Boosting the Removal of Diesel Soot Particles by the Optimal Exposed Crystal Facet of CeO2 in Au/CeO2 Catalysts

Optimized surface facet of the catalysts is an efficient strategy to boost catalytic purification of diesel soot as important components of atmospheric fine particles. Herein, we have elaborately constructed the nanocatalysts of Au nanoparticles supported on the well-defined CeO₂ (rod, cube, and polyhedron) with predominantly exposed facets of {110}, {100}, and {111}, respectively. The strong interaction between Au and CeO₂ with the optimal crystal facet is crucial to adjust the active site density for activated O₂, and the synergy effect of Au and the CeO₂{110} facet possesses the largest density of active sites compared with other crystal facets of {100} and {111}. The catalytic activity for soot combustion was tuned by exposed crystal facets of CeO₂. The Au/CeO₂-rod catalyst exhibits the highest catalytic activity (T₅₀ = 350 °C, TOF = 0.18 h^-1) and the lowest apparent activation energy (72 kJ mol^-1) during soot combustion. Based on the results of in situ Raman spectra, the formation and stability of oxygen vacancy located at the interface of the Au-O-Ce bond, boosting the key step of NO oxidation to NO₂, are dependent on the exposed crystal facets of CeO₂. It highlights a new strategy for the fabrication of high-efficient CeO₂-based catalysts for the removal of soot particles or other pollution.