DFT Study of Chemical Adsorption of NO<sub>2</sub> Gas on Graphene Nano Material

In the current study, the density function theory (DFT) is used to investigate the chemical adsorption strength of NO2 gas molecule. The relaxation structure, molecular orbital energy, energy gap and adsorption energy are calculated at ground state. The time dependent DFT (TD-DFT) used to simulate excitation provides UV-Visible spectrum. There was a perpendicular geometrical orientation of the gas molecule around the surface and an adsorption distance of 2.58 Å. The adsorption distance shows the chemical reaction between the gas molecule and the surface. The result of adsorption energy indicates that the gas molecule that closed to the surface has high interaction and it decreases gradually when gas molecule goes further from the graphene nano-ribbon surface. The UV-Visible measurement indicates that the system interaction with gas molecule has red shifting in electromagnetic radiation. The final result concludes that graphene nano-ribbon has high reactivity for NO2 gas molecule. The theoretical calculations provide the ability to design optical sensor which has useful applications in an environmental monitoring.