Controllable synthesis of hollow NiSe₂ spheres as an active electrocatalyst for hydrogen evolution reaction

The design of electrocatalysts with excellent performance and low cost is of great significance for the electrocatalytic water splitting. NiSe₂ has been widely concerned because of its suitable adsorption energy and adjustable electronic structure for hydrogen evolution reaction (HER). Here, a hollow spherical NiSe₂ catalyst was designed and prepared by the hydrothermal method. Thanks to the unique three-dimensional (3D) open configuration and favorable active components, it exhibits superior catalytic activity for HER. It delivers an overpotential of 330[Formula: see text]mV at the current density of 10[Formula: see text]mA[Formula: see text]cm[Formula: see text], corresponding to the Tafel slope of 128[Formula: see text]mV[Formula: see text]dec[Formula: see text]. This work demonstrates that the 3D hollow structure with large specific surface and rich internal space can effectively improve the mass transfer efficiency and electron transfer. This work may provide a controllable way for the design of hollow structure catalysts.