Fabricating Mn3O4/β-Bi2O3 heterojunction microspheres with enhanced photocatalytic activity for organic pollutants degradation and NO removal

Novel porous sphere-like Mn3O4/β-Bi2O3 heterojunction photocatalysts were successfully synthesized by a heat treatment technique for photocatalytic degradation of organic pollutants (Rhodamine B (RhB), Bisphenol-A (BPA) and Methyl Blue (MB)) and oxidation removal of nitric oxide (NO). The XRD pattern results reveal that the β-Bi2O3 phase exists in all as-prepared samples. The UV–Vis spectra show that the optical adsorption ability of β-Bi2O3 has been greatly enhanced by loading with Mn3O4. The HRTEM results show that the Mn3O4/β-Bi2O3 heterostructures were successfully formed in the composite photocatalyst (S2 sample). The photocatalytic experiments reveal that 2 wt% Mn3O4/β-Bi2O3 heterojunction photocatalyst (S2) exhibited the most superior photocatalytic performance for NO removal and organic pollutants (RhB, MB and BPA) degradation. The experimental and DFT calculation results show that a type-II heterojunction can be formed at the interface between the Mn3O4 and β-Bi2O3 phases, which is very beneficial to promote the rapid separation of photogenerated carriers, thus producing excellent photocatalytic performances. This work provides insights into preparation of highly efficient visible light driven photocatalysts for pollutants removal.