Solvothermal synthesis of a flower-like double Z-scheme PANI/Bi2Sn2O7/BiOBr/Ti photoanode and its performance in photocatalytic fuel cell

Photocatalytic fuel cell (PFC) provides a new method to degrade organic pollutants and recover their energy simultaneously. In this work, a novel flower-like hierarchical photoanode (PANI/Bi₂Sn₂O₇/BiOBr/Ti) was synthesized by solvothermal method and assembled with Cu cathode to form a PFC for rhodamine B (RhB) degradation and simultaneous power generation. The crystal structure, chemical composition, and morphology of the photoanode was characterized by a variety of analysis techniques. The photocatalytic activity of the ternary hierarchical composite photoanode was superior to that of single and binary composite photoanodes. Its maximum photocurrent density, maximum power density, degradation rate and FF were 0.241 mA·cm⁻², 21.52μW·cm⁻², 92.97 % (90 min) and 0.18, respectively. In addition, it still maintains high photocatalytic activity after five consecutive uses. Based on the analysis results of transient photocurrent (i-t), EIS, DRS spectrum, M-S curve and free radical capture experiments, the improvement of photocatalytic performance of PANI/Bi₂Sn₂O₇/BiOBr/Ti photoanode is attributed to the formation of dual Z-scheme heterojunction between PANI and BiOBr and between Bi₂Sn₂O₇ and BiOBr, which realizes the rapid separation and transfer of electron-hole pairs, and retains the strong oxidation of holes in VB of BiOBr and the strong reduction of electrons in LUMO of PANI and CB of Bi₂Sn₂O₇. This study provides a new research idea for the design and construction of high efficiency photoanode in PFC system.