Formation mechanism of yolk--shell LaMnO₃ microspheres prepared by P123-template and oxidation of NO

Abstract

The yolk–shell LaMnO₃ perovskite microspheres were fabricated by a novel, simple and mild soft template approach. A series of template-P123 concentrations (0–6.12 mmol∙L⁻¹) were employed to optimize the most complete spheres. When the concentration of P123 is 3.0 mmol·L⁻¹, the obtained yolk–shell microspheres with a diameter of 200–700 nm were constructed by nanoparticles. The possible formation mechanism of the yolk–shell microspheres was revealed step by step via XRD, SEM, TEM, EDS and HRTEM. Molecules of P123 were suitably mixed with solvents for double shelled vesicles through self-assembly, which interacted with metal complexes to form P123–metal vesicles. After the removal of P123 and citric acid by calcination at 700 °C, the yolk–shell LaMnO₃ microspheres with through-channels were obtained. Through-channels on the surface were due to citric acid and the solid core was attributed to the shrink of inner vesicles. Prepared yolk–shell microsphere samples possessed a larger surface area and a higher maximum NO conversion value of 78% at 314 °C for NO oxidation, compared with samples without the yolk–shell structure.

Keywords

perovskite / yolk--shell / microspheres / NO oxidation

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant No. 21607086), the Public Projects of Zhejiang Province (Grant No. 2016C33024), the Scientific and Technological Program of Ningbo City (Grant Nos. 2016C51025, 2017C50031 and 2017A610061), and the K. C. Wong Magna Fund from Ningbo University.

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