Abstract
To realize a high response and high selectivity gas sensor for the detection dissolved gases in transformer oil, in this study, the adsorption of four kinds of gases (H2, CO, C2H2, and CH4) on Pd-graphyne was investigated, and the gas sensing properties were evaluated. The energetically-favorable structure of Pd-Doped γ-graphyne was first studied, including through a comparison of different adsorption sites and a discussion of the electronic properties. Then, the adsorption of these four molecules on Pd-graphyne was explored. The adsorption structure, adsorption energy, electron transfer, electron density distribution, band structure, and density of states were calculated and analyzed. The results show that Pd prefers to be adsorbed on the middle of three C≡C bonds, and that the band gap of γ-graphyne becomes smaller after adsorption. The CO adsorption exhibits the largest adsorption energy and electron transfer, and effects an obvious change to the structure and electronic properties to Pd-graphyne. Because of the conductance decrease after adsorption of CO and the acceptable recovery time at high temperatures, Pd-graphyne is a promising gas sensing material with which to detect CO with high selectivity. This work offers theoretical support for the design of a nanomaterial-based gas sensor using a novel structure for industrial applications.
Highlights
At present, 2D materials are attracting much attention after the successful synthesis of graphene by micromechanical exfoliation in 2004 [1]
Due to the high surface activity of γ-GY, and the emerge active sites caused by the introduction of Pd [42,44,45], in this study, we propose a density functional theory (DFT) study of four typical dissolved gases in transformer oil (H2, CO, C2H2, and CH4) which are adsorbed onto Pd-doped γ-GY
The double numerical plus polarization (DNP) method was considered as the basis set for all the calculations, and the DFT semi-core pseudopotential (DSSP) was selected to handle the electrons, that is, a norm-conserving pseudopotential was applied to calculate the core electrons to improve the calculation efficiency
Summary
2D materials are attracting much attention after the successful synthesis of graphene by micromechanical exfoliation in 2004 [1]. Several emerging 2D materials have been exploited, including transition metal dichalcogenides (TMDs) [5,6], isomers of graphene [7], metal carbides and nitrides [8], 2D metal-organic frameworks [9], etc. Because of their more flexible band structures, these materials could have more promising applications in the field of optical and electronic devices. Based on several theoretical studies of GY as a gas sensing material, pristine GY exhibits weak chemical interactions with most small gas molecules. Choosing the appropriate doping approach is essential for the selectivity of GY-based sensing materials
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