A novel sea urchin-shaped copper-incorporated g-C3N4 nanoreactor for high-efficiency selectivity photocatalytic CO2 conversion into CO

Carbon graphene nitride (g-C3N4, CN) is a promising future for photocatalytic CO2 conversion into solar fuels. However, its photocatalytic activity and selectivity are limited to inadequate active sites, low visible light utilization rate, poor CO2 adsorption capacity, and rapid photo-generated carriers recombination rate. Herein, the supramolecular self-assembly method synthesized the sea urchin-like Cu-incorporated g-C3N4 (Cu-CNNTs) nanoreactors. The as-prepared Cu-CNNTs nanoreactor exhibits the photocatalytic reduction of CO2 into CO rate (16.09 μmol g-1h−1), 9.4 times higher than BCN and 3.33 times that of CNHS. The Cu-doping in the six-fold cavity of heptazine units as reaction active centers enrich both the photoelectrons and CO2 molecule. The superior structure of Cu-CNNTs shortens the transmission distance of electrons, accelerating the separation of electron-hole pairs and improving the utilization of light. Theory calculation results demonstrate that the activation energy barrier of the reduction of CO2 to CO is lower than that of CH4. Therefore, Cu-CNNTs exhibit enhanced selectivity and photocatalytic activity for converting CO2 to CO. This result provides valuable insights for the design and synthesis of highly selective and active carbon nitride-based multifunctional photocatalysts.