Theoretical and experimental study of the effects of cobalt and nickel doping within IrO2 on the acidic oxygen evolution reaction

Abstract

The effect of Ni and Co doping within IrO2 on the structure and oxygen evolution reaction (OER) was studied using integrated theory and experiments. Density Functional Theory (DFT) calculations show that the metal dopant influences the distribution of electronic charge and affects the thermodynamics and kinetics aspects of the OER when compared with undoped IrO2. Using DFT, multiple different reaction pathways were evaluated for O-O bond formation, and analysis supports the associative mechanism to be the most likely reaction pathway. Calculations showed lower activation energies for Ni and Co-doped IrO2 compared to undoped IrO2, in agreement with experimental analysis of the activation energy and OER activity. From experiments, Co-doping shows significantly improved stability compared to Ni-doping. Evaluation of the rate-determining step (rds) from calculations and experimental analysis shows apparent differences that indicate the additional factors need to be considered to enable improved correlation between theory and experiment regarding the OER rds.