First-Principles Investigation of CH Adsorption on a Singly and Doubly Decorated (8,0) Single Wall Carbon Nanotube With Palladium/Oxygen Species

We employ dispersion-corrected density functional theory to study the adsorption of CH4 molecule on a singly and doubly decorated (8,0) single wall carbon nanotube (CNT80) with palladium atom and oxygen molecule. The obtained optimized energies indicate that double decoration with palladium atom and oxygen molecules significantly enhances the adsorption of methane on the CNT80, while single decoration with oxygen molecules gives rise to a weak physical bonding for methane molecules. Moreover, we observe that methane adsorption decreases the bandgap and the distance of the Fermi level to the top of the valance band of the doubly decorated CNT80. The calculated charge density plots and energy band diagrams demonstrate a charge transfer from doubly decorated CNT80 to CH4. Regarding the p-type nature of the structure, our results support the increment of the conductance of the doubly decorated CNT80 after methane adsorption, in agreement with a real measurement in the ambient conditions. This observation underlines the importance of ambient oxygen in the real performance of CNT-based gas sensors.

Automated summary

The study explores the adsorption of methane on singly and doubly-decorated carbon nanotubes using dispersion-corrected density functional theory. Results show that double decoration significantly enhances methane adsorption, while single decoration leads to weak physical bonding. Methane adsorption decreases the bandgap and results in charge transfer in the doubly decorated carbon nanotubes, increasing conductivity and underlining the importance of ambient oxygen in CNT-based gas sensors' performance.