A Review: TiO2 based photoelectrocatalytic chemical oxygen demand sensors and their usage in industrial applications

Abstract

• PeCOD is a well-established method for the determination of chemical oxygen demand in water. • The design and optimized operation of an industrial TiO 2 based PeCOD device is discussed for the first time. • Photocatalytic systems generally rely on cycling between samples and calibration stages, requiring high stability and repeatability. The increase in global population, industrialization and need for water security has fostered a demand for novel technologies related to water treatment and purification. The oxygen demand of a given water matrix can provide useful information on the presence of organic compounds within a sample and can inform decisions on water use and treatment. Traditional oxygen demand measures are time consuming and require the use of harmful reagents. TiO 2 -based photoelectrochemical oxygen demand (PeCOD) methods offer a faster, more efficient, and accurate alternative to traditional analysis processes. These methods use TiO 2 -mediated photoelectrocatalysis (PEC) to oxidize organic contaminants. This paper reviews the recent synthesis methods of TiO 2 nanomaterials with respect to electrode preparation in COD sensors, fundamentals of TiO 2 photo/photo-electro-catalysis, TiO 2 based PeCOD sensors, and PeCOD sensor system cell design. PEC combines photocatalysis with electrochemical methods, which result in improved photocatalytic performance in a variety of applications. TiO 2 based PeCOD sensors are promising due to their intrinsic low cost, non-toxicity, chemical stability, and availability in sensing applications. Here in this paper, an innovative PeCOD sensor system cell design system is demonstrated. This review paper aims to provide a scientific and technical overview of TiO 2 PeCOD sensor systems implementable for large-scale environmental, soil, and gas sensing applications.