Catalysts

8 pages, 4170 KB

Open AccessArticle

Porous Ru-Doped Double Perovskite Oxide as a High-Performance Electrocatalyst for the Oxygen Evolution Reaction

by Junbo Wang, Zhijiao Wang, Qi Tang, Yin Zhang, Diaoyu Deng, Yang Wang and Kaiteng Wang

Catalysts 2026, 16(5), 461; https://doi.org/10.3390/catal16050461 - 15 May 2026

The oxygen evolution reaction (OER) constitutes a critical bottleneck in water electrolysis for hydrogen production owing to its sluggish four-electron transfer kinetics. Double perovskite oxides (A₂BB’O₆) have emerged as exceptional OER catalysts distinguished by their stable crystal frameworks and [...] Read more.

The oxygen evolution reaction (OER) constitutes a critical bottleneck in water electrolysis for hydrogen production owing to its sluggish four-electron transfer kinetics. Double perovskite oxides (A₂BB’O₆) have emerged as exceptional OER catalysts distinguished by their stable crystal frameworks and flexible active-site tunability. Crucially, the alternating ordering of B and B’ cations at octahedral positions creates a unique lattice enriched with oxygen vacancies. Leveraging these intrinsic structural advantages, we synthesized a porous Ru-doped double perovskite oxide Sr₂Fe_1.9Ru_0.1O_6-δ (SFRO-850) featuring increased oxygen vacancies via a sol–gel route. Electrochemical measurement shows that SFRO-850 exhibits outstanding OER activity with a low overpotential of 326 mV at a current density of 10 mA cm⁻² and a Tafel slope of 67.48 mV dec⁻¹, superior to the undoped material and its counterparts. The results validate the efficacy of the double perovskite framework as a superior platform for hosting catalytically active sites, offering a viable pathway toward high-performance, low-noble-metal-content OER catalysts. Full article

(This article belongs to the Section Electrocatalysis)

► Show Figures

Figure 1

17 pages, 4486 KB

Open AccessArticle

Tunable Zn-Doping Enhanced Fenton-like Reaction for Butyl Xanthate Degradation: Unveiling the Non-Radical Reaction Pathway

by Shaomeng Huang, Yiqing Xu, Feijian Jing, Liping Wang, Jiawen Sheng and Qiongqiong He

Catalysts 2026, 16(5), 460; https://doi.org/10.3390/catal16050460 - 14 May 2026

Abstract

In the process of pollutant degradation by activating peroxymonosulfate (PMS) with carbon-based Fenton-like catalysts containing Fe as the active site, the influence of Zn atoms on the system has rarely been studied. In this study, by regulating the introduction of Zn sources, Fe-Zn-C [...] Read more.

In the process of pollutant degradation by activating peroxymonosulfate (PMS) with carbon-based Fenton-like catalysts containing Fe as the active site, the influence of Zn atoms on the system has rarely been studied. In this study, by regulating the introduction of Zn sources, Fe-Zn-C and Fe-C catalysts were successfully synthesized for activating PMS to degrade butyl xanthate (BX). The degradation experiment results showed that compared to the Fe-C system, the doping of Zn increased the degradation rate of BX in the Fe-Zn-C system by 10.66%, reaching 91.19% within 120 min. Moreover, by optimizing the reaction conditions, the highest BX degradation efficiency of 96.54% was achieved within 30 min. Through instrumental analysis, Fe and Zn elements were found to exist on the surface of the catalysts in the form of Fe²⁺Fe³⁺₂O₄ and ZnO crystals, and the catalytic oxidation reaction was dominated by non-free radical pathways, including ¹O₂ and direct electron transfer pathways. No free radicals were produced during the reaction, and it was speculated that Zn atoms played the role of an electron bridge in the reaction system, mediating electron transfer and enhancing catalytic performance through their synergistic effect with Fe. Comprehensive stability evaluation indicated that Fe-Zn-C ensures continuous catalytic activity and ecological safety with a low dissolution rate in aqueous solution. This study provides a new approach for the design of Fenton-like catalysts and the induction of non-radical pathways. Full article

(This article belongs to the Special Issue Catalytic Materials for Hazardous Wastewater Treatment)

► Show Figures

Graphical abstract

14 pages, 7670 KB

Open AccessFeature PaperArticle

Direct Vapour–Solid Synthesis of Intermetallic Pt-Zn and Pt-Te Nanoparticles on Carbon: Enhanced Oxygen Reduction Through Te and Zn Incorporation

by Daniel Garstenauer, Lukas Sallfeldner, Ondřej Zobač, Franz Jirsa and Klaus W. Richter

Catalysts 2026, 16(5), 459; https://doi.org/10.3390/catal16050459 - 14 May 2026

Abstract

Intermetallic compounds represent a highly promising class of materials for catalytic applications due to their tuneable structure, composition, and electronic properties. In this study, we report a series of carbon black-supported intermetallic Pt-Te and Pt-Zn nanoparticles synthesized via a novel and facile direct [...] Read more.

Intermetallic compounds represent a highly promising class of materials for catalytic applications due to their tuneable structure, composition, and electronic properties. In this study, we report a series of carbon black-supported intermetallic Pt-Te and Pt-Zn nanoparticles synthesized via a novel and facile direct vapour–solid approach. Their catalytic performance toward the oxygen reduction reaction (ORR) in alkaline media was systematically investigated. Incorporation of Te or Zn into Pt/C significantly enhanced the intrinsic activity, as reflected by an increase in the limiting current density from −2.11 mA cm⁻² for Pt/C to up to −2.94 mA cm⁻² for Pt-Zn and −2.85 mA cm⁻² for Pt-Te systems, while maintaining similar half-wave potentials of 0.79 V vs. RHE and onset potentials around 0.90 V vs. RHE. This work provides a direct comparison of two intermetallic systems prepared under identical conditions, demonstrating how composition and crystal structure determine the catalytic activity and selectivity in the ORR. Full article

(This article belongs to the Special Issue Advances in Electrocatalytic Materials for Hydrogen Energy Technologies)

► Show Figures

Graphical abstract

18 pages, 1878 KB

Open AccessArticle

CO₂ Reduction in Structured Ni/Mayenite Catalytic System: A Methanation Test by Means of a Pre-Industrial Scaled Chemical Pilot Plant

by Giacomo Seccacini, Martina Fattobene, Leonardo Suraniti, Paola Russo and Mario Berrettoni

Catalysts 2026, 16(5), 458; https://doi.org/10.3390/catal16050458 - 13 May 2026

Abstract

The performance of a Mayenite-supported nickel-based catalyst were investigated by using an in-house-designed, assembled and set-up chemical pilot plant, which was developed to provide experimental insights relevant to industrial scale up. In particular, the proposed heterogeneous catalytic system was structured in mm-sized spheres [...] Read more.

The performance of a Mayenite-supported nickel-based catalyst were investigated by using an in-house-designed, assembled and set-up chemical pilot plant, which was developed to provide experimental insights relevant to industrial scale up. In particular, the proposed heterogeneous catalytic system was structured in mm-sized spheres and tested in a large-scale experiment, in a fixed-bed reactor for the CO₂ methanation process, and the results were compared with the output achieved with a Ni/alumina catalyst produced by an analogous route as the benchmark. The obtained findings highlighted the effective potential of the Mayenite structure supporting metallic active sites in promoting CO₂ reduction under the selected operating conditions (450 °C, 4 bar), along with long-term stability and high CH₄ selectivity. Moreover, the available experimental equipment was optimized to achieve accurate estimations of amounts of reaction by-product , as confirmed by the optimal agreement with the mass balance retrieved from the measured gaseous outlet composition. Such an achievement, notable for a large-scale chemical plant, plays a capital role in terms of industrial applications due to the critical impact of residual carbon and water in establishing the viability of innovative catalyst systems for the CO₂ recycling process. Full article

20 pages, 6493 KB

Open AccessArticle

Effects of Zeolite LTA Type and Humidity on Photocatalytic Ammonia Removal over TiO₂-Coated Supports

by HanBit Lee, JongHyeon Lee, HwanHee Choi, HwaYong Lee and YoungHee Kim

Catalysts 2026, 16(5), 457; https://doi.org/10.3390/catal16050457 - 13 May 2026

Abstract

Ammonia (NH₃) emissions from livestock facilities pose significant environmental challenges, particularly under high-humidity conditions where conventional adsorption efficiency significantly declines. This study investigates the photocatalytic removal of NH₃ using TiO₂-coated zeolite LTA supports (3A and 4A) under relative [...] Read more.

Ammonia (NH₃) emissions from livestock facilities pose significant environmental challenges, particularly under high-humidity conditions where conventional adsorption efficiency significantly declines. This study investigates the photocatalytic removal of NH₃ using TiO₂-coated zeolite LTA supports (3A and 4A) under relative humidity (RH) levels typical of farm environments. The composites were synthesized via controlled dip-coating cycles and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analyses. At 55% RH, zeolite 3A exhibited higher NH₃ removal efficiency than zeolite 4A, owing to its smaller pore size and superior intrinsic adsorption selectivity. However, adsorption-only systems underwent rapid deactivation over repeated cycles. While TiO₂ coatings enhanced the photocatalytic activity of both supports, zeolite 3A composites showed a more pronounced decline in efficiency over time. In contrast, at 95% RH, the TiO₂-coated zeolite 4A achieved superior photocatalytic efficiency and operational stability. This performance is attributed to the 4A framework’s greater water uptake and faster diffusion kinetics, which promoted the generation of hydroxyl (•OH) and hydroperoxyl (HO₂•) radicals under UV-A irradiation. These findings suggest that while TiO₂–zeolite 3A is effective at moderate humidity, TiO₂–zeolite 4A is more robust for high-humidity livestock environments, providing a sustainable strategy for effective NH₃ emission control. Full article

► Show Figures

Figure 1

31 pages, 125713 KB

Open AccessReview

Theoretical Insights and Design Strategies of Metal–Nitrogen–Carbon Catalysts for Electrochemical Nitrogen Reduction Reaction

by Jianhui Yi, Zi Wen and Qing Jiang

Catalysts 2026, 16(5), 456; https://doi.org/10.3390/catal16050456 - 13 May 2026

Abstract

Electrochemical nitrogen reduction reaction (NRR) is a sustainable and environmentally friendly method for ammonia synthesis, offering a promising alternative to the Haber–Bosch method. Despite its considerable potential, NRR is still plagued by a scarcity of efficient catalysts. Metal–nitrogen–carbon (M–N–C) catalysts exhibit unique advantages [...] Read more.

Electrochemical nitrogen reduction reaction (NRR) is a sustainable and environmentally friendly method for ammonia synthesis, offering a promising alternative to the Haber–Bosch method. Despite its considerable potential, NRR is still plagued by a scarcity of efficient catalysts. Metal–nitrogen–carbon (M–N–C) catalysts exhibit unique advantages in achieving excellent NRR performance. Theoretical calculations are crucial in understanding and guiding the design of M–N–C catalysts. Herein, we summarize the theoretical progress and rational designs of M–N–C catalysts for NRR. The fundamental mechanisms of NRR are introduced, and the activity, selectivity, and stability exhibited by the M–N–C catalysts are analyzed in depth. Additionally, several design strategies for M–N–C catalysts are provided, including adjusting the central metal atoms, regulating the coordinative environments, and applying computational data-driven approaches to optimize the structures of M–N–C catalysts. Finally, a summary and outlook of M–N–C catalysts for NRR are given. Full article

(This article belongs to the Special Issue Young Researchers in Electrocatalysis)

► Show Figures

Figure 1

17 pages, 21280 KB

Open AccessArticle

Low-Temperature Hydrodeoxygenation of Lignin Model Compounds over Defect-Engineered Nickel Catalysts

by Yanliang Yang, Yaoru Du, Yue Luo, Ying Duan, Dong Sui, Yunmeng Wang, Xuechuan Lv and Tianliang Lu

Catalysts 2026, 16(5), 455; https://doi.org/10.3390/catal16050455 - 13 May 2026

Abstract

Catalytic hydrodeoxygenation (HDO) of aromatic aldehydes represents a core research direction in the efficient utilization of lignin. In this study, a cost-effective catalyst was constructed by incorporating rich lattice defects into Ni nanoparticles. The catalyst was synthesized via a uniform precipitation method, employing [...] Read more.

Catalytic hydrodeoxygenation (HDO) of aromatic aldehydes represents a core research direction in the efficient utilization of lignin. In this study, a cost-effective catalyst was constructed by incorporating rich lattice defects into Ni nanoparticles. The catalyst was synthesized via a uniform precipitation method, employing urea as the precipitant. By introducing aluminum nitrate during the precipitation process, nickel was effectively segregated to inhibit its growth and the generation of well-crystallized, defect-free Ni nanoparticles, thereby generating a substantial quantity of defective Ni nanoparticles with abundant lattice defects. The catalyst was characterized using XRD, TEM, HRTEM, EDS line and mapping scanning, XPS and H₂-TPD, confirming the formation of Ni nanoparticles with a narrow size distribution of ~5 nm with numerous lattice defects. The hydrodeoxygenation of vanillin was employed to evaluate the catalyst’s activity, with investigations into the effects of Al content, solvents, temperature, H₂ pressure, and reaction time. The reaction was successfully conducted at 363 K in water. The catalyst demonstrated excellent hydrodeoxygenation activity across a series of other aromatic aldehyde compounds. Cycle experiments confirmed the catalyst’s stability, maintaining its activity over at least five consecutive uses. Full article

(This article belongs to the Special Issue 15th Anniversary of Catalysts—Catalysis for Biomass Conversion and Valorisation)

► Show Figures

Graphical abstract

20 pages, 4299 KB

Open AccessFeature PaperArticle

Regulating Oxygen Vacancies in Ultrasonic-Assisted Green-Synthesized Copper-Doped δ-MnO₂ Catalysts for Boosting Formaldehyde Oxidation

by Xiudan Tao, Xiaohan Yang, Fufen Li, Yuqing He, Chenhui Liu, Zhengjun Li and Nianhua Dan

Catalysts 2026, 16(5), 454; https://doi.org/10.3390/catal16050454 - 13 May 2026

Abstract

Oxygen vacancies play a crucial role in modulating the chemical and catalytic properties of metal oxide catalysts. Herein, quercetin was used as a green reducing agent to prepare Cu-doped MnO₂ (Cu-MnO₂) composite catalysts with varying Cu doping levels via an [...] Read more.

Oxygen vacancies play a crucial role in modulating the chemical and catalytic properties of metal oxide catalysts. Herein, quercetin was used as a green reducing agent to prepare Cu-doped MnO₂ (Cu-MnO₂) composite catalysts with varying Cu doping levels via an ultrasonically assisted strategy. The structure-activity relationships were systematically investigated using XRD, Raman, XPS, H₂-TPR, and O₂-TPD. Benefiting from optimized surface lattice defects induced by an appropriate Cu doping level, the Cu-MnO₂-2 sample, which exhibited the highest oxygen vacancy concentration, achieved a HCHO removal efficiency of 99.2% for 1 ppm HCHO at room temperature (25 °C) and 50% relative humidity within 30 min. The enrichment of Mn³⁺, Cu⁺, and surface-adsorbed oxygen species (O_ads) further corroborated the increased oxygen vacancy density, indicating that moderate Cu doping effectively promotes electron transfer and oxygen activation. After five consecutive cycles, the HCHO conversion remained above 96%. Post-cycling characterizations (XRD, FTIR, EDS, and XPS) confirmed the excellent structural and chemical stability of the catalyst, with the Mn³⁺ proportion and Cu⁺/Cu²⁺ ratio well preserved. In situ DRIFTS analysis revealed that surface-adsorbed oxygen and oxygen-vacancy-activated reactive oxygen species (ROS) are key factors in the efficient HCHO oxidation over the green Cu-MnO₂-2 catalyst, promoting rapid conversion of intermediates and ultimately generating CO₂ and H₂O. This study provides a facile, low-cost, and green synthesis strategy for Cu-MnO₂ composite catalysts for indoor, room-temperature HCHO abatement, offering new insights into the design of other composite catalyst materials. Full article

(This article belongs to the Special Issue Metal and Non-Metal Doping Modification of Catalysts)

10 pages, 1082 KB

Open AccessFeature PaperArticle

Exploring β-Myrcene Incorporation in Propene Copolymerization Using Half-Titanocene Catalysts

by Kantarattana Paramanurak, Adriano Vignali, Benedetta Palucci, Fabio Bertini, Kotohiro Nomura and Simona Losio

Catalysts 2026, 16(5), 453; https://doi.org/10.3390/catal16050453 - 13 May 2026

Abstract

The development of polyolefin from bio-renewables has been considered an important subject in terms of circular economy. In this study, exploring the possibility of β-myrcene (MY) incorporation in propene copolymerization has been studied in the presence of various catalysts: phenoxide-modified half-titanocene, Cp’TiCl₂ [...] Read more.

The development of polyolefin from bio-renewables has been considered an important subject in terms of circular economy. In this study, exploring the possibility of β-myrcene (MY) incorporation in propene copolymerization has been studied in the presence of various catalysts: phenoxide-modified half-titanocene, Cp’TiCl₂(O-2,6-ⁱPr₂-4-C₆H₃) [Cp’ = Cp* (C₅Me₅), Me₃SiC₅H₄], and ketimide-modified half-titanicene, Cp’TiCl₂(N=C^tBu₂) (Cp’ = Cp*, Cp). Among the complexes tested, the permethylated Cp* catalysts, Cp*TiCl₂(O-2,6-ⁱPr₂-4-C₆H₃) and Cp*TiCl₂(N=C^tBu₂), exhibited moderate catalytic activities in the copolymerizations, affording the copolymers up to 3 mol% MY incorporation. The other catalysts showed negligible activity in the attempted copolymerizations. The resulting copolymers were amorphous and possessed sole glass transition temperatures (T_g), suggesting uniform compositions; the T_g values decreased with increasing comonomer (MY) content, reaching values as low as −17 °C. The results introduce valuable insights into the structure–property relationships of myrcene-based copolymers and pave the way for the future designs of tailored molecular catalysts for the synthesis of biobased elastomers. Full article

(This article belongs to the Special Issue 15th Anniversary of Catalysts: Shaping a Sustainable Future Through Catalysis)

► Show Figures

Graphical abstract

17 pages, 4064 KB

Open AccessArticle

High-Value Utilization of Waste Drilling Mud to Synthesize MFI Zeolite

by Jingang Zhao, Guanchao Wang, Taoyang Zou, Yuekun Jing and Fang Liu

Catalysts 2026, 16(5), 452; https://doi.org/10.3390/catal16050452 - 13 May 2026

Abstract

While the petroleum industry undergoes structural adjustments in supply and demand alongside a green and low-carbon transition, water drilling mud generated during oil extraction poses severe environmental challenges. Consequently, addressing the solid waste pollution and disposal issues associated with drilling mud has become [...] Read more.

While the petroleum industry undergoes structural adjustments in supply and demand alongside a green and low-carbon transition, water drilling mud generated during oil extraction poses severe environmental challenges. Consequently, addressing the solid waste pollution and disposal issues associated with drilling mud has become critical. In this study, ZSM-5 zeolite was synthesized using water drilling mud as a silicon and aluminum source, inexpensive n-butylamine as a template agent, and a combined approach of alkali-melting activation pre-treatment and seed-directed hydrothermal synthesis. By adjusting key parameters such as water content, template agent dosage, and seed addition, optimal synthesis conditions were determined. Based on these conditions, a series of ZSM-5 zeolites with varying silicon-to-aluminum ratios were synthesized. Characterization results from XRD, TEM, SEM, and N₂ adsorption–desorption experiments revealed that all prepared samples exhibited high crystallinity, regular morphology, and high specific surface area. ²⁷Al MAS NMR results indicated that almost aluminum species were located at the framework structures with four-coordination. In the 1,3,5-triisopropylbenzene cracking reaction, the conversion rate increased with decreasing silicon-to-aluminum ratio, consistent with variations in acid amount. These findings achieve high-value utilization of waste drilling mud, offering a novel pathway for low-cost synthesis of high-performance ZSM-5 zeolite. This breakthrough injects fresh momentum into the petroleum refining industry’s green sustainable development, fostering a win–win scenario that harmonizes ecological conservation with industrial profitability. Full article

► Show Figures

Figure 1

18 pages, 1892 KB

Open AccessArticle

P,N-Codoped Carbon for Efficient 2,5-Diformylfuran Production from Fructose

by Hao Luo, Qiao Dai, Ting Mo, Yunye Wang, Chenghao Lei, Meihong Wu and Xuemei Liao

Catalysts 2026, 16(5), 451; https://doi.org/10.3390/catal16050451 - 12 May 2026

Abstract

This study presents an approach for the “one-pot two-step” synthesis of 2,5-diformylfuran (DFF) from fructose using a metal-free phosphorus-doped carbon nitride (P-CN) catalyst. The bifunctional P-CN integrates P-O bonds for acid-catalyzed fructose dehydration to 5-hydroxymethylfurfural (HMF) and P-C/graphitic-N sites for selective aerobic HMF [...] Read more.

This study presents an approach for the “one-pot two-step” synthesis of 2,5-diformylfuran (DFF) from fructose using a metal-free phosphorus-doped carbon nitride (P-CN) catalyst. The bifunctional P-CN integrates P-O bonds for acid-catalyzed fructose dehydration to 5-hydroxymethylfurfural (HMF) and P-C/graphitic-N sites for selective aerobic HMF oxidation to DFF. The 10% P-CN catalyst achieved 91.5% DFF yield during the stepwise oxidation of isolated HMF under the mild conditions (1.5 MPa O₂, 120 °C), while the “one-pot” cascade reaction yielded 63% DFF due to competing side reactions. Characterization revealed that P-doping enhanced porosity (883 m²/g surface area) and electronic properties, with graphitic-N facilitating O₂ activation. P=O groups are hypothesized to mediate proton transfer from reactive substrates via hydrogen-bonding networks, thereby enhancing acid-catalyzed pathways. NH₃-TPD and XPS confirmed tailored acid sites and P-N/C elemental synergism, while FT-IR demonstrated substrate adsorption via P=O/HMF-OH interactions. The catalyst retained stability over multiple cycles, demonstrating its practicality. This work advances biomass valorization by elucidating the dual-role design of nonmetallic catalysts, offering an eco-friendly alternative to conventional metal-based systems. Full article

31 pages, 1620 KB

Open AccessReview

Microwave-Assisted Biomass Pyrolysis to Hydrocarbons: A Review of Catalyst Evolution from Single-Function to Multi-Site Composites

by Shengxian Xian, Jiurun Liu and Qing Xu

Catalysts 2026, 16(5), 450; https://doi.org/10.3390/catal16050450 - 12 May 2026

Abstract

Microwave-assisted pyrolysis (MAP) has emerged as a revolutionary technology for converting solid waste into high-value hydrocarbons. However, conventional pyrolysis and traditional single-function catalysts often face an inevitable “performance trade-off” involving severe mass transfer resistance, poor microwave absorption, and rapid coking. This review systematically [...] Read more.

Microwave-assisted pyrolysis (MAP) has emerged as a revolutionary technology for converting solid waste into high-value hydrocarbons. However, conventional pyrolysis and traditional single-function catalysts often face an inevitable “performance trade-off” involving severe mass transfer resistance, poor microwave absorption, and rapid coking. This review systematically summarizes the recent evolution of catalyst design toward advanced multi-site composites. It highlights the synergistic mechanisms of integrating microwave-responsive cores, hierarchical pore networks, and metal-acid bifunctional sites to achieve ultrafast localized heat transfer, targeted bond cleavage, and in-situ coking suppression. Furthermore, this paper critically examines current bottlenecks in scaling MAP to industrial levels. To address these challenges, we discuss emerging solutions, including hydrogen-enriched co-pyrolysis, non-destructive in-situ regeneration, and the integration of machine learning frameworks for intelligent process optimization. Full article

(This article belongs to the Special Issue Advanced Heterogeneous Catalysts for Sustainable Chemical Transformations: From Biomass Valorization to Clean Energy)

23 pages, 3776 KB

Open AccessArticle

Catalytic Enhancement of Biodiesel Combustion via Nano Boron Oxide (B₂O₃): Experimental and RSM-Based Analysis in a CI Engine

by Arif Savaş, Samet Uslu, Gonca Uslu, Oğuzhan Der, Ali Erçetin and Ramazan Şener

Catalysts 2026, 16(5), 449; https://doi.org/10.3390/catal16050449 - 12 May 2026

Abstract

The catalytic modification of combustion processes using nanoparticle additives has emerged as a promising strategy to improve fuel oxidation and reduce pollutant formation in compression ignition (CI) engines. In this study, the catalytic effects of nano-sized boron oxide (B₂O₃) [...] Read more.

The catalytic modification of combustion processes using nanoparticle additives has emerged as a promising strategy to improve fuel oxidation and reduce pollutant formation in compression ignition (CI) engines. In this study, the catalytic effects of nano-sized boron oxide (B₂O₃) on biodiesel combustion were systematically investigated. Jojoba oil, a non-edible and drought-resistant feedstock, was transesterified to produce second-generation biodiesel and blended with diesel fuel. Among the tested blends, J10 (10% biodiesel and 90% diesel) was selected as the base fuel blend due to its favorable combustion and emission characteristics. To explore catalytic enhancement mechanisms, B₂O₃ nanoparticles were introduced at concentrations of 25, 50, and 75 ppm. The high surface area and oxygen buffering capacity of B₂O₃ nanoparticles are expected to enhance oxidation reactions and promote radical formation during combustion. This catalytic effect contributes to improved combustion efficiency, as evidenced by a significant reduction in incomplete combustion products. Compared with diesel fuel (D100), HC emissions were reduced by up to 53.34%, while CO emissions decreased by 24.42–41.98% depending on the operating conditions and fuel blends. In addition, a noticeable improvement in combustion quality was reflected in the brake thermal efficiency (BTE), where variations of up to 11.61% were observed across different fuel blends. Response Surface Methodology (RSM) was employed to quantify the interaction between nanoparticle concentration and engine load and to identify optimal catalytic operating conditions. The optimal parameters were determined as 12.14 ppm B₂O₃ and 1.36 kW load, yielding a desirability of 0.7128. Under these conditions, the engine achieved a BSFC of 458.83 g/kWh and BTE of 22.01%, with emissions reduced to 0.041% CO, 14.29 ppm HC, and 346.44 ppm NO_x. The results demonstrate that nano B₂O₃ functions as a combustion catalyst by enhancing oxidation pathways and improving fuel-air interaction, thereby increasing combustion efficiency and reducing harmful emissions. Full article

(This article belongs to the Special Issue Catalysis for Sustainable Energy: Biodiesel and Biolubricant Innovations)

► Show Figures

Figure 1

14 pages, 18488 KB

Open AccessFeature PaperArticle

Engineering Oxidative Active Species Selectivity via Multi-Atom Doping: A 100% Singlet Oxygen Pathway in Peroxymonosulfate Activation

by Shaomeng Huang, Jiawen Sheng, Yiqing Xu, Liping Wang, Feijian Jing and Qiongqiong He

Catalysts 2026, 16(5), 448; https://doi.org/10.3390/catal16050448 - 12 May 2026

Abstract

¹O₂ has significant advantages over free radicals in Fenton-like reactions, but the induction of a single ¹O₂ reaction pathway is challenging and is often accompanied by free radical reactions and direct electron transfer pathways. In this study, Zn-O-C/N and [...] Read more.

¹O₂ has significant advantages over free radicals in Fenton-like reactions, but the induction of a single ¹O₂ reaction pathway is challenging and is often accompanied by free radical reactions and direct electron transfer pathways. In this study, Zn-O-C/N and Zn-S/O-C/N catalysts were synthesized by controlling the doping of the S element, and the single ¹O₂ reaction pathway was successfully induced. Furthermore, Zn-O-C/N performed better than the Zn-S/O-C/N system, with higher phenanthrene (PHE) degradation rates of 76.14% compared to 62.86%. And Zn-O-C/N can achieve a maximum degradation rate of 85.62% under the developed optimization condition. The characterization results revealed that the ZnO active sites are located on the surface of the Zn-O-C/N catalyst and participate in electron mediation together with C-N. ZnS was generated with the doping of S, speculating that a large amount of ZnS with low catalytic activity is generated and occupies the active sites, thereby inhibiting the catalytic activity. Additionally, only ¹O₂ was generated in the two systems, without the formation of free radicals and the occurrence of direct electron transfer reaction. However, the Zn-O-C/N catalyst has been proven to have strong stability and a low amount of dissolution, demonstrating environmental safety. This study confirmed the inhibitory effect of S on the activity of the Zn-O-C/N system and provided a synthesis strategy for the catalyst design, which can only induce the ¹O₂ reaction pathway. Full article

► Show Figures

Graphical abstract

34 pages, 2511 KB

Open AccessReview

Advanced ZnO Nanorods and Metal–Organic Frameworks for Sustainable Photocatalytic Microplastic Degradation

by Mani Sivakumar, Ganeshraja Ayyakannu Sundaram and Junhu Wang

Catalysts 2026, 16(5), 447; https://doi.org/10.3390/catal16050447 - 12 May 2026

Abstract

The increasing presence of microplastics in the aquatic and terrestrial food chains calls for the need to come up with innovative and effective remediation approaches. Such innovations as zinc oxide (ZnO) structures and metal–organic frameworks (MOFs) are examined as the second generation of [...] Read more.

The increasing presence of microplastics in the aquatic and terrestrial food chains calls for the need to come up with innovative and effective remediation approaches. Such innovations as zinc oxide (ZnO) structures and metal–organic frameworks (MOFs) are examined as the second generation of photocatalysts for degrading microplastics under sunlight. We will focus on the latest advances and discuss the structure of photocatalytic processes, their functioning under various light conditions, and their environmental impacts, especially environmental safety and ecotoxicity. ZnO structures are even better photocatalysts because they form reactive oxygen species (ROS) as good as other metal oxides. However, their possible cytotoxicity and the ability to generate oxidative stress require serious evaluation. MOFs, on the contrary, offer physicochemical properties, environmental safety, ecotoxicity, and environmentally friendly synthesis pathways, making them a worthy substitute. The review underscores the urgency of incorporating environmental safety and ecotoxicity into the design of photocatalysts, thereby unlocking their full potential while avoiding environmental or human health risks. Moving forward in the field of sustainable nanotechnology to remove microplastics will provide the way to come up with green innovations and hence guarantee the effectiveness of combating plastic pollution in long-term stability. Full article

(This article belongs to the Special Issue Catalysts and Plastics: From Degradation to Functional Applications)

► Show Figures

Graphical abstract

31 pages, 9310 KB

Open AccessArticle

Methanol Steam Reforming on Ru/m-ZrO₂: Sodium Promotion of the CO₂-Forming Pathway

by Nadia ALHirbawi, Amélie Enciso Juarez, Michela Martinelli, Savana R. Alt, A. Jeremy Kropf, Donald C. Cronauer and Gary Jacobs

Catalysts 2026, 16(5), 446; https://doi.org/10.3390/catal16050446 - 11 May 2026

Abstract

Sodium (Na) promotion of Ru/m-ZrO₂ was investigated to elucidate how an alkali modification tunes selectivity in methanol steam reforming (MSR). H₂-TPR/XANES/EXAFS show that Na increases surface basicity and strengthens Ru–O interactions, shifting RuO_x reduction and H₂ spillover to [...] Read more.

Sodium (Na) promotion of Ru/m-ZrO₂ was investigated to elucidate how an alkali modification tunes selectivity in methanol steam reforming (MSR). H₂-TPR/XANES/EXAFS show that Na increases surface basicity and strengthens Ru–O interactions, shifting RuO_x reduction and H₂ spillover to a higher temperature. DRIFTS reveals Na-induced red shifts of the formate ν(CH) band and changes in OCO vibrational splitting, consistent with weakening of the formate C–H bond and an altered binding geometry. CO₂-TPD confirms a monotonic shift toward stronger basic sites with increasing Na concentrations. Under MSR conditions, Na selectively increases CO₂ concentration at the expense of CO. At ~80% conversion and 325 °C, CO₂ selectivity increases from 12.0% (unpromoted) to 16.2, 21.0, and 26.5% for 0.5, 1.0, and 1.8% Na, respectively; at ~300 °C and ~66–69% conversion, CO₂ selectivity increases from 8.6% to 23.7% at 1.8% Na. Transient MSR experiments further show earlier and larger H₂ evolution upon Na addition, corroborating the promotion of the dehydrogenation/decarbonylation route to CO₂ + H₂. We propose that Na increases basicity and modifies the Ru–support interface to favor formate dehydrogenation/decarboxylation, thereby increasing the H₂ yield and lowering CO formation. Ru’s higher-energy, less occupied d-band stabilizes CO and oxygenated intermediates more strongly in the reforming environment, making the CO-forming pathway more resistant to suppression than on Pt. Full article

► Show Figures

Figure 1

17 pages, 12480 KB

Open AccessArticle

One-Pot Synthesis of Structurally Tunable Ag@Fe₃O₄ Nanoreactors for Ultra-Efficient and Magnetically Recyclable Reduction of 4-Nitrophenol

by Sihui Song, Chunting Li, Sadaf Mutahir, Muhammad Asim Khan and Feng Yan

Catalysts 2026, 16(5), 445; https://doi.org/10.3390/catal16050445 - 11 May 2026

Abstract

The catalytic reduction of toxic 4-Nitrophenol (4-NP) to valuable 4-aminophenol is highly important for environmental remediation. However, developing catalysts with high activity, good recyclability, and facile preparation remains challenging. Herein, Ag@Fe₃O₄ nanocomposites were controllably synthesized with a facile one-pot polyol [...] Read more.

The catalytic reduction of toxic 4-Nitrophenol (4-NP) to valuable 4-aminophenol is highly important for environmental remediation. However, developing catalysts with high activity, good recyclability, and facile preparation remains challenging. Herein, Ag@Fe₃O₄ nanocomposites were controllably synthesized with a facile one-pot polyol method. By varying the Ag:Fe precursor ratio, the structure could be tuned from dense and porous core-shell to Janus architectures. The porous Ag@Fe₃O₄ nanoreactors (Ag:Fe-0.4) exhibited exceptional catalytic performance, achieving complete 4-NP reduction within 75 s, with an apparent rate constant (k) of 6.29 × 10⁻² s⁻¹, a normalized rate constant (k_n) of 3742 s⁻¹ mmol⁻¹, and a TOF value of 1042 h⁻¹. XPS results verified that the excellent activity originated from the porous structure and interfacial charge transfer from Ag to Fe₃O₄. The catalysts showed super-paramagnetism and could be reused for at least eight cycles with >95% conversion retained. It also displayed high efficiency in reducing diverse nitroaromatics and in natural water. This work highlights the significance of structural and electronic modulation, providing a scalable strategy for magnetically recyclable catalysts toward environmental remediation and heterogeneous catalysis. Full article

(This article belongs to the Section Nanostructured Catalysts)

► Show Figures

Figure 1

17 pages, 16699 KB

Open AccessArticle

DFT-Assisted Machine Learning for Global Optimization of Fe–Carbon Catalyst: Persulfate Activation and Targeted Removal of Emerging Contaminants

by Changchun Yan, Zhiqiang Xu, Dingming Xue, Jiaqing Wang, Xiaochen Lin, Hao Zhou, Bing Ma and Houhu Zhang

Catalysts 2026, 16(5), 444; https://doi.org/10.3390/catal16050444 - 11 May 2026

Abstract

Fe–carbon catalysts (FCCs) are extensively used for persulfate activation in advanced oxidation processes (PS-AOPs), an approach regarded as an efficient and cost-effective strategy for removing emerging contaminants (ECs). However, the quantitative structure–activity relationship between the degradation efficiency of ECs with diverse molecular characteristics [...] Read more.

Fe–carbon catalysts (FCCs) are extensively used for persulfate activation in advanced oxidation processes (PS-AOPs), an approach regarded as an efficient and cost-effective strategy for removing emerging contaminants (ECs). However, the quantitative structure–activity relationship between the degradation efficiency of ECs with diverse molecular characteristics and the microstructure of FCCs has not been clearly elucidated. This hinders the widespread practical implementation of FCCs. Herein, density functional theory (DFT)-derived molecular-descriptor-assisted machine learning models were employed to accurately predict the reaction rate constants for EC degradation in FCC-PS AOPs, mainly focusing on three aspects: performance prediction, operating condition optimization and mechanism interpretation. Additionally, DFT-derived descriptors are integrated with fabrication and operational parameters to facilitate the generative design of FCCs. The excellent fitting performance of the overall XGB model in predicting the reaction constants for EC degradation (Test R² = 0.813) highlights the notable advantages of customized hyperparameter tuning for improving predictive accuracy. Subsequently, the submodels trained using different EC clusters (derived from t-SNE and K-means clustering methods) can offer specific strategies for selecting optimal parameters of FCC-PS AOPs that target ECs with distinct properties. The interpretability of the model was improved by using SHAP values and partial-dependence plots to clarify the internal relationships of the ML “black box”. Overall, a feasible and generalizable ML model is proposed to facilitate a paradigm shift in the inverse design of FCCs for the degradation of specific ECs. Full article

(This article belongs to the Special Issue Synthesis and Catalytic Applications of Advanced Porous Materials, 2nd Edition)

► Show Figures

Figure 1

15 pages, 9627 KB

Open AccessArticle

Boron-Doped Diamond Anode-Driven Electrochemical Oxidization of Fluorinated Firefighting Wastewater-Contaminated Groundwater

by Qi Wang, Gongjie Hua, Aiguo Gu, Jie Zou and Kuangfei Lin

Catalysts 2026, 16(5), 443; https://doi.org/10.3390/catal16050443 - 10 May 2026

Abstract

Per- and polyfluoroalkyl substances (PFASs) in fluorinated firefighting wastewater (FFW), which are difficult to remediate using conventional technologies, represent a critical environmental hazard due to the extreme persistence and bioaccumulation potential of soil–groundwater systems. Niobium-supported boron-doped diamond (BDD) anodes were synthesized by microwave [...] Read more.

Per- and polyfluoroalkyl substances (PFASs) in fluorinated firefighting wastewater (FFW), which are difficult to remediate using conventional technologies, represent a critical environmental hazard due to the extreme persistence and bioaccumulation potential of soil–groundwater systems. Niobium-supported boron-doped diamond (BDD) anodes were synthesized by microwave plasma chemical vapor deposition, and their performance in the electrochemical advanced oxidation processes (EAOPs) of FFW were systematically investigated. Under optimized conditions (100 mM Na₂SO₄ electrolyte with 100 mM peroxymonosulfate (PMS), current density of 33.3 mA/cm², pH = 6), the BDD anode achieved near-complete mineralization, with 92.5% total organic carbon (TOC) removal and significant defluorination (77.5% F⁻ release) within 240 min in simulated FFW-contaminated groundwater. For FFW-contaminated soil remediation, 90.2% TOC removal and 41.6% defluorination were achieved after 720 min under optimal treatment (water-to-soil ratio of 20:1). Quenching experiments and electron paramagnetic resonance (EPR) tests revealed that hydroxyl radicals (·OH) and singlet oxygen (¹O₂) were the predominant reactive species. Liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) analysis indicated that PFASs were removed by shortened carbon chains, ultimately mineralizing to CO₂ and F⁻. Toxicity assessment using Vibrio fischeri luminescence demonstrated a reduction in toxicity (from 99.8% to 20.9%), confirming the effective detoxification of BDD-based EAOPs. This work establishes BDD-based EAOPs as a promising technology for eliminating PFASs in groundwater and soil, offering theoretical insights into EAOPs and engineering solutions for PFAS remediation. Full article

(This article belongs to the Section Electrocatalysis)

► Show Figures

Figure 1

Journal Description

Catalysts

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI