LAUSR

To improve the efficiency of catalytic materials, a better understanding of the catalytic processes is required from both the kinetic and material viewpoints. This can be achieved by using in situ imaging techniques allowing for the observation of catalytic processes under realistic conditions. Additionally, catalysts are composed of dispersed active elements and it is necessary to study the coupling between them at relevant scales. Finally, since applied formulations of catalysts use supported particles, the role and influence of the support on the catalytic activity/selectivity has to be gleaned. One convenient way to do so is to use so-called ‘inverse catalysts’ where the support is dispersed on a metallic surface, allowing to increase the metal/support interface and to observe the dynamic at this interface. In this frame, in situ environmental SEM allows the study of catalytic materials with various morphologies, under a wide pressure range (from 10 to 10 Pa) and at temperatures up to 1500°C. The growth of single layers of graphene has been observed during in situ CVD processes, demonstrating the high sensitivity of the SE signal to variations in the surface coverage and work function of the metal catalysts [1]. More recently, it was shown that the study of gas/solid interactions was possible through the imaging of nonlinear dynamics during the NO2+H2 reaction on Pt surfaces [2]. This proves that ESEM is sensitive enough to differentiate work function changes due to gas adsorption and surface reaction. In this work, we use graphene dispersed on Pt as model C/Pt inverse catalyst for NO2 hydrogenation.