PROFESSOR K.Y. CHAN
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Hollow Core-Mesoporous Shell (HCMS) Hierarchical Carbon
Three-dimensional (3D) hierarchical porous carbons have been proposed to yield good specific energy density and power density. It is desirable to structure the porous carbon with pores of multiple length scales and with micropores/mesopores interconnected by larger pores . An optimum structure is believed to possess high surface smaller pores interconnected with larger sets of pores with efficient ion diffusion pathways.
SEM Images of A Structure with 330 nm Core Diameter and 150 nm Thick Shell Thickness
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Pore Size Distributions of The Family of HCMS Structures All Having Sharp Peaks at 3.9 nm Dia
 Hierarchical Carbon/hcms1.png)
A hierarchical porous carbon structure synthesized from an assembly of macrospheres a few hundred nanometres in size with variable mesoporous shell thickness. This simple structure has pores at several length scales distributed over the hollow cores, mesoporous shell, and the interstitial regions. The ¡§hollow core¡Vmesoporous shell¡¨ carbon structure can be template-synthesized from solid silica spheres each coated with a mesoporous silica shell. The three structural parameters, the mesopore diameter(dp), mesoporous shell thickness(S), and macropore diameter(C) can be separately tuned and controlled in the synthesis. This provides a very useful model structure for studying ionic transport and surface limited electrochemical reactions in relation to porosities at different length scales.
TEM images of (a)solid core, shell thickness of (b)50 nm, (c)80 nm and (d)150 nm
 Hierarchical Carbon/hcms3.gif)