Oxygen vacancy dependent photocatalytic CO2 reduction activity in liquid-exfoliated atomically thin BiOCl nanosheets

Identification of the crucial factor in the photocatalytic process is of great necessity for catalyst design. Here we successfully prepare atomically thin BiOCl nanosheets through liquid exfoliation and employ them as an example to explore the effects of entangled factors including quantum confinement, size effect, and defects generated along with the exfoliation process on the photocatalytic CO2 activity and selectivity. The experimental characterizations highlight that the solar fuel yield is linearly correlated with the oxygen vacancy concentration, illustrative of the oxygen vacancy dependent characteristic for atomically thin BiOCl nanosheets in the photocatalytic process. Further theoretical calculations illustrate that the weak p-σ bond involved in Bi-C-O-Bi geometry in BiOCl nanosheets is responsible for the improved CO yield and selectivity. This work may inspire more excellent work on the design of atomically thin 2D vdW photocatalysts.