Construction of embedded CdS nanosheets@PEA2PbBr4 nanoplate p-n heterojunction photocatalysts with spatial charge transfer for enhanced benzylic C(sp3)-H bond oxidation

Abstract

Metal halide perovskites (MHP) have emerged as promising new-generation photocatalysts due to their exceptional photoelectric properties. Here, we for the first time fabricate a novel CdS nanosheets@PEA2PbBr4 nanoplate p-n heterojunction using a simple anti-solvent method for photocatalytic activation of benzylic C(sp3)-H bond. The in-situ fabrication strategy enables the rapid growth of PEA2PbBr4 nanoplate to envelop the CdS nanosheets that serve as nucleation sites. This results in an embedded structure with large and intimate contact interface, providing abundant charge transfer channels. Additionally, the staggered band structure coupled with large difference in Fermi levels between the p-PEA2PbBr4 and the n-CdS form a strong internal electric field (IEF) that greatly accelerates the migration and realizes spatial separation of photoinduced electrons and holes within the heterojunction. Under visible light irradiation, the CdS@PEA2PbBr4 heterojunction displays notably improved photocatalytic C(sp3)-H bond oxidation activity. The optimized 5 % CdS@PEA2PbBr4 catalyst demonstrates a benzaldehyde (BAD) production rate of 4320 μmol g−1h−1, which is 5-folds higher than that of pure PEA2PbBr4 (950 μmol g−1h−1), and 18-folds greater than the blank CdS (240 μmol g−1h−1). Mechanistic study reveals that h+, O2− and 1O2 are the main active species contributing to C(sp3)-H bond oxidation. This work not only presents the first photocatalytic application of PEA2PbBr4, but also offers insights for developing MHP-based in-situ heterojunctions with desired nanostructure to further enhance photocatalytic performance.