B-substituted nanoporous carbons for hydrogen adsorption.
Résumé
Hydrogen is considered to be the preferred successor to gasoline due to its clean combustion.
However, efficient and save storage of hydrogen remains the bottle-neck and one of the main challenges in hydrogen-based
technologies. In the past we have justified [1] the necessary conditions (materials physical properties) the hydrogen
adsorbents MUST simultaneously fulfilled to be used in mobile applications: it must exhibit the specific surface at least of
the order of 5000–7000 m2/g, have the average binding energy above 10 kJ/mol, and the density above 0.6 kg/m3. This set
of parameters put so strict constrains on possible solutions that such systems are neither yet known nor seem easy to
synthesize.
Here we explored the possibility to prepare boron-substituted nanoporous carbons, cheap, light and save material that was
supposed [2,3] to reversibly store hydrogen by physisorption at room temperatures and moderated pressure (< 120 bar). We
showed that electric arc discharge between graphite electrodes may be optimized to produce graphitized structures with a
variety of graphene fragment sizes, forms, and interconnections between them. It also allows to introduce boron heteroatom
into graphite-like structure. The as-synthetized material shows the hydrogen binding energy twice as high as unsubstituted
carbons, but requires post-treatment (activation) as the its surface is low (~200 m2/g).