A novel candidate for hydrogen storage: Ca-decorated zigzag C3N nanotube

•Adsorption of hydrogen atom on Ca-decorated (8,0) C3NNT has been studied by spin-polarized DFT calculations.•Ca-decorated C3NNT has been proposed as a suitable candidate for hydrogen storage.•Clustering of the Ca atom on the nanotubes can be prevented by defect region.•Chemical nature of interaction between adsorbent and adsorbate is studied.•Interaction of Ca with C3NNTs and H2 molecules are explained be Dewar coordination and Kubas interaction, respectively.

In order to search high-capacity hydrogen storage media, first-principles calculations were performed. Ca-decorated on perfect and defective C3N nanotube as a new adsorbent for H2 molecules were studied. It was found that the Ca-decorated on defective nanotube can adsorb up to eight H2 molecules with the average binding energy of 0.11 eV/H2. Interaction of Ca atom with the nanotubes and H2 molecules are explained by Dewar coordination and Kubas interaction, respectively. Furthermore, the binding energy of the Ca atom on the defective nanotubes at least two times larger than the perfect one. Hence, clustering of the Ca atom on the nanotubes can be prevented by defect region.