Application of Cs/GO/TiO2 as Gas Sensor
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Chitosan a biodegradable, cheap polymer is a good choice for gas sensors. In this study, chitosan (Cs) was modified with graphene oxide (GO) and titanium dioxide (TiO 2 ), and its electronic properties were calculated using density functional theory (DFT) at B3LYP/LANL2DZ level. The calculated physical parameters includes total dipole moment (TDM), HOMO/LUMO energy gap (ΔE), global reactivity descriptors and density of states (DOS) and mapping the electrostatic potential (MESP). Results indicated Cs had significant modification such as enhanced ΔE from 6.908 to 2.197 eV and TDM from 5.884 to 14.432 Debye, global reactivity revealed enhanced reactivity with increased absolute softness and high electrophicility index. DOS show more available states and more localized HOMO/LUMO orbitals all enhance charge transfer. MESP shows reactivity and active sites for the interaction with its surrounding. The nanocomposite Cs/GO/TiO 2 is supposed to interact with three different gases; H 2 O, CO 2 , and CH 4 . The results exhibited changes in the ΔE and TDM, with Cs/GO/TiO 2 /CO 2 have the most pronounced changes. Partial density of states PDOS plots exhibited Ti atoms contribution in HOMO orbitals and LUMO with Cs/GO/TiO 2 /CO 2 having the most changes in its energy states. Adsorption energy E a was calculated and showed selectivity for CO 2 gas with − 0.104 eV indicating spontaneous interaction. Quantum theory of atoms in molecules confirmed the weak interaction with gases molecules and the enhanced stability via hydrogen bonding. The Cs/GO/TiO 2 nanocomposite was synthesized and FT-IR spectroscopy were conducted and compared with calculated IR to verify the models.
