Synthetic CuS _<i>x</i> O _{1– <i>x</i>} Copper Oxysulfides Nanosheets by Redox Reaction for Efficient Oxygen Evolution Reaction

Copper-based electrocatalysts are regarded as highly efficient electrocatalysts due to their low cost and environmental friendliness. However, their practical application in water splitting remains severely limited by intrinsic drawbacks such as inferior electron transfer kinetics and moderate catalytic activity. Herein, we synthesized copper oxysulfide (CuSxO1–x) flake-like nanoflowers through a redox reaction and explored their application as efficient electrocatalysts for the oxygen evolution reaction. As expected, compared to the original CuS, the copper oxysulfides exhibited superior OER activity and stability, showing a remarkably low overpotential of 206 mV at a benchmark current density of 10 mA cm–2 for the OER. This study elucidates the reconstruction of copper oxysulfide electrocatalysts during the oxygen evolution reaction through in situ ATR-IR measurements. The facilitated formation of reaction intermediates and accelerated reconstruction kinetics during the structural evolution of copper oxysulfide synergistically contribute to its enhanced oxygen evolution reaction performance.