Construction of a hollow structure in La0.9K0.1CoO3−δ nanofibers via grain size control by Sr substitution with an enhanced catalytic performance for soot removal

Perovskite-type La0.9K0.1CoO3-delta nanofibers were fabricated successfully using an electrospinning technique with calcination, based on the successful preparation of LaCoO3 nanofibers considering the enhancement in the activity by K+, which could facilitate oxygen species transfer and accelerate redox circulation. Furthermore, a hollow structure could provide more pathways for soot transportation and transmission of reaction gas (O-2 and NO), improving the contact efficiency of soot-catalyst-gas and contributing to the enhancement in catalytic activity. However, the grain size increasing in the calcination has a great influence on the formation of the hollow structure. Thence, the introduction of some Sr2+ in La0.9K0.1CoO3-delta nanofibers was taken into consideration to construct the hollow structure, by the inhibition of grain growth during heat treatment at a high temperature. Meanwhile, the Sr2+ doping could further promote the catalytic activity. After comparison, an appropriate amount of Sr2+ was introduced and the perovskite-type La0.63Sr0.27K0.1CoO3-delta nanotubes were successfully prepared in this work as a result. Besides, some related catalysts were also prepared for comparison with the same method. These as-prepared catalysts were investigated by a series of characterization techniques. The activity evaluation of the catalysts was carried out through temperature programmed oxidation in 5% O-2 and 2000 ppm NO, as well as in the presence of 6% H2O. According to the activity data, La0.63Sr0.27K0.1CoO3-delta nanotubes could be recognized as a high-performance catalyst for soot oxidation.