Fe2+-Induced In Situ Intercalation and Cation Exsolution of Co80Fe20(OH)(OCH3) with Rich Vacancies for Boosting Oxygen Evolution Reaction

The efficiency of water splitting is largely hindered by the sluggish kinetics of the oxygen evolution reaction. Cobalt-based (oxy)hydroxides are promising electrocatalysts, but their performance is still under the expected goal due to the restricted active sites and intrinsic activity. Herein, Co80Fe20(OH)(OCH3) (CoFeMe) is synthesized with intercalation and rich vacancies by a cation exsolution process in a one-step solve-thermal reaction. With the help of the Fe incorporation, the specific surface area of CoFeMe increases to 101.6 m(2) g(-1), which is six times that of Co(OH)(OCH3) (CoMe) (16.5 m(2) g(-1)). Also, the induced rich vacancies are traced in the X-ray absorption spectra of CoFeMe. Because of the synergistic effect between the intercalation, Fe incorporation and vacancies, the overpotential of CoFeMe is only 240 mV to drive the current density to 10 mA cm(-2), which is reduced 110 mV compared with that of pristine CoMe (350 mV).