Detection of nonpolar n-dodecane at room temperature using multiphase MoS2 chemiresistive sensor: Investigation of charge transfer on nonpolar VOC molecule

Abstract

Room temperature chemiresistive sensors are potential for the noninvasive disease diagnostics by detecting volatile organic compound biomarkers from exhaled breath. In this work, we fabricated a molybdenum disulfide (MoS2) chemiresistive sensor for highly selective detection of the nonpolar n-dodecane at room temperature. X-ray diffraction and Raman spectroscopy studies confirmed the presence of the multiphase (metallic 1 T phase along with the semiconducting 2 H phase) MoS2. The field emission scanning electron microscopic images showed the flower-like interconnected MoS2 sheets with an average size of 10–15 nm. Compared to the single-phase 2 H MoS2 sensor, the multiphase (1 T/2 H) MoS2 sensor showed a higher response and could detect the n-dodecane concentration as low as 400 ppb. The response and recovery time of the sensor were calculated as 40 s and 60 s, respectively. The multiphase MoS2 sensor exhibited better sensing properties toward the detection of n-dodecane from the simulated breath sample with a relative error of ∼0.12. Interestingly, density functional theory analysis revealed that the presence of metallic 1 T phase in the multiphase MoS2 is responsible for vapor adsorption and charge transfer in the n-dodecane sensing. The present results are promising for the development of room temperature nonpolar sensors.