Co9S8 Nanosheet Coupled Cu2S Nanorod Heterostructure as Efficient Catalyst for Overall Water Splitting.

Electrocatalytic water splitting is a promising technology for large-scale hydrogen production. However, it requires efficient catalysts to overcome the large overpotentials in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, we report a novel heterostructure catalyst Co9S8/Cu2S on copper foam (Co9S8/Cu2S/CF) with multistep impregnation and electrodeposition. Due to the strong interfacial interaction, the interfacial electrons transfer from Co sites to S sites, which promote the adsorption of oxygen-containing intermediates, water molecules, as well as the dissociation of water molecules. Therefore, the heterostructure catalyst exhibits low overpotentials of 195 mV for OER and 165 mV for HER at 10 mA cm-2, respectively. Moreover, it only needs 1.6 V to realize water splitting at 10 mA cm-2 in a two-electrode cell. This work provides an efficient method to tailor the surface electronic structure through specific morphological design and construct a heterostructure interface to achieve alkaline water splitting.