Enhanced hydrogen storage in graphdiyne through compressive strain: Insights from density functional theory simulations

Hydrogen storage in solid-state materials can effectively make hydrogen-powered fuel cell vehicles possible in light-duty vehicles. Herein, we have explored the hydrogen storage performance of graphdiyne under 2 % compressive biaxial strain (G@2S). We have used first principles calculations to compare the interaction of hydrogen in pristine graphdiyne and G@2S. The hydrogen adsorption energy improved substantially in the presence of strain, and G@2S could load 6.942 wt% of hydrogen with an adsorption energy of -0.224 eV/H2. The application of strain altered the electronic structure of graphdiyne by reducing the bandgap, and a charge redistribution occurred between the atoms of G@2S. This induced polarization in the adsorbing hydrogen molecules thereby improving the adsorption energy towards hydrogen as compared to that in pristine graphdiyne. G@2S remained structurally stable at 300 K as verified via ab initio molecular dynamics simulations. The adsorbed hydrogen may be released by elevating temperatures to 290 K at 12 bars for hydrogen delivery. In summary, we find that strain engineering can be a promising strategy for improving the hydrogen storage performance of carbon nanomaterials like graphdiyne.