Construction Of A Photocatalytic Microbial Fuel Cell Sensor Based On CuO/ZnO Photocathode And Its Detection Of Heavy Metals

The development of sustainable,low-cost,and responsive technologies for early warning and detection of heavy metals in water is critical to the health of ecosystems.Microbial fuel cells have great applications in emerging sensor systems due to their ability to operate stably over long periods of time and be self-powered.Its biofilm electrodes could be used as bio-recognition elements,and chemical detection can be achieved through changes in electrical signals.In this study,a photo microbial fuel cell was constructed using CuO/ZnO as the photocathode,and the detection performance of the microbial fuel cell as a sensor was improved by the synergistic effect of the microbial anode and the photocatalytic cathode.The main work was as follows.（1）CuO photocathodes are less stable due to the easy compounding of electron-hole pairs and their easy reduction by photogenerated electrons,so CuO/ZnO photocathodes were prepared on the basis of CuO photocathodes by electrodeposition with ZnO loading.The average current densities of the three electrodes were 38.52μA/cm²,90.36 n A/cm²,89.47μA/cm²,and CuO/ZnO photocathodes only decreased by 23%after 5000 s of illumination,which had better stability.（2）By changing the preparation conditions of the photocathode,different deposition times,deposition precursor solution formulations,and subsequent annealing treatments were investigated to obtain larger and more stable currents,and the experimental results showed that the photoelectric The electrode material prepared after annealing treatment has the best photoelectric chemical properties.（3）A photo microbial fuel cell was constructed as a sensor for heavy metals in wastewater by coupling a CuO/ZnO photocathode with a microbial anode.The detection of heavy metals Cu²⁺and Cd²⁺was carried out under light and dark conditions.We verified that the photocatalytic microbial fuel cell possessed better heavy metal detection performance under light conditions compared to dark conditions.The results showed higher inhibition rates and better linearity(R²=0.973for Cd²⁺)and a wider detection range(0.1-4 mg/L for Cd²⁺and 10-80 mg/L for Cu²⁺)for the photo microbial fuel cell sensor compared to the dark conditions.（4）Three other heavy metals(Hg²⁺,Zn²⁺and Cr⁶⁺)verified the universality of the photo microbial fuel cell sensor to detect heavy metals,and the inhibition rates of the three heavy metals were Cr⁶⁺:17.49%,Zn²⁺:12.51%and Hg²⁺:25.72%,respectively.After comparison,the toxicity magnitudes of the five heavy metals were:Cd²⁺>Cr⁶⁺>Zn²⁺>Hg²⁺>Cu²⁺.The detection mechanism of the photo microbial fuel cell sensor was proposed by UV-vis diffuse reflectance spectroscopy（DRS）and Mott-Schottky（M-S）curves.This work is the first to improve the performance of heavy metal detection using the electricity-producing properties of photo fuel cells,demonstrating the advancedness of photo microbial fuel cells as sensors and providing a new approach to the development of biosensors.