Electronic Modulation of MoS 2 Nanosheets by N-Doping for Highly Sensitive NO 2 Detection at Room Temperature.

Transition metal dichalcogenide (TMD) materials hold great promise for gas sensors working at room temperature (RT). But the low response and slow dynamics derived from pristine TMDs remain a challenge toward their real applications. In this work, we report an efficient N-doping strategy to modulate the electronic structure of MoS 2 nanosheets (N-MoS 2 ) to achieve improved detection toward NO 2 . The effect of N-doping on the sensor properties, which has been rarely investigated, is elucidated by both experimental and computational studies. Due to N-doping, the Fermi level of N-MoS 2 decreased from -5.29 to -5.33 eV and the band gap was reduced from 1.79 to 1.65 eV. The smaller band gap indicated the reduced resistance of N-MoS 2 compared to that of original MoS 2 . As a result, the response of the MoS 2 sensor to 10 ppm of NO 2 was improved from 1.23 to 2.31 at RT. The sensor also has a limit of detection (LOD) of 62.5 ppb. To explain the effect of N-doping, density functional theory (DFT) calculations were conducted to figure out the important roles played by N-doping. This work demonstrates a pathway to modulate the chemical and electronic structures of TMD materials for advanced sensors.