Highly Sensitive Detection of Dissolved Gases in Transformer Oil With Carbon-Doped ZnO Nanotube: A DFT Study

The first-principles density functional theory in combination with non-equilibrium Green’s function were applied to simulate the adsorption and electrical properties of the C-doped ZnO nanotube when exposed to dissolved volatile gas in transformer oil. In this study, three gases H
₂
, C
₂
H
₂
, and CH
₄
were chosen as dissolved gasses in transformer oil. Initially, the adsorption energy, gas distance, Mulliken charge analysis, and PDOS diagram for the most stable structures were studied. Therefore, current-voltage and sensor response simulations were performed for hydrogen and acetylene gases to evaluate the sensitivity and selectivity of C-doped ZnO nanotube. The results indicated C-doped ZnO nanotube as an appealing material for detecting hydrogen and acetylene gases while it is practically insensitive to methane gas. Moreover, it was found that the negative differential resistance trend disappeared after hydrogen adsorption along with a high sensor response to hydrogen gas (S
_max
= 74% at V = 3.5V); while the adsorption of acetylene could not remove this trend (S
_max
= 41% at V = 4V).