Bi-functional Ni3S2@MoS2 heterostructure with strong built-in field as highly-efficient electrolytic catalyst

Constructing heterojunction is an efficient way to enhance the catalytic activity for urea electrolytic catalysts, especially the heterostructure with a positive built-in field. Here, we prepare a core-shell catalyst of Ni3S2@MoS2 with Schottky junctions. The built-in field at the core/shell interface modifies the electron distribution and the Fermi level of MoS2 surface, which greatly enhances the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Further, with change of the shell thickness, we establish the correlation between the built-in field and catalytic properties. Ni3S2@MoS2 core-shell catalyst with shell thickness of about 10 nm delivers unprecedented UOR and HER performances of 1.336 V at 10 mA cm-2 and -0.098 V at -10 mA cm-2, respectively. This work develops an efficient route to synthesizing heterostructure catalysts with precise structure control and provides novel materials to optimize the microstructure of a heterogeneous catalyst system with pre-designable built-in field effects.