Amorphous Cobalt-Iron Hydroxide Nanosheet Array Electrocatalyst for Efficient Electrochemical and Photoelectrochemical Oxygen Evolution

Abstract

Water splitting by electrolysis or solar-driven photoelectrochemical (PEC) reaction has been broadly recognized as one of the most promising chemical method for sustainable energy conversion and storage systems. However, the overall efficiency of water splitting is largely limited by the kinetically sluggish oxygen evolution reaction (OER). Efficient electrocatalysts are required to enhance OER by lowering the overpotential and accelerating the kinetics. Herein, we report amorphous cobalt-iron hydroxide (CoFe-H) nanosheet array synthesized by a facile electrodeposition method as a highly efficient OER catalyst for both electrochemical and photoelectrochemical water splitting. The nanosheet array maximized the electrochemically active surface area, meanwhile the amorphous features with abundant defects offered rich active sites for OER. Therefore, the amorphous CoFe-H nanosheet array exhibited superior electrochemical activity toward OER. More importantly, we designed CoFe-H/BiVO4 core-shell architecture for PEC-OER system. Due to the high efficient OER activity of amorphous CoFe-H nanosheets, CoFe-H/BiVO4 photoanodes also exhibited superior PEC-OER performance. Our work provides a promising approach to fabricate highly efficient electrocatalysts for electrochemical and solar-driven photoelectrochemical water splitting.