Antiphotocorrosion UV-Bi${}_2$O${}_3$@PANI photocatalyst rich in oxygen vacancy defects. Building processes, preparation mechanisms, and photocatalysis performance

Low content of oxygen vacancy defects (OVs) and limited resistibility to photocorrosion are the core problems in the heterogeneous photocatalytic processes of bismuth oxide (Bi${}_2$O${}_3$). Herein, the strategy of "ultraviolet (UV) light-inducing OVs" coupling with "polyaniline (PANI) combination inhibiting photocorrosion" is employed on the modification of Bi${}_2$O${}_3$. First, the high methylene blue (MB) degradation efficiency by UV${}_{3h}$-Bi${}_2$O${}_3$@PANI${}_{0.5wt\%}$ above 99.5% and the low Bi${}^{3+}$ dissolved concentration below 0.20 mg L${}^{-1}$ under visible light signify the high photocatalytic activity and stability. Then, the mechanisms for generation of OVs and inhibition of photocorrosion are proposed as follows. 1) Holes (h${}^{+}$) forming under irradiation, diffusing through the lattice, and reaching the surface of Bi${}_2$O${}_3$ can be regarded as a monatomic oxygen ion (O${}_S$${}^{-}$); 2) O${}_S$${}^{-}$ combines and continues to be oxidized by h${}^{+}$, leading to the generation of O${}_2$ with the OVs left in the lattice; 3) UV-Bi${}_2$O${}_3$ and PANI are excited to produce electrons/holes (e${}^{-}$/h${}^{+}$); 4) e${}^{-}$/h${}^{+}$ transfer in UV-Bi${}_2$O${}_3$@PANI heterojunction leads to the separation of h${}^{+}$ from UV-Bi${}_2$O${}_3$ and the inhibition of photocorrosion. Through the core problems being overcome, a new idea for the development and application of Bi${}_2$O${}_3$ with excellent performances in the field of water treatment is provided. (© 2022 Wiley‐VCH GmbH)