Photoelectrocatalytic Electricity and/or H2 Production from Alcohols: The Effect of TiO2 Film Thickness

The photoelectrochemical anodic reforming of alcohols was studied on a porous nanoparticulate TiO2 film which was illuminated with a 365 nm UV radiation. The photoinduced open circuit voltage (OCVph) and the produced photocurrent (I-ph) were dependent on the nature of the alcohol molecule and on the TiO2 film thickness. With increasing film thickness and/or alcohol concentration, the OCVph becomes more negative, acquiring values varying between -120 and -360 mV versus reference hydrogen electrode. This was followed by a corresponding increase in the I-ph. This behavior can be attributed to the possibility that characterizes a nanoparticulate porous TiO2 film to be penetrated by the electrolyte and depleted from the majority charge carriers (electrons in the conduction band). The optimum film thickness for the given UV radiation depends on the applied positive reversed bias potential and lies between 3 and 7 mu m, while the optimum alcohol concentration lies between 0.5 M and 1 M, depending on the nature of the alcohol present in the solution. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3522808] All rights reserved.