Band gap and defect engineering of bismuth vanadate using La, Ce, Zr dopants to obtain a photoelectrochemical system for ultra-sensitive detection of glucose in blood serum

Abstract

Bismuth vanadate (BiVO₄) is a promising photoactive material for the design of photoelectrochemical (PEC) analytical devices for the non-enzymatic detection of glucose. In this work, un-doped and La/Ce/Zr doped BiVO₄ photo anodes were developed by spray pyrolysis coating to generate unique 2D hierarchical architectures using the facile ultrasonic spray coating technique without any complex pre or post-treatment. The influence of different dopants on the morphology and photoelectrochemical activity of BiVO₄ coatings was investigated. X-ray diffraction, scanning electron microscopy, UV-vis optical absorbance, and positron annihilation techniques were used to evaluate the structure, defects, and optical properties of BiVO₄ films. DFT simulation confirmed the Zr doping induced band gap reduction in the BiVO₄ lattice. The Zr doping on the Bi site in BiVO₄ lattice provided significantly low Bi and V-based defect density and a higher bulk diffusion length of charge pairs (4 times that of pristine) as well as charge transfer efficiency and this led to the foremost photocurrent for water splitting. The Zr-doped BiVO₄ photo anode showed remarkable sensitivity in glucose sensing. The sensitivity and limit of detection of the Zr-doped BiVO₄ PEC device towards glucose were 0.14 mA cm⁻² mM⁻¹ and 1.22 μM, respectively, in the concentration range of 1–7 mM. The system showed sensitive detection of glucose in blood serum. This is the first time that a 2D morphology electrode design consisting of Zr-doped BiVO₄, which leads to exceptionally high sensitivity for glucose sensing, has been reported.