Search Results (448)

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

Developing sustainable electrode materials from renewable biomass is important for improving the environmental sustainability of lithium-ion batteries (LIBs). Sugarcane bagasse lignin, an abundant agricultural byproduct, is a promising precursor for lignin-derived carbon anode materials, yet systematic comparative studies on catalyst-dependent structure evolution and LIB performance remain limited. In this study, lignin extracted from sugarcane bagasse by an ethanosolv process was converted into Fe- and Ni-catalyzed lignin-derived carbon materials via catalytic pyrolysis at 900 °C. The effects of catalyst type, metal-to-lignin ratio, and pyrolysis holding time on textural properties, structural features, and electrochemical behavior were systematically investigated. Among the studied conditions, the Fe-catalyzed sample prepared at a metal-to-lignin ratio of 1:2.5 and a holding time of 3 h (GLKL-2.5Fe-3h) exhibited the highest BET surface area (332.71 m² g⁻¹) and the most developed porous morphology. SEM, TEM, Raman, and XRD analyses indicated catalyst-dependent differences in pore development, carbon domain morphology, and local graphitic ordering, with Fe- and Ni-catalyzed samples following distinct structural evolution pathways. Electrochemical testing showed that GLKL-2.5Fe-3h delivered the highest initial discharge capacity (759 mAh g⁻¹), retained 165 mAh g⁻¹ after 500 cycles, and exhibited more favorable rate performance and lower apparent interfacial resistance than the other tested samples under the same conditions. In contrast, the Ni-catalyzed and solvothermally treated samples showed lower capacity retention and/or less favorable electrochemical behavior. These results demonstrate the strong effect of catalyst type on the structure-performance relationship of bagasse lignin-derived carbon anodes and support Fe-catalyzed lignin-derived carbon as a promising sustainable anode candidate for LIB applications. Full article

Microbial fuel cells (MFCs) are an emerging technology that converts the chemical energy stored in organic substrates into electrical energy using microorganisms as catalysts. However, their performance is often limited by the anode design and architecture. To address this, conductive anodes with well-defined pore sizes were manufactured via 3D printing and evaluated for electrical energy generation and wastewater treatment in microbial fuel cells. The maximum power density, coulombic efficiency, and accumulated biomass observed were 14.94 mW/m², 4.87 ± 0.56%, and 0.186 ± 0.025 g, respectively, for the anode with a 2.3 mm pore size. The maximum chemical oxygen demand (COD) removal efficiency was 86.98 ± 1.89% for the anode with a pore size of 1.6 mm. However, this difference was minimal and not significant compared to the anode with a 2.3 mm pore size, which achieved 85.77 ± 2.31%. Additionally, the lowest internal resistance observed was 1246.44 Ω, corresponding to the MFC equipped with the anode with a pore size of 2.3 mm. Taken together, these results indicate that, when using 3D-printed anodes with controlled architectures, an intermediate pore size, neither too large nor too small, provides an adequate balance between electrochemical performance and efficient wastewater treatment in microbial fuel cells. Full article

The ionic liquids are increasingly used as versatile media capable of reshaping the electrochemical environment for hydrogen production. Their wide electrochemical windows, thermal stability, and customizable solvation structures enable these liquids to tailor the electrode–electrolyte interface in such a way that the traditional alkaline and polymer-membrane systems cannot. These features allow for reductions in the hydrogen evolution overpotentials, improved catalyst stability, and effective suppression of gas crossover, positioning the ionic liquids as promising components for advanced electrolysis systems. Despite these benefits, their broader deployment remains constrained by certain challenges. The elevated viscosity and associated mass-transport limitations complicate the cell design and energy efficiency, whereas the cost and long-term stability of many ionic liquids limit their competitiveness in industrial hydrogen production. Also, the hydrolysable anions and other reactive species increase the burden, particularly in environments where moisture and anodic potential are present. As a result, the ionic liquids electrolysis has its most promising prospects in niche and hybrid configurations like the renewable integrated systems and configurations where the tailored interfacial chemistry and long operational lifetimes outweigh the investment cost and maintenance requirements. Future progress will depend on the development of greener, task-specific ionic liquids with improved stability and lower synthesis costs, alongside hybrid electrolyte designs that balance the unique interfacial benefits of ionic liquids with the practicality of aqueous systems. Advancing these materials from laboratory research to large-scale sustainable hydrogen production will require coordinated advances in the materials compatibility, device and infrastructural architecture, and techno-economic optimization. Full article

Ethylene glycol oxidation reaction (EGOR) is a promising anodic process to reduce the cell voltage compared with the oxygen evolution reaction (OER). Using ethylene glycol (EG) obtained from biomass-derived streams—such as cellulose, hemicellulose or lignocellulosic intermediates—and polyethylene terephthalate (PET) waste contributes to the development of circular-economy models. This study investigates EGOR on a non-noble NiCo bimetallic electrode, focusing on the effects of temperature and current density. The presence of EG reduces the initial potential by 240 mV at 25 °C, with a further 60 mV decrease at elevated temperatures, while the catalyst maintains high formate selectivity (>65%) across the tested conditions. Faradaic efficiency peaks at 100 mA cm⁻² due to the full oxidation of formate to CO₂ or the competing OER at higher current densities. There are no significant discrepancies between simulated and experimental faradaic efficiencies, although the presence of terephthalic acid (TPA) affects the shift in the electrode potential. Overall, these results highlight the relevance of EGOR for future applications in which EG derived from recycled plastics and renewable biomass can be electrochemically valorized within integrated biorefinery frameworks. Full article

Electrochemical ozone production (EOP) for generating ozone (O₃) directly in pure water presents a sustainable alternative to conventional methods. This review focuses on the advanced Membrane Electrode Assembly (MEA) electrolyzer, analyzing its fundamental thermodynamics, mechanisms, and key performance indicators. The core discussion centers on the MEA architecture, with an in-depth critique of anode catalysts (including cost-effective alternatives) and strategies to enhance O₃ selectivity over the competing oxygen evolution reaction. The role of the solid polymer electrolyte membrane is also examined. Furthermore, the review assesses how operational parameters and detection methods determine overall system efficiency and stability. It concludes by identifying challenges and future directions, underscoring the potential of MEA-based EOP for practical, on-site O₃ generation in pure water. Full article

Background: Traditional methods exhibit an extremely low removal efficiency for antibiotics in water, making an efficient and energy-saving approach urgently needed. Methods and Results: In this study, a novel catalytic approach based on the in situ generation of high-valent iron (Fe(IV)/Fe(V)) has been developed by adding biochar instead of modifying the electrode materials (in previous studies) for the efficient removal of sulfamethoxazole (SMX) from water. Fe(IV)/Fe(V) was produced by the anodic oxidation of low concentrations of Fe(III) and subsequently activated by nitrogen-doped corn stalk biochar (NBC). The results showed that the degradation efficiency increased from 50.83% to 90.67% within 60 min after the addition of nitrogen-modified biochar. The abundant defect structures, graphitic N and oxygen-containing functional groups in NBC endowed the catalyst with excellent activation capability. Quenching experiments and methyl phenyl sulfoxide (PMSO) probe experiments revealed that singlet oxygen (¹O₂) and Fe(IV)/Fe(V) were the main contributors to SMX degradation. Degradation pathways were inferred based on transformation products (TPs) and density functional theory (DFT) calculations. Ecotoxicity prediction using the ECOSAR program indicated that the TPs formed in the E/Fe(III)/NBC system exhibited markedly lower toxicity to aquatic organisms than the parent SMX. Furthermore, the E/Fe(III)/NBC system maintained a high degradation efficiency for SMX in real aquatic environments. Additionally, the E/Fe(III)/NBC system showed high removal rates for other sulfonamides such as sulfadiazine (SDZ), sulfamethoxypyridazine (SMP), sulfathiazole (STZ) and sulfadoxine (SDX). Conclusions: Overall, the E/Fe(III)/NBC system was demonstrated to be a highly efficient and sustainable technology for removing various antibiotics from water. Full article

Hierarchical In₂MnS₄ microflowers were synthesized via a hydrothermal approach and evaluated as multifunctional photo-/electrocatalysts for crystal violet (CV) dye degradation and methanol oxidation. The synthesis strategy produced three-dimensional flower-like architectures composed of nanoscale subunits with high crystallinity and uniform elemental distribution. Optical characterization revealed strong visible-light absorption with a bandgap of approximately 1.74 eV, indicating suitability for solar-driven photocatalysis. In₂MnS₄ microflowers achieved 96.6% degradation of CV dye within 100 min, whereas negligible activity was observed without the catalyst. Kinetic analysis followed a pseudo-first-order model with an apparent rate constant of 0.029 min⁻¹. The catalyst maintained stable performance over four consecutive cycles, confirming good recyclability. Photoelectrochemical measurements showed a stable photocurrent response and reduced charge-transfer resistance, indicating efficient separation and transport of photogenerated charge carriers. Furthermore, electrochemical measurements revealed increased anodic responses and sustained current behavior in the presence of methanol, suggesting an electrochemical response upon methanol addition. These results highlight In₂MnS₄ microflowers as promising visible-light-responsive materials for environmental remediation and energy-related catalytic applications. Full article

Noble metal-catalyzed C–H activation has transformed synthetic methodology by enabling direct modification of inert C–H bonds with high levels of efficiency, selectivity, and functional group tolerance. This mini-review provides a focused overview of the mechanistic foundations and emerging advances in C–H functionalization mediated by ruthenium, iridium, rhodium and palladium catalysts. Key activation modes including oxidative addition, concerted metalation deprotonation (CMD), and electrophilic pathways are discussed alongside the roles of high-valent intermediates and ligand control in determining reactivity and regioselectivity. Special emphasis is placed on recent electrochemical strategies, where anodic oxidation replaces traditional chemical oxidants, granting access to unique redox manifolds and expanding the scope of C–C, C–N, C–O, and C–X bond-forming reactions. Representative transformations highlight the versatility of noble metals in constructing heterocycles, enabling enantioselective processes, and facilitating late-stage functionalization of complex molecules. Current challenges and future perspectives are outlined, including the need for improved nondirected activation, deeper mechanistic insight, and enhanced scalability. Collectively, this review underscores the central role of noble metals in advancing sustainable and innovative C–H functionalization chemistry. Full article

Paired electrolysis represents a more environmentally sustainable and efficient approach for converting agroforestry biomass-derived 5-hydroxymethylfurfural (HMF) and furfural (FUR) into valuable fine chemicals and fuel additives. A critical challenge in developing paired electrolysis systems for furanal compounds is finding the optimal potential matching between the anode and the cathode. One solution is to reduce the potential sensitivity of the anode so that the paired electrolysis system can be regulated only by the cathode potential. In this study, we employed the homogeneous catalyst 4-acetamido-TEMPO (ACT) to facilitate oxidation reaction at the anode, enabling the potential sensitivity of the anode to be reduced. The results displayed the furanal substrates oxidation proceeds through a non-electrochemical chemical reaction with the active oxoammonium cation (ACT⁺), rather than being directly governed by the anode potential. The paired electrolysis system exhibited enhanced catalytic performance, with a total faradaic efficiency of 190.69% and 189.11% in the FUR and HMF paired electrolysis setup, respectively. Furthermore, this system demonstrated excellent stability, maintaining a total faradaic efficiency of over 167.64% after multiple successive cycles. Additionally, the solar-driven paired electrolysis system showed commendable substrate conversion capabilities, achieving a total faradaic efficiency of 187.89%, comparable to that of the electrically driven system. The mechanisms of the ACT electro-oxidation of furanal compounds and the construction of paired electrolysis systems for furanal compounds were proposed and discussed. This work aims to enhance electrical energy efficiency and underscore the potential of paired electrochemical catalysis for sustainable biomass conversion in the green economy. Full article

The flue gas of a copper smelting plant contains high-concentration SO₂, which could be used for sulfuric acid production via a catalytic oxidation approach. Coal as a reducing agent during pyrometallurgical copper refinement in an anode furnace leads to high-concentration CO in the flue gas. High concentrations of CO not only compete for oxygen consumption but also reduce the activity of oxidation catalysts, thereby severely hindering the resource recovery of SO₂ from flue gas. This problem may be resolved via installing a combustion chamber downstream, which introduces air to assist with CO oxidation. However, the complex composition of anode furnace flue gas affects CO combustion reactions, and the flue gas temperature may decrease from 1150 °C to 600 °C during flow to the combustion chamber, making CO combustion difficult. Additionally, significant air leakage could account for more than 60% of the total flue gas volume, which makes it difficult to determine the flue gas volume and severely hinders the calculation of the required oxygen dosage for the combustion chamber. In this study, an anode furnace with single production copper output of the 160-ton class was selected, and its flue gas volume as well as the required air supply for complete CO combustion were calculated based on the CO concentration via adopting the elements conservation law. When CO accounts for 3–10% of the total flue gas volume, the total flue gas flow volume ranges from 6800.3 to 7637.3 Nm³/h during reduction in an anode furnace, and the required air supply for CO burn-off ranges from 545.1 Nm³/h to 1617.9 Nm³/h. Based on the flue gas composition and conditions in the combustion chamber, the influences of the temperature and CO₂ and H₂O concentrations on CO oxidation were systematically investigated via using a tube reactor experimental system. CO oxidation initiated at 500 °C and reached near-complete conversion (99.9%) at 800 °C. The addition of 5% H₂O notably enhanced the reaction, reducing the T₅₀ (50% conversion temperature) from 675 °C to 650 °C. Conversely, a marked suppression was observed with 6.09% CO₂ at 650 °C, where the oxidation rate dropped sharply from 50.27% to 27.75%. A dedicated examination of O₂ then confirmed that increasing its concentration effectively enhanced combustion completeness under the optimized conditions. At 650 °C, the CO oxidation rate increased from 24% to 56% as the O₂ concentration rose from 17.58% to 41%, whereas a further increase in O₂ to 51% suppressed the rate to 39%. Full article

Direct borohydride fuel cells (DBFCs) are emerging as a promising source of clean energy; however, their performance depends heavily on efficient anode catalysts for the oxidation reaction of sodium borohydride (BOR). In this study, we developed and tested the Au–NiZn/Ti electrocatalyst designed to improve the performance of DBFCs. Electrodeposition and alkaline leaching were utilized to transform a zinc-rich nickel coating into a porous dendritic structure on a titanium substrate. By adding a small amount of gold crystallites through galvanic displacement, the surface roughness and the number of active sites available for the reaction were significantly increased. Electrochemical tests confirmed that this modification enhances BOR and effectively suppresses unwanted side reactions like hydrogen evolution. The resulting catalyst demonstrated high stability, maintaining over 88% of its current density during extended operation. Ultimately, the study positions this gold-modified material as a cost-effective and durable solution for clean energy conversion technologies. Full article

The current work examines the impact of isopropanol (IPA) on the electrochemical characteristics of nickel foam and Pd-modified Ni foam electrodes in a 0.1 M NaOH medium, with respect to the kinetics of the hydrogen evolution reaction (HER) over the temperature range of 20–40 °C. Comparative HER/IPA examinations are presented for a highly catalytic polycrystalline Pt electrode. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and cathodic Tafel polarization experiments were carried out in this work, where the IPA concentrations ranged from 1.0 × 10⁻⁵ to 1.0 × 10⁻³ M. The introduction of small amounts of isopropyl alcohol into the working electrolyte noticeably facilitated the catalytic efficiency of the hydrogen evolution reaction on the surface of Ni foam electrodes. This is most likely related to the fact that IPA molecules undergo partial electrooxidation to acetone (qualitatively confirmed by GC-MS analysis) during initial CV cycling, which is believed to significantly diminish the surface tension phenomenon during the HER, thus promoting hydrogen bubble separation from the electrode surface. It should also be noted that acetone will continuously be produced at the Pt anode, making it essential to consider further migration of (CH₃)₂CO molecules to the working cell compartment. Most importantly, isopropanol was found not to undergo significant surface electrosorption on the nickel foam-based catalysts, which could otherwise significantly inhibit the hydrogen evolution reaction On the contrary, the presence of IPA in the electrolyte solution seems to have a detrimental effect on the kinetics of both the HER and the UPDH (underpotential deposition of H) processes on the surface of the polycrystalline Pt electrode, which is a superior electrochemical catalyst for HER, but highly susceptible to surface contamination. Full article

The continuous emission of persistent and bioaccumulative pollutants into aquatic environments has become a critical global issue. Among these, per- and polyfluoroalkyl substances (PFASs) are of particular concern due to their exceptional stability, extensive industrial use, and adverse impacts on ecosystems and human health. Their resistance to conventional physical, chemical, and biological treatments stems from the strength of the carbon–fluorine bond, which prevents efficient degradation under standard conditions. This review provides a concise and updated assessment of emerging advanced oxidation processes (AOPs) for PFAS remediation, with emphasis on heterogeneous photocatalysis and electrochemical oxidation. Photocatalytic systems based on In₂O₃, Bi-based oxyhalides, and Ga₂O₃ exhibit high PFAS degradation under UV light, while heterojunctions and MOF-derived catalysts improve defluorination under solar irradiation. Electrochemical oxidation—particularly using Ti₄O₇ reactive electrochemical membranes and BDD anodes—achieves near-complete mineralization with comparatively low specific energy demand. Energy consumption (E_EO) was calculated from literature data for UV- and simulated-solar-driven photocatalytic systems, enabling a direct comparison of their energy performance. Although solar-driven processes offer clear environmental advantages, they generally exhibit higher E_EO values, mainly due to lower apparent quantum yields and less efficient utilization of the incident solar photons compared to UV-driven systems. Hybrid systems coupling photocatalysis and electro-oxidation emerge as promising strategies to enhance degradation efficiency and reduce energy requirements. Overall, the review highlights key advances and future research directions toward scalable, energy-efficient, and environmentally sustainable AOP-based technologies for PFAS removal. Full article

The plasma-catalytic conversion of CO₂ is a promising route toward sustainable fuel and chemical production under mild operating conditions. However, many aspects still need to be better understood to improve performance and better understand the catalyst-plasma synergies. Among them, one aspect concerns understanding whether photons emitted by plasma discharges could induce changes in the catalyst, thereby promoting interaction between plasma species and the catalyst. This question was addressed by investigating the CO₂ splitting reaction in a planar dielectric barrier discharge (pDBD) reactor using titania-based catalysts that simultaneously act as discharge electrodes. Four systems were examined feeding pure CO₂ at different flow rates and applied voltage: bare titanium gauze, anodically formed TiO₂ nanotubes (TiNT), TiNT decorated with Ag–Au nanoparticles (TiNTAgAu), and TiNT supporting Ag–Au nanoparticles coated with polyaniline (TiNTAgAu/PANI). The TiNTAgAu exhibited the highest CO₂ conversion (35% at 10 mL min⁻¹ and 5.45 kV) and the most intense optical emission, even in the absence of external light irradiation, suggesting that the improvement is primarily attributed to plasma–nanoparticle interactions and self-induced localized surface plasmon resonance (si-LSPR) rather than conventional photocatalytic pathways. SEM analyses indicated severe plasma-induced degradation of TiNT and TiNTAgAu surfaces, leading to performance decay over time. In contrast, the TiNTAgAu/PANI catalyst retained structural integrity, with the polymeric coating mitigating plasma etching while maintaining competitive efficiency. There is thus a complex behavior with catalytic performance governed by nanostructure stability, plasmonic enhancement, and the interfacial protection. The results demonstrate how integrating plasmonic nanoparticles and conductive polymers can enable the rational design of durable and efficient plasma-photocatalysts for CO₂ valorization and other plasma-assisted catalytic processes. Full article