There are numerous numbers of porous materials available in literature. However, carbon nanotubes are chosen for this study. What is the reason for it? If we store hydrogen in it, how to deliver it? Whether with difference in pressure?
There are lots of reasons.
1. the hydrogen capacity (weight percent) : the adsorbent materials should have low weight for high wt%
2. the hydrogen gas should not dissociate into atomic species : physissorption, low temperauture condistion, easy reversible reaction
3. The adsorbent must consitute with abundant atomic species ( carbon is the best cadidate atom)
4. porosity
5. Easy tuning : The CNT can be easily tuned by various chemical reaction
Hope this help
There are lots of reasons.
1. the hydrogen capacity (weight percent) : the adsorbent materials should have low weight for high wt%
2. the hydrogen gas should not dissociate into atomic species : physissorption, low temperauture condistion, easy reversible reaction
3. The adsorbent must consitute with abundant atomic species ( carbon is the best cadidate atom)
4. porosity
5. Easy tuning : The CNT can be easily tuned by various chemical reaction
Hope this help
It was also studied through low temperature calorimetry and adsorption isotherms to probe the phases of physisorbed layer of gases that are quasi one or two dimensional. Gases such as hydrogen and helium are 'quantum' gases, Neon falls in the transition between classical and quantum behavior.
Adsorption on carbon nanotubes provides a good platform to study the sub monolayer film ( one or two dimensional adlayer) , and mono and multiple layers of adatoms.
Both Hydrogen and Carbon are hydrophobic. It is easier for physisorption. However the silica and zeolites are moderate to high hydrophilic. So Hydrogen adsorption is less or not possible. This may be a reason for its selection.
I agree, one would want stronger adatom-adatom interaction compared to the adatom substrate interaction. Our interest was to study the fundamentals of the adlayer and not necessarily determine suitability of a material for hydrogen storage.. Also the gases physisorbed on the grooves (D2, Ne etc) on the carbon nanotubes have been studied using neutron scattering. Bundles of nanotubes provide a long enough chain of adatom to be probed. .
CNTs have been investigated for H2 storage studies, just as they have also been investigated for a lot of things ! But for H2 storage as for many other applications, CNTs are not the best materials ever. As far as H2 storage is concerned, activated carbons are by far much better (see papers in my RG profile). But many studies have been done since Dillon et al. reported outstanding storage capacities some years ago. But this was an artefact. It took many additional studies to confirm that CNTs had in fact very disappointing storage capacities.
Alain
Hi Alain,
Would you point me to the specific publication where you found hydrogen storage in activated carbon, please? We had studied using activated carbon as a grinding aid along with Mg and Mg-based alloys and found improved kinetics and interesting changes to the morphology of the ground Mg based on amount of activated carbon.
Yes, carbon nanotubes are popular, but other porous materials are also widely investigated for hydrogen storage.
First of all, not only nanotubes, but other carbon materials, like activated carbons, templated carbons and fullerenes are under research.
Then, zeolites, metal-organic frameworks, microporous polymers, porous hydrides are also investigated.
So, there are different applications of porous materials for the hydrogen storage.
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