In Situ Construction of Closely Bonded S-Scheme BiOI@Bi₂O₂(OH)(NO₃) Heterojunctions for Boosted Visible-Light-Driven Photocatalytic Activity

The construction of S-scheme heterojunctions has proved to be an efficient strategy to overcome the drawbacks of individual photocatalytic materials. Nevertheless, fabricating an intimate interface with strong interfacial coupling in the S-scheme heterojunctions is a challenge. Given that Bi2O2(OH)(NO3) and BiOI share similar [Bi2O2]2+ unit slices in their crystal structures, we successfully prepare S-scheme BiOI@Bi2O2(OH)(NO3) heterojunction nanosheets with tight binding by linking [Bi2O2]2+ and I– by the in situ growth of BiOI layers onto the surface of Bi2O2(OH)(NO3) nanosheets. In comparison to a single Bi2O2(OH)(NO3) and BiOI nanosheet, the S-scheme heterojunction shows a much increased photocatalytic degradation efficiency for organic pollutants. The significant increase in photocatalytic performance is not only attributed to the formed S-scheme heterojunction, which is capable of establishing an ideal internal electric field (IEF), but also more critically, the carrier separation is greatly facilitated by the tight interfacial interaction between semiconductor nanosheets. This synthetic route provides a constructive idea to be extended to rationally design S-scheme heterojunctions with an intimately bonded interface.