Strain effects on hydrogen storage in Ti decorated pyridinic N-doped graphene.

Strain-engineered adsorption of Ti on pyridinic nitrogen-doped graphene (PNG) and the hydrogen storage characteristics of Ti-decorated PNG are examined by using a first-principles approach using density functional theory (DFT) calculations. Under the strain from -5% to 5%, binding energy (Eb) of Ti on PNG was higher than cohesive energy of the Ti bulk. Thus, it is expected that Ti atoms prefer atomic dispersion in PNG to clustering in the applied strain range. For this Ti-PNG system, the Eb variation of the second and third adsorbed H2 molecule according to the strain was a large value of 0.217 and 0.254 eV, respectively. Therefore, strain-engineered Ti-decorated PNG is adaptable to diverse operation conditions of hydrogen storage systems for mobile applications. In addition, by applying compressive strain, this system can adsorb the fourth H2 molecule, suggesting that the compressive strain can be used to improve hydrogen storage capacity. Thus, it can be expected that strain-engineered Ti-decorated PNG can be considered to be a promising potential hydrogen storage medium.