Search Results (918)

The global transition toward renewable energy sources has intensified in response to escalating environmental challenges. Nevertheless, the inherent intermittency and instability of renewable energy necessitate the development of reliable energy storage technologies. Supercapacitors are particularly notable for their high specific capacitance, rapid charge and discharge capability, and exceptional cycling stability. Concurrently, the increasing demand for efficient and sustainable energy storage systems has stimulated interest in multifunctional electrode materials that integrate electrocatalytic activity with electrochemical energy storage. Two-dimensional transition metal dichalcogenides (TMDs), owing to their distinctive layered structures, large surface areas, phase state, energy band structure, and intrinsic electrocatalytic properties, have emerged as promising candidates to achieve dual functionality in electrocatalysis and electrochemical energy storage for asymmetric supercapacitors (ASCs). Specifically, their unique electronic properties and catalytic characteristics promote reversible Faradaic reactions and accelerate charge transfer kinetics, thus markedly enhancing charge storage efficiency and energy density. This review highlights recent advances in TMD-based multifunctional electrodes. It elucidates mechanistic correlations between intrinsic electronic properties and electrocatalytic reactions that influence charge storage processes, guiding the rational design of high-performance ASC systems. 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 ethanol oxidation reaction (EOR) is a key process for direct ethanol fuel cells (DEFCs), offering a high-energy-density and carbon-neutral pathway for sustainable energy conversion. However, the practical implementation of DEFCs is significantly hindered by the EOR due to its sluggish kinetics, complex multi-electron transfer pathways, and severe catalyst poisoning by carbonaceous intermediates. This review provides a comprehensive and mechanistically grounded overview of recent advances in EOR electrocatalysts, with a particular emphasis on the structure–activity relationships of noble metals (Pt, Pd, Rh, Au) and non-noble metals. The effects of catalyst composition, surface structure, and electronic configuration on C–C bond cleavage efficiency, product selectivity (C1 vs. C2), and CO tolerance are critically evaluated. Special attention is given to the mechanistic distinctions among different metal systems, highlighting how these factors influence reaction pathways and catalytic behavior. Key performance-enhancing strategies—including alloying, nanostructuring, surface defect engineering, and support interactions—are systematically discussed, with mechanistic insights supported by in situ characterization and theoretical modeling. Finally, this review identifies major challenges and emerging opportunities, outlining rational design principles for next-generation EOR catalysts that integrate high activity, durability, and scalability for real-world DEFC applications. Full article

The development of effective catalysts for the oxygen reduction reaction (ORR) is crucial for improving the performance of fuel cells. Efficient carbon-supported Pt-Co nanocatalysts were successfully prepared by a generic two-step method: (i) electroless deposition of a Co-P coating on Vulcan XC72R carbon powder and (ii) subsequent spontaneous partial galvanic replacement of Co by Pt, upon immersion of the Co/C precursor in a chloroplatinate solution. The prepared Pt-Co particles (of a core-shell structure) are dispersed on a Vulcan XC-72 support, forming agglomerates made of nanoparticles smaller than 10 nm. The composition and surface morphology of the samples were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS) as well as transmission electron microscopy (TEM). The crystal structures of the Co-P/C precursor and Pt-Co/C catalyst were investigated by X-ray diffraction (XRD). XPS analysis was performed to study the chemical state of the surface layers of the precursor and catalyst. The electrochemical behavior of the Pt-Co/C composites was evaluated by cyclic voltammetry (CV). Linear sweep voltammetry (LSV) experiments were used to assess the catalytic activity towards the ORR and compared with that of a commercial Pt/C catalyst. The Pt-Co/C catalysts exhibit mass-specific and surface-specific activities (of j_m = 133 mA mg⁻¹ and j_esa = 0.661 mA cm⁻², respectively) at a typical overpotential value of 380 mV (+0.85 V vs. RHE); these are superior to those of similar electrodes made of a commercial Pt/C catalyst (j_m = 50.6 mA mg⁻¹; j_esa = 0.165 mA cm⁻²). The beneficial effect of even small (<1% wt.%) quantities of Co in the catalyst on Pt ORR activity may be attributed to an optimum catalyst composition and particle size resulting from the proposed preparation method. Full article

Intermetallic compounds (IMCs) can be used to create catalysts with unsurpassed practical characteristics, including for demanding and stable electrochemical reactions such as nitrogen reduction (NRR), nitrate reduction (NO₃RR), and nitrite reduction (NO₂RR), which can serve as a replacement for the industrial Haber–Bosch process. An urgent task is to develop efficient electrocatalysts using low-cost base metals, with partial or complete replacement of noble metals. This short perspective review focuses primarily on the latest work from 2024–2025 and serves as a guide and starting point for a wide readership on the IMC applications of catalysts. Full article

Aerogels (AGs) are highly porous, low-density, disordered, ultralight macroscopic materials with immense surface areas. Traditionally synthesized using aqueous sol–gel chemistry, starting by molecular precursors, the nanoparticles (NPs) dispersions gelation method is nowadays the most used procedure to obtain AGs with improved crystallinity and broader structural, morphological and compositional complexity. The Sol–gel process consists of preparing a solution by hydrolysis of different precursors, followed by gelation, ageing and a drying phase, via supercritical, freeze-drying or ambient evaporation. AGs can be classified based on various factors, such as appearance, synthetic methods, chemical origin, drying methods, microstructure, etc. Due to their nonpareil characteristics, AGs are completely different from common NPs, thus covering different and more extensive applications. AGs can be applied in supercapacitors, acoustic devices, drug delivery, thermal insulation, catalysis, electrocatalysis, gas absorption, gas separation, organic and inorganic xenobiotics removal from water and air and radionucleotides management. This review provides first an analysis on AGs according to data found in CAS Content Collection. Then, an AGs’ classification based on the chemical origin of their precursors, as well as the different methods existing to prepare AGs and the current optimization strategies are discussed. Following, focusing on AGs of inorganic origin, silica and metal oxide-based AGs are reviewed, deeply discussing their properties, specific synthesis and possible uses. These classes were chosen based on the evidence that they are the most experimented, patented and marketed AGs. Several related case studies are reported, some of which have been presented in reader-friendly tables and discussed. Full article

The hierarchical porosity and active sites of porous carbon materials have significant impacts on the oxygen reduction reaction (ORR) process. The heteroatom-doped porous carbon materials (Z67-900, Z8-900, Z11-900, Z12-900) were synthesized by pyrolysis of ZIFs to reveal the synergistic effect of hierarchical porosity and Co-N_x sites. The structures of prepared materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and nitrogen adsorption. The results of electrocatalytic performance show that Z67-900 has the best performance among the four materials prepared. The onset potential (E₀) of Z67-900 is close to commercial Pt/C (20%), and the half-wave potential (E_1/2) of Z67-900 is 80 mV positive than that of Pt/C in an O₂-saturated 0.1 M KOH solution (1600 rpm) with sweep rate of 5 mV·s⁻¹. Moreover, Z67-900 has better methanol resistance. The hierarchical pore structure of Z67-900 facilitates mass transfer, while the Co-N_x sites provide active catalytic centers. This study provides a solid foundation for the rational design of highly efficient ZIF-derived heteroatom-doped catalysts. Full article

Electrochemical reduction processes enable the CO to be converted into a useful chemical fuel. Our study employs density functional theory calculations to analyze the (110) facets of the transition metal carbide surfaces for CO capture, incorporating the Mars–van Krevelen (MvK) mechanism. All the possible adsorption sites on the surface, including carbon, metal, and bridge sites, were fully investigated. The findings indicate that the carbon site is more active relative to the other adsorption sites examined. The CO hydrogenation paths have been comprehensively investigated on all the surfaces, and the free energy diagrams have been constructed towards the product. The results conclude that the TiC is the most promising candidate for the formation of methane, exhibiting an onset potential of −0.44 V. The predicted onset potential for CrC, MoC, NbC, VC, WC, ZrC, and HfC are −0.86, −0.61, −0.61, −0.93, −0.87, −0.61, and −0.81 V, respectively. Our calculated results demonstrate that MvK is selectively relevant to methane synthesis. Additionally, we investigated the stability of these surfaces against decomposition and conversion to pure metals concerning thermodynamics and kinetics. It was found that these carbides could remain stable under ambient conditions. The exergonic adsorption of hydrogen on carbon sites, requiring smaller potential values for product formation, and stability against decomposition indicate that these surfaces are highly suitable for CO reduction reactions using the MvK mechanism. Full article

The development of high-performance electrochemical sensors is crucial for ammonia–nitrogen detection. Therefore, in this study, we successfully prepared one ternary PtNiCo nanosheet via the one-step electrodeposition technique. The ratio of H₂PtCl₆·6H₂O, Ni(NO₃)₂·6H₂O and Co(NO₃)₂·6H₂O and electrodeposition time were controlled. Under optimal conditions, Pt₆Ni₂Co₂-2000 demonstrated outstanding electrocatalytic performance, exhibiting a high oxidation peak current of 45.27 mA and excellent long-term stability, retaining 88.09% of its activity after 12 h. Furthermore, the sensing performance of Pt₆Ni₂Co₂-2000 was evaluated, revealing high sensitivity (10.01 μA μM⁻¹), a low detection limit (0.688 µM), strong anti-interference capability, great reusability, great reproducibility, and remarkable long-term stability. Additionally, recovery tests conducted in tap water, lake water, and seawater yielded highly favorable results. This study demonstrated that designing Pt-based alloys can not only enhance the electrochemical performance of Pt but also serve as an effective strategy for improving electrocatalytic ammonia oxidation and ammonia–nitrogen detection. Full article

Water contamination by emerging pollutants poses a significant environmental challenge, demanding innovative treatment technologies beyond conventional methods. Advanced oxidation processes (AOPs) utilizing niobium-based catalysts, particularly niobium oxide (Nb₂O₅) and its modified forms, are prominent due to their high chemical stability, effective reactive oxygen species (ROS) generation, and versatility. This review systematically examines recent advancements in Nb₂O₅-based catalysts across various AOPs, including heterogeneous photocatalysis, electrocatalysis, and Fenton-like reactions, highlighting their mechanisms, material modifications, and performance. Following PRISMA and InOrdinatio guidelines, 381 papers were selected for this synthesis. The main findings indicate that niobium incorporation enhances pollutant degradation by extending light absorption, reducing electron–hole recombination, and increasing ROS generation. Structural modifications such as crystalline phase tuning, defect engineering, and the formation of heterostructures further amplify catalytic efficiency and stability. These catalysts demonstrate considerable potential for water treatment, effectively degrading a broad range of persistent contaminants such as dyes, pharmaceuticals, pesticides, and personal care products. This review underscores the environmental benefits and practical relevance of Nb₂O₅-based systems, identifying critical areas for future research to advance sustainable water remediation technologies. Full article

The co-electrolysis of nitrate and CO₂ can contribute to urea production with low carbon-oxide emission rate and at the same time reduce NO₃⁻ to extremely low permissible concentrations. It was found that Ag and Fe particles, as thin catalytic layers, can potentially be used for the joint reduction of NO₃⁻ and CO₂ under benign ambient conditions. The linear voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and electron scanning microscopy were used. The Fe/C electrocatalyst exhibits superior current density stability at −1.2 V vs. Ag/AgCl, whereas Ag/C electrocatalyst shows noticeable degradation over time. This reaction is necessary both for the removal of nitrates from wastewater and for the capture of carbon dioxide, which makes it one of the important applications of sustainable chemistry. Full article

Extraction processes of alginates from Sargassum spp. generate a substantial number of solid residues that are commonly discarded. This study explores the sustainable transformation of these residues into nitrogen-doped biocarbon through chemical activation with KOH and nitrogen doping using urea. XRD, FTIR, SEM-EDX, Raman spectroscopy, BET surface area analysis, XPS, and CHNS elemental analysis were used to characterize the materials. The doped and activated biocarbon (BDA) demonstrated excellent physicochemical properties, including a specific surface area of 1790 m² g⁻¹ and a mesoporous structure. Electrochemical evaluation in alkaline media revealed a current density of −4.37 mA cm⁻², an onset potential of 0.922 E vs. RHE, and a half-wave potential of 0.775 E vs. RHE. Koutecky–Levich analysis indicated a two-electron reduction pathway. The superior performance was attributed to the synergistic effects of high surface area, nitrogen functionalities (pyridinic-N and pyrrolic-N), and enhanced accessibility of active sites. These results highlight the potential of waste-derived, nitrogen-doped biocarbon as a sustainable and low-cost alternative for ORR electrocatalysis in alkaline fuel cells. Full article

Carbon-based metal-free catalysts, particularly those such as biomass-derived mesoporous activated carbon (AC) nanostructures, hold great promises for cost-effective and sustainable electrocatalysis for enhancing hydrogen evolution reaction (HER) performance in green energy technology. Neem and ginkgo leaves are rich in bioactive compounds and self-doping heteroatoms with naturally porous structures and act as a low-cost, sustainable biomass precursors for high-performance HER catalysts. In this study, mesoporous AC nanoflakes and nanosponges were synthesized using biomass precursors of neem and ginkgo leaves through a KOH activation process. Notably, AC nanosponges derived from ginkgo leaves exhibited outstanding physicochemical characteristics, including a sponge-like porous morphology with a large specific surface area of 1025 m²/g. For electrochemical evaluation in 0.5 M H₂SO₄, the G-AC sample revealed superior electrocatalytic HER performance, with a remarkably low overpotential of 26 mV at −10 mA/cm², a small Tafel slope of 24 mV/dec, and long-term durability over 30 h. These results depict biomass-derived mesoporous AC nanosponges to hold substantial potential for highly efficient hydrogen production, contributing significantly to the advancement of eco-friendly energy solutions. Full article

The electrochemical reduction in CO₂ (CO2RR) to syngas and value-added hydrocarbons offers a promising route for sustainable CO₂ utilization. This work develops tuneable Cu-Sn bimetallic catalysts via electrodeposition, optimized for CO2RR in a zero-gap flow cell fed with CO₂-saturated KHCO₃ solution, a configuration closer to industrial scalability than conventional H-cells. By varying electrodeposition parameters (pH, surfactant DTAB, and metal precursors), we engineered catalysts with distinct selectivity profiles: Cu-Sn(B), modified with DTAB, achieved 50% Faradaic efficiency (FE) to CO at −2.2 V and −50 mA·cm⁻², outperforming Ag-based systems that require higher overpotentials. Meanwhile, Cu-Sn(A) favoured C₂H₄ (35% FE at −100 mA·cm⁻²), and Cu-Sn(C) shifted selectivity to CH₄ (26% FE), demonstrating product tunability. The catalysts’ performance stems from synergistic Cu-Sn interactions and DTAB-induced morphological control, as revealed by SEM/EDX and electrochemical analysis. Notably, all systems operated at lower voltages than literature benchmarks while maintaining moderate CO₂ utilization (32–49% outlet). This study highlights the potential of electrodeposited Cu-Sn catalysts for energy-efficient CO2RR, bridging the gap between fundamental research and industrial application in syngas and hydrocarbon production. Full article

This work focuses on the sustainable green synthesis of magnetic iron oxide nanoparticles (Fe₃O₄NPs) using bioreductants derived from orange peel extracts for application in the efficient oxygen evolution reactions (OER). The synthesized catalysts were characterized using X-ray diffraction analysis, field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The Fe₃O₄NPs exhibit a well-defined spherical morphology with a larger Brunauer–Emmett–Teller surface area and a significant electrochemically active surface area. The green synthesis using orange peel extracts leads to an excellent electrocatalytic activity of the apparent spherical Fe₃O₄NPs (diameter of 9.62 ± 0.07 nm), which is explored for OER in an alkaline medium (1.0 M KOH) using linear-sweep and cyclic voltammetry techniques. These nanoparticles achieved a benchmark current density of 10 mA cm⁻² at a low overpotential of 0.3 V versus RHE, along with notable durability and stability. The outstanding OER electrocatalytic activity is attributed to their unique morphology, which offers large surface area and an ideal porous structure that enhances the adsorption and activation of reactive species. Furthermore, structural defects within the nanoparticles facilitate efficient electron transfer and migration of these species, further accelerating the OER process. Full article