Studying the electronic properties of SiO₂/GO/Pb₃O₄/Bi₂O₃ composite structure

This study investigates the electronic properties of a proposed composite structure consisting of SiO₂, Pb₃O₄, Bi₂O₃, and graphene oxide (GO) for glutamic acid (Glu) biosensing applications in aqueous media. Using Density Functional Theory (DFT) at B3LYP functional and SDD basis set, we examine the reactivity and electronic properties of the combination of these structures under weak and complex interaction scenarios with Glu. The study focuses on studying total dipole moments (TDM), HOMO/LUMO bandgaps, molecular electrostatic potential (MEP) maps, reactivity descriptors, and the density of states (DOS) for the proposed model molecules. The calculated TDMs and HOMO/LUMO bandgap energies highlight the highly reactive nature of the 3SiO₂/GO/Pb₃O₄/Bi₂O₃ "complex" structure toward the surrounding species. This is because it has the highest TDM (up to 35.1 Debye) and the lowest bandgap energy (decline significantly to 0.158 eV). The MEP maps for the interaction between 3SiO₂/GO/Pb₃O₄/Bi₂O₃ and Glu under the two proposed scenarios display markedly different MEP profiles, underscoring the substantial impact of the interaction type. Additionally, the interaction between 3SiO₂/GO/Pb₃O₄/Bi₂O₃ "complex" structure and Glu exhibits the highest ionization potential, electron affinity, and electronegativity. The plotted DOS curves of the interaction between the proposed composite structure (both weak and complex forms) and the target analyte reveal that the unoccupied states begin to emerge slightly below - 4.0 eV and - 5.0 eV, then extend towards 0.0 eV, indicating potential excitation energies for electrons. These findings boost the potential of the proposed 3SiO₂/GO/Pb₃O₄/Bi₂O₃ structure as a promising candidate for tailoring novel electrode materials for Glu biosensing applications, thereby advancing the development of effective biosensors.