Reduction of N2O by H2 on the Ir(1 1 0) surface: oscillations in rate

The interaction of N2O with Ir(1 1 0) and the N2O–H2 reaction on that surface have been studied in the temperature range from 300 up to 800 K. Decomposition of N2O into N2 was observed, along with, surprisingly, N2O desorption or formation up to 450 K. Isothermal sustained oscillations in rate were found in the temperature range between 460 and 464 K for H2/N2O ratios close to 1. The reaction products are N2 and H2O. N2O oscillates in anti-phase with N2 and the maxima in H2O formation are “delayed” compared to the maxima in N2 formation during the oscillations. The period was close to 60 s. A possible explanation for the oscillations is proposed based on a built-up of atomic oxygen on the surface, produced by N2O decomposition, modifying the rate of N2O dissociation until oxygen is released in the form of water.