Boosting electrochemical oxygen evolution over yolk-shell structured O–MoS2 nanoreactors with sulfur vacancy and decorated Pt nanoparticles

Oxygen evolution reaction (OER) is considered as the bottleneck of electrochemical water splitting. Molybdenum disulfide (MoS2) with layered structure has great potential in utilization as OER catalyst. However, lower OER activity of MoS2-based catalysts compared with commercial IrO2 catalysts limited their practical applications. Here, we report the synthesis of monodispersed and uniform yolk-shell structured MoS2 nanoreactors (O–MoS2@Pt) with size distribution of 563 ± 14.8 nm through an oil-water microemulsion method. Interestingly, sulfur vacancy caused by oxygen doping could guide the Pt anchoring to generate uniform nanoparticles (ca. 10.9 nm) onto outer shell. Electron paramagnetic resonance (EPR), X-ray photoelectron spectra (XPS), and X-ray absorption fine structure (XAFS) are employed to synergistically investigate the anchor mechanism. The O–MoS2@Pt nanoreactor with highly activated basal plane and interface presented an overpotential of 244 mV at 10 mA/cm2, and a low Tafel slope of 53 mV/dec, which was much better than commercial IrO2 and most MoS2-based catalysts. Due to the prevention of agglomeration, enhanced mechanical stability, and regulation of gas release, all the developed yolk-shell structured nanoreactors exhibited negligible change of nanostructures and overpotentials after continuous cycling measurements for 24 h. In-situ XRD measurements indicated the endurability of the overall nanoreactor during the OER process. Density functional theory calculations revealed electron structures and thermodynamic reaction barriers can be efficiently modulated through introducing vacancy and Pt nanoparticles decorating, leading to highly improved OER activity. Our findings shed a light on the design of highly active catalyst for electrocatalytic water splitting through modulating electron structures and thermodynamic reaction barriers.