High-efficient catalysts of core-shell structured Pt@transition metal oxides (TMOs) supported on 3DOM-Al2O3 for soot oxidation: The effect of strong Pt-TMO interaction

Diesel soot particles are important components of atmospheric fine particles, and the key factor in controlling soot emissions is the performance of catalysts in after-treatment systems. Herein, a series of high-efficient nanocatalysts of Pt@transition metal (Mn, Fe, Co, Ni, Cu) oxides (TMOs) core-shell nanoparticles (NPs) supported on 3D ordered macroporous (3DOM) Al2O3 (Pt@TMO/3DOM-Al2O3) were designed and synthesized. The strong Pt-TMO interaction at the optimized interface of Pt@TMO core-shell NPs induces the formation of coordination unsaturated active sites for activated reactants (O-2 and NO). Pt@TMO/3DOM-Al2O3 catalysts exhibit high catalytic activity dependence on the strong Pt-TMO interaction for soot oxidation, and Pt@CoOx/3DOM-Al2O3 catalyst shows the highest catalytic activity (T-50 = 357 degrees C, TOF = 2.76 S-1 x 10(-3)) and the lowest apparent activation energy (52 kJ mol(-1)) in the presence of O-2 (5%), NO (0.2%) and H2O (5%). In addition, Pt@TMO/3DOM-Al2O3 catalysts exhibit excellent H2O and SO2 resistances during catalytic soot oxidation. Based on the results of characterizations and density functional theory calculations, the coordination unsaturated Co-based active sites have efficient catalytic performance for NO oxidation to NO2 intermediate, which is an important reaction pathway for catalytic soot oxidation. Insight into the activity dependence on the strong Pt-TMO interaction is not only meaningful for development of advanced catalysts, but also supports the development of Pt@TMO nanoparticles for practical applications of emission reduction of diesel soot.