Chiang Chang-Yang, Zhou Wuzong
EaStChem, School of Chemistry, University of St Andrews Fife KY16 9ST UK
RSC Adv. 2021 Sep 1;11(47):29108-29114. doi: 10.1039/d1ra04996h.
Formation of Mn Co O yolk-shell microspheres a solvothermal reaction of hydrated cobalt and manganese nitrates in ethanol is investigated. Spinel nanocrystals of cobalt oxide or cobalt-rich ternary oxide preferentially develop in the system, while manganese-rich hydroxide form Mn(OH)-type nanosheets. Instead of continuing to grow individually, the nanocrystallites and nanosheets aggregate into large microspheres due to their strong inter-particle interaction. When the proportion of Mn-rich nanosheets is high, therefore the overall density is low, dehydration of hydroxide nanosheets and a surface re-crystallisation lead to formation of a dense and rigid shell, which is separated from a solid or hollow core a further Ostwald ripening process. The proposed formation mechanism of the yolk-shell structures based on electron microscopic studies would help us to develop yolk-shell structure based multifunctional materials.
研究了通过水合钴和锰硝酸盐在乙醇中的溶剂热反应形成Mn Co O核壳微球的过程。氧化钴或富钴三元氧化物的尖晶石纳米晶体在该体系中优先形成，而富锰氢氧化物形成Mn(OH)型纳米片。由于它们强烈的颗粒间相互作用，纳米微晶和纳米片不是继续单独生长，而是聚集成大的微球。因此，当富锰纳米片的比例较高且整体密度较低时，氢氧化物纳米片的脱水和表面再结晶导致形成致密而刚性的壳，该壳与实心或空心核分离，这是一个进一步的奥斯特瓦尔德熟化过程。基于电子显微镜研究提出的核壳结构形成机制将有助于我们开发基于核壳结构的多功能材料。
