Effect of Surface Structure on Behavior of RuO2 Electrodes in Sulfuric Acid Aqueous Solution

The electrochemical properties of RuO₂ electrodes are studied by means of cyclic voltammetry, potential step, and impedance measurements in aqueous 0.5 mol/dm³ H₂SO₄ as a supporting electrolyte solution and applying the hanging electrolyte meniscus technique. Two types of the electrodes are used: bulk as-grown single-crystal having (101) exposed interface and 500 nm film produced by reactive RF magnetron sputtering at 450°C. The surface structure of the RuO₂ electrodes prepared by different techniques is defined from X-ray LAUE backscattering. Experimental data show that, for both RuO₂ electrodes, the charging components include a slow diffusion-controlled contribution, due to proton injection–ejection. The diffusion characteristics and the diffusion coefficients for the same electrodes are estimated and reported.