Rational design of Ce-based mixed oxides via dopant synergy for enhanced oxygen release and combustion

Ce-based mixed oxides with enhanced oxygen release properties were rationally designed by substituting Ce sites in the fluorite lattice with group 3 and 4 metal cations. By combining H 2 -TPR and in operando XANES-TPR, dopants were classified into three categories based on their roles: intrinsically reducible cations, lattice-stabilizing cations with small ionic radii, and trivalent cations that promote oxygen vacancy formation. These dopants enhance oxygen release through distinct mechanisms, including direct redox participation, improved Ce reducibility, and facilitated oxygen diffusion. A clear synergistic effect was observed when co-doping elements from different categories, leading to significantly reduced oxygen release temperatures. Guided by this principle, a quaternary oxide (CePrZrSmO x ) exhibited the best oxygen releasing performance. This enhanced oxygen release behavior directly translated into superior soot combustion activity, demonstrating strong correlations between oxygen release properties and soot combustion. This work provides a rational strategy for designing high-performance ceria-based materials for enhanced oxygen releasing and catalytic combustion applications.