Minimal doping approach to activate lattice oxygen participation in K2WO4 electrocatalysts for oxygen evolution reaction

Abstract

Understanding oxygen redox processes is pivotal for advancing oxygen evolution catalysts, critical in electrochemical devices for renewable fuel synthesis. Thermodynamic instability of high entropy metal oxides can interfere with oxygen redox reactions via electrochemical reconstruction. Transforming a WN pre-catalyst into thermodynamically stable KWO through electrochemical treatment in KOH, and incorporating minimal Fe doping, modifies the oxygen evolution reaction (OER) pathway towards oxygen redox activity, significantly influenced by the pH of the electrolyte. The Fe-doped KWO catalyst demonstrates superior OER performance, achieving 10 mA/cm^2 at an overpotential of merely 181 mV (without iR compensation) and sustaining a lifetime of 1200 h at 1000 mA/cm. Electrochemical methods and DFT calculations confirmed Fe doping creates oxygen vacancies and increases electron density near the Fermi level, enhancing the OER pathway. This methodology offers a versatile approach to adapt high entropy catalysts for broad electrochemical energy conversion applications, highlighting its potential for innovation in renewable energy technologies.