Secondary Transition-Metal Dopants for Enhanced Electrochemical O₂ Formation and Desorption on Fe-Doped β-NiOOH

Previously we outlined possible doping strategies to improve the aqueous electrocatalytic oxygen evolving activity of iron-doped nickel oxyhydroxide (Ni_1-xFe_xOOH). The strategies are based on two central mechanistic features of its efficient water oxidation: (1) metal-oxo bond formation and (2) three-electron reductive elimination of O₂. Here, we explore secondary dopants that may promote the latter by enhancing O-O bond formation. From periodic slab models using screened-exchange hybrid density functional theory, we predict that Fe³⁺-doped β-NiOOH codoped with Cu²⁺ or Ag³⁺ will have even more favorable O-O coupling and molecular O₂ desorption activity at the Fe sites. This work illustrates a mechanism-oriented design principle in the development of oxygen evolution catalysts.