Vanadium-doping in interlayer-expanded MoS2 nanosheets for efficient electrocatalytic hydrogen evolution reaction
Two-dimensional layered MoS2 nanosheets are regarded as a promising catalyst for electrocatalytic hydrogen generation but suffer from limitations of catalytically inert basal planes and poor intrinsic conductivity. In this work, we report a simple hydrothermal method to synthesize the defect-rich MoS2 nanosheets featuring vanadium (V) doping, widely expanded interlayer spacings, and high content of metallic 1T-phase towards efficient hydrogen evolution reaction (HER). The structural characteristics of V(IV)&V(II) co-doping, mixed 1T&2H phases and wide interlayer expansion endow the nanosheets with plentiful disorders and rich defects, thereby resulting in abundant active sites. Furthermore, the V(IV)&V(II) co-doping brings in electronic benefits of narrowed bandgap, improved intrinsic conductivity and optimized hydrogen adsorption free energy of basal planes. By tuning the V dopant content, the 10%V-MoS2 catalyst shows an optimized HER performance with a low overpotential of 146 mV at 10 mA cm-2, and a small Tafel slope of 48 mV dec-1, long operation stability of 80 h. Our work opens up new opportunities for improving electrochemical HER performance of layered transition metal dichalcogenides (TMDs) by synergistic structural and compositional modulations.