Xingtian Zhao

Mesoporous CoO-supported palladium nanocatalysts with high performance for o-xylene combustion

The Pd-based catalysts have been widely studied for the combustion of volatile organic compounds, in which the roles of the Pd and the support are still not known clearly. In this study, mesoporous Co3O4 and CoO (i.e., meso-Co3O4 and meso-CoO) were prepared and used as support for the loading of Pd nanoparticles (NPs). The supported Pd samples performed much better than the supports for o-xylene combustion, in which the Pd/meso-CoO sample showed the best catalytic activity (T90% = 173 °C), giving rise to reaction rates at 170 °C 3.5 and 84 times higher than those over the Pd/meso-Co3O4 and meso-CoO samples, respectively. It has been established that the meso-CoO sample possessed strong ability to activate oxygen molecules to the active oxygen species, the loaded Pd NPs in a metallic Pd phase was beneficial for o-xylene adsorption, and the adsorbed o-xylene species could immediately react with the active oxygen species at the interface between Pd NPs and meso-CoO. Therefore, we conclude that the excellent catalytic performance of the Pd/meso-CoO sample was associated with its highly active Pd–CoO interface.

Au−Pd/mesoporous Fe 2 O 3 : Highly active photocatalysts for the visible-light-driven degradation of acetone

Three-dimensionally ordered mesoporous Fe2O3 (meso-Fe2O3) and its supported Au, Pd, and Au-Pd alloy (xAuPdy/meso-Fe2O3; x=0.08-0.72wt.%; Pd/Au molar ratio (y)=1.48-1.85) photocatalysts have been prepared via the KIT-6-templating and polyvinyl alcohol-protected reduction routes, respectively. Physical properties of the samples were characterized, and their photocatalytic activities were evaluated for the photocatalytic oxidation of acetone in the presence of a small amount of H2O2 under visible-light illumination. It was found that the meso-Fe2O3 was rhombohedral in crystal structure. The as-obtained samples displayed a high surface area of 111.0-140.8m2/g and a bandgap energy of 1.98-2.12eV. The Au, Pd and/or Au-Pd alloy nanoparticles (NPs) with a size of 3-4nm were uniformly dispersed on the surface of the meso-Fe2O3 support. The 0.72wt.% AuPd1.48/meso-Fe2O3 sample performed the best in the presence of 0.06mol/L H2O2 aqueous solution, showing a 100% acetone conversion within 4hr of visible-light illumination. It was concluded that the good performance of 0.72wt.% AuPd1.48/meso-Fe2O3 for photocatalytic acetone oxidation was associated with its ordered mesoporous structure, high adsorbed oxygen species concentration, plasmonic resonance effect between AuPd1.48 NPs and meso-Fe2O3, and effective separation of the photogenerated charge carriers. In addition, the introduction of H2O2 and the involvement of the photo-Fenton process also played important roles in enhancing the photocatalytic activity of 0.72wt.% AuPd1.48/meso-Fe2O3.