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

Abstract

In this article, the catalysts of hydrotalcite-derived Ni1.5Co0.5AlO nanosheet-supported highly dispersed Pt nanoparticles (Ptn/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 (O2, 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 Ptn/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 Pt2/Ni1.5Co0.5AlO catalyst showed the highest catalytic activities for soot combustion (T50 = 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/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.