A controllable cobalt-doping improve electrocatalytic activity of ZnO basal plane for oxygen evolution reaction: A first-principles calculation study

Abstract

To design highly efficient, low-cost, and good stable electrocatalysts for the oxygen evolution reaction (OER) which is the key to the water-splitting, we doped ZnO with different concentrations of Co based on density functional theory calculations. The precise Co concentrations control from 0 % to 100 % can be achieved by cation exchange reaction in the experiment. The introduction of Co can modulate the electronic structure of ZnO, as the concentration of Co increases, the band gap greatly decreases, the system tunes from the semiconductor to the metal, and the electric conductivity is significantly improved, favoring the OER. The introduction of Co induces charge arrangement, the electrons gradually concentrate on the active site, and the bindings between the oxygen-containing intermediate and the surface are greatly improved, therefore, the potential of the OER decreases, the rate-determining step changes from the first step in pure ZnO to the third step in Co exchanged ZnO. Additionally, Co0.5Zn0.5O exhibits the favorite OER activity with the overpotential of 0.4 V. These interesting findings may simulate experimental validations and facilitate the development of more efficient OER catalysts.