Controlling electronic and optoelectronic behavior of graphene ionic liquids based metal salt amalgamation: A DFT Perspective

초록

Controlling the electronic and optoelectronic properties of graphene-based hybrid systems remains a key challenge in the design of advanced functional materials for energy applications. In particular, understanding how metal salts interact with graphene in the presence of ionic liquids (ILs) is crucial for tuning interfacial behavior, ionic conductivity and device performance. In this study, we investigate how metal atom adsorption at a graphene-ionic liquid interface modifies the structural, electronic and optical properties of the system. Using density functional theory (DFT), we systematically elucidate the binding behavior of Li, Na, K, Mg and Al atoms with (i) IL [MMIm](+)[AlCl4](-) (ii) pristine graphene and (iii) IL-functionalized graphene. Binding affinities in the gas phase correlate with the charge-to-radius ratio of the metal atoms, with Mg and Al exhibiting the strongest interactions through short M & centerdot;& centerdot;& centerdot;Cl bonds and notable electron redistribution. The introduction of the IL at the graphene interface enhances metal adsorption by up to similar to 1.2 eV, particularly for Li and Al, due to strengthened electrostatic interactions and favorable charge transfer. Electronic structure analysis, including projected density of states and band structures, reveals that the interactions are predominantly electrostatic and non-covalent, while preserving the Dirac cone characteristics of graphene. Optical calculations further show an enhanced dielectric response of similar to 4 eV and anisotropic electronic behavior modulated by plasma frequency components in both parallel and perpendicular to the graphene plane. These findings demonstrate a synergistic effect between IL functionalization and metal salt adsorption in tailoring graphene's electronic and optoelectronic properties, providing insights for designing next-generation optoelectronic and high energy-harvesting materials.

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