Novel and active Bi₂Zr_1.9M_0.1O₇ (M = Mn, Fe, Co, Ni) catalysts for soot particle removal: Engineering surface with rich oxygen defects via partial substitution of Zr‐site

Abstract To obtain more cost‐effective, non‐noble catalysts for soot particle combustion of diesel engine cars, Bi 2 Zr 1.9 M 0.1 O 7 (M = Mn, Fe, Co, Ni) compounds with partial lattice substitution have been designed and synthesized. All the substituted catalysts show significantly promoted activity, in the order of Bi 2 Zr 2 O 7 < Bi 2 Zr 1.9 Ni 0.1 O 7 < Bi 2 Zr 1.9 Co 0.1 O 7 < Bi 2 Zr 1.9 Fe 0.1 O 7 < Bi 2 Zr 1.9 Mn 0.1 O 7 . The presence of NO improves the activity of all the samples due to the generation of active surface nitrates/nitrites. It has been proven that all the modified catalysts possess weaker Zr–O bonds, which facilitates the generation of more surface defects. Density functional theory calculations have confirmed that a more defective catalyst has a lower vacancy formation energy and O 2 adsorption energy. Isotopic 18 O 2 labeling has also substantiated that a more defective catalyst has a faster gaseous O 2 exchange rate, thus improving the generation of more abundant soot reactive oxygen sites. The weakening of Zr‐O bonds is the inherent factor to improve the catalytic activity. Mn‐substitution can lead to the weakest Zr‐O bonds in Bi 2 Zr 1.9 Mn 0.1 O 7 , which thus shows the optimal catalytic activity. Notably, the complete soot combustion can be achieved even at 360°C on this catalyst.