First-principles investigation of hydrogen storage in pristine AlN nanosheets with a biphenylene framework

Abstract One of the most important aspects of the energy transition towards sustainable development is the efficient storage of hydrogen, for which a diverse range of materials is being studied. Here, we investigated the structural and electronic characteristics of biphenylene aluminum nitride (BP-AlN) nanosheet using density functional theory (DFT) calculations. Potential hydrogen adsorption sites were investigated and evaluated based on thermodynamic viability, as determined by the adsorption energy at these locations. The interatomic interactions and charge transfer were characterized based on Bader charges and density of states (DOS) at various concentrations of adsorbed hydrogen. The interatomic interactions were further determined using the quantum theory of atoms-in-molecules (QTAIM), which involves calculating various topological descriptors at the bond critical points. The detailed investigation of hydrogen storage in the BP-AlN nanosheet shows that the material exhibits high gravimetric and volumetric hydrogen storage capacities of 8.96 wt% and 105.41 g/L, respectively, exceeding the U.S. Department of Energy (US DOE) long-term targets of 6.5 wt% and 50 g/L. In addition, the calculated average hydrogen binding affinities range from − 0.24 to -0.29 eV/H 2 . The efficiency of the hydrogen uptake-release cycle was evaluated by calculating the hydrogen desorption temperatures at various hydrogen concentrations, which suggests that the material can be utilized in room-temperature hydrogen storage devices. This makes BP-AlN nanosheet a viable option for safe, effective, and energy-efficient onboard hydrogen storage for light-duty hydrogen-powered vehicles.