Coupled Vacancy Pairs in Ni‐Doped CoSe for Improved Electrocatalytic Hydrogen Production Through Topochemical Deintercalation

Vacancy engineering plays vital role in the design of high-performance electrocatalysts. Here, we introduced coupled cation-vacancy pairs in Ni-doped CoSe to achieve boosted hydrogen evolution reaction (HER) activity through a facile topochemical intercalation approach. Adjacent Co vacancy pairs and heteroatom Ni doping contribute together for the upshift of the Se 4p_z orbital, which induces larger overlap between the Se 4p and H 1s orbitals. As a result, the free energy of H adsorption can be lowered significantly. With an advanced HER activity of 185.7 mV at 10 mA cm^-2 , this work provides new direction and guidance for the design of novel electrocatalysts.