Nanofiber-shaped Co₃O₄@In₂O₃ composite for high-performance enzymeless glucose sensing

Cobalt tetraoxide (Co₃O₄) holds great potential for enzymeless glucose detection due to its strong redox capabilities. However, its poor electrical conductivity limits the charge transfer and hence weakens its catalytic activity when utilized as an electrode in electrochemical sensors, such as an enzymeless glucose sensor. In this study, we developed an indium oxide (In₂O₃)-wrapped Co₃O₄ nanofibers (Co₃O₄@In₂O₃ NFs)-based electrochemical sensor for the enzymeless detection of glucose, with an ultra-low limit of detection (LoD) of 8.85 nM (S/N = 3), a wide detection range from 10 nM to 118 μM, and a high sensitivity of 1197.5 μA mM^-1 cm^-2. In addition, this sensor exhibits good selectivity, reproducibility, and long-term stability for over 30 days. The sensing performance of bare Co₃O₄ NFs towards glucose has been significantly enhanced by incorporating them within highly conductive In₂O₃, which is mainly attributed to the synergistic combination of the electrocatalytic activity of Co₃O₄ NFs, as the delicately designed core, and the excellent conductivity of In₂O₃, as the shell. Thus, this novel modified Co₃O₄@In₂O₃ NFs electrochemical composite has huge potential to be further developed for enzymeless glucose analysis in practical clinical settings.