A hierarchical CoMoO₄@CoFe-LDH heterostructure as a highly effective catalyst to boost electrocatalytic water...

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 CoMoO₄@CoFe layered double hydroxide (LDH, denoted by CoMoO₄@CoFe/NF) heterostructure supported on three-dimensional (3D) nickel foam (NF) was synthesised by electrodepositing CoFe-LDH nanosheets on the surface of CoMoO₄ nanoplates to boost the electrocatalytic performance for the OER. The coupling between CoMoO₄ 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 H₂O molecules. Harnessing the aforementioned synergistic effect significantly improved the intrinsic reaction kinetics of the OER. At 10 mA cm^-2, CoMoO₄@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 CoMoO₄@CoFe/NF was only 46 mV dec^-1. This study provides new ideas for the rational design of hierarchical structures and the use of interface interactions.