Investigation of Pt Catalyst Dynamics under DBD Plasma Jet During CO Oxidation via Operando DRIFTS

The understanding of catalyst dynamics under plasma exposure, given their impacts on reaction kinetics, is pertinent for effective catalyst design in nonthermal plasma (NTP)-assisted catalysis. However, it is obscured by complex plasma/catalyst interactions. Here, the dynamics of γ-Al₂O₃-supported Pt nanoparticles (NPs) during CO oxidation under dielectric barrier discharge (DBD) plasma jet exposure were investigated by operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to understand plasma effects on the nature and number of active sites in NTP-assisted catalysis. This work reveals the ability of the plasma to oxidize Pt, to affect supported Pt NP reconstruction, which changes the effective Pt dispersion, and to change the surface CO coverage, all of which can alter measured CO₂ turnover rates. Isolated reactant flow experiments identified plasma-activated O₂-derived species responsible for lower CO₂ turnover rates with plasma exposure at elevated temperatures, and transient DRIFTS measurements of CO–Pt binding were decomposed to identify a correlation in the prevalence of under-coordinated Pt sites with CO₂ turnover rates. The observed effects are consistent with the Eley–Rideal-type reaction of O₂-derived species with surface-bound CO to form CO₂. While NTP-assisted CO oxidation serves as a model reaction, insights from this study can be extended to NTP-assisted catalytic mechanisms, particularly those involving kinetically relevant CO–Pt binding such as methane reforming and CO₂ activation.