Ultrathin Tin Monosulfide Nanosheets with Exposed (001) Plane for Efficient Electrocatalytic Conversion of CO2 into Formate
Current Sn-based materials are ideal catalysts developed to drive the electrochemical conversion of CO2 to formate, but competing proton reduction to hydrogen is an ever-present drain on catalytic selectivity. Herein, we reported a reliable electrochemically exfoliated route, with the assistance of alternate voltage, for large-scale preparation of two-dimensional (2D) ultrathin tin monosulfide nanosheets (SnS NSs), which feature a large lateral size of 1.0 μm with a thickness of ~5.0 nm. Systematic electrochemical studies demonstrated that the achieved SnS NSs exhibited an outstanding electrocatalytic activity towards CO2 reduction reaction (CO2RR) into formate product, as evidenced by a considerable Faradaic efficiency (F.E.) of 82.1%, a high partial current density of 18.9 mA cm-2 at -1.1 V, and a low Tafel slope of 180 mV dec-1. Further, using electrode prepared from resulting SnS NSs by particle transfer method, a remarkably high formate F.E. over 91% was achieved in a wide potential window. Such high performance renders the SnS NSs among the best reported tin sulfide-based CO2RR electrocatalysts. Theoretical calculations coupling with comprehensive experimental studies demonstrated that the synergistic effect between ultrathin layered architecture and dominantly exposed (001) plane of SnS NSs accounted for its uniquely efficient catalytic activity for CO2RR.