S‐Doping Triggers Redox Reactivities of Both Iron and Lattice Oxygen in FeOOH for Low‐Cost and High‐Performance Water Oxidation

Abstract Developing low‐cost and highly efficient earth‐abundant oxygen evolution reaction (OER) electrocatalysts via an energy‐ and time‐saving method is of great significance to the generation of H 2 from electrochemical water splitting, which is highly desirable but still challenging. Herein, a one‐step route to in situ grow S‐doped FeOOH vertical nanosheets on iron foam (IF) in 20 min under room temperature is shown. This facile and ultrafast method effectively modifies the surface of the IF into an S‐doped FeOOH layer, and a full‐Fe electrode (S‐FeOOH/IF) is achieved. Systematic experiments and characterizations demonstrate that the redox reactivities for both of the iron and lattice oxygen in FeOOH are sufficiently activated, leading to the dramatically improved intrinsic OER activity. The as‐obtained S‐FeOOH/IF exhibits a fascinating OER performance with a low overpotential of 244 at 10 mA cm −2 . This work affords an efficient surface engineering strategy to drive commercial IF into cost‐efficient and robust earth‐abundant electrocatalysts for water oxidation, which has important implications for clean H 2 production through a low‐carbon and environmentally friendly route.