Catalysts

17 pages, 1172 KiB

Open AccessArticle

Calcination Temperature-Induced Morphology Transformation in WO₃ Flower-like Thin Films for Photocatalytic Wastewater Treatment

by João Lincho, Paweł Mazierski, Tomasz Klimczuk, Rui C. Martins, João Gomes and Adriana Zaleska-Medynska

Catalysts 2025, 15(3), 207; https://doi.org/10.3390/catal15030207 - 21 Feb 2025

Abstract

WO₃ nanoflowers were synthesized via anodization and subsequently calcined in air at different temperatures (200–700 °C) to evaluate their photocatalytic activity. The samples were characterized in terms of their morphological, crystallite, and optical properties. Anodization produced WO₃ hydrate with a layer [...] Read more.

WO₃ nanoflowers were synthesized via anodization and subsequently calcined in air at different temperatures (200–700 °C) to evaluate their photocatalytic activity. The samples were characterized in terms of their morphological, crystallite, and optical properties. Anodization produced WO₃ hydrate with a layer thickness of ~1.2 µm, which was transformed into WO₃ after heating. All samples exhibited monoclinic phase, with Raman shift intensity increasing with the calcination temperature. Some residual WO₃·H₂O was detected at certain temperatures. The calculated bandgap energy ranged from 2.49 to 2.67 eV, with higher calcination temperatures leading to lower absorbance in the UV region. The photodegradation of phenol under UV-Vis radiation reached 35% in 60 min for WO₃_700 °C, where the photocatalyst suffered a morphological transformation from a nanoflower to nanogranular structure, accompanied by increased crystallinity. Under visible light, the phenol abatement was limited, achieving 1–3% degradation. The WO₃ surface is likely negatively charged at the solution’s pH (5.6), which may explain the low phenol adsorption (~1%). Full article

(This article belongs to the Special Issue Advances in Photocatalytic Wastewater Purification, 2nd Edition)

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19 pages, 11166 KiB

Open AccessArticle

One-Pot In Situ Synthesis of Porous Vanadium-Doped g-C₃N₄ with Improved Photocatalytic Removal of Pharmaceutical Pollutants

by Yafeng Huang, Rui Pang, Shanshan Sun, Xiufang Chen, Fengtao Chen and Wangyang Lu

Catalysts 2025, 15(3), 206; https://doi.org/10.3390/catal15030206 - 21 Feb 2025

Abstract

The peroxymonosulfate (PMS)-assisted photocatalytic process has shown considerable potential for the treatment of wastewater. g-C₃N₄-based catalysts are widely applied to eliminate organic pollutants in wastewater. However, the bulk catalyst prepared by dicyandiamide has the drawback of a low surface [...] Read more.

The peroxymonosulfate (PMS)-assisted photocatalytic process has shown considerable potential for the treatment of wastewater. g-C₃N₄-based catalysts are widely applied to eliminate organic pollutants in wastewater. However, the bulk catalyst prepared by dicyandiamide has the drawback of a low surface area (10 m²/g), while the porous catalyst prepared by urea suffers from a low catalyst yield based on urea (3.5%). To address these challenges, a porous V-doped carbon nitride (V/CN) was designed through one-step thermal polymerization using urea and dicyandiamide as the carbon nitride precursor and NH₄VO₃ as the V precursor. When the ratio of urea to dicyandiamide was 10:1, the yield of V/CN was improved, while it maintained a rich porous structure with a specific surface area (64.6 m²/g). The synergetic effect of V doping and nanosheet and hollow tubular structures facilitated the separation of photogenerated carriers, leading to boosting the photocatalytic activity of g-C₃N₄ in the PMS system. V/CN(10:1) could completely degrade CBZ within 20 min, exhibiting an equivalent catalytic efficiency comparable to that of V/CN prepared by urea (V/UCN), while markedly surpassing both V/DCN and CN prepared by urea alone (UCN) in performance. This study presents an economical and effective approach for the photocatalytic degradation of pharmaceutical pollutants in aquatic environments. Full article

(This article belongs to the Special Issue Recent Advances in Photocatalytic Treatment of Pollutants in Water)

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27 pages, 4982 KiB

Open AccessFeature PaperReview

Design and Synthesis of Self-Supported Water-Splitting Transition Metal-Based Electrocatalysts via Electrospinning

by Sai Che, Yu Jia and Yongfeng Li

Catalysts 2025, 15(3), 205; https://doi.org/10.3390/catal15030205 - 21 Feb 2025

Abstract

Recent advances in transition metal-based electrocatalysts have significantly enhanced the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water electrocatalysis. Self-supported electrodes, where active sites are directly integrated with substrates, offer superior kinetics and stability compared to traditional powder-based electrocatalysts. The [...] Read more.

Recent advances in transition metal-based electrocatalysts have significantly enhanced the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water electrocatalysis. Self-supported electrodes, where active sites are directly integrated with substrates, offer superior kinetics and stability compared to traditional powder-based electrocatalysts. The electrospinning technique is particularly effective for fabricating self-supported electrocatalysts with high surface areas, porosity, and uniform distribution of active sites, leading to improved catalytic performance. Despite extensive research on self-supported electrocatalysts, a comprehensive review focusing on those developed via electrospinning remains scarce. This review provides a detailed overview of the electrospinning process, the fundamental principles of water electrocatalysis, and recent progress in the development of transition metal-based electrocatalysts fabricated through this approach. Full article

(This article belongs to the Special Issue Feature Review Papers in Electrocatalysis)

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16 pages, 1367 KiB

Open AccessFeature PaperReview

Advances and Challenges in Zeolite-Based Catalysts for the Selective Catalytic Oxidation of Ammonia

by Xiaoxin Chen, Jun Huang and Guoju Yang

Catalysts 2025, 15(3), 204; https://doi.org/10.3390/catal15030204 - 21 Feb 2025

Abstract

Ammonia (NH₃) emissions from mobile sources pose significant environmental challenges, contributing to air pollution, ecosystem degradation, and climate change. The selective catalytic oxidation of NH₃ (NH₃-SCO) offers a sustainable solution by converting NH₃ into nitrogen and water, [...] Read more.

Ammonia (NH₃) emissions from mobile sources pose significant environmental challenges, contributing to air pollution, ecosystem degradation, and climate change. The selective catalytic oxidation of NH₃ (NH₃-SCO) offers a sustainable solution by converting NH₃ into nitrogen and water, yet designing catalysts that balance high efficiency, selectivity, and stability under operational conditions remains a critical challenge. This review provides a comprehensive overview of zeolite-based catalysts, renowned for their high surface area, tunable pore structures, and exceptional hydrothermal stability, which make them ideal for NH₃-SCO applications. The review synthesizes recent advancements in catalyst design, emphasizing innovative architecture, the role of zeolite frameworks in active site dispersion, and strategies for optimizing catalytic architectures. Key insights include an enhanced understanding of NH₃-SCO reaction mechanisms, progress in mitigating catalyst deactivation caused by poisoning and sintering, and the development of bimetallic and core-shell catalysts to improve performance and durability. Current limitations, including the sensitivity of catalysts to operational environments and scalability issues, are critically analyzed, and potential strategies for overcoming these barriers are proposed. This review highlights the state-of-the-art in zeolite-based NH₃-SCO catalysis, offering valuable insights into the fundamental and applied aspects of catalyst design. The findings presented here provide a roadmap for future innovations in environmental catalysis, paving the way for more efficient and robust solutions to ammonia emission control. Full article

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

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27 pages, 3473 KiB

Open AccessReview

Current Research Status and Future Perspective of Ni- and Ru-Based Catalysts for CO₂ Methanation

by Muhammad Usman, Seetharamulu Podila, Majed A. Alamoudi and Abdulrahim A. Al-Zahrani

Catalysts 2025, 15(3), 203; https://doi.org/10.3390/catal15030203 - 21 Feb 2025

Abstract

Using anthropogenic carbon dioxide (CO₂) as a feedstock for the production of synthetic fuel has gained significant attention in recent years. Among the various CO₂ conversion pathways, the production of synthetic natural gas via CO₂ methanation holds promise because [...] Read more.

Using anthropogenic carbon dioxide (CO₂) as a feedstock for the production of synthetic fuel has gained significant attention in recent years. Among the various CO₂ conversion pathways, the production of synthetic natural gas via CO₂ methanation holds promise because of its potential for both carbon recycling and renewable energy storage. Nickel (Ni) and ruthenium (Ru) are the dominant metals employed as catalysts in the CO₂ methanation reaction. This review summarizes the research landscape of Ni- and Ru-based catalysts over the last ten years. Bibliometric analysis revealed that China has the highest number of publications, the Chinese Academy of Sciences is the foremost academic institution, and the International Journal of Hydrogen Energy is the leading journal in this area of research. The publication trend revealed that research on Ni-based catalysts is published at almost four times the rate of Ru-based catalysts. Despite growth in research, problems with catalyst stability and kinetics still exist. The latest research on various catalytic systems, including supported, bimetallic, and single-atom catalysts and the fundamental challenges associated with the CO₂ methanation process are reviewed. This review provides a new angle for future studies on catalysts based on non-noble Ni and noble Ru metals and opens the way for additional research in this area. Full article

(This article belongs to the Special Issue Non-precious Metal Catalysts for Energy and Environment-Related Applications)

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11 pages, 911 KiB

Open AccessCommunication

Sustainable Synthesis of α-Glucosidase Inhibitors by Gas-Free Pd-Carbonylation of Nature-Based Hydroxytyrosol

by Francesco Messa, Domenico Armenise, Anselma Liturri, Maria Grazia Perrone, Serena Perrone and Antonio Salomone

Catalysts 2025, 15(3), 202; https://doi.org/10.3390/catal15030202 - 21 Feb 2025

Abstract

This study outlines the sustainable synthesis of novel hydroxytyrosol (HT) and tyrosol (T) ester derivatives via a Pd-catalyzed alkoxycarbonylation of aromatic iodides. The high sustainability of the process is attributed to the use of (1) a solid carbon monoxide source, Mo(CO)₆, [...] Read more.

This study outlines the sustainable synthesis of novel hydroxytyrosol (HT) and tyrosol (T) ester derivatives via a Pd-catalyzed alkoxycarbonylation of aromatic iodides. The high sustainability of the process is attributed to the use of (1) a solid carbon monoxide source, Mo(CO)₆, in place of dangerous gaseous CO; (2) a biomass-derived organic solvent, CPME (cyclopentyl methyl ether); (3) naturally occurring hydroxylated compounds, such as HT and T, which could be derived from agricultural waste rather than produced from petroleum-based sources. The method enables the regioselective preparation of various HT and T esters in a short reaction time (4–8 h), under mild temperatures (80 °C), and with moderate-to-excellent yields (62–93%). Moreover, in vitro biological tests have demonstrated that, in addition to the well-known antioxidant properties typical of natural phenolic compounds such as HT and T, some of the newly synthesized derivatives have a safe profile and are effective inhibitors of the α-glucosidase with potential application in the management of hyperglycemia. This synthetic approach offers a promising strategy for exploring biologically relevant chemical space, bridging the gap between natural products and sustainable drug synthesis. Full article

(This article belongs to the Special Issue Recent Advances in Palladium-Catalyzed Organic Synthesis)

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18 pages, 6905 KiB

Open AccessArticle

Comparative Evaluation of Photocatalytic Efficiency Measurement Techniques Through Rhodamine B Degradation in TiO₂-Based Cementitious Materials

by Fabíula Pereira Lessa, Orlando Lima, Jr., Élida Margalho, Behzad Zahabizadeh, Vítor M. C. F. Cunha, Eduardo Pereira, Aires Camões, Manuel F. M. Costa, Iran Rocha Segundo and Joaquim Carneiro

Catalysts 2025, 15(3), 201; https://doi.org/10.3390/catal15030201 - 20 Feb 2025

Abstract

Self-cleaning cementitious materials, particularly with TiO₂-based photocatalytic coatings, offer significant benefits by reducing surface deterioration and maintenance requirements, even in harsh urban environments. Despite the growing interest in self-cleaning cementitious materials, an international standard test method to calculate their efficiency has [...] Read more.

Self-cleaning cementitious materials, particularly with TiO₂-based photocatalytic coatings, offer significant benefits by reducing surface deterioration and maintenance requirements, even in harsh urban environments. Despite the growing interest in self-cleaning cementitious materials, an international standard test method to calculate their efficiency has not yet been established for this specific type of substrate. The objective of this study was to evaluate and compare three different techniques for assessing the photocatalytic efficiency (PE) of cementitious materials coated with TiO₂: (i) spectrophotometric colorimetry (SPC); (ii) digital image processing-based colorimetry (DIP); and (iii) UV-Vis spectrophotometry (UV-Vis). Rhodamine B (RhB) was used as a model pollutant, and the photocatalytic efficiency was monitored under UV-Vis light. The results showed that each method has distinct advantages and specific challenges. SPC proved to be a practical and efficient approach, similarly to DIP, which was also accessible, providing reliable and accurate measurements. UV-Vis stood out for its precision but required careful application on cement-based substrates due to their unique porosity and adsorption characteristics. These results underscore the complementary potential of these techniques and highlight the importance of developing standardized protocols that integrate their strengths to facilitate the wider adoption of self-cleaning materials. Full article

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

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15 pages, 6170 KiB

Open AccessArticle

Geometric Structure-Dependent Catalyst Performance in CH₄ Reforming Using Ni-Based Catalysts

by Dongdong Dong, Yanhui Li, Min Liu, Bingwen Lu, Xingchen Yan, Zhaoyang Deng, Cheng Chang and Kesong Zhou

Catalysts 2025, 15(3), 200; https://doi.org/10.3390/catal15030200 - 20 Feb 2025

Abstract

The specific surface area, porosity, and mechanical properties of a catalyst are critical factors that significantly influence its performance. However, conventional preparation techniques are incapable of optimizing these properties simultaneously. Here, we present the performance of three kinds of catalysts with different geometric [...] Read more.

The specific surface area, porosity, and mechanical properties of a catalyst are critical factors that significantly influence its performance. However, conventional preparation techniques are incapable of optimizing these properties simultaneously. Here, we present the performance of three kinds of catalysts with different geometric structures. Our findings indicated that the porosity, specific surface area, and mechanical properties of the 3D-printed catalysts achieved an optimal balance, exhibiting enhanced catalytic efficiency and mechanical integrity compared to commercial catalysts. Furthermore, the excellent ductility of the metal catalyst supports effectively prevented catalyst pulverization caused by carbon deposition and the thermal expansion of the supports. These results demonstrate that 3D printing technology can open up novel avenues for catalyst preparation, especially for metal-supported catalysts. The potential of metal additive manufacturing in chemical engineering is substantial, promising transformative advancements in the design and fabrication of catalytic converters and reactors. Full article

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10 pages, 2235 KiB

Open AccessFeature PaperArticle

Enhancing C-C Coupling in CO₂ Electroreduction by Engineering Pore Size of Porous Carbon-Supported Cu Catalysts

by Aiming Huang, Jiayue Yu, Junjun Zhang, Yifan Zhang, Yang Wu, Yong Wang and Wen Luo

Catalysts 2025, 15(3), 199; https://doi.org/10.3390/catal15030199 - 20 Feb 2025

Abstract

The electroreduction of CO₂ (CO₂RR) is a promising and environmentally sustainable approach to closing the carbon cycle. However, achieving high activity and selectivity for multicarbon (C₂₊) products remains a significant challenge due to the complexity of reaction pathways. [...] Read more.

The electroreduction of CO₂ (CO₂RR) is a promising and environmentally sustainable approach to closing the carbon cycle. However, achieving high activity and selectivity for multicarbon (C₂₊) products remains a significant challenge due to the complexity of reaction pathways. In this study, porous carbon-supported copper catalysts (CuHCS) with pore sizes of 120 nm (CuHCS120) and 500 nm (CuHCS500) were synthesized to tailor the microenvironment at the electrode–electrolyte interface and enhance product selectivity. CuHCS120 achieved a maximum faradaic efficiency (FE) for C₂₊ products of 46%, double that of CuHCS500 (23%). In contrast, CuHCS500 showed a higher FE for CO (36%) compared to CuHCS120 (14%) at the same potential. In-depth ex situ and in situ investigations revealed that smaller pores promote the enrichment and adsorption of *CO intermediates, thereby enhancing C–C coupling and the formation of C₂₊ products. These findings underscore the critical role of structural confinement in modulating the catalytic microenvironment and provide valuable insights for the rational design of advanced catalysts for CO₂RR. Full article

(This article belongs to the Special Issue Nanostructured Materials for Photocatalysis and Electrocatalysis)

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17 pages, 4390 KiB

Open AccessArticle

Influence of Preparation Method on Structure and Photocatalytic Performance of Bi₂MoO₆

by Qiuqin Wang, Jinlong Ge, Wei Liu, Hanyu Zhang and Ruochen Li

Catalysts 2025, 15(3), 198; https://doi.org/10.3390/catal15030198 - 20 Feb 2025

Abstract

The emergence of bismuth molybdate (Bi₂MoO₆) as a promising visible-light catalyst has prompted researchers to increasingly focus on its investigation. To elucidate the impact of different preparation methods on the morphology and photocatalytic properties of Bi₂MoO₆ [...] Read more.

The emergence of bismuth molybdate (Bi₂MoO₆) as a promising visible-light catalyst has prompted researchers to increasingly focus on its investigation. To elucidate the impact of different preparation methods on the morphology and photocatalytic properties of Bi₂MoO₆, samples were synthesized via solvothermal, in situ conversion, solution combustion, precipitation, and sol-gel techniques. The physicochemical properties of Bi₂MoO₆ were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis (PSA), fluorescence, and photocurrent measurements. The materials’ ability to degrade Rhodamine B (RhB) was evaluated. The results demonstrated that the crystallinity, morphology, bandgap width, and photogenerated carrier recombination of Bi₂MoO₆ varied significantly depending on the preparation method. Among these methods, the solvothermal route proved most effective, yielding Bi₂MoO₆ with the highest photocatalytic activity, achieving 97.5% RhB degradation within 25 min of light exposure. The low photogenerated carrier recombination rate was attributed to the large specific surface area and narrow bandgap (2.71 eV). This study provides valuable insights into preparing Bi₂MoO₆ with enhanced photocatalytic properties. Full article

(This article belongs to the Section Photocatalysis)

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16 pages, 4129 KiB

Open AccessArticle

Rapid Analysis of Chemical Oxygen Demand by Using a SPE Sensor Based on rGO/Cu/Ni Composite Catalyst Synthesized via One-Step Chemical Reduction

by Yu Zhou, Kaixin Zheng, Yihao Zhang, Yong Zhao, Zhi Ouyang, Xu Zhang and Xianhua Liu

Catalysts 2025, 15(3), 197; https://doi.org/10.3390/catal15030197 - 20 Feb 2025

Abstract

Black-odorous water (BOW) in urban areas poses significant risks to water safety and human health. Chemical oxygen demand (COD) is a critical parameter for the control and monitoring of BOW. However, traditional methods for COD determination are expensive, time-consuming, and involve the use [...] Read more.

Black-odorous water (BOW) in urban areas poses significant risks to water safety and human health. Chemical oxygen demand (COD) is a critical parameter for the control and monitoring of BOW. However, traditional methods for COD determination are expensive, time-consuming, and involve the use of hazardous chemicals. In this study, reduced graphene oxide (rGO) and transitional metal particles (Cu, Ni) were used as working electrode materials for facile on-site determination of COD in BOW. Three composite materials (rGO/Cu, rGO/Ni, and rGO/Cu/Ni) were synthesized by one-step chemical reduction with different ratios, and their microstructure and chemical composition were characterized. Glucose solution and real water were used to evaluate the electrocatalytic performance of the different sensors. The ternary composite (rGO/Cu/Ni) screen-printed electrode sensor demonstrated excellent performance in COD analysis, with a low limit of detection (18.9 mg L⁻¹), a broad linear detection range from 53 to 1500 mg L⁻¹, and a 1.61% relative error for real water samples. The testing results were highly consistent with those obtained using the standard chromium sulfate method. This study offers promising prospects for the mass production of cost-effective COD electrochemical sensors, facilitating real-time, on-site monitoring of water bodies in major urban areas. Full article

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

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16 pages, 5171 KiB

Open AccessFeature PaperArticle

Effect of the Catalyst Support on the NO_X Formation During Combustion of NH₃ SOFC Off-Gas

by Tobias Weissenberger, Ralf Zapf, Helmut Pennemann and Gunther Kolb

Catalysts 2025, 15(3), 196; https://doi.org/10.3390/catal15030196 - 20 Feb 2025

Abstract

Ammonia has attracted much interest as a potential green and renewable hydrogen carrier or energy vector. Compared to hydrogen, ammonia offers several advantages. For example, ammonia has a significantly higher energy density and can be liquefied at room temperature at a moderate pressure [...] Read more.

Ammonia has attracted much interest as a potential green and renewable hydrogen carrier or energy vector. Compared to hydrogen, ammonia offers several advantages. For example, ammonia has a significantly higher energy density and can be liquefied at room temperature at a moderate pressure of 8 bars. While ammonia can be cracked to supply hydrogen, it is also possible to convert it directly into high-temperature solid oxide fuel cells (SOFCs) to generate electricity. The Ship-FC project aims to install an ammonia-fed 2MW SOFC system on board the vessel Viking energy to demonstrate the feasibility of zero CO₂ emission shipping. For this NH₃ SOFC system, a catalytic afterburner is required to remove the hydrogen and ammonia present in the SOFC off-gas and to recover heat. The current study analysed the effects of different catalyst supports, with a focus on NO_X formation through the combustion of an SOFC off-gas surrogate. The study investigated the performance of catalysts based on the active metals, platinum and iridium, as well as the catalyst supports, Al₂O₃, SiO₂, and TiO₂. The results were correlated with catalyst characterisation data and ammonia TPD results. The investigations showed that the formation of NO_X was clearly affected by the nature of the catalyst support. The highest selectivity towards NO_X was observed for Al₂O₃, followed by SiO₂, and the lowest selectivity was observed for TiO₂. This trend was evident for the supported platinum and iridium catalysts and for the samples exclusively containing the support. The trend for N₂O formation was opposite to that of NO_X formation (TiO₂ > SiO₂ > Al₂O₃) in both the presence and absence of platinum or iridium. Full article

(This article belongs to the Special Issue NOx, VOCs (Volatile Organic Compounds) and Soot Emission Control in Catalysis, 2nd Edition)

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16 pages, 2968 KiB

Open AccessArticle

Enhanced Effect of SO₂-Induced Pt/CeZrTiO₂ on the Catalytic Oxidation of C₂H₆

by Changming Hou, Jiangliang Hu, Jiancai Hou, Dongxia Wu, Jiabao Shiliu and Weiren Bao

Catalysts 2025, 15(3), 195; https://doi.org/10.3390/catal15030195 - 20 Feb 2025

Abstract

The role of SO₂ in the catalytic oxidation of light hydrocarbons remains controversial, especially in terms of its effects on catalyst performance and reaction pathways. In this study, the Pt/CeZrTiO₂ catalyst was synthesized to explore the influence of SO₂ during [...] Read more.

The role of SO₂ in the catalytic oxidation of light hydrocarbons remains controversial, especially in terms of its effects on catalyst performance and reaction pathways. In this study, the Pt/CeZrTiO₂ catalyst was synthesized to explore the influence of SO₂ during the catalytic combustion of ethane. The results revealed two distinct roles of SO₂: (1) SO₂ interacts with the catalyst, forming new active structures that facilitate C-H bond cleavage, alter the ethane oxidation pathway, and enhance low-temperature C₂H₆ conversion. (2) SO₂ participates in the reaction process, replenishing active sites and maintaining a balance between two ethane oxidation pathways, leading to improved high-temperature C₂H₆ conversion and enhanced catalytic combustion efficiency. This study provides new insights into the role of SO₂ in modulating catalyst properties and reaction pathways for efficient light hydrocarbon combustion. Full article

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12 pages, 7922 KiB

Open AccessArticle

Modifying Pathways in CO Preferential Oxidation over Cu_xO/CeO₂ Catalysts by Boosting Cu-Ce Interfacial Interaction

by Changjin Xu, Desheng Wang, Herima Qi, Laibing Wang, Tingting Chen, Na Ta, Riqing Cheng, Huiqing Guo and Shikui Wu

Catalysts 2025, 15(2), 194; https://doi.org/10.3390/catal15020194 - 19 Feb 2025

Abstract

Improving the dispersion of Cu_xO species is critical for enhancing the catalytic performance of Cu_xO/CeO₂ catalysts in the preferential oxidation of CO. Herein, the 10Cu_xO/CeO₂ catalyst was synthesized using a combined approach of one-step thermal [...] Read more.

Improving the dispersion of Cu_xO species is critical for enhancing the catalytic performance of Cu_xO/CeO₂ catalysts in the preferential oxidation of CO. Herein, the 10Cu_xO/CeO₂ catalyst was synthesized using a combined approach of one-step thermal decomposition and precipitation methods. A series of characterization results indicate that the CeO₂ support we prepared is rich in defect sites, which not only enhance the interaction between CeO₂ and Cu_xO, but also promote the generation of more active Cu⁺ sites while reducing the strength of the Ce−O bond. Raman spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated that the weakened Ce–O bonds promote the extraction of lattice oxygen, thereby enhancing the carboxyl reaction pathway. Consequently, the highly dispersed 10Cu_xO/CeO₂ catalyst exhibits remarkably high catalytic activity for the oxidation of CO over a broad operating temperature range (i.e., CO 100% conversion, 95–215 °C). This study represents an important advancement toward the facile synthesis of highly active transition-metal oxide catalysts. Full article

(This article belongs to the Section Nanostructured Catalysts)

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15 pages, 5019 KiB

Open AccessFeature PaperArticle

Theoretical Insight into the Mechanism and Descriptor for Hydrogen Spillover on the Pt/CeO₂(111) Surface with Different Pt Coverages

by Congcong Liang, De Zhang, Xin Li, Yan Liu, Congbiao Chen, Qiang Wang, Bo Hou, Zhongyi Ma and Kangjun Wang

Catalysts 2025, 15(2), 193; https://doi.org/10.3390/catal15020193 - 19 Feb 2025

Abstract

Hydrogen spillover, as a common phenomenon, pervasively occurs in heterogeneous catalysis. Nevertheless, the understanding of the dynamic mechanism of hydrogen spillover in the typical Pt/CeO₂ system remains limited. Herein, the pathways for hydrogen spillover on the surface of two Pt/CeO₂(111) [...] Read more.

Hydrogen spillover, as a common phenomenon, pervasively occurs in heterogeneous catalysis. Nevertheless, the understanding of the dynamic mechanism of hydrogen spillover in the typical Pt/CeO₂ system remains limited. Herein, the pathways for hydrogen spillover on the surface of two Pt/CeO₂(111) models have been systematically investigated using density functional theory (DFT) calculations. Hydrogen coverage and metal coverage are considered factors influencing hydrogen spillover in the Pt/CeO₂ system. Descriptors for hydrogen migration at different metal coverages have been proposed to screen effective spillover metals within group Ⅷ: at lower metal coverages, the difference between

[E_{a d s} (M - H)]

and

[E_{a d s} (O - H)]

is considered as a descriptor, at higher metal coverages, the

[E_{a d s} (M - H)]

is used as a descriptor. Based on hydrogen spillover pathways, two dynamic mechanisms of hydrogen spillover, namely M–O–M and M–M, are introduced at different metal coverages. This study offers a deeper understanding of the hydrogen spillover phenomenon, proposes descriptors for hydrogen spillover and provides new insights into the design of heterogeneous catalysts. Full article

(This article belongs to the Section Computational Catalysis)

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18 pages, 7075 KiB

Open AccessFeature PaperArticle

Co/Mo₂C-Embedded N-Doped Carbon Nanotubes Combined with Molecularly Imprinted Membranes for Selective Electrocatalytic Determination of Imidacloprid

by Dongshi Feng, Jiangdong Dai, Yongsheng Yan and Chunxiang Li

Catalysts 2025, 15(2), 192; https://doi.org/10.3390/catal15020192 - 19 Feb 2025

Abstract

Developing a catalyst with excellent electrical conductivity and catalytic performance for on-site testing of residual imidacloprid is significant and challenging. In situ growth of Mo₂C nanodots on Co-induced N-doped carbon nanotubes (Co/Mo₂C/N-CNT) was synthesized to construct a molecularly imprinted [...] Read more.

Developing a catalyst with excellent electrical conductivity and catalytic performance for on-site testing of residual imidacloprid is significant and challenging. In situ growth of Mo₂C nanodots on Co-induced N-doped carbon nanotubes (Co/Mo₂C/N-CNT) was synthesized to construct a molecularly imprinted electrochemical sensor for the detection of imidacloprid. The results proved that the catalytic performance of Co/Mo₂C/N-CNT for imidacloprid was over two times higher than those of Co/N-CNT and commercial CNT. This improvement was attributed to the formation of a heterostructure between Co species, Mo₂C, and N-CNT, which facilitated highly exposed catalytic active sites. Additionally, the abundant Mo₂C nano-dots promoted interfacial charge transfer to achieve optimal dynamics. The optimum preparation parameters of the catalysts were obtained by response surface methodology. By analyzing the relationship between different pH values and peak potential, as well as the influence of different scanning rates on peak potential, it was deduced that the possible electrocatalytic mechanism of imidacloprid involved the reduction of the nitro group to a hydroxylamine group and H₂O. Under optimal conditions, the limit of detection (LOD) was 0.033 × 10⁻⁶ mol·L⁻¹ (R² = 0.99698), and the linear range was 0.1 × 10⁻⁶~100 × 10⁻⁶ mol·L⁻¹. The application effect of the prepared sensor was evaluated by measuring the imidacloprid in two kinds of tea, indicating that the sensor possessed good sensitivity and selectivity, and was capable of meeting the requirements of on-site detection. Full article

(This article belongs to the Special Issue Recent Advances in Carbon-Based Nanomaterial Catalysts)

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18 pages, 1234 KiB

Open AccessArticle

Palladium-Catalyzed Decarbonylative Nucleophilic Halogenation of Acid Anhydrides

by Tian Tian, Shuhei Uei, Weidan Yan and Yasushi Nishihara

Catalysts 2025, 15(2), 191; https://doi.org/10.3390/catal15020191 - 19 Feb 2025

Abstract

In this study, we developed a palladium-catalyzed decarbonylative nucleophilic halogenation reaction using inexpensive and readily available acid anhydrides as substrates. This approach effectively circumvents the instability of acyl chlorides and the low reactivity of acyl fluorides. The Pd/Xantphos catalyst system exhibited excellent compatibility [...] Read more.

In this study, we developed a palladium-catalyzed decarbonylative nucleophilic halogenation reaction using inexpensive and readily available acid anhydrides as substrates. This approach effectively circumvents the instability of acyl chlorides and the low reactivity of acyl fluorides. The Pd/Xantphos catalyst system exhibited excellent compatibility with the thermodynamically and kinetically challenging reductive elimination of C–X bonds (X = I, Br, and Cl) from Pd(II) intermediates. Notably, for electron-donating substrates, adopting an open system significantly improved the reaction efficiency. The positive effect of the open system may be due to the reversible nature of CO insertion and deinsertion, which helps direct the reaction toward the desired pathway by allowing the generated CO to exit the reaction system. Mechanistic studies suggest that the reaction proceeds through a highly reactive acyl halide intermediate, followed by a unimolecular fragment coupling (UFC) pathway via decarbonylation or an alternative pathway involving the formation of an activated anionic palladate complex in the presence of lithium halide. Full article

(This article belongs to the Special Issue Recent Advances in Palladium-Catalyzed Organic Synthesis)

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20 pages, 3151 KiB

Open AccessFeature PaperArticle

Environmental Impacts on the Photocatalytic Activities of Anatase and Rutile

by Karolina Solymos, Áron Ágoston, Tamás Gyulavári, Lilla Szalma, Milica Todea, Ákos Kukovecz, Zoltán Kónya and Zsolt Pap

Catalysts 2025, 15(2), 190; https://doi.org/10.3390/catal15020190 - 18 Feb 2025

Abstract

Titanium dioxide (TiO₂) nanoparticles (NPs) are widely used in various industries and are increasingly found in environmental systems, especially in soil. However, the environmental behavior of TiO₂ NPs is still poorly understood. Hence, this study aims to fill this gap [...] Read more.

Titanium dioxide (TiO₂) nanoparticles (NPs) are widely used in various industries and are increasingly found in environmental systems, especially in soil. However, the environmental behavior of TiO₂ NPs is still poorly understood. Hence, this study aims to fill this gap by investigating the short- and long-term effects of soil solutions on anatase and rutile NPs. The experiments were carried out using two soil types, which have very different chemical properties, in order to obtain a more nuanced picture of how these factors affect the stability, surface chemistry, and photocatalytic activity of TiO₂ NPs. The results indicate that acidic soil solutions with lower ionic strength tend to enhance the stability of TiO₂ NPs by preventing aggregation, while alkaline solutions with higher ionic strength promote aggregation and reduce photocatalytic activity by blocking active sites. Additionally, the adsorption of organic matter and other soil components on the nanoparticle surface further complicates their behavior, potentially reducing their photocatalytic efficiency. The interaction time plays a crucial role in determining the long-term fate of TiO₂ NPs in soil environments. Extended exposure to soil solutions leads to changes in crystallite size, surface charge, and the adsorption of functional groups, which, in turn, affect the NPs’ photocatalytic properties. Full article

(This article belongs to the Special Issue Photocatalysis: Past, Present, and Future Outlook)

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17 pages, 6174 KiB

Open AccessFeature PaperArticle

Enhancing H₂O₂ Generation Using Activated Carbon Electrocatalyst Cathode: Experimental and Computational Insights on Current, Cathode Design, and Reactor Configuration

by Maria del Mar Cerrillo-Gonzalez, Amir Taqieddin, Stephanie Sarrouf, Nima Sakhaee, Juan Manuel Paz-García, Akram N. Alshawabkeh and Muhammad Fahad Ehsan

Catalysts 2025, 15(2), 189; https://doi.org/10.3390/catal15020189 - 18 Feb 2025

Abstract

Granular activated carbon (GAC) serves as a cost-efficient electrocatalyst cathode in electrochemical water treatment. This study investigates the impact of current intensity and cathode mesh size on the electrocatalytic generation of reactive oxygen species (ROS), i.e., hydrogen peroxide (H₂O₂) [...] Read more.

Granular activated carbon (GAC) serves as a cost-efficient electrocatalyst cathode in electrochemical water treatment. This study investigates the impact of current intensity and cathode mesh size on the electrocatalytic generation of reactive oxygen species (ROS), i.e., hydrogen peroxide (H₂O₂) and hydroxyl radicals (•OH), for removing p-nitrophenol (PNP) as a representative contaminant. The findings suggest that these parameters exert a factorial effect on PNP removal, which is statistically endorsed via the analysis of variance. The −20 + 40 mesh GAC exhibited superior electrocatalytic performance due to its optimal balance of porosity and active surface area. Additionally, the reactor configuration was also studied. Employing two reactors in series configuration resulted in a 23% increase in H₂O₂ generation and a 32% enhancement in overall PNP removal compared with the single reactor configuration. This enhancement is attributed to (i) the enhanced electroactive area, (ii) the greater retention time of PNP over the electrocatalyst surface, and (iii) the increased dissolved oxygen and H₂O₂ content in the second reactor, promoting the overall H₂O₂ generation. Numerical simulations were conducted to compute H₂O₂ concentration profiles, providing a detailed representation of the physical, chemical, and electrochemical processes. The model exhibited a high degree of accuracy compared with the experimental measurements, with R² values ranging from ~0.76 to 0.99 and MAE values between ~0.04 and 0.23 mg/L. The simulation results highlight a strong interplay between H₂O₂ generation, its reaction kinetics during PNP removal, and electrode utilization efficiency. These findings emphasize the importance of optimizing the applied current magnitude and reactor operation duration to maximize electrode efficiency and H₂O₂ generation and utilization, while minimizing electrochemical bubble blockage. Overall, this study provides fundamental insights to optimize the electroactive area for enhanced ROS generation toward efficient contaminant removal, supporting sustainable groundwater remediation technologies in the face of emerging pollutants. Full article

(This article belongs to the Special Issue Electrocatalytic Wastewater Treatment: Resource Utilization and New Technology)

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