Abstract
<title>Abstract</title> <p> Photocatalytic fuel cells can be used for organic waste treatment and power generation by combining photocatalytic technology with fuel cells. However, traditional photocatalytic fuel cells rely on UV-responsive TiO <sub>2</sub> -based photocatalysts and noble metal platinum cathodes, and the utilization of visible light is low and the cost is high, which restricts practical applications. In this study, high-performance and low-cost Cu <sub>2</sub> O photocathode materials were explored to replace precious metal platinum cathodes. Bi <sub>2</sub> O <sub>3</sub> photoanode materials and Cu <sub>2</sub> O photocathode materials were successfully prepared by low-energy hydrothermal method. By optimizing the ratio of photocatalyst, Nafion solution and absolute ethanol, uniform and dense photoelectrodes were prepared by drop coating method, and Bi <sub>2</sub> O <sub>3</sub> -Cu <sub>2</sub> O heterojunction dual-photoelectrode photocatalytic fuel cell (PFC) was constructed. At the same time, a series of characterization methods were used to characterize the crystal structure, elemental composition, and photoelectrocatalytic properties of Bi <sub>2</sub> O <sub>3</sub> photoanode and Cu <sub>2</sub> O photocathode. The degradation mechanism, electricity generation performance and stability of the system were investigated by free radical capture, electrochemical test and cycle stability experiment.The results show that the battery exhibits excellent photocatalytic ability and power generation ability in the degradation of methylene blue (MB). The degradation rate of MB by Bi <sub>2</sub> O <sub>3</sub> -Cu <sub>2</sub> O PFC system was as high as 96.46% after 80 minutes. The maximum power density, short-circuit photocurrent density and open-circuit voltage were 10.08µW/cm <sup>2</sup> ,0.075mA/cm <sup>2</sup> and 0.54V, respectively. The Bi <sub>2</sub> O <sub>3</sub> -Cu <sub>2</sub> O PFC still has good photocatalytic performance after 5 cycles, and the Cu <sub>2</sub> O photocathode has no obvious phase structure change verified by XRD and XRS. The innovation of this study lies in the construction of heterojunctions by Bi <sub>2</sub> O <sub>3</sub> -n-type and Cu <sub>2</sub> O-p-type semiconductors to achieve efficient separation of photogenerated carriers. At the same time, non-precious metal Cu <sub>2</sub> O is used instead of Pt cathode, which greatly reduces the system cost and has a good application prospect in the field of low-cost organic wastewater treatment and energy reuse. </p>