First principles studies on hydrogen storage in single-walled carbon nanotube functionalized with TiO2

• Functionalizing SWCNTs with TiO2 for hydrogenation is a new theoretical attempt.
• Clustering of functional molecules on CNT is not observed.
• A maximum storage capacity of 3.64 wt% is obtained.
• The corresponding desorption temperature is 332 K.
• Functionalization and hydrogenation did not affect the electronic nature of the CNT.

In this first principles study, hydrogen storage capacity of armchair single-walled carbon nanotube (10, 10) functionalized with TiO2 has been investigated. The functionalized TiO2 molecules are found to be chemisorbed on CNT (10, 10) with the binding energy of 3.54 eV. The functionalized CNT binds up to six hydrogen molecules. The first hydrogen adsorption is dissociative with the binding energy of 1.51 eV and the further adsorbed hydrogen are weakly chemisorbed on the functionalized system with the elongated bond length of hydrogen. The storage capacity of functionalized SWCNT, desorption temperature and binding energy of hydrogen molecules are evaluated. The system exhibits a maximum storage capacity of 3.64 wt%. The band structure, density of states (DOS) and partial density of states (PDOS) are calculated for the functionalized and hydrogenated SWCNTs. DOS studies reveal that, functionalization and hydrogenation does not affect the metallic nature of CNT.