Figure 3
From: Charge-transfer-based Gas Sensing Using Atomic-layer MoS2
Adsorption configurations and in situ PL.
(a, b) Top views of the most favourable configurations for NO2 (a) and NH3 (b) on the MoS2. The calculated adsorption energies were −0.14 eV for NO2 and −0.16 eV for NH3. The negative adsorption energies indicate that the adsorption process is exothermic, indicating that NO2 and NH3 molecules are likely to be adsorbed onto the surface of the MoS2. (c, d) In situ PL spectra recorded from the MoS2 with NO2 (c) and NH3 (d) molecules. The overall intensity of the PL spectra changes in the presence of NO2 and NH3 molecules. The PL intensities of the A+ trions and A0 excitons are either suppressed or increased by changes in the concentrations of the charge carriers. (e, f) Schematics of the charge density differences for MoS2 in the presence of NO2 (e) and NH3 (f) gas molecules. NO2 molecules on the surface of MoS2 act as electron acceptors, whereas NH3 molecules act as electron donors.
