TiO2 photoanodes with exposed {010} facets grown by aerosol-assisted chemical vapor deposition of a titanium oxo/alkoxy cluster

Photoelectrochemical water splitting is a promising technology for the development of solar fuels. Titanium dioxide (TiO2) is one of the most studied metal oxides in this field as a photoanode. Achieving its full potential requires controlling its morphology and crystallinity and especially the exposure of its most active crystal facets. Herein, we present the formation of nanostructured TiO2 photoanodes with anatase phase and high exposure of the {0 1 0} facet, the most active TiO2 phase and facet. TiO2 photoanodes were prepared from a Ti7O4(OEt)(20) titanium oxo/alkoxy cluster solution using aerosol assisted chemical vapor deposition. Characterization techniques such as SEM and TEM reveal that these TiO2 photoanodes consist of morphologies resembling the crystals of gypsum, sand and water found in nature, also known as desert roses. Furthermore, TEM and XRD analysis also reveals that the metastable anatase TiO2 phase is maintained up to 1000 degrees C and exceeds the typical anatase-to-rutile phase-transition temperature of 500-750 degrees C, a feature that could be exploited in the smart ceramics industry. Photoelectrochemical measurements show that these desert-rose TiO2 photoanodes achieve excellent photocurrent densities with an incident photon-to-current efficiency of similar to 100% at 350 nm and a faradaic efficiency for oxygen evolution of similar to 90%.