Engineering active sites on hierarchical transition bimetal oxides/sulfides heterostructure array enabling robust overall water splitting.

Rational design of the catalysts is impressive for sustainable energy conversion. However, there is a grand challenge to engineer active sites at the interface. Herein, hierarchical transition bimetal oxides/sulfides heterostructure arrays interacting two-dimensional MoO/MoS nanosheets attached to one-dimensional NiO/NiS nanorods were fabricated by oxidation/hydrogenation-induced surface reconfiguration strategy. The NiMoO/NiMoS heterostructure array exhibits the overpotentials of 38 mV for hydrogen evolution and 186 mV for oxygen evolution at 10 mA cm, even surviving at a large current density of 500 mA cm with long-term stability. Due to optimized adsorption energies and accelerated water splitting kinetics by theory calculations, the assembled two-electrode cell delivers the industrially relevant current densities of 500 and 1000 mA cm at record low cell voltages of 1.60 and 1.66 V with excellent durability. This research provides a promising avenue to enhance the electrocatalytic performance of the catalysts by engineering interfacial active sites toward large-scale water splitting.