Tunable Interfacial Charge Transfer in a 2D-2D Composite for Efficient Visible-Light-Driven CO₂ Conversion

Photocatalytic CO₂ conversion for hydrocarbon fuel production has been known as one of the most promising strategies for achieving carbon neutrality. Yet, its conversion efficiency remains unsatisfactory mainly due to its severe charge-transfer resistance and slow charge kinetics. Herein, a tunable interfacial charge transfer on an oxygen-vacancies-modified bismuth molybdate nanoflower assembled by 2D nanosheets (BMOVs) and 2D bismuthene composite (Bi/BMOVs) is demonstrated for photocatalytic CO₂ conversion. Specifically, the meticulous design of the Ohmic contact formed between BMOVs and bismuthene can allow the modulation of the interfacial charge-transfer resistance. According to density functional theory (DFT) simulations, it is ascertained that such exceptional charge kinetics is attributed to the tunable built-in electric field (IEF) of the Ohmic contact. As such, the photocatalytic CO₂ reduction performance of the optimized Bi/BMOVs (CO and CH₄ productions rate of 169.93 and 4.65 µmol g^-1 h^-1 , respectively) is ca. 10 times higher than that of the pristine BMO (CO and CH₄ production rates of 16.06 and 0.51 µmol g^-1 h^-1 , respectively). The tunable interfacial resistance of the Ohmic contact reported in this work can shed some important light on the design of highly efficient photocatalysts for both energy and environmental applications.