Di-defects synergy boost electrocatalysis hydrogen evolution over two-dimensional heterojunctions

Electronic modulation on the inert basal plane of transition-metal dichalcogenides(TMDs) through vacancy defect excitation, although extremely challenging, is urgent for understanding the factors that impact the hydrogen evolution reaction (HER) catalytic activity. Here, ultrathin WS₂ nanosheets with precise quantitative single atomic S-vacancy on the inert basal plane were flexible prepared through hydrogen peroxide etching strategy. The as-synthesized single atomic S-vacancy defect WS₂ (SVD-WS₂) nanoflake with the activated basal plane exhibited an impressive overpotential of 137 mV at a current density of 10 mA·cm^-2 and a Tafel slope of 53.9 mV·dec^-1. Furthermore, anchoring on the defect graphene matrix, the assembled two-dimensional (2D) stacking heterojunction exhibits further enhanced HER catalytic activity (an overpotential of 108 mV vs. 10 mA·cm^-2 and a Tafel slope of 48.3 mV·dec^-1) and stability (~ 10% decline after 9, 000 cycles), which attributed to the electronic structure modulation from the synergetic interactions between SVD-WS₂ and defect graphene. Our finding provides a smart defects introduce strategy to trigger high-efficiency hydrogen evolution over WS₂ nanosheets and a general 2D heterojunctions fabricated inspiration based on strong interaction interface.