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.