Photoelectrodeposition of BiVO4 layer on FTO/WO3 photoanodes for highly efficient photoelectrocatalytic chemical oxygen demand sensor applications

Abstract

The research focus is on developing the photoelectrocatalytic (PEC) technique to obtain the simple, rapid, and nontoxic method for chemical oxygen demand (COD) sensor application. We have developed the heterojunction of a WO3/BiVO4 layer deposition on a fluorine-doped tin oxide (FTO) substrate using an electrodeposition method. The highlight of this development is the capability to immobilize a BiVO4 layer on the FTO/WO3 semiconductor electrode through our novel photoelectrodeposition method. A FTO/WO3/BiVO4 characteristics were studied to confirm the chemical composition, crystalline structure, morphology, optical properties, and charge transfer resistance. The results showed that the high efficiency of the BiVO4 layer deposited on the FTO/WO3 electrode improved the visible light absorption, surface morphology, and charge transfer rate and enhanced the PEC activities over the FTO/WO3 electrode by up to 2.5 times. The FTO/WO3/BiVO4 electrode was applied as a photoanode for COD determination using the designed PEC cell. The developed PEC cell exhibits relative standard deviation of 2.03% and percentage recovery of 98%, which indicate the method’s high precision and accuracy for COD determination. The proposed PEC cell for the COD sensor represents a simple, rapid, low-cost, environmentally friendly, and highly efficient method for COD monitoring in a wastewater treatment system.