Search Results (978)

Dry reforming of methane and ethanol is a promising catalytic process for the conversion of carbon dioxide and hydrocarbon feedstocks into synthesis gas (H₂/CO), which serves as a key platform for the production of fuels and chemicals. Over the past decade, substantial progress has been achieved in the design of catalysts with enhanced activity and stability under the demanding conditions of these strongly endothermic reactions. This review summarizes the latest developments in catalyst systems for DRM and EDR, including Ni-based catalysts, perovskite-type oxides, MOF-derived materials, and high-entropy alloys. Particular attention is given to strategies for suppressing carbon deposition and preventing metal sintering, such as oxygen vacancy engineering in oxide supports, rare earth and transition metal doping, strong metal–support interactions, and morphological control via core–shell and mesoporous architectures. These approaches have been shown to improve coke resistance, maintain metal dispersion, and extend catalyst lifetimes. The review also highlights emerging concepts such as multifunctional hybrid systems and innovative synthesis methods. By consolidating recent findings, this work provides a comprehensive overview of current progress and future perspectives in catalyst development for DRM and EDR, offering valuable guidelines for the rational design of advanced catalytic materials. Full article

Achieving selective, direct conversion of methane into value-added chemicals requires catalysts that can navigate the intrinsic trade-off between C–H bond activation and over-dehydrogenation. Transition metal phosphides (TMPs) have emerged as promising catalysts that can tune this selectivity. This work utilizes density functional theory (DFT) to systematically assess how the transition metal’s identity (M = Fe, Co, Ni) in isostructural M₂P phosphides governs this balance. The findings reveal that the high reactivity of Fe₂P and Co₂P, which facilitates initial methane activation, also promotes facile deep dehydrogenation pathways to coke precursors like CH*. In stark contrast, Ni₂P exhibits a moderated reactivity that kinetically hinders CH* formation while simultaneously exhibiting the lowest activation barrier for the C–C coupling of CH₂* intermediates to form ethylene. This revealed trade-off between the high reactivity of Fe/Co phosphides and the high selectivity of Ni₂P offers a guiding principle for the rational design of advanced bimetallic phosphides for efficient methane upgrading. Full article

Water electrolysis represents a viable and scalable green hydrogen production technology, which mitigates carbon emissions and contributes to environmental sustainability. Transition metal-based layered double hydroxides (LDHs) exhibit excellent oxygen evolution reaction (OER) efficiency, attributed to their adjustable interlayer spacing combined with abundant active sites. Here, we report a uniform multimetallic catalyst, demonstrating robust and efficient OER performance for high-performance water splitting. SEM and TEM confirmed its ultrathin hierarchical nanosheet structure. The characteristic peaks of LDH in XRD and Raman spectra further verified the successful synthesis of the LDH material. Fe-CoZn LDH delivers exceptional OER performance in 1 M KOH, requiring overpotentials of just 209, 238, and 267 mV to reach 10, 100, and 400 mA cm⁻², respectively. The catalyst also demonstrates exceptional hydrogen evolution reaction (HER) performance, achieving 10 mA cm⁻² at 119 mV. It also has excellent stability, with stable operation for up to 100 h under 100 mA cm⁻² in 1 M KOH electrolyte solution. Full article

Although transition metal catalysts have been used extensively for the polymerization of hydrocarbon monomers, several cationic aluminum catalysts have been also known to promote polymerization of ethylene and 1,3-butadiene. Transition-metal catalyzed polymerization generally proceeds via coordination and insertion of the monomer on one metal center. In contrast, in ethylene polymerization using aluminum catalysts, a bimolecular chain growth mechanism, including the reaction between neutral aluminum species and the monomer activated by cationic aluminum species, is proposed. Although previously reported aluminum catalysts are based on a monoaluminum complex, a dialuminum complex is expected to catalyze the polymerization more efficiently, considering the proposed mechanism. In this work, we found that a combination of diphosphines and MAO promotes polymerization of ethylene and 1,3-butadiene. The 1,4-bis(diphenylphosphino)butane (DPPB)/methylaluminoxane (MAO) system showed a much higher activity toward ethylene polymerization than other monophosphine or diphosphine/MAO systems. NMR analysis of a mixture of diphosphine and MAO indicates the formation of cationic dialuminum species in the presence of DPPB, whereas the formation of cationic monoaluminum species occurs in the presence of other diphosphines. The 2,2′-bis(diphenylphosphino)-1,1′-biphenyl (BIPHEP)/MAO system promoted 1,3-butadiene polymerization to give polybutadiene having a cis-1,4 selectivity of up to 93.8%. Full article

In recent years, one of the major problems facing humanity has been the contamination of the environment by various organic pollutants, with some of them exhibiting environmental persistence or pseudo-persistence. For this reason, it is necessary today, more than ever, to find new and effective methods for degrading these persistent pollutants. Transition metal selenides (TMSes) have emerged as a versatile and promising class of catalysts for the degradation of organic pollutants through various advanced oxidation processes (AOPs). The widespread use of these materials lies in the desirable characteristics they offer, such as unique electronic structures, narrow band gaps, high electrical conductivity, and multi-valent redox behavior. This review comprehensively examines recent progress in the design, synthesis, and application of these TMSes—including both single- and composite systems, such as TMSes/g-C₃N₄, TMSes/TiO₂, and heterojunctions. The catalytic performance of these systems is being highlighted, regarding the degradation of organic pollutants such as dyes, pharmaceuticals, antibiotics, personal care products, etc. Further analysis of the mechanistic insights, structure–activity relationships, and operational parameter effects are critically discussed. Emerging trends, such as hybrid AOPs combining photocatalysis with PMS or electro-activation, and the challenges of stability, scalability, and real wastewater applicability are explored in depth. Finally, future directions emphasize the integration of multifunctional activation methods for the degradation of organic pollutants. This review aims to provide a comprehensive analysis and pave the way for the utilization of TMSe catalysts in sustainable and efficient wastewater remediation technologies. Full article

The escalating problem of nitrate pollution, coupled with the environmental burden of the Haber-Bosch process, has spurred intense interest in the electrocatalytic nitrate reduction reaction (eNO₃RR) as a sustainable route for simultaneous wastewater treatment and ammonia production. However, the efficiency and selectivity of eNO₃RR are hampered by the multi-step proton-coupled electron transfer process and the competing hydrogen evolution reaction. This review provides a comprehensive and critical overview of recent advances in understanding and designing catalysts for eNO₃RR. We begin by elucidating the fundamental mechanisms and key reaction pathways, followed by a discussion on how critical parameters (e.g., electrolyte microenvironment, applied potential, reactor design) dictate performance. Further discussion of recent advances in catalysts, including single-metal catalysts, alloy catalysts, transition metal compounds, single-atom catalysts, carbon-based non-metal catalysts, and composite catalysts, highlights their significant roles in enhancing both the efficiency and selectivity. A distinctive feature of this review is its consistent critical assessment of catalysts through the dual lenses of practicality and sustainable development. Finally, we outline prevailing challenges and propose future research directions aimed at developing scalable and commercially viable electrocatalytic systems for green nitrogen management. Full article

Despite intense interest in the catalytic potential of transition metal oxide heterostructures, originating from their large surface area and tunable chemistry, the fabrication of well-defined multicomponent oxide coatings with controlled architectures remains challenging. Here, we demonstrate a simple and effective swelling-assisted sequential infiltration synthesis (SIS) strategy to fabricate hierarchically porous multicomponent metal-oxide electrocatalysts with tunable bimetallic composition. A combination of solution-based infiltration (SBI) of transition metals, iron (Fe), nickel (Ni), and cobalt (Co), into a block copolymer (PS73-b-P4VP28) template, followed by vapor-phase infiltration of alumina using sequential infiltration synthesis (SIS), was employed to synthesize porous, robust, conformal and transparent multicomponent metal-oxide coatings like Fe/AlO_x, Fe+Ni/AlO_x, and Fe+Co/AlO_x. Electrochemical assessments for the oxygen evolution reaction (OER) in a 0.1 M KOH electrolyte demonstrated that the Fe+Ni/AlO_x composite exhibited markedly superior catalytic activity, achieving an impressive onset potential of 1.41 V and a peak current density of 3.29 mA/cm². This superior activity reflects the well-known synergistic effect of alloying transition metals with a trace of Fe, which facilitates OER kinetics. Overall, our approach offers a versatile and scalable path towards the design of stable and efficient catalysts with tunable nanostructures, opening new possibilities for a wide range of electrochemical energy applications. Full article

The activation of carbon dioxide by transition metal complexes is a fundamental process in catalysis and carbon capture. In this study, density functional theory (DFT) calculations, combined with Quantum Theory of Atoms in Molecules (QTAIM) and Natural Orbitals for Chemical Valency (NOCV) analyses, were employed to investigate the bonding characteristics and electronic structure of Fe(0)–, Pd(0)–, and Pt(0)–phosphine complexes with CO₂. The Fe(0) complexes exhibited the strongest CO₂ activation, characterized by substantial C=O bond elongation, significant charge transfer, and strong $\pi$-backdonation. In contrast, Pd(0) complexes showed minimal CO₂ activation, while Pt(0) complexes displayed intermediate behavior. The electronic effects of phosphine ligands were also analyzed, revealing that electron-donating phosphines enhance CO₂ activation, whereas electron-withdrawing phosphines weaken metal–CO₂ interactions. These findings provide key insights into the design of transition-metal-based catalysts for CO₂ conversion and utilization. Full article

This review covers the current state, challenges, and future directions of catalytic combustion technologies for mitigating fugitive methane emissions from the fossil fuel industry. Methane, a potent greenhouse gas, is released from diverse sources, including natural gas production, oil operations, coal mining, and natural gas engines. The paper details the primary emission sources, and addresses the technical difficulties associated with dilute and variable methane streams such as ventilation air methane (VAM) from underground coal mines and low-concentration leaks from oil and gas infrastructure. Catalytic combustion is a useful abatement solution due to its ability to destruct methane in lean and challenging conditions at lower temperatures than conventional combustion, thereby minimizing secondary pollutant formation such as NO_X. The review surveys the key catalyst classes, including precious metals, transition metal oxides, hexa-aluminates, and perovskites, and underscores the crucial role of reactor internals, comparing packed beds, monoliths, and open-cell foams in terms of activity, mass transfer, and pressure drop. The paper discusses advanced reactor designs, including flow-reversal and other recuperative systems, modelling approaches, and the promise of advanced manufacturing for next-generation catalytic devices. The review highlights the research needs for catalyst durability, reactor integration, and real-world deployment to enable reliable methane abatement. Full article

Electrocatalytic CO₂ reduction driven by renewable electricity offers a sustainable approach to producing valuable chemicals, though it is often hindered by low activity and selectivity. CuO, an important transition metal oxide, exhibits unique advantages in photoelectrocatalysis due to its high intrinsic catalytic activity and ability to serve as an active site for CO₂ reduction. SiO₂, a widely used substrate, facilitates Cu loading and increases the specific surface area of the catalyst. Meanwhile, g-C₃N₄ provides excellent visible-light responsiveness and efficient charge carrier mobility. Together, CuO, SiO₂, and g-C₃N₄ are earth-abundant, low-cost, and chemically stable, making them ideal for solar-to-fuel applications. Here, a novel ternary heterojunction photocatalyst was constructed using SiO₂, CuO, and g-C₃N₄. The heterostructure significantly improves light-harvesting efficiency, promotes efficient charge separation and transport, and simultaneously mitigates photogenerated carrier recombination and catalyst corrosion. The resulting SiO₂@CuO/g-C₃N₄ catalyst demonstrates outstanding CO₂ conversion performance, achieving a CO yield of 17 mmolg⁻¹h⁻¹ at 1.2 V_RHE with nearly 100% selectivity. Moreover, this work systematically investigates the electrocatalytic CO₂ reduction reaction (CO₂RR) mechanism on Cu-based catalysts, offering insights into the formation of high-value multicarbon products and highlighting the potential of rational heterojunction design in enhancing solar-driven fuel production efficiency. Full article

Waste lithium-ion batteries (LIBs), which usually contain dangerous organic electrolytes and transition metals, including nickel, cobalt, iron, and manganese, can hurt the environment and human health. Substantial advancements have been achieved in employing high-efficiency, economical, and environmentally sustainable techniques for the recycling of spent LIBs. Converting exhausted LIBs into efficient energy conversion catalysts straightforwardly is a good strategy for addressing metal resource constraints and clean energy concerns. This transforms waste cathodes, anodes, binders, and separators from depleted LIBs into electrocatalysts free of platinum group metals for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). The composite, including transition metal oxide, graphene oxide, and carbon mass, will be synthesized from spent LIBs, demonstrating enhanced electrocatalytic activity. Utilizing “waste-to-energy” methods for used LIBs as catalysts would provide substantial benefits in environmental preservation and the effective production of functional materials in metal–air batteries. Full article

Transition metal dichalcogenides (TMSs), exemplified by molybdenum disulfide (MoS₂), exhibit significant potential as alternatives to noble metals (e.g., Pt) for the hydrogen evolution reaction (HER). However, conventional synthesis methods of MoS_x often suffer from active site loss, harsh reaction conditions, or undesirable oxidation, limiting their practical applicability. The development of MoS_x with high-density active sites remains a formidable challenge. Herein, we propose a novel strategy employing [Mo₃S₁₃]²⁻ clusters as precursors to construct three-dimensional amorphous MoS_x nanosheets through optimized hydrothermal and solvent evaporation-induced self-assembly approaches. Comprehensive characterization confirms the material’s unique amorphous lamellar structure, featuring preserved [Mo₃S₁₃]²⁻ units and engineered interlayer dislocations that facilitate enhanced electron transfer and active site exposure. This work not only establishes [Mo₃S₁₃]²⁻ clusters as effective building blocks for high-performance MoS_x catalysts, but also provides a scalable and environmentally benign synthesis route for the large-scale production of such nanostructured a-MoS_x. Our findings facilitate the rational design of non-noble HER catalysts via structural engineering, with broad implications for energy conversion technologies. Full article

The increasing occurrence of antibiotics in water bodies all over the world has raised concerns because of the prospect that they might have genotoxic and antibiotic-resistant consequences in both people and aquatic creatures. In particular, it has been discovered that the construction of hybrid photocatalytic composite materials has greater antibiotic degradation efficiencies. The hybrid photocatalysts deliver improved photoabsorbance, charge separation, transfer, and redox characteristics, as well as enhanced photostability and rapid recovery, due to their optimal characteristic qualities, including superior structural, surface, and interfacial properties. Additionally, metal-based electrocatalysts have garnered notable attention in the field of water splitting as they are low-cost, standard and have the potential to be used in green and clean technology. MXene, a family of two-dimensional transition metal carbides and nitrides, was discovered in 2011 due to its high conductivity, large surface area, and abundance of catalytically active sites. By making hybrid structures of MXene with other materials, which have shown better electrocatalytic activity than pure MXenes. The two half-cell processes involved in water electrolysis are the oxygen generation at the anode site and the hydrogen production at the cathode site. This review paper provides a summary of the latest advancements in the design of several hybrid systems, catalysts and their effectiveness in degrading a range of newly discovered antibiotic pharmaceutical pollutants in aquatic settings, as well as recent developments on the use of MXenes and MXene-based hybrid structures such as OER, HER, and bifunctional electrocatalysts for general water splitting. Full article

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) offer distinct advantages over their low-temperature counterparts. However, their commercial viability is significantly hampered by durability challenges stemming from electrocatalyst support degradation in the corrosive phosphoric acid environment. This review provides a comprehensive analysis of advanced strategies to overcome this critical durability issue. Two main research directions are explored. The first involves engineering more robust carbon-based materials, including graphitized carbons, carbon nanostructures (nanotubes and graphene), and heteroatom-doped carbons, which enhance stability by modifying the carbon’s intrinsic structure and surface chemistry. The second direction focuses on replacing carbon entirely with intrinsically stable non-carbonaceous materials. These include metal oxides (e.g., TiO₂, SnO₂), transition metal carbides (e.g., WC, TiC), and nitrides (e.g., Nb₄N₅). For these non-carbon materials, a key focus is on overcoming their typically low electronic conductivity through strategies such as doping and the formation of multi-component composites. The analysis benchmarks the performance and durability of these advanced supports, concluding that rationally designed composite materials, which combine the strengths of different material classes, represent the most promising path toward developing next-generation, long-lasting catalysts for HT-PEMFCs. Full article

Brønsted acid-catalyzed, regiodivergent hydroindolation of indoles with terminal aryl alkynes was developed, affording bis(indolyl)alkanes in good to excellent yields. Systematic investigations revealed that temperature variation plays a key role in determining the regioselectivity of anti-Markovnikov and Markovnikov addition reactions. The reaction proceeds efficiently under transition metal-free conditions in an environmentally benign water/alcohol solvent system, using readily available and inexpensive p-toluenesulfonic acid (TsOH) as the catalyst. Control experiments and mechanistic studies support distinct reaction pathways for each regioisomer. Full article