Functionalization of Edge Sites from Mono-Layered WS2 Nanoflakes on Multitubular Carbon Nanofibers for Room-Temperature Gas Sensors

Abstract

Transition metal dichalcogenides (TMDs) such as molybdenum disulfide $(MoS_2)$ and tungsten disul-fide $(WS_2)$ have been actively studied in recent years due to wide range of potential applications. As a promising application, TMD gas sensors have been developed and intensively explored. More recently, it has been reported that edge sites of TMDs can contribute to highly enhanced gas adsorption proper-ties. Herein, we firstly demonstrate superior room temperature gas sensing properties of $WS_2$ edge func-tionalized carbon nanofibers (CNFs) with multiple tubular pores $(WS_2@MTCNFs)$. Copolymer-electrospinning route, which uses poly(styrene-acrylonitrile) as sacrificial templates and $WS_2$ precursor contained poly(acrylonitrile) as carbon matrix, offers highly gas permeable CNFs with single-layered $WS_2$ edge-rich surface. As a result, $WS_2@MTCNFs$ exhibits noticeable gas response (15% at 1 ppm of $NO_2$) at room temperature compared to the response of pristine CNFs (2% at 1 ppm of $NO_2$), which was attributed to the synergistic effects originated from high surface porosity with numerous elongated pore channels of MTCNFs and strong binding interactions between $WS_2$ edge sites and NO2.