Modulating g-C3N4-based van der Waals heterostructures with spatially separated reductive centers for tandem photocatalytic CO2 methanation

Abstract

Selective conversion CO2 to hydrocarbons over g-C3N4 photocatalyst remains a great challenge. Herein, efficient photocatalytic CO2 conversion to CH4 via a unique tandem pathway is achieved over strongly coupled van der Waals (vdW) heterostructure, composed of K+-intercalated crystalline g-C3N4 nanorods (CCNR) and N-doped porous carbon (NPC). A superior CH4 selectivity of 90.2% with an outstanding evolution rate of 11.79 µmol g−1 h−1 is demonstrated over optimized CCNR-NPC vdW heterostructure decorated with Pt species, without any sacrificial agents. The radial (intralayer) photoelectrons and axial (interlayer) photoelectrons transfer towards the exposed terminal NHx-sites at CCNR edge and the NPC-immobilized Pt-sites, respectively, giving rise to two separated spatially but cooperative reductive centers. At terminal NHx-sites, CO2 is activated to *CO intermediates, which are hydrogenated into CH4 at NPC-immobilized Pt-sites. This work will offer a new perspective for selective tandem photocatalytic CO2 conversion by designing hybrid photocatalysts with spatially separated but cooperative active centers.