Catalysts

21 pages, 4270 KiB

Open AccessArticle

Electrocatalytic Pathways and Efficiency of Cuprous Oxide (Cu₂O) Surfaces in CO₂ Electrochemical Reduction (CO₂ER) to Methanol: A Computational Approach

by Zubair Ahmed Laghari, Wan Zaireen Nisa Yahya, Sulafa Abdalmageed Saadaldeen Mohammed and Mohamad Azmi Bustam

Catalysts 2025, 15(2), 130; https://doi.org/10.3390/catal15020130 - 29 Jan 2025

Abstract

Carbon dioxide (CO₂) can be electrochemically, thermally, and photochemically reduced into valuable products such as carbon monoxide (CO), formic acid (HCOOH), methane (CH₄), and methanol (CH₃OH), contributing to carbon footprint mitigation. Extensive research has focused on catalysts, [...] Read more.

Carbon dioxide (CO₂) can be electrochemically, thermally, and photochemically reduced into valuable products such as carbon monoxide (CO), formic acid (HCOOH), methane (CH₄), and methanol (CH₃OH), contributing to carbon footprint mitigation. Extensive research has focused on catalysts, combining experimental approaches with computational quantum mechanics to elucidate reaction mechanisms. Although computational studies face challenges due to a lack of accurate approximations, they offer valuable insights and assist in selecting suitable catalysts for specific applications. This study investigates the electrocatalytic pathways of CO₂reduction on cuprous oxide (Cu₂O) catalysts, utilizing the computational hydrogen electrode (CHE) model based on density functional theory (DFT). The electrocatalytic performance of flat Cu₂O (100) and hexagonal Cu₂O (111) surfaces was systematically analysed, using the standard hydrogen electrode (SHE) as a reference. Key parameters, including free energy changes (ΔG), adsorption energies (E_ads), reaction mechanisms, and pathways for various intermediates were estimated. The results showed that CO₂ was reduced to CO_(g) on both Cu₂O surfaces at low energies. However, methanol (CH₃OH) production was observed preferentially on Cu₂O (111) at ΔG = −1.61 eV, whereas formic acid (HCOOH) and formaldehyde (HCOH) formation were thermodynamically unfavourable at interfacial sites. The CO₂-to-methanol conversion on Cu₂O (100) exhibited a total ΔG of −3.38 eV, indicating lower feasibility compared to Cu₂O (111) with ΔG = −5.51 eV. These findings, which are entirely based on a computational approach, highlight the superior catalytic efficiency of Cu₂O (111) for methanol synthesis. This approach also holds the potential for assessing the catalytic performance of other transition metal oxides (e.g., nickel oxide, cobalt oxide, zinc oxide, and molybdenum oxide) and their modified forms through doping or alloying with various elements. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion, 2nd Edition)

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11 pages, 2637 KiB

Open AccessCommunication

Depolymerization of PET with n-Hexylamine, n-Octylamine, and 3-Amino-1-Propanol, Affording Terephthalamides

by Sumiho Hiruba, Yohei Ogiwara and Kotohiro Nomura

Catalysts 2025, 15(2), 129; https://doi.org/10.3390/catal15020129 - 29 Jan 2025

Abstract

The chemical conversion of plastic waste has been considered an important subject in terms of the circular economy, and the chemical recycling and upcycling of poly(ethylene terephthalate) (PET) has been considered one of the most important subjects. In this study, the depolymerization of [...] Read more.

The chemical conversion of plastic waste has been considered an important subject in terms of the circular economy, and the chemical recycling and upcycling of poly(ethylene terephthalate) (PET) has been considered one of the most important subjects. In this study, the depolymerization of PET with n-hexylamine, n-octylamine, and 3-amino-1-propanol has been explored in the presence of Cp*TiCl₃ (Cp* = C₅Me₅). The reactions of PET with n-hexylamine and n-octylamine at 130 °C afforded the corresponding N,N′-di(n-alkyl) terephthalamides in high yields (>90%), and Cp*TiCl₃ plays a role as the catalyst to facilitate the conversion in exclusive selectivity. The reaction of PET with 3-amino-1-propanol proceeded at 100 °C even in the absence of the Ti catalyst, affording N,N′-bis(3-hydroxy) terephthalamides in high yields. A unique contrast has been demonstrated between the depolymerization of PET by transesterification with alcohol and by aminolysis; the depolymerizations with these amines proceeded without the aid of a catalyst. Full article

(This article belongs to the Special Issue State-of-the-Art Polymerization Catalysis)

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13 pages, 1344 KiB

Open AccessArticle

Methanol-Tolerant Pd-Co Alloy Nanoparticles on Reduced Graphene Oxide as Cathode Catalyst for Oxygen Reduction in Fuel Cells

by Chandra Sekhar Yellatur, Venkatachalam Vinothkumar, Poshan Kumar Reddy Kuppam, Juwon Oh and Tae Hyun Kim

Catalysts 2025, 15(2), 128; https://doi.org/10.3390/catal15020128 - 29 Jan 2025

Abstract

The design of efficient and cost-effective electrocatalysts to replace Pt in an oxygen reduction reaction (ORR) is crucial for advancing proton exchange membrane fuel cell (PEMFC) technologies. This study synthesized Pd-Co bimetallic alloy nanoparticles supported on reduced graphene oxide (rGO) through a simple [...] Read more.

The design of efficient and cost-effective electrocatalysts to replace Pt in an oxygen reduction reaction (ORR) is crucial for advancing proton exchange membrane fuel cell (PEMFC) technologies. This study synthesized Pd-Co bimetallic alloy nanoparticles supported on reduced graphene oxide (rGO) through a simple chemical-reduction method, making it suitable for low-cost, large-scale fabrication and significantly reducing the need for Pt. The nanostructures were systematically characterized using various analytical techniques, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), and cyclic voltammetry (CV). Electrochemical investigations revealed that the Pd-Co/rGO catalyst exhibits remarkable ORR performance in an alkaline environment, with an electrode-area-normalized activity rivaling that of the commercial Pt/C catalyst. Remarkably, Pd-Co/rGO demonstrated an onset potential (E_onset) of 0.944 V (vs. RHE) and a half-wave potential (E_1/2) of 0.782 V (vs. RHE), highlighting its excellent ORR activity. Furthermore, the Pd-Co/rGO catalyst displayed superior methanol-tolerant ORR activity, outperforming Pt/C and monometallic Pd/rGO and Co/rGO systems. The enhanced electrocatalytic performance is attributed to the smallest size, consistent shape, and good dispersion of the alloy structure on the RGO surface. These findings establish Pd-Co/rGO as a promising alternative to Pt-based catalysts, addressing key challenges such as methanol crossover while advancing PEMFC technology in alkaline media. Full article

(This article belongs to the Special Issue Insight into Electrocatalysts for Oxygen Reduction Reaction)

19 pages, 666 KiB

Open AccessReview

A Comprehensive Review on Barrelene-Derived α-Diimine Nickel and Palladium Olefin Polymerization Catalysts

by Haotian Zhou, Chunyu Feng, Handou Zheng, Guangshui Tu, Xieyi Xiao and Haiyang Gao

Catalysts 2025, 15(2), 127; https://doi.org/10.3390/catal15020127 - 28 Jan 2025

Abstract

Late transition metal olefin polymerization catalysts have received more attention in the field of catalytic olefin polymerization. Barrelene-based α-diimine nickel and palladium olefin polymerization catalysts are rising stars because of their backbone structure and catalytic properties. In this review, we present a comprehensive [...] Read more.

Late transition metal olefin polymerization catalysts have received more attention in the field of catalytic olefin polymerization. Barrelene-based α-diimine nickel and palladium olefin polymerization catalysts are rising stars because of their backbone structure and catalytic properties. In this review, we present a comprehensive review of barrelene-derived α-diimine nickel and palladium olefin polymerization catalysts. α-Diimine nickel and palladium catalysts are introduced from two aspects: barrelene-derived backbone and aniline derivatives with different substituents. The relationship between catalyst structure and catalytic properties is also emphasized. This review attempts to provide an inspiration for the design of high-performance barrelene-based catalysts. Full article

(This article belongs to the Special Issue State-of-the-Art Polymerization Catalysis)

17 pages, 3856 KiB

Open AccessArticle

Piezoelectric-Driven Fenton System Based on Bismuth Ferrite Nanosheets for Removal of N-acetyl-para-aminophenol in Aqueous Environments

by Chi Zhou, Shenglong Jing, Teng Miao, Nianlai Zhou, Hang Zhang, Yi Zhang, Lin Ge, Wencheng Liu and Zixin Yang

Catalysts 2025, 15(2), 126; https://doi.org/10.3390/catal15020126 - 27 Jan 2025

Abstract

Emerging pollutants, such as N-acetyl-para-aminophenol, pose significant challenges to environmental sustainability, and Bi₂Fe₂O₂ (BFO) nanomaterials are an emerging class of piezoelectric materials. This study presents a novel piezoelectric-driven Fenton system based on Bi₂Fe₄O [...] Read more.

Emerging pollutants, such as N-acetyl-para-aminophenol, pose significant challenges to environmental sustainability, and Bi₂Fe₂O₂ (BFO) nanomaterials are an emerging class of piezoelectric materials. This study presents a novel piezoelectric-driven Fenton system based on Bi₂Fe₄O₉ nanosheets for the efficient degradation of organic pollutants. BFO nanosheets with varying thicknesses were synthesized, and their piezoelectric properties were confirmed through piezoresponse force microscopy and heavy metal ion reduction experiments. The piezoelectric electrons generated within the BFO nanosheets facilitate the in situ production of hydrogen peroxide, which in turn drives the Fenton-like reaction. Furthermore, the piezoelectric electrons enhance the redox cycling of iron in the Fenton process, boosting the overall catalytic efficiency. The energy band structure of BFO nanosheets is well-suited for this process, enabling efficient hydrogen peroxide generation and promoting Fe³⁺ reduction. The findings demonstrate that thinner BFO nanosheets exhibit superior piezoelectric activity, leading to enhanced catalytic performance. Additionally, the incorporation of gold nanodots onto BFO nanosheets further boosts their piezocatalytic efficiency, particularly in the reduction of Cr (VI). The system exhibited robust oxidative capacity, stability, and recyclability, with reactive oxygen species (ROS) verified via electron paramagnetic resonance spectroscopy. Overall, BFO nanosheets, with their optimal energy band structure, self-supplied hydrogen peroxide, and enhanced Fe³⁺ reduction, represent a promising, sustainable solution for advanced oxidation processes in wastewater treatment and other applications. Full article

(This article belongs to the Special Issue Sustainable Catalysis for Green Chemistry and Energy Transition)

17 pages, 1528 KiB

Open AccessArticle

Innovative Production of 3D-Printed Ceramic Monolithic Catalysts for Oxidation of VOCs by Using Fused Filament Fabrication

by Filip Car, Nikolina Zekić, Domagoj Vrsaljko and Vesna Tomašić

Catalysts 2025, 15(2), 125; https://doi.org/10.3390/catal15020125 - 27 Jan 2025

Abstract

In this work, ceramic monolithic catalyst carriers based on zirconium dioxide (ZrO₂) were produced using fused filament fabrication (FFF). The active catalyst components were deposited on the resulting carriers using the wet impregnation method. The activity of the prepared monolithic catalysts [...] Read more.

In this work, ceramic monolithic catalyst carriers based on zirconium dioxide (ZrO₂) were produced using fused filament fabrication (FFF). The active catalyst components were deposited on the resulting carriers using the wet impregnation method. The activity of the prepared monolithic catalysts was evaluated by catalytic oxidation of a mixture of aromatic volatile organic compounds: benzene, toluene, ethylbenzene, and o-xylene (BTEX). The efficiency of the prepared monolithic catalysts was investigated as a function of the geometry of the monolithic carrier (ZDP, Z, and M) and the chemical composition of the catalytically active component (MnFeO_x, MnCuO_x, and MnNiO_x) during the catalytic oxidation of BTEX compounds. The mechanical stability of the catalyst layer and the dimensional stability of the 3D-printed monolithic catalyst carriers were investigated prior to the kinetic measurements. In addition, thorough characterization of the commercial ZrO₂-based filament was carried out. The results of the efficiency of the prepared monolithic catalysts for the catalytic oxidation of BTEX showed that the 3D-printed model M, which contained MnFeO_x as the catalytically active component, was the most successful catalyst for the oxidation of BTEX compounds. The mentioned catalyst enables the catalytic oxidation of all components of the BTEX mixture (>99% efficiency) at a temperature of 177 °C. Full article

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

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36 pages, 7819 KiB

Open AccessReview

Recent Advances in Transition Metal Chalcogenides Electrocatalysts for Oxygen Evolution Reaction in Water Splitting

by Honglin Gao, Ting Yang, Aiyi Dong, Yuliang Xing, Dajun Liu, Yinhua Ma and Kaixin Zhu

Catalysts 2025, 15(2), 124; https://doi.org/10.3390/catal15020124 - 27 Jan 2025

Abstract

Rapid industrial growth has overexploited fossil fuels, making hydrogen energy a crucial research area for its high energy and zero carbon emissions. Water electrolysis is a promising method as it is greenhouse gas-free and energy-efficient. However, OER, a slow multi-electron transfer process, is [...] Read more.

Rapid industrial growth has overexploited fossil fuels, making hydrogen energy a crucial research area for its high energy and zero carbon emissions. Water electrolysis is a promising method as it is greenhouse gas-free and energy-efficient. However, OER, a slow multi-electron transfer process, is the limiting step. Thus, developing efficient, low-cost, abundant electrocatalysts is vital for large-scale water electrolysis. In this paper, the application and progress of transition metal chalcogenides (TMCs) as catalysts for the oxygen evolution reaction in recent years are comprehensively reviewed. The key findings highlight the catalytic mechanism and performance of TMCs synthesized using single or multiple transition metals. Notably, modifications through recombination, heterogeneous interface engineering, vacancy, and atom doping are found to effectively regulate the electronic structure of metal chalcogenides, increasing the number of active centers and reducing the adsorption energy of reaction intermediates and energy barriers in OER. The paper further discusses the shortcomings and challenges of TMCs as OER catalysts, including low electrical conductivity, limited active sites, and insufficient stability under harsh conditions. Finally, potential research directions for developing new TMC catalysts with enhanced efficiency and stability are proposed. Full article

(This article belongs to the Special Issue Recent Advances in Electrocatalysis and Future Perspective)

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20 pages, 6117 KiB

Open AccessArticle

Sustainable Synthesis of Zirconium Dioxide (ZrO₂) Nanoparticles Utilizing Asphodelus fistulosus Extract for Congo Red Degradation

by Rand A. N. Alkhalifa, Abuzar E. A. E. Albadri, Reham Ali, Abdullah H. Alluhayb, Alaa M. Younis and Sayed M. Saleh

Catalysts 2025, 15(2), 123; https://doi.org/10.3390/catal15020123 - 27 Jan 2025

Abstract

This research presents a green approach to synthesizing zirconium oxide (ZrO₂) nanoparticles using an Asphodelus fistulosus plant extract as a reducing and stabilizing agent. The synthesized ZrO₂ nanoparticles were characterized using various advanced techniques. The XRD pattern provides different forms [...] Read more.

This research presents a green approach to synthesizing zirconium oxide (ZrO₂) nanoparticles using an Asphodelus fistulosus plant extract as a reducing and stabilizing agent. The synthesized ZrO₂ nanoparticles were characterized using various advanced techniques. The XRD pattern provides different forms of ZrO₂, like tetragonal and cubic forms, and the results confirmed the successful formation of crystalline ZrO₂ nanoparticles with a definite morphology. The XPS data exhibit that the bioactive chemicals present in the extract, including polyphenols, flavonoids, and reducing sugars, perform the functions of reducing and capping agents. Additionally, CR dye molecules may create hydrogen bonds with these surface moieties, which are approved by FTIR. These interactions may assist in aligning dye molecules with catalytically active regions on ZrO₂ surfaces and may interact with photogenerated species. The catalytic activity of the synthesized ZrO₂ nanoparticles was evaluated for the degradation of Congo red dye under ultraviolet irradiation. The nanoparticles exhibited excellent photocatalytic activity, degrading a significant amount of the dye within a short period. Various parameters were investigated to optimize the photodegradation process, including irradiation time, catalyst dosage, pH, and initial dye concentration. The optimal conditions were determined to be a pH of 7, a catalyst loading of 20 mg/L, and an irradiation time of 75 min, resulting in a remarkable ≈92% degradation efficiency. This green synthesis method offers a sustainable and eco-friendly alternative to conventional chemical methods for producing ZrO₂ nanoparticles, which have potential applications in environmental remediation. Full article

(This article belongs to the Special Issue Nanocatalysts in Energy and Environmental Applications)

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17 pages, 4619 KiB

Open AccessArticle

Alumina Coated with Titanium Dioxide Supported Iron for Hydrogen Production and Carbon Nanotubes via Methane Decomposition

by Hamid Ahmed, Anis H. Fakeeha, Fayez M. Al-Alweet, Syed Farooq Adil, Ahmed E. Abasaeed, Ahmed A. Ibrahim, Ahmed I. Osman, Salwa B. Alreshaidan and Ahmed S. Al-Fatesh

Catalysts 2025, 15(2), 122; https://doi.org/10.3390/catal15020122 - 27 Jan 2025

Abstract

Research on converting methane to hydrogen has gained more attention due to the availability of methane reserves and the global focus on sustainable and environmentally friendly energy sources. The decomposition of methane through catalysis (CDM) has excellent potential to produce clean hydrogen and [...] Read more.

Research on converting methane to hydrogen has gained more attention due to the availability of methane reserves and the global focus on sustainable and environmentally friendly energy sources. The decomposition of methane through catalysis (CDM) has excellent potential to produce clean hydrogen and valuable carbon products. However, developing catalysts that are both active and stable is a highly challenging area of research. Using titanium isopropoxide as a precursor and different loadings of TiO₂ (10 wt.%, 20 wt.%, and 30 wt.%), alumina has been coated with TiO₂ in a single-step hydrothermal synthesis procedure. These synthesized materials are examined as possible support materials for CDM; different wt.% of iron is loaded onto the synthesized support material using a co-precipitation method to enhance the methane conversion via a decomposition reaction. The result shows that the 20 wt.% Fe/20 wt.% Ti-Al (20Fe/20Ti-Al) catalyst demonstrates remarkable stability and exhibits superior performance, reaching a conversion rate of methane of 94% with hydrogen production of 84% after 4 h. The outstanding performance is primarily due to the moderate interaction between the support and the active metal, as well as the presence of the rutile phase. The 20Fe/30Ti-Al catalyst exhibited lower activity than the other catalysts, achieving a methane conversion of 85% and hydrogen production of 79% during the reaction. Raman and XRD analysis revealed that all the catalysts generated graphitic carbon, with the 20Fe/20Ti-Al catalyst specifically producing single-walled carbon nanotubes. Full article

(This article belongs to the Section Industrial Catalysis)

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20 pages, 3425 KiB

Open AccessFeature PaperArticle

Nitrogen/Sulfur Co-Doped Biochar for Peroxymonosulfate Activation in Paracetamol Degradation: Mechanism Insight and Toxicity Evaluation

by Jiaqi Cui, Hong Meng, Yu Chen, Yongqing Zhang, Waseem Hayat and Charles Q. Jia

Catalysts 2025, 15(2), 121; https://doi.org/10.3390/catal15020121 - 26 Jan 2025

Abstract

Advanced oxidation processes based on either peroxydisulfate (PDS) or peroxymonosulfate (PMS), collectively termed persulfate-based advanced oxidation processes (PS-AOPs), show potential in wastewater treatment applications. In this work, the nitrogen (N) and sulfur (S) co-doped biochar (NSBC) was prepared via a one-step pyrolysis of [...] Read more.

Advanced oxidation processes based on either peroxydisulfate (PDS) or peroxymonosulfate (PMS), collectively termed persulfate-based advanced oxidation processes (PS-AOPs), show potential in wastewater treatment applications. In this work, the nitrogen (N) and sulfur (S) co-doped biochar (NSBC) was prepared via a one-step pyrolysis of coffee grounds at 400 to 800 °C as a PMS activator for degrading paracetamol (PCT). The non-metallic NSBC demonstrated exceptional catalytic activity in activating PMS. In the NSBC-800/PMS system, 100% of PCT was completely degraded within 20 min, with a high reaction rate constant (k_obs) of 0.2412 min⁻¹. The system’s versatility was highlighted by its degradation potential across a wide pH range (3–11) and in the presence of various background ions and humic acids. The results of various experiments and characterization techniques showed that the system relied on an NSBC-800-mediated electron transfer as the main mechanism for PCT degradation. Additionally, there was a minor involvement of ¹O₂ in a non-radical degradation pathway. The graphitic N and thiophene-S (C-S-C) moieties introduced by N/S co-doping, as well as the carbonyl (C=O) groups of the biochar, were considered active sites promoting ¹O₂ generation. The total organic carbon (TOC) removal rate reached 37% in 120 min, while the assessment of the toxicity of the degradation products also affirmed the system’s environmental safety. This research provides a novel method for preparing environmentally friendly and cost-effective carbon-based catalysts for environmental remediation. Full article

12 pages, 5537 KiB

Open AccessFeature PaperArticle

Engineering of Cyclodextrin Glucosyltransferase from Paenibacillus macerans for Improved Regioselectivity and Product Specificity Toward Hydroxyflavone Glycosylation

by Jin Wang, Binhao Wang, Jieyu Zhou, Jinjun Dong, Ye Ni and Ruizhi Han

Catalysts 2025, 15(2), 120; https://doi.org/10.3390/catal15020120 - 26 Jan 2025

Abstract

The regioselective glycosylation and product specificity of hydroxyflavonoid compounds profoundly influences their biological activity and stability, offering significant therapeutic potential. However, most cyclodextrin glucosyltransferases (CGTases) inherently lack regioselectivity and product specificity for flavone glycosylation. Herein, a CGTase from Paenibacillus macerans was engineered for [...] Read more.

The regioselective glycosylation and product specificity of hydroxyflavonoid compounds profoundly influences their biological activity and stability, offering significant therapeutic potential. However, most cyclodextrin glucosyltransferases (CGTases) inherently lack regioselectivity and product specificity for flavone glycosylation. Herein, a CGTase from Paenibacillus macerans was engineered for enhanced glycosylation regioselectivity and product specificity by combining molecular docking analysis and saturation mutagenesis strategies. K232L (favoring 4′-and 6-hydroxyflavones) and K232V (favoring 7-hydroxyflavone) were identified with distinct preferences. In addition, H233Y (preferring for 4′-hydroxyflavones), H233T (preferring for 6′-hydroxyflavones), and H233K (preferring for 7′-hydroxyflavones) also demonstrated distinct regioselectivity. These variants further exhibited enhanced hydrolytic activity, enabling the efficient production of short sugar-chain glycosides. Molecular dynamics (MDs) simulations revealed that the variants adopted optimized catalytic conformations with increased loop region flexibility near the binding pocket, enhancing substrate accessibility. These findings underscore the pivotal roles of K232 and H233 in broadening the substrate scope of CGTase and offer valuable guidance for enzyme engineering targeting regioselective glycosylation. Full article

(This article belongs to the Special Issue Advances in Enzyme Engineering, Biocatalysis and Biosynthesis, 2nd Edition)

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14 pages, 15337 KiB

Open AccessArticle

Mesoporous Ce-Ti Catalysts Modified by Phosphotungstic Acid and Chitosan for the Synergistic Catalysis of CVOCs and NOx

by Mingyang Ma, Ruhan Zhang, Yanan Shen, Xin Zhou, Yumeng Zhai, Yumeng Han, Dan Wang, Longjin Zhang, Xinru Song, De Fang and Pijun Gong

Catalysts 2025, 15(2), 119; https://doi.org/10.3390/catal15020119 - 26 Jan 2025

Abstract

Nitrogen oxides (NOx) and chlorinated volatile organic compounds (CVOCs) are major environmental pollutants, posing severe risks to human health and ecosystems. Traditional single-component catalysts often fail to remove both pollutants efficiently, making synergistic catalytic technologies a critical research focus. In this study, a [...] Read more.

Nitrogen oxides (NOx) and chlorinated volatile organic compounds (CVOCs) are major environmental pollutants, posing severe risks to human health and ecosystems. Traditional single-component catalysts often fail to remove both pollutants efficiently, making synergistic catalytic technologies a critical research focus. In this study, a mesoporous HPW-CS-Ce-Ti oxide catalyst, modified with H₃PW₁₂O₄₀ (HPW) and chitosan (CS), was synthesized via self-assembly. The optimized 10HPW-CS-Ce_0.3-Ti catalyst achieved nearly 100% NO conversion at 167–288 °C and a T₉₀ of 291 °C for CVOC conversion, demonstrating superior dual-pollutant removal. HPW and chitosan facilitated mesoporous structure formation, enhancing mass transfer and active site availability. HPW doping also modulated the Ce⁴⁺/Ce³⁺ ratio, boosting redox capacity and surface-active oxygen species, while increasing acidity to promote NH₃ and CVOC adsorption. This study presents a novel catalyst and synthesis method with significant potential for environmental protection and human health. Full article

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

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20 pages, 6075 KiB

Open AccessFeature PaperArticle

Photocatalysis by Mixed Oxides Containing Niobium, Vanadium, Silica, or Tin

by Agnieszka Feliczak-Guzik, Agata Wawrzyńczak and Izabela Nowak

Catalysts 2025, 15(2), 118; https://doi.org/10.3390/catal15020118 - 26 Jan 2025

Abstract

Nb-Sn, V-Sn mixed-metal oxides and Nb-Si, V-Si metal oxide–silicas were successfully synthesized through a “soft” templating method, in which appropriate amounts of metal salts (either niobium(V) chloride, or vanadium(IV) oxide sulfate hydrate or tin(II) chloride dihydrate) or tetraethyl orthosilicate (TEOS) were mixed with [...] Read more.

Nb-Sn, V-Sn mixed-metal oxides and Nb-Si, V-Si metal oxide–silicas were successfully synthesized through a “soft” templating method, in which appropriate amounts of metal salts (either niobium(V) chloride, or vanadium(IV) oxide sulfate hydrate or tin(II) chloride dihydrate) or tetraethyl orthosilicate (TEOS) were mixed with hexadecyltrimethylammonium chloride (HDTA) or sodium dodecyl sulfate (SDS) solutions to obtain a new series of mesoporous oxides, followed by calcination at different temperatures. As-obtained samples were characterized by SEM, TEM, XRD, and UV-Vis spectra techniques. The photocatalytic activities of the samples were evaluated by degradation of methyl orange II (MO) under simulated sunlight irradiation. The effects of metal species and calcination temperature on the physicochemical characteristic and photocatalytic activity of the samples were investigated in detail. The results indicated that, compared to pure oxides, mixed-metal oxide showed superior photocatalytic performance for the degradation of MO. A maximum photocatalytic discoloration rate of 97.3% (with MO initial concentration of 0.6·10⁻⁴ mol/dm³) was achieved in 300 min with the NbSiOx material, which was much higher than that of Degussa P25 under the same conditions. Additionally, the samples were tested in the photochemical oxidation process, i.e., advanced oxidation processes (AOPs) to treat the commercial non-ionic surfactant: propylene oxide ethylene oxide polymer mono(nonylphenyl) ether (N8P7, PCC Rokita). A maximum of 99.9% photochemical degradation was achieved in 30 min with the NbSiOx material. Full article

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17 pages, 1852 KiB

Open AccessArticle

Bi₄Ti₃O₁₂-V/Ag Composite with Oxygen Vacancies and Schottky Barrier with Photothermal Effect for Boosting Nizatidine Degradation

by Sheng Liu, Chen Hu, Ying Gong, Yujuan Guo, Zhenping Cheng, Mengyi Yuan, Zixiang Liao, Xuewen Xiao, Zushun Xu, Jun Du, Ping Shen and Qing Li

Catalysts 2025, 15(2), 117; https://doi.org/10.3390/catal15020117 - 24 Jan 2025

Abstract

Piezo-photocatalysis is a promising solution to address both water pollution and the energy crisis. However, the recombination of electron–hole pairs often leads to poor performance, rendering current piezoelectric photocatalysts unsuitable for industrial water treatment. To overcome this issue, oxygen vacancies (V) and Ag [...] Read more.

Piezo-photocatalysis is a promising solution to address both water pollution and the energy crisis. However, the recombination of electron–hole pairs often leads to poor performance, rendering current piezoelectric photocatalysts unsuitable for industrial water treatment. To overcome this issue, oxygen vacancies (V) and Ag nanoparticles (NPs) are introduced into Bi₄Ti₃O₁₂ (BTO) nanosheets, forming Schottky junctions (BTO-V/Ag). These 2D/3D structures offer more exposed active sites, shorter carrier separation distances, and improved piezo-photocatalytic performance. Additionally, the photothermal effect of Ag NPs supplies additional energy to counteract adsorption changes caused by active species, promoting the generation of more active species. The rate constant of the optimized BTO-V/Ag-2 in the piezo-photocatalytic degradation of nizatidine (NZTD) was 4.62 × 10⁻² min⁻¹ (with a removal rate of 98.34%), which was 4.32 times that of the initial BTO. Moreover, the composite catalyst also showed good temperature and pH response. This study offers new insights into the regulatory mechanisms of piezo-photocatalysis at the Schottky junction. Full article

(This article belongs to the Topic Wastewater Treatment by Physical, Chemical, Photochemical, and Biological Processes, and Their Combinations)

17 pages, 3587 KiB

Open AccessArticle

Detection of Dopamine Using Hybrid Materials Based on NiO/ZnO for Electrochemical Sensor Applications

by Irum Naz, Aneela Tahira, Arfana Begum Mallah, Elmuez Dawi, Lama Saleem, Rafat M. Ibrahim and Zafar Hussain Ibupoto

Catalysts 2025, 15(2), 116; https://doi.org/10.3390/catal15020116 - 24 Jan 2025

Abstract

Dopamine is a neurotransmitter which is classified as a catecholamine. It is also one of the main metabolites produced by some tumor types (such as paragangliomas and neoblastomas). As such, determining and monitoring the level of dopamine is of the utmost importance, ideally [...] Read more.

Dopamine is a neurotransmitter which is classified as a catecholamine. It is also one of the main metabolites produced by some tumor types (such as paragangliomas and neoblastomas). As such, determining and monitoring the level of dopamine is of the utmost importance, ideally using analytical techniques that are sensitive, simple, and low in cost. Due to this, we have developed a non-enzymatic dopamine sensor that is highly sensitive, selective, and rapidly detects the presence of dopamine in the body. A hybrid material fabricated with NiO and ZnO, based on date fruit extract, was synthesized by hydrothermal methods and using NiO as a precursor material. This paper discusses the role of date fruit extracts in improving NiO’s catalytic performance with reference to ZnO and the role that they play in this process. An X-ray powder diffraction study, a scanning electron microscope study, and a Fourier transform infrared spectroscopy study were performed in order to investigate the structure of the samples. It was found that, in the composite NiO/ZnO, NiO exhibited a cubic phase and ZnO exhibited a hexagonal phase, both of which exhibited well-oriented aggregated cluster shapes in the composite. A hybrid material containing NiO and ZnO has been found to be highly electro-catalytically active in the advanced oxidation of dopamine in a phosphate buffer solution at a pH of 7.3. It has been found that this can be accomplished without the use of enzymes, and the range of oxidation used here was between 0.01 mM and 4 mM. The detection limit of non-enzymatic sensors is estimated to be 0.036 μM. Several properties of the non-enzymatic sensor presented here have been demonstrated, including its repeatability, selectivity, and reproducibility. A test was conducted on Sample 2 for the detection of banana peel and wheat grass, and the results were highly encouraging and indicated that biomass waste may be useful for the manufacture of medicines to treat chronic diseases. It is thought that date fruit extracts would prove to be valuable resources for the development of next-generation electrode materials for use in clinical settings, for energy conversion, and for energy storage. Full article

(This article belongs to the Section Electrocatalysis)

19 pages, 1223 KiB

Open AccessReview

Bibliometric Analysis on Graphitic Carbon Nitride (g-C₃N₄) as Photocatalyst for the Remediation of Water Polluted with Contaminants of Emerging Concern

by José M. Veiga-del-Baño, Gabriel Pérez-Lucas, Pedro Andreo-Martínez and Simón Navarro

Catalysts 2025, 15(2), 115; https://doi.org/10.3390/catal15020115 - 24 Jan 2025

Abstract

Carbon nitrides are polymeric materials with a broad range of applications, including photocatalysis. Among them, graphitic carbon nitride (g-C₃N₄), a low-cost material, is an excellent photocatalyst under visible light irradiation owing to its features such as correct band positions, [...] Read more.

Carbon nitrides are polymeric materials with a broad range of applications, including photocatalysis. Among them, graphitic carbon nitride (g-C₃N₄), a low-cost material, is an excellent photocatalyst under visible light irradiation owing to its features such as correct band positions, high stability and non-toxicity. g-C₃N₄ is a metal-free material that is easily synthesized by polymerizing nitrogen-rich compounds and is an efficient heterogeneous catalyst for many reaction procedures due to its distinctive electronic structure and the benefits of the mesoporous texture. In addition, in situ or post-modification of g-C₃N₄ can further improve catalytic performance or expand its application for remediating environmental pollution. Water pollution from organic compounds such as pesticides and pharmaceuticals is increasing dramatically and is becoming a serious problem around the world. These pollutants enter water supplies in a variety of ways, including industrial and hospital wastewater, agricultural runoff, and chemical use. To solve this problem, photocatalysis is a promising technology. Without the use of other oxidative chemicals, g-C₃N₄ uses renewable solar energy to transform harmful pollutants into harmless products. As a result, much recent research has focused on the photocatalytic activity of g-C₃N₄ for wastewater treatment. For this reason, the main objective of this paper is to contribute a chronological overview of the bibliometrics on g-C₃N₄ for the removal of pesticides and pharmaceuticals from water using the tools BibExcel, Bibliometrix and R-Studio IDE. A bibliometric analysis was performed using the Science Citation Index Expanded (WoS^©) database to analyze the scientific literature published in the field over the last 10 years. The results were used to identify limitations and guide future research. Full article

(This article belongs to the Special Issue Recent Advances in Photocatalytic Degradation of Pharmaceuticals and Pesticides)

17 pages, 6357 KiB

Open AccessArticle

Molecular Modelling of Novel Selective Inhibitors of Mycobacterium tuberculosis CYP125A1 Protein Based on Natural Product-like Structures

by Sandra G. Zárate and Agatha Bastida

Catalysts 2025, 15(2), 114; https://doi.org/10.3390/catal15020114 - 24 Jan 2025

Abstract

Background: Tuberculosis (TB) is the second leading cause of death from infectious diseases, with 10.6 million cases and 1.3 million deaths. Conventional treatment faces difficulties due to the emergence of resistant strains, such as MDR and XDR-TB. M. tuberculosis uses host cholesterol as [...] Read more.

Background: Tuberculosis (TB) is the second leading cause of death from infectious diseases, with 10.6 million cases and 1.3 million deaths. Conventional treatment faces difficulties due to the emergence of resistant strains, such as MDR and XDR-TB. M. tuberculosis uses host cholesterol as an energy source, via the CYP125A1 protein, which catalyses cholesterol oxidation, a process critical for the survival of the bacterium. Methods: This study used computational methods to identify selective inhibitors of the CYP125A1 enzyme. A total of 5968 structure-like compounds from the ASINEX database were evaluated for protein-binding affinity. In addition, docking tests were performed to verify whether the identified compounds could interact with other M. tuberculosis proteins, such as InhA and the human CYP3A4 protein to assess possible off-target effects. Results: The top ten compounds showed a good pharmacological profile and favourable binding energies. Compounds LAS 52160899 and LAS 7298627 served as a basis to search for others with known biological activity, with DB07463 and DB01081 selected as candidates. Conclusions: Potential new inhibitors of the CYP125A1 enzyme were identified. These findings highlight the importance of further research to develop new treatments against M. tuberculosis, especially to combat resistant strains. Full article

(This article belongs to the Section Biocatalysis)

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18 pages, 7280 KiB

Open AccessArticle

Photocatalytic Degradation of Tetracycline Hydrochloride Using TiO₂/CdS on Nickel Foam Under Visible Light and RSM–BBD Optimization

by Kefu Zhu, Lizhe Ma, Jieli Duan, Zhiyong Fang and Zhou Yang

Catalysts 2025, 15(2), 113; https://doi.org/10.3390/catal15020113 - 24 Jan 2025

Abstract

This study investigates the photocatalytic degradation of tetracycline hydrochloride (TCH) using a TiO₂/CdS composite nanocatalyst synthesized on flexible nickel foam via a dipping–pull method. By comparing the photocatalytic degradation of TCH by TiO₂/CdS with different precursor ratios, it was [...] Read more.

This study investigates the photocatalytic degradation of tetracycline hydrochloride (TCH) using a TiO₂/CdS composite nanocatalyst synthesized on flexible nickel foam via a dipping–pull method. By comparing the photocatalytic degradation of TCH by TiO₂/CdS with different precursor ratios, it was found that TiO₂/CdS-1.43% exhibited better photocatalytic degradation performance. The X-ray diffraction (XRD) pattern of the TiO₂/CdS composite retains the characteristic peaks of both TiO₂ and CdS, indicating the successful formation of the composite. According to the analysis of ultraviolet–visible spectroscopy (UV–Vis), the absorption edge of TiO₂/CdS is approximately 530 nm. The transmission electron microscopy (TEM) images show Cd and S evenly, densely distributed in TiO₂/CdS, further validating its successful synthesis. X-ray photoelectron spectroscopy (XPS) analysis reveals that Cd and Ti elements exist in the forms of Cd²⁺ and Ti⁴⁺, respectively. TiO₂/CdS loading uniformity on the nickel foam was assessed using super-depth microscopy. The removal efficiency of 10 L of 20 mg/L TCH solution achieved 53.89%, respectively, under response surface methodology—Box–Behnken design (RSM–BBD) optimal conditions (28 g catalyst, 325 rpm, pH = 9.04 within 150 min). Furthermore, five successive cycling experiments demonstrated strong stability, with a catalyst loss of only 4.44%. Finally, free radical scavenging experiments revealed that ·O₂⁻ radicals are the primary active species. This study highlights the potential of TiO₂/CdS composites supported on nickel foam for efficient photocatalytic degradation of antibiotic pollutants in water. Full article

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

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17 pages, 9669 KiB

Open AccessReview

Photocatalytic Degradation of Mycotoxins by Heterogeneous Photocatalysts

by Yawei Huang, Muyue Li and Jing Liu

Catalysts 2025, 15(2), 112; https://doi.org/10.3390/catal15020112 - 23 Jan 2025

Abstract

Mycotoxins are highly toxic secondary metabolites that can pose a serious threat to food safety, human health, and the environment. As a promising detoxification method, photocatalysis has shown great potential for mycotoxin degradation due to its high efficiency, low cost, and green advantages. [...] Read more.

Mycotoxins are highly toxic secondary metabolites that can pose a serious threat to food safety, human health, and the environment. As a promising detoxification method, photocatalysis has shown great potential for mycotoxin degradation due to its high efficiency, low cost, and green advantages. Heterogeneous photocatalysis using a semiconductor as a mediator is now regarded as an effective approach for mycotoxin degradation. The aim of this study was to review the recent developments, mainly in the photocatalytic degradation of mycotoxin (e.g., AFB1, FB1, DON, and ZEN). The principle, feasibility, and main semiconducting catalysts of mycotoxin photodegradation are introduced and discussed, including metal oxides (transition, noble, and rare earth metals), carbons (graphene, carbon nitride, and biochar) and other composites (MOFs and LDHs). This review will contribute to the development of semiconductor photocatalysts and photocatalytic degradation for mycotoxins decontamination. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry, 2nd Edition)

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