Fabrication of novel BiPO4/Bi4O5Br2 heterojunctions for improving photoactivity in N2 fixation and dye degradation

BiPO4/Bi4O5Br2 composites were synthesized via a straightforward solvothermal method and employed for the first time in photocatalytic N2 fixation and degradation of dyes. The synthesized BiPO4/Bi4O5Br2 exhibited exceptional photocatalytic performance under simulated solar light. The N2 fixation rate of BiPO4/Bi4O5Br2 was measured to be 370 μmol L−1 g−1 h−1, and the degradation rates of MO and RhB within 90 min were 95% and 99.9%, respectively. Various techniques were employed to characterize the prepared BiPO4/Bi4O5Br2 photocatalysts. The results revealed negligible alterations in both the specific surface area and the range of light absorption. However, the charge separation efficiency experienced substantial improvement as a result of the electron drift upon contact between BiPO4 and Bi4O5Br2, leading to a change in band position and the formation of a type-II heterojunction structure. Hence, the improvement of charge separation was deemed the primary factor affecting the photocatalytic performance.