Photoelectrochemical properties of tungsten trioxide thin film electrodes prepared from facet-controlled rectangular platelets

The control of anisotropic crystal growth is critical for directing the orientation of crystal lattice planes, and it plays a key role towards understanding the effects of different planes on chemical reactions. Here, we report on the photoelectrochemical properties of plate-structured tungsten trioxide (WO3) thin films prepared from facet-controlled rectangular platelets of hydrotungstite (WO3 center dot 2H(2)O) and tungstite (WO3 center dot H2O), which are directly grown on tungsten substrates. The WO3 thin films, prepared via WO3 center dot 2H(2)O platelets, show relatively stable current for photoelectrochemical water splitting and methanol oxidation. On the other hand, the photocurrent of the WO3 thin films prepared via WO3 center dot H2O platelets was significantly decreased during the photoelectrochemical oxidation of water, which is likely due to the accumulation of partially oxidized intermediates such as peroxo species on the surface. These results indicate that the surface nanostructures of WO3 may have a significant influence on photoelectrode efficiency and selectivity for the catalytic oxygen evolution reaction.