Biomedical Engineering Reference
In-Depth Information
area [5, 8]. It is worth noting that the hydrogen uptake per unit
surface area of cobalt-doped CAs are higher than that measured for
the pure CA (~1.1 wt.%). CA-Co-I contains 1.3 wt.% H
and CA-Co-II
2
1.8 wt.% H
/g of surface area, respectively. The
results suggest that there exist interactions between metallic
particles and carbon surface which give rise to enhanced hydrogen
adsorption capacity. On the basis of our results, the flexibility of
chemistry synthesis approaches allows for the incorporation of metal
dopants into a porous carbon matrix to enhance hydrogen uptake in
Co-doped CA with respect to unit surface area or micropore volume.
However, whether the adsorption mechanism is due to surface
heterogeneity, to the interaction among adsorbed molecules, or to
the interaction between hydrogen molecules and metallic particles
is yet to be determined from our measurements. Research is now
in progress to clarify the role of metallic particles during hydrogen
adsorption, e.g., the effects of metal dopants on the heat of adsorption.
It is also noted that our group has recently experimentally shown
that particle size has an effect on the thermodynamic properties of
MgH
for every 500 m
2
2
nanoparticles [54]. This research will feed into our work on
doping CAs with metallic particles.
2
3.5
Conclusions and Outlook
CAs derived from resorcinol and furfural were prepared by a sol-gel
technique via ambient pressure drying, followed by carbonization
and activation under nitrogen and carbon dioxide gases, respectively.
In order to optimize the microstructure of CAs, base and acidic
catalysts were incorporated in the resorcinol-furfural precursors.
Both acetic acid and KOH can accelerate the gelation process,
because the activities of the precursors are increased in the presence
of acetic acid or potassium hydroxide. Moreover, both work not only
as a catalyst, but it is also hypothesized that they act as cross-linking
agents, which strengthens the formation of covalent bridges between
resorcinol rings. Furthermore, metal-doped CA was prepared by a
wet-layer coating method in order to modify the CAs microstructure
and its reactivity. CAs possess fast sorption kinetics that are favorable
in practical hydrogen storage applications. Such CA materials show
promise as media for gas storage, especially hydrogen due to the
material's high porosity, high surface area, and light specific weight.
