(560id) An Ambient Pressure XPS Study of Methane Dissociation and Oxidation on IrO2(110)

Recent studies demonstrate that the IrO₂(110) surface is highly active in promoting methane dissociation, with C-H bond cleavage occurring at temperatures as low as 100 K in ultrahigh vacuum. This finding stimulates interest in advancing the fundamental understanding of IrO₂(110) surface chemistry, and exploring the possibility of developing IrO₂-based catalysts for applications in the partial and complete oxidation of methane. In this talk, I will discuss recent AP-XPS (Ambient Pressure X-ray Photoelectron Spectroscopy) investigations of CH₄ oxidation on IrO₂(110) that we performed at methane partial pressures up to 1 Torr. We find that methane efficiently reduces an ~10 layer IrO₂(110) film on Ir(100) at temperatures above 500 K, with the rate of reduction depending on both temperature and CH₄ partial pressure. Complete reduction of the oxide film demonstrates that lattice oxygen migrates rapidly to the surface to sustain methane oxidation under the conditions studied. I will also discuss results obtained during the steady-state oxidation of CH₄ over IrO₂(110) and the nature of surface species observed during reaction for varying CH₄:O₂ mixtures and temperatures.