Heterogeneous iridium oxide/gold nanocluster for non-enzymatic glucose sensing and pH probing

In this work, heterogeneous gold-doped iridium oxide nanoclusters (IrO₂–Au NCs) that are both pH-sensitive and glucose-responsive were synthesized through electrospinning followed by high-temperature calcination. The as-prepared IrO₂–Au NCs were systematically characterized using various advanced techniques including scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy. They were then employed as the sensing element to fabricate a sensor for both non-enzymatic glucose sensing and solid-state pH monitoring. Sensing performance of the IrO₂–Au NCs based dual sensor toward pH and glucose was evaluated using various electrochemical techniques, including potentiometric, cyclic voltammetry and amperometric techniques. The results show that the as-prepared IrO₂–Au NCs not only maintain accurate and reversible pH sensitivity derived from IrO₂, but also demonstrate good electrocatalytic activity resulted from Au toward glucose oxidation in alkaline medium at a low applied potential with a sensitivity of 21.20 μA mM^-1 cm^-2, a limit of detection of 2.93 μM (S/N=3) and a reasonable selectivity against various interferences. These features show that the as-prepared IrO₂–Au NCs hold great promise as a dual-functional sensing material for the development of a high-performance sensor for both solid-state pH and non-enzymatic glucose sensing.