Two-dimensional graphitic carbon nitride (g-C4N3) for superior selectivity of multiple toxic gases (CO, NO2, and NH3)

Using first principles calculations, we investigated the possibility of selecting multiple toxic gases using one substrate material. Here, we explored the transport property of H2, N2, O2, CO, CO2, NO2, and NH3 gas molecules on two-dimensional graphitic carbon nitride (2D g-C4N3). The homonuclear molecule such as H2, N2, and O2 has very weak adsorption energy (equal to or less than 0.1 eV) and also CO2 has an adsorption energy of 0.23 eV. In the typical toxic gas molecule adsorption systems, we found an appreciable charge transfer. In CO and NH3 adsorption systems, the charge transfer of 0.397 and 0.418 electrons from the molecule to the substrate was found, while the NO2 molecule gained 0.124 electrons from the substrate. Due to this large amount of charge transfer, we obtained large adsorption energies of 4.57, 1.29, and 1.93 eV in CO, NO2, and NH3 systems. Moreover, through the I–V curve calculations, we found large difference in the current. The calculated current was 21, 13.11, and 16.16 μA for CO, NO2, and NH3 systems at the bias voltage of 0.5 V. Our results imply that the 2D g-C4N3 can be a superior substrate material for sensing of multiple toxic gases.