Synergistic Effect of Pt and Dual Ni/Co Cations in Hydrotalcite-Derived Pt/Ni1.5Co0.5AlO Catalysts for Promoting Soot Combustion

In this article, the catalysts of hydrotalcite-derived Ni1.5Co0.5AlO nanosheet-supported highly dispersed Pt nanoparticles (Pt-n/Ni1.5Co0.5AlO, 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 Ni1.5Co0.5AlO nanosheets can increase the transfer mass efficiency of the reactants (O-2, NO, and soot) and the strong Pt-Ni1.5Co0.5AlO 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/Ni1.5Co0.5AlO 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/Ni1.5Co0.5AlO catalyst showed the highest catalytic activities for soot combustion (T-50 = 350 degrees C, TOF = 6.63 x 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/Ni1.5Co0.5AlO catalysts can promote the vital step of catalyzing NO oxidation to NO2 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.

Automated summary

In this article, highly dispersed Pt nanoparticles supported on Ni1.5Co0.5AlO nanosheets derived from hydrotalcite were fabricated using the gas-bubble-assisted membrane-reduction method. The specific porous structure of the Ni1.5Co0.5AlO nanosheets enhanced mass transfer efficiency and the interaction between Pt and Ni1.5Co0.5AlO promoted the mobility of lattice oxygen and the formation of surface-oxygen vacancies. The Pt-n/Ni1.5Co0.5AlO catalysts exhibited excellent catalytic activity and stability in diesel soot combustion, with the Pt-2/Ni1.5Co0.5AlO catalyst showing the highest activity. The synergistic effect of Pt and dual Ni/Co cations in the catalysts promoted the oxidation of NO to NO2 and provided new strategies for reducing the use of noble metals in high-efficient catalysts.