Photodeposition of RuOx Nanostructures on TiO2 Films with a Controllable Morphology

Abstract

RuO2/TiO2 catalysts have shown broad use in promoting a variety of photocatalytic phenomena, such as water splitting and the photodecomposition of organic dyes and pollutants. Most current methods of photodepositing ruthenium oxide species (RuOx) onto titanium dioxide (TiO2) films involve precursors that are either difficult to produce and prone to decomposition, such as RuO4, or require high-temperature oxidations, which can reduce the quality of the resulting catalyst and increase the risks and toxicity of the procedure. The present work demonstrates the photodeposition of RuOx onto TiO2 films, using potassium perruthenate (KRuO4) as a precursor, by improving substantially a procedure known to work on TiO2 nanopowders. In addition to demonstrating the applicability of this method of photodeposition to TiO2 films, this work also explores the importance of the material phase of the TiO2 substrate, outlines viable concentrations and photodeposition times at a given optical intensity, and demonstrates that the morphology of the photodeposited nanostructures changes from cauliflower-like spheroids to a matted, porous sponge-like structure with the addition of methanol to the precursor solution. This morphology change has not been documented previously. By providing an explanation for this difference in the morphology, this work provides both newer insights into the photodeposition process and provides an excellent foundation for future procedures, allowing a more targeted and controlled deposition based on the desired morphology. ©