Field-effect transistors (FET) receive growing attention for gas detection owing to their superior sensing performance over traditional techniques. The sensitivity and selectivity of FET sensor can be enhanced through tuning the structure of channel material via doping, surface functionalization, hybridization, etc. However, the intrinsic semiconductor characteristics of the channel materials and their gas adsorption capacity largely determine the sensing performance. This work compares the room temperature sensing performance of FET sensors with few-layer graphene, black phosphorous (BP), and MoS2 with mixed polymorphic phases (metallic 1T phase and semiconducting 2H phase), and 2H-MoS2 as channel material for formaldehyde, a typical hazardous volatile organic compound (VOC). The gas sensing results show that the heterophase 1T/2H-MoS2 exhibits the best sensitivity, response time as well as selectivity for formaldehyde detection. The density functional theory (DFT) simulation demonstrates that 1T/2H-MoS2 owns the optimum semiconducting properties and gas adsorption capability for formaldehyde over 2H-MoS2, graphene, and BP. Moreover, by investigating the sensing performance under different humidity conditions, it is discovered that high humidity enhances the sensing signal, which can be ascribed to the contribution from adsorbed water molecule. This study offers a vital guideline to the development of 2D nanostructure as channel in FET gas sensors, which demonstrates that the regulation of their intrinsic electronic structures directly affect the gas detection performance.

Understanding the intrinsic sensing behaviors of 2D nanomaterials for volatile organic compound: From graphene to MoS2 and black phosphorous

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.