Ability of transition metal and hetero atoms co-doped SWCNTs for hydrogen adsorption: A DFT study

The hydrogen adsorption capability of functionalized armchair single walled carbon nanotubes (SWCNTs) has been studied to analyze their candidature for hydrogen sensing and storage. Our proposed approach serves as a frame for assessing and prophesying the scope of Au/Ag/Cu/boron/nitrogen atoms doped/co-doped CNTs in the field of hydrogen energy. To corroborate the efficacy of our approach, we perform an ample investigation using armchair SWCNTs having chirality (5,5). Applying our criteria, we thoroughly screen Au/Ag/Cu/boron/nitrogen doped/co-doped in SWCNTs and analyze structural stability, electrical stability and thermo-dynamical stability of the substrates. Our results are based on the calculations of binding energy, bond distances, Bader's Topological Analysis, band gaps, electrophilicity, Density of states (DOS), Mulliken and Natural bond orbital (NBO) charge distribution, adsorption energies, adsorption enthalpy and Gibbs free energy of all the species by utilizing density functional theory (DFT). We found that Au-BCNT, Au-Ag-CNT and Au-Cu-CNT structures have good hydrogen sensing properties, whereas, Ag-NCNT shows better hydrogen storage among all studied species with an average adsorption energy of - 0.815eV/H2 and it can adsorb four hydrogen molecules at 298.15K temperature and 1atm pressure. The storage of H2 in Ag-NCNT is reversible at desorption temperature of 605K-172K.