Au-Pd/mesoporous Fe2O3: 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.