文摘
The Pt/CeO<sub>2sub> nanocomposites of Pt nanoparticles partially confined in the mesopores of microsized mesoporous CeO<sub>2sub> (1.0% Pt/CeO<sub>2sub>-MM) or supported on the surface of CeO<sub>2sub> nanocubes (1.0% Pt/CeO<sub>2sub>-NC) with the same Pt loading of 1.0 wt % were prepared by the impregnation of microsized mesoporous CeO<sub>2sub> or CeO<sub>2sub> nanocubes with Pt(NO<sub>3sub>)<sub>2sub> aqueous solution, followed by the reduction with NaBH<sub>4sub> aqueous solution. 1.0%Pt/CeO<sub>2sub>-MM exhibits much higher catalytic activity for benzene oxidation than 1.0%Pt/CeO<sub>2sub>-NC. Compared to 1.0% Pt/CeO<sub>2sub>-NC, the reaction temperatures of T<sub>50sub> and T<sub>90sub> (corresponding to a benzene conversion = 50% and 90%) for 1.0% Pt/CeO<sub>2sub>-MM tremendously decreases by ΔT<sub>50sub> = 149 °C and ΔT<sub>90sub> = 196 °C, respectively. The turnover frequency (TOF) of 1.0% Pt/CeO<sub>2sub>-MM at 140 °C increases by 9.0 times as compared to that of 1.0% Pt/CeO<sub>2sub>-NC. The tremendous enhancement in the catalytic activity is due to a novel metal support interaction in 1.0% Pt/CeO<sub>2sub>-MM. The novel metal support interaction is theoretically studied by density function theory (DFT) calculation and experimentally studied by CO-TPR, CO-TPD, H<sub>2sub> pulse titration, and HRTEM. The theoretical and experimental evidence reveal that the partial confinement of Pt nanoparticles in the mesopores of microsized mesoporous CeO<sub>2sub> leads to a significant enhancement in the activity of the surface lattice oxygen around the interface between Pt nanoparticles and CeO<sub>2sub>, thus tremendously increasing the catalytic activity.
