Electric field-modulated high sensitivity and selectivity for NH3 on α-C2N2 nanosheet: Insights from DFT calculations

•Eads of NH3 on α-C2N2 varied from −0.83 to −0.24 eV by controlling VE.•I-V curves show that NH3 can be measured directly in practical application.•α-C2N2 could be used as highly sensitive and selective NH3 sensor. An electric field-modulated α-C2N2 of high sensitivity and selectivity toward NH3 has been studied by using the first-principle calculations. Firstly, the structural stability of α-C2N2 nanosheet is proved by phonon dispersion and molecular dynamics calculations. Then, the adsorption energies and electronic properties of CO, CO2, H2, NO2, NH3, O2, N2, SO2 or CH4 on α-C2N2 are calculated, with the discussion about the possibility of α-C2N2 used as NH3 sensors. The results show that the amount of charge transfer for NH3 on α-C2N2 is the most in these nine adsorption systems. Therefore, NH3 could be easier detected in experiments. Next, we find that the adsorption energies of NH3 on α-C2N2 varied from −0.83 eV to −0.24 eV under the external electric field (VE) from VE = −0.6 V/Å to VE = +0.3 V/Å. Therefore, the adsorption and desorption of NH3 on α-C2N2 can be well realized under the control of VE. α-C2N2 nanosheet has the potential to be used as highly sensitive and selective NH3 sensor by controlling VE. More importantly, the current-voltage curves of NH3 before and after adsorption on α-C2N2 has changed significantly, which means that NH3 can be measured directly in practical application.