Synergistic Effect of Pt and Dual Ni/Co Cations in Hydrotalcite-Derived Pt/Ni(1.5)Co(0.5)AlO Catalysts for Promoting Soot Combustion

In this article, the catalysts of hydrotalcite-derived Ni(1.5)Co(0.5)AlO nanosheet-supported highly dispersed Pt nanoparticles (Pt(n)/Ni(1.5)Co(0.5)AlO, where n% is the weigh percentage of the Pt element in the catalysts) were elaborately fabricated by the gas-bubble-assisted membrane--reduction method. The specific porous structure formed by the stack of hydrotalcite-derived Ni(1.5)Co(0.5)AlO nanosheets can increase the transfer mass efficiency of the reactants (O(2), NO, and soot) and the strong Pt–Ni(1.5)Co(0.5)AlO interaction can weaken the Ni/Co-O bond for promoting the mobility of lattice oxygen and the formation of surface-oxygen vacancies. The Pt(n)/Ni(1.5)Co(0.5)AlO catalysts exhibited excellent catalytic activity and stability during diesel soot combustion under the loose contact mode between soot particles and catalysts. Among all the catalysts, the Pt(2)/Ni(1.5)Co(0.5)AlO catalyst showed the highest catalytic activities for soot combustion (T(50) = 350 °C, TOF = 6.63 × 10(−3) s(−1)). Based on the characterization results, the catalytic mechanism for soot combustion is proposed: the synergistic effect of Pt and dual Ni/Co cations in the Pt/Ni(1.5)Co(0.5)AlO catalysts can promote the vital step of catalyzing NO oxidation to NO(2) in the NO-assisted soot oxidation mechanism. This insight into the synergistic effect of Pt and dual Ni/Co cations for soot combustion provides new strategies for reducing the amounts of noble metals in high-efficient catalysts.