In situ plasmonic sensing of platinum model catalyst sintering on different oxide supports and in O2 and NO2 atmospheres with different concentrations

Artikel i vetenskaplig tidskrift, 2015

Improved understanding of thermal deactivation processes of supported nanoparticles via sintering is needed in order to increase the lifetime of catalysts. To monitor sintering processes under industrially relevant application conditions, in situ experimental methods compatible with elevated temperatures, high pressures and harsh chemical Environments are required. Here, we experimentally demonstrate the applicability of in situ indirect nanoplasmonic sensing (INPS) to investigate the sintering of Pt model catalysts on flat alumina and silica supports in O2 and NO2 atmospheres in real time and under operating conditions Moreover, by means of finite-difference time-domain (FDTD) electrodynamics simulations, we establish a generic scaling approach to account for different inherent sensitivities of INPS sensor platforms featuring dielectric support layers with different refractive index. Based on these findings, we identify a universal, support- and sintering-environment-independent correlation between INPS centroid shift signal and mean Pt particle size during the sintering process. As a first demonstration of the new possibilities offered by INPS and the obtained universal scaling to study sintering processes under different applied conditions, we investigate the dependence of the sintering rate of a SiO2-supported Pt model catalyst on the O2 concentration in the Ar carrier gas. We find a clear dependence of the sintering rate on the O2 concentration in the 0.05 to 0.5 % O2 concentration range.