Adsorption of carbon monoxide on the pristine, B- and Al-doped C3N nanosheets

The potential application of the intrinsic and extrinsic (8,0) zigzag single-walled C3N nansheets as chemical sensor for CO molecules has been investigated using density functional theory calculations. The calculation shows that the pristine sheet is a semiconductor with a HOMO-LUMO gap (Eg) of about 2.19 eV. The pristine and B-doped sheets can weakly adsorb a CO molecule with the adsorption energies of -4.8 and -4.6 kcal mol(-1), and their electronic properties are not sensitive to this molecule. By replacing a C atom with an Al atom, localized impurity states are induced under the conduction level of the sheet. The binding interaction between the CO molecule and the Al-doped sheet becomes much stronger (Ead = -17.8 kcal mol(-1)). After the adsorption of CO on the Al-dope sheet, the Eg of the sheet is significantly decreased from 1.07 to 0.73 eV. This leads to a sizable increase in the resistance of the tube. Thus, the Al-doped sheet can show the presence of CO molecules by an electronic signal because of the change in its resistance and conductivity.