Dual Functional Metal Oxide Nano-materials Enabled Sensors for both Non-enzymatic Glucose and Solid-state pH Sensing

Glucose sensing and pH sensing are of paramount importance in managing diabetes diseases and accurately monitoring acidity and alkalinity of the solution. To date, numerous reports have reported about solid-state pH sensing and metal oxide based non-enzymatic glucose sensing, however, there is an unmet challenge to realize dual functional sensing elements in a single unit for both glucose sensing and solid-state pH sensing. As a new class of multifunctional materials, high-temperature annealing enabled iridium oxide nanofibers, rhodium oxide nanocorals, cobalt oxide hollow fiber, and gold-doped iridium oxide nanomaterials were synthesized and then they are first employed as the sensing element to fabricate a novel dual glucose and pH sensor in this study. The as-prepared IrO2 nanofibers, Rh2O3 nanocorals, nitrogen-doped hollow Co3O4 nanofibers, and gold-doped IrO2 nanoparticles were systematically characterized and analyzed by advanced instruments, including X-ray powder diffraction, Scanning electron microscopy, Raman spectroscopy, Fourier transform Infrared Spectroscopy, thermogravimetric analysis, etc. Through electrochemical method analysis, the results show that as-developed dual sensors hold a good selectivity, repeatability, as well as stability toward glucose determination without losing varied solid-state pH sensing performance. For the respective of pH sensing, near the theoretical value of Nernst-constant is observed for IrO2 nanofibers based dual sensor on both bulky glassy carbon electrode and a miniaturized screen-printed electrode, whereas, the investigation shows sub-Nernst constant on the rest of sensing units on the glassy carbon electrode. This dissertation introduces a periodic table-directed method in predicting sensing performance, further benefitting material selection for the development of dual functional sensing applications.