Search Results (984)

Electrochemical chlorine production is of considerable industrial importance in areas such as water treatment, chemical manufacturing, and disinfection. However, conventional precious metal-based dimensionally stable anodes (DSAs), such as RuO₂- and IrO₂-based systems, are limited by high cost and resource constraints, motivating the development of low-cost alternative catalysts. In this study, Mn₃O₄ electrodes with controllable defect characteristics were fabricated by electrochemical deposition under various processing conditions. The effects of defect modulation and surface modification on the structural, electronic, and electrochemical properties of the electrodes were systematically evaluated. X-ray diffraction analysis confirmed that all deposited films retained a stable tetragonal Mn₃O₄ crystal structure, indicating that the deposition parameters primarily influenced defect states rather than the bulk phase. Mott–Schottky measurements revealed that the Mn₃O₄ electrodes exhibited p-type semiconducting behavior, with charge carrier densities on the order of 10¹⁴ cm⁻³, suggesting that oxygen vacancy-related defect states may contribute to the observed electronic properties of the electrodes. To further enhance anodic performance, Pt was introduced onto the Mn₃O₄ surface via sputtering, resulting in significantly improved charge transfer characteristics. Electrochemical measurements demonstrated that the best performing Pt/Mn₃O₄ electrodes delivered a current density exceeding 100 mA cm⁻² at an applied potential of 1.5 V versus Ag/AgCl. More importantly, defect-enriched Pt/Mn₃O₄ electrodes exhibited markedly enhanced chlorine evolution activity, with the chlorine production rate increasing from approximately 14 µmol cm⁻² to 29 µmol cm⁻², corresponding to an enhancement of about 2.07-fold. Faradaic efficiency analysis further showed that sample (g) and sample (n) achieved chlorine evolution efficiencies of 59.2% and 74.6%, respectively, indicating a higher tendency toward chlorine evolution for the Pt-modified electrodes under the tested conditions. These findings suggest that the synergistic combination of defect engineering and surface modification effectively modulates the electronic structure of Mn₃O₄, providing a viable strategy for improving chlorine evolution performance. Full article

Carbon-based bifunctional oxygen electrocatalysts with rationally designed architectures are essential for high-performance rechargeable zinc–air batteries (ZABs), yet the concurrent optimization of catalytic activity, durability, and mass transport remains challenging. Herein, hierarchical ZnCo carbon nanofibers/carbon nanotubes (CNFs@CNTs) are fabricated via single-nozzle electrospinning followed by melamine-assisted pyrolysis under a ZnCl₂-regulated atmosphere. During thermal treatment, Co species embedded within carbon nanofibers catalyze in situ carbon nanotube growth, while ZnCl₂ vapor modulates the carbonization process and surface chemistry, collectively generating a hierarchical CNFs@CNTs architecture with high surface area and abundant exposed active sites. As a result, ZnCo CNFs@CNTs exhibit outstanding bifunctional ORR/OER activity, surpassing Zn-free and Co-free counterparts. Combined structural and electrochemical analyses reveal that the synergistic interaction between Co active centers and Zn-assisted carbon structural regulation enhances reaction kinetics and long-term stability. When implemented as air electrodes in rechargeable ZABs, ZnCo CNFs@CNTs deliver high power density, reduced charge–discharge polarization, and excellent cycling durability, demonstrating strong practical applicability. This work presents an effective strategy for constructing hierarchical CNFs@CNTs composites via electrospinning and dual-component thermal regulation, offering new insights into the design of high-efficiency bifunctional air electrodes for advanced ZABs. Full article

Despite the long-standing recognition of nickel as an effective electrocatalyst for the alkaline hydrogen evolution reaction (HER), the majority of extant studies primarily focus on initial catalytic performance or short-term stability under relatively low current densities. In practical alkaline water electrolysis, however, electrodes operate continuously at elevated current densities for extended periods, where surface chemical states and electrochemical responses may evolve dynamically. A systematic understanding of such time-dependent behaviour remains limited, particularly for electrodeposited nickel under sustained operation. In this study, the long-term HER performance of electrodeposited Ni electrodes at a current density of 100 mA cm⁻² over 120 h is investigated. The objective of this study is to correlate the evolution of electrochemical performance with changes in surface chemical states during prolonged electrolysis. To this end, a combination of methods was employed, including polarization measurements, electrochemical impedance analysis, double-layer capacitance evaluation, and ex situ surface characterization. In contrast to the tendency to prioritize absolute enhancement of activity, this study places greater emphasis on the transient decline–recovery–stabilization behaviour that is observed during operation. Furthermore, it discusses the potential relationship of this behaviour with surface hydroxylation and restructuring processes. The present study utilizes a time-resolved analysis to elucidate the dynamic surface evolution of nickel electrodes under practical alkaline HER conditions, thereby underscoring the significance of evaluating catalyst durability beyond the confines of short-term measurements. The findings presented herein contribute to a more realistic assessment of nickel-based electrodes for alkaline water electrolysis applications. Full article

Two-dimensional (2D) heterostructures offer tunable electronic structures and synergistic interactions that enhance electrocatalytic activity beyond the limits of single-component materials. However, the same atomically thin interfaces that enable high performance also introduce inherent mechanical, chemical, and electronic vulnerabilities, giving rise to complex and coupled degradation pathways. In this review, we provide a systematic overview of degradation in 2D heterojunction electrocatalysts during electrochemical operation, covering failure mechanisms, operando characterization, and stabilization strategies. Degradation is governed by interfacial strain accumulation, bubble-induced stress and delamination, galvanic corrosion, and selective leaching, while stability can be improved through interfacial coupling, structural confinement, and controlled reconstruction. These insights provide practical design guidelines for developing robust 2D heterostructures for electrochemical energy conversion. Full article

The oxygen evolution reaction (OER), serving as the anodic bottleneck in electrochemical water splitting for hydrogen production, severely limits the overall energy conversion efficiency due to its sluggish kinetics. Developing efficient and stable electrocatalysts based on earth-abundant elements is a critical challenge for advancing clean energy technologies. In recent years, silicate materials have demonstrated significant potential in alkaline OER catalysis owing to their unique stable silicon-oxygen tetrahedral framework and flexibly tunable metal-oxygen-silicon electronic coordination environments. This review systematically summarizes recent progress in silicate-based materials, including natural clay mineral supports such as halloysite, for OER electrocatalysis. It focuses on controllable synthesis strategies for silicate materials and provides an in-depth analysis of the regulation mechanisms for their electronic structure and surface properties through defect engineering, anion vacancy construction, and bimetallic/non-metallic heteroatom doping. Particular emphasis is placed on research pathways that utilize natural silicate clay minerals as both supports and silicon sources to construct high-performance composite catalytic materials via innovative structural design and interface engineering. Systematic studies indicate that precisely modulated silicate-based catalysts exhibit excellent electrochemical activity and long-term stability in the alkaline OER process. This review offers perspectives on the future development of efficient and stable silicate-based catalytic systems for renewable energy conversion. Full article

This study elucidates the mechanism enabling the low-voltage electrolysis of black liquor (BL) for integrated resource recovery. The process simultaneously generates protons at the anode via the oxidation of organics (OOR), which occurs at a lower potential than the oxygen evolution reaction (OER), and induces lignin precipitation. Concurrently, hydrogen and hydroxide ions are produced at the cathode through the hydrogen evolution reaction (HER). Driven by the electric field, sodium ions migrate from the anode to the cathode chamber, combining with hydroxide ions to form sodium hydroxide, thereby achieving the synchronous production of acid, alkali, hydrogen, and modified lignin in a single process. Using a platinum electrode, we conducted a mechanistic investigation through linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and detailed product analysis. The results show that overall efficiency is controlled by competition at the anode between OOR and OER, which directly determines proton yield. A critical trade-off exists between anodic proton generation and cathodic alkali recovery, driven by the competitive migration of protons and sodium ions across the cation-exchange membrane. The proton yield was highly dependent on the initial BL composition, with a characteristic peak observed under specific conditions. Conversely, the sodium hydroxide recovery rate was maximized when the anolyte pH remained high, minimizing competitive proton migration. This work provides fundamental insights into the interfacial mechanisms of BL electrocatalytic, establishing it as a versatile electrochemical biorefinery platform for simultaneous proton and alkali production from a renewable waste stream, beyond its role as a hydrogen source and lignin recovery. Full article

Methane, as an abundant and relatively clean resource, has primarily been converted into various chemical products via indirect conversion through synthesis gas, a mixture of CO and H₂. Recently, interest in direct methane conversion technologies with lower energy consumption has increased. Compared to research on methanol production via selective oxidation of methane, studies on the direct conversion of methane to acetic acid have been relatively scarce, but significant research progress has been made recently. This review classifies reports on the direct conversion of methane into acetic acid according to catalyst type (homogeneous vs. heterogeneous catalysts) and reaction conditions, and discusses the advantages and disadvantages of each approach. A relatively high yield of acetic acid can be achieved using CO as a carbonylating agent. However, the direct conversion of methane and CO₂ into acetic acid is more attractive from an environmental perspective. Recent advances in the field of electrocatalysis for this purpose are noteworthy. Other non-thermal catalytic methods, including photocatalysis, photoelectrocatalysis, and plasma processes, are also included. Based on the current state-of-the-art research trends in this field, future research directions are proposed. Full article

The literature data on the solid-state and surface chemistry of cobalt and cobalt–aluminum oxide and hydroxide systems are reviewed. The actual and potential applications of these materials in the fields of catalysis, electrocatalysis, photocatalysis, adsorption and sensor technologies are reviewed. A comprehensive analysis of the peculiar redox and acid–base properties of these cobalt-based systems, both at the solid–gas and at the solid–water solution interface, is conducted. Evidence is provided for the exceptional versatility of these systems and on their relevant potential for optimal applications, in particular, in several catalytic total oxidation reactions, in N₂O catalytic decomposition, in ammonia catalytic oxidation to NO, as electrocatalysts in water splitting reactions, as active elements in supercapacitors, and as precursors of cobalt metal-based systems. It is underlined that these systems could successfully substitute more critical and expensive noble metal-based systems in several technological fields. Full article

Cobalt disulfide (CoS₂) features highly active catalytic sites and is regarded as a promising candidate for electrocatalytic hydrogen evolution. In this study, molybdenum-doped cobalt disulfide (CoS₂:Mo) was synthesized via a facile hydrothermal approach. XRD analysis confirms that the obtained samples crystallize in a cubic pyrite structure, with diffraction peaks consistently shifting towards lower angles. SEM characterization reveals that the samples exhibit microrod-like morphologies with an average size of approximately 1 μm. Integrated analyses from XRD, XPS, and EDS mapping demonstrate that Mo is uniformly distributed across the surface and successfully doped into the CoS₂ lattice. Electrochemical measurements indicate that the CoS₂:Mo sample delivers a low overpotential of 122 mV and a Tafel slope of 128 mV dec⁻¹ at a current density of 10 mA cm⁻² in alkaline media, significantly surpassing the performance of pure CoS₂ and MoS₂. Moreover, the CoS₂:Mo exhibits an enhanced double-layer capacitance, with a C_dl value of 2.72 mF cm⁻², superior to that of pure CoS₂ (1.63 mF cm⁻²) and MoS₂ (0.31 mF cm⁻²). Mo doping enhances conductivity and active sites, thereby boosting electrocatalysis. This work presents an effective strategy for the development of cost-efficient and high-performance non-precious metal electrocatalysts. Full article

Functional materials based on LaCoSi and LaCuSi intermetallic compounds (IMC) were fabricated and tested in the electrocatalytic process of reducing nitrates to ammonia (NO₃RR). The method of arc melting in an argon atmosphere was used to synthesize the alloys. The synthesis process is described and analyzed in detail, and the difficulties and advantages are shown. It has been established that when using an LaCuSi-based IMC–alloy as an electrocatalyst, the reduction of nitrates is the predominant reaction. On the contrary, for the LaCoSi (IMC)–alloy electrocatalyst, NO₃RR and the hydrogen evolution reaction (HER) occur simultaneously. Full article

The acquisition of liquid energy sources and basic chemicals from washing water via Kolbe electrolysis is of great significance for achieving the goal of carbon-neutrality. However, oleophilic products tend to adhere to the platinum (Pt) electrode, which results in a shortened working life for Kolbe electrolysis. To address these issues, a novel method for endowing carbon fiber paper electrodes with underwater superoleophobic properties through simple electrodeposition is reported herein. The underwater superoleophobic electrodes improve the efficiency of the Kolbe electrolysis reaction, as oleophilic products can be easily removed from the electrode surface, thereby exposing more active reaction sites. Importantly, the underwater superoleophobic electrodes have fully demonstrated their capability of excellent electrochemical performance, stability, and durability. This work provides a novel approach for the design of high-performance electrodes in organic electro-catalysis. Full article

The nickel-derived metal–organic framework (MOF), Ni-BTB, synthesized from 4,4′,4″-benzene-1,3,5-tribenzoic acid (H₃BTB), was investigated as a multifunctional platform for enhanced energy applications including production and storage. In catalytic hydrogen generation by NaBH₄ hydrolysis, Ni-BTB attained a hydrogen generation rate (HGR) of 4640 mL H₂/g•min with 1 mg of catalyst, with an activation energy of 76.44 kJ/mol. Under optimized reaction conditions (60 °C, 20 mg catalyst, and 1 g NaBH₄), the HGR increased to 9542 mL H₂/g•min, while exhibiting high recyclability throughout four successive cycles. As a supercapacitor electrode, Ni-BTB achieved a specific capacitance of 156 F/g at 1 A/g and showed remarkable cycling stability, maintaining its capacitance after 10,000 charge–discharge cycles. Furthermore, Ni-BTB exhibited exceptional electrocatalytic activity for oxygen evolution reaction (OER), requiring only 106 mV overpotential to achieve 10 mA/cm², offering a time-of-flight (TOF) of 0.0585 s⁻¹ and demonstrating significant operational longevity of at least 12 h. These findings underscore Ni-BTB as a durable, reusable, and adaptable material for hydrogen production, energy storage, and electrocatalytic applications. Full article

Catalytic materials are central to the advancement of hydrogen generation technologies, playing a pivotal role in enabling sustainable, carbon-neutral energy systems. Hydrogen can be produced via electrochemical water splitting, thermochemical reforming, or photocatalysis—each imposing unique performance requirements on catalysts in terms of activity, selectivity, stability, and efficiency. While traditional noble metals (e.g., platinum, ruthenium, iridium) provide benchmark catalytic activity, their widespread use is hindered by scarcity, high cost, and limited long-term durability. Consequently, researchers have increasingly focused on earth-abundant alternatives such as transition metals (Ni, Co, Fe, Mo), alloys, metal oxides, carbides, sulfides, nitrides, and carbon-based systems. Among these, two-dimensional materials, particularly the MXene family, have attracted significant attention due to their metallic conductivity, layered structure, and tunable surface chemistry. These features enable rapid charge transfer and abundant active sites, making MXenes and related nanostructured catalysts promising for both the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) across a wide range of electrochemical conditions. Parallel efforts have integrated novel semiconductors, plasmonic nanomaterials, and hybrid heterostructures to improve the efficiency of solar-to-hydrogen energy conversion. This paper reviews the main types of catalytic materials used in hydrogen production, explains their design strategies and structure–performance relationships, and discusses key engineering challenges such as integrating renewable energy sources, scaling up manufacturing, and ensuring long-term durability in real-world systems. Future research goals are also highlighted, including the development of affordable non-noble catalysts, enhancing catalyst stability through surface and defect engineering, and coupling hydrogen production with circular economy principles, all of which are essential to making hydrogen generation more efficient, scalable, and cost-effective as the world transitions to clean and sustainable energy. Full article

Pt-based catalysts remain the most effective materials for the oxygen reduction reaction (ORR) at the cathode of proton exchange membrane fuel cells (PEMFCs); however, platinum scarcity and high cost severely limit the large-scale deployment of the technology. Improving catalytic activity and durability through precise control of nanoparticle morphology is therefore crucial for reducing costs and enhancing sustainability, enabling PEMFC widespread adoption. In this context, carbon-supported Pt-based nanoparticles with a 30 wt.% Pt loading were synthesized by an organometallic chemistry approach using hexadecylamine (HDA) as a stabilizer, allowing fine control over nanoparticle morphology. Two distinct synthesis pathways (one-pot and two-step procedures) were used to prepare platinum catalysts supported on KetjenBlack EC-300J (KB), and their influence on the electrocatalytic activity of the obtained nanomaterials was studied. Furthermore, the effect of HDA stabilization on catalyst performance was investigated. Directly synthesized Pt/KB catalysts exhibited similar ORR mass activity, regardless of whether or not HDA was present. Pt/KB prepared by the two-step procedure showed a significantly lower performance. Additionally, despite a larger loss of electrochemical surface area during an accelerated stress test compared to a commercial Pt/C reference, Pt^HDA/KB and Pt/KB catalysts maintained stable mass activity and limited specific activity degradation, highlighting the beneficial effect of nanoparticle stabilization in the presence of HDA on prolonged electrocatalyst cycling. Full article

The electrochemical reduction of CO₂ offers a sustainable approach to transforming carbon dioxide into value-added products when powered by renewable energy. However, current electrocatalysts lack efficiency and selectivity, hindering commercial application. Combining tin’s high formate selectivity with copper’s ability to reduce CO₂ via COOH* pathway offers a promising strategy. This synergy mitigates copper’s low selectivity, providing a cost-effective catalyst with enhanced performance over pure Sn-based systems. This work investigates CuSn bimetallic electrocatalysts synthesised by scalable electrodeposition onto gas diffusion layers to boost formate production. Catalytic performance and cell potential were evaluated at current densities ranging from 50 to 200 mA cm⁻² and varying Sn compositions. Catalysts with Sn content below 4% predominantly formed CO and H₂, but smaller particles and improved metal dispersion increased formate production. A catalyst containing 12% Sn achieved a maximum faradaic efficiency (FE) of 52% at 50 mA cm⁻² with an iR-corrected potential of −0.56 V vs. SHE. At 200 mA cm⁻², it exhibited a 30% FE for formate, along with 31% FE for CO and 9.3% FE for H₂, while other gases contributed to less than 4% FE, indicating potential as syngas feedstock. Higher Sn content, combined with smaller, well-distributed particles, effectively suppressed H₂, CO, and other by-products, highlighting a strong dependence of FE on Sn content and bimetallic distribution, demonstrating compositional tuning importance via electrodeposition. Full article