Ruthenium Oxide Nanotubes Via Template Electrosynthesis

Ruthenium oxide nanotubes were fabricated by a single-step galvanostatic deposition using porous anodic alumina membrane as template. For the electrodeposition process, we used a electrochemical cell specifically designed in order to employ only 0.5 ml of 0.02 M RuCl3•xH2O solution. The deposition from a very small volume was specifically addressed owing to the high cost of ruthenium compounds, which could be of some relevance from an applicative point of view. Several techniques were used to characterize the samples prior to and after thermal treatment, which was carried out at different temperatures in order to study the crystallization process of the deposit. Raman spectroscopy of as-deposited nanotubes revealed the presence of RuO2 vibrating modes, while XRD patterns did not show RuO2 peaks, consequently the formation of a subnano-crystalline structure was proposed. After thermal treatment at different temperature above 600°C, they crystallized in the tetragonal form of RuO2. Both XRD analysis and Raman spectroscopy revealed that crystal size of the deposit grew with temperature up to 1000°C. SEM investigations showed the formation of nanotubes having an uniform average external diameter, while wall thickness changed throughout the height.