Hydrogen adsorption in nitrogen enriched ordered mesoporous carbons doped with nickel nanoparticles

Ordered mesoporous carbons were enriched with nitrogen, then loaded with nickel nanoparticles and the effects on hydrogen storage were investigated. Firstly, a comparative characterization was carried out using transmission electronic microscopy, X-ray diffraction, nitrogen adsorption isotherm and thermogravimetric analysis. It was shown that the nickel was interacting with the nitrogen functional groups on the surface of the carbon support and even led to the formation of particles of different sizes. Secondly, hydrogen storage was studied. Hydrogen adsorption by volumetric method at 77, 298 and 373 K and high pressures (3 MPa) exhibited two distinct behaviors. At 77 K, the textural properties are critical and the adsorption capacities decreased with the nickel loading. On the contrary, at ambient and higher temperatures, the contribution of nickel nanoparticles was positive and marked by increased amounts of hydrogen reversibly adsorbed. Furthermore, the electrosorption of hydrogen was examined. It consists of the electrolysis of water that causes the formation and the diffusion of hydrogen on the adsorbent surface. In that particular application, the combination of nickel doping and nitrogen enrichment was detrimental to the adsorption capacities. However, nickel doped on pure carbons enhanced the amount of hydrogen electrosorbed.

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► Nickel nanoparticles were impregnated on nitrogen-enriched mesoporous carbons.
► Nickel nanoparticles became larger with the nitrogen content of the carbon support.
► At 298 K, 0.5 wt.% of hydrogen were adsorbed by nickel-doped carbon nitrides.
► Nitrogen surface groups were detrimental to the electrosorption of hydrogen.