Secondary Ion Mass Spectrometric Studies on the Formation Mechanism of IrO 2 /ZrO 2 Based Electrocatalytic Thin Films

Abstract Secondary ion mass spectrometry (SIMS) was used to analyse the formation mechanism of IrO 2 /ZrO 2 film electrodes. The coating mixtures with compositions 20% Ir+80% Zr and 50% Ir+50% Zr prepared on titanium supports from alcoholic solutions of IrCl 3 .3H 2 O and ZrOCl 2 .8H 2 O precursors were heated to specified temperatures and analysed by SIMS. The process of the electrode film evolution was followed via concentration depth profiles of O − , Cl − , IrO   −   2 , ZrO   −   2and TiO   −   2selected species. It was found that at lower temperatures and lower noble metal contents, the governing mechanism of oxide formation is hydrolysis, while at higher temperatures and higher noble metal concentrations the oxidative mechanism of film formation prevails. The surface accumulation of IrO   2 , observed by SIMS at 500 °C for films with less than 50% IrO   2content, and of ZrO   2 , observed for films with over 50% IrO   2 , was confirmed by emission Fourier transform infrared measurements. No reaction between film components or between coatings and support was identified in the systems investigated. The results are in harmony with, and complementary to, those of former measurements by RBS and WAXS.