IrO2-based disperse-phase electrocatalysts: a complementary study by means of the cavity-microelectrode and ex-situ X-ray absorption spectroscopy.

In this work, IrO(2)-based powders are screened by cyclic voltammetry for the determination of the electrochemical active sites and for the qualitative evaluation of the iridium atoms speciation. All results are obtained using a cavity-microelectrode as powder holder, thus exploiting the features of this innovative tool, whose best potentialities have been recently introduced by our group. All the studied materials have been prepared by the sol-gel technique and differ in calcination temperature and method of mixing the metal oxide precursors. The electrochemical results are complemented with the information obtained by X-ray absorption spectroscopy (XAS), that give insights on the local structure of each selected sample, confirming the trends found by cyclic voltammetry and give new and unexpected insights on the powder structural features.