Environmental Engineering Reference
In-Depth Information
2PSC
SiO
2
nanoparticles
opal
Impregnation
with RF resin
Carbonization
Removal
SiO
2
with HF
Removal of SiO
2
with HF
Carbonization
1PSC
SCHEME 2.5
Formation of nanoporous carbon by hard templating of RF resin using SiO
2
nanoparticles.
FIGURE 2.4
Scanning electron micrograph of a porous carbon (1PSC) synthesized using an opal of SiO
2
nanoparticles (400-nm
diameter) as hard template. Cut is made using FIB of Ga ions. Lateral dimension is 5 microns.
2.2.1.5 Self-Assembly of Porous Carbon Microparticles to
Produce Hierarchical Carbon Layers
Porous carbon microparticles can be fabricated by grinding the solid and sieving the
particles [109] (Figure 2.5a), or by synthesizing inside water pools of microemulsion [110]
(Figure 2.5b). Carbon nanoparticles can be fabricated by controlling the nucleation of the
resin nanoparticles in solution [111] (Figure 2.5c).
The porous particles can be assembled by sequential dipping of a surface functional-
ized with charged groups (e.g.,
−
−
SO
3
groups linked to the glass through silane chemis-
try [112]) in dispersions of charged particles and polyelectrolytes of opposite charge [113].
The technique is usually known as layer by layer (LbL) and was pioneered by G. Decher
[114]. However, in our case, optical microscopy of the surface shows an increasing two-
dimensional coverage of the surface, instead of an LbL growth (Figure 2.6).
