Coupled vacancy pairs in Ni‐doped CoSe for improved electrocatalytic hydrogen production through topochemically deintercalation

Vacancy engineering plays vital role in the design of high-performance electrocatalyst. Here, we introduced coupled cation vacancy pairs in Ni-doped CoSe to achieve boosted HER activity, through a facile topochemical intercalation approach. Adjacent Co vacancy pairs and heteroatom Ni doping contribute together for the upshift of the Se 4 p z orbital, which induces larger overlap between the Se 4p and H 1s electron clouds. As a result, the free energy of H adsorption can be reduced largely. 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.