Separate-type Pt-free photofuel cell based on a visible light-responsive TiO2 photoanode: Effect of hydrofluoric acid treatment of the photoanode

摘要

The present study deals with the effect of a hydrofluoric acid (HF) treatment of visible light-responsive TiO2 (Vis-TiO2) thin film photocatalysts on their photoelectrochemical performances. The Vis-TiO2 thin film photocatalysts have been prepared on Ti metal substrates by a magnetron sputtering deposition method and then treated by an HF solution. The HF treatment of Vis-TiO2 thin film photocatalysts leads to the dramatic enhancement of their photoelectrochemical performances under UV light and visible light irradiation. Moreover, separate-type Pt-free photofuel cells (SPFCs) constructed using the Vis-TiO2 thin films as photoanodes can generate electricity under light irradiation and simultaneously decompose methanol. The SPFC based on the Vis-TiO2 thin film photoanode etched by HF solution shows the enhanced cell performances with two times higher short-circuit current density and higher energy conversion efficiency than that based on the untreated Vis-TiO2 thin film photoanode. In addition to the increase of surface area and surface roughness, the enhanced conductivity by HF treatment, which is confirmed by Mott-Schottky analyses, is found to be responsible for improvement of cell performances of the SPFC.