Sulfur-doping/leaching induced structural transformation toward boosting electrocatalytic water splitting

Rational modulation for the composition and structure of the oxygen evolution reaction (OER) electrocatalysts is crucial for overall water splitting. Herein, how to utilize composition change and structure reconstruction via an in situ nonmetal element-doping and leaching-induced strategy to develop robust water oxidation catalysts is firstly proposed. The as-obtained Ni-FeOOH with structural transformation presents a remarkable OER activity with an overpotential of 224 mV at 100 mA/cm2, which is much superior to undoped or unleached catalysts. By tuning the amount of S, the S-doped NiFe-based catalyst exhibits an overpotential of 168 mV at 100 mA/cm2 for the hydrogen evolution reaction. The electrocatalysts with tunable bifunctionality requires only 1.43 V to drive 10 mA/cm2 towards overall water splitting. Systematic experiments and characterizations demonstrate that structural reconstruction into highly active oxyhydroxides species and sufficient activation of lattice oxygen redox reactivity are responsible for the fascinating OER activity induced by S doping/leaching.