradation of Rhodamine B, and Antibacterial Activity

by Lotfi Mouni, Oumnia Kasrani, Zakari Kheznadji, Nasma Bouchelkia, Abdelwahab Rai, Gianluca Viscusi, Abdelhak Khachay, Farid Ait Merzeg, Tarek H. Taha, Gharieb S. El-Sayyad and Hamdi Bendif

Catalysts 2026, 16(5), 468; https://doi.org/10.3390/catal16050468 - 18 May 2026

Cited by 3 | Viewed by 811

Abstract

Ternary heterojunction photocatalysts enhance the separation and transport of photogenerated charge carriers, thereby boosting their redox activity for use in environmental and sustainable energy applications. This study focuses on the synthesis of a TiO₂/Bi₂O₃/g-C₃N₄ [...] Read more.

Ternary heterojunction photocatalysts enhance the separation and transport of photogenerated charge carriers, thereby boosting their redox activity for use in environmental and sustainable energy applications. This study focuses on the synthesis of a TiO₂/Bi₂O₃/g-C₃N₄ heterojunction composite via a ceramic method with TiO₂ loadings of 80%, 85%, and 90% (denoted 80T-BC, 85T-BC, and 90T-BC, respectively) to investigate structure–property–performance relationships in photocatalytic dye degradation. The structural, optical, and morphological properties of the synthesised materials were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance UV–Vis spectroscopy (DRS). The photocatalytic performance was evaluated by measuring the degradation of Rhodamine B under visible light irradiation. Under optimised conditions (pH 6, initial RhB concentration of 5 mg/L, and a reaction time of 120 min), a degradation rate of 99% was achieved. Furthermore, the semiconductor demonstrated significant antibacterial activity against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. This study presents a promising strategy for modifying TiO₂-based semiconductors by incorporating different metal oxides. The formation of the resulting heterojunction significantly enhances photocatalytic efficiency, demonstrating strong potential for practical environmental remediation. Full article

(This article belongs to the Special Issue Catalytic Processes in Environmental Applications)

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15 pages, 4507 KB

Open AccessArticle

Synthesis and Characterization of Silver-Doped TiO₂ Nanocomposite Using Diethanolamine as Solvent: Photocatalytic Performance for Organic Dye Degradation and Antimicrobial Activity

by Muhammad Bilal, Nasim Ullah, Javed Ali, Zarshad Ali, Adeel Ahmed, Bushra Adalat, Sher Bahadar Khan, Kalsoom Akhtar and Esraa M. Bakhsh

Catalysts 2026, 16(5), 467; https://doi.org/10.3390/catal16050467 - 18 May 2026

Viewed by 542

Abstract

In this research work, Ag-doped and undoped TiO₂ nanocomposites were prepared through a sol–gel method, using diethanolamine as a solvent. From the evolution of various characterized techniques (XRD, FT-IR, SEM and TGA analysis), it was found that Ag-TiO₂ nanocomposites have a [...] Read more.

In this research work, Ag-doped and undoped TiO₂ nanocomposites were prepared through a sol–gel method, using diethanolamine as a solvent. From the evolution of various characterized techniques (XRD, FT-IR, SEM and TGA analysis), it was found that Ag-TiO₂ nanocomposites have a mixture of rutile and anatase phases of titania. The catalytic performance of the Ag-TiO₂ nanocomposites was evaluated for Eriochrome Black T (EBT) photodegradation. To determine the photocatalytic efficiency of the nanocomposites, different factors including pH (2–12), catalytic dose (2–12 mg), reaction time (0–180 min) and concentration (2–10 mg/L) were investigated. The calcined Ag-TiO₂ showed high degradation (94%) for EBT at a low pH for 0.01 g of catalyst using 10 mg/L of dye solution. The kinetic study revealed that the photocatalytic degradation process obeys pseudo second-order kinetics. To investigate antibacterial effects, different bacteria such as Enterococcous, Staph Avrius, serritia and Escherichia E. coli were utilized. A total of 200 mg of calcined Ag-TiO₂ nanocomposite showed optimum activities against bacterial strains. Full article

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

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13 pages, 2779 KB

Open AccessArticle

Boosting Toluene Oxidation Performance of CoAl₂O₄ Catalysts by Incorporating the Synergistic Co³⁺-Ov Sites

by Dadao Wang, Xueqin Yang, Menglan Xiao, Xiuhong Zhu, Guangxin Ru, Xiaohua Cao, Xiaolin Yu and Maofa Ge

Catalysts 2026, 16(5), 466; https://doi.org/10.3390/catal16050466 - 16 May 2026

Viewed by 534

Abstract

Volatile organic compounds can aggravate the atmospheric pollution and health risks due to their high toxicity and photochemical reactivity. Herein, a series of cobalt aluminate spinel catalysts with high efficiency was fabricated via a cost-efficient solvothermal method. Plentiful oxygen vacancies with negative charge [...] Read more.

Volatile organic compounds can aggravate the atmospheric pollution and health risks due to their high toxicity and photochemical reactivity. Herein, a series of cobalt aluminate spinel catalysts with high efficiency was fabricated via a cost-efficient solvothermal method. Plentiful oxygen vacancies with negative charge were introduced adjacent to the octahedrally coordinated Co³⁺ species in CoAl₂O₄ catalysts, thereby generating the synergetic Co³⁺-oxygen vacancy (Ov) sites, which facilitated the rapid activation and migration of oxygen species. Accordingly, the superior catalytic activity was observed for 1Al-1Co even with lower cobalt due to the presence of abundant Co³⁺-Ov sites, revealing the predominant roles of synergetic sites in the toluene oxidation. Moreover, the 1Al-1Co catalyst exhibited the optimal intrinsic catalytic performance with the lowest activation energy of 161.2 kJ·mol⁻¹ and the highest specific toluene reaction rate of 3.18 × 10⁻⁵ mmol·h⁻¹·m⁻². In situ DRIFTS results further verified that oxygen vacancies and active Co³⁺ species could synergistically boost highly reactive oxygen species, which rapidly oxidize benzoate into maleic anhydride, achieving the efficient complete oxidation of toluene. Full article

(This article belongs to the Special Issue Catalytic Removal of Volatile Organic Compounds (VOCs))

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17 pages, 2445 KB

Open AccessArticle

Metal-Doped TiO₂ Optical Fiber Textiles for Concurrent Removal of Airborne Bacteria and Volatile Organic Compounds

by Amine Aymen Assadi, Youcef Serhane, Mohammod Hafizur Rahman, Mohamed Aziz Hajjaji, Abdelkrim Bouzaza, Hichem Tahraoui, Jie Zhang and Abdeltif Amrane

Catalysts 2026, 16(5), 465; https://doi.org/10.3390/catal16050465 - 16 May 2026

Viewed by 506

Abstract

This study focuses on the application of photocatalysis for air pollution, targeting both chemical and biological contaminants. The selected target compounds were 3-methylbutan-1-ol (C₅H₁₂O), a volatile organic compound abundantly generated in the food industry, and Escherichia coli, representing [...] Read more.

This study focuses on the application of photocatalysis for air pollution, targeting both chemical and biological contaminants. The selected target compounds were 3-methylbutan-1-ol (C₅H₁₂O), a volatile organic compound abundantly generated in the food industry, and Escherichia coli, representing a relevant bacterial indicator commonly encountered in such industrial environments and effectively embodying a biological threat. In this work, a series of experiments was conducted in a batch reactor using a novel TiO₂-based photocatalytic system integrating metal wires, namely copper (Cu) and silver (Ag), woven into an optical fiber support. A comparative evaluation of photocatalytic performance across different media was carried out for the removal of 3-methylbutan-1-ol, as well as for E. coli deactivation. The results demonstrated notable performance of the TiO₂-Cu medium for chemical treatment, achieving 97% removal efficiency after 85 min at an inlet concentration of 28 mg·m⁻³. Similarly, significant antibacterial activity was observed with 5.50 log reduction in colony-forming units (CFU) after 2.5 h. The photocatalytic performance of TiO₂-Cu supports was further validated under different operating conditions, including relative humidity levels ranging from 20% to 60% and concentration range from 5–30 mg·m⁻³. Finally, this study also includes a comparison between the TiO₂-Cu support and conventional photocatalytic systems based on TiO₂, particularly for simultaneous (combined) treatment of chemical and biological contaminants, with promising and encouraging outcomes. Full article

(This article belongs to the Special Issue Effect of the Modification of Catalysts on the Catalytic Performance, 3rd Edition)

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19 pages, 4706 KB

Open AccessFeature PaperArticle

Engineering Polyaniline Nanofibers/TiO₂ for Enhanced Photocatalytic Degradation of Organic Contaminants: In-Depth Structural and Mechanistic Insights

by Mohamed. A. Diab, Heba A. El-Sabban and Youngsoo Kim

Catalysts 2026, 16(5), 464; https://doi.org/10.3390/catal16050464 - 16 May 2026

Cited by 1 | Viewed by 1196

Abstract

This study presents the rational design of a visible-light-responsive TiO₂/polyaniline (PANI) nanofiber heterostructure via in situ oxidative polymerization to overcome the limited visible-light absorption and rapid charge recombination of TiO₂. Comprehensive characterization using XRD, FT-IR, XPS, SEM, UV–Vis DRS, [...] Read more.

This study presents the rational design of a visible-light-responsive TiO₂/polyaniline (PANI) nanofiber heterostructure via in situ oxidative polymerization to overcome the limited visible-light absorption and rapid charge recombination of TiO₂. Comprehensive characterization using XRD, FT-IR, XPS, SEM, UV–Vis DRS, and EIS confirmed the successful integration of TiO₂ nanoparticles within a conductive polyaniline nanofiber network, enabling efficient interfacial charge transfer. The optimized TiO₂/PANI-30 composite exhibited outstanding photocatalytic performance, achieving ~99% degradation of Basic Fuchsin dye within 40 min under visible light, significantly outperforming pristine TiO₂. The enhanced activity is attributed to improved visible-light absorption, reduced bandgap energy, and suppressed electron–hole recombination, supported by optical and electrochemical analyses. Kinetic studies indicated pseudo-first-order behavior, with TiO₂/PANI-30 showing the highest rate constant. Radical trapping experiments identified superoxide and hydroxyl radicals as the main active species, with •OH playing a dominant role. A direct Z-scheme charge transfer mechanism was suggested, preserving strong redox potentials and promoting reactive oxygen species generation. Additionally, the photocatalyst demonstrated excellent stability and reusability. These findings highlight the suggested potential of TiO₂/PANI systems as efficient and sustainable photocatalysts for wastewater treatment. Full article

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19 pages, 4999 KB

Open AccessArticle

Tailoring Active-Site Density in Ni/Al-MCM-41 Catalysts for Ethanol-Assisted CO₂ Reforming: Impact of Ni Loading on Catalytic Performance

by Fatima Seerat, Muhammad Azriel Irfan Bin Azhar, Alaa Dhari Jawad Al-Bayati, Sarah R. Al-Karkhi, Zainab Y. Shnain and Bamidele Victor Ayodele

Catalysts 2026, 16(5), 463; https://doi.org/10.3390/catal16050463 - 16 May 2026

Viewed by 526

Abstract

The interest in more sustainable energy sources has necessitated research in hydrogen production from various reliable pathways. This study investigates the potential of hydrogen production by ethanol-assisted CO₂ reforming over Al-MCM-41-supported Ni catalysts considering the effect on the catalytic performance and stability. [...] Read more.

The interest in more sustainable energy sources has necessitated research in hydrogen production from various reliable pathways. This study investigates the potential of hydrogen production by ethanol-assisted CO₂ reforming over Al-MCM-41-supported Ni catalysts considering the effect on the catalytic performance and stability. The Ni/Al-MCM-41 catalysts were synthesized via wet impregnation method and characterized using different instruments and techniques. Evidence of the formation of well-crystallized Ni nanoparticles dispersed on the Al-MCM-41 support was confirmed by X-ray diffraction analysis and field emission scanning electron microscopy. The amount of Ni loading, which varied from 5 to 15%, was confirmed using energy-dispersive analysis, while the mesoporous nature of the Ni/Al-MCM-41 was ascertained using N₂ physisorption analysis. The performance of the Ni/Al-MCM-41 catalyst as a function of the ethanol conversion, CO₂ conversion, hydrogen and CO yield is strongly corrected with Ni loading and reaction temperature. The ethanol conversion and hydrogen yield increase with the increase in reaction temperature. At a reaction temperature of 550 °C the lowest ethanol conversion and hydrogen yield of 32.3% and 33.7% were obtained over the 5 wt% Ni/Al-MCM-41 catalyst, while the highest ethanol conversion of 87.4% and hydrogen yield of 75.5% were obtained over the 15% Ni/Al-MCM-41 at 700 °C. The 15 wt% catalyst achieves the most balanced syngas profile at 700 °C, where the H₂ and CO yields are optimized through the synergistic consumption of both ethanol and CO₂. It can be inferred that the reaction follows a bifunctional pathway whereby the Ni active sites are responsible for the ethanol dissociation while the CO₂ adsorption and activation are enhanced by the Al-MCM-41 support. Full article

(This article belongs to the Special Issue 15th Anniversary of Catalysts—Industrial Development of Catalytic Materials for the Energetic Transition)

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14 pages, 2066 KB

Open AccessArticle

Axial Coordination Modulation of FeN₄ Sites in Dioxin-Linked Covalent Organic Hybrid Catalysts for Enhanced ORR Activity and Zinc–Air Battery Application

by Danyang Zhu, Baolong Liu, Yiping Mo, Qiao Zhang, Yuhan Ma, Wenqi Dai and Wangyang Lu

Catalysts 2026, 16(5), 462; https://doi.org/10.3390/catal16050462 - 15 May 2026

Viewed by 448

Abstract

Effective regulation of the adsorption strength of oxygen reduction reaction (ORR) intermediates on active sites is the key to enhancing their catalytic performance. This study proposes an axial coordination modulation strategy by successfully anchoring the dioxin-linked FePcF₁₆-based covalent organic frameworks (COFs) [...] Read more.

Effective regulation of the adsorption strength of oxygen reduction reaction (ORR) intermediates on active sites is the key to enhancing their catalytic performance. This study proposes an axial coordination modulation strategy by successfully anchoring the dioxin-linked FePcF₁₆-based covalent organic frameworks (COFs) onto amino-functionalized multi-walled carbon nanotubes (NH₂-MWCNTs), constructing a FePcF₁₆-COF/NH₂-MWCNT hybrid catalyst. Experimental results demonstrate that the catalyst exhibits outstanding ORR activity (E_1/2 = 0.901 V; J_L = 5.133 mA cm⁻²), outperforming commercial 20% Pt/C and most reported Fe-based non-precious metal catalysts. Furthermore, the robust dioxin-linked COF skeleton endows the catalyst with excellent electrochemical stability. A zinc–air battery using this catalyst as the cathode also demonstrates superior power density and cycling performance. This work provides a new strategy for designing highly efficient ORR catalysts through axial coordination environment engineering. Full article

(This article belongs to the Special Issue Catalysis and New Energy Materials)

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8 pages, 4170 KB

Open AccessEditor’s ChoiceArticle

Porous Ru-Doped Double Perovskite Oxide as a High-Performance Electrocatalyst for the Oxygen Evolution Reaction

by Junbo Wang, Zhijiao Wang, Qi Tang, Yin Zhang, Xiaoyu Deng, Yang Wang and Kaiteng Wang

Catalysts 2026, 16(5), 461; https://doi.org/10.3390/catal16050461 - 15 May 2026

Viewed by 521

Abstract

The oxygen evolution reaction (OER) constitutes a critical bottleneck in water electrolysis for hydrogen production owing to its sluggish four-electron transfer kinetics. Double perovskite oxides (A₂BB’O₆) have emerged as exceptional OER catalysts distinguished by their stable crystal frameworks and [...] Read more.

The oxygen evolution reaction (OER) constitutes a critical bottleneck in water electrolysis for hydrogen production owing to its sluggish four-electron transfer kinetics. Double perovskite oxides (A₂BB’O₆) have emerged as exceptional OER catalysts distinguished by their stable crystal frameworks and flexible active-site tunability. Crucially, the alternating ordering of B and B’ cations at octahedral positions creates a unique lattice enriched with oxygen vacancies. Leveraging these intrinsic structural advantages, we synthesized a porous Ru-doped double perovskite oxide Sr₂Fe_1.9Ru_0.1O_6-δ (SFRO-850) featuring increased oxygen vacancies via a sol–gel route. Electrochemical measurement shows that SFRO-850 exhibits outstanding OER activity with a low overpotential of 326 mV at a current density of 10 mA cm⁻² and a Tafel slope of 67.48 mV dec⁻¹, superior to the undoped material and its counterparts. The results validate the efficacy of the double perovskite framework as a superior platform for hosting catalytically active sites, offering a viable pathway toward high-performance, low-noble-metal-content OER catalysts. Full article

(This article belongs to the Section Electrocatalysis)

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17 pages, 4486 KB

Open AccessArticle

Tunable Zn-Doping Enhanced Fenton-like Reaction for Butyl Xanthate Degradation: Unveiling the Non-Radical Reaction Pathway

by Shaomeng Huang, Yiqing Xu, Feijian Jing, Liping Wang, Jiawen Sheng and Qiongqiong He

Catalysts 2026, 16(5), 460; https://doi.org/10.3390/catal16050460 - 14 May 2026

Viewed by 464

Abstract

In the process of pollutant degradation by activating peroxymonosulfate (PMS) with carbon-based Fenton-like catalysts containing Fe as the active site, the influence of Zn atoms on the system has rarely been studied. In this study, by regulating the introduction of Zn sources, Fe-Zn-C [...] Read more.

In the process of pollutant degradation by activating peroxymonosulfate (PMS) with carbon-based Fenton-like catalysts containing Fe as the active site, the influence of Zn atoms on the system has rarely been studied. In this study, by regulating the introduction of Zn sources, Fe-Zn-C and Fe-C catalysts were successfully synthesized for activating PMS to degrade butyl xanthate (BX). The degradation experiment results showed that compared to the Fe-C system, the doping of Zn increased the degradation rate of BX in the Fe-Zn-C system by 10.66%, reaching 91.19% within 120 min. Moreover, by optimizing the reaction conditions, the highest BX degradation efficiency of 96.54% was achieved within 30 min. Through instrumental analysis, Fe and Zn elements were found to exist on the surface of the catalysts in the form of Fe²⁺Fe³⁺₂O₄ and ZnO crystals, and the catalytic oxidation reaction was dominated by non-free radical pathways, including ¹O₂ and direct electron transfer pathways. No free radicals were produced during the reaction, and it was speculated that Zn atoms played the role of an electron bridge in the reaction system, mediating electron transfer and enhancing catalytic performance through their synergistic effect with Fe. Comprehensive stability evaluation indicated that Fe-Zn-C ensures continuous catalytic activity and ecological safety with a low dissolution rate in aqueous solution. This study provides a new approach for the design of Fenton-like catalysts and the induction of non-radical pathways. Full article

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14 pages, 7670 KB

Open AccessFeature PaperArticle

Direct Vapour–Solid Synthesis of Intermetallic Pt-Zn and Pt-Te Nanoparticles on Carbon: Enhanced Oxygen Reduction Through Te and Zn Incorporation

by Daniel Garstenauer, Lukas Sallfeldner, Ondřej Zobač, Franz Jirsa and Klaus W. Richter

Catalysts 2026, 16(5), 459; https://doi.org/10.3390/catal16050459 - 14 May 2026

Viewed by 559

Abstract

Intermetallic compounds represent a highly promising class of materials for catalytic applications due to their tuneable structure, composition, and electronic properties. In this study, we report a series of carbon black-supported intermetallic Pt-Te and Pt-Zn nanoparticles synthesized via a novel and facile direct [...] Read more.

Intermetallic compounds represent a highly promising class of materials for catalytic applications due to their tuneable structure, composition, and electronic properties. In this study, we report a series of carbon black-supported intermetallic Pt-Te and Pt-Zn nanoparticles synthesized via a novel and facile direct vapour–solid approach. Their catalytic performance toward the oxygen reduction reaction (ORR) in alkaline media was systematically investigated. Incorporation of Te or Zn into Pt/C significantly enhanced the intrinsic activity, as reflected by an increase in the limiting current density from −2.11 mA cm⁻² for Pt/C to up to −2.94 mA cm⁻² for Pt-Zn and −2.85 mA cm⁻² for Pt-Te systems, while maintaining similar half-wave potentials of 0.79 V vs. RHE and onset potentials around 0.90 V vs. RHE. This work provides a direct comparison of two intermetallic systems prepared under identical conditions, demonstrating how composition and crystal structure determine the catalytic activity and selectivity in the ORR. Full article

(This article belongs to the Special Issue Advances in Electrocatalytic Materials for Hydrogen Energy Technologies)

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17 pages, 5535 KB

Open AccessArticle

CO₂ Reduction in Structured Ni/Mayenite Catalytic System: A Methanation Test by Means of a Pre-Industrial Scaled Chemical Pilot Plant

by Giacomo Seccacini, Martina Fattobene, Leonardo Suraniti, Paola Russo and Mario Berrettoni

Catalysts 2026, 16(5), 458; https://doi.org/10.3390/catal16050458 - 13 May 2026

Viewed by 414

Abstract

The performance of a Mayenite-supported nickel-based catalyst were investigated by using an in-house-designed, assembled and set-up chemical pilot plant, which was developed to provide experimental insights relevant to industrial scale up. In particular, the proposed heterogeneous catalytic system was structured in mm-sized spheres [...] Read more.

The performance of a Mayenite-supported nickel-based catalyst were investigated by using an in-house-designed, assembled and set-up chemical pilot plant, which was developed to provide experimental insights relevant to industrial scale up. In particular, the proposed heterogeneous catalytic system was structured in mm-sized spheres and tested in a large-scale experiment, in a fixed-bed reactor for the CO₂ methanation process, and the results were compared with the output achieved with a Ni/alumina catalyst produced by an analogous route as the benchmark. The obtained findings highlighted the effective potential of the Mayenite structure supporting metallic active sites in promoting CO₂ reduction under the selected operating conditions (450 °C, 4 bar), along with long-term stability and high CH₄ selectivity. Moreover, the available experimental equipment was optimized to achieve accurate estimations of amounts of reaction by-product, as confirmed by the optimal agreement with the mass balance retrieved from the measured gaseous outlet composition. Such an achievement, notable for a large-scale chemical plant, plays a capital role in terms of industrial applications due to the critical impact of residual carbon and water in establishing the viability of innovative catalyst systems for the CO₂ recycling process. Full article

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Catalysts, Volume 16, Issue 5 (May 2026) – 117 articles

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