Supercapacitive performances of mesoporous tremella-like CoFe₂O₄/C electrode material

Ferrous gluconate has been widely used in the treatment of iron deficiency anemia due to its good therapeutic effect, high utilization, and low toxicity. However, the improper management of expired waste ferrous gluconate may also result in the flow of excessive ferrous ion into the environment, which may do harm to the organisms in the world. For this purpose, expired waste ferrous gluconate was firstly recycled in the form of cobalt ferrite (CoFe₂O₄)/carbon (C) by a fluid method and a post-calcination at the different temperatures of 400 and 500°C, and the effect of the calcination temperature on the morphology, micro-structure, and supercapacitive performances was also studied. The results showed that the obtained dark-brown CoFe₂O₄/C powders exhibited the loose mesoporous tremella-like morphology and satisfactory electrochemical supercapacitive performances, in which CFO-400 delivered higher electrochemical performances than CFO-500 due to lower crystallinity, higher electrical conductivity, and higher surface area. For example, the specific capacitance of CFO-400 electrode was as high as about 503 F/g at 0.5 A/g in the three-electrode system, and it remained 106 F/g after 5000 cycles at 5.0 A/g with 86% capacity retention in the symmetrical two-electrode capacitor, showing satisfactory long cycle stability. No doubt, these results provided a new successful recovery strategy for the circular economy of expired ferrous gluconate.