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.