High‐Pressure Cell for <i>In Situ</i> Grazing Incidence XAS Characterization of Model Catalysts on Planar Supports

Abstract The growing interest in physically deposited model catalysts for uncovering complex structure‐activity relationships is spurred by the possibility of depositing nanoparticles of precise atomic structure and composition using cluster‐beam sources. However, the limitations accompanying these synthesis techniques, such as low deposition rates and flat sample geometry, present a challenge for in situ structural characterization using bulk‐sensitive methods, such as X‐ray absorption spectroscopy (XAS), especially at elevated pressures (1–100 bar). To overcome this challenge, we constructed an in situ XAS cell operating in a grazing incidence (GI) geometry. The GIXAS cell was used to investigate the structure of cluster‐beam‐generated Pd and Au 0.3 Ag 0.7 nanoparticles under CO 2 ‐to‐methanol hydrogenation conditions (230 °C, 20 bar, CO 2 :H 2 =1 : 3). These nanoparticles, with metal loading of 0.96–10 μg cm −2 , demonstrated stability and resistance to sintering upon activation in H 2 at 120 °C and catalytic conditions, revealed by in situ XAS. The promising results from our work will help bridge the gap in the investigation of model catalytic materials produced by gas‐phase cluster deposition at industrially relevant pressures and temperatures, which is vital for a mechanistic understanding of catalytic processes.