Synthesis and application of tungsten oxide nanostructure for ascorbic acid sensing

Abstract

Engineered nanomaterials that exhibit enzyme-like activity are highly sought after for designing enzymeless sensors, which circumvent the need for costly enzymes. In this context, we synthesized tungsten oxide (WO3) nanostructures via the hydrothermal method and characterized them using various techniques. A slurry of the resulting WO3 nanostructure was prepared and drop-cast onto a screen-printed carbon electrode (SPCE) to construct an enzymeless sensor. The electrochemical characteristics of the WO3/SPCE sensor were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). An optimized WO3/SPCE sensor was electrochemically evaluated for ascorbic acid (AA) detection at varying concentrations employing CV analysis. The CV response exhibited a significant oxidation peak for AA, which gradually intensified with an increment in the AA concentration. The sensor demonstrated a linear response up to 1000 μM, high sensitivity (5.62 μA/μMcm2), and a detection limit (DL) of 0.6 μM. Moreover, the engineered enzymeless WO3/SPCE sensor displayed excellent selectivity, stability (94.5 % over 6 weeks), and fabrication reproducibility (RSD of 9.2 % across 7 devices). Thus, this WO3 nanostructure proves to be a promising candidate for the large-scale, cost-effective sensor development for AA detection and holds potential for the fabrication of enzyme-based biosensors.