Electrostatic charge transfer for boosting the photocatalytic CO2 reduction on metal centers of 2D MOF/rGO heterostructure

In this work, composite thin films comprising the 2D/2D MOF/rGO heterostructures assembled via Coulomb interaction are employed as the cocatalyst for photocatalytic CO2 reduction for the first time. The electrostatic charge transfer and the strong π-π interaction induced in the heterostructure effectively modulate the electronic structure of the metal centers in the conductive 2D MOF (Ni3HITP2), evidenced by Zeta Potentials, HR-TEM, XPS and XANES. The best thin-film catalyst with an optimal MOF/rGO ratio demonstrates a high CO evolution rate of 3.8 × 104 μmol h−1 gfilm−1 (0.46 min−1 in TOF) and a good selectivity of 91.74%, synergically contributed by the improved photoelectron harvesting on the rGO scaffold, the efficient charge transportation/transfer within the conductive and intimate 2D heterostructure, the coherent energy flow owing to aligned energy levels, and the enriched electron density at the isolated Ni-N4 sites boosted by electrostatic charge transfer.