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[Display omitted] The adsorption energy of oxygen-containing intermediates for the oxygen evolution reaction (OER) electrocatalysts plays a key role on their electrocatalytic performances. Rational optimization and regulation of the binding energy of intermediates can effectively improve the catalytic activities. Herein, the binding strength of Co phosphate to *OH was weakened by generating lattice tensile strain via Mn replacement, which modulated the electronic structure and optimized the reactive intermediates adsorption with active sites. The tensile-strained lattice structure and stretched interatomic distance were confirmed by X-ray diffraction and extended X-ray absorption fine structure (EXAFS) spectra measurements. The as-obtained Mn-doped Co phosphate exhibits excellent OER activity with an overpotential of 335 mV at 10 mA cm−2, which is much higher than pristine Co phosphate. In-situ Raman spectra and methanol oxidation reaction experiments demonstrated that Mn-doped Co phosphate with lattice tensile strain shows optimized *OH adsorption strength, and is favorable to structure reconstruction and form highly active Co oxyhydroxide intermediate during OER process. Our work provides insight into the effects of the lattice strain on the OER activity from the standpoint of intermediate adsorption and structure transformation. [ABSTRACT FROM AUTHOR]

Herein, the relationship between vacancy concentration and electrocatalytic water splitting performance has been investigated. The CoS1.25Se0.75@NC possesses the largest vacancy concentration as well as the optimal electrocatalytic performance. [Display omitted] Anion substitution is a valid strategy to modulate the active sites of the transition metal dichalcogenides (TMDs). Herein, a series of cobalt sulfoselenide nanomeshes (CoS 2(1-x) Se 2x @NC) were synthesized by calcining S/Se power with ultrathin metal–organic framework (MOFs) nanosheets. The vacancy concentration of CoS 2(1-x) Se 2x @NC could be adjusted through changing the ratio of S/Se precursor. Interestingly, CoS1.25Se0.75@NC electrocatalyst possesses the largest vacancy concentration as well as the optimal electrocatalytic performance. CoS 1.25 Se 0.75 @NC delivers an overpotential as low as 134 mV for hydrogen evolution reaction (HER) and 270 mV for oxygen evolution reaction (OER) at the current density of 10 mA cm -2, respectively. Furthermore, CoS 1.25 Se 0.75 @NC affords a low cell voltage of 1.67 V (at 10 mA cm−2) and outstanding cycling stability for overall water splitting reaction (more than 55 h). For HER process, theoretical calculations prove that anion vacancy not only lower the free energy barrier of H 2 O dissociation step but also favor the desorption step of intermediate H*. For OER process, the anion vacancies could modulate the adsorption/desorption free energy of oxygen-containing intermediates. The present work demonstrates a practical approach to modulate the vacancy concentration of cobalt sulfoselenide and provides new ideas for design of efficient non-metal electrocatalysts. [ABSTRACT FROM AUTHOR]

The addition of CrO 4 2− can create a stable anion environment around the catalyst electrode to promote the formation and stabilization of the metal oxyhydroxide active phase and repel Cl− away from the catalyst surface, which would mitigate the adverse effect of Cl− on the anode. [Display omitted] • CrO 4 2− generally promotes the OER activity of Ni-based LDHs in alkaline seawater. • The addition of CrO 4 2− boosts the formation of the metal oxyhydroxide active phase. • The additive CrO 4 2− greatly enhances the Cl−-corrosion resistance of NiFe-LDH. Seawater electrolysis to generate hydrogen offers a clean, green, and sustainable solution for new energy. However, the catalytic activity and durability of anodic catalysts are plagued by the corrosion and competitive oxidation reactions of chloride in high concentrations. In this study, we find that the additive CrO 4 2− anions in the electrolyte can not only promote the formation and stabilization of the metal oxyhydroxide active phase but also greatly mitigate the adverse effect of Cl− on the anode. Linear sweep voltammetry, accelerated corrosion experiments, corrosion polarization curves, and charge transfer resistance results indicate that the addition of CrO 4 2− distinctly improves oxygen evolution reaction (OER) kinetics and corrosion resistance in alkaline seawater electrolytes. Especially, the introduction of CrO 4 2− even in the highly concentrated NaCl (2.5 M) electrolyte prolongs the durability of NiFe-LDH to almost five times the case without CrO 4 2−. Density functional theory calculations also reveal that the adsorption of CrO 4 2− can tune the electronic configuration of active sites of metal oxyhydroxides, enhance conductivity, and optimize the intermediate adsorption energies. This anionic additive strategy can give a better enlightenment for the development of efficient and stable oxygen evolution reactions for seawater electrolysis. [ABSTRACT FROM AUTHOR]