N-Doped Carbon-Supported CoCu-Layered Double Hydroxide Nanosheets as Antibacterial Oxygen Reduction Catalysts for Microbial Fuel Cells

The sluggish reaction kinetics of the oxygen reduction reaction (ORR) and the formation of a biofilm on the cathode prevent efficient and stable operation of microbial fuel cells (MFCs). In this work, zeolitic imidazolate framework-derived N-doped carbon-supported CoCu-layered double hydroxide nanosheets (CoCu-LDH@NC) were synthesized as a bifunctional cathode catalyst for MFCs. CoCu-LDH supported on CoO@NC induced the production of carbon nanotubes (CNTs) from the NC matrix. CNTs and CoCu-LDH nanosheets improved the atomic reaction efficiency and active area for the ORR. The high-speed electron-transfer channel was attributed to two-dimensional CoCu-LDH nanosheets and one-dimensional CNTs. The catalytic activity and stability of CoO@NC were sustained through the incorporation of CoCu-LDH nanosheets. The electronic interaction of CoCu-LDH and CoO@NC enhanced the ORR catalytic activities. CoCu-LDH nanosheets generated reactive oxygen species (ROS) and Cu+, improving the antibacterial activity to prevent the growth of biofilm for MFCs. CoCu-LDH@NC demonstrated superior oxygen reduction activity with a half-wave potential of 0.84 V and an onset potential of 0.89 V. The maximum power density and operating cycle of the MFCs assembled with CoCu-LDH@NC reached 1012 mW m–2 and 170 h, respectively. This work offers guidance to enhancing the ORR catalytic activity and stability by designing antibacterial ORR catalysts.