Synthesis and application of tungsten oxide nanostructure for ascorbic acid sensing

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/μM-cm²), 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.