Carbon dots-triggered the fabrication of miniature g-C3N4/CDs/WO3 S-scheme heterojunction for efficient CO2 photoreduction

Production of high value-added solar fuels from sunlight and carbon dioxide (CO2) have attracted much interest for achieving carbon neutrality, yet the current photocatalytic CO2 reduction reaction (CRR) process still suffers from inactivation of inert molecules and severe charge recombination. Here, we report a versatile carbon dots (CDs)-triggered confined co-assembly strategy to integrate ultrafine tungsten trioxide (WO3)/CDs quantum dots with graphitic carbon nitride (g-C3N4) for the fabrication of miniature g-C3N4/CDs/WO3 Step-scheme (S-scheme) heterojunction. Without any sacrificial reagent, the optimal photocatalyst enables 99.5 % selectivity toward the production of CO, with the highest yield rate of 31.04 µmol‧g−1‧h−1 under the gas–solid phase reaction. In situ spectra investigation and density functional theory (DFT) calculations suggest that the bifunctional CDs not only trigger quantum-sized precise assembly of WO3 nanocrystal on the surface of g-C3N4 matrix without aggregation, but also mediate the interfacial charge transportation. Moreover, the established S-scheme electron transfer pathway favor the rapid charge separation and directional transfer, thus ensuring the maximum utilization of photo-generated charge carriers for efficient photocatalytic CRR. This work provides a new tactic for rational design and synthesis CDs-mediated S-scheme heterojunction to harness solar energy into high value-added solar fuel.