Energy resolved XPS depth profile of (IrO₂ , RuO₂ , Sb₂ O₅ , SnO₂ ) electrocatalyst powder to reveal core-shell nanoparticle structure

Synchrotron-based energy resolved XPS was used to characterize the structure of IrO2RuO2-coated Sb2O5SnO2 nanoparticles. Samples were heat treated at 300, 350, 400, 450 and 500 °C after chloride Ir and Ru precursors were added to Sb2O5SnO2. Photoelectron kinetic energies of 100, 350 and 1400 eV were employed to obtain an indication of the depth of elemental distributions and chemical shifts. It was shown that the electrocatalyst consists of a core of Sb2O5SnO2 enriched with Sb2O5 towards the surface, with a shell of IrO2RuO2 deposited on this core, and an outer layer of Sb2O5SnO2 over this shell. No significant chemical interaction occurs between IrO2RuO2 and Sb2O5SnO2. The energy resolved XPS depth profile technique is effective for studying core-shell materials. Copyright © 2010 John Wiley & Sons, Ltd.