A novel high-performance methane sensor based on Ti-Decorated 2D γ-graphyne: A dispersion-corrected DFT insight

In the present theoretical study, the effect of methane adsorption on the electronic properties of titanium (Ti)-decorated γ-graphyne (γ-GY) is investigated. To this end, the dispersion-corrected density functional theory (DFT-D2) is employed to explicitly include the van der Waals interactions (vdW) in the computations. The results show that the methane is physisorbed on the γ‒GY owing to the low binding energy and relatively long adsorption distance. According to our calculations, Ti atom is chemically bound to four sp carbon atoms with the binding energy of −4.960 eV (per supercell) and provide an appropriate adsorption site for reducing gas molecule such as methane. We also observe that the methane molecule chemisorbed on the Ti-decorated γ-GY with the binding energy of −0.594 eV per supercell. Moreover, upon methane adsorption, the electronic bandgap of Ti-decorated γ-GY reduces about 0.051 eV. Our results reveal that Ti-decorated γ-GY has excellent sensing efficiency for CH 4 gas with high selectivity and fast recovery time. Therefore, the present work encourages the growing use of Ti-decorated γ-GY for the development of thermopower-based, resistive-based, or quartz crystal microbalances-based methane sensors. • Methane sensing properties of Ti-decorated γ-graphyne (γ-GY) are investigated. • Van der Waals interactions are included in DFT computations. • Physisorption of CH 4 on pristine γ-GY minutely changes its electronic properties. • CH 4 chemisorption on Ti-decorated γ-GY increases the carrier conductance. • Ti-decorated γ-GY forms a feasible thermopower- and resistance-based CH 4 sensor.