The slow cathodic oxygen reduction rate (ORR) of microbial fuel cells (MFCs) is still one of the main bottlenecks in its industrialization. As an ORR catalyst, metal oxides are expected to significantly enhance ORR efficiency by providing active sites, regulating reaction pathways, and enhancing stability. In this paper, four bimetallic oxide catalysts, CuO/Co3O4, CuO/ MnO2, CuO/NiO, and CuO/Fe2O3, were synthesized by sol–gel method, and their structural characteristics were characterized. The results showed that CuO/Co3O4 exhibited the largest specific surface area and optimized pore structure, and the synergistic effect of Cu and Co significantly improved the electrochemical performance. As the cathode catalyst of MFCs, CuO/Co3O4 shows high ORR catalytic activity, low charge transfer resistance, and good stability. In MFCs application, CuO/ Co3O4 catalyst achieved the maximum power density of 227 mW m− 2. In the five-cycle test, the output voltage is stable at about 240 mV, and the COD removal rate reaches 91.9%, which shows great application potential in wastewater treatment.

Screening and optimization of Cu-based bimetallic oxide cathode catalysts and their study on the electricity generation effect in microbial fuel cells
    Abstract
    1 Introduction
    2 Experimental section
        2.1 The synthesis method of CuOCo3O4
        2.2 The synthesis method of other bimetallic oxides
        2.3 MFCs building and running
    3 Results and discussion
        3.1 Materials properties
        3.2 Electrochemical performance test
        3.3 MFCs performance test
    4 Conclusions
    Acknowledgements 
    References

• Hua Liu(School of Chemistry and Chemical Engineering, Ningxia Key Laboratory of Solar Chemical Conversion Technology, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, People’s Republic of China) Corresponding author
• Chenxin Wang(School of Chemistry and Chemical Engineering, Ningxia Key Laboratory of Solar Chemical Conversion Technology, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, People’s Republic of China)
• Cheng Li(School of Chemistry and Chemical Engineering, Ningxia Key Laboratory of Solar Chemical Conversion Technology, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, People’s Republic of China)
• Xuan Yang(School of Chemistry and Chemical Engineering, Ningxia Key Laboratory of Solar Chemical Conversion Technology, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, People’s Republic of China)
• Cong Li(School of Chemistry and Chemical Engineering, Ningxia Key Laboratory of Solar Chemical Conversion Technology, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, People’s Republic of China)
• Zhi Song(School of Chemistry and Chemical Engineering, Ningxia Key Laboratory of Solar Chemical Conversion Technology, Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, People’s Republic of China)