Atomic Doping and Anion Reconstructed CoF2 Electrocatalyst for Oxygen Evolution Reaction

Abstract Electrocatalytic water splitting is one of the most promising green solutions for large‐scale hydrogen production, which has developed rapidly in recent years. The slow reaction rate of oxygen evolution reaction (OER) has become the bottleneck to improve the electrocatalytic efficiency. Herein, Fe‐doped CoF2 nanowire arrays on 3D nickel foam are prepared by two steps of hydrothermal reaction and fluorination process. The increased catalytic activity sites and accelerated charge transfer rate make the self‐supported Fe‐doped CoF2 electrode show excellent OER performance in alkaline electrolyte. An overpotential of 230 mV is only required to release a current density of 10 mA cm−2. The Tafel slope derived from the polarization curves is 59 mV dec−1, indicating outstanding electrochemical kinetics performance. A stable output current density of 84 mA cm−2 for more than 96 h is achieved under an invariant overpotential of 338 mV, attributing to the anion reconstruction making part of CoF2 transform into cobalt hydroxide and further improving its electrocatalytic performance.