Gas-Sensing Properties of CuS-MoSe Nanosheets to NO and NH Gases.

CuS-MoSe was selected as a gas-sensing material to detect NO and NH. Based on density functional theory calculations, the adsorption structures, density of states, molecular orbit, and recovery time were studied to analyze the gas-sensing mechanism of CuS-MoSe to gases. Calculation results show that CuS clusters receive a stable doping structure on the MoSe surface. Compared with intrinsic MoSe, CuS-MoSe shows more excellent adsorption performance to NO and NH due to the active feature of the CuS dopant. After NO and NH adsorption, the energy gap decreases, indicating an improvement of the conductivity, which is greatly significant for gas sensing. For double NH adsorption, the conductivity of the entire system increases more than that of a double NO adsorption system, signifying the sensitivity of CuS-MoSe is greater for NH than NO. The results of theoretical recovery time show that CuS-MoSe is sensitive for NH detection at room temperature (298 K) and NO detection at high temperature (400 K).