Feature-rich fundamental properties of hydrogen-adsorbed armchair graphene nanoribbons: insights from first-principles calculations†

Using first-principles calculations, we report on the notable structural, electronic, and magnetic properties of hydrogen-adsorbed 7-armchair graphene nanoribbons (7-AGNR) at various adatom concentrations and distributions. Key findings include optimal structural parameters, adsorption energies, one-dimensional electronic band structures, density of states (DOS), charge density distributions, charge density differences, and spin density distributions. Our results indicate that hydrogen atoms preferentially adsorb on the top sites of carbon atoms, with double-side adsorption being more stable than single-side adsorption. Even-hydrogenated 7-AGNR configurations behave as nonmagnetic semiconductors with varying bandgaps, while odd-hydrogenated configurations exhibit ferromagnetic behavior with different bandgaps. The number of unpaired hydrogen adatoms influences the magnetic moments of these configurations. Specifically, the magnetic moment can reach up to 7 μ_B for complete single-side hydrogenation, while all other odd-hydrogenated configurations generally display a magnetic moment of 1 μ_B. This behavior is attributed to the complex hybridization between hydrogen and carbon orbitals. This research highlights the potential of hydrogen-adsorbed 7-AGNR systems for applications in advanced electronics, optoelectronics, and spintronics.