Bragg coherent diffraction imaging for characterisation of gold nano-catalysts

Abstract

In order to improve catalytic processes and decrease their costs, it is necessary to gain insight into the formation of active components and mechanisms of heterogeneous catalysts at nanoparticle level. For this purpose, the main objective of this project is to investigate and image defects in catalytic relevant gold nanocrystals, under operating conditions (high pressure and temperature) with nanoscale resolution. This will allow us to obtain information about the catalytic reaction mechanisms. With this aim, we wish to perform three-dimensional imaging of individual metallic nanoparticles under operando conditions using coherent diffractive imaging (CDI), identifying the catalytically active nanoparticles as well as their active sites during oxidation catalysis reactions. This will undoubtedly lead to a better understanding of the mechanisms during the catalytic reactions and improve catalysts design by optimizing their morphology, size and defects. We have a set of synthesized gold nanocrystals to be characterized at Soleil at the Bragg CDI beamline (called Cristal) with Dra Felisa Berenguer. The beam time is already granted for 2017 under the project number 20160959 (6 days).We wish to identify the catalytically active nanoparticles for CO oxidation reactions. This reaction is of prime importance because huge amounts of CO are emitted in the world and CO is a very toxic gas for human beings and animals. Currently the removal of CO from automobile exhaust is accomplished by the oxidation of CO in catalytic converters. This type of conversion is also applied for the CO removal from feed gas streams for polymer electrolyte membrane (PEM) fuel cells. (AU)