The adsorption of CO molecule on pristine and X= (Mn and Tc) doped graphene sheets (G) in the presence and absence of applied static electric fields (SEF, 0.010-z, 0.011-z, 0.012-z, 0.013-z, 0.014-z and 0.015-z) has been investigated using density functional theory (DFT). The changes in geometric and electronic structures of all adsorption configurations were analysed to characterise the sensitivity of G towards CO molecules. Our calculated results showed that with doping Mn and Tc atoms and in the presence of SEF field, the adsorption of CO on the surface on G increased and adsorption process was chemisorptions type. The partial electronic density of states (PDOS) indicated that the doping Mn and Tc atoms and SEF combination effect increased the interaction and hybridisation between 2p orbitals of CO molecule with 2p orbitals carbon atoms of the G. According to the obtained results, due to applying X-doped and SEF, the primary symmetry of G changes significantly from the original state and thereby the chemical activity of G towards CO molecules enhanced. The results showed that Mn and Tc-doped with SEF field might be a good strategy for enhancing the CO adsorption capability on the surface of G and improving their sensor applicability.
