Inlaying Ultrathin Bimetallic MOF Nanosheets into 3D Ordered Macroporous Hydroxide for Superior Electrocatalytic Oxygen Evolution.

Abstract

Controllable synthesis of ultrathin metal-organic framework (MOF) nanosheets and rational design of their nano/microstructures in favor of electrochemical catalysis is critical for their renewable energy applications. Herein, an in situ growth method is proposed to prepare the ultrathin NiFe MOF nanosheets with a thickness of 1.5 nm, which are vertically inlaid into a 3D ordered macroporous structure of NiFe hydroxide. The well-designed composite delivers an efficient electrocatalytic performance with a low overpotential of 270 mV at a current density of 10 mA cm-2 and stable electrolysis as long as 10 h toward the electrochemical oxygen evolution reaction, much superior to the state-of-the-art RuO2 electrocatalyst. A comprehensive analysis demonstrates that the excellent performance originates from the desirable combination of the highly exposed active centers in the ultrathin bimetallic MOF nanosheets, effective electron conduction between MOF nanosheets and ordered macroporous hydroxide, and efficient mass transfer across the hierarchically porous hybridization. This study sheds light on the exploration of powerful protocols to gain diverse high-performance MOF nanosheets and may open a perspective to achieve their efficient electrocatalytic performance.