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Volume 16
Issue 4
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Catalysts, Volume 16, Issue 4 (April 2026) – 84 articles

Cover Story (view full-size image): Methane is an abundant and relatively clean resource. Recently, there has been growing interest in methane direct conversion technologies that consume less energy, and among these, research on the direct conversion of methane to acetic acid has made significant progress. This review classifies relevant reports on the direct conversion of methane to acetic acid according to catalyst type (homogeneous vs. heterogeneous catalysts) and reaction conditions, and discusses the advantages and disadvantages of each approach. Recent developments in the field of electrocatalysis for this purpose are noteworthy. Other non-thermal catalytic methods, including photocatalysis, photoelectrocatalysis, and plasma processes, are also included. Based on the latest research trends in this field, future research directions are proposed. View this paper
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17 pages, 1780 KB  
Article
Polyaniline-Encapsulated Cu-NA-MOFs: Facile Synthesis and Dual-Role Electrocatalytic Activity
by Hussain S. AlShahrani, Hadi M. Marwani, Khalid A. Alzahrani, Kahkashan Anjum and Anish Khan
Catalysts 2026, 16(4), 370; https://doi.org/10.3390/catal16040370 - 21 Apr 2026
Viewed by 643
Abstract
The world’s growing need for energy, fueled by industrial expansion and a rising population, continues to be a challenge for the scientific community. The heavy reliance on fossil fuels that contribute to environmental degradation and public health concerns, is shifting toward sustainable alternatives, [...] Read more.
The world’s growing need for energy, fueled by industrial expansion and a rising population, continues to be a challenge for the scientific community. The heavy reliance on fossil fuels that contribute to environmental degradation and public health concerns, is shifting toward sustainable alternatives, with hydrogen production via advanced catalysts as an energy source emerging as a promising solution. This transition addresses the challenges posed by harmful combustion emissions. In this study, we developed an innovative PANI@Cu-NA-MOF nanocomposite catalyst through a sol–gel synthesis approach that strategically integrates conducting polymers with metal–organic frameworks. The catalyst was characterized using different sets of techniques. Surface morphology and elemental composition were investigated using SEM-EDX, while structural analysis was carried out with FTIR that helped to identify the chemical bonds and functional groups, and UV-Vis spectroscopy provided information on its light absorption properties. In addition, TGA was used to evaluate thermal behavior, and XPS offered detailed surface chemical analysis. It was observed by morphology that PANI@Cu-NA-MOF is a noncapsular-like structure. It is thermally highly stable; a TGA study showed that up to 550 °C, almost 2.5% of weight was lost. The single peak in UV-Vis is the preparation of a successful composite. XPS and FTIR reveal the required peaks of functional groups and elements. The PANI@Cu-NA-MOF composite turned out to be quite effective for water electrolysis, requiring an overpotential of just 0.47 V to drive the reaction. When tested against the reversible hydrogen electrode, we observed onset potentials of 1.6 V/RHE for the oxygen evolution reaction and 0.2 V/RHE for the hydrogen evolution reaction. What makes this particularly interesting is that such performance significantly cuts down on the energy needed for electrolysis, which could make hydrogen production much more practical. Since hydrogen burns cleanly and offers a real alternative to fossil fuels, having an efficient catalyst like this brings us one step closer to sustainable energy. Full article
(This article belongs to the Topic Advances in Hydrogen Energy)
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16 pages, 2098 KB  
Article
Spectrally Resolved Cell Imaging for Enhanced Production of ε-Caprolactone via an Enzyme Cascade Reaction in E. coli Immobilized Within Barium–Calcium Alginate Beads Using JetCutter
by Marietta Hakarová, Marek Bučko, Štefánia Hrončeková, Alica Vikartovská, Dušan Chorvát, Anton Mateašik, Pavla Hájovská and Peter Gemeiner
Catalysts 2026, 16(4), 369; https://doi.org/10.3390/catal16040369 - 21 Apr 2026
Viewed by 629
Abstract
Jet-cutting—the most powerful immobilization technique—was utilized for the entrapment of recombinant E. coli cells expressing a cascade of enzymes, including alcohol dehydrogenase, enoate reductase, and cyclohexanone monooxygenase, within mechanically reinforced barium–calcium alginate beads. Cost-effective alginate beads with entrapped cells were applied in a [...] Read more.
Jet-cutting—the most powerful immobilization technique—was utilized for the entrapment of recombinant E. coli cells expressing a cascade of enzymes, including alcohol dehydrogenase, enoate reductase, and cyclohexanone monooxygenase, within mechanically reinforced barium–calcium alginate beads. Cost-effective alginate beads with entrapped cells were applied in a model process for the production of the industrially relevant ε-caprolactone under bioreactor-controlled conditions, enabling parallel repeated biotransformations. Immobilization resulted in a reduced rate of cell deactivation over four biotransformation cycles, leading to overall ε-caprolactone yield increases of 36% using 0.55 mm beads and 22% using 0.9 mm beads compared to the use of free cells. Additionally, the model bioprocess was employed to investigate the metabolic adaptation of cells to immobilization and repeated biotransformations using viability assays and spectrally resolved confocal microscopy. These measurements, conducted for the first time throughout the entire cellular life cycle, clearly demonstrated that the cells retained high viability during cultivation, immobilization, and repeated use in biotransformations. Moreover, based on characteristic spectral shifts, advanced analysis via spectrally resolved confocal microscopy revealed distinct mechanisms of metabolic adaptation in entrapped cells versus free cells during repeated cascade reactions in parallel bioreactors. Full article
(This article belongs to the Special Issue State-of-the-Art Enzyme Engineering and Biocatalysis in Europe)
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19 pages, 2328 KB  
Article
Precisely Engineered Nitrogen-Doped Hierarchical Porous Carbon from Lignin for High-Rate and Ultra-Stable Supercapacitors
by Zhebiao Xu, Siyu Song, Zhuangjia Chen, Wenzhuo Wang, Yushen Huang, Fudong Bai, Riyang Shu, Zhipeng Tian and Chao Wang
Catalysts 2026, 16(4), 368; https://doi.org/10.3390/catal16040368 - 20 Apr 2026
Viewed by 648
Abstract
The development of high-performance and sustainable carbon electrodes is increasingly important for next-generation supercapacitors, yet controlling heteroatom doping and hierarchical pore evolution in biomass-derived carbons remains a key challenge. Lignin, as an abundant aromatic biopolymer, offers a structurally rich platform for designing functional [...] Read more.
The development of high-performance and sustainable carbon electrodes is increasingly important for next-generation supercapacitors, yet controlling heteroatom doping and hierarchical pore evolution in biomass-derived carbons remains a key challenge. Lignin, as an abundant aromatic biopolymer, offers a structurally rich platform for designing functional carbons, but its rigid cross-linked architecture limits precise pore regulation and efficient nitrogen incorporation. In this work, nitrogen-doped hierarchical porous carbons were engineered from enzymatically treated lignin through a synergistic urea-assisted nitrogen doping and KOH activation strategy. The urea–KOH co-activation drives the coordinated evolution of micropores and mesopores. This approach yields an optimized carbon material possessing a high BET surface area of 2569 m2 g−1, an interconnected micro–mesoporous architecture, and a favorable distribution of pyridinic, pyrrolic, and graphitic nitrogen species. The engineered pore hierarchy is correlated with enhanced ion transport kinetics, as evidenced by a high b value of 0.99 and a capacitive contribution of 98.5% at 100 mV s−1; nitrogen functionalities introduce redox-active sites and improve interfacial wettability. As a result, the selected material delivers a high specific capacitance of 221 F g−1 at 0.5 A g−1, strong rate capability with 84.4% retention at 20 A g−1, and excellent cycling durability with 90.7% capacitance retention after 50,000 cycles. This study demonstrates a potentially mechanistically informed, scalable pathway for coupling enzymatic structural regulation with chemical activation, offering a sustainable route for transforming lignin into high-value carbon electrodes suitable for advanced supercapacitor applications. Full article
(This article belongs to the Special Issue Catalysis for Solid Waste Upcycling: Challenges and Opportunities)
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35 pages, 2003 KB  
Review
Nano–Bio Hybrid Catalysts: Enzyme–Nanomaterial Interfaces for Sustainable Energy Conversion
by Ghazala Muteeb, Youssef Basem, Abdel Rahman Alaa, Mahmoud Hassan Ismail, Mohammad Aatif, Mohd Farhan, Sheeba Kumari and Doaa S. R. Khafaga
Catalysts 2026, 16(4), 367; https://doi.org/10.3390/catal16040367 - 19 Apr 2026
Cited by 1 | Viewed by 1126
Abstract
Nano–bio hybrid catalysts have emerged as a promising platform for sustainable energy conversion by integrating the high selectivity of enzymes with the structural robustness and conductivity of nanomaterials. In recent years, the growing demand for clean energy technologies has driven the development of [...] Read more.
Nano–bio hybrid catalysts have emerged as a promising platform for sustainable energy conversion by integrating the high selectivity of enzymes with the structural robustness and conductivity of nanomaterials. In recent years, the growing demand for clean energy technologies has driven the development of biohybrid systems capable of efficient electron transfer, enhanced catalytic activity, and improved operational stability. This review comprehensively discusses the design principles, mechanistic foundations, and performance metrics of enzyme–nanomaterial interfaces for energy-related applications. We first outline the fundamentals of enzymatic redox catalysis and the limitations of free enzymes in practical systems. Subsequently, we examine the functional roles of nanomaterials including carbon-based materials, metal and metal oxide nanoparticles, and two-dimensional platforms such as MXenes in facilitating enzyme immobilization and promoting direct or mediated electron transfer. Special emphasis is placed on engineering strategies at the bio–nano interface, including immobilization techniques, surface functionalization, and structural tuning to optimize catalytic efficiency. The review further highlights representative hybrid systems based on laccase, glucose oxidase, peroxidase, and hydrogenase enzymes, and evaluates their applications in biofuel cells, solar–bio hybrid systems, green oxidation reactions, and self-powered biosystems. Stability challenges, deactivation mechanisms, and enhancement strategies such as polymer coatings, cross-linking, and nanoconfinement are critically analyzed. Finally, emerging directions including artificial enzymes, AI-guided catalyst design, and self-healing bioelectrodes are discussed to provide a forward-looking perspective on next-generation sustainable bioelectrocatalytic systems. Full article
(This article belongs to the Special Issue Advanced Catalysis for Energy and a Sustainable Environment)
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32 pages, 18305 KB  
Review
Advances in Thermochemical/Catalytic Conversion Technologies for Co-Processing of Biomass and Municipal Solid Wastes
by Yujian Wu, Wenwen Liu, Linhong Xie, Leihe Cai, Haowei Li, Shengxian Xian, Zheng Liang, Qing Xu and Chunbao Xu
Catalysts 2026, 16(4), 366; https://doi.org/10.3390/catal16040366 - 18 Apr 2026
Viewed by 1483
Abstract
Thermochemical/catalytic co-processing of biomass and solid wastes is a promising route for waste valorization, low-carbon energy recovery, and the co-production of fuels, chemicals, and carbon materials. Conventional pathways, including pyrolysis, gasification, liquefaction, and carbonization, provide the basic framework for mixed-feed conversion. Emerging routes, [...] Read more.
Thermochemical/catalytic co-processing of biomass and solid wastes is a promising route for waste valorization, low-carbon energy recovery, and the co-production of fuels, chemicals, and carbon materials. Conventional pathways, including pyrolysis, gasification, liquefaction, and carbonization, provide the basic framework for mixed-feed conversion. Emerging routes, such as flash Joule heating, microwave-assisted conversion, plasma processing, supercritical water treatment, solar-driven systems, and machine-learning-assisted optimization, further expand opportunities for process intensification and selective upgrading. Owing to feedstock complementarity, including hydrogen donation from plastics, catalytic effects of ash minerals, and interactions among reactive intermediates, co-processing can enhance deoxygenation, hydrogen generation, aromatization, and carbon utilization. Major challenges remain, however, including feedstock heterogeneity, reactor scale-up, catalyst stability, and the limited transferability of laboratory-scale synergy to realistic waste streams. Future progress should therefore focus on continuous validation, mechanistic clarification, and integrated techno-economic, life-cycle, and data-driven assessments. Full article
(This article belongs to the Special Issue Catalytic Transformation of Biomass: From Waste to Fuels, Chemicals and High-Value Products)
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23 pages, 10512 KB  
Review
Zeolite-Based Heterogeneous Catalysts for Biodiesel Production: Recent Progress in the Valorization of Waste-Derived and Next-Generation Feedstocks
by Shahina Riaz, Ziyauddin S. Qureshi, Muhammad Naseem Akhtar, Essra Altahir, Abdullah H. Albin Saad, Aaron C. Akah, Mohammad A. Alkhunaizi, Rashed M. Aleisa and Omar Y. Abdelaziz
Catalysts 2026, 16(4), 365; https://doi.org/10.3390/catal16040365 - 17 Apr 2026
Viewed by 842
Abstract
Biodiesel is a sustainable and promising alternative energy source produced from renewable raw materials using various methods. One effective approach is simultaneous esterification and transesterification, which relies on suitable catalysts that can be either homogeneous or heterogeneous. Homogeneous catalysts (acid or base) offer [...] Read more.
Biodiesel is a sustainable and promising alternative energy source produced from renewable raw materials using various methods. One effective approach is simultaneous esterification and transesterification, which relies on suitable catalysts that can be either homogeneous or heterogeneous. Homogeneous catalysts (acid or base) offer high activity but are corrosive and difficult to recover, necessitating energy-intensive processes such as aqueous quenching and neutralization, which can lead to soap formation and stable emulsions. By comparison, heterogeneous catalytic systems overcome many of these challenges due to their ease of recovery, reusability, and simplified product separation, which collectively enhance economic viability and environmental sustainability. This review highlights recent progress in the application of zeolite-based solid catalysts for biodiesel synthesis, with particular emphasis on their use in converting waste cooking oil and other low-cost feedstocks, including non-edible oils, non-food biomass sources, algal resources, and genetically engineered microorganisms. Key factors such as catalytic activity, selectivity, catalyst loading, and reusability are discussed, highlighting the advantages of zeolites due to their unique crystal structure, high thermal stability, and ease of product recovery. Overall, this review underscores the challenges and opportunities in zeolite-based catalysis to provide a comprehensive understanding of its potential to enhance the efficiency and scalability of biodiesel production. Full article
(This article belongs to the Special Issue Catalysis for Sustainable Energy: Biodiesel and Biolubricant Innovations)
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14 pages, 1523 KB  
Article
Simultaneous Enhancement of H2 and O2 Permeation in Proton Ceramic Honeycomb-Structured Hollow Fiber Membranes via Fe3+ and Y3+ Co-Doping
by Lihui Wang, Shao Zhang, Mingming Wang, Zhigang Wang and Xiaoyao Tan
Catalysts 2026, 16(4), 364; https://doi.org/10.3390/catal16040364 - 17 Apr 2026
Viewed by 503
Abstract
The high-temperature proton ceramic membranes with simultaneous separation of hydrogen and oxygen exhibit promising applications in the catalytic conversion field. However, their separation performance often relies on external electrical circuits, which limits practical application. To overcome this limitation, doping strategies have emerged as [...] Read more.
The high-temperature proton ceramic membranes with simultaneous separation of hydrogen and oxygen exhibit promising applications in the catalytic conversion field. However, their separation performance often relies on external electrical circuits, which limits practical application. To overcome this limitation, doping strategies have emerged as a viable approach to develop triple-conducting (H+/e−/O2−) membranes for simultaneous hydrogen and oxygen separation in non-electrochemical mode. In this study, honeycomb-structured hollow fiber membranes were fabricated, and the effects of varying Fe3+ and Y3+ doping concentrations on hydrogen and oxygen permeation fluxes were systematically investigated. At the Fe3+ doping level of 0.2 mol, the oxygen permeation flux of 0.692 mL min−1 cm−2 in BaCe0.6Zr0.2Fe0.2O3−δ (BCZF) was achieved at 1000 °C, while the hydrogen permeation flux was 0.201 mL min−1 cm−2. The BaCe0.55 Fe0.05Zr0.2Y0.2O3−δ (Fe-BCZY) hollow fiber membrane can enhance the hydrogen permeation flux by 75% at 1000 °C. Furthermore, during the simultaneous permeation of hydrogen and oxygen, a 1.7-fold enhancement in hydrogen permeation performance was achieved for the Fe-BZCY hollow fiber membrane at 1000 °C, and with oxygen permeation flux of 1.76 mL min−1 cm−2 at the same temperature. More significantly, a hydrogen permeation flux of 0.34 mL min−1 cm−2 can be achieved at 700 °C under simultaneous hydrogen and oxygen permeation, which is favorable for the application of membrane reactors in catalytic reactions. Full article
(This article belongs to the Section Catalytic Reaction Engineering)
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17 pages, 4144 KB  
Article
Sonocatalytic Degradation of Malachite Green Using a Sustainable ZnO/Biochar Composite Derived from Phytoremediated Plant Residue: Process Optimisation via Response Surface Methodology
by Jia Wei Tai, Yean Ling Pang, Wei-Hsin Chen, Yi-Kai Chih, Steven Lim and Woon Chan Chong
Catalysts 2026, 16(4), 363; https://doi.org/10.3390/catal16040363 - 17 Apr 2026
Viewed by 556
Abstract
A highly efficient ZnO/biochar (ZnO/BC) composite was synthesised from phytoremediation residue and evaluated for the advanced sonocatalytic degradation of malachite green in aqueous solutions. The structural, chemical, and morphological properties of the composite were characterised using physicochemical techniques, confirming the successful impregnation of [...] Read more.
A highly efficient ZnO/biochar (ZnO/BC) composite was synthesised from phytoremediation residue and evaluated for the advanced sonocatalytic degradation of malachite green in aqueous solutions. The structural, chemical, and morphological properties of the composite were characterised using physicochemical techniques, confirming the successful impregnation of zinc oxide (ZnO) onto the biochar matrix. The catalytic performance of the synthesised composite in treating malachite green was systematically evaluated and optimised using response surface methodology (RSM), specifically a central composite design (CCD), to analyse the interactive effects of initial dye concentration, catalyst loading, and ultrasonic irradiation time. The developed model exhibited a high coefficient of determination (R2) of 0.996 and an adequate precision of 62.67, confirming the model’s significance. Optimal degradation was observed at an initial malachite green concentration of 73.71 mg/L, a catalyst loading of 0.527 g/L, and a sonocatalytic treatment duration of 18.7 min. Furthermore, the ZnO/biochar composite demonstrated excellent mineralisation capabilities, with chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies reaching 89.79% and 68.43%, respectively, after 60 min of treatment. These findings establish ZnO/BC as a highly active sonocatalyst, offering a promising approach for the remediation of organic dyes in industrial wastewater treatment. Full article
(This article belongs to the Special Issue Microporous and Mesoporous Materials for Catalytic Applications, 2nd Edition)
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17 pages, 3743 KB  
Article
Tailoring Al2O3-Cl for n-Butane Isomerization: Unraveling the Impact of Precursor Synthesis on Support Architecture and Acidity
by Xiong Peng, Zhongwei Yu, Yongfen Zhang, Hongquan Liu, Yanpeng Yang, Jinzhi Li and Aizeng Ma
Catalysts 2026, 16(4), 362; https://doi.org/10.3390/catal16040362 - 17 Apr 2026
Viewed by 585
Abstract
The rational design of supported Lewis acid catalysts is frequently impeded by an incomplete understanding of how the support’s synthetic history governs its intrinsic acidity and catalytic efficacy. Herein, we elucidate the structure–property–performance relationship linking the aging dynamics of a boehmite precursor to [...] Read more.
The rational design of supported Lewis acid catalysts is frequently impeded by an incomplete understanding of how the support’s synthetic history governs its intrinsic acidity and catalytic efficacy. Herein, we elucidate the structure–property–performance relationship linking the aging dynamics of a boehmite precursor to the activity of the resultant chlorinated alumina (Al2O3–Cl) catalyst in n-butane isomerization. Using n-butane as the probe feedstock, we investigated how alumina supports with distinct physicochemical properties regulate the performance of Al2O3–Cl catalysts for n-butane isomerization. By systematically adjusting the aging parameters (stirring rate, temperature, and time), we reveal that the structural evolution of the alumina support transitions from initial particle aggregation to Ostwald ripening and surface reconstruction. A decisive structure–performance correlation is identified: precursor synthesis conditions govern both the population and accessibility of specific surface hydroxyls (notably Type II terminal OH groups), which act as anchoring sites for the generation of active Lewis acid centers upon chlorination. Optimal aging parameters (300 rpm, 90 °C, 6 h) promote the formation of a hierarchical pore architecture with a maximized density of accessible hydroxyls, thereby affording enhanced Lewis acidity and superior isomerization activity. This work provides a fundamental framework for tailoring solid acid catalysts by precisely engineering the precursor architecture. Full article
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17 pages, 3983 KB  
Article
Sustainable Methanolysis of PLA Enabled by a Biochar-Supported Catalyst: Toward PET Purification in Mixed Polymer Waste
by Felice Kubale, Herman A. Murillo, Alexis Debut and Sebastian Ponce
Catalysts 2026, 16(4), 361; https://doi.org/10.3390/catal16040361 - 17 Apr 2026
Viewed by 584
Abstract
The development of selective and sustainable catalysts is essential to enable the chemical recycling of mixed plastic waste. In this work, calcium-modified biochars derived from cocoa pod husk (CPH) and palm kernel shell (PKS) were prepared for treating a mixture of poly(ethylene terephthalate) [...] Read more.
The development of selective and sustainable catalysts is essential to enable the chemical recycling of mixed plastic waste. In this work, calcium-modified biochars derived from cocoa pod husk (CPH) and palm kernel shell (PKS) were prepared for treating a mixture of poly(ethylene terephthalate) (PET) and poly(lactic acid) (PLA). The aim was to separate the mixture through the PLA methanolysis, while maintaining the PET unreacted for a potential physical recycling. Biochar was ex situ modified with calcium precursor using a value-added concentrate recovered from the hydrothermal treatment of Jatropha fruit husk. Subsequently, a pyrolysis step was further applied to convert the calcium species into CaO, which is the active phase for the methanolysis reaction. Structural, microscopic, and spectroscopic analyses revealed that the carbon matrix strongly influences the evolution and stabilization of calcium phases during pyrolysis and post-treatment. CPH-derived biochars promoted the formation of highly dispersed CaO, whereas PKS favored the growth of larger, less reactive Ca(OH)2 domains. As a result, the CPH_Ca10 (i.e., 10% desired calcium loading based on CPH-biochar mass) catalyst exhibited superior basicity and catalytic activity, achieving near-complete PLA conversion under mild conditions (90–110 °C) depending on the system with only 2 wt.% catalyst. Importantly, under these mild conditions, PET remained chemically intact, demonstrating the process’s high selectivity and applicability to mixed bioplastic–fossil plastic streams. This study highlights a circular, low-carbon route to producing effective Ca-based catalysts from agricultural residues. It establishes a promising strategy for selective depolymerization and separation in complex plastic waste systems. Full article
(This article belongs to the Special Issue 15th Anniversary of Catalysts: Recent Advances in Environmental Catalysis)
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21 pages, 2722 KB  
Article
Polyphenols Extracted from Grape Pomace as Synthesis Directing Agents of Photoactive ZnO: A Morphology and Reactivity Study
by Mattia Di Maro, Giuliana Magnacca, Alessandra Bianco Prevot, Mery Malandrino, Carlo Ferrero, Luciana Baggi, Enzo Laurenti, Sara Venturi, Davide Palma, Giorgio Grillo, Silvia Tabasso, Maria Giulia Faga, Massimo Guaita, Silvia Motta, Antonella Bosso and Giovanna Gautier di Confiengo
Catalysts 2026, 16(4), 360; https://doi.org/10.3390/catal16040360 - 16 Apr 2026
Viewed by 663
Abstract
ZnO can be easily obtained using different salts as precursors, and many examples are present in the literature describing the effect of several additives in the synthesis. In this paper, we study the effects of the addition of polyphenols present in the residues [...] Read more.
ZnO can be easily obtained using different salts as precursors, and many examples are present in the literature describing the effect of several additives in the synthesis. In this paper, we study the effects of the addition of polyphenols present in the residues of the wine supply chain. The polyphenols are extracted from grape pomace and fractionated, exploiting a membrane-based process equipped with polysulfone ultrafiltration membranes (cut-off 1 kDa and 5 kDa) that can separate the plethora of molecules into larger than 5 kDa and smaller than 1 kDa. The extract and its fractions after the ultrafiltration process were used as additives for the thermal precipitation synthesis of ZnO from Zn acetate. The chemical and physical properties were studied with the aim of understanding the characteristics that influence the activity of the photocatalysts. To this purpose, a commercial system was used for comparison, and the photoactivity was analyzed with a caffeine solution upon irradiation, exploiting the UVA and VIS electromagnetic radiation for the activation of the catalytic materials. The kind of polyphenol fraction affects the surface behaviors of the nanoparticles. Morphology, presence of trapped hole/electron centers, and acidity/basicity of the surface sites of ZnO appear to be the most relevant features in the efficiency towards caffeine degradation. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation, 2nd Edition)
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24 pages, 2664 KB  
Article
Mechanism-Guided Selective Hydrogenation of CO2 to Light Olefins: DFT-Informed Microkinetics and Surface Electronic Regulation Under Green Hydrogen Scenarios
by Han Song, Maoyuan Yin, Xiaohan Zhang, Xiaoli Rong, Zheng Li and Hailing Ma
Catalysts 2026, 16(4), 359; https://doi.org/10.3390/catal16040359 - 16 Apr 2026
Viewed by 506
Abstract
Achieving high selectivity in the hydrogenation of CO2 to light olefins remains challenging because of the complex reaction network and the difficulty of regulating key intermediates. Motivated by green-hydrogen-enabled power-to-chemicals pathways, we combine density functional theory (DFT) with first-principles microkinetic simulation (FPMS) [...] Read more.
Achieving high selectivity in the hydrogenation of CO2 to light olefins remains challenging because of the complex reaction network and the difficulty of regulating key intermediates. Motivated by green-hydrogen-enabled power-to-chemicals pathways, we combine density functional theory (DFT) with first-principles microkinetic simulation (FPMS) to construct a quantitatively predictive reaction-energy landscape and elucidate structure–selectivity relationships. A comprehensive reaction network is established through energy-surface fitting, and steady-state rate constants are solved to capture the microkinetic competition between elementary steps. By introducing electronic density-of-states (DOS) modulation as a design variable, we directly correlate surface structural parameters with rate-controlling steps, thereby enabling targeted regulation of C–C coupling and hydrogen transfer processes. The calculated barrier for CO2 adsorption to COOH* is 1.35 eV, while the transition state barrier for C–C coupling is 1.50 eV, corresponding to a reaction rate of 9.7 × 103 s−1; the olefin desorption rate reaches 1.7 × 107 s−1. Crucially, shifting the d-band center from −2.35 eV to −1.60 eV increases the C2–C4 olefin selectivity from 42.6% to 68.3%, establishing an actionable electronic structure lever for catalyst optimization. These results reveal the intrinsic mechanism by which surface electronic and geometric regulation governs intermediate stabilization and rate control, providing a verifiable, mechanism-based design principle for efficient CO2-to-olefin catalysts aligned with green hydrogen deployment. Full article
(This article belongs to the Special Issue Electrochemical Catalysis of Two-Dimensional Layered Materials for Energy Conversion and Storage)
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17 pages, 6098 KB  
Article
Electric-Field-Driven Tourmaline/BiOCl Visible-Light Photocatalysis for Efficient Removal of Ofloxacin
by Xiangwei Tang, Yuanbiao Bai, Tianyu Liu, Lianyao Tang, Peiming Peng, Yiting Bu, Wan Shao, Haoqiang Zhang, Yaocheng Deng and Dong Liu
Catalysts 2026, 16(4), 358; https://doi.org/10.3390/catal16040358 - 16 Apr 2026
Viewed by 540
Abstract
Bismuth oxychloride (BiOCl) has garnered significant research interest owing to its non-toxicity, affordability, and distinct layered structure. Although BiOCl possesses promising photocatalytic potential, its large band gap and rapid photocarrier recombination restrict its practical use. In this work, a natural tourmaline mineral was [...] Read more.
Bismuth oxychloride (BiOCl) has garnered significant research interest owing to its non-toxicity, affordability, and distinct layered structure. Although BiOCl possesses promising photocatalytic potential, its large band gap and rapid photocarrier recombination restrict its practical use. In this work, a natural tourmaline mineral was effectively integrated with BiOCl to form a composite (TBO). Comprehensive characterization and photocatalytic assessments revealed that the intrinsic electric field of tourmaline notably strengthened both the adsorption capacity and the light-driven catalytic efficiency of BiOCl. Under visible-light irradiation, ofloxacin (OFX, 10 ppm) was eliminated by approximately 98% within 60 min. The apparent reaction rate constant (k) of TBO was 0.0407 min−1, which was approximately 184.8 and 2.26 times those of tourmaline alone and pristine BiOCl, respectively. Furthermore, both the visible-light absorption and the separation efficiency of photogenerated electron–hole pairs were significantly enhanced. After evaluating its behavior under various simulated natural environmental conditions, TBO displayed strong potential for practical application. Reactive species trapping and analysis identified singlet oxygen (1O2) and superoxide radicals (·O2−) as the primary active species in photocatalysis. Moreover, the degradation route of ofloxacin and the toxicity of its intermediates were systematically examined. These findings offer meaningful guidance for improving photocatalytic materials by utilizing naturally occurring minerals. Full article
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26 pages, 5537 KB  
Article
Ni/MgO-Al2O3 Hydrotalcite-Derived Catalysts for Sustainable Iso-Butanol Generation from Methanol/Ethanol Blends
by Joachim Pasel, Justus Hüging, Quoc Khanh Tran and Ralf Peters
Catalysts 2026, 16(4), 357; https://doi.org/10.3390/catal16040357 - 16 Apr 2026
Viewed by 733
Abstract
The catalytically supported upgrading of green ethanol and green methanol mixtures can produce higher alcohols, such as iso-butanol, in a sustainable manner. Iso-butanol can be used as a feedstock to defossilize the chemical and transportation sectors. MgO-Al2O3 hydrotalcite-based catalysts are [...] Read more.
The catalytically supported upgrading of green ethanol and green methanol mixtures can produce higher alcohols, such as iso-butanol, in a sustainable manner. Iso-butanol can be used as a feedstock to defossilize the chemical and transportation sectors. MgO-Al2O3 hydrotalcite-based catalysts are a promising option for this purpose. In this paper, samples were synthesized using co-precipitation and urea methods with different Mg/Al molar ratios with Ni acting as the active catalytic component. Thereby, the catalysts synthesized using the urea method exhibited the greatest activity, producing iso-butanol concentrations of up to 170 mmol L−1 at 185 °C, with selectivities towards iso-butanol of 85–89% and a maximum space–time yield of 8.2 mmol g−1 h−1. The most active catalyst among all samples from this paper was characterized by 100% proportions of strong basic and medium acidic catalyst sites and the largest specific surface area. XRD analysis revealed the presence of NiO, MgO and the spinels Al2NiO4 and Al2MgO4 in both synthesis variants as well as elemental Ni in one sample from the urea synthesis. CO2-TPD and NH3-TPD experiments showed the dominance of strong basic and medium/strong acidic catalyst sites in both synthesis pathways. Full article
(This article belongs to the Section Catalysis for Sustainable Energy)
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23 pages, 3738 KB  
Review
Research Progress on Novel Semiconductor Photocatalysts for Degrading VOCs
by Xiu-Juan Feng, Xin Shi, Hao-Yu Zhang, Chu-Hao Huang and Qing-Bo Yu
Catalysts 2026, 16(4), 356; https://doi.org/10.3390/catal16040356 - 15 Apr 2026
Viewed by 794
Abstract
Volatile organic compounds (VOCs) pose significant health risks. Photocatalytic oxidation offers a promising route for VOC purification under ambient conditions. Based on a review of over 80 studies, this article critically evaluates research progress on four semiconductor photocatalyst systems (TiO2-based, g-C [...] Read more.
Volatile organic compounds (VOCs) pose significant health risks. Photocatalytic oxidation offers a promising route for VOC purification under ambient conditions. Based on a review of over 80 studies, this article critically evaluates research progress on four semiconductor photocatalyst systems (TiO2-based, g-C3N4-based, bismuth-based oxides, and MOFs) for VOC degradation. Unlike traditional descriptive reviews, this work establishes a quality-based filtering framework to distinguish studies reporting standardized photochemical parameters from those that do not. The analysis reveals a fundamental problem: the vast majority of reviewed studies lack essential parameters (incident photon flux, apparent quantum yield, or rigorous dark adsorption equilibrium), rendering cross-study comparisons invalid. Most literature relies on non-standardized metrics such as conversion percentages or rate constants per catalyst mass. While some high-quality studies report AQY, these remain a small fraction of the literature. Within individual studies under identical conditions, modification strategies enhance activity relative to controls, but relative efficiency (ζr) values are meaningful only within the same study and cannot be compared across setups. This review thus serves a dual purpose: to summarize modification strategies and to critically expose the lack of standardization. Future research must adopt unified reporting standards (photon flux, AQY, benchmarks under identical conditions) to transform the field into a reproducible, cumulative science. Full article
(This article belongs to the Special Issue Advanced Photocatalytic Technologies for Sustainable Environmental Treatment)
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41 pages, 4060 KB  
Review
Reimagining Textile Effluent Treatment Using Metal–Organic Framework-Based Hybrid Catalysts: A Critical Review
by Hossam A. Nabwey and Maha A. Tony
Catalysts 2026, 16(4), 355; https://doi.org/10.3390/catal16040355 - 15 Apr 2026
Viewed by 1239
Abstract
Textile wastewater remains one of the most challenging industrial effluents to remediate due to its intense and persistent coloration, high organic load, elevated salinity, and fluctuating pH and the presence of recalcitrant dye structures and auxiliary chemicals. Conventional physicochemical and biological treatments frequently [...] Read more.
Textile wastewater remains one of the most challenging industrial effluents to remediate due to its intense and persistent coloration, high organic load, elevated salinity, and fluctuating pH and the presence of recalcitrant dye structures and auxiliary chemicals. Conventional physicochemical and biological treatments frequently achieve incomplete removal, generate secondary wastes, or fail under high-salt and toxic dye matrices. Advanced oxidation processes (AOPs) provide molecular-level degradation via reactive oxygen species (ROS), yet their deployment is often constrained by narrow operating windows, catalyst instability, chemical/energy demand, and scale-up limitations. In this context, metal–organic frameworks (MOFs) have emerged as tunable porous catalytic platforms that integrate adsorption and oxidation within a single architecture through controllable metal nodes, functional linkers, and engineered pore environments. This critical review reimagines textile effluent treatment through the lens of MOF-based hybrid catalysts, synthesizing progress across Fenton/photo-Fenton catalysis, photocatalytic MOFs, persulfate activation, and MOF-derived/composite systems. Mechanistic pathways are discussed by linking pollutant enrichment, cyclic redox reactions, charge-transfer processes, and ROS-driven degradation toward mineralization, with emphasis on the distinction between rapid decolorization and true organic removal. A critical comparison highlights how hybridization improves charge transport, stability, and catalyst recovery, while persistent gaps remain in hydrolytic robustness, metal leaching control, intermediate toxicity assessment, real-wastewater validation, continuous-flow reactor integration, and techno-economic feasibility. Finally, the review outlines actionable research directions, including water-stable and defect-engineered MOFs, immobilized and structured catalysts, solar-driven operation, standardized performance metrics, and life-cycle-informed design, to accelerate translation toward scalable and sustainable textile wastewater remediation. By bridging material chemistry with reactor-level feasibility and sustainability assessment, this review provides an implementation-oriented perspective for next-generation textile wastewater treatment. Full article
(This article belongs to the Special Issue Metal–Organic Framework Catalysts: Celebrating a Nobel Prize and Forging Future Developments and Applications)
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19 pages, 8771 KB  
Article
High-Entropy NiCoZnVCrOx Oxides Serve as Oxygen Carriers for NO Reduction
by Weiwei Cai and Min Zheng
Catalysts 2026, 16(4), 354; https://doi.org/10.3390/catal16040354 - 15 Apr 2026
Viewed by 539
Abstract
Flue gas denitrification represents an environmentally friendly and economically viable strategy for alleviating energy crises and advancing carbon neutrality goals. Although traditional selective catalytic reduction (SCR) catalysts demonstrate excellent denitrification efficiency and catalytic stability, they still face significant challenges, including high cost and [...] Read more.
Flue gas denitrification represents an environmentally friendly and economically viable strategy for alleviating energy crises and advancing carbon neutrality goals. Although traditional selective catalytic reduction (SCR) catalysts demonstrate excellent denitrification efficiency and catalytic stability, they still face significant challenges, including high cost and ammonia slip. In this study, the high-entropy oxide (HEO) NiCoZnVCrOx was synthesized via the sol–gel method and evaluated for the reduction of NO to N2. The effects of varying reaction conditions on the NO reduction performance of this material were systematically investigated alongside the underlying reaction mechanism. The results reveal that the reduced oxygen carrier (OC) achieves optimal performance at an oxidation temperature of 800 °C, oxidizing gas flow rate of 200 mL/min and reduction time of 60 min, yielding the highest NO conversion and N2 selectivity while simultaneously minimizing NO2 selectivity. The reaction mechanism was further elucidated through a series of characterization techniques, including DRIFTS. Overall, this HEO demonstrates significant potential as a candidate OC for flue gas denitrification. Full article
(This article belongs to the Special Issue Advanced Catalytic Technologies for NOx Abatement and Environmental Sustainability)
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24 pages, 817 KB  
Review
Catalytic Systems and Mechanistic Insights into Crotonaldehyde Synthesis from Acetaldehyde: A Comprehensive Review
by Kai Yang, Feng Shi and Lingtao Wang
Catalysts 2026, 16(4), 353; https://doi.org/10.3390/catal16040353 - 15 Apr 2026
Viewed by 1247
Abstract
This paper systematically reviews the recent advances in catalytic systems and reaction mechanisms for the synthesis of crotonaldehyde via aldol condensation using acetaldehyde as the feedstock. Firstly, the structural characteristics, reactivity, and important applications of crotonaldehyde in fine chemicals are outlined, with particular [...] Read more.
This paper systematically reviews the recent advances in catalytic systems and reaction mechanisms for the synthesis of crotonaldehyde via aldol condensation using acetaldehyde as the feedstock. Firstly, the structural characteristics, reactivity, and important applications of crotonaldehyde in fine chemicals are outlined, with particular emphasis on the limitations of traditional homogeneous base-catalyzed processes, such as difficulty in separation and environmental pollution caused by waste streams. On this basis, heterogeneous catalytic systems are discussed in detail, focusing on the progress of metal oxides, aluminosilicate zeolites, and heteroatom zeolites in regulating acid–base properties, active site structures, and reaction pathways. Furthermore, the typical carbanion mechanism and direct condensation mechanism in aldol condensation are summarized, and the catalyst deactivation and by-product formation mechanisms are analyzed. Finally, perspectives on the construction of efficient and green catalytic systems and future research directions are proposed, aiming to provide theoretical guidance for process optimization and catalyst design in crotonaldehyde synthesis from acetaldehyde. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental and Energy Sustainability)
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24 pages, 3258 KB  
Article
Eco-Friendly Synthesis of Zn-Doped CuO Nanoparticles Using Aloysia citrodora Extract for Highly Efficient Fenton-like Dye Degradation
by Aicha Hazmoune, Chahra Boukaous, Mazen S. F. Al-Hazeef, Mohammed Salah Aida, Farid Fadhillah, Amine Aymen Assadi, Abdeltif Amrane, Fekri Abdulraqeb Ali, Jie Zhang and Hichem Tahraoui
Catalysts 2026, 16(4), 352; https://doi.org/10.3390/catal16040352 - 14 Apr 2026
Viewed by 1128
Abstract
The development of efficient, sustainable, and low-cost catalysts for wastewater treatment remains a major environmental challenge. In this work, Zn-doped CuO nanostructures were successfully synthesized via a green route using Aloysia citrodora leaf extract as a natural reducing and stabilizing agent. The structural [...] Read more.
The development of efficient, sustainable, and low-cost catalysts for wastewater treatment remains a major environmental challenge. In this work, Zn-doped CuO nanostructures were successfully synthesized via a green route using Aloysia citrodora leaf extract as a natural reducing and stabilizing agent. The structural and morphological properties of the prepared catalysts were systematically characterized by XRD, Raman spectroscopy, FTIR, SEM, and EDX analyses. The results revealed the formation of highly crystalline monoclinic CuO nanoparticles, whose defect density and surface properties were significantly modified by Zn incorporation. The catalytic performance of the synthesized materials was evaluated through the heterogeneous Fenton-like degradation of Rhodamine B in aqueous solution under dark conditions. The Zn-doped CuO catalyst exhibited outstanding degradation efficiency (~99.97%) within only 30 min, using a low catalyst dosage of 15 mg and a minimal H2O2 amount of 25 μL. The enhanced catalytic activity is attributed to the synergistic interaction between Zn-induced lattice defects and the Cu2+/Cu+ redox cycle, which promotes efficient H2O2 activation and •OH radical generation. Radical scavenging experiments confirmed the dominant role of hydroxyl radicals in the degradation process. Compared with previously reported CuO-based catalysts, the present system demonstrates superior performance in terms of reaction rate, oxidant consumption, and energy efficiency. These findings highlight the potential of Zn-doped CuO synthesized via green chemistry as a promising and sustainable catalyst for advanced wastewater treatment applications. Full article
(This article belongs to the Special Issue Recent Developments in Photo-/Electrocatalysis: A Themed Issue in Honor of Prof. Trong-On Do)
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18 pages, 3245 KB  
Article
Molecular Dynamics Simulations of Functionalized UiO-66 in Transesterification Reactions
by Dantong Wen, Xiaohong Hao and Jinchuan Wang
Catalysts 2026, 16(4), 351; https://doi.org/10.3390/catal16040351 - 14 Apr 2026
Viewed by 636
Abstract
This study employs molecular dynamics simulations to investigate the influence of functionalized UiO-66 materials (with -H, -NH2, -NO2, and -(OH)2 groups) on the adsorption and diffusion behaviors of ethanol and waste oil before transesterification reactions. A multi-scale modeling [...] Read more.
This study employs molecular dynamics simulations to investigate the influence of functionalized UiO-66 materials (with -H, -NH2, -NO2, and -(OH)2 groups) on the adsorption and diffusion behaviors of ethanol and waste oil before transesterification reactions. A multi-scale modeling approach, including a three-layer interfacial model, surface adsorption, and intra-framework adsorption, was utilized to systematically evaluate the effects of functionalization on structural properties, molecular diffusion, adsorption performance, and interfacial interactions. The simulation results reveal that functionalization enhances the intrinsic diffusivity of the metal–organic framework but generally suppresses the diffusion of ethanol and waste oil. The -(OH)2 group exhibits the most significant diffusion hindrance due to steric effects and strong hydrogen bonding. Adsorption of waste oil is dominated by coordination and hydrophobic interactions, while ethanol adsorption relies on hydrogen bonding. Within the framework, functionalization does not improve ethanol adsorption capacity; instead, pristine UiO-66 shows the highest uptake due to its optimal pore size. Adsorption energy calculations on the (002) surface indicate that the -NO2 group exhibits the strongest affinity for oleic acid, owing to its strong electronegativity and synergistic effects with metal sites. For polyunsaturated fatty acids, adsorption performance depends critically on the compatibility between the hydrophobic pore environment and molecular conformation. Ethanol adsorption is governed primarily by hydrogen bonding and metal coordination. This study provides molecular-level insights into the structure–function relationships governing pre-reaction adsorption and mass transport mechanisms of functionalized UiO-66 in transesterification reactions, providing a theoretical foundation for the rational design of efficient pre-reaction microenvironments in biodiesel catalysts. Full article
(This article belongs to the Special Issue Catalysis for Sustainable Energy: Biodiesel and Biolubricant Innovations)
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22 pages, 3840 KB  
Article
Electrodeposited Pd/TiO2 Nanotube Arrays with Size-Controlled Pd for High-Performance UV and Visible-Light Photocatalytic Water Remediation
by Ayda Mehdaoui, Syrine Sassi, Rabia Benabderrahmane Zaghouani, Hafedh Dhiflaoui, Lofti Khezami, Amal Bouich, Farid Fadhillah, Amine Aymen Assadi, Jie Zhang, Anouar Hajjaji and Bernabé Mari Soucase
Catalysts 2026, 16(4), 350; https://doi.org/10.3390/catal16040350 - 14 Apr 2026
Viewed by 757
Abstract
Environmental contamination by persistent industrial dyes such as Amido Black demands highly efficient photocatalysts for advanced water treatment. Structural, chemical, and optical strategies based on TiO2 nanotube engineering are widely explored for this purpose. In this work, highly ordered TiO2 nanotube [...] Read more.
Environmental contamination by persistent industrial dyes such as Amido Black demands highly efficient photocatalysts for advanced water treatment. Structural, chemical, and optical strategies based on TiO2 nanotube engineering are widely explored for this purpose. In this work, highly ordered TiO2 nanotube arrays were fabricated by electrochemical anodization and subsequently decorated with Pd nanoparticles via potentiostatic electrodeposition (10–300 s), enabling precise control of Pd nanoparticle size and loading. The resulting materials were systematically characterized by SEM, TEM, XRD, XPS, UV–vis DRS, and PL spectroscopy, and their properties were correlated with the photocatalytic degradation of Amido Black under both UV and visible light irradiation. The study reveals a clear size-dependent duality in the role of Pd. For intermediate Pd nanoparticles (≈9 nm, 20 s), Pd behaves predominantly as an electron sink, forming an efficient Schottky junction with anatase TiO2 that markedly suppresses charge carrier recombination. This configuration yields ≈ 97% Amido Black removal after 120 min of UV irradiation, with an apparent rate constant about three times higher than that of bare TiO2 nanotubes. In contrast, for ultra-small Pd nanoparticles (≈6 nm, 10 s), interfacial defect states sensitize TiO2 to visible light, enabling ≈ 65% degradation after 270 min and a rate constant roughly four times higher than that of undecorated nanotubes under visible illumination. At long deposition times (≥150 s), Pd agglomeration leads to enhanced photoluminescence and markedly reduced photocatalytic activity, indicating increased recombination and less effective utilization of photogenerated charges. This provides a practical design rule to rationally tailor Pd–TiO2 nanotube photocatalysts for targeted UV or visible light applications in dye removal and broader environmental remediation scenarios Full article
(This article belongs to the Special Issue Applications of Catalysis in Organic Chemistry: Sustainable Catalysts for Sustainable Processes)
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4 pages, 149 KB  
Editorial
Overcoming Mass Transfer Limitations in Catalytic Oxidation and Reduction from Reactive-Species Engineering to Sustainable Catalyst Systems
by Weiwei Wang, Xiaxi Yao and Wei Chen
Catalysts 2026, 16(4), 349; https://doi.org/10.3390/catal16040349 - 14 Apr 2026
Viewed by 658
Abstract
Catalytic oxidation and reduction processes play a pivotal role in addressing critical challenges in environmental remediation, energy conversion, and chemical manufacturing [...] Full article
(This article belongs to the Special Issue Homogeneous and Heterogeneous Catalytic Oxidation and Reduction)
21 pages, 1829 KB  
Article
Photopolymer-Based Carbon with Iron Nanoparticles as Electrodes in Microbial Fuel Cells for Efficient Industrial Effluent Wastewater Treatment
by Ricardo da Silva Furlan, Noelia Corrochano, Rodrigo Brackmann, Mariana de Souza Sikora, Carlos Sotelo-Vazquez and Jose L. Diaz de Tuesta
Catalysts 2026, 16(4), 348; https://doi.org/10.3390/catal16040348 - 13 Apr 2026
Cited by 1 | Viewed by 663
Abstract
Accelerated industrial development demands the search for efficient remediation technologies. Microbial fuel cells (MFCs) have the capacity to remediate organic matter-rich effluent by utilizing bacteria as biocatalysts capable of oxidizing organic material while simultaneously producing electricity. In this paper, a novel electrode is [...] Read more.
Accelerated industrial development demands the search for efficient remediation technologies. Microbial fuel cells (MFCs) have the capacity to remediate organic matter-rich effluent by utilizing bacteria as biocatalysts capable of oxidizing organic material while simultaneously producing electricity. In this paper, a novel electrode is prepared through the carbonization of a tailored photopolymer with iron nanoparticles and carbon black (C-iNPCB) and its performance tested as an anode using dual chamber MFCs for the remediation of paper recycling plant effluent. Its efficiency is compared to a graphite rod (GR) and a carbon black-coated 3D-printed structure (3D-CB). The paper effluent containing chemical oxygen demand 5.0 g/L was used as feedstock in the MFCs. The GR anode (0.91 A/m2; 0.32 W/m2) and 3D-CB anode (0.88 A/m2; 0.30 W/m2) both achieved 56% COD removal, while the C-iNPCB-anode (5.71 A/m2; 3.75 W/m2) was the best performing, with over 80% COD removal. The photopolymerized doped anode exhibited superior performance in terms of both organic matter oxidation and conductivity, indicating higher effectiveness of this type of electrode in MFC technology. Full article
(This article belongs to the Special Issue Catalytic Mechanisms of Nanomaterials in Energy and Environmental Applications)
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23 pages, 7182 KB  
Article
Enhanced Structural, Optical, Photocatalytic, and Cytotoxic Properties of CuO Doped with rGO: A One-Step Hydrothermal Synthesis Approach
by Amirah S. Alahmari, Mohamed M. Badran, Mohammed ALSaeedy, Syed Mansoor Ali, M. A. Jowhari and ZabnAllah M. Alaizeri
Catalysts 2026, 16(4), 347; https://doi.org/10.3390/catal16040347 - 13 Apr 2026
Viewed by 636
Abstract
The current work aims to enhance the structural, optical, photocatalytic, and cytotoxic properties of CuO NPs at varied rGO concentrations of 5% and 10%. In the present work, a one-step hydrothermal method was successfully applied to prepare rGO/CuO NCs at different concentrations of [...] Read more.
The current work aims to enhance the structural, optical, photocatalytic, and cytotoxic properties of CuO NPs at varied rGO concentrations of 5% and 10%. In the present work, a one-step hydrothermal method was successfully applied to prepare rGO/CuO NCs at different concentrations of RGO. The novelty of this work was to enhance the structural, optical, photocatalytic, and cytotoxic properties of CuO using the addition of rGO sheets. XRD, TEM, SEM-EDX, XPS, FTIR, UV-vis, PL, and DLS techniques were used to characterize the prepared samples. XRD data confirmed the formation of the monoclinic phase of CuO with a decrease in crystallite size, from 21.14 nm for CuO to 16.94 nm for the 10% rGO/CuO NCs nanocomposite. SEM and TEM images verified the uniform anchoring and excellent dispersion of CuO nanoparticles on the rGO sheets, and the EDX spectra showed the presence of Cu, O, and C elements in the obtained rGO/CuO NCs. DLS measurements showed that the hydrodynamic radius dropped from 69.98 ± 17.81 nm for CuO to 51.72 ± 10.48 nm for 10% rGO/CuO NCs. The zeta potential values remained negative for all samples, ranging from −20.50 ± 8.69 mV for CuO to −25.60 ± 9.08 mV for 10% rGO/CuO NCs, suggesting enhanced colloidal stability with rGO incorporation. Furthermore, FTIR and XPS analyses confirmed that Cu–O–C bonding formed between CuO and rGO. UV-Vis analysis revealed a redshift in the absorption edges as rGO content increased, reducing the band gap from 3.65 eV to 3.60 eV. Additionally, PL spectra showed a marked reduction in emission intensity due to a decrease in the recombination rate between electron (e−)–holes (h+) pairs. The CuO/(10%)rGO NCs showed the best photocatalytic performance with a 93.56% degradation of methylene blue (MB) after 120 min under UV irradiation, and followed pseudo-first-order kinetics with k = 0.0203 min−1. Cytotoxicity studies on HT1080 cells showed a dose-dependent decrease in viability. 10% rGO/CuO NCs exhibited the highest cytotoxicity effect, resulting in 58% and 50% viability at 1.4 mg/mL, respectively. The presented results showed that the presence of rGO in CuO NPs played a role in enhancing the structural stability, charge mobility, and biological reactivity of Cu NPs. This study highlighted that the rGO/CuO NCs are a promising multi-functional material for environmental and biomedical applications. Full article
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39 pages, 7672 KB  
Article
Functional Expression of the Aromatic Prenyltransferase NphB in Chlamydomonas reinhardtii Highlights Challenges in Cannabinoid Biocatalysis
by Serge Basile Nouemssi, Ayoub Bouhadada, Rémy Beauchemin, Alexandre Custeau, Sarah-Ève Gélinas, Natacha Merindol, Fatma Meddeb-Mouelhi, Hugo Germain and Isabel Desgagné-Penix
Catalysts 2026, 16(4), 346; https://doi.org/10.3390/catal16040346 - 13 Apr 2026
Viewed by 949
Abstract
Cannabinoids are high-value bioactive compounds whose sustainable production remains challenging, prompting interest in biocatalytic and microbial platforms as alternatives to plant extraction. In this study, we investigated the heterologous expression and functionality of two key cannabinoid-related enzymes in the photosynthetic microalga Chlamydomonas reinhardtii [...] Read more.
Cannabinoids are high-value bioactive compounds whose sustainable production remains challenging, prompting interest in biocatalytic and microbial platforms as alternatives to plant extraction. In this study, we investigated the heterologous expression and functionality of two key cannabinoid-related enzymes in the photosynthetic microalga Chlamydomonas reinhardtii: the aromatic prenyltransferase, NphBG286S/Y288A from Streptomyces sp., and the plant-derived cannabidiolic acid synthase (CBDAS) from Cannabis sativa. Codon-optimized genes were introduced into the nuclear genome of C. reinhardtii using several construct configurations and promoters, and stable transformants were generated and characterized for genomic integration, transcript accumulation, protein production, enzymatic activity, and cannabinoid-related metabolite formation. While NphB protein accumulation was achieved under the PSAD promoter control, CBDAS was not detected at the protein level under any condition tested. In vitro enzymatic assays using soluble algal protein extracts from NphB-expressing lines confirmed catalytic activity, yielding cannabigerolic acid (CBGA), reaching up to 633 ± 58 µg L−1. However, no CBGA production was detected in vivo, despite substrate supplementation. These results indicate that, although bacterial prenyltransferase can be functionally expressed in C. reinhardtii, efficient metabolic conversion in vivo is limited by cellular and biochemical constraints, including substrate availability, intracellular compartmentalization, and potential competition with endogenous pathways. In contrast, the absence of detectable CBDAS highlights the challenges associated with expressing complex plant oxidocyclases in this photosynthetic host. Overall, this work provides mechanistic insights into enzyme compatibility and metabolic bottlenecks in microalgal systems and outlines key considerations for the future development of photosynthetic platforms for cannabinoid biocatalysis. Full article
(This article belongs to the Special Issue Biocatalysis and Biosynthesis: Opportunities and Challenges)
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15 pages, 1956 KB  
Article
Metal-Free h-BN/Carbon Nano-Onion Heterostructure Electrocatalyst with Enhanced Hydrogen Evolution Activity Under Acidic Media
by Shakeelur Raheman, Khursheed B. Ansari and Nilesh Salunke
Catalysts 2026, 16(4), 345; https://doi.org/10.3390/catal16040345 - 13 Apr 2026
Viewed by 618
Abstract
Developing effective metal-free electrocatalysts for acidic hydrogen evolution is challenging because both catalytic activity and electronic conductivity must be optimized simultaneously. Here, h-BN/carbon nano-onion (CNO) hybrid electrocatalysts were synthesized by integrating layered hexagonal boron nitride with conductive carbon nano-onions to generate accessible heterointerfaces [...] Read more.
Developing effective metal-free electrocatalysts for acidic hydrogen evolution is challenging because both catalytic activity and electronic conductivity must be optimized simultaneously. Here, h-BN/carbon nano-onion (CNO) hybrid electrocatalysts were synthesized by integrating layered hexagonal boron nitride with conductive carbon nano-onions to generate accessible heterointerfaces for the hydrogen evolution reaction (HER). Structural characterization by XRD, SEM/TEM, and STEM-EDS confirmed intimate contact between h-BN sheets and quasi-spherical CNO domains. Similarly, XPS revealed B–N-rich frameworks with interfacial B–C/C–N surface environments and oxygen-associated defect sites. Among the prepared compositions, the h-BN/CNO20 eletrocatalyst exhibited the best apparent HER performance in 0.5 M H2SO4, delivering an overpotential of ~270 mV at 5 mA cm−2 and a Tafel slope of 76 mV dec−1, along with stable chronoamperometric behavior for 15 h. The improved electrocatalytic activity is due to the enhanced charge transport through the CNO network, suppression of h-BN restacking, increased exposure of interfacial sites, and charge redistribution across B–N/C heterojunctions. These findings identify h-BN/CNO20 as the optimum composition within this series and demonstrate that heterointerface engineering between boron nitride and curved graphitic nanocarbons is a promising strategy for developing metal-free HER electrocatalysts. However, further validation using a non-Pt counter electrode is necessary to confirm intrinsic catalytic activity. Full article
(This article belongs to the Special Issue Advanced Catalysis for Energy and a Sustainable Environment)
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17 pages, 4645 KB  
Article
Constructing a CoFe2O4-Impregnated Ceramic Membrane with Catalytic Ozonation Capability for Mitigating Irreversible Membrane Fouling
by Jiahao Zhou, Yuxuan Yang, Zhe Yu, Yiming Yang, Fengtao Chen and Xiufang Chen
Catalysts 2026, 16(4), 344; https://doi.org/10.3390/catal16040344 - 11 Apr 2026
Viewed by 759
Abstract
To in situ and efficiently degrade irreversible membrane contaminants under mild conditions, SiC ceramic membranes (CMs) were imparted a catalytic ozonation functionality. A spinel-type CoFe2O4 catalyst was fabricated via a citrate-assisted sol–gel method and subsequently impregnated into the macropores of [...] Read more.
To in situ and efficiently degrade irreversible membrane contaminants under mild conditions, SiC ceramic membranes (CMs) were imparted a catalytic ozonation functionality. A spinel-type CoFe2O4 catalyst was fabricated via a citrate-assisted sol–gel method and subsequently impregnated into the macropores of SiC ceramic membranes through a urea-assisted one-step combustion technique. The as-prepared catalytic membranes (CoFe2O4-CM) were systematically characterized by SEM, EDS, XRD and XPS techniques, and the catalytic ozonation performance was evaluated in an integrated catalytic ozonation–membrane separation system (CoFe2O4-CM/O3). A flux recovery rate (FRR) of 93.33% was achieved at an ozone concentration of 70.27 mg·L−1 within 30 min, indicating that a catalytic self-cleaning membrane was successfully developed. The possible catalytic reaction mechanism was elucidated by identifying reactive oxygen species generated using free radical quenching tests and electron paramagnetic resonance (EPR) analysis. This study offers a promising and environmentally friendly strategy for ceramic membrane cleaning in various membrane separation fields. Full article
(This article belongs to the Special Issue Advanced Catalysts for Energy Conversion and Environmental Protection)
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23 pages, 5239 KB  
Article
Effect of Acid-Controlled SBA-15 on Catalytic Performance of CaO/Cr-SBA-15 Dual-Functional Materials
by Daoguang Yu, Wei Gao, Mingdong Li, Yangzhou Guo, Li Xu, Ziying Shi, Miaomiao Hao and Xiaohan Ren
Catalysts 2026, 16(4), 343; https://doi.org/10.3390/catal16040343 - 11 Apr 2026
Viewed by 619
Abstract
Based on the acid-sensitive characteristics of SBA-15 during synthesis, this study varied the acid types, pH values, and mixed acid ratios during SBA-15 preparation to enhance the performance of CaO/Cr-SBA-15 dual-functional materials (DFMs) in integrated CO2 capture and utilization for oxidative dehydrogenation [...] Read more.
Based on the acid-sensitive characteristics of SBA-15 during synthesis, this study varied the acid types, pH values, and mixed acid ratios during SBA-15 preparation to enhance the performance of CaO/Cr-SBA-15 dual-functional materials (DFMs) in integrated CO2 capture and utilization for oxidative dehydrogenation of ethane (ICCU-ODHE). It was found that the SBA-15 support synthesized in an H2SO4 environment exhibited a high specific surface area and abundant surface silanol groups, which facilitated the dispersion of Cr and increased the proportion of Cr6+ active sites, thereby achieving the highest ethane conversion. In contrast, the moderate surface acidity of the HCl-prepared support facilitated the selective dehydrogenation of ethane over Cr active sites, effectively inhibiting side reactions and maximizing ethylene selectivity. Further investigations into the effects of pH and mixed acids revealed that pH 1 is optimal for SBA-15 preparation. At this value, the support reached its maximum mesoporous ordering and specific surface area, allowing for optimal Cr dispersion. Consequently, the ethane conversion, ethylene selectivity, and DFM yield all reached their peak values. Any deviation from this pH led to degradation of the support structure and reduced Cr dispersion, resulting in a significant decline in catalytic performance. Among the tested materials, the CaO/Cr-SBA-15-Cl-S DFM synthesized with an HCl-H2SO4 mixed acid demonstrated the superior reactivity, achieving an ethylene yield of 33.95%. Long-term cycling tests indicated that the material possesses good stability, with its performance attenuation primarily attributed to coking and adsorbent sintering. Full article
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18 pages, 2252 KB  
Article
Fabrication of TiO2-WO3 S-Scheme Heterojunction for High-Efficiency Visible-Light Photocatalysis
by Yang Deng, Shuhong Wu and Jun Zhu
Catalysts 2026, 16(4), 342; https://doi.org/10.3390/catal16040342 - 10 Apr 2026
Viewed by 1283
Abstract
Driven by the progress of sustainable development, environmental remediation and water treatment have become increasingly important. Photocatalysis, capable of degrading pollutants through light (especially visible light) irradiation, has received widespread research attention. Titanium dioxide(TiO2) is a promising photocatalyst, yet its practical [...] Read more.
Driven by the progress of sustainable development, environmental remediation and water treatment have become increasingly important. Photocatalysis, capable of degrading pollutants through light (especially visible light) irradiation, has received widespread research attention. Titanium dioxide(TiO2) is a promising photocatalyst, yet its practical use is limited by low visible-light utilization and rapid photogenerated charge recombination. Herein, an S-scheme TiO2-WO3(Tungsten trioxide) heterojunction was successfully fabricated; the difference in Fermi levels induces a built-in electric field directed from TiO2 to WO3, which thus constructs the S-scheme heterojunction. The as-prepared heterojunction exhibits a markedly enhanced transient photocurrent density, with the carrier lifetime prolonged from 2.69 ns to 41.61 ns. Under visible-light irradiation, the heterojunction achieves a methylene blue (MB) removal efficiency of over 95% within 90 min, and its pseudo-first-order kinetic rate constant k reaches 0.032 min−1, which is approximately 16 times that of pure TiO2. Radical trapping experiments confirm that the dominant active species responsible for the catalytic process are photogenerated holes and the hydroxyl radicals derived therefrom. Full article
(This article belongs to the Special Issue Photocatalysis and Electrocatalysis for Water Remediation)
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23 pages, 1255 KB  
Review
Solar-Driven Catalytic Wastewater Treatment: A Unified Photonic–Thermal Framework for Advanced Oxidation and Disinfection Mechanisms
by Carlos E. Barrera-Díaz, Bernardo A. Frontana-Uribe, Gabriela Roa-Morales, Patricia Balderas-Hernández and Pedro Avila-Pérez
Catalysts 2026, 16(4), 341; https://doi.org/10.3390/catal16040341 - 10 Apr 2026
Viewed by 921
Abstract
Increasing water demand and the rising complexity of wastewater matrices, driven by pharmaceuticals, personal care products, and recalcitrant industrial contaminants, require advanced catalytic solutions capable of efficient mineralization under sustainable conditions. Solar-driven processes have attracted growing attention; however, ultraviolet disinfection, heterogeneous photocatalysis, and [...] Read more.
Increasing water demand and the rising complexity of wastewater matrices, driven by pharmaceuticals, personal care products, and recalcitrant industrial contaminants, require advanced catalytic solutions capable of efficient mineralization under sustainable conditions. Solar-driven processes have attracted growing attention; however, ultraviolet disinfection, heterogeneous photocatalysis, and photo-Fenton systems are commonly treated as independent approaches without mechanistic integration. This review presents a unified photonic–thermal catalytic framework for solar-driven wastewater treatment, emphasizing the interplay between photon absorption, charge-carrier separation, reactive oxygen species generation, and radical-mediated oxidation pathways. The contributions of ultraviolet, visible, and infrared radiation are analyzed in terms of catalyst activation, persulfate and ozone activation mechanisms, and temperature-enhanced reaction kinetics governed by Arrhenius behavior. Particular attention is given to photothermal effects that modulate surface reaction rates, mass transfer, and catalyst stability. By integrating mechanistic insights with reactor-level considerations, this work provides a rational basis for the design of robust solar catalytic systems with enhanced activity, selectivity, and scalability for real wastewater applications. Full article
(This article belongs to the Special Issue Photocatalyzed and Electrochemical Processes for a Cleaner Environment, 2nd Edition)
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