Ni-doped carbon xerogels for H2 storage

Activated carbon xerogels, with selected characteristics, were doped with Ni, using different methods, and tested for hydrogen storage. The results obtained show that the amount of nickel incorporated, the Ni-carbon interaction and the nickel particle size distribution depend more on the doping method used than on the textural properties of the carbon support. The amount of nickel incorporated by strong electrostatic adsorption is lower than that incorporated by dry impregnation. However, the strong electrostatic adsorption method produces Ni-doped carbon xerogels with a high Ni-carbon interaction and a narrower Ni particle size distribution. The influence of Ni on H₂ storage capacity depends on the operating conditions and the doping conditions used. Thus, at −196 °C and 40 bar, storage capacity seems to be mainly influenced by the textural properties of carbon support while, at 25 °C and 200 bar, the spillover effect plays a significant role, being the interaction between the support and Ni particles key factor in the storage process. The best Ni-doped carbon xerogels obtained in this work exhibit hydrogen storage capacities of 6 wt.% and 31.8 g l⁻¹ at −196 °C and 40 bar.