Photodeposition of RuO Nanostructures on TiO₂ Films with a Controllable Morphology

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 (RuO ) 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 RuO 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.