Effect of Surface Structure on Behaviour of RuO2 Electrodes in Sulfuric 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 "asgrown" 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.