XPS/NRA investigations of particle size effects during the oxidation of Cu particles supported on oxidised Si (100)

In this study we investigate the effects of the particle size on the oxidation of supported Cu particles under equivalent experimental conditions with respect to temperature and pressure. We compare the results of oxidation of 4 and 15 nm Cu particles supported on oxidised Si(100) at room temperature and 573 K. At room temperature and p = 10 Pa, the oxidation of Cu0 to Cu2+ at the surface of 4 nm particles proceeds significantly slower than in the case of 15 nm particles. At 573 K and p = 0.1 Pa, a reverse trend is observed: oxidation of 4 nm particles from Cu0 to a Cu2+-oxide proceeds significantly faster than in the case of 15 nm particles. At both temperatures Cu0 was oxidised to Cu2+-oxide through an intermediate Cu+-oxide.