Carbon nanosheets supporting Ni–N3S single-atom sites for efficient electrocatalytic CO2 reduction

Abstract Of various atomically dispersed metal catalysts, those based on single Ni atoms are among the most efficient electrocatalysts for CO2 reduction. However, the activity of these catalysts is determined by the coordination environment of Ni sites. Here, N and S co-coordinated Ni sites were successfully prepared using a nickel phosphorus trisulfide two-dimensional template to form a sandwich-like conjugated microporous polymer. As-prepared Ni single atom–based porous carbon nanosheets were proved to possess N/S co-coordination via X-ray absorption spectroscopy. As electrocatalysts for CO2 reduction, the prepared porous carbon nanosheets achieved over 95% CO selectivity rate and −7.8 mA cm−2 current density (−0.8 V vs. reversible hydrogen electrode). This performance could be attributed to the sheet-like morphology of the nanosheets with long-distance conductivity and the rich single N/S-coordinated Ni atoms with high activity. The fundamental understanding of manipulating such a coordination environment revealed in this study can be used to create versatile single-metal atom–based catalysts for high-efficient energy conversion.