Modification of carbon nanotube surface with copper oxide for application in gas-sensitive systems: a theoretical study

DFT calculations for adsorption of copper oxide on the surface of carbon nanotubes of type (6,6) have been carried out in this work. The most energetically favorable location of copper oxide atom relative to CNTs was determined. The charge distribution in the optimized complexes is described and the electronic properties of the CNT-CuO system are determined. It is revealed that CuO is adsorbed on the surface of armchair-type CNTs by the mechanism of chemical sorption and as a result, a strong chemical bond is formed. The magnitude of the energy gap increases in the case of adsorption of CuO molecule by oxygen atom on the CNT surface (6,6) in the position above the carbon atom. The adsorption of CuO causes charge redistribution and the electron density shifts from oxygen atom to carbon atoms of CNTs. The gas-sensitive properties of CNT-CuO towards methane and carbon dioxide were also investigated. Physical sorption of methane and carbon dioxide was observed. Such adsorption processes cause changes in the electronic and charge properties of the considered composite. Thus, it can be concluded that CNT-CuO composite can be a candidate for the creation of highly efficient gas sensors of methane and carbon dioxide on their basis.