Light Transition Metal Functionalized ψ‐Graphene as Promising Hydrogen Storage Architecture
Naseer H. Kadhim, Abbas H Abo Nasria, Khidhir Alhameedi, Tanveer Hussain, Heider A. Abdulhussein
Abstract
Developing effective methods and materials for hydrogen (H 2 ) storage in hydrogen fuel cell vehicles is essential to reduce reliance on fossil fuels in the transportation sector. Carbon‐based materials have been proposed as promising candidates for H 2 storage. In this article, van der Waals‐corrected density functional theory calculations are employed to explore the potential of ψ‐graphene monolayers doped with transition metals (Sc, Ti, and V) as promising H 2 storage materials. Metal dopants strongly bind with ψ‐graphene with binding energies of 4.38, 4.11, and 2.44 eV for Sc, Ti, and V, respectively. Additionally, the diffusion energy barriers of (0.5, 0.51, and 0.24 eV) for Sc, Ti, and V, respectively, on the ψ‐graphene surface significantly reduce the calculated metal agglomeration probability when Sc, Ti, and V are displaced from the Hp site to the Ha site. Metal decorated ψ‐graphene can bind up to six H 2 molecules, with average adsorption energies of 0.31, 0.37, and 0.41 eV per H 2 molecule for Sc, Ti, and V, respectively. The calculated H 2 storage capacities are 5.97%, 5.89%, and 5.80% for decorated ψ‐graphene systems with Sc, Ti, and V, respectively. These calculated properties align well with the U.S. Department of Energy's criteria for reversible H 2 storage in fuel cell vehicles. Thermodynamic analysis indicates that Sc@ψ‐graphene and Ti@ψ‐graphene offer the most favorable hydrogen storage performance under realistic operating conditions (30 atm and 25 °C for adsorption; 3 atm and 100 °C for desorption). AIMD simulations conducted at 400 K demonstrate the excellent thermal stability of X@ψ‐graphene (X = Sc, Ti, V) complexes, even at elevated doping concentrations. Throughout the 5 ps simulation, regulated by a Nosé–Hoover thermostat, the systems preserved their structural integrity, highlighting their resilience to thermal fluctuations and suitability for high‐temperature applications. Consequently, ψ‐graphene doped with Sc, Ti, or V emerges as an exceptional material for reversible H 2 storage.