Synergistic H ₂ ─CH ₄ Co‐Adsorption on Scandium‐Decorated [5]Cycloparaphenylene Nanohoops for Gas Storage Application

ABSTRACT

This work presents computational insights into the cooperative adsorption and storage of hydrogen and methane gas in scandium (Sc) decorated [5]cycloparaphenylene ([5]CPP) nanohoops using first principles calculations supplemented with Grimme's dispersion correction (DFT+D3). The Sc atoms were functionalized over the [5]CPP molecule with an average binding energy of 1.53 eV. A single Sc atom can store up to five hydrogen molecules and four methane molecules in quasi‐molecular form. The calculated average adsorption energies vary between 0.21 and 0.353 eV/H ₂ and 0.263 and 0.243 eV/CH ₄ . At low temperature and pressure, the system exhibits a maximum gravimetric capacity of 7.68 wt% and 34.64 wt% for hydrogen and methane, respectively. The calculated van't Hoff temperature for hydrogen molecules shows a minimum at 296.9 K under 1 atm pressure. The desorption of H ₂ molecules from the [5]CPP starts at around 300 K, and complete desorption occurs at more than 500 K. The host system is thermally stable, as evidenced by the atom‐centered density matrix propagation molecular dynamics (ADMP‐MD) simulations at different temperatures. Our calculations predict that Sc‐functionalized [5]CPP can be a promising catalyst for efficient H ₂ and CH ₄ storage, providing useful insights for its applications in sustainable energy.