▎ 摘　　要

Density Function Theory (DFT) calculation was used to find out ground and excitation states for graphene ribbons, types of adsorption, energy gap, maximum wave length and optical band gap. Adsorption energy showed that CO2 gas molecule had chemical adsorption in distance 1 and 1.5 Angstrom. CO2 gas molecule appeared to have physical adsorption in distance 2 and 2.5 Angstrom. Adsorption energy decreased when the distance between surface and gas molecule increased. Resulting from chemical adsorption energy gap, there was a change in distance 1 and 1.5 Angstrom due to the attraction of gas molecule towards surface. Excitation energy for Nano system in samples 1 and 4 shifted to low wavelength (blue shift), changing from 1018 to 993 nm and 718 nm on series. Other sample had red shift and the energy gap became open. The result showed that graphene ribbon sensed carbon dioxide gas (CO2).