Catalysts

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

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

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 PaperArticle

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

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 AccessArticle

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

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

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

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

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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16 pages, 1105 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

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

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

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, 7441 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

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)

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

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

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

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 AccessArticle

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

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

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, 1022 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

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)

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

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, 1375 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

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

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

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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