Discharge Induced-Activation of Phosphorus-Doped Nickel Oxyhydroxide for Oxygen Evolution Reaction

Heteroatom dopants often show strong regulation ability towards electronic structure on the surface of electrocatalysts and result in surprising electrochemical activity for oxygen evolution reaction (OER). Despite many efforts, the fundamental understanding concerning the correlations of structure variation and OER conditions is crucial for the identification of active site, yet remains to be explored. Here we report the electrochemical activity of phosphorus doped nickel oxyhydroxide is intrinsically determined by the low applied potential during OER. Based on electrochemical measurements, density functional theory calculations, and mechanism simulation, the descriptor for the relationship of surface structure and electrochemical behavior is established. We uncover that the discharge process will occur at low applied potential region and enable the formation of phosphorous and oxygen vacancies. These in-situ constructed vacancies can optimize the configuration of surface electron for intermediate adsorption and thus facilitate the reaction kinetics. Simultaneously, the discharge process leads to faster mass transfer and thus produces more active sites. As the results, the discharge leads to increase in current density as large as 33.7%. Our work demonstrates the important of discharge process for surface reconstruction and electrochemical performance improvement.