Coordination tailoring of Cu single sites on C3N4 realizes selective CO2 hydrogenation at low temperature

CO2 hydrogenation has attracted great attention, yet the quest for highly-efficient catalysts is driven by the current disadvantages of poor activity, low selectivity, and ambiguous structure-performance relationship. We demonstrate here that C3N4-supported Cu single atom catalysts with tailored coordination structures, namely, Cu-N4 and Cu-N3, can serve as highly selective and active catalysts for CO2 hydrogenation at low temperature. The modulation of the coordination structure of Cu single atom is readily realized by simply altering the treatment parameters. Further investigations reveal that Cu-N4 favors CO2 hydrogenation to form CH3OH via the formate pathway, while Cu-N3 tends to catalyze CO2 hydrogenation to produce CO via the reverse water-gas-shift (RWGS) pathway. Significantly, the CH3OH productivity and selectivity reach 4.2 mmol g-1 h-1 and 95.5%, respectively, for Cu-N4 single atom catalyst. We anticipate this work will promote the fundamental researches on the structure-performance relationship of catalysts.