Achieving high-proportioned 1T-MoS2 within heterostructures derived from polymolybdate-based complex for boosting electrocatalytic hydrogen evolution and oxygen evolution

Abstract

The fabrication of bifunctional electrocatalysts for hydrogen and oxygen evolution in aqueous environment has far-reaching significance. Especially, reasonable interface process regulation toward heterogeneous composites can make full use of the active sites and improve the electrocatalytic activity. In this study, we designed and synthesized NiS₂-MoS₂-based heterogeneous composites as efficient and stable electrocatalysts for hydrogen and oxygen evolution in alkaline electrolyte. The heterostructure was obtained by one-step hydrothermal ulfurization operation towards polymolybdate-based metal-organic complex. The composition and nanostructures can be tailored by modulating experiment parameter, realizing the phase-controlled synthesis and interface regulation: (1) High-percentage of 1T-MoS₂ can be achieved via selecting appropriate vulcanization time and thiourea concentration, benifiting for the higher electroconductivity and more active sites; (2) Regular and orderly vulcanization time promotes the gradual growth and aggregation of nanosheets; (3) The existence of nickel hydroxide improves the electrocatalytic stability for oxygen production performance. The optimized heterogeneous interfaces provide sufficient active sites and accelerate electron transfer. Consequently, the optimal heterogeneous nanosheets present low overpotentials of 33 and 122 mV at the catalytic current densities of 10 mA/cm² for HER and OER, respectively.