Plasma tailoring in WTe2 nanosheets for efficiently boosting hydrogen evolution reaction

2D transition metal dichalcogenides (TMDs) have been considered as promising non-precious electrocatalysts for the hydrogen evolution reaction (HER).However,their limited active sites and poor electric conductivity pose a significant hurdle to their HER performance,resulting in a large overpotential.Here,we report the defect engineering in ultrathin tungsten telluride (WTe) nanosheets with semimetal nature to improve hydrogen evolution effectively.We find that the oxygen plasma etching imposes a cutting effect on WTenanosheets,resulting in a large number of tungsten vacancies.Particularly,the sample after plasma treatment for 10 min shows a feather-like structure with an overpotential of 251m V at 10 m A/cm~2and a Tafel slope of 94 m V/dec,which is 4 times lower than the Tafel slope of pristine nanosheets.Further first-principles calculations shed light on the evolution of defect-rich WTenanosheets and offer rational explanation to their superiority in efficient hydrogen evolution.