Electron acceptor design for 2D/2D iodinene/carbon nitride heterojunction boosting charge transfer and CO2 photoreduction

Harvesting value-added products by CO2 reduction through photocatalysis is a sustainable approach. Against halogen-doping treatment, few-layer iodinene (FLI2) was used innovatively to construct 2D/2D van der Waals heterojunction with carbon nitride nanosheets (CNNS) for CO2 reduction under visible light irradiation. The photocatalyst achieved an enhanced CO production rate of 34.22 μmol g-1h−1, which was 7.76 times as pristine CNNS. Improved activity was attributed to FLI2/CNNS maintained tri-s-triazine crystal structure and polymeric framework of CNNS. FLI2/CNNS formed a contact interface by van der Waals force, where FLI2 served as an electron acceptor and CNNS acted as an electron donor, beneficial for electron transfer. This carrier migration tendency in FLI2/CNNS was confirmed by the DFT calculation of Fermi level and electron density distribution, which led to increased charge separation and decreased charge recombination. This work proposes the novel 2D/2D FLI2/CNNS and highlights the potential of metal-free heterojunction for efficient photocatalysis.