화학공학소재연구정보센터
Chemical Engineering Science, Vol.66, No.10, 2157-2163, 2011
Engineered morphologies of layered double hydroxide nanoarchitectured shell microspheres and their calcined products
(CoFeFeIII)-Fe-II-layered double hydroxide (LDH) hollow spheres with two distinctly different hierarchical morphologies-flower-like and raspberry-like, involving edge-on and face-on oriented LDH platelets as building blocks, respectively-can be fabricated by tuning the rate of addition of NaOH solution in a coprecipitation process with sulfonated polystyrene spheres as a template. Ex situ pH-dependent microscopic observations of the formation of the flower-like LDH shells shows the details of non-classic nucleation and growth underlying the edge-on orientation. After calcination, the resulting CoFe2O4 materials retain the hierarchical morphology of the corresponding LDH precursor. The hollow CoFe2O4 spheres with raspberry-like morphology exhibit magnetic properties comparable to a reference material obtained by calcination of a conventional LDH powder precursor. Similar materials with tunable magnetic properties can be prepared by virtue of the flexibility in LDH layer composition. The (CoFeFeIII)-Fe-II-LDH spheres with a raspberry-like morphology may be also be prepared by using a scalable procedure involving separate ultra-rapid nucleation and aging steps in a modified colloid mill reactor. The results reported here may open up the possibility of producing shell structures with controllable morphologies and properties on a large scale. (C) 2011 Elsevier Ltd. All rights reserved.