Kinetics and Mechanisms for Photoelectrochemical Degradation of Glucose on Highly Effective Self-Organized TiO2 Nanotube Arrays

Abstract

The kinetics and mechanisms of photoelectrochemical catalytic degradation of glucose on self-organized TiO2 nanotube arrays (TNAs) were investigated. A thin-layer cell was used to obtain an exhausted reaction condition with which an overall degradation process of glucose could be identified including surface reaction on TNAs and mass transfer from body solution to the diffuse layer. Current-time (Iph-t) and the corresponding differential coefficient profiles were used to analyze the micro-processes of photoelectrochemical catalytic degradation. The initially generated photocurrents on glucose degradation versus glucose concentrations fits well with Langmuir adsorption isotherm, I0ph = 0.00008c0/(1+0.69274c0)+0.00034. This confirmed the adsorption of glucose on TNAs film catalyst was a single molecule layer adsorption, and the photoelectrochemical catalytic degradation reaction kinetics on TNAs surface belonged to a first-order reaction. After the initial quick reaction, three consecutive micro kinetic processes were revealed by the differential coefficient profiles (dIph/dt-t) of the glucose degradation profiles (Iph-t).