Bidirectional acceleration of carrier separation spatially via N-CQDs/atomically-thin BiOI nanosheets nanojunctions for manipulating active species in a photocatalytic process

Abstract

Nitrogen-doped carbon quantum dots (N-CQDs) modified atomically-thin BiOI nanosheets nanojunctions have been controllably prepared. The obtained BiOI consisted of 1–2 [Bi–O–I] units, which is the thinnest BiOX material reported so far. The atomically-thin structure was designed to accelerate carrier transfer among the BiOI nanosheet interior while the N-CQDs were constructed to facilitate surface charge carrier separation. Bidirectional acceleration of carrier separation can be achieved via this unique structure for both the materials interior and the surface. After the N-CQDs were modified on the BiOI, the photocatalytic activity of the N-CQDs/BiOI material greatly improved under visible light and UV irradiation. Through multiple characterizations, it can be found that the active species during the photocatalytic process can be manipulated. The modified N-CQDs could activate molecular oxygen via single electron reduction under visible light irradiation. Both ˙OH and O₂˙⁻ can be obtained from N-CQDs/BiOI materials under UV irradiation and N-CQDs could further increase the active species concentration. This study provides an approach to tune the active species for pollutant removal, selective organic synthesis or donating abundant hot electrons for CO₂ photoreduction.