Abstract: The upsurge of interest in the emergence of photocatalytic fuel cell systems (PFC) presents an efficient and environmentally friendly approach to wastewater treatment. In this work, a Z-scheme coupled with an S-scheme heterojunction electrode was used in the PFC, utilizing TiO₂/GO/g-C₃N₄ as the photoanode and BiOAc_1-xBr_x/ BiOBr as the photocathode. We systematically align the band structures between the anode and cathode, which facilitates the electron transfer between the electrodes. Our attempt successfully demonstrates that collaborative power generation facilitates the high efficiency of tetracycline hydrochloride (TC) degradation at both electrodes. The photoanode achieved a 94.87 % degradation rate for TC, while the photocathode exhibited a 96.33 % degradation rate after 2 h, surpassing pristine BiOBr and BiOAc by factors of ∼5.3 and ∼3.8, respectively. Furthermore, this work proposed a mechanism for electron generation, transport, and pollutant degradation mechanism in the PFC. Intermediate substances generated during the degradation of TC were analyzed through high-performance liquid chromatography-mass spectrometry (HPLC-MS) and ultraviolet photoelectron spectroscopy (UPS), while the optimal degradation pathway was confirmed using density functional theory (DFT). The findings of this work establish the feasibility of efficiently degrading pollutants through PFC treatment, introducing a novel system where various heterojunctions in bipolar materials collaborate with photocatalysis to effectively generate electricity and enhance pollutant removal.

Key words: Photocatalytic fuel cell, Wastewater purification, S-scheme heterojunction, Density functional theory