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Abstract Anion-tuning in metallic chalcogenides has been shown to have a significant impact on their electrocatalytic ability for overall water splitting. In this article, copper-based chalcogenides (Cu₂X, X= O, S, Se, and Te) have been systematically studied to examine the effect of decreasing anion electronegativity and increasing covalency on the electrocatalytic performance. Among the copper chalcogenides, Cu₂Te has the highest oxygen evolution reaction (OER) activity and can sustain high current density of 10 and 50 mA cm⁻²for 12 h. The difference in intrinsic catalytic activity of these chalcogenide surfaces have been also probed through density functional theory calculations, which was used to estimate energy of the catalyst activation step. It was observed that the hydroxyl adsorption on the surface catalytic site is critically important for the onset and progress of OER activity. Consequently, it was also observed that the –OH adsorption energy can be used as a simple but accurate descriptor to explain the catalytic efficiency through volcano-like correlation plot. Such observation will have a significant impact on developing design principle for optimal catalytic surface exhibiting high performance as well as prolonged stability. 

A mixed-metal ternary chalcogenide, cobalt molybdenum telluride (CMT), has been identified as an efficient tri-functional electrocatalyst for seawater splitting, leading to enhanced oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). The CMT was synthesized by a single step hydrothermal technique. Detailed electrochemical studies of the CMT-modified electrodes showed that CMT has a promising performance for OER in the simulated seawater solutions, exhibiting a small overpotential of 385 mV at 20 mA cm−2, and superior catalyst durability for prolonged period of continuous oxygen evolution. Interestingly, while gas chromatography analysis confirmed the evolution of oxygen in an anodic chamber, it showed that there was no chlorine evolution from these electrodes in alkaline seawater, highlighting the novelty of this catalyst. CMT also displayed remarkable ORR activity in simulated seawater as indicated by its four-electron reduction pathway forming water as the dominant product. One of the primary challenges of seawater splitting is chlorine evolution from the oxidation of dissolved chloride salts. The CMT catalyst successfully and significantly lowers the water oxidation potential, thereby separating the chloride and water oxidation potentials by a larger margin. These results suggest that CMT can function as a highly active tri-functional electrocatalyst with significant stability, making it suitable for clean energy generation and environmental applications using seawater. 

Developing protocols for designing high‐efficiency, durable, cost‐effective electrocatalysts for oxygen evolution reaction (OER) necessitates deeper understanding of structure–property correlation as a function of composition. Herein, it has been demonstrated that incorporating tellurium into binary nickel chalcogenide (NiSe) and creating a mixed anionic phase perturbs its electronic structure and significantly enhances the OER activity. A series of nanostructured nickel chalcogenides comprising a layer‐by‐layer morphology along with mixed anionic ternary phase are grown in situ on nickel foam with varying morphological textures using simple hydrothermal synthesis route. Comprehensive X‐ray diffraction, X‐ray photoelectron spectroscopy, and in situ Raman spectroscopy analysis confirms the formation of a trigonal single‐phase nanocrystalline nickel (telluro)‐selenide (NiSeTe) as a truly mixed anionic composition. The NiSeTe electrocatalyst exhibits excellent OER performance, with a low overpotential of 300 mV at 50 mA cm⁻²and a small Tafel slope of 98 mV dec⁻¹in 1 mKOH electrolyte. The turnover frequency and mass activity are 0.047 s⁻¹and 90.3 Ag⁻¹, respectively. Detailed electrochemical measurements also reveal enhanced charge transfer properties of the NiSeTe phase compared to the mixture of binaries. Density functional theory calculations reveal favorable OH adsorption energy in the mixed anionic phase compared to the binary chalcogenides confirming superior electrocatalytic property. 

Developing simple, affordable, and environmentally friendly water oxidation electrocatalysts with high intrinsic activity and low overpotential continues to be an area of intense research. In this article, a trichromium diselenide carbonyl cluster complex (Et4N)2[Se2Cr3(CO)10], with a unique bonding structure comprising bridging Se groups, has been identified as a promising electrocatalyst for oxygen evolution reaction (OER). This carbonyl cluster exhibits a promising overpotential of 310 mV and a low Tafel slope of 82.0 mV dec−1 at 10 mAcm−2, with superior durability in an alkaline medium, for a prolonged period of continuous oxygen evolution. The mass activity and turnover frequency of 62.2 Ag−1 and 0.0174 s−1 was achieved, respectively at 0.390 V vs. RHE. The Cr-complex reported here shows distinctly different catalytic activity based on subtle changes in the ligand chemistry around the catalytically active Cr site. Such dependence further corroborates the critical influence of ligand coordination on the electron density distribution which further affects the electrochemical activation and catalytic efficiency of the active site. Specifically, even partial substitution with more electronegative substituents leads to the weakening of the catalytic efficiency. This report further demonstrates that metal carbonyl chalcogenides cluster-type materials which exhibit partially occupied sites and high valence in their metal sites can serve as catalytically active centers to catalyze OER exhibiting high intrinsic activity. The insight generated from this report can be directly extrapolated to 3-dimensional solids containing similar structural motifs, thereby aiding in optimal catalyst design.