Long-term stability of Au nanoparticles on rutile-like Ti1-xFexO2 solid solutions for low-temperature CO oxidation

Abstract

Rutile and Fe-doped rutile were synthesized at low temperatures to support Au NPs. Selected samples were characterized using XRD, SEM-EDS, HRTEM, STEM-HAADF, H2-TPR, XPS, FTIR and DRIFT spectroscopy of adsorbed CO molecules. To enrich the interpretation, we performed DFT calculation on clusters of rutile, Fe-doped rutile and metallic gold interacting with CO molecules. Catalysts were tested in the CO oxidation reaction, focusing on the roles of activation-reaction time, Au loading, Fe-modification, and long-term aging on performance. Au-based Fe-doped rutile exhibited superior activity compared to the unmodified rutile catalyst. Long-term aging resulted in catalyst deactivation, but reactivation under hydrogen restored the high activity levels. Fe incorporation into rutile promoted the stabilization of the Au NPs by increasing the number of oxygen atoms on the surface, which act as pinning centers. This stabilization prevented the mobility and growth of the Au NPs, improving their dispersion.