RuO2-doping into high-aspect-ratio anodic TiO2 nanotubes by electrochemical potential shock for water oxidation

• Electrochemical potential shock results in homogenous incorporation of Ru into the whole nanotubes.
• Any complicated steps or facilities are not required for the doping.
• The high potential shock induced massive flow of RuO4− to positively-biased TiO2 NTs.
• Approximately 5 at.% Ru can be incorporated into high aspect ratio TiO2 NTs.

A novel method for homogenous incorporation of Ru (RuO2, or RuO3) into high aspect ratio anodic TiO2 NTs was studied. TiO2 NTs were prepared by anodization in HF based electrolyte, after which very short high applied potential, referred to as potential shock, was imposed on the TiO2 NTs in KRuO4 electrolyte. The high potential shock induced massive flow of RuO4− to positively-biased TiO2 NTs, resulting in the incorporation of Ru as a form of Ru, RuO2, and RuO3 in the TiO2 NTs. Optimal potential shock, which allowed the most suitable amount and incorporation state of Ru catalysts in TiO2 NTs, was determined by SEM, TEM, EDS, XPS, and LSV. It was demonstrated that electrochemical potential shock (simply imposed on the anodic TiO2 for a few seconds in the electrolyte of KRuO4) resulted in homogenous incorporation of Ru into the whole nanotubes without the need for any complicated steps or facilities.

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