Engineering of high surface defects in 2D-MoS2 nanostructures through CTAB surface functionalization for highly selective CO gas sensing

Abstract

A highly selective chemoresistive CO gas sensor is developed based on the ammonium surfactant functionalized hierarchical microspheres of 2D-MoS₂ (C-MoS₂) nanosheets. The samples were synthesized via a facile one-step hydrothermal process. The C-MoS₂ was annealed at 400 °C to prepare the CA-MoS₂. As a result, high surface area, enhanced defects, and reduced high-energy binding sites were formed in the CA-MoS₂. Detailed analysis revealed the presence of tensile strain, breakage of the lamellae, and point defects in CA-MoS₂. These conditions facilitated a fast exothermic reaction between CO gas and CA-MoS₂ following the Langmuir-Hinshelwood mechanism. The developed gas sensors are exposed to CO, NO₂, NH₃, and H₂ gases in a temperature range of 150–300 °C. The optimized CA-MoS₂ showed high selectivity and sensitivity of 4.1 % towards 80 ppm of CO at 250 °C. Good cyclic reproducibility and stability over five weeks are also observed for the sensor.