Proton insertion into ruthenium oxide film prepared by pulsed laser deposition

Electrochemical properties of ruthenium oxide (RuO₂) films with different degrees of crystallinity were studied. The RuO₂ films were grown by pulsed laser deposition at substrate temperatures from 30 to 400°C. At low temperatures, the amorphous phase of RuO₂ films was formed. At high temperatures, the crystalline phase of RuO₂ films was obtained. From the cyclic voltammetric study in H₂SO₄ solution, it was found that the current response for an electrode of the amorphous RuO, film was higher than that of the crystalline film. A proton diffusion length of larger than 5.8 nm was obtained on the RuO₂ film prepared at 30°C.