Feather-like few-layer WSe nanosheets grown on W substrates: an excellent electrocatalyst for the hydrogen evolution reaction.

Thin films of few-layer WS nanosheets and WSe nanosheets were directly grown on W substrates a scalable infrared-heating CVD method. The WSe nanosheets are in a unique feather-like assembly, and mainly composed of the 2H phase, while the presence of a metallic 1T phase was confirmed through atomic resolution TEM observation. Feather-like WSe nanosheets delivered excellent electrocatalytic performances for the HER in acid, including a low overpotential of 141 mV to yield a current at 10 mA cm, and superb long-term stability at high currents. The highly efficient electrocatalysis is mainly attributed to the unique feather-like morphology of the WSe nanosheets with numerous sharp barbules to help maximize the exposed edge sites, along with other beneficial factors including the presence of a 1T phase and slight O-doping.