Metal organic framework-derived Co3O4/NiCo2O4 double-shelled nanocage modified activated carbon air-cathode for improving power generation in microbial fuel cell

Abstract To improve the power generation of the microbial fuel cell, activated carbon is modified by the Co 3 O 4 /NiCo 2 O 4 double-shelled nanocage, which prepared via a metal-organic framework method. When tested as cathodic material, the mesoporous Co 3 O 4 /NiCo 2 O 4 double-shelled nanocage with a large surface (112.9 m 2  g −1 ) exhibits higher open circuit potential (0.252 V) and higher exchange current density (19.70 × 10 −4  A cm −2 ). Moreover, the maximum power density of the air-cathode microbial fuel cell equipped with the 5% as-prepared catalyst is 1810 mW m −2 , 104% higher than the control. The morphology and crystal structure of Co 3 O 4 /NiCo 2 O 4 are investigated by the Transmission electron microscope and X-ray diffraction. X-ray photoelectron spectroscopy analysis indicates that there exists Co 3+ /Co 2+ and Ni 3+ /Ni 2+ redox couples in the catalyst, and divalence - trivalence - divalence redox cycles contribute to the improved oxygen reduction reaction performance and enhanced power output. Owing to the structural merits and improved electrochemical activity, the synthesized Co 3 O 4 /NiCo 2 O 4 double-shelled nanocage would be considered as a replacement of the new material for Pt in microbial fuel cell.