Adsorption of formaldehyde molecule on Al-doped vacancy-defected single-walled carbon nanotubes: A theoretical study

The interactions between formaldehyde (H2CO) and modified (8, 0) single-walled carbon nanotubes, including Al doping, vacancies, and a combination of these two, were investigated using the density functional theory (DFT) method. It was found that H2CO adsorption on vacancy-defected CNTs had relatively higher adsorption energy and shorter binding distance compared with the perfect one. Furthermore, there existed a strong chemical adsorption between H2CO molecule and Al-doped defected CNTs, which exhibited more active interaction and larger net charge transfer than that of defected CNTs without Al-doped. The spin polarized electronic density of states (PDOS) of the adsorption systems suggested that the enhancement of adsorption was due to the hybridization between Al atom and the C atoms at the vacant sites. Therefore, Al-doped vacancy-defected CNTs could be expected to be novel chemical sensors for detecting H2CO gas.