Three-dimensionally ordered macro-/mesoporous alumina（3DOM Al2O3）-supported cobalt oxide and platinum nanocatalysts（xPt/yCo3O4/3DOM Al2O3,Pt mass fraction（x%）= 0-1.4%,Co3O4 mass fraction（y%） = 0-9.2%） were prepared using poly（methyl methacrylate） templating,incipient wetness impregnation and polyvinyl alcohol-protected reduction.The resulting xPt/yCo3O4/3DOM Al2O3 samples displayed a high-quality 3DOM architecture with macropores（180-200 nm in diameter） and mesopores（4-6 nm in diameter） together with surface areas in the range of 94 to 102m^2/g.Using these techniques,Co3O4 nanoparticles（NPs,18.3 nm） were loaded on the 3DOM Al2O3 surface,after which Pt NPs（2.3-2.5 nm） were uniformly dispersed on theyCo3O4/3DOM Al2O3.The1.3Pt/8.9Co3O4/3DOM Al2O3 exhibited the best performance for toluene oxidation,with a T（90%） value（the temperature required to achieve 90%toluene conversion） of 160 ℃ at a space velocity of20000 mL g^（-1） h^（-1）.It is concluded that the excellent catalytic performance of the 1.3Pt/8.9Co3O4/3DOM Al2O3 is owing to well-dispersed Pt NPs,the high concentration of adsorbed oxygen species,good low-temperature reducibility,and strong interaction between the Pt and Co3O4 NPs,as well as the unique bimodal porous structure of the support.
Three-dimensionally ordered mesoporous Fe2O3（meso-Fe2O3） and its supported Au, Pd,and Au-Pd alloy（xA uP dy/meso-Fe2O3; x = 0.08–0.72 wt.%; 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 111.0–140.8 m^2/g and a bandgap energy of 1.98–2.12 eV. The Au, Pd and/or Au–Pd alloy nanoparticles（NPs） with a size of 3–4 nm were uniformly dispersed on the surface of the meso-Fe2O3 support. The 0.72 wt.% AuP d1.48/meso-Fe2O3 sample performed the best in the presence of 0.06 mol/L H2O2 aqueous solution, showing a 100% acetone conversion within4 hr of visible-light illumination. It was concluded that the good performance of 0.72 wt.%AuPd（1.48）/meso-Fe2O3 for photocatalytic acetone oxidation was associated with its ordered mesoporous structure, high adsorbed oxygen species concentration, plasmonic resonance effect between AuPd（1.48） 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 0.72 wt.%AuPd（1.48）/meso-Fe2O3.
