The hybrid of Pd and SWCNT (Pd loaded on SWCNT) as an efficient sensor for the formaldehyde molecule detection: A DFT study

The potential sensor of pristine and Pd-loaded on the surface of single-walled carbon nanotube for formaldehyde (CH2O) molecule is investigated in this paper using the density functional theory (DFT) method. The Pd-loaded single-walled carbon nanotube (Pd/SWCNT) is introduced as a better CH2O detector due to the electronic properties variation of Pd/SWCNT by adsorption of CH2O. The obtained results demonstrate very well that the O atom of CH2O would prefer to close Pd-loaded carbon nanotube rather than the H atom and CO bond. Furthermore, the molecular orbital studies indicate that the interaction between the Pd lone pairs of Pd/SWCNT and O lone pairs of CH2O orbital would create the main bonding between the CH2O molecule and the Pd site. More importantly, the larger values concerning to the adsorbing energy and charge transfer for that CH2O adsorbed on Pd/SWCNT system present a strong chemisorption. By the Bader theory of atoms in molecules (AIM), the topological properties of the electron density contributions for intermolecular and intramolecular interactions have been analyzed. Finally, the natural bond orbital (NBO) analyses were carried out and expatiated in order to better understanding of the aforementioned interactions.