Alkali-Induced in Situ Fabrication of Bi2O4-Decorated BiOBr Nanosheets with Excellent Photocatalytic Performance

A simple alkali (NaOH) post-treatment approach assisted with light irradiation to in situ obtain Bi2O4 nanoparticle-decorated BiOBr nanosheets, brown BiOBr-0.01, is presented for the first time. Bi2O4 nanoparticles are formed due to a combined action of NaOH-induced dehalogenation and light triggered photogenerated hole (h+) oxidation processes on the surface of BiOBr nanosheets. Importantly, by varying the NaOH concertation in the post-treatment, the content of Bi2O4 phase in the hybrid structures can be easily tuned, and predominantly exposed highly reactive {001}-facet of BiOBr nanosheet can be well preserved. Significantly, without any foreign elements, the light absorption of as-prepared BiOBr-0.01 is extended to the near-infrared (NIR) region. In comparison with normal BiOBr, brown BiOBr-0.01 nanosheet shows superior photocatalytic activity for the dye degradation and microbial disinfection. Particularly, it exhibit excellent capability to photocatalytically reduce CO2 into CO and CH4, whereas the normal BiOBr is completely incapable for CO2 conversion under simulated sunlight irradiation. The exceptional enhancement is due to the Bi2O4 extended light absorption, efficient photogenerated e–/h+ pair separation, and the increased surface-adsorbed ability to reactants. This facile post-treatment method is promising for different bismuth-based systems and hence offers a path to a large variety of materials.