One-pot synthesis of MoS2/WS2 ultrathin nanoflakes with vertically aligned structure on indium tin oxide as a photocathode for enhanced photo-assistant electrochemical hydrogen evolution reaction

A hierarchical structure composed of vertically aligned ultrathin two dimensional (2D) MoS2/WS2 nanosheets is fabricated through a facile one-pot hydrothermal reaction. Scanning electron microscope (SEM), transmission electron microscope (TEM) and photoluminescence (PL) indicate that the MoS2/WS2 hybrid shows ultrathin nanoflakes with a thickness of 2-10 nm, and the as prepared heterostructure markedly enhances the separation of electro-hole pairs. Benefiting from the integrated W-doped MoS2, the vertically aligned nanostructure exhibits a moderate degree of disorder and increased active surface area. Electrochemical measurements (cyclic voltammetry (CV), linear sweep voltammetry (LSC) and electrochemical impedance spectroscope (EIS) under light illumination or in dark) indicated that the MoS2/WS2 hybrid (especially the hybrid with Mo : W of 1/1) exhibits much better photo-and electrochemical performance than its counterpart of pure MoS2 or WS2, which made it a promising photocathode for electrocatalytic hydrogen evolution reaction (HER) by photo-assistance.