Photoelectrochemical determination of intrinsic kinetics of photoelectrocatalysis processes at {001} faceted anatase TiO2 photoanodes

Abstract

The understanding of the intrinsic degradation kinetics of organic species at the reactive anatase TiO2 (001) surfaces under operational conditions is essential for the development of photoelectrocatalytic treatment of wastewater or polluted air. In this study, the intrinsic degradation kinetics of oxalic acid on the anatase (001) surface is successfully investigated by using a facile photoelectrochemical (PEC) method. A double-layered TiO2 photoanode with mainly anatase {001} facets exposed is purposely designed for the PEC measurements. The results reveal that the adsorption of oxalic acid follows the Langmuir adsorption model within the investigated concentration range. The PEC degradation profile can be fitted by two different first-order kinetic processes. The measured rate constant for the fast degradation processes is five times higher than that of the slow processes. The results confirm that the anatase TiO2 with exposed {001} facets possesses a higher reactivity than that of {101} faceted anatase TiO2.