Exposed crystal facet tuning of CeO2 for boosting catalytic soot combustion: The effect of La dopant

The exposed crystal facets are crucial to heterogeneous catalysis. Herein, the facet controlled Ce1_xLaxO delta (0 <= x <= 0.30) nanocomposites have been constructed elaborately via a hydrothermal route and used for soot abate-ment. The catalysts were characterized by XRD, TEM, Raman, FT-IR, XPS, H-2-TPR, and so forth. With the increasing content of La3+, part of CeO(2 )crystals transformed from nanocubes to nanorods, inducing distinct effects on the catalytic activity. When the concentration of La3+ was lower than 10 %, the exposed facet in the catalyst was (200). After La(3+ )were further introduced, the facet degraded to (111). La3+ at low concentration would enhance activity by facilitating lattice oxygen delivery and inducing abundant surface oxygen species, especially O-, which were vital to surface sensitive soot oxidation. Nevertheless, excessive La3+ ions would inhibit CO2 desorption due to the generation of La2O2CO3, a strong alkali as a result of phase separation. Among all the catalysts, Ce0.95La0.05O delta showed the best catalytic performances for soot combustion, with T(50 )of 375 ?C.

Automated summary

In this study, facet controlled Ce1_xLaxO delta nanocomposites were constructed and used for soot abatement. The effects of crystal facets on heterogeneous catalysis were investigated. The results showed that the concentration of La3+ had a significant impact on the catalytic activity, with low concentrations enhancing the activity and excessive concentrations leading to undesirable effects.