ChemElectroChem

Urea electrolysis in water is an attractive approach for ultrapure water production; however, the mechanism of electrochemical urea oxidation reaction (UOR) remains unclear. Here, we investigated UOR in MeCN–H 2 O mixed solution by changing the water ratio to reveal the role of water via hydrogen bonding with urea, gaining a mechanistic insight into UOR. The effect of water on UOR was evaluated and argued based on the analysis using 1 H NMR spectroscopy and electrochemical measurements. The results indicated that water molecules can weakly interact with urea (binding constant ( K ) is 0.18 M −1 ), which affect the current on differential pulse voltammetry (DPV). However, the electrochemical urea decomposition rate exhibited a maximum value at 1% water fraction in the range of 0%–30% water contents because the oxidation potential of urea showed a positive shift at higher water fraction. Then, nitrogen‐containing products (NH 4 + , NO 2 − , NO 3 − , and N 2 ) derived from electrochemical UOR were characterized by GC and HPLC in the range of 0%–30% water contents. Judging from these results, we have concluded that the reactivity of electrochemical UOR is dependent on the water fraction and the mechanism of electrochemical UOR is influenced by water due to the hydrogen bonding with urea.

Sodium vanadium phosphate (Na 3 V 2 (PO 4 ) 3 , NVP) is regarded as a promising cathode material for sodium‐ion batteries (SIBs). However, its practical application is severely impeded by the inherent low electronic conductivity. Carbon coating has been widely adopted to mitigate this limitation, primarily because it can form an interconnected conductive network. Herein, a series of NVP/C composites was synthesized via a sol‐gel method followed by calcination, employing oxalic acid, citric acid, sucrose, and ascorbic acid as distinct carbon sources. The influence of carbon sources on the degree of graphitization, specific surface area, uniformity, and morphology of the derived carbon coating was systematically investigated, and its correlation with the electrochemical performance was established. The results demonstrate that the composite prepared with citric acid as a carbon source (denoted as NVP/C‐N) exhibits the most favorable carbon layer structure, featuring large specific surface area, high graphitization, and uniform coverage, which contribute to its superior sodium storage properties. Specifically, it delivers a high reversible capacity, excellent rate capability, and outstanding cycling stability. This work elucidates the critical role of carbon source selection in determining the interfacial and conductive properties of NVP/C composites and provides practical guidance for the rational design of high‐performance NVP‐based cathodes for advanced SIBs.

Targeting the electrocatalytic CO2 reduction reaction (eCO2RR) using complex multimetal catalysts is a relatively new approach in electrocatalyst design. We explored the eCO2RR performance for lanthanoids and similar rare‐earth elements such as Gd, Sc, Tb, Nd, Sm, and Y as components in CuAgAl catalyst mixtures. Product selectivity is highly sensitive to the complexity of the catalysts (i.e. the number and identity of constituting elements) and the potential (activity) controlled by the compositions. Particularly, most of the Gd‐containing catalysts showed high Faradaic efficiency (FE) for C2+ products (FEC2+), >60%, at a current density of −400 mA cm−2. Using mean absolute error analysis, we investigated the correlation between multimetal composition, product selectivity, and required potential at a defined current density. The modulation in product distribution is likely promoted by the distinct properties of the multimetal catalysts. Operando Raman measurements of two multimetal catalysts (Cu80Ag5Al5Gd5Sm5 and Cu80Ag5Al5Nd5Sm5) revealed different mechanisms shown by the variations in the local alkalinity of the microenvironments and catalyst reconstruction, despite both catalysts exhibit an FEC2+ of 65%. Exploring multimetal catalysts expands the design space for elemental selection, allowing for distinct mechanisms that expand the understanding of selectivity modulation.

CO 2 capture and electrochemical conversion is a sustainable and circular process to produce carbon‐based chemicals. Capture of CO 2 can be achieved with amine‐based capturing agents, which have been reported in combination with homogeneous catalysts in solution. Amines have a range of effects on CO 2 reduction catalysis, depending on how they bind CO 2 , interact with the electrolyte, and with the catalyst, among other effects. The homogeneous complex Mn(bpy)(CO) 3 Br is a well‐studied catalyst that can selectively produce carbon monoxide (CO) or formate (HCOO – ), depending on the conditions. It has been demonstrated that the presence of amines can promote the selective formation of formic acid. In this work, Mn(bpy)(CO) 3 Br was immobilized on an electrode via supramolecular interactions. The resulting material was studied in electrochemical CO 2 reduction under aqueous conditions with and without triethanolamine (TEOA) present as a CO 2 capturing agent. We demonstrated that the presence of TEOA causes two effects: (1) a two‐fold increased catalytic activity in TON and (2) an increased selectivity for formate, from 36% to 60% Faraday efficiency. It showed that TEOA is an excellent additive for such catalytic systems and demonstrated the potential of expanding such catalytic systems to achieve more active and selective for aqueous CO 2 reduction.

Electrocatalytic nitrogen reduction is a vital strategy for green ammonia production. However, this is highly challenged by poor selectivity, and hence, the development of novel catalysts is scanty. The present research provides insight into the development of a new trimetallic alloy, CuAgMo, on multiwalled carbon nanotubes (MWCNT) for the nitrogen reduction reaction (NRR). Based on characterization techniques, the XRD shows successful growth of the trimetallic alloy on the MWCNT surface, and SEM–HRTEM images present the growth of CuAgMo nanoclusters on MWCNT and the existence of an interface. X‐ray Absorption Spectroscopy (XAS) analysis confirms the reduction of metals toward cluster formation that could act as an active site for nitrogen reduction. The resulting CuAgMo@CNT nanocluster exhibits high activity and selectivity, achieving a Faradaic efficiency of 38.8% at −1.5 V versus the reversible hydrogen electrode in a 0.5 M KOH electrolyte. Furthermore, chronoamperometry shows that the electrocatalyst demonstrated stability for 90 h, outperforming most recently reported electrocatalysts for NRR. The outcomes of the present research demonstrate a feasible pathway for the rational design of electrocatalysts for N2 fixation.

Finding suitable and inexpensive bifunctional materials that can act as adsorbents for crystal violet (CV) removal and as electrocatalysts for the electrochemical detection of urea remains one of the contemporary challenges. Waste valorization of spent wastewater nanoadsorbents is a promising route toward achieving circular economy guidelines. In this study, Zn–Fe layered double hydroxides (Zn–Fe LDHs) were synthesized and modified with three natural carbohydrate polymers chitosan, carrageenan, and cellulose using the coprecipitation method. The modified Zn–Fe LDHs were utilized as adsorbents for CV removal. Moreover, the biopolymer‐modified Zn–Fe LDHs both before and after CV adsorption were employed as electrocatalysts for the electrochemical detection of urea in an alkaline medium. The results showed that Zn–Fe LDH/chitosan exhibited the highest current density of 118.3 mA·cm−2 for urea detection. Furthermore, after CV adsorption, the catalytic current density of the urea adsorption enhanced to 137.2 mA·cm−2 with a stability of 96%. Additionally, the density functional theory (DFT) calculations revealed that the Zn–Fe LDH/chitosan/CV showed the lowest binding energy (ΔEbind) values in both gas phase (−18.12 kcal·mol−1) and water phase (−15.67 kcal·mol−1), indicating stronger interactions and suggesting that chitosan functionalization significantly enhances the adsorption capacity of LDH.

The sustainable fabrication of electrode materials using waste streams offers a promising pathway toward low‐cost and environmentally sustainable lithium‐ion batteries (LIBs). In this work, waste‐derived silicon (WD‐Si) recovered from end‐of‐life solar panels was used to fabricate a high‐performance Si/C composite anode. Waste rubber‐derived carbon nanoparticles (MWRC), synthesized through an energy‐efficient microwave‐assisted process, were incorporated as the carbon component. Mechanical milling was employed to reduce the particle size of WD‐Si, resulting in a broad particle‐size distribution with a significant submicron fraction after only 60 min of processing. Structural analyses confirmed that the milled Si retained high crystallinity while developing nanosized polycrystalline domains. Microwave‐assisted carbonization of waste rubber generated onion‐like carbon nanoparticles that were uniformly distributed along the rough surfaces and edges of the Si particles, forming a conductive and mechanically robust framework. The WD‐Si/MWRC composite exhibited significantly improved electrochemical performance compared with bare WD‐Si and commercial Si electrodes. The composite delivered initial discharge capacities of 2291.4, 1806.7, and 1280.1 mAh g−1 at 0.1, 0.2, and 0.5 C, respectively. After 50 cycles, the composite retained a reversible capacity of 663.8 mAh g−1, whereas commercial Si retained only 242.8 mAh g−1 under the identical conditions.

Growing global energy demands underscore the need for efficient, controllable synthesis of nanostructured hydrogen storage alloys. This work addresses the challenge of preparing composition‐ and morphology‐controlled La–Ni intermetallic nanoparticles via a one‐step electrochemical route in molten chlorides. We compared three electrochemical systems: La(III) reduction on an inert W electrode, co‐reduction of La(III) and Ni(II) on a W electrode, and La(III) reduction on a solid Ni electrode. Cyclic voltammetry, square wave voltammetry, and potentiostatic electrolysis at 647 K were employed to elucidate the deposition mechanisms. The results demonstrate that using a solid Ni cathode enables the direct formation of uniform LaNi5 nanoparticles with an average size of 100 nm and a well‐defined 1:5 La/Ni ratio, whereas the co‐deposition of La(III) and Ni(II) on a W electrode yields multiphase, agglomerated particles. The study reveals the critical role of the cathode material in directing phase selectivity and nanoparticle uniformity, providing a clean, one‐step alternative to conventional ball‐milling methods that yields LaNi5 nanoparticles with monodisperse distribution. This approach offers a practical pathway to synthesize high‐performance hydrogen‐storage nanomaterials with tailored compositions and morphologies.

Polymeric ionomers are essential to the catalyst layer (CL) of proton‐exchange membrane fuel cells (PEMFCs). This study compares two ionomers: the short‐side‐chain (SSC) N+125D and a high‐oxygen‐permeability experimental ionomer grade (EIG), the latter intended to enhance oxygen mass transport and the oxygen reduction reaction (ORR). The research evaluates ionomer–solvent interactions across various water/1‐propanol mixtures to ensure structural integrity and homogeneous distribution of the electrocatalyst. Multiple ink formulations were analyzed using advanced physical–chemical characterization to determine stability and quality. These insights guided the optimization of the electrode's microstructure for integration into membrane electrode assemblies (MEAs). By employing a multidisciplinary approach, the study correlates ink formulation and electrode morphology with electrochemical performance. This integrated methodology provides a robust framework for optimizing next‐generation PEMFC electrodes through a deeper understanding of ionomer behavior and structural influence within the CL.

Effective energy storage is crucial for maintaining a reliable supply of renewable energy. Supercapacitors serve as buffers, storing surplus energy during low demand and releasing it during peak times. Antimony‐based materials are promising candidates for supercapacitors due to their high‐power density and long cycle life. This study demonstrates that, although antimony‐based materials have previously been investigated in alkaline electrolytes, antimony sulfide iodide (SbSI), antimony sulfide (Sb2S3), and antimony oxide (Sb2O3) exhibit extremely poor stability in alkaline electrolytes such as NaOH and KOH. They react with these solutions to form compounds such as potassium antimony sulfide oxide (K3SbS3·(Sb2O3)3, PASO), which compromise supercapacitor performance. Although initially stable, PASO degrades quickly upon cycling, affecting long‐term storage applications. The study further investigates the stability of SbSI in different electrolytes through cyclic voltammetry, such as in neutral 0.5 M Li2SO4 and acidic 0.5 M H2SO4 electrolytes. SbSI shows improved structural stability in the acidic environment, while in the neutral electrolyte, its electrochemical response is less effective due to polarization and poor charge storage. These findings highlight the importance of electrolyte compatibility and post‐cycling characterization when evaluating antimony‐based materials for electrochemical energy storage.

The urgent transition toward a carbon‐neutral energy economy positions water electrolysis as a cornerstone for sustainable “green hydrogen” production. While noble‐metal catalysts define current benchmarks, their prohibitive costs and scarcity necessitate the development of robust, Earth‐abundant alternatives. This review provides a comprehensive analysis of advanced titanium (Ti)‐based architectures—specifically 2D MXenes, Magnéli phase suboxides (TinO2n−1), and single‐atom catalysts (SACs)—as transformative platforms for hydrogen and oxygen evolution reactions (HER/OER). We examine the synergistic effects of MXenes, where metallic conductivity and tunable surface terminations (Tx) optimize hydrogen adsorption energetics. Simultaneously, we highlight exceptional electrochemical stability and strong metal–support interactions (SMSI) of Magnéli phases, which effectively circumvent the “universal scaling relationship” bottlenecks in OER. Furthermore, we emphasize the integration of SACs on these Ti‐based supports, where engineering the local coordination environment maximizes atom utilization and intrinsically boosts catalytic activity. A strategic emphasis is placed on direct seawater electrolysis, highlighting the “chlorophobic” and self‐healing properties of Ti‐interfaces that ensure long term durability against chloride corrosion and mineral scaling. By integrating AI‐driven discovery and field‐scale engineering perspectives, this review provides a strategic roadmap for designing high‐performance, non‐noble metal‐based systems for industrial‐scale energy conversion, offering a viable solution to the long‐standing stability‐activity trade‐off in extreme environments.

On metal electrodes, excess charges accumulate on protrusions and dendrites and induce local dipole potentials, which affect the deposition of ions. In particular, alkali ions are deposited at negatively charged electrodes, since their potential of zero charge lies above the deposition potential. Using classical molecular dynamics, we have calculated the potential of mean force for the deposition of lithium ions on the tip of dendrites, which becomes much more favorable in the presence of a negative excess charge. The stochastic aspects of the deposition near dendrites have been investigated using a simple continuum model for the solution. Again, deposition near the tip of the dendrite is favored by a negative excess charge, while the base of the dendrite is shielded by the tip. These calculations provide an atomistic basis for a recently proposed model of dendrite formation.

Lignin, the second most abundant biopolymer, remains critically underutilized despite annual availability of 50 million tons. Electrochemical flow depolymerization combines energy‐efficient hydrogen production with selective lignin upgrading, offering a promising pathway to unlock this renewable aromatic feedstock. This mini‐review provides the first systematic analysis of flow‐based anodic lignin depolymerization studies, categorizing them into three strategic objectives: (1) oxygen evolution reaction (OER) substitution achieving cell voltage reductions of 0.2–0.45 V and 20%–40% energy savings, (2) nonselective fragmentation yielding oligomeric intermediates with molecular weight reductions up to 87%, and (3) selective monomer production up to 8 wt%. Critical deficiencies limiting industrial translation include incomplete lignin characterization, heterogeneous reactor descriptions, absence of standardized analytics, and prevalence of semibatch over continuous operation. Six research priorities are defined: (1) transition to continuous single‐pass or CSTR configurations with integrated product separation, (2) standardized test protocols and reference lignins with unified analytical methods, (3) comprehensive reactor design specifications, (4) development of stable noble metal‐free electrodes, (5) integration of continuous downstream separation technologies, and (6) systematic technoeconomic and life cycle assessments versus petrochemical benchmarks. This roadmap advances electrochemical lignin valorization from laboratory toward industrial readiness, essential for circular carbon economy strategies and chemical industry defossilization.

Acidic oxygen reduction is often discussed as if catalytic activation and mass transport were inseparable. Here, biomass‐derived carbon was used to examine these contributions through oxidation, ammonia annealing, and KOH activation. The onset potential is associated primarily with defect‐derived pz/π electronic states, whereas the maximum slope in the transport‐influenced region is associated with hierarchical pore accessibility and connectivity. Apparent electrochemically accessible surface area does not correlate significantly with onset potential in the six‐sample series, although it covaries with maximum slope; this covariance is attributed to pore accessibility rather than surface area itself. Multiscale X‐ray tomography of the optimized catalyst visualizes connected pore pathways from macro‐ to submicrometer scales, while the connected framework may be partly inherited from the rice‐husk precursor. The combined results support preferentially separate consideration of electronic activation and pore‐network accessibility for the acidic oxygen reduction reaction.

CO2 capture and electrochemical conversion is a sustainable and circular process to produce carbon‐based chemicals. Capture of CO2 can be achieved with amine‐based capturing agents, which have been reported in combination with homogeneous catalysts in solution. Amines have a range of effects on CO2 reduction catalysis, depending on how they bind CO2, interact with the electrolyte, and with the catalyst, among other effects. The homogeneous complex Mn(bpy)(CO)3Br is a well‐studied catalyst that can selectively produce carbon monoxide (CO) or formate (HCOO–), depending on the conditions. It has been demonstrated that the presence of amines can promote the selective formation of formic acid. In this work, Mn(bpy)(CO)3Br was immobilized on an electrode via supramolecular interactions. The resulting material was studied in electrochemical CO2 reduction under aqueous conditions with and without triethanolamine (TEOA) present as a CO2 capturing agent. We demonstrated that the presence of TEOA causes two effects: (1) a two‐fold increased catalytic activity in TON and (2) an increased selectivity for formate, from 36% to 60% Faraday efficiency. It showed that TEOA is an excellent additive for such catalytic systems and demonstrated the potential of expanding such catalytic systems to achieve more active and selective for aqueous CO2 reduction.

The electrochemical performance of a rutile with high niobium content (Ti 0.33 Nb 0.66 O 2 ) has been investigated as Li host material in Li half cells. Electrochemical features are typical of an intercalation pseudocapacitive material. It allows for a highly reversible specific capacity that is kept upon cycling (ca. 170 mAh g −1 after 200 cycles). This rutile can insert lithium through a solid solution down to 1 V, thus extending the solid solution region 0.2 V with respect to TiO 2 . On the other hand, the considerable increase in a lattice parameter due to the larger size of Nb widens the tunnel of the rutile structure, thus allowing for a faster insertion reaction. In this work, we report for the first time that the origin of the good performance of the Nb‐substituted TiO 2 rutiles can be attributed to a high lithium‐ion diffusion coefficient, in the order of 10 −10 – 10 −11 cm 2 s −1 . These are four orders of magnitude higher than that of TiO 2 rutile, thus explaining the intercalation pseudocapacitive behavior of the Nb‐derivatives of TiO 2 .

Rutile iridium dioxide (IrO 2 ) is a benchmark catalyst for heterogeneous electrooxidation reactions including the oxygen and chlorine evolution reactions (OER, CER), with broad applications such as water splitting, water treatment, chlor–alkali electrolysis, and chlorine‐mediated electrosynthesis reactions. Intrinsic OER activities and mechanisms are well established for low‐index crystallographic facets of IrO 2 . However, corresponding understanding of CER activity and selectivity is not yet well understood beyond its reactivity on the most thermodynamically stable (110) surface. Here, we experimentally show that the (110) and (100) facets have higher OER activity and lower CER selectivity compared to (101) and (001) IrO 2 epitaxial thin films. We compute unique facet dependence in the binding energies between reactive intermediates, where OER adsorbates are stabilized by bridging oxygen atoms on the least CER‐selective facets (110) and (100). The potential dependence and concentration dependence of experimental combined reaction rate order suggest that dynamic intermediate coverage changes in this regime drive differences in CER selectivity across facets. These facets show unique differences in activity between perchloric and sulfuric acid electrolytes, highlighting differences in competitive anion adsorption. These results indicate that facet engineering manipulates the local reaction environment to independently tailor OER and CER rates, providing control over selectivity in competitive electrooxidation conditions.

Direct carboxylation of C(sp 3 )H bonds with carbon dioxide (CO 2 ) offers an attractive route to value‐added carboxylic acids but remains challenging due to the inertness of both reaction partners. Here, we report a fundamentally distinct electrochemical strategy that enables carboxylation of dibenzylic C(sp 3 )H bonds using hydrogen atom transfer (HAT) species reductively generated at the cathode. This represents a rare example of C(sp 3 )H bond functionalization mediated by cathodically generated HAT species. In contrast to anodic HAT systems that require interelectrode diffusion of reactive intermediates, the present method allows all the elementary steps (HAT species generation, C(sp 3 )H bond cleavage, and CO 2 incorporation) to occur at the same cathode. Consequently, the reaction proceeds efficiently under mild conditions (room temperature, 1 atm CO 2 ) without requiring an external sacrificial redox reagent, affording carboxylation products in good yields (up to 69%) within a short reaction time (2 h). Mechanistic studies support a pathway involving sequential electron transfer‐chemical reaction (EC) and CO 2 ‐coupled electron transfer processes for HAT species generation. This work establishes a mechanistically defined platform for electrochemical dibenzylic C(sp 3 )H bond functionalization.

Sustainable chemical manufacturing relies on closing the carbon cycle by transforming CO 2 into useful products such as ethylene. Integrated CO 2 electrolysis enables direct use of CO 2 ‐rich absorbents, whereby efficient operation requires optimization of process conditions and cell design. This publication investigates the influence of flow field design, gas diffusion layer properties, catalyst loading, gas diffusion electrode compression, and membrane thickness on ethylene formation in a zero‐gap membrane electrode assembly electrolyzer using CO 2 ‐saturated potassium bicarbonate which is the CO 2 ‐loaded absorbent in the commercial potassium carbonate CO 2 scrubbing process. The results show that a flat, uniformly thin copper layer about 2 µm‐thick, placed next to a thin 20 µm anion exchange membrane, creates an enhancing microenvironment for C 2+ product formation with a maximum FE of 31% to ethylene at a current density of 50 mA cm −2 and a cell voltage of 5.2 V. These findings highlight the critical role of catalyst layer architecture and membrane selection in the effective conversion of CO 2 to C 2+ products. By focusing on the interplay between cell components and local reaction environments, this work advances the design of integrated CO 2 electrolyzers for efficient ethylene production, supporting the development of scalable, and sustainable carbon utilization.