A hierarchical CoMoO@CoFe-LDH heterostructure as a highly effective catalyst to boost electrocatalytic water oxidation.

The oxygen evolution reaction (OER) has become the main barrier to electrochemical water splitting, owing to sluggish kinetics. To accelerate the OER process, a nature-abundant non-noble metal catalyst with outstanding catalytic activity is required. Here, a hierarchical CoMoO@CoFe layered double hydroxide (LDH, denoted by CoMoO@CoFe/NF) heterostructure supported on three-dimensional (3D) nickel foam (NF) was synthesised by electrodepositing CoFe-LDH nanosheets on the surface of CoMoO nanoplates to boost the electrocatalytic performance for the OER. The coupling between CoMoO and CoFe-LDH established abundant boundaries, which exposed abundant active sites. Furthermore, the electron transfer in the hierarchical heterostructure effectively promoted the adsorption and dissociation of HO molecules. Harnessing the aforementioned synergistic effect significantly improved the intrinsic reaction kinetics of the OER. At 10 mA cm, CoMoO@CoFe/NF reached a small overpotential of 245 mV at room temperature and exhibited outstanding stability for at least 47 h. Furthermore, the Tafel slope for CoMoO@CoFe/NF was only 46 mV dec. This study provides new ideas for the rational design of hierarchical structures and the use of interface interactions.