Dual-catalytic activation of Pt and MoSxOy on carbon nanofibers for NO2 sensors

Abstract

To achieve highly sensitive chemiresistive gas sensors, facile and effective synthesis for catalytic decoration is essential on an electrically conductive scaffold containing a large surface area and high porosity. Herein, we report a new synthetic strategy for the functionalization of one-dimensional carbon nanofibers (CNFs) using dual-catalytic nanoparticles (NPs) of both oxygen-incorporated MoS2 (MoSxOy) and Pt. The functionalized CNFs were synthesized through an electrospinning process followed by heat treatment in a reducing ambient to ensure the decoration of ultra-small MoSxOy and Pt NPs along the CNFs (Pt-MoSxOy@CNFs). As a result, Pt-MoSxOy@CNFs exhibited an improved sensing response of 39.6% toward 5 ppm of NO2 as compared to the responses of pristine CNFs (7.3%) and MoSxOy@CNFs (13.7%) at room temperature. At the optimized operating temperature of 150 °C, the Pt-MoSxOy@CNFs exhibited a 5.8-fold higher response than that of the pristine CNFs and also presented fully reversible and selective sensing properties. The enhanced NO2 sensing properties were primarily attributed to the chemical sensitization of Pt NPs toward NO2 and a p-n heterojunction between the CNFs and MoSxOy NPs. This study demonstrates the uniform distribution of multiple nano-sized catalysts on CNFs, paving the way for establishing multiplexed sensor arrays and application in electronic nose systems.