Nitrogen-doped Hollow Co₃O₄ Nanofibers for both Solid-state pH Sensing and Improved Non-enzymatic Glucose Sensing

Nitrogen-doped hollow cobalt oxide nanofibers (Co₃O₄ NFs) with both glucose catalytic activity and pH sensitivity were fabricated through core-sheath electrospinning technique, followed by calcination. The as-developed nitrogen-doped hollow Co₃O₄ NFs were thoroughly characterized using various techniques, and then employed to fabricate a dual electrochemical sensor for both pH sensing and glucose sensing. The pH sensitivity of the developed nitrogen-doped hollow Co₃O₄ NFs demonstrated a Nernst constant of 12.9–15.9 mV/pH in the pH range of 3.0∼9.0 and 6.8–10.7 mV/pH in the pH range of 9.0∼13.0, respectively. The developed hollow cobalt oxides nanofibers sensor also possesses glucose sensitivity of 87.67 μA mM⁻¹ cm⁻², the limit of detection of 0.38 μM (S/N=3), and an acceptable selectivity against several common interferents in non-enzymatic glucose determination. High accuracy for monitoring glucose in human serum sample was also demonstrated. These features indicate that the as-synthesized nitrogen-doped hollow cobalt oxides nanofibers hold great potential in the development of a unique dual sensor for both solid-state pH sensing and superior non-enzymatic glucose sensing.