BiVO₄-based coatings for non-enzymatic photoelectrochemical glucose determination

BiVO₄ is known as a promising material for the design of analytical systems dedicated for non-enzymatic photoelectrochemical (PEC) glucose determination. In this work BiVO₄ coatings were deposited on fluoride-doped tin oxide substrate by simple sol-gel method. The influence of different stabilizers, such as polyethylene glycol, urea, citric acid and polyvinyl alcohol (PVA) on the morphology and photoelectrochemical activity of the BiVO₄ coatings was investigated. X-ray diffraction, scanning electron microscopy, UV–vis optical absorbance and photoluminescence techniques were used to evaluate structural and optical properties of BiVO₄ films. PEC performance was characterized by means of voltammetry, electrochemical impedance spectroscopy and chronoamperometry. It is shown that the combination of urea and polyvinyl alcohol leads to the formation of BiVO₄ coatings with lower charge transfer resistance as well as higher affinity towards adsorption of glucose, resulting in higher sensitivity of these photoelectrodes in glucose sensing. Sensitivity of BiVO₄ coatings synthesized with urea (Bi_Urea) or with urea and PVA (Bi_Urea_PVA) towards glucose was 0.0033 mA cm⁻² mM⁻¹ and 0.0056 mA cm⁻² mM⁻¹, respectively. The limit of detection was estimated to be 7.94 μM for Bi_Urea and 6.87 μM for Bi_Urea_PVA.