Lithium-Decorated C26 Fullerene in DFT Investigation: Tuning Electronic Structures for Enhanced Hydrogen Storage

Hydrogen energy holds immense potential to address the global energy crisis and environmental challenges. However, its large-scale application is severely hindered by the lack of efficient hydrogen storage materials. This study systematically investigates the H2 adsorption properties of intrinsic C26 fullerene and Li-decorated C26 fullerene using density functional theory (DFT) calculations. The results reveal that Li atoms preferentially bind to the H5-5 site of C26, driven by significant electron transfer (0.90 |e|) from Li to C26. This electron redistribution modulates the electronic structure of C26, as evidenced by projected density of states (PDOS) analysis, where the p orbitals of C atoms near the Fermi level undergo hybridization with Li orbitals, enhancing the electrostatic environment for H2 adsorption. For Li-decorated C26, the average adsorption energy and consecutive adsorption energy decrease as more H2 molecules are adsorbed, indicating a gradual weakening of adsorption strength and signifying a saturation limit of three H2 molecules. Charge density difference and PDOS analyses further demonstrate that H2 adsorption induces synergistic electron transfer from both Li (0.89 |e| loss) and H2 (0.01 |e| loss) to C26 (0.90 |e| gain), with orbital hybridization between H s orbitals, C p orbitals, and Li orbitals stabilizing the adsorbed system. This study aimed to provide a comprehensive understanding of the microscopic mechanism underlying Li-enhanced H2 adsorption on C26 fullerene and offer insights into the rational design of metal-decorated fullerene-based systems for efficient hydrogen storage.