Self-supported CoMoO4/NiFe-LDH core-shell nanorods grown on nickel foam for enhanced electrocatalysis of oxygen evolution.

Abstract

Developing high-performance catalysts is an effective strategy for speeding up the oxygen evolution reaction (OER) and increasing production efficiency. Here, a core-shell electrocatalyst consisting of CoMoO4 nanorods grown in situ on nickel foam substrate covered by nickel-iron layered double hydroxide (NiFe-LDH) via electrodeposition was demonstrated (CoMoO4/NiFe-LDH@NF). Experimental investigations revealed that self-supporting and binder-free electrodes ensured that the catalysts exposed an abundance of active sites, faster electron transfer, and excellent long-cycle stability. The NiFe-LDH shell with a crystalline-amorphous dual structure served as an accurate active material, lowering the energy barrier and contributing more catalytic sites for water oxidation. Furthermore, the core CoMoO4 nanorods not only effectively avoided the accumulation of NiFe-LDH to increase the electrochemically active area but also acted as a highway for electrons from the active site to the substrate to promote the OER kinetics. Specifically, CoMoO4/NiFe-LDH@NF exhibited lower overpotential (180 mV at 10 mA cm-2) and smaller Tafel slope (34 mV dec-1) than pure CoMoO4@NF and NiFe-LDH@NF, revealing its excellent catalytic performance and fast intrinsic reaction kinetics. In addition, CoMoO4/NiFe-LDH@NF exhibited long-term stability of more than 20 h at 50 mA cm-2, further demonstrating its potential for practical applications. These findings pointed to a potential option for building innovative OER catalysts.