Catalysts

19 pages, 1506 KiB

Open AccessArticle

Photodegradation of Pyridine in a Fluidized Bed Photocatalytic Reactor Using Pt-ZnO Supported on Al₂O₃ as a Catalyst

by Ruby Gines, Carlos Montalvo, Guadalupe Luna, Daniel Montalvo, Rosa M. Cerón, Julia G. Cerón, Sinuhe Ginés, Aracely García and Claudia A. Aguilar

Catalysts 2025, 15(8), 772; https://doi.org/10.3390/catal15080772 (registering DOI) - 13 Aug 2025

Abstract

Pyridine is a recalcitrant organic compound present in industrial wastewater that causes severe effects on the environment and the health of living beings, as it is considered a toxic, mutagenic, teratogenic, and carcinogenic agent. Therefore, this research explored the efficacy of a zinc [...] Read more.

Pyridine is a recalcitrant organic compound present in industrial wastewater that causes severe effects on the environment and the health of living beings, as it is considered a toxic, mutagenic, teratogenic, and carcinogenic agent. Therefore, this research explored the efficacy of a zinc oxide catalyst, doped with platinum nanoparticles and supported alumina through the precipitation method, for the photocatalytic degradation of pyridine using a fluidized bed reactor. A Box–Behnken experimental design was used to analyze the effect of the pH (4–10), the pyridine concentration (20–300 ppm), and the amount of catalyst (20–100 g). The X-ray diffraction (XRD) characterization results confirmed the hexagonal structure of the zinc oxide and the successful incorporation of platinum. Scanning electron microscopy (SEM) revealed a nano-bar morphology upon catalyst doping, favoring the photocatalytic activity. Pyridine removal of 57.7% was achieved under the following conditions: a pH of 4, 160 ppm of pyridine, and 100 g of catalyst. The process followed a pseudo-first-order model, obtaining the reaction constant k₁ = 1.943 × 10⁻³ min⁻¹ and the adsorption constant k₂ = 1.527 × 10⁻³ L/mg. The results showed high efficiency and stability of the catalyst in the fluidized bed reactor for pyridine degradation, especially under acidic conditions, representing a promising technological alternative for treating industrial wastewater contaminated with N-heterocycles such as pyridine. Full article

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

14 pages, 3138 KiB

Open AccessFeature PaperArticle

Construction of BiOBr/BNQDs Heterostructure Photocatalyst and Performance Studies of Photocatalytic Degradation of RhB

by Yufeng Qin, Xinyu Peng, Tong Wu, Yi Zhong, Hong Xu, Zhiping Mao and Linping Zhang

Catalysts 2025, 15(8), 771; https://doi.org/10.3390/catal15080771 - 13 Aug 2025

Abstract

As a common semiconductor material, BiOBr has a unique layered structure and a suitable bandgap. However, the slow electron–hole separation efficiency leads to poor photocatalytic performance. To solve this problem, BiOBr/BNQDs heterojunctions were constructed. BiOBr/BNQDs composite photocatalysts were prepared by the solvothermal method, [...] Read more.

As a common semiconductor material, BiOBr has a unique layered structure and a suitable bandgap. However, the slow electron–hole separation efficiency leads to poor photocatalytic performance. To solve this problem, BiOBr/BNQDs heterojunctions were constructed. BiOBr/BNQDs composite photocatalysts were prepared by the solvothermal method, and the cocatalyst BNQDs were loaded onto BiOBr via electrostatic adsorption to enhance the photocatalytic degradation activity towards Rhodamine B (RhB). The photocatalysts were characterized by FT-IR, XRD, XPS, SEM-EDS, UV-Vis, PL, EIS, etc. Compared with pure BiOBr, the construction of heterojunctions BiOBr/BNQDs realized the rapid elimination of weak carriers and the effective separation and enrichment of high-energy carriers, which improved the efficiency of photocatalytic degradation of RhB. Among them, BiOBr/BNQDs-8.3% demonstrated the highest photocatalytic activity. The degradation rate of RhB under visible light irradiation for 60 min was up to 98.56%, and the reaction rate constant was 0.0696 min⁻¹, which was 2.80 times that of pure BiOBr. Moreover, after five photocatalytic cycles, the degradation rate was still 87.58%, demonstrating good cycling stability. Full article

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

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13 pages, 5037 KiB

Open AccessFeature PaperArticle

First-Principles Study of Sn-Doped RuO₂ as Efficient Electrocatalysts for Enhanced Oxygen Evolution

by Caiyan Zheng, Qian Gao and Zhenpeng Hu

Catalysts 2025, 15(8), 770; https://doi.org/10.3390/catal15080770 - 13 Aug 2025

Abstract

Improving the catalytic performance of the oxygen evolution reaction (OER) for water splitting in acidic media is crucial for the production of clean and renewable hydrogen energy. Herein, we study the OER electrocatalytic properties of various active sites on four exposed (110) and [...] Read more.

Improving the catalytic performance of the oxygen evolution reaction (OER) for water splitting in acidic media is crucial for the production of clean and renewable hydrogen energy. Herein, we study the OER electrocatalytic properties of various active sites on four exposed (110) and (

\bar{1}

10) surfaces of Sn-doped RuO₂ (Sn/RuO₂) with antiferromagnetic arrangements in acidic environments. The Sn/RuO₂ bulk structure with the Cm space group exhibits favorable thermodynamic stability. The coordinatively unsaturated metal (M_cus) sites distributed on the right branch of the volcano plot are generally more active than the bridge-bonded lattice oxygen (O_br) sites located on the left. Different from the conventional knowledge that the most active site is located in the nearest neighbor of the doped atom, it has a lower OER overpotential when the active site is 3.6 Å away from the doped Sn atom. Among the sites studied, the 46-Ru_cus site exhibits the optimal OER catalytic performance. The inherent factors affecting the OER activity of each site on the Sn/RuO₂ surface are further analyzed, including the center of the d/p band at the active sites, the average electrostatic potential of the ions, and the number of transferred electrons. This work provides a reminder for the selection of active sites used to evaluate catalytic performance, which will benefit the development of efficient OER electrocatalysts. Full article

(This article belongs to the Topic Water Splitting and CO₂ Reduction via Electrocatalysis and Photocatalysis)

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13 pages, 6309 KiB

Open AccessArticle

Reusable Three-Dimensional TiO₂@MoS₂ Core–Shell Photoreduction Material: Designed for High-Performance Seawater Uranium Extraction

by Chen Xie, Tianyi Zhao, Feng Zhou and Bohao Zhao

Catalysts 2025, 15(8), 769; https://doi.org/10.3390/catal15080769 - 13 Aug 2025

Abstract

Photocatalysis offers a cost-effective and eco-friendly approach for environmental remediation, yet traditional powdered photocatalysts suffer from poor recyclability and separation challenges. To address these limitations, we developed a recyclable carbon fiber-supported composite photocatalyst (CC/TiO₂ NRs@MoS₂ NPs) featuring a three-dimensional hierarchical core–shell [...] Read more.

Photocatalysis offers a cost-effective and eco-friendly approach for environmental remediation, yet traditional powdered photocatalysts suffer from poor recyclability and separation challenges. To address these limitations, we developed a recyclable carbon fiber-supported composite photocatalyst (CC/TiO₂ NRs@MoS₂ NPs) featuring a three-dimensional hierarchical core–shell architecture. This structure comprises a TiO₂ seed layer, vertically aligned TiO₂ nanorod arrays as the core, and a MoS₂ nanoparticle shell, fabricated via sequential deposition. Under simulated solar irradiation, the TiO₂@MoS₂ heterojunction exhibited significantly enhanced uranium adsorption capacity, achieving a remarkable 97.3% photocatalytic removal efficiency within 2 h. At an initial uranium concentration of 200 ppm, the material demonstrated an exceptional extraction capacity of 976.7 mg g⁻¹, outperforming most reported photocatalysts. These findings highlight the potential of this 3D core–shell design for efficient uranium recovery and environmental purification applications. Full article

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

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24 pages, 5693 KiB

Open AccessFeature PaperArticle

Relationship Between Number and Strength of Acid–Base Catalytic Sites and Their Performances in Isopropanol Dehydration Reaction

by Georgeta Postole, Sandra Segondy, Tristan Cabanis, Tien-Hoang Nguyen, Aline Auroux and Jean-Luc Dubois

Catalysts 2025, 15(8), 768; https://doi.org/10.3390/catal15080768 - 12 Aug 2025

Abstract

Commercial alumina and silica–alumina catalysts were investigated for propylene (PEN) production via an isopropanol (IPA) dehydration reaction between 200 and 300 °C at an atmospheric pressure and IPA partial pressure of 5136 Pa. The reaction conditions were chosen to fit with the further [...] Read more.

Commercial alumina and silica–alumina catalysts were investigated for propylene (PEN) production via an isopropanol (IPA) dehydration reaction between 200 and 300 °C at an atmospheric pressure and IPA partial pressure of 5136 Pa. The reaction conditions were chosen to fit with the further conversion of PEN into value-added compounds with minimal capital cost, and the conceptual process design was discussed. The textural properties, structure and chemical composition of as-received and hydrothermally treated catalysts were characterised by the adsorption–desorption of N₂, X-ray fluorescence, X-ray diffraction and Nuclear Magnetic Resonance spectroscopy. The adsorption microcalorimetry of NH₃ and SO₂ was used to determine the amount, strength and strength distribution of acid–base sites, while the nature of the acid sites was investigated by Fourier Transform Infraed spectroscopy. Surface area, pore-size distribution and pore volume were not determining factors for the catalytic performances of studied solids in the conditions used here. The best-performing catalyst combined stable textural properties and a high number of high-strength acid sites (Q_diff > 150 kJ/mol NH₃) under hydrothermal conditions. The importance of determining the number and strength of acid sites of water-aged catalysts, when considering reactions where water is present as reactive or product, is underlined. Full article

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18 pages, 6481 KiB

Open AccessArticle

Integrating Carbon-Coated Cu/Cu₂O Nanoparticles with Biochars Enabled Efficient Capture and Electrocatalytic Reduction of CO₂

by Yutong Hong, Xiaokai Zhou and Fangang Zeng

Catalysts 2025, 15(8), 767; https://doi.org/10.3390/catal15080767 - 11 Aug 2025

Viewed by 30

Abstract

Because the interfacial Cu⁰/Cu⁺ in Cu-based electrocatalyst promotes CO₂ electroreduction activity, it would be highly desirable to physically separate Cu-based nanoparticles through coating shells and load them onto porous carriers. Herein, multilayered graphene-coated Cu (Cu@G) nanoparticles with tailorable core [...] Read more.

Because the interfacial Cu⁰/Cu⁺ in Cu-based electrocatalyst promotes CO₂ electroreduction activity, it would be highly desirable to physically separate Cu-based nanoparticles through coating shells and load them onto porous carriers. Herein, multilayered graphene-coated Cu (Cu@G) nanoparticles with tailorable core diameters (28.2–24.2 nm) and shell thicknesses (7.8–3.0 layers) were fabricated via lased ablation in liquid. A thin Cu₂O layer was confirmed between the interface of the Cu core and the graphene shell, providing an interfacial Cu⁰/Cu⁺. Cu@G cross-linked biochars (Cu@G/Bs) with developed porosity (31.8–155.9 m²/g) were synthesized. Morphology, crystalline structure, porosity, and elemental chemical states of Cu@G and Cu@G/Bs were characterized. Cu@G/Bs captured CO₂ with a maximum sorption capacity of 107.03 mg/g at 0 °C. Furthermore, 95.3–97.1% capture capacity remained after 10 cycles. Cu@G/Bs exhibited the most superior performance with 40.7% of FE_C2H4 and 21.7 mA/cm² of current density at −1.08 V vs. RHE, which was 1.7 and 2.7 times higher than Cu@G. Synergistic integration of developed porosity for efficient CO₂ capture and the fast charge transfer rate of interfacial Cu₂O/Cu enabled this improvement. Favorable long-term stability of the phase/structure and CO₂ electroreduction activity were present. This work provides new insight for integrating Cu@G and a biochar platform to efficiently capture and electro-reduce CO₂. Full article

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12 pages, 3743 KiB

Open AccessArticle

Preparation of Bilirubin Through the Biotransformation of Biliverdin Using Whole Cells of Recombinant Yeast

by Hong Chen, Shihang Zhuang, Yanchao Han, Wei Ke and Jianfeng Mei

Catalysts 2025, 15(8), 766; https://doi.org/10.3390/catal15080766 - 11 Aug 2025

Viewed by 31

Abstract

Bilirubin is a key component in the preparation of two traditional Chinese medicines: Calculus bovis sativus and Calculus bovis artifactus. Currently, industrial-scale production of bilirubin is limited to extraction from pig bile in a very low yield and its market price is [...] Read more.

Bilirubin is a key component in the preparation of two traditional Chinese medicines: Calculus bovis sativus and Calculus bovis artifactus. Currently, industrial-scale production of bilirubin is limited to extraction from pig bile in a very low yield and its market price is very high, so it is important to develop an alternative method for producing bilirubin. This study developed a potential process for bilirubin production through biotransformation of biliverdin. The codon-optimized gene for biliverdin reductase (BVR) from Synechocystis PCC6803 was recombinantly expressed in Komagataella phaffii GS115, resulting in the genetically modified strain GS115-bvdR, which successfully expressed BVR with intracellular activity. Whole cells of GS115-bvdR were capable of transforming biliverdin to bilirubin in vitro. The overexpression conditions were optimized to enhance BVR production by GS115-bvdR, and the optimal conditions for the biotransformation of biliverdin into bilirubin using resting GS115-bvdR cells were established (pH 5.0 buffer, at 30 °C for 24 h, with 200 mg/L biliverdin). Under these conditions, a bilirubin concentration of 153 mg/L was achieved, with a conversion of 76.2% from biliverdin. These findings provide valuable insights for future studies on the biosynthesis of bilirubin through metabolic engineering. Full article

(This article belongs to the Special Issue Enzyme and Biocatalysis Application)

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10 pages, 1835 KiB

Open AccessArticle

Evaluation of a Pilot-Scale Water Treatment System with Passive Aerated, Membraneless Microbial Fuel Cell

by Zabdiel A. Juarez, Víctor Ramírez, Carlos Hernández-Benítez, Luis A. Godínez, Irma Robles Gutierrez and Francisco J. Rodríguez-Valadez

Catalysts 2025, 15(8), 765; https://doi.org/10.3390/catal15080765 - 9 Aug 2025

Viewed by 188

Abstract

Wastewater treatment has become a priority in the global attempt to address environmental pollution. Conventional wastewater treatment processes are often limited by their high energy consumption, so it is necessary to develop new technologies. This work shows the results obtained using a passive [...] Read more.

Wastewater treatment has become a priority in the global attempt to address environmental pollution. Conventional wastewater treatment processes are often limited by their high energy consumption, so it is necessary to develop new technologies. This work shows the results obtained using a passive aerated membraneless microbial fuel cell (PAML-MFC) system consisting of 10 individual units, designed to treat 1000 L/day of real wastewater, using granular activated carbon anodes and cathodes. The pilot-scale water treatment system under study combines design and materials to result in low-cost operation. After 300 days of treating real wastewater originally characterized by a chemical oxygen demand (COD) value of 500 mg/L on average, it was found that the PAML-MFC under study removed 60 to 80% of the COD contained in real wastewater. Under these conditions, the individual MFCs reached an average power density below 1 mW/m³. Full article

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13 pages, 3882 KiB

Open AccessFeature PaperArticle

Energy-Saving-Targeted Solar Photothermal Dehydration and Confined Catalytic Pyrolysis of Oily Sludge Using Wood Sponge Loaded with Carbon Dots

by Chujun Luan, Huiyi Mao, Fawei Lin and Hongyun Yao

Catalysts 2025, 15(8), 764; https://doi.org/10.3390/catal15080764 - 9 Aug 2025

Viewed by 154

Abstract

Pyrolysis of oily sludge (OS) faces two significant challenges, dehydration in emulsion and coke formation, which cause extra energy consumption. Targeting energy saving, this paper first reported on solar photothermal dehydration and confined catalytic pyrolysis of OS using a single material. A wood [...] Read more.

Pyrolysis of oily sludge (OS) faces two significant challenges, dehydration in emulsion and coke formation, which cause extra energy consumption. Targeting energy saving, this paper first reported on solar photothermal dehydration and confined catalytic pyrolysis of OS using a single material. A wood sponge loaded with carbon dots (CM-CDs) can generate heat by absorbing solar energy and promote rapid phase separation and water transport via capillary action of oil–water emulsion in OS under sunlight. Almost all free water in OS with varied content can be removed after 3 h. Hydrocarbons entered the internal space of CM-CDs instead of contacting with soil minerals, contributed to the subsequent confined catalytic pyrolysis, led to a reduction in Ea (35.61 kJ/mol), inhibited coking and caking, and yielded higher oil recovery efficiency. In addition, CDs can form hotspots to enhance pyrolytic behaviors in local regions. When the ratio of OS to CM-CDs reached 10:0.6, the recovery rate of the oil fraction through combined pyrolysis was as high as 89%, which was 17% higher than that of OS pyrolysis alone. This discovery provides a new way to solve the bottleneck problems of OS pyrolysis in the industry. Full article

(This article belongs to the Special Issue Catalysis Accelerating Energy and Environmental Sustainability)

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12 pages, 2983 KiB

Open AccessFeature PaperArticle

Rare-Earth-Element-Doped NiCo Layered Double Hydroxides for High-Efficiency Oxygen Evolution

by Zhihan Li, Wenjing Yi, Qingqing Pang, Meng Zhang and Zhongyi Liu

Catalysts 2025, 15(8), 763; https://doi.org/10.3390/catal15080763 - 9 Aug 2025

Viewed by 208

Abstract

The development of low-cost and high-efficiency oxygen evolution reaction (OER) catalysts is essential to enhance the practicality of electrochemical water splitting for green hydrogen production. Layered double hydroxides (LDHs), especially those based on nickel and cobalt, have attracted attention due to their tunable [...] Read more.

The development of low-cost and high-efficiency oxygen evolution reaction (OER) catalysts is essential to enhance the practicality of electrochemical water splitting for green hydrogen production. Layered double hydroxides (LDHs), especially those based on nickel and cobalt, have attracted attention due to their tunable composition, abundant redox-active sites, and earth-abundant constituents. However, their application is hindered by their limited conductivity and sluggish reaction kinetics. In this study, rare-earth-element-doped NiCo LDHs were synthesized directly on nickel foam through a one-step hydrothermal approach to improve the OER activity by modulating the electronic structure and optimizing the surface morphology. Among the representative catalysts, the incorporation of Sm significantly influenced the microstructure and electronic configuration of the catalyst, as confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical tests showed that the optimized Sm-NiCo LDH achieved a low overpotential of 172 mV at 10 mA cm⁻² and a small Tafel slope of 84 mV dec⁻¹ in 1 M KOH, indicating an expanded electrochemically active surface and improved charge transport. Long-term stability tests further showed its durability. These findings suggest that Sm doping enhances the OER performance by increasing active site exposure and promoting efficient charge transfer, offering a promising strategy for designing rare-earth-modified, non-precious-metal-based OER catalysts. Full article

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17 pages, 7637 KiB

Open AccessArticle

Metal Oxide-Doped Pd-Based Catalysts for Enhanced Formaldehyde Oxidation

by Bohao Chang, Xingyu Li, Zeren Rong, Xingshu Wang and Zhihui Liu

Catalysts 2025, 15(8), 762; https://doi.org/10.3390/catal15080762 - 9 Aug 2025

Viewed by 198

Abstract

In this study, a novel strategy to enhance the performance of palladium (Pd)-based catalysts by doping with metal oxides (Mn₃O₄, MoO₃, and SnO) has been developed in order to overcome the limitations of its low activity and [...] Read more.

In this study, a novel strategy to enhance the performance of palladium (Pd)-based catalysts by doping with metal oxides (Mn₃O₄, MoO₃, and SnO) has been developed in order to overcome the limitations of its low activity and high cost in the catalytic oxidation of formaldehyde (HCHO). The novelty of this strategy lies in the fact that by precisely controlling the types and doping ratios of the metal oxides, a significant enhancement of the electrochemical performance and catalytic activity of the Pd-based catalysts was achieved, while the dependence on precious metals was reduced and the cost-effectiveness of the catalysts was improved. The effects of different metal oxide doping on the catalytic performance were systematically investigated by electrochemical characterization and catalytic activity tests. Among the prepared catalysts, Pd-Mn₃O₄ showed the most excellent performance, with an electrochemically active surface area of 20.6 m²/g and a formaldehyde oxidation reaction (FOR) current density of 3.5 mA/cm², which were 31.6% and 169.2% higher than pure Pd, respectively. In a 1000 s timed current method stability test, the limiting current density of Pd-Mn₃O₄ reached 0.48 mA/cm², which is 4.4 times higher than that of pure Pd. The excellent catalytic performance is attributed to the abundant surface hydroxyl (-OH) groups provided by Mn₃O₄, which contribute to the oxidation of formaldehyde intermediates, as well as the electronic synergistic effect between Pd and Mn₃O₄, which is manifested as a 0.4 eV downshift of the Pd 3d binding energy. In addition, the sensor evaluation showed that the Pd-Mn₃O₄-based formaldehyde sensor exhibited a high sensitivity (1.5 μA/ppm), excellent linearity (R² = 0.995), minimal long-term degradation (<7% in 30 days), and ~20-fold selectivity for formaldehyde over interfering gases (e.g., ethanol). This study provides a theoretical basis and practical material reference for the development of efficient and low-cost catalysts for formaldehyde oxidation. Full article

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45 pages, 2230 KiB

Open AccessFeature PaperReview

Recent Progress in Catalytically Driven Advanced Oxidation Processes for Wastewater Treatment

by Tian-Hua Zheng, Zhen-Zhong Zhang, Yue Liu and Liang-Hua Zou

Catalysts 2025, 15(8), 761; https://doi.org/10.3390/catal15080761 - 8 Aug 2025

Viewed by 218

Abstract

With the increasing severity of global water pollution, traditional wastewater treatment methods have gradually revealed limitations in dealing with complex and refractory pollutants. Advanced oxidation processes (AOPs) have emerged as a promising alternative due to their ability to generate highly reactive radicals (such [...] Read more.

With the increasing severity of global water pollution, traditional wastewater treatment methods have gradually revealed limitations in dealing with complex and refractory pollutants. Advanced oxidation processes (AOPs) have emerged as a promising alternative due to their ability to generate highly reactive radicals (such as hydroxyl and sulfate radicals) that can effectively degrade a wide range of pollutants. This review provides a detailed overview of various AOP technologies, including Fenton processes, ozone-based AOPs, persulfate-based AOPs, photocatalytic AOPs, electrochemical AOPs, and sonochemical AOPs, focusing on their fundamental principles, reaction mechanisms, catalyst design, and application performance in treating different types of wastewater. The research results show that the improved Fenton process can achieve a chemical oxygen demand (COD) removal rate of up to 85% when treating pharmaceutical wastewater. Photocatalytic AOP technology demonstrates higher degradation efficiency when treating industrial wastewater containing refractory pollutants. In addition to effectively degrading refractory pollutants and reducing dependence on traditional biological treatment methods, these advanced oxidation processes can also significantly reduce secondary pollution generated during the treatment process. Moreover, by optimizing AOP technologies, the deep mineralization of harmful substances in wastewater can be achieved, reducing the potential pollution risks to groundwater and soil while also lowering energy consumption during the treatment process. Additionally, this review discusses the challenges faced by AOPs in practical applications, such as high energy consumption, insufficient catalyst stability, and secondary pollution. This review summarizes the research progress and application trends of catalytically driven AOPs in the field of wastewater treatment over the past five years. It aims to provide a comprehensive reference for researchers and engineering professionals on the application of AOPs in wastewater treatment, promoting the further development and practical implementation of these technologies. Full article

(This article belongs to the Collection Catalysis in Advanced Oxidation Processes for Pollution Control)

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15 pages, 2015 KiB

Open AccessArticle

Influence of Calcination and Reduction Conditions of Ni-Al-LDH Catalysts for CO₂ Methanation

by Nailma Martins and Oscar W. Perez-Lopez

Catalysts 2025, 15(8), 760; https://doi.org/10.3390/catal15080760 - 8 Aug 2025

Viewed by 248

Abstract

CO₂ methanation offers a sustainable route to reduce greenhouse gas emissions by converting carbon dioxide into methane, a valuable renewable fuel. This exothermic reaction not only mitigates its environmental impact but also provides energy-efficient benefits, as the heat generated can be reused [...] Read more.

CO₂ methanation offers a sustainable route to reduce greenhouse gas emissions by converting carbon dioxide into methane, a valuable renewable fuel. This exothermic reaction not only mitigates its environmental impact but also provides energy-efficient benefits, as the heat generated can be reused in industrial applications. In this study, CO₂ methanation was carried out in a continuous flow reactor with a CO₂:H₂ molar ratio of 1:4 and a gas hourly space velocity (GHSV) of 12,000 h⁻¹, using a Ni-Al-LDH catalyst with a molar ratio of 2.3. The research focused on how calcination and reduction conditions affect catalyst structure and activity. Characterization techniques such as BET, XRD, TPR, H₂-TPD, and CO₂-TPD revealed that these conditions significantly influence surface area, crystallinity, phase composition, and metal dispersion. A higher reduction temperature decreased the surface area and increased both the crystallite size and basicity. The findings highlight that thermal treatment play a crucial role in optimizing the catalytic properties of NiAl catalyst. The sample calcined at 600 °C showed greater activity at lower reaction temperatures, while the catalyst calcined at 400 °C performed better above 300 °C. Additionally, the evaluation of the effect of the reduction atmosphere during catalyst activation showed that H₂ is a more effective reducing gas at lower reaction temperatures, whereas biogas showed a better performance at higher temperatures. Importantly, XRD results showed the catalysts maintained their structural integrity post-reaction, with no significant carbon deposition in the H₂ atmosphere, confirming their potential for long-term application in CO₂ methanation. Full article

(This article belongs to the Special Issue Catalysis and Technology for CO₂ Capture, Conversion and Utilization)

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16 pages, 6767 KiB

Open AccessArticle

Macroporous Resin-Based La-N Co-Doped TiO₂ Composites for Efficient Removal of Environmental Pollutants in Water via Integrating Adsorption and Photocatalysis

by Wenbin Qu, Bountheva Louangsouphom, Xiaoling Ye, Huimei Liu and Xin Wang

Catalysts 2025, 15(8), 759; https://doi.org/10.3390/catal15080759 - 8 Aug 2025

Viewed by 228

Abstract

Integrating photocatalysis with adsorption represents an efficient approach to improving the removal performance of organic contaminants from aqueous environments. To address the issues of severe charge recombination and poor adsorption activity in TiO₂ photocatalysts during the photocatalytic degradation of organic pollutants. In [...] Read more.

Integrating photocatalysis with adsorption represents an efficient approach to improving the removal performance of organic contaminants from aqueous environments. To address the issues of severe charge recombination and poor adsorption activity in TiO₂ photocatalysts during the photocatalytic degradation of organic pollutants. In this study, we used macroporous resin as a carrier and prepared La/N-doped TiO₂/macroporous resin composite materials (La/N/TiO₂-MAR) via a hydrothermal-assisted sol–gel method. The results show that the composite material has a spherical morphology. N can be doped into the TiO₂ crystal, while La³⁺ remains on the surface of TiO₂ without entering the crystal lattice. La/N/TiO₂-MAR demonstrates a higher specific surface area and enhanced light absorption capacity, which facilitates both adsorption and photocatalytic degradation. At the La³⁺ doping concentration of 0.05 M, La_0.05/N/TiO₂-MAR demonstrates optimal photocatalytic degradation performance, achieving an 85.36% removal rate of Rhodamine B after 240 min of visible-light exposure. Full article

(This article belongs to the Section Catalytic Materials)

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13 pages, 3182 KiB

Open AccessArticle

Improved Electrochemical Performance Using Transition Metal Doped ZnNi/Carbon Nanotubes as Conductive Additive in Li/CF_x Battery

by Fangmin Wang, Jiayin Li, Yuxin Zheng, Xue Dong, Yuzhen Zhao, Zemin He, Manni Li, Lei Lin, Danyang He, Zongcheng Miao, Haibo Zhang, Hua Tan and Jianfeng Huang

Catalysts 2025, 15(8), 758; https://doi.org/10.3390/catal15080758 - 8 Aug 2025

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Abstract

Lithium/carbon fluoride (Li/CF_x) batteries are promising for specialized applications due to their high theoretical capacity (>865 mAh·g⁻¹) and energy density. However, their practical deployment is hindered by the intrinsically low conductivity of CF_x and sluggish reaction kinetics. While [...] Read more.

Lithium/carbon fluoride (Li/CF_x) batteries are promising for specialized applications due to their high theoretical capacity (>865 mAh·g⁻¹) and energy density. However, their practical deployment is hindered by the intrinsically low conductivity of CF_x and sluggish reaction kinetics. While conventional conductive additives improve electron transport, their physical mixing with active materials yields weak interfacial contacts and fails to catalytically facilitate C–F bond cleavage. To address these dual limitations, this study proposes a dual-functional conductive-catalytic additive strategy. We engineered zinc-nickel/carbon nanotube (ZnNi/CNT) composites modified with transition metal dopants (Fe, W, Cu) to integrate conductive networks with nanoscale-dispersed catalytic sites. Fe-doped ZnNi/CNT (ZnFeNiC) emerged as the optimal system, delivering a discharge plateau of 2.45 V and a specific capacity of 810.3 mAh·g⁻¹ at 0.1 C. This performance is attributed to Fe-doping accelerates Li⁺ diffusion, and promotes reversible Ni redox transitions (Ni²⁺↔Ni⁰) that catalyze C–F bond dissociation. This work establishes a design paradigm for high-performance Li/CF_x batteries, bridging the gap between conductive enhancement and catalytic activation. Full article

(This article belongs to the Special Issue Tailored Nanosystems and Nanocatalysts for Photo-/Electrocatalytic Applications, 2nd Edition)

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20 pages, 2212 KiB

Open AccessArticle

ANCUT1, a Fungal Cutinase MgCl₂-Activated by a Non-Essential Activation Mechanism for Poly(ethylene terephthalate) Hydrolysis

by José Augusto Castro-Rodríguez, Karla Fernanda Ramírez-González, Francisco Franco-Guerrero, Andrea Sabido-Ramos, Ilce Fernanda Abundio-Sánchez, Rogelio Rodríguez-Sotres, Adela Rodríguez-Romero and Amelia Farrés

Catalysts 2025, 15(8), 757; https://doi.org/10.3390/catal15080757 - 7 Aug 2025

Viewed by 441

Abstract

Plastic waste, particularly poly(ethylene terephthalate) (PET), negatively impacts the environment and human health. Biotechnology could become an alternative to managing PET waste if enzymes ensure the recovery of terephthalic acid with efficiencies comparable to those of chemical treatments. Recent research has highlighted the [...] Read more.

Plastic waste, particularly poly(ethylene terephthalate) (PET), negatively impacts the environment and human health. Biotechnology could become an alternative to managing PET waste if enzymes ensure the recovery of terephthalic acid with efficiencies comparable to those of chemical treatments. Recent research has highlighted the potential of fungal cutinases, such as wild-type ANCUT1 (ANCUT1^wt) from Aspergillus nidulans, in achieving PET depolymerization. Fungal cutinases’ structures differ from those of bacterial cutinases, while their PET depolymerization mechanism has not been well studied. Here, a reliable model of the ANCUT1^wt was obtained using AlphaFold 2.0. Computational chemistry revealed potential cation-binding sites, which had not been described regarding enzymatic activation in fungal cutinases. Moreover, it allowed the prediction of residues with the ability to interact with a PET trimer that were mutation candidates to engineer the substrate binding cleft, seeking enhancements of PET hydrolysis. Enzyme kinetics revealed that both ANCUT1^wt and ANCUT1^N73V/L171Q (DM) were activated by MgCl₂, increasing the dissociation constant of the substrate and maximal reaction rate. We found that in the presence of MgCl₂, DM hydrolyzed different PET samples and released 9.1-fold more products than ANCUT1^wt. Scanning Electron Microscopy revealed a different hydrolysis mode of these enzymes, influenced by the polymer’s crystallinity and structure. Full article

(This article belongs to the Special Issue Catalysis Accelerating Energy and Environmental Sustainability)

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14 pages, 4144 KiB

Open AccessArticle

Biodegradation of Both Ethanol and Acetaldehyde by Acetobacter ghanensis JN01

by Hongyan Liu, Jingjing Wang, Qianqian Xu, Xiaoyu Cao, Xinyue Du, Kun Lin and Hai Yan

Catalysts 2025, 15(8), 756; https://doi.org/10.3390/catal15080756 - 7 Aug 2025

Viewed by 207

Abstract

Excessive alcohol consumption is associated with systemic health risks due to the production of acetaldehyde, a primary carcinogen that not only pollutes the environment but also endangers human health. In this study, a promising bacterial strain for biodegrading both ethanol and acetaldehyde was [...] Read more.

Excessive alcohol consumption is associated with systemic health risks due to the production of acetaldehyde, a primary carcinogen that not only pollutes the environment but also endangers human health. In this study, a promising bacterial strain for biodegrading both ethanol and acetaldehyde was successfully isolated from the traditional fermented food Jiaosu and identified as Acetobacter ghanensis JN01 based on average nucleotide identity (ANI) analysis. Initial ethanol of 1 g/L was completely biodegraded within 4 h, while initial acetaldehyde of 1 g/L was also rapidly removed at 2 or 1 h by whole cells or cell-free extracts (CEs) of JN01, respectively, which indicated that JN01 indeed has a strong ability in the biodegradation of both ethanol and acetaldehyde. Whole-genome sequencing revealed a 2.85 Mb draft genome of JN01 with 57.0% guanine–cytosine (GC) content and the key metabolic genes (adh1, adh2, and aldh) encoding involving alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), co-located with NADH dehydrogenase genes and ethanol-responsive regulatory motifs, supporting the metabolic pathway of transforming ethanol to acetaldehyde, and, subsequently, converting acetaldehyde to acetic acid. Furthermore, selected in vitro safety-related traits of JN01 were also assessed, which is very important in the development of microbial catalysts against both ethanol and acetaldehyde. Full article

(This article belongs to the Section Biocatalysis)

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18 pages, 3706 KiB

Open AccessArticle

Controllable Preparation of TiO₂/SiO₂@Blast Furnace Slag Fiber Composites Based on Solid Waste Carriers and Study on Mechanism of Photocatalytic Degradation of Urban Sewage

by Xinwen Luo, Jinhu Wu, Guangqian Zhu, Xinyu Han, Junjian Zhao, Yaqiang Li, Yingying Li and Shaopeng Gu

Catalysts 2025, 15(8), 755; https://doi.org/10.3390/catal15080755 - 7 Aug 2025

Viewed by 252

Abstract

Photocatalytic composite materials (TiO₂/SiO₂/BFSF) were first fabricated using the sol–gel method of loading SiO₂ and TiO₂ on blast furnace slag fibers (BFSFs) in sequence and using them as a new carrier. Then, TG-DTA, XRD, BET, SEM-EDS, and [...] Read more.

Photocatalytic composite materials (TiO₂/SiO₂/BFSF) were first fabricated using the sol–gel method of loading SiO₂ and TiO₂ on blast furnace slag fibers (BFSFs) in sequence and using them as a new carrier. Then, TG-DTA, XRD, BET, SEM-EDS, and UV-Vis absorption spectra, as well as spectrophotometric measurements, were employed to analyze the physicochemical properties of TiO₂. The influence of SiO₂ coating, the number of impregnations in TiO₂ sol, the calcination temperature, and the number of repeated usages on the activity of TiO₂/SiO₂/BFSF was researched by analyzing the degradation of methylene blue (MB) aqueous solution. The results show that SiO₂ could increase the load of TiO₂, impede the growth of TiO₂ grains, and inhibit the recombination of electron–hole pairs, ultimately enhancing the photocatalytic activity of samples. The activity of TiO₂/SiO₂/BFSF first quickly increased and then slowly decreased with an increase in the loading times of TiO₂ sol and calcination temperature. After three impregnations in TiO₂ sol and calcining at 450 °C for 2.5 h, a uniform and compact anatase TiO₂ thin film was deposited on the surface of TiO₂/SiO₂/BFSF, showing the strongest activity. When this sample was used to degrade MB aqueous solution for 180 min under ultraviolet light irradiation, the degradation proportion reached a maximum of 96%. After four reuses, the degradation ratio could still reach 67%. In addition, three potential photocatalytic mechanisms were proposed. Finally, the high-value-added application of blast furnace slag for preparing photocatalytic composite materials was achieved, successfully turning solid waste into “treasure”. Full article

(This article belongs to the Special Issue Enhanced Photocatalytic Activity over Ti, Zn, or Sn-Based Catalysts)

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13 pages, 2770 KiB

Open AccessArticle

Tribocatalytic Degradation of Organic Dyes by Disk-Shaped PTFE and Titanium: A Powder-Free Catalytic Technology for Wastewater Treatment

by Hanze Zhu, Zeren Zhou, Senhua Ke, Chenyue Mao, Jiannan Song and Wanping Chen

Catalysts 2025, 15(8), 754; https://doi.org/10.3390/catal15080754 - 7 Aug 2025

Viewed by 249

Abstract

Tribocatalysis is receiving more and more attention for its great potential in environmental remediation. In this study, a special tribocatalysis was explored as a powder-free catalytic technology for the degradation of organic dyes. Polytetrafluoroethylene (PTFE) and titanium (Ti) disks were first assembled as [...] Read more.

Tribocatalysis is receiving more and more attention for its great potential in environmental remediation. In this study, a special tribocatalysis was explored as a powder-free catalytic technology for the degradation of organic dyes. Polytetrafluoroethylene (PTFE) and titanium (Ti) disks were first assembled as magnetic rotary disks and then driven to rotate through magnetic stirring in dye solutions in beakers with PTFE, Ti, and Al₂O₃ disks coated on bottoms separately. PTFE and Ti generated dynamic friction with the disks on the beaker bottoms in the course of magnetic stirring, from which some interesting dye degradations resulted. Among those dynamic frictions generated, 40 mg/L rhodamine b (RhB), 30 mg/L methyl orange (MO), and 20 mg/L methylene blue (MB) were effectively degraded by the one between PTFE and PTFE, the one between Ti and Ti, and the one between PTFE and Ti, respectively. Hydroxyl radicals and superoxide radicals were detected for two frictions, one between PTFE and PTFE and the other between Ti and Ti. It is proposed that Ti in friction increases the pressure in blocked areas through deformation and then catalyzes reactions under high pressure. Mechano-radicals are formed by PTFE through deformation, and are responsible for dye degradation. This work demonstrates a powder-free tribocatalysis for organic pollutant degradation and suggests an especially eco-friendly catalytic technology to wastewater treatment. Full article

(This article belongs to the Special Issue Environmentally Friendly Catalysis for Green Future)

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13 pages, 3810 KiB

Open AccessArticle

Solar-Driven Selective Benzyl Alcohol Oxidation in Pickering Emulsion Stabilized by CNTs/GCN Hybrids Photocatalyst

by Yunyi Han, Yuwei Hou, Xuezhong Gong, Yu Zhang, Meng Wang, Pekhyo Vasiliy Ivanovich, Meili Guan and Jianguo Tang

Catalysts 2025, 15(8), 753; https://doi.org/10.3390/catal15080753 - 7 Aug 2025

Viewed by 342

Abstract

Herein, a bi-functional composite photocatalyst was synthesized by integrating carbon nanotubes (CNTs) and graphitic carbon nitride (GCN) via a facile electrostatic self-assembly strategy. The resulting CNTs/GCN composite served dual roles as both a solid emulsifier and a photocatalyst, enabling highly efficient photocatalytic benzyl [...] Read more.

Herein, a bi-functional composite photocatalyst was synthesized by integrating carbon nanotubes (CNTs) and graphitic carbon nitride (GCN) via a facile electrostatic self-assembly strategy. The resulting CNTs/GCN composite served dual roles as both a solid emulsifier and a photocatalyst, enabling highly efficient photocatalytic benzyl alcohol oxidation within a Pickering emulsion system. The relationship between emulsion droplet size and solid emulsifier dosage was investigated and optimized. The enhanced photocatalytic function was supported by an improved photocurrent response and reduced charge-transfer resistance, attributed to superior charge separation efficiency. Consequently, the benzyl alcohol conversion efficiency achieved in the Pickering emulsion system (58.9%) was three-fold of that observed in a traditional oil–water non-emulsion system (19.0%). Key active species were identified as photoholes, and an interfacial reaction mechanism was proposed. This work provides a new approach for extending photocatalytic applications in aqueous environments to diverse organic conversion reactions through the construction of multifunctional photocatalysts. Full article

(This article belongs to the Collection Catalysis in Advanced Oxidation Processes for Pollution Control)

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14 pages, 2584 KiB

Open AccessArticle

Enhanced Catalytic Ozonation of Formaldehyde over MOFs- Derived MnO_x Catalysts with Diverse Morphologies: The Role of Oxygen Vacancies

by Yulin Sun, Yiwei Zhang, Yong He, Wubin Weng, Yanqun Zhu and Zhihua Wang

Catalysts 2025, 15(8), 752; https://doi.org/10.3390/catal15080752 - 6 Aug 2025

Viewed by 346

Abstract

Metal–organic frameworks (MOFs) have become a hot topic in various research fields nowadays. And MOF-derived metal oxides prepared by the sacrificial template method have been widely applied as catalysts for pollutant removal. Accordingly, we prepared a series of MOF-derived MnO_x catalysts with [...] Read more.

Metal–organic frameworks (MOFs) have become a hot topic in various research fields nowadays. And MOF-derived metal oxides prepared by the sacrificial template method have been widely applied as catalysts for pollutant removal. Accordingly, we prepared a series of MOF-derived MnO_x catalysts with diverse morphologies (rod-like, flower-like, slab-like) via the pyrolysis of MOF precursors, and the as-prepared MnO_x catalysts demonstrated superior performance compared to the one prepared using the co-precipitation method. MnO_x-II, with a flower-like structure, exhibited excellent activity for formaldehyde (HCHO) catalytic ozonation at room temperature, reaching complete HCHO conversion at O₃/HCHO of 1.5 and more than 90% CO₂ selectivity at an O₃/HCHO ratio of 2.5. On the basis of various characterization methods, it was clarified that the enhanced catalytic performance of MnO_x-II benefited from its larger BET surface area, abundant oxygen vacancies, better redox ability at lower temperature, and more Lewis acid sites. The H₂O resistance and stability tests were also conducted. Furthermore, DFT calculations substantiated the enhanced adsorption of HCHO and O₃ on oxygen vacancies, while in–situ DRIFTS measurements elucidated the degradation pathway of HCHO during catalytic ozonation through detected intermediates. Full article

(This article belongs to the Special Issue Catalysis Accelerating Energy and Environmental Sustainability)

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21 pages, 6025 KiB

Open AccessArticle

Solar-Activated Titanium-Based Cu₄O₃/ZrO₂/TiO₂ Ternary Nano-Heterojunction for Rapid Photocatalytic Degradation of the Textile Dye Everzol Yellow 3RS

by Saira, Wesam Abd El-Fattah, Muhammad Shahid, Sufyan Ashraf, Zeshan Ali Sandhu, Ahlem Guesmi, Naoufel Ben Hamadi, Mohd Farhan and Muhammad Asam Raza

Catalysts 2025, 15(8), 751; https://doi.org/10.3390/catal15080751 - 6 Aug 2025

Viewed by 367

Abstract

Persistent reactive azo dyes released from textile finishing are a serious threat to water systems, but effective methods using sunlight to break them down are still limited. Everzol Yellow 3RS (EY-3RS) is particularly recalcitrant: past studies have relied almost exclusively on physical adsorption [...] Read more.

Persistent reactive azo dyes released from textile finishing are a serious threat to water systems, but effective methods using sunlight to break them down are still limited. Everzol Yellow 3RS (EY-3RS) is particularly recalcitrant: past studies have relied almost exclusively on physical adsorption onto natural or modified clays and zeolites, and no photocatalytic pathway employing engineered nanomaterials has been documented to date. This study reports the synthesis, characterization, and performance of a visible-active ternary nanocomposite, Cu₄O₃/ZrO₂/TiO₂, prepared hydrothermally alongside its binary (Cu₄O₃/ZrO₂) and rutile TiO₂ counterparts. XRD, FT-IR, SEM-EDX, UV-Vis, and PL analyses confirm a heterostructured architecture with a narrowed optical bandgap of 2.91 eV, efficient charge separation, and a mesoporous nanosphere-in-matrix morphology. Photocatalytic tests conducted under midsummer sunlight reveal that the ternary catalyst removes 91.41% of 40 ppm EY-3RS within 100 min, markedly surpassing the binary catalyst (86.65%) and TiO₂ (81.48%). Activity trends persist across a wide range of operational variables, including dye concentrations (20–100 ppm), catalyst dosages (10–40 mg), pH levels (3–11), and irradiation times (up to 100 min). The material retains ≈ 93% of its initial efficiency after four consecutive cycles, evidencing good reusability. This work introduces the first nanophotocatalytic strategy for EY-3RS degradation and underscores the promise of multi-oxide heterojunctions for solar-driven remediation of colored effluents. Full article

(This article belongs to the Special Issue Recent Advances in Photocatalysis for Environmental Applications)

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15 pages, 1040 KiB

Open AccessArticle

Alcalase Specificity by Different Substrate Proteins Under Different Conditions: The Enzyme Immobilization on Carrageenan Beads Strongly Affects the pH/Activity Curve Depending on the Substrate Protein

by Alan Portal D’Almeida, Pedro Abellanas-Perez, Luciana Rocha Barros Gonçalves, Tiago Lima de Albuquerque, Ivanildo José da Silva Junior and Roberto Fernandez-Lafuente

Catalysts 2025, 15(8), 750; https://doi.org/10.3390/catal15080750 - 5 Aug 2025

Viewed by 319

Abstract

Alcalase was immobilized–stabilized on carrageenan beads following a previously described protocol. Then, the activities of free and immobilized enzymes were compared using different protein substrates (casein, (CS), bovine serum albumin (BSA), or hemoglobin (HG)) at different pH values and temperatures. The observed activity [...] Read more.

Alcalase was immobilized–stabilized on carrageenan beads following a previously described protocol. Then, the activities of free and immobilized enzymes were compared using different protein substrates (casein, (CS), bovine serum albumin (BSA), or hemoglobin (HG)) at different pH values and temperatures. The observed activity depended on the substrate protein and enzyme formulation used. The highest enzyme activity could be observed at pHs 5, 7, or 10, depending on the substrate protein and the Alcalase formulation. The effect of the temperature at these pHs on the activity versus the different substrate proteins showed a common pattern. At low temperatures, the immobilized enzyme presented higher (mainly at acidic-neutral pH values and using BSA) or similar specific activity than the free enzyme. At temperatures near the optimal for the free enzyme, it became the most active, while at higher temperatures, the immobilized enzyme recovered the lead, although differences in the optimal temperature were not very significant. This may be explained by the lower mobility of the immobilized–stabilized enzyme. The immobilized enzyme could be much more active than the free enzyme or slightly less active, even using mild conditions, depending on the substrate protein, pH, and temperature used to determine the enzyme activity. Full article

(This article belongs to the Section Biocatalysis)

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15 pages, 4751 KiB

Open AccessFeature PaperArticle

Electrocatalytic Oxidation for Efficient Toluene Removal with a Catalytic Cu-MnO_x/GF Electrode in a Solid-State Electrocatalytic Device

by Haozhen Liu, Mingxin Liu, Xiqiang Zhao, Ping Zhou, Zhanlong Song, Wenlong Wang, Jing Sun and Yanpeng Mao

Catalysts 2025, 15(8), 749; https://doi.org/10.3390/catal15080749 - 5 Aug 2025

Viewed by 277

Abstract

A series of Cu-MnO_x/GF catalytic electrodes, with graphite felt (GF) pretreated via microwave modification as the catalyst carrier, were prepared under various hydrothermal conditions and characterized using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption, [...] Read more.

A series of Cu-MnO_x/GF catalytic electrodes, with graphite felt (GF) pretreated via microwave modification as the catalyst carrier, were prepared under various hydrothermal conditions and characterized using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption, and Raman spectroscopy. The catalytic oxidation activity of catalytic Cu-MnO_x/GF electrodes toward toluene was evaluated in an all-solid-state electrocatalytic device under mild operating conditions. The evaluation results demonstrated that the microwave-modified catalytic electrode exhibited high electrocatalytic activity toward toluene oxidation, with Cu-MnO_x/700W-GF exhibiting significantly higher catalytic activity, indicating that an increase in catalyst loading capacity can promote the removal of toluene. Only CO₂ and CO were detected, with no other intermediates observed in the reaction process. Moreover, the catalytic effect was significantly affected by the relative humidity. The catalytic oxidation of toluene can be fully realized under a certain humidity, indicating that the conversion of H₂O to strongly oxidizing ·OH on the catalytic electrode is a key step in this reaction. Full article

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

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14 pages, 4144 KiB

Open AccessArticle

Analysis and Application of UV-LED Photoreactors for Phenol Removal

by Betsabé Ildefonso-Ojeda, Macaria Hernández-Chávez, Mayra A. Álvarez-Lemus, Rosendo López-González, José R. Contreras-Bárbara, Karen Roa-Tort, Josué D. Rivera-Fernández and Diego A. Fabila-Bustos

Catalysts 2025, 15(8), 748; https://doi.org/10.3390/catal15080748 - 5 Aug 2025

Viewed by 316

Abstract

The development of three types of UV radiation-based photoreactors using light-emitting diodes (LEDs) is presented. In this work, three pattern irradiation arrangements, direct radiation, internal radiation, and external radiation, were tested for deactivation of a typical model contaminant in wastewater under the same [...] Read more.

The development of three types of UV radiation-based photoreactors using light-emitting diodes (LEDs) is presented. In this work, three pattern irradiation arrangements, direct radiation, internal radiation, and external radiation, were tested for deactivation of a typical model contaminant in wastewater under the same conditions. All photoreactors allow the adjustment of optical power and irradiation time and include a sensor for temperature monitoring in the solution. In this case, phenol was used as a model contaminant with TiO₂ as a photocatalyst in a batch-type reactor at pH 7. The results showed that the highest degradation efficiency was achieved after 120 min, reaching 97.79% for the internal-radiation photoreactor, followed by 90.17% when the direct-radiation photoreactor was used, and 85.24% for the external-radiation photoreactor. Phenol degradation served as the basis for validating reactor performance, given its persistence and relevance as an indicator in advanced oxidation processes. It was concluded that the arrangement of LEDs in each photoreactor significantly influences phenol degradation under the same reaction conditions. Full article

(This article belongs to the Special Issue Remediation of Natural Waters by Photocatalysis)

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12 pages, 2634 KiB

Open AccessArticle

Singlet Oxygen-Mediated Micropollutant Degradation Using an FePc-Modified CNT Filter via Peroxymonosulfate Activation

by Chenxin Xie, Yifan Ren and Yanbiao Liu

Catalysts 2025, 15(8), 747; https://doi.org/10.3390/catal15080747 - 5 Aug 2025

Viewed by 293

Abstract

Herein, we rationally designed a molecular catalytic filter for effective micropollutants decontamination via peroxymonosulfate (PMS) activation. Specifically, iron phthalocanine (FePc) molecules with defined Fe–N₄ coordination were immobilized onto carbon nanotubes (CNTs), forming a hybrid catalyst that integrated molecular precision with heterogeneous catalytic [...] Read more.

Herein, we rationally designed a molecular catalytic filter for effective micropollutants decontamination via peroxymonosulfate (PMS) activation. Specifically, iron phthalocanine (FePc) molecules with defined Fe–N₄ coordination were immobilized onto carbon nanotubes (CNTs), forming a hybrid catalyst that integrated molecular precision with heterogeneous catalytic properties. The resulting CNT-FePc filter achieved a 98.4% removal efficiency for bisphenol A (10 ppm) in a single-pass operation system, significantly outperforming the CNT/PMS system without FePc (41.6%). Additionally, the CNT-FePc/PMS system demonstrated remarkable resistance to performance inhibition by common water matrix components. Unlike typical radical-dominated PMS activation processes, mechanistic investigations confirmed that the CNT-FePc/PMS system selectively promoted singlet oxygen (¹O₂) generation as the primary oxidative pathway. Density functional theory (DFT) calculations revealed that PMS exhibited stronger adsorption on FePc (−3.05 eV) compared to CNT (−2.86 eV), and that FePc effectively facilitated O–O bond elongation in PMS, thereby facilitating ¹O₂ generation. Additionally, seed germination assays indicated a significant reduction in the biotoxicity of the treated effluents. Overall, this work presents a catalyst design strategy that merges molecular-level coordination chemistry with practical flow-through configuration, enabling rapid, selective, and environmentally benign micropollutant removal. Full article

(This article belongs to the Collection Advanced Catalysts for Wastewater Remediation Technologies)

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23 pages, 5217 KiB

Open AccessArticle

High-Performance Pd-Pt/α-MnO₂ Catalysts for the Oxidation of Toluene

by Ning Dong, Wenjin Wang, Xuelong Zheng, Huan Liu, Jingjing Zhang, Qing Ye and Hongxing Dai

Catalysts 2025, 15(8), 746; https://doi.org/10.3390/catal15080746 - 5 Aug 2025

Viewed by 287

Abstract

Herein, α-MnO₂-supported Pt-Pd bimetal (xPd-yPt/α-MnO₂; x and y are the weight loadings (wt%) of Pd and Pt, respectively; x = 0, 0.23, 0.47, 0.93, and 0.92 wt%; and y = 0.91, 0.21, [...] Read more.

Herein, α-MnO₂-supported Pt-Pd bimetal (xPd-yPt/α-MnO₂; x and y are the weight loadings (wt%) of Pd and Pt, respectively; x = 0, 0.23, 0.47, 0.93, and 0.92 wt%; and y = 0.91, 0.21, 0.46, 0.89, and 0 wt%) catalysts were prepared using the polyvinyl alcohol-protected NaBH₄ reduction method. The physicochemical properties of the catalysts were determined by means of various techniques and their catalytic activities for toluene oxidation were evaluated. It was found that among the xPd-yPt/α-MnO₂ samples, 0.93Pd-0.89Pt/α-MnO₂ showed the best catalytic performance, with the toluene oxidation rate at 156 °C (r_cat) and space velocity = 60,000 mL/(g h) being 6.34 × 10⁻⁴ mol/(g s), much higher than that of 0.91Pt/α-MnO₂ (1.31 × 10⁻⁴ mol/(g s)) and that of 0.92Pd/α-MnO₂ (6.13 × 10⁻⁵ mol/(g s)) at the same temperature. The supported Pd-Pt bimetallic catalysts possessed higher Mn³⁺/Mn⁴⁺ and O_ads/O_latt molar ratios, which favored the enhancement in catalytic activity of the supported Pd-Pt bimetallic catalysts. Furthermore, the 0.47Pd-0.46Pt/α-MnO₂ sample showed better resistance to sulfur dioxide poisoning. The partial deactivation of 0.47Pd-0.46Pt/α-MnO₂ was attributed to the formation of sulfate species on the sample surface, which covered the active site of the sample, thus decreasing its toluene oxidation activity. In addition, the in situ DRIFTS results demonstrated that benzaldehyde and benzoate were the intermediate products of toluene oxidation. Full article

(This article belongs to the Section Environmental Catalysis)

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19 pages, 3220 KiB

Open AccessReview

Integrated Technology of CO₂ Adsorption and Catalysis

by Mengzhao Li and Rui Wang

Catalysts 2025, 15(8), 745; https://doi.org/10.3390/catal15080745 - 5 Aug 2025

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Abstract

This paper discusses the integrated technology of CO₂ adsorption and catalysis, which combines adsorption and catalytic conversion, simplifies the traditional process, reduces energy consumption, and improves efficiency. The traditional carbon capture technology has the problems of high energy consumption, equipment corrosion, and [...] Read more.

This paper discusses the integrated technology of CO₂ adsorption and catalysis, which combines adsorption and catalytic conversion, simplifies the traditional process, reduces energy consumption, and improves efficiency. The traditional carbon capture technology has the problems of high energy consumption, equipment corrosion, and absorbent loss, while the integrated technology realizes the adsorption, conversion, and catalyst regeneration of CO₂ in a single reaction system, avoiding complex desorption steps. Through micropore confinement and surface electron transfer mechanism, the technology improves the reactant concentration and mass transfer efficiency, reduces the activation energy, and realizes the low-temperature and high-efficiency conversion of CO₂. In terms of materials, MOF-based composites, alkali metal modified oxides, and carbon-based hybrid materials show excellent performance, helping to efficiently adsorb and transform CO₂. However, the design and engineering of reactors still face challenges, such as the development of new moving bed reactors. This technology provides a new idea for CO₂ capture and resource utilization and has important environmental significance and broad application prospects. Full article

(This article belongs to the Special Issue Catalysis Accelerating Energy and Environmental Sustainability)

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16 pages, 11908 KiB

Open AccessArticle

A Quinary-Metallic High-Entropy Electrocatalyst with Driving of Cocktail Effect for Enhanced Oxygen Evolution Reaction

by Jing-Yi Lv, Zhi-Jie Zhang, Hao Zhang, Jun Nan, Zan Chen, Xin Liu, Fei Han, Yong-Ming Chai and Bin Dong

Catalysts 2025, 15(8), 744; https://doi.org/10.3390/catal15080744 - 5 Aug 2025

Viewed by 336

Abstract

The complex system of high-entropy materials makes it challenging to reveal the specific function of each site for oxygen evolution reaction (OER). Here, with nickel foam (NF) as the substrate, FeCoNiCrMo/NF is designed to be prepared by metal–organic frameworks (MOF) as a precursor [...] Read more.

The complex system of high-entropy materials makes it challenging to reveal the specific function of each site for oxygen evolution reaction (OER). Here, with nickel foam (NF) as the substrate, FeCoNiCrMo/NF is designed to be prepared by metal–organic frameworks (MOF) as a precursor under an argon atmosphere. XRD analysis confirms that it retains a partial MOF crystal structure (characteristic peak at 2θ = 11.8°) with amorphous carbon (peaks at 22° and 48°). SEM-EDS mapping and XPS demonstrate uniform distribution of Fe, Co, Ni, Cr, and Mo with a molar ratio of 27:24:30:11:9. Electrochemical test results show that FeCoNiCrMo/NF has excellent OER characteristics compared with other reference prepared samples. FeCoNiCrMo/NF has an overpotential of 285 mV at 100 mA cm⁻² and performs continuously for 100 h without significant decline. The OER mechanism of FeCoNiCrMo/NF further reveal that Co and Ni are true active sites, and the dissolution of Cr and Mo promote the conversion of active sites into MOOH following the lattice oxygen mechanism (LOM). The precipitation–dissolution equilibrium of Fe also plays an important role in the OER process. The study of different reaction sites in complex systems points the way to designing efficient and robust catalysts. Full article

(This article belongs to the Special Issue Non-Novel Metal Electrocatalytic Materials for Clean Energy)

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17 pages, 3442 KiB

Open AccessArticle

Generating Strongly Basic Sites on C/Fe₃O₄ Core–Shell Structure: Preparation of Magnetically Responsive Mesoporous Solid Strong Bases Catalysts

by Tiantian Li, Xiaowen Li, Guangxia Shi, Yajun Gao, Qiang Guan, Guodong Kang, Yizhi Zeng and Dingming Xue

Catalysts 2025, 15(8), 743; https://doi.org/10.3390/catal15080743 - 4 Aug 2025

Viewed by 345

Abstract

Novel solid strong base catalysts have attracted considerable attention in fine chemical synthesis owing to their unique advantages. In this work, a magnetic solid strong base catalyst with controlled morphology and porous carbon shell structure was successfully fabricated using low-cost carbon sources combined [...] Read more.

Novel solid strong base catalysts have attracted considerable attention in fine chemical synthesis owing to their unique advantages. In this work, a magnetic solid strong base catalyst with controlled morphology and porous carbon shell structure was successfully fabricated using low-cost carbon sources combined with Fe₃O₄ nanoparticles. KOH was used to introduce strong basic sites through ultrasonic-assisted impregnation. The carbon shell acted as a protective barrier to suppress detrimental interactions between basic species and the support while maintaining structural integrity after high-temperature activation without morphology degradation. The obtained K/C/Fe₃O₄ catalyst exhibits excellent catalytic performance and near-ideal superparamagnetic behavior. In the transesterification reaction for dimethyl carbonate (DMC) synthesis, the K/C/Fe₃O₄ catalyst provides superior performance than conventional solid base catalysts and maintains stable activity over six consecutive cycles. Notably, efficient solid–liquid separation was achieved successfully via magnetic separation, demonstrating practical applicability for the K/C/Fe₃O₄ catalyst. Full article

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

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