Search Results (101)

The core challenge of integrated carbon capture and utilization (ICCU) technology lies in developing electrolytes that combine efficient carbon dioxide (CO₂) capture with electrocatalytic conversion capabilities. This review analyzes the structure–performance relationship between electrolyte properties and CO₂ electrochemical reduction (eCO₂RR), revealing the key regulatory mechanisms. Research shows that the performance of bicarbonate electrolytes heavily depends on the cation type, where Cs⁺ can achieve over 90% CO selectivity by suppressing the hydrogen evolution reaction (HER) and stabilizing reaction intermediates, though its strong corrosiveness limits practical applications. Although amine absorbents excel in carbon capture (efficiency > 90%), they tend to undergo competitive adsorption during electrocatalysis, making formic acid the primary product (FE = 15%); modifying electrodes with ionomers can enhance their activity by 1.15 times. Ionic liquids (ILs) demonstrate unique advantages due to their tunability: imidazolium-based ILs improve formate selectivity to 85% via carboxylate intermediate formation, while amino-functionalized task-specific ILs (TSILs) achieve a 1:1 stoichiometric CO₂ absorption ratio. Recent breakthroughs reveal that ternary IL hybrid electrolytes can achieve nearly 100% CO Faradaic efficiency (FE) through microenvironment modulation, while L-histidine additives boost CH₄ selectivity by 23% via interface modification. Notably, constructing a “bulk acidic–interfacial neutral” pH gradient system addresses carbonate deposition issues in traditional alkaline conditions, increasing C₂₊ product efficiency to 50%. Studies also highlight that cation–anion synergy (e.g., K⁺/I⁻) significantly enhances C-C coupling through electrostatic interactions, achieving 97% C₂₊ selectivity on Ag electrodes. These findings provide new insights for ICCU electrolyte design, with future research focusing on machine learning-assisted material optimization and reactor engineering to advance industrial applications. Full article

ZnO/WO₃ coatings were synthesized by the plasma electrolytic oxidation of zinc in an alkaline phosphate electrolyte (supporting electrolyte, SE) with the addition of WO₃ particles or tungstosilicic acid (WSiA, H₄SiW₁₂O₄₀) at concentrations of up to 1.0 g/L. These coatings were intended for the decomposition of methyl orange (MO) through photocatalysis. The morphology, chemical composition, crystal structure and absorption properties of the coatings were investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, wavelength-dispersive X-ray spectroscopy, X-ray diffraction, photoelectron spectroscopy and diffuse reflectance spectroscopy. Under artificial sunlight, the PA of the coatings was investigated using MO decomposition. The photocatalytic activity (PA) of the ZnO/WO₃ coatings was higher than that of the ZnO obtained in SE. The decrease in the recombination rate of photo-generated electron/hole pairs due to the coupling of ZnO and WO₃ is related to the increased PA. The PA for ZnO and the most photocatalytically active ZnO/WO₃ was around 72% and 96%, respectively, after 8 h of irradiation. A mechanism for MO photo-degradation by the ZnO/WO₃ photocatalyst was also proposed. Full article

Iron phosphate (FePO₄·2H₂O) was synthesized via anodic oxidation using nickel–iron alloy composition simulates from laterite nickel ore as the anode and graphite electrodes as the cathode, with phosphoric acid serving as the electrolyte. A uniform experimental design was employed to systematically optimize the synthesis parameters including voltage, electrolyte concentration, electrolysis time, and degree of acidity or alkalinity (pH). The results indicate that the addition of cetyltrimethylammonium bromide (CTAB) surfactant effectively modulated the morphology of the anodic oxidation products. The optimized conditions were determined to be an electrolyte concentration of 1.2 mol/L, a voltage of 16 V, a pH of 1.6, an electrolysis time of 8 h, and a 3% CTAB addition. Under these conditions, the synthesized FePO₄·2H₂O exhibited enhanced performance as a lithium-ion battery precursor. Specifically, the corresponding LiFePO₄/C cathode delivered an initial discharge capacity of 157 mA h g⁻¹ at 0.2 C, retaining 99.36% capacity after 100 cycles. These findings provide valuable insights and theoretical foundations for the efficient preparation of iron phosphate precursors, highlighting the significant impact of optimized synthesis conditions on the electrochemical performance of lithium iron phosphate. Full article

The galvanostatic electrodeposition of cobalt–nickel alloy coatings performed out on a 304 stainless steel substrate. The electrolyte baths contained metals salts, along with boric acid and sodium benzene sulfonate (SBS) as an organic additive in the deposition process. Structural and topographic analyses were performed using SEM-EDS and AFM techniques, respectively. The findings confirm the formation of nanostructured coatings. The images depicting various stages of coating formation indicated the inhibitory role of the organic additive. The presence of SBS enabled the formation of a coating composed of grains with diverse geometries and significantly reduced surface roughness. Hydrogen evolution was conducted in an alkaline environment (1 M NaOH). Overpotentials for the different structures were recorded at 10 mA/cm², yielding 196 mV and 225 mV for the coatings deposited with and without SBS, respectively. Additionally, experiments were performed in a laboratory-designed electrolyzer, which allowed for the measurement of gas volumes (H₂ and O₂) generated under constant voltage and current conditions. The results demonstrated that the obtained coatings perform more effectively as hydrogen evolution cathodes than currently used materials, particularly under higher current densities. Electrolysis was conducted for 8 h, revealing improved stability of the coating deposited in the presence of SBS. Full article

Marine biofouling causes significant economic losses, and conventional antifouling methods are often associated with environmental pollution. Hydrogen peroxide (H₂O₂), as a clean energy source, has gained increasing attention in recent years. Meanwhile, electrocatalytic 2e⁻ oxygen reduction reaction (ORR) for H₂O₂ production has received growing interest. However, the majority of current studies are conducted on acidic or alkaline electrolytes, and research on 2e⁻ ORR in neutral NaCl solutions remains rare. Here, a bimetallic Zn-Cd zeolitic imidazolate framework (ZnCd-ZIF) is rationally designed to achieve chloride-resistant 2e⁻ ORR catalysis under simulated seawater conditions (pH 7.5, 3.5% Cl⁻). Experimental results demonstrate that the ZnCd-ZIF catalyst exhibits an exceptional H₂O₂ selectivity of 70% at 0.3 V_RHE, surpassing monometallic Zn-ZIF (60%) and Cd-ZIF (50%). Notably, H₂O₂ production reaches 120 mmol g⁻¹ in a Cl⁻-containing neutral electrolyte, exhibiting strong resistance to structural corrosion and Cl⁻ poisoning. This work not only pioneers an effective strategy for designing ORR catalysts adapted to marine environments but also advances the practical implementation of seawater-based electrochemical H₂O₂ synthesis. Full article

Developing low-cost electrocatalysts for efficient hydrogen evolution in both acidic and alkaline conditions is crucial for water-electrolytic hydrogen applications. Herein, MoP was synthesized via a simple, low-cost, and green phosphorization route. More importantly, the Ru/MoP composite prepared using the as-synthesized MoP as a reactant, which exhibited excellent catalytic activity for the hydrogen evolution reaction. It showed lower overpotentials of 108 and 55 mV at 10 mA·cm⁻² in acidic and alkaline solutions, respectively, which are superior to those of bare Ru and pristine MoP as well as comparable or even better than those of previously reported excellent Ru- or MoP-based catalysts. In addition, it also demonstrated small Tafel slopes of 52.6 mV dec⁻¹ and 67.9 mV dec⁻¹ in acidic and alkaline solutions, respectively, along with long-term stability. This work provides an effective and feasible route to design high-efficient MoP-based electrocatalysts for hydrogen evolution reaction. Full article

Enlarging the M-Nx active-site density is an effective route to enhance the ORR performance of M-N-C catalysts. In this work, a single-atom catalyst Cu–N@Cu–N–C with enlarged Cu–N₄ active site density was prepared by the second doping and pyrolysis (SDP) of Cu–N–C derived from Cu-doped zeolite imidazole frameworks. The half-wave potentials of Cu–N@Cu–N–C were measured as 0.85 V in alkaline electrolyte and 0.75 V in acidic media, which was 50 mV and 60 mV higher than that of Cu–N–C, respectively. N₂ adsorption–desorption isotherm curves and corresponding pore distribution analysis were used to verify the successful filling of additional Cu and N in micropores of Cu–N–C after SDP. The obvious increase in Cu contents for Cu–N@Cu–N–C (1.92 wt%) compared with Cu–N–C (0.88 wt%) tested by ICP demonstrated the successful doping of Cu into Cu–N–C. XAFS analysis confirmed the presence of Cu–N₄ single-atom active centers in Cu–N@Cu–N–C. The N 1 s high-resolution XPS results proved a great increase in Cu–N₄ contents from 13.15% for Cu–N–C to 18.36% for Cu–N@Cu–N–C. The enhanced ORR performance of Cu–N@Cu–N–C was attributed to the enlargement of Cu–N₄ active site density, providing an effective route for the preparation of efficient and low-cost ORR catalysts. Full article

An investigation has been carried out to understand the solution chemistry of the Cu-NH⁻-SO₄⁻² system, focusing on the effect of pH on the solubility of copper in the solution and maximizing the Cu(I):Cu(II) ratio. A Pourbaix diagram for the Cu-N-S system has also been created using the HSC Chemistry software for a wide range of Cu-NH₃ species, unlike most other studies that focused only on Cu(NH₃)₄²⁺ and Cu(NH₃)₅²⁺ (Cu(II)) as the dominant species. The Pourbaix diagram demonstrated that the Cu(I) exists as Cu(NH₃)₂⁺, while the Cu(II) species are present in the system as Cu(NH₃)₄²⁺ and Cu(NH₃)₅²⁺, depending upon the Eh and pH of the solution. Copper precipitation was observed in the electrolyte at pH values less than 8.0, and the precipitation behavior increased as the pH became acidic. The highest Cu(I):Cu(II) ratio was observed at higher pH values of 10.05 due to the higher solubility of copper at higher alkaline pH. The maximum Cu(II) concentration can be achieved at 4.0 M NH₄OH and 0.76 M (NH₄)₂SO₄. In the case of low pH, the highest Cu(I):Cu(II) ratio obtained was 0.91 against the 4.0 M and 0.25 M concentrations of NH₄OH and (NH₄)₂SO₄, respectively. Meanwhile, at high pH, the maximum Cu(I):Cu(II) ratio was 15.11 against the 0.25 M (NH₄)₂SO₄ and 4.0 M NH₄OH. Furthermore, the low pH experiments showed the equilibrium constant (K) K < 1, and the high pH experiments demonstrated K > 1, which justified the lower and higher copper concentrations in the solution, respectively. Full article

Despite considerable progress, high-performing durable catalysts operating under large current densities (i.e., >1000 mA/cm²) are still lacking. To discover platinum group metal-free (PGM-free) electrocatalysts for sustainable energy, our research involves investigating layered topological magnetic materials (semiconducting ferromagnets) as highly efficient electrocatalysts for the hydrogen evolution reaction under high current densities and establishes the novel relations between structure and electrochemical property mechanisms. The materials of interest include transition metal trihalides, i.e., CrCl₃, VCl₃, and VI₃, wherein a structural unit, the layered structure, is formed by Cr (or V) atoms sandwiched between two halides (Cl or I), forming a tri-layer. A few layers of quantum crystals were exfoliated (~50−60 nm), encapsulated with graphene, and electrocatalytic HER tests were conducted in acid (0.5M H₂SO₄) and alkaline (1M KOH) electrolytes. We find a reasonable HER activity evolved requiring overpotentials in a range of 30–50 mV under 10 mA cm⁻² and 400−510 mV (0.5M H₂SO₄) and 280−500 mV (1M KOH) under −1000 mA cm⁻². Likewise, the Tafel slopes range from 27 to 36 mV dec⁻¹ (Volmer–Tafel) and 110 to 190 mV dec⁻¹ (Volmer–Herovsky), implying that these mechanisms work at low and high current densities, respectively. Weak interlayer coupling, spontaneous surface oxidation, the presence of a semi-oxide subsurface (e.g., O–CrCl₃), intrinsic Cl (or I) vacancy defects giving rise to in-gap states, electron redistribution (orbital hybridization) affecting the covalency, and sufficiently conductive support interaction lowering the charge transfer resistance endow the optimized adsorption/desorption strength of H^* on active sites and favorable electrocatalytic properties. Such behavior is expedited for bi-/tri-layers while exemplifying the critical role of quantum nature electrocatalysts with defect sites for industrial-relevant conditions. Full article

The development of photoelectrochemical tandem cells for water splitting with electrodes entirely based on metal oxides is hindered by the scarcity of stable p-type oxides and the poor stability of oxides in strongly alkaline and, particularly, strongly acidic electrolytes. As a novelty in the context of transition metal oxide photoelectrochemistry, a bias-free tandem cell driven by simulated sunlight and based on a CuCrO₂ photocathode and a WO₃ photoanode, both unprotected and free of co-catalysts, is demonstrated to split water while working with strongly acidic electrolytes. Importantly, the Faradaic efficiency for H₂ evolution for the CuCrO₂ electrode is found to be about 90%, among the highest for oxide photoelectrodes in the absence of co-catalysts. The tandem cell shows no apparent degradation in short-to-medium-term experiments. The prospects of using a practical cell based on this configuration are discussed, with an emphasis on the importance of modifying the materials for enhancing light absorption. Full article

Securing ever-increasing energy demands while reducing resilience on fossil fuels is a major task of modern society. Fuel cells are devices in which the chemical energy of various fuels can be converted into clean electricity. Direct ethanol fuel cells (DEFC) are increasingly popular for their eco-friendliness and significantly easier liquid fuel manipulation compared to hydrogen-fed fuel cells. Carbon-supported Pt nanoparticles are considered reference catalysts for fuel oxidation in DEFCs. Several challenges hinder DEFC commercialization: high Pt-loading, Pt poisoning by CO intermediates, and the instability of the Pt and carbon supports. This work demonstrates an efficient electrocatalyst for ethanol oxidation reaction (EOR) composed of Pt nanoparticles supported on electrochemically exfoliated graphene (Pt/el-rGO). Graphene was obtained through anodic electrochemical exfoliation using graphitic tape as the anode, while Pt nanoparticles were synthesized using chemical reduction with formic acid. As-obtained Pt/el-rGO with only 7.5 wt.% Pt was characterized using TEM, SEM, and XPS. Pt/el-rGO exhibited notably higher EOR catalytic activity in an alkaline electrolyte than the Pt/C benchmark. This enhancement can be linked with the functional groups present on the graphene support, which facilitate ethanol dehydrogenation as the first step in the EOR mechanism and thus enhance reaction kinetics on Pt-active sites. Full article

The objectives of this study were (i) to determine pH and electrolyte concentrations in MGS collected prepartum and at parturition, (ii) to characterize mare milk pH during the first week postpartum, and (iii) to evaluate pre-foaling MGS pH at three storage temperatures. This study outlined two hypotheses: (i) all mares exhibit acidic pH, increased calcium, magnesium, and potassium, and reduced sodium concentrations regardless of prepartum pH and electrolytes; (ii) pre-foaling MGS pH varies with storage temperature and time in an initial value-dependent manner. Twenty-three multiparous mares were monitored daily from 320 days of gestation until parturition. Pre-foaling MGS was collected, and pH was immediately measured using a hand-held pH meter. Aliquots were preserved for further electrolyte analysis. Postpartum, samples from day −7 to 0 (day of foaling) were thawed, and electrolyte concentrations (calcium, magnesium, sodium, potassium) were determined. For the three storage temperatures, pH was measured at 0, 15, 30, 45, and 60 min after storage, and hourly for 10 h post-collection. A range of pH 8 to 6.5 was included to avoid bias towards a specific pH value. The chosen pH groups were 8 (range 7.8–8.2), 7.5 (range 7.3–7.7), 7 (6.7–7.2), and 6.5 (6.2–6.6). Overall, storage temperature affects pH (p < 0.05). In conclusion, this study demonstrated that the majority of the mares had sodium–potassium inversion and acidic pH at foaling. Milk pH is neutral up to four days after foaling, becoming slightly alkaline afterwards, with undetermined clinical significance. The pH of MGS showed minimal variation across storage temperatures, except for pH ~7.5, which increased to ~8 post-storage. This study is the first to address these physiological and practical questions about MGS pH in periparturient mares. Full article

Although an enzymatic electrochemical biosensor is a major keystone in Diabetes Mellitus management, its replacement with a low-cost and stable non-enzymatic glucose sensor (NEGS) is of high interest to scientific and industrial fields. However, most NEGS for direct glucose electrooxidation (DGE) must be performed under extreme alkaline conditions, implying additional pretreatments before detection and a limited application for on-body, real-time monitoring. Thus, research on DGE in physiological conditions is fundamental to successfully translating the current NEGS into clinical applications. In physiological conditions, drawbacks such as low current, low selectivity, and poisoning appear due to the reduction of OH ions in neutral electrolytes and the presence of chloride ions in biofluids. Therefore, an increasing number of nanomaterials based on Pt, Au, and their nanocomposites have been proposed to improve the electrochemical performance. Additionally, transition metals such as Cu, Pd, Ni, or Co combined with high surface area supports have shown promising results in increasing catalytic sites for DGE. The molecular interaction of phenylboronic acid with glucose has also been demonstrated in neutral conditions. Overall, the present review summarizes the current strategies for DGE in physiological conditions and highlights the challenges still faced for further development of functional glucose NEGS. Full article

Electrocatalytic alcohol oxidation (EAO) is an attractive alternative to the sluggish oxygen evolution reaction in electrochemical hydrogen evolution cells. However, the development of high-performance bifunctional electrocatalysts is a major challenge. Herein, we developed a nitrogen-doped bimetallic oxide electrocatalyst (WO-N/NF) by a one-step hydrothermal method for the selective electrooxidation of benzyl alcohol to benzoic acid in alkaline electrolytes. The WO-N/NF electrode features block-shaped particles on a rough, inhomogeneous surface with cracks and lumpy nodules, increasing active sites and enhancing electrolyte diffusion. The electrode demonstrates exceptional activity, stability, and selectivity, achieving efficient benzoic acid production while reducing the electrolysis voltage. A low onset potential of 1.38 V (vs. RHE) is achieved to reach a current density of 100 mA cm⁻² in 1.0 M KOH electrolyte with only 0.2 mmol of metal precursors, which is 396 mV lower than that of water oxidation. The analysis reveals a yield, conversion, and selectivity of 98.41%, 99.66%, and 99.74%, respectively, with a Faradaic efficiency of 98.77%. This work provides insight into the rational design of a highly active and selective catalyst for electrocatalytic alcohol oxidation. Full article

This review examines the impact of various aqueous electrolytes on hydrogen absorption and self-corrosion in magnesium (Mg) anodes. The discussion integrates both historical and recent studies to explore the mechanisms behind self-corrosion and anomalous hydrogen evolution (HE) under conditions of the Negative Difference Effect (NDE) and Positive Difference Effect (PDE). The focus is on the formation and oxidation of magnesium hydride in regions of active dissolution under NDE conditions. In the case of PDE, anodic dissolution occurs through the passive MgO-Mg(OH)₂ film, which shields the metal from aqueous electrolytes, thereby reducing hydrogen absorption and abnormal HE. The NDE conditions showed delayed reduction activity at the surface, attributed to a hydride phase within the corrosion product layer. Hydride ions were quantified through their anodic oxidation in an alkaline electrolyte, measured by the electric charge passed. The review also considers the role of de-passivating halide ions, electrolyte acidity buffering, and the addition of ligands that form stable complexes with Mg²⁺ ions, on the rates of hydride formation, self-corrosion, and anodic dissolution of Mg. The study evaluates species that either inhibit or promote hydrogen absorption and self-corrosion. Full article