Cobalt valence modulating in CoOx incorporated carbon nanofiber for enhanced glucose electrooxidation

Glucose fuel cells (GFCs) driven by abiotic catalysts are promising green power sources for portable or wearable devices. In this work, a CoO_x incorporated carbon nanofiber (CoO_x@CNF) catalyst with mixed valences cobalt oxides have been developed through partial oxidation of pyrolyzed electrospun Co²⁺/poly acrylonitrile fibers. The cobalt valence modulating could be achieved via regulating the incorporation ratio of cobalt acetate in precursors or the oxidation temperature of the pyrolyzed fibers. Electrocatalytic analyses show that the presence of CoO in CoO_x@CNF will provide more active sites for glucose electrooxidation, and thus enhance the electrocatalytic performance significantly. As a result, the glucose fuel cell built with the CoO_x@CNF anode containing both CoO and Co₃O₄ delivered a maximum power density of 270 μW cm⁻², which is higher than that of other reported Co₃O₄ based GFCs. This work provides a simple strategy to develop excellent transition metal catalysts for GFCs to expand their applications in portable and wearable energy devices.