Ni-doped activated carbon nanofibers for storing hydrogen at ambient temperature: Experiments and computations

Activated carbon nanofibers (ACNF*) prepared by carbonization and chemical activation of polyacrylonitrile (PAN)-polyvinylpyrrolidone (PVP) electrospun nanofibers and doped with 5-20 wt% Ni are proposed for hydrogen adsorption at 25 degrees C. The best hydrogen adsorption capacities up to 2.12 wt% H-2 (p(H-2) = 100 bar) together with cycling stability upon 10 ad/desorption cycles with average capacity of 1.17 wt% H-2 (p(H-2) = 50 bar) are obtained from 5 wt% Ni-doped ACNF*. Excellent ad/desorption and reversibility are benefited from small particle sizes (5-10 nm) and uniform distribution of Ni nanoparticles. The latter is due to not only suitable Ni loading content (5 wt%) but also strong interaction between Ni nanoparticles and N atoms in ACNF*, confirmed by both experiments and first-principles computations. Both experiments and computations indicate that hydrogen adsorption mechanisms are not only chemisorption of adsorbed hydrogen atoms onto Ni nanoparticles but also physisorption and spillover of hydrogen.

Automated summary

The study introduces activated carbon nanofibers doped with 5-20 wt% Ni for hydrogen adsorption, demonstrating excellent cycling stability and reversibility, attributed to the uniform distribution and small particle sizes of the Ni nanoparticles.