Chronoamperometry-induced transmittance changes approach to detect aqueous sodium ion solutions using tungsten oxide thin films

Abstract

A simple, inexpensive method to detect sodium ions from aqueous solutions is reported in this paper. The method of detection based on transmittance changes observed in tungsten oxide films on.Tungsten oxide is deposited on ITO glass substrate by continuous electrodeposition method from Peroxo Tungstic Acid precursor. Chronoamperometry at a cathodic potential of −1V was performed on the sample in different concentrations (10 mM-150 mM) of NaCl solutions prepared in TRIS buffer solvent. UV–VIS-NIR transmittance in NaCl solutions was measured for the sample before and after chronoamperometry, and the corresponding transmittance changes (ΔT) were recorded. Due to the formation of tungsten bronze, the transmittance of the sample decreases during chronoamperometry. It was observed that the transmittance change increases with the NaCl concentration, and in the NIR wavelength range, the transmittance change observed was maximum. The sensor has a linear response in the range of 10 to 150 mM Na+ and excellent selectivity towards N+ as compared to interfering ions K+ and Ca2+. Its straightforward design, higher response, and selectivity make sodium detection in food sectors and health monitoring possible.