Efficient Electrochemical Water Splitting Through Self‐Supported Copper Selenide Nanosheets on Cu Foil: Effect of Immersion Time

Transition metal selenides have been attracting enormous attention for electrocatalytic water oxidation. Herein, a self‐supported Cu 3 Se 2 @Cu electrocatalyst is prepared using the simple self‐growth method at different immersion times. The immersion time is critical in the conversion of Cu(OH) 2 to Cu 3 Se 2 as well as the modification of surface morphology. The growth of thin films is analyzed using a field emission scanning electron microscope and X‐ray photoelectron spectroscopy techniques. The electrochemical analysis shows that 230 and 351 mV of overpotential are required to reach a current density of 10 and 100 mA cm −2 , respectively, for the oxygen evolution reaction (OER). The chronopotentiometry measurement over 50 h at a current density of 100 mA cm −2 shows excellent stability of the self‐grown electrocatalyst. This work may provide an effective and controlled strategy to convert Cu substrate to Cu 3 Se 2 for efficient OER catalysts with the self‐growth method.