Heterophase junction engineering-induced Co spin-state modulation of CoSe_(2) for large-current hydrogen evolution reaction

Efficient electrocatalysts are vital to large-current hydrogen production in commercial water splitting for green energy generation.Herein,a novel heterophase engineering strategy is described to produce polymorphic CoSe_(2)electrocatalysts.The composition of the electrocatalysts consisting of both cubic CoSe_(2)(c-CoSe_(2))and orthorhombic CoSe_(2)(o-CoSe_(2))phases can be controlled precisely.Our results demonstrate that junction-induced spin-state modulation of Co atoms enhances the adsorption of intermediates and accelerates charge transfer resulting in superior large-current hydrogen evolution reaction(HER)properties.Specifically,the CoSe_(2)based heterophase catalyst with the optimal c-CoSe_(2)content requires an overpotential of merely 240 mV to achieve 1,000 mA·cm^(-2)as well as a Tafel slope of 50.4 mV·dec^(-1).Furthermore,the electrocatalyst can maintain a large current density of 1,500 mA·cm^(-2)for over 320 h without decay.The results reveal the advantages and potential of heterophase junction engineering pertaining to design and fabrication of low-cost transition metal catalysts for large-current water splitting.

Fullerene-derived boron-doped defective nanocarbon for highly selective H_(2)O_(2) electrosynthesis

Electrochemical production of hydrogen peroxide(H_(2)O_(2))via the two-electron(2e-)pathway of oxygen reduction reaction(ORR)supplies an auspicious alternative to the current industrial anthraquinone process.Nonetheless,it still lacks efficient electrocatalysts to achieve high ORR activity together with 2e-selectivity simultaneously.Herein,a boron-doped defective nanocarbon(B-DC)electrocatalyst is synthesized by using fullerene frameworks as the precursor and boric oxide as the boron source.The obtained B-DC materials have a hierarchical porous structure,befitting boron dopants,and abundant topological pentagon defects,exhibiting a high ORR onset potential of 0.78 V and a dominated 2e-selectivity(over 95%).Remarkably,when B-DC electrocatalyst is employed in a real device,it achieves a high H_(2)O_(2) yield rate(247 mg·L^(-1)·h^(-1)),quantitative Faraday efficiency(~100%),and ultrafast organic pollutant degradation rate.The theoretical calculation reveals that the synergistic effect of topological pentagon defects and the incorporation of boron dopants promote the activation of the O_(2) molecule and facilitates the desorption of oxygen intermediate.This finding will be very helpful for the comprehension of the synergistic effect of topological defects and heteroatom dopants for boosting the electrocatalytic performance of nanocarbon toward H_(2)O_(2) production.