Catalysts

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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15 pages, 2302 KiB

Open AccessArticle

Zeolitized Clays and Their Use for the Capture and Photo-Fenton Degradation of Methylene Blue

by Koffi Simeon Kouadio, Ekou Tchirioua and Jérémy Dhainaut

Catalysts 2025, 15(2), 188; https://doi.org/10.3390/catal15020188 - 18 Feb 2025

Abstract

Water pollution by dyes is a major environmental problem, particularly in the textile, food, and pharmaceutical industries. These dyes are often complex chemical compounds that are difficult to remediate due to their chemical stability, their solubility in water, and their resistance to conventional [...] Read more.

Water pollution by dyes is a major environmental problem, particularly in the textile, food, and pharmaceutical industries. These dyes are often complex chemical compounds that are difficult to remediate due to their chemical stability, their solubility in water, and their resistance to conventional treatment processes such as filtration, coagulation, or decantation. Thus, to date, there is still a need to make water treatment processes more performant and cost-efficient. The main aim of this research is to prepare photocatalytically active MFI-type zeolites from natural clays and support iron oxide nanoparticles. These catalysts were characterized and evaluated for the capture and the photo-Fenton degradation of methylene blue (MB) in aqueous solution. After 10 min under photo-Fenton conditions, Fe/MTK-MFI presented almost complete removal of MB for up to four consecutive cycles. Full article

(This article belongs to the Special Issue Porous Catalysts: Synthesis and Catalytic Performance)

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15 pages, 1579 KiB

Open AccessReview

Influence of Surfactants on Interfacial Microbial Degradation of Hydrophobic Organic Compounds

by Shuting Zhu, Meishu Li, Tengze Qian, Juanjuan Chen and Tao Pan

Catalysts 2025, 15(2), 187; https://doi.org/10.3390/catal15020187 - 18 Feb 2025

Abstract

This review explores the role of surfactants in enhancing or inhibiting the biodegradation of hydrophobic organic compounds (HOCs) by microorganisms. Bioavailability, the extent to which pollutants can be accessed and metabolized by microbes, is a key factor in determining degradation efficiency. Hydrophobic organic [...] Read more.

This review explores the role of surfactants in enhancing or inhibiting the biodegradation of hydrophobic organic compounds (HOCs) by microorganisms. Bioavailability, the extent to which pollutants can be accessed and metabolized by microbes, is a key factor in determining degradation efficiency. Hydrophobic organic compounds, like polycyclic aromatic hydrocarbons, have limited bioavailability due to their low aqueous solubility, hindering microbial uptake. Microorganisms utilize strategies such as biofilm formation and direct adhesion to hydrophobic surfaces to overcome this limitation. Surfactants, both synthetic and biosurfactants, have been explored to improve HOC bioavailability by increasing solubility through micelles or emulsions. However, surfactants can also affect microbial adhesion by altering cell surface properties, leading to mixed results in degradation efficiency. Biosurfactants, which are more environmentally friendly, show promise in enhancing biodegradation without the toxic effects of synthetic surfactants. The review highlights the complex interactions between surfactants, microbial adhesion, and HOC biodegradation, emphasizing the need for tailored surfactant formulations to optimize bioremediation. Future research should focus on balancing the surfactant concentration and microbial surface properties to enhance biodegradation in contaminated environments. Full article

(This article belongs to the Special Issue Microbial Biocatalysis, 2nd Edition)

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11 pages, 1618 KiB

Open AccessArticle

Synthesis of Novel s-Indacene-1,5-dione and Isoxazole Derivatives via NaNO₂-Catalyzed/Involved Transformation of Cyclopentenone-MBH Acetates

by Na Li, Xiao-Tian Mo, Min Li, Yi-Na Ma and Lin Jiang

Catalysts 2025, 15(2), 186; https://doi.org/10.3390/catal15020186 - 17 Feb 2025

Abstract

A rapid synthesis of structurally novel s-indacene-1,5-dione and cyclopentanone-fused isoxazole derivatives in generally moderate yields was achieved through the NaNO₂-catalyzed/involved transformation of cyclopentenone-MBH acetates. Under similar reaction conditions, two different reaction pathways were observed depending on the type of aryl [...] Read more.

A rapid synthesis of structurally novel s-indacene-1,5-dione and cyclopentanone-fused isoxazole derivatives in generally moderate yields was achieved through the NaNO₂-catalyzed/involved transformation of cyclopentenone-MBH acetates. Under similar reaction conditions, two different reaction pathways were observed depending on the type of aryl substituent on MBH acetates. In the formation of s-indacene-1,5-diones, NaNO₂ is proposed to act as a nucleophilic catalyst to initiate the stepwise dimeric cyclization/oxidative aromatization, whereas in the formation of isoxazole derivatives, it plays the role of nucleophilic reagent of (3+2) cycloaddition. Using NaNO₂ as an inexpensive and readily available catalyst or reaction component, mild reaction conditions, operational simplicity, and metal-free transition are the main advantages of this work. Full article

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

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19 pages, 10816 KiB

Open AccessArticle

Self-Assembly of Benzyloxycarbonyl Histidine with Zinc Ions for the Construction of Esterase Mimics

by Jiacheng Sun, Jingjing Guo, Ling Liu, Yu Liu, Linling Yu and Yan Sun

Catalysts 2025, 15(2), 185; https://doi.org/10.3390/catal15020185 - 17 Feb 2025

Abstract

Esterases have been applied in many industrial fields. However, many esterases have inherent defects as natural enzyme, such as low long-term storability, poor operational stability, and difficulty in recovery for reuse. Herein, two histidine derivatives with different structures, L-benzyloxycarbonyl histidine (Z-L-His) and D-benzyloxycarbonyl [...] Read more.

Esterases have been applied in many industrial fields. However, many esterases have inherent defects as natural enzyme, such as low long-term storability, poor operational stability, and difficulty in recovery for reuse. Herein, two histidine derivatives with different structures, L-benzyloxycarbonyl histidine (Z-L-His) and D-benzyloxycarbonyl histidine (Z-D-His), were used to self-assemble with zinc ions to construct esterase mimics (Z-L-His/Zn²⁺ and Z-D-His/Zn²⁺) based on a minimalist strategy. Two natural enzymes were used for comparison. It was found that the Z-His structure influenced only the stereoselectivity of the enzyme mimic. The kinetics of Z-L-His/Zn²⁺ followed the classical Michaelis–Menten equation, and its catalytic efficiency was comparable to that of natural enzymes. It was verified that Z-L-His/Zn²⁺ had good catalytic stability over a wide range of pH, organic solvent concentrations, ionic strengths, and incubation temperatures. Z-L-His/Zn²⁺ retained high activity after incubation in different environments for 7 d, demonstrating excellent long-term storage stability. Moreover, Z-L-His/Zn²⁺ exhibited good reusability, retaining 93% of its original activity after six cycles, proving its potential for industrial applications in mimicking esterase. Full article

(This article belongs to the Special Issue New Trends in Industrial Biocatalysis, 2nd Edition)

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13 pages, 4196 KiB

Open AccessArticle

Enhanced Photocatalytic CO₂ Reduction via CCH/g-C₃N₄ Heterojunction: Optimizing Charge Carrier Dynamics and Visible-Light Utilization

by Xinpeng Mo, Hong Zhong, Chenhuan Hu, Haoxiong Jin, Xianfeng Liu, Huanhuan Liu and Genqiang Zhang

Catalysts 2025, 15(2), 184; https://doi.org/10.3390/catal15020184 - 17 Feb 2025

Abstract

The photocatalytic CO₂ reduction (PCR) into value-added fuels offers a promising solution to energy shortages and the greenhouse effect, thanks to the mild conditions and environmental sustainability. However, the activation of CO₂ is challenging because of the thermodynamic stability and chemical [...] Read more.

The photocatalytic CO₂ reduction (PCR) into value-added fuels offers a promising solution to energy shortages and the greenhouse effect, thanks to the mild conditions and environmental sustainability. However, the activation of CO₂ is challenging because of the thermodynamic stability and chemical inertness of CO₂ molecules, which significantly restricts the efficiency of PCR. Cobalt carbonate hexahydrate (CCH), known for its excellent CO₂ adsorption and activation properties, faces challenges like poor electron–hole separation and photoresponse. To address these issues, graphitic carbon nitride (CN) as a “pseudo-sensitizer” was introduced into the system by an in situ heterojunction synthesis strategy to produce CCH/CN photocatalyst, where Co–N bonds formed between CCH and CN enhance charge carrier migration and lower interfacial resistance. The CCH/CN catalyst achieved a CO production rate of 19.65 μmol g⁻¹ h⁻¹, outperforming CCH, CN, and a mechanically mixed sample (Mix) by 7.74, 2.31, and 1.77 times, respectively. This work demonstrates an effective strategy for designing heterojunction catalysts to improve visible light utilization and charge transfer for efficient CO₂ reduction. Full article

(This article belongs to the Special Issue Photocatalysts for CO₂ Reduction)

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33 pages, 3179 KiB

Open AccessReview

H₂O₂ and HAN Green Monopropellants—A State-of-the-Art Review on Their Recent Development, Corresponding Synthesized Catalysts, and Their Possible Use as Thrusters

by Youssef Kasbi, Imane Remissa, Kainaubek Toshtay, Assia Mabrouk, Ahmed Bachar, Seitkhan Azat, Ahmed E. S. Nosseir, Amit Tiwari, El Mouloudi Sabbar and Rachid Amrousse

Catalysts 2025, 15(2), 183; https://doi.org/10.3390/catal15020183 - 16 Feb 2025

Abstract

This review provides a state-of-the-art and up-to-date analysis of the design and development of green monopropellant thrusters based on hydrogen peroxide (H₂O₂) and hydroxyl ammonium nitrate (HAN) as high-energy compounds for reaction control maneuvering of satellites. In summary, we [...] Read more.

This review provides a state-of-the-art and up-to-date analysis of the design and development of green monopropellant thrusters based on hydrogen peroxide (H₂O₂) and hydroxyl ammonium nitrate (HAN) as high-energy compounds for reaction control maneuvering of satellites. In summary, we introduce the new concept of Green Liquid Propellants (GLPs) that can serve as eco-friendly alternatives to conventional hydrazine thrusters. GLPs offer several advantages, including low toxicity, acceptable thermal decomposition and combustion behaviors, low onset temperatures of decomposition, stability, and long-term storability, compared to hydrazine. H₂O₂ exhibits a low onset temperature; however, its storability does not match that of hydrazine. On the other hand, HAN boasts excellent storability; however, it comes with a higher onset temperature when compared to hydrazine. This review provides critical insights into the recent advancements in H₂O₂ and HAN thrusters, along with an examination of the corresponding catalysts. The focus is on their application for the long-term maneuvering of satellites. We have chosen H₂O₂ and HAN formulations to focus on these two GLPs due to their extensive use by various space agencies worldwide. Moreover, the future directives of both selected green propellants were discussed for potential applications. Finally, the choice between H₂O₂ and HAN depends on the specific requirements of the propulsion system, taking into account factors such as performance, environmental impact, safety, and operational considerations. Each propellant has its advantages and challenges, and ongoing research aims to address some of the limitations associated with these green propellants. Full article

(This article belongs to the Section Catalysis for Sustainable Energy)

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17 pages, 5656 KiB

Open AccessArticle

CdS Quantum Dot Encapsulated in Anatase/Silica Core–Shell Nanostructures: A Synergistic Approach for Efficient Photocatalytic Water Purification

by Adil Alshoaibi, Shumaila Islam and Kawther Alamer

Catalysts 2025, 15(2), 182; https://doi.org/10.3390/catal15020182 - 14 Feb 2025

Abstract

A mesoporous anatase/silica core–shell nanostructure (ASCS) was synthesized via a sol–gel method at 90 °C, and then cadmium sulfide quantum dots (CdS-QDs) were encapsulated in it, forming CdS-ASCS. The CdS-ASCS was synthesized to enhance the efficiency of heterogeneous nanophotocatalysts. The CdS-ASCS nanoparticles exhibited [...] Read more.

A mesoporous anatase/silica core–shell nanostructure (ASCS) was synthesized via a sol–gel method at 90 °C, and then cadmium sulfide quantum dots (CdS-QDs) were encapsulated in it, forming CdS-ASCS. The CdS-ASCS was synthesized to enhance the efficiency of heterogeneous nanophotocatalysts. The CdS-ASCS nanoparticles exhibited a core–shell morphology with a particle size of approximately 1.8 nm and a shell thickness of about 8 nm. The uniform distribution of cadmium, sulfur, titanium, and silicon was observed, along with a pore radius of roughly 2.5 nm and a bandgap energy of approximately 3.2 eV. Under ultraviolet irradiation, the CdS-ASCS demonstrated a photocatalytic degradation of 91% for methylene blue (MB) within 240 min, with a rate constant of 0.01 min⁻¹. These findings suggested that CdS-ASCS is a highly effective photocatalyst with promising applications in water purification. Full article

(This article belongs to the Section Photocatalysis)

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45 pages, 7981 KiB

Open AccessFeature PaperReview

Emerging Trends in Palladium Nanoparticles: Sustainable Approaches for Enhanced Cross-Coupling Catalysis

by Jude I. Ayogu, Numair Elahi and Constantinos D. Zeinalipour-Yazdi

Catalysts 2025, 15(2), 181; https://doi.org/10.3390/catal15020181 - 14 Feb 2025

Abstract

Palladium nanoparticles (PdNPs) are transforming the landscape of modern catalysis and offer sustainable and efficient alternatives to traditional catalysts for cross-coupling reactions. Owing to their exceptional surface area-to-volume ratio, PdNPs exhibit superior catalytic activity, selectivity, and recyclability, making them ideal for greener chemical [...] Read more.

Palladium nanoparticles (PdNPs) are transforming the landscape of modern catalysis and offer sustainable and efficient alternatives to traditional catalysts for cross-coupling reactions. Owing to their exceptional surface area-to-volume ratio, PdNPs exhibit superior catalytic activity, selectivity, and recyclability, making them ideal for greener chemical processes. Recent innovations have focused on improving the stability and reusability of PdNPs through environmentally benign approaches, such as water-based reactions, renewable stabilizers, and magnetic nanoparticle supports. Advances in catalyst design, including PdNP immobilization on magnetic nanosilica for enhanced recyclability in Suzuki–Miyaura reactions, nitrogen-doped carbon nanosheets achieving up to ninefold improvements in turnover frequencies, and biodegradable biopolymer matrices that reduce environmental impact, have effectively addressed key challenges such as catalyst leaching, support degradation, and agglomeration. The shift from conventional catalysis to these cutting-edge nanocatalytic techniques signifies a critical movement toward sustainable chemistry, positioning PdNPs at the forefront of industrial applications and the future of eco-friendly chemical synthesis. Full article

(This article belongs to the Special Issue Palladium Catalysis)

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20 pages, 4626 KiB

Open AccessFeature PaperArticle

Enzymatic Oxidation of Hydroxytyrosol in Deep Eutectic Solvents for Chitosan Functionalization and Preparation of Bioactive Nanogels

by Myrto G. Bellou, Anastasia Skonta, Alexandra V. Chatzikonstantinou, Angeliki C. Polydera, Petros Katapodis, Epaminondas Voutsas and Haralambos Stamatis

Catalysts 2025, 15(2), 180; https://doi.org/10.3390/catal15020180 - 14 Feb 2025

Abstract

Biocatalytic processes for the formation of bioactive compounds and biopolymer preparations that can be applied in pharmaceuticals and cosmetics are gaining increasing interest due to their safety and sustainability, relying on environmentally friendly approaches and biocompatible compounds. In this work, we investigate the [...] Read more.

Biocatalytic processes for the formation of bioactive compounds and biopolymer preparations that can be applied in pharmaceuticals and cosmetics are gaining increasing interest due to their safety and sustainability, relying on environmentally friendly approaches and biocompatible compounds. In this work, we investigate the implementation of various Deep Eutectic Solvents (DES) in the laccase-catalyzed oxidation of hydroxytyrosol (HT), aiming to produce its oligomer derivatives such as HT dimer and trimer. The composition of the reaction mixture in which the oligomers’ yield was the highest was 70% v/v Bet:PG (1:4 molar ratio). The oligomers formed were subsequently used for the non-enzymatic grafting of chitosan (CS) and the development of bioactive chitosan-based nanogels (NG). Grafted chitosan nanogels were prepared by ionic gelation using sodium tripolyphosphate (TPP) as a cross-linking agent. The functionalized chitosan was characterized using Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy, while Scanning Electron Microscopy (SEM) was employed for nanogel characterization. Compared to unmodified chitosan nanogels, grafted chitosan nanogels exhibited almost ten-fold higher antioxidant activity and approximately 20% greater antibacterial activity. Full article

(This article belongs to the Special Issue Catalytic Procedures for the Synthesis of Pharmaceutical Active Compounds in Deep Eutectic Solvents)

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8 pages, 942 KiB

Open AccessCommunication

Highly Effective Asymmetric Henry Reaction Catalyzed by Chiral Complex of Cu (II)-Aziridine-Functionalized Organophosphorus Compounds

by Michał Rachwalski, Julia Wojtaszek, Julia Szymańska and Adam M. Pieczonka

Catalysts 2025, 15(2), 179; https://doi.org/10.3390/catal15020179 - 14 Feb 2025

Abstract

A synthesis of organophosphorus compounds containing an aziridine ring, previously described by our group, has been performed and the catalytic activity of the aforementioned chiral heterorganic compounds has been investigated in the asymmetric nitroaldol (Henry) reaction between aromatic/aliphatic aldehydes and nitromethane in the [...] Read more.

A synthesis of organophosphorus compounds containing an aziridine ring, previously described by our group, has been performed and the catalytic activity of the aforementioned chiral heterorganic compounds has been investigated in the asymmetric nitroaldol (Henry) reaction between aromatic/aliphatic aldehydes and nitromethane in the presence of catalytic amounts of copper (II) acetate. In several cases, the chiral β-nitroalcohols have been obtained with high chemical yields and exhibited very high enantiomeric excess values (over 95%). Notably, the use of two enantiomerically pure catalysts, differing in the absolute configuration of the aziridine unit, resulted in the formation of two enantiomeric products of the Henry reaction. Full article

(This article belongs to the Special Issue Catalysis in Heterocyclic and Organometallic Synthesis, 3rd Edition)

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22 pages, 8049 KiB

Open AccessReview

A Review on the Design of Cathode Catalyst Materials for Zinc-Iodine Batteries

by Wanyi Cui, Weishang Jia, Bailin Yu, Shirui Wang, Xiaoyuan Zhang, Xiaolong Qubie, Xingbin Lv and Feifei Wang

Catalysts 2025, 15(2), 178; https://doi.org/10.3390/catal15020178 - 13 Feb 2025

Abstract

Zinc-iodine batteries, which have the advantages of low cost, high safety, long lifespan, and high energy density, currently rank as one of the most promising electrical energy storage devices. However, these batteries still face significant challenges, including sluggish iodine redox kinetics and the [...] Read more.

Zinc-iodine batteries, which have the advantages of low cost, high safety, long lifespan, and high energy density, currently rank as one of the most promising electrical energy storage devices. However, these batteries still face significant challenges, including sluggish iodine redox kinetics and the shuttle effect of polyiodides. This article provides a comprehensive review of recent advancements in cathode catalysts for zinc-iodine batteries, with a particular focus on the electrochemical processes and working mechanisms of catalysts, and delves into the prospects and scientific issues associated with their development. It then presents a detailed analysis of the mechanisms, principles, and performances of various catalysts, including heteroatom-doped carbon materials, single-atom catalysts, dual-atom catalysts, molecular catalysts, and transition metal compounds, in catalyzing the cathodes of zinc-iodine batteries. These diverse catalysts, with their unique functionalities and catalytic effects, can substantially address the kinetic challenges related to iodine conversion efficiency and the stability issues associated with polyiodide shuttle. Nonetheless, several challenges persist, such as reducing the synthesis cost of catalysts, minimizing catalyst usage to enhance the overall energy density of zinc-iodine batteries, and improving the long-term activity of catalysts. This review is expected to deepen our understanding of cathode catalysts for zinc-iodine batteries and facilitate their practical applications in the future. Full article

(This article belongs to the Special Issue Powering the Future: Advances of Catalysis in Batteries)

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11 pages, 1066 KiB

Open AccessArticle

Photoelectrochemical Behavior of CuWO₄ in Tandem System with CuBi₂O₄

by Anna A. Murashkina, Aida V. Rudakova, Tair V. Bakiev, Alexei V. Emeline and Detlef W. Bahnemann

Catalysts 2025, 15(2), 177; https://doi.org/10.3390/catal15020177 - 13 Feb 2025

Abstract

In this study, we explore the charge transfer mechanism between CuWO₄ and CuBi₂O₄ in a tandem photoelectrochemical cell. Physical–chemical characterization of the individual between CuWO₄ and CuBi₂O₄ electrodes electrode by XRD, XPS, and SEM methods [...] Read more.

In this study, we explore the charge transfer mechanism between CuWO₄ and CuBi₂O₄ in a tandem photoelectrochemical cell. Physical–chemical characterization of the individual between CuWO₄ and CuBi₂O₄ electrodes electrode by XRD, XPS, and SEM methods confirm the successful formation of the target systems. Based on XPS and DRS data, the electronic band edge positions were estimated (valence bands: −6.1 eV and −5.6 eV; conduction bands: −3.7 eV and −3.8 eV for CuWO₄ and CuBi₂O₄, respectively), indicating that both type II and Z-scheme charge transfer mechanisms are possible in the system. The results of photoelectrochemical studies infers that, in a CuWO₄||CuBi₂O₄ tandem photoelectrochemical cell, the major mechanism of the charge transfer between CuWO₄ and CuBi₂O₄ is a realization of Z-scheme through an external circuit. Full article

(This article belongs to the Special Issue Commemorative Special Issue for Prof. Dr. David Ollis)

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14 pages, 10847 KiB

Open AccessFeature PaperArticle

Promoting Effect of Copper Doping on LaMO₃ (M = Mn, Fe, Co, Ni) Perovskite-Supported Gold Catalysts for Selective Gas-Phase Ethanol Oxidation

by Lijun Yue, Jie Wang and Peng Liu

Catalysts 2025, 15(2), 176; https://doi.org/10.3390/catal15020176 - 13 Feb 2025

Abstract

Developing more effective gold–support synergy is essential for enhancing the catalytic performance of supported gold nanoparticles (AuNPs) in the gas-phase oxidation of ethanol to acetaldehyde (AC) at lower temperatures. This study demonstrates a significantly improved Au–support synergy achieved by copper doping in LaMO [...] Read more.

Developing more effective gold–support synergy is essential for enhancing the catalytic performance of supported gold nanoparticles (AuNPs) in the gas-phase oxidation of ethanol to acetaldehyde (AC) at lower temperatures. This study demonstrates a significantly improved Au–support synergy achieved by copper doping in LaMO₃ (M = Mn, Fe, Co, Ni) perovskites. Among the various Au/LaMCuO₃ catalysts, Au/LaMnCuO₃ exhibited exceptional catalytic activity, achieving an AC yield of up to 91% and the highest space-time yield of 764 g_AC g_Au⁻¹ h⁻¹ at 225 °C. Notably, this catalyst showed excellent hydrothermal stability, maintaining performance for at least 100 h without significant deactivation when fed with 50% aqueous ethanol. Comprehensive characterization reveals that Cu doping facilitates the formation of surface oxygen vacancies on the Au/LaMCuO₃ catalysts and enhances Au–support interactions. The LaMnCuO₃ perovskite stabilizes the crucial Cu⁺ species, resulting in a stable Au-Mn-Cu synergy within the Au/LaMnCuO₃ catalyst, which facilitates the activation of O₂ and ethanol at lower temperatures. The optimization of the reaction conditions further improves AC productivity. Kinetic studies indicate that the cleavages of both the O-H bond and the α-C-H bond of ethanol are the rate-controlling steps. Full article

(This article belongs to the Special Issue New Insights into Synergistic Dual Catalysis)

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20 pages, 6732 KiB

Open AccessArticle

Preparation of Recyclable Magnetic Catalyst (Pd/PDA@Fe₃O₄) and the Catalytic Degradation of 4-Nitrophenol and Rhodamine B

by Wei Wang, Jiaqi Liu, Guang Shi, Shiqi Wu, Shihan Zhang and Ruixia Yuan

Catalysts 2025, 15(2), 175; https://doi.org/10.3390/catal15020175 - 13 Feb 2025

Abstract

A magnetic shell-structured nano-catalyst was prepared by self-polymerization of dopamine wrapped by ferric oxide as the carrier, which was loaded with palladium nanoparticles (Pd/PDA@Fe₃O₄). The presence of magnetic Fe₃O₄ made it easy for nanoscale palladium particles [...] Read more.

A magnetic shell-structured nano-catalyst was prepared by self-polymerization of dopamine wrapped by ferric oxide as the carrier, which was loaded with palladium nanoparticles (Pd/PDA@Fe₃O₄). The presence of magnetic Fe₃O₄ made it easy for nanoscale palladium particles to recover and prevent the loss of palladium nanoparticles that is unavoidable in traditional usage and preparation procedures. The catalyst was characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy, thermal weight loss analysis, Raman spectroscopy, X-ray photo-electron spectroscopy, and magnetic properties analysis. The catalytic performance of the prepared catalyst was investigated taking 4-nitrophenol (10 mg/L) and rhodamine B (15 mg/L) as the target pollutants. The results showed that under the conditions of 35 °C, pH = 7 and a catalyst dosage of 3 mg, the catalytic reduction efficiency of 4-nitrophenol, rhodamine B, and the mixture of them all can reach 99%. The catalytic efficiency of Pd/PDA@Fe₃O₄ remained above 90% after being used 10 times. The shell structure of Fe₃O₄ made it possible and easy to recover and recycle the nanoscale palladium, which was a real problem in the usage of nano-catalysts. At the same time, the problem of separation and recovery of palladium nano-catalyst is solved by magnetism, which provides research ideas for the recycling and utilization of nano-materials. Full article

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28 pages, 1545 KiB

Open AccessReview

Zeolite-Supported TiO₂ for Enhanced Photocatalytic Performance in Environmental Applications: A Review

by Sanja J. Armaković and Stevan Armaković

Catalysts 2025, 15(2), 174; https://doi.org/10.3390/catal15020174 - 13 Feb 2025

Abstract

The combination of TiO₂ with zeolites has emerged as a transformative strategy to enhance photocatalytic performance for environmental applications. The combination of zeolites’ regular pore structure, high surface area, and adsorption capacity with the photocatalytic properties of TiO₂ allows synergistic effects, [...] Read more.

The combination of TiO₂ with zeolites has emerged as a transformative strategy to enhance photocatalytic performance for environmental applications. The combination of zeolites’ regular pore structure, high surface area, and adsorption capacity with the photocatalytic properties of TiO₂ allows synergistic effects, significantly improving the removal of organic pollutants and hazardous substances from water. This review provides a comprehensive analysis of TiO₂–zeolite composites, focusing on their synthesis, structural characteristics, and photocatalytic mechanisms. Advances in the characterization of material and computational analysis are applied to explain the relationship between structure and catalytic activity. Environmental applications such as water purification and renewable energy production are critically evaluated, highlighting their potential for addressing pressing global challenges. The review also addresses key challenges, including material stability, scalability of synthesis methods, and cost-effectiveness, while presenting future perspectives for the development and application of TiO₂–zeolite composites in sustainable catalysis. Full article

(This article belongs to the Special Issue Catalysis on Zeolites and Zeolite-Like Materials, 3rd Edition)

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20 pages, 4800 KiB

Open AccessArticle

Photodegradation of Emerging Pollutants Using a Quaternary Mixed Oxide Catalyst Derived from Its Corresponding Hydrotalcite

by L. V. Castro, B. Alcántar-Vázquez, M. E. Manríquez, E. Albiter and E. Ortiz-Islas

Catalysts 2025, 15(2), 173; https://doi.org/10.3390/catal15020173 - 13 Feb 2025

Abstract

This study aimed to synthesize a multicationic hydrotalcite and transform it into mixed oxide nanostructures (ZnO/TiO₂/CeO₂/Al₂O₃, referred to as MixO) to serve as a heterogeneous photocatalyst for degrading various pollutants, including methylene blue (MB), methyl [...] Read more.

This study aimed to synthesize a multicationic hydrotalcite and transform it into mixed oxide nanostructures (ZnO/TiO₂/CeO₂/Al₂O₃, referred to as MixO) to serve as a heterogeneous photocatalyst for degrading various pollutants, including methylene blue (MB), methyl orange (MO), paracetamol (PA), and paraquat (PQ). The hydrotalcite was synthesized via an ultrasound-assisted method and calcined at 700 °C to obtain the corresponding mixed metal oxide. A comprehensive characterization of both the multicationic hydrotalcite (MC-LDH) and the mixed metal oxides (MixO) was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and pH_PZC analysis. The MixO sample exhibited an optical bandgap of 3.19 eV. Photocatalytic performance was evaluated during 240 min of UV irradiation, demonstrating high degradation efficiencies attributable to the synergistic interactions among ZnO, TiO₂, and CeO₂. Degradation efficiencies reached 99.3% for MO and 95.2% for MB, while PA and PQ showed moderate degradation rates of 60% and 15%, respectively. The degradation kinetics of all pollutant compounds followed the Langmuir–Hinshelwood model. Additionally, the MixO catalyst maintained consistent performance over four consecutive degradation cycles, highlighting its reusability and stability. These findings underscore the potential of MixO mixed oxide nanostructures as practical and recyclable photocatalysts for environmental remediation, particularly in wastewater treatment applications. Full article

(This article belongs to the Special Issue Advances in Photocatalytic Degradation)

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24 pages, 3072 KiB

Open AccessFeature PaperReview

Recent Advances in Membrane Electrode Assembly Based Nitrate Reduction Electrolyzers for Sustainable Ammonia Synthesis

by Keon-Han Kim and Jeonghoon Lim

Catalysts 2025, 15(2), 172; https://doi.org/10.3390/catal15020172 - 12 Feb 2025

Abstract

The electrochemical reduction from nitrate (NO₃RR) to ammonia (NH₃) provides a decentralized and environmentally friendly route for sustainable ammonia production while addressing the urgent issue of nitrate pollution in water bodies. Recent advancements in NO₃RR research have [...] Read more.

The electrochemical reduction from nitrate (NO₃RR) to ammonia (NH₃) provides a decentralized and environmentally friendly route for sustainable ammonia production while addressing the urgent issue of nitrate pollution in water bodies. Recent advancements in NO₃RR research have improved catalyst designs, mechanistic understanding, and electrolyzer technologies, enhancing selectivity, yield, and energy efficiency. This review explores cutting-edge developments, focusing on innovative designs for catalysts and electrolyzers, such as membrane electrode assemblies (MEA) and electrolyzer configurations, understanding the role of membranes in MEA designs, and various types of hybrid and membrane-free reactors. Furthermore, the integration of NO₃RR with anodic oxidation reactions has been demonstrated to improve overall efficiency by generating valuable co-products. However, challenges such as competitive hydrogen evolution, catalyst degradation, and scalability remain critical barriers to large-scale adoption. We provide a comprehensive overview of recent progress, evaluate current limitations, and identify future research directions for realizing the full potential of NO₃RR in sustainable nitrogen cycling and ammonia synthesis. Full article

(This article belongs to the Special Issue Electrocatalytic Nitrogen-Cycle)

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17 pages, 4382 KiB

Open AccessArticle

The Effect of the Pore Size of TiO₂ Aerogel on the Photocatalytic Decomposition of Formaldehyde

by Fenglei Sun, Xian Yue, Xianbo Yu, Yuqian Di, Hu Chen, Shuao Xie, Wei Han, Xiaoxue Xi, Wenjing Zhang, Hanyu Zou, Huaxin Li and Junhui Xiang

Catalysts 2025, 15(2), 171; https://doi.org/10.3390/catal15020171 - 12 Feb 2025

Abstract

TiO₂ aerogels have been employed for the degradation of formaldehyde (HCHO) via the photocatalytic generation of reactive oxygen species (ROS) (O²⁻, ·OH), and its pore size plays a crucial role in affecting the decomposition efficiency. However, there remains a lack [...] Read more.

TiO₂ aerogels have been employed for the degradation of formaldehyde (HCHO) via the photocatalytic generation of reactive oxygen species (ROS) (O²⁻, ·OH), and its pore size plays a crucial role in affecting the decomposition efficiency. However, there remains a lack of a comprehensive understanding regarding the internal mechanisms underlying the influence of pore size on HCHO decomposition. In this study, we prepared TiO₂ aerogels by the sol–gel method, and added polyvinyl alcohol (PVA) to introduce flexible molecular chains for pore size regulation, and obtained anatase crystals after a heat treatment at 800 °C. The photocatalytic decomposition mechanism of HCHO was researched using TiO₂ aerogels with varying pore sizes as catalysts. The results indicated that the pore size of TiO₂ aerogels was one of the important factors for HCHO decomposition. We validated that the efficiency of HCHO decomposition was related to the oxygen pressure in the pores of the TiO₂ aerogel, and the oxygen pressure was inversely proportional to the pore size, then the pore size of the TiO₂ aerogel and the decomposition efficiency of HCHO were linked through the oxygen pressure. Finally, the optimal pore size of the TiO₂ aerogel for the photocatalytic HCHO decomposition was 2 nm–10 nm. The present study aims to establish the relationship and influence of the pore size of TiO₂ aerogels on the performance of photocatalytic decomposition and promoting further advancements in porous nanomaterials for catalysis. Full article

(This article belongs to the Special Issue Cutting-Edge Catalytic Strategies for Organic Pollutant Mitigation)

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24 pages, 5999 KiB

Open AccessFeature PaperArticle

Unravelling Vacuum Gas Oil Catalytic Cracking: The Influence of the Catalyst-to-Oil Ratio on FCC Catalyst Performance

by Jansen Gabriel Acosta-López, José Luis Muñoz and Hugo de Lasa

Catalysts 2025, 15(2), 170; https://doi.org/10.3390/catal15020170 - 12 Feb 2025

Abstract

This study evaluates the impact of the catalyst-to-oil (C/O) ratio in the 1 to 7 range on the catalytic cracking of vacuum gas oil (VGO). Experiments are conducted using fluid catalytic cracking (FCC)-type catalysts, in a mini-fluidized bench-scale Riser Simulator reactor invented at [...] Read more.

This study evaluates the impact of the catalyst-to-oil (C/O) ratio in the 1 to 7 range on the catalytic cracking of vacuum gas oil (VGO). Experiments are conducted using fluid catalytic cracking (FCC)-type catalysts, in a mini-fluidized bench-scale Riser Simulator reactor invented at the Chemical Reactor Engineering Centre (CREC), University of Western Ontario. The CREC Riser Simulator replicates FCC industrial operating conditions such as temperature, species partial pressure, and reaction times. The results indicate that increasing the C/O ratio above 5 slightly impacts VGO conversion, increases light gases yield, decreases light cycle oil (LCO) yield, and stabilizes gasoline yield. These findings align with temperature-programmed desorption (TPD) data, showing how the retention of a larger number of acid sites at a C/O of 7 boosts light gas production and reduces LCO selectivity. These elevated C/O ratios also lead to higher coke formation. The results reported together with future studies conducted by our research team on the impact of higher catalyst flows, larger potential catalyst attrition, higher catalyst loading in the cyclones, and excess heat generated in the catalyst regenerator unit, are of critical value for establishing the impact of C/O ratios in the overall FCC refinery operation. Full article

(This article belongs to the Section Catalytic Reaction Engineering)

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20 pages, 19226 KiB

Open AccessFeature PaperArticle

Solid-Phase Activation During the Degradation of Tetracycline by Modified Activated Carbon–Persulfate Composite

by Shihu Ding, Peng Tan, Nuo Meng, Xiguo Zhang, Lin Ma, Minghua Zhou and Wei Wang

Catalysts 2025, 15(2), 169; https://doi.org/10.3390/catal15020169 - 12 Feb 2025

Abstract

In this study, the novel composite materials of activated carbon (AC) and persulfate (PS) doped by nitrogen (N) and sulfur (S) were successfully synthesized through one-step mechanical ball milling. Different from the previous liquid-phase activation process of PS, the direct in situ solid-phase [...] Read more.

In this study, the novel composite materials of activated carbon (AC) and persulfate (PS) doped by nitrogen (N) and sulfur (S) were successfully synthesized through one-step mechanical ball milling. Different from the previous liquid-phase activation process of PS, the direct in situ solid-phase activation of PS was achieved through the newly generated chemical bonds between AC and PS. The increased crystal surface exposure and highly electronegative atoms provided more reactive sites for the modified composites, enabling them to extract electrons from the pollutant. Compared to S doping, the N-doped composite exhibited a higher oxidative degradation ability, with a removal rate of 93.6% for tetracycline (TC, 40 mg/L) within 40 min. The interactions between AC and PS that occur in the interior of the composite avoid the limitations of mass transfer between the solid–liquid interface, thus expanding the pH application range of the catalytic reaction and minimizing the interference of other components in the solution. The synergistic effect between active oxygen species and electron transfer is the main mechanism for promoting pollutant degradation. This research puts forward a new insight into the activation approach of PS and proposes a feasible method for the advanced treatment of TC wastewater. Full article

(This article belongs to the Section Environmental Catalysis)

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22 pages, 3391 KiB

Open AccessArticle

Enantioselectivity Enhancement of a Geobacillus thermoleovorans CCR11 Lipase by Rational Design

by Aaron-Salvador Bustos-Baena, Rodolfo Quintana-Castro, María Guadalupe Sánchez-Otero, Graciela Espinosa-Luna, María Remedios Mendoza-López, Carolina Peña-Montes and Rosa María Oliart-Ros

Catalysts 2025, 15(2), 168; https://doi.org/10.3390/catal15020168 - 12 Feb 2025

Abstract

Lipases are enzymes that catalyze the hydrolysis of carboxylic esters at a lipid–water interface and are able to catalyze reactions such as alcoholysis, esterification, transesterification, and enantioselective synthesis in organic media. They are important biocatalysts for biotechnological and industrial applications—such as in the [...] Read more.

Lipases are enzymes that catalyze the hydrolysis of carboxylic esters at a lipid–water interface and are able to catalyze reactions such as alcoholysis, esterification, transesterification, and enantioselective synthesis in organic media. They are important biocatalysts for biotechnological and industrial applications—such as in the food and flavor industry—and in the production of biopharmaceuticals, biofuels, biopolymers, and detergents. A desirable property of lipases is stereoselectivity for the production of chemicals with high optical purity. In this work, we report the improvement of the enantioselective capabilities of the Geobacillus thermoleovorans CCR11 lipase. By means of a rational design and bioinformatic approaches, six amino acids of the catalytic cavity of the lipase LipTioCCR11 were substituted resulting in an increase in the optimum temperature of the enzyme and in the resistance to the presence of organic solvents in hydrolytic reactions, and in the promotion of the enantioselective recognition of R isomers of carboxylic acids with importance for the pharmaceutical and food industries. Full article

(This article belongs to the Special Issue New Trends in Industrial Biocatalysis, 2nd Edition)

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16 pages, 3453 KiB

Open AccessFeature PaperArticle

Enhancing Photocatalytic Hydrogen Evolution with Oxygen Vacancy-Modified P/Ag/Ag₂O/Ag₃PO₄/TiO₂ by Using Optimized NaBH₄ Reduction Strategy

by Xiang Sun, Yunxin Zhu, Guangqi An, Guoping Chen and Yingnan Yang

Catalysts 2025, 15(2), 167; https://doi.org/10.3390/catal15020167 - 11 Feb 2025

Abstract

The introduction of oxygen vacancies (OVs) is a promising strategy to enhance the hydrogen (H₂) evolution efficiency of photocatalysts. Sodium borohydride (NaBH₄) is widely used as a reducing agent to introduce OVs, particularly in composite materials. However, its impact [...] Read more.

The introduction of oxygen vacancies (OVs) is a promising strategy to enhance the hydrogen (H₂) evolution efficiency of photocatalysts. Sodium borohydride (NaBH₄) is widely used as a reducing agent to introduce OVs, particularly in composite materials. However, its impact on H₂ evolution remains underexplored. In this study, by employing various mass ratios of NaBH₄ to P/Ag/Ag₂O/Ag₃PO₄/TiO₂ (PAgT), OVs modified PAgT (R-PAgT) composites, which were synthesized and systematically characterized by XRD, FT-IR, and XPS. R-PAgT-10 with an optimal mass ratio exhibited a superior H₂ evolution efficiency and stability, maintaining its performance over 20 cycles under visible light irradiation, while the higher mass ratio of NaBH₄/PAgT led to the disruption of the crystal structure with excessive OVs amounts, resulting in poor stability. This study highlighted the importance of utilizing the optimal mass ratio of NaBH₄ to prepare OVs-PAgT for successful and stable H₂ evolution under visible light irradiation, which holds promise for developing efficient and durable photocatalysts for renewable energy applications. Full article

(This article belongs to the Special Issue Photocatalytic/Photoelectrocatalysis Water Splitting)

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20 pages, 6311 KiB

Open AccessArticle

The Effect of Vacuum Annealing on the Structural, Electric, and Optical Properties, and Photocatalytic Activities of Sputtered TiO₂ and Nb-Doped TiO₂ Films

by Mengna Li, Yingying Fang and Baoshun Liu

Catalysts 2025, 15(2), 166; https://doi.org/10.3390/catal15020166 - 11 Feb 2025

Abstract

TiO₂ is still a prototype material in photocatalytic studies. The defects, including the intrinsic and foreign defects, are reported to be important in determining the TiO₂ photocatalytic properties. In the current research, amorphous TiO₂- and Nb-doped TiO₂ (NTO) [...] Read more.

TiO₂ is still a prototype material in photocatalytic studies. The defects, including the intrinsic and foreign defects, are reported to be important in determining the TiO₂ photocatalytic properties. In the current research, amorphous TiO₂- and Nb-doped TiO₂ (NTO) films were firstly prepared through magnetron sputtering, which were then heated under vacuum. The as-deposited TiO₂ and NTO films were amorphous, and transferred to anatase after heating. The vacuum heating at a higher temperature caused an obvious reduction in TiO₂ films, and the NTO film was more prone to be reduced as Nb dopants decreased the thermal stability of the TiO₂ lattice. The structure change induced by vacuum annealing had a great effect on electric and optical properties. The conductivity of the NTO films was 10,000 times and 100 times higher than that of the undoped TiO₂ films after post-vacuum heating at 450 °C and 650 °C, respectively. In addition to an increase in the band tail absorption, the NTO films presented strong free-electron absorption after vacuum heating; this means that the NTO films presented a clear Bornstein moss shift after vacuum heating because of the high conduction electron density. The change in the photoinduced absorption spectra revealed a possible result that photo-induced electrons can be also trapped at Nb sites, indicating that the Nb-related defect forms deep gap states; this greatly limits the photo-induced electron interfacial transfer. The results showed that the photocatalytic degradation of methylene blue decreased after vacuum heating. Full article

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

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23 pages, 7261 KiB

Open AccessArticle

Excellent Photocatalytic Performance Against Amoxicillin Antibiotic and Pt-Free Hydrogen Production Using Fe-Doped ZnS Nanostructures: Reaction Kinetics and Mechanistic Insights

by Ali Raza, Syeda Takmeel Zahra, Hadia Noor, Shahzad Naseem, Saira Riaz, Mohammad Ehtisham Khan, Wahid Ali, Mohammad S. Alomar, Anwar Ulla Khan, Syed Kashif Ali, Nazim Hasan and Waleed Zakri

Catalysts 2025, 15(2), 165; https://doi.org/10.3390/catal15020165 - 11 Feb 2025

Abstract

This research presents the synthesis of Fe-doped ZnS nanocomposites via a chemical route, exploring their photocatalytic activity against amoxicillin (AMX) and evaluating their hydrogen production potential. The synthesized nanocomposites were characterized by several state-of-the-art analytical techniques, such as XRD, SEM, PL, UV adsorption, [...] Read more.

This research presents the synthesis of Fe-doped ZnS nanocomposites via a chemical route, exploring their photocatalytic activity against amoxicillin (AMX) and evaluating their hydrogen production potential. The synthesized nanocomposites were characterized by several state-of-the-art analytical techniques, such as XRD, SEM, PL, UV adsorption, Raman, TEM, and AFM. The photocatalytic performance revealed significant degradation of AMX under optimal conditions. Specifically, Fe-doped ZnS nanocomposites achieved a degradation efficiency of 94% within 120 min at a photocatalyst dosage of 110 mg. The pristine ZnS nanoparticles exhibited a hydrogen production rate of 23.6 µmol·g⁻¹·h⁻¹, whereas Fe doping substantially enhanced this rate to 526.6 µmol·g⁻¹·h⁻¹ under optimized conditions. The optimal temperature for hydrogen production was 200 °C, with maximum efficiency at pH 7. Furthermore, the recyclability tests demonstrated that the photocatalyst maintained a considerable hydrogen production rate over multiple cycles, underscoring its potential for commercial nanotechnology and environmental science applications. Full article

(This article belongs to the Special Issue Photocatalytic/Photoelectrocatalysis Water Splitting)

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