Incorporation of WO3 species into TiO2 nanotubes via wet impregnation and their water-splitting performance

Self-organized and highly ordered titanium dioxide (TiO2) nanotubes synthesized through anodization and wet impregnation were applied to incorporate tungsten trioxide (WO3) species uniformly throughout the walls of nanotubes. In this study, ammonium paratungstate (APT) was used as a precursor. The effect of APT molarity on the formation of WO3-TiO2 nanotubes was investigated using field emission microscopy, energy dispersion X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, photoluminescence, and X-ray photoelectron spectroscopy. The WO3-TiO2 nanotubes dipped in 0.3 mM APT aqueous solution exhibited better photoelectrochemical water-splitting performance under visible illumination. A maximum photocurrent of 2.1 mA/cm(2) with a photoconversion efficiency of 5.1% was obtained, which is approximately twice higher than that of pure TiO2 nanotubes. The findings were mainly attributed to higher charge carrier separation, which minimized the recombination losses and enhanced the transportation of photo-induced electrons in this binary hybrid photoelectrode. (C) 2012 Elsevier Ltd. All rights reserved.