Titania Nanotube Supported Gold Photoanodes for Photoelectrochemical Cells

A major challenge to the use of photoelectrochemical cells for the production of hydrogen from water and solar energy is the low photoanode efficiency. These low efficiencies are largely due to losses associated with the recombination of the charge carriers and low photocatalytic activities. In this work, two strategies were investigated for improving the photoanode performance: producing the semiconducting oxide (TiO2) in the form of long nanotube arrays and incorporating gold nanoparticles onto the surface. Highly ordered TiO2 nanotube (TiNT) arrays were fabricated using an anodization process. By varying the conditions, TiNTs with different dimensions were fabricated. Gold nanoparticles with sizes that ranged from 3 to 12 nm were deposited onto selected TiNTs using a modified deposition precipitation method. Increasing the nanotube length resulted in increased photocurrents up to lengths that exceeded the diffusion length of electrons in TiO2 (similar to 20 mu m). The deposition of gold (Au) nanoparticles resulted in significantly improved electrocatalytic properties. The nonlinear correlation between photocurrent and particle size suggested that sites on the Au nanoparticles were not the most active sites for water oxidation. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3417096] All rights reserved.