Hydrogen storage on silicon, carbon, and silicon carbide nanotubes: A combined quantum mechanics and grand canonical Monte Carlo simulation study

• Published in: International journal of hydrogen energy Vol. 39; no. 4; pp. 1719 - 1731
• Main Authors: Mahdizadeh, S.J., Goharshadi, E.K.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 22-01-2014; Elsevier
• Subjects: Ab initio; Alternative fuels. Production and utilization; Applied sciences; Arrays; CNT; Computer simulation; Energy; Exact sciences and technology; Fuels; GCMC simulation; Hydrogen; Hydrogen storage; Mathematical models; Monte Carlo methods; Nanotubes; Quantum mechanics; SiCNT; Silicon carbide; SiNT; CNT; GCMC simulation; SiCNT; Hydrogen storage; Ab initio; SiNT; Monte Carlo method; Hydrogen; Nanotube; Silicon
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.11.037

Grand canonical Monte Carlo (GCMC) simulation combined with ab initio quantum mechanics calculations were employed to study hydrogen storage in homogeneous armchair open-ended single walled silicon nanotubes (SWSiNTs), single walled carbon nanotubes (SWCNTs), and single walled silicon carbide nanotubes (SWSiCNTs) in triangular arrays. Two different groups of nanotubes were studied: the first were (12,12) SiNTs, (19,19) CNTs, and (15,15) SiCNTs and the second were (7,7) SiNTs, (11,11) CNTs, and (9,9) SiCNTs with the diameters of ∼26 and ∼15 Å for the first and second groups, respectively. The simulations were carried out for different thermodynamic states. The potential energy functions (PEFs) were calculated using ab initio quantum mechanics and then fitted with (12,6) Lennard-Jones (LJ) potential model as a bridge between first principles calculations and GCMC simulations. The absolute, excess, and delivery adsorption isotherms of hydrogen were calculated for two groups of nanotubes. The isosteric heat of adsorption and the radial distribution functions (RDFs) for the adsorbed molecules on different nanotubes were also computed. Different isotherms were fitted with the simulation adsorption data and the model parameters were correlated. According to the results, the hydrogen uptake values in (19,19) CNT array exceeded the US DOE (Department of Energy) target of 6.0 wt% (FY 2010) at 77 K and 1.0 and 2.0 MPa for absolute and excess uptakes, respectively. The results also show that SiNTs and SiCNTs are not more useful materials compared with corresponding CNTs for hydrogen storage.
•Hydrogen storage on SiNTs, CNTs, and SiCNTs was modeled.•Hydrogen storage capacity of CNTs is greater than those of SiNTs and SiCNTs.•DOE target for hydrogen storage is accessible just using CNTs.•Our results challenge the previous studies in hydrogen storage on SiNTs and SiCNTs.