Comparing hydrogen sorption in different Pd-doped pristine and surface-modified nanoporous carbons

Three types of nanoporous carbons (a molecular sieve, an ordered mesoporous carbon and a carbon aerogel) with distinctively different porous properties were subjected to surface modification through wet oxidation and subsequent metal doping with Pd nanoparticles. The H2 sorption performance of the carbons and their doped analogues was examined at 298 K up to 20 bar. The introduction of different oxygen containing groups in the three carbons enhances the amount of sorbed hydrogen, while the rather complex mechanism of sorption seems to be positively influenced by the small size of the pores and the surface chemistry. It was shown that in all cases a synergistic effect between the metal and the oxidized carbon takes place, leading to enhanced hydrogen sorption through reversible processes, which however is not sufficient to meet the demanding targets for practical applications.