Water Formation under Silica Thin Films: Real-Time Observation of a Chemical Reaction in a Physically Confined Space.

ABSTRACT: Using low-energy electron microscopy and local photoelectron spectroscopy, water formation from adsorbed O and H₂ on a Ru(0001) surface covered with a vitreous SiO₂ bilayer (BL) was investigated and compared to the same reaction on bare Ru(0001). In both cases the reaction is characterized by moving reaction fronts. The reason for this might be related to the requirement of site release by O adatoms for further H₂ -dissociative adsorption. Apparent activation energies (Eaapp ) are found for the front motion of 0.59?eV without cover and 0.27?eV under cover. We suggest that the smaller activation energy but higher reaction temperature for the reaction on the SiO₂ BL covered Ru(0001) surface is due to a change of the rate-determining step. Other possible effects of the cover are discussed. Our results give the first values for Eaapp in confined space.

SUBMITTER: Prieto MJ 

PROVIDER: S-EPMC6055755 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature