Controlling the Valence-Electron Arrangement of Nickel Active Centers for Efficient Hydrogen Oxidation Electrocatalysis.

The valence-electron arrangement of heterogeneous catalysts can significantly affect the binding behavior of absorbates. However, it remains a challenge to understand the role of the valence-electron arrangement in electrocatalysis, which limits its utilization as a tool to design efficient electrocatalysts. Here, we describe experiments in which the valence-electron arrangement of Ni active centers for hydrogen oxidation is controlled precisely by using Ni-vacancy-enriched Ni N as a platform. These Ni vacancies can promote the valence-electron delocalization of OH-adsorption centers to enhance the Ni ds-O 2p valence-electron-orbital interaction with elevated OH adsorption. Meanwhile, the deficit of valence-electrons of H-adsorption centers at Ni vacancies can lower Ni ds-H 1s interaction with weakened H binding. Relative to Ni N poor in vacancies, the Ni-vacancy-enriched Ni N showed a mass activity enhanced by 15-fold. This strategy paves a rational way to design efficient catalysts by finely tuning the valence-electron arrangement.