Phase-Dependent Dual Discrimination of MoSe/MoO Composites Toward ,-Dimethylformamide and Triethylamine at Room Temperature.

Herein, we present, a chemiresistive-type gas sensor composed of two-dimensional 1T-2H phase MoSe and MoO. Mixed phase MoSe and MoSe/MoO composites were synthesized via a facile hydrothermal method. The structure analysis using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy revealed the formation of different phases of MoSe at different temperatures. With increase in synthesis temperature from 180 to 200 °C, the relative percentage of 1T and 2H-MoSe phases changed from 80 to 48%. On the other hand, at 220 °C, 2H-MoSe was obtained as a major component. The gas sensing properties of individual MoSe and composites were investigated at room temperature toward various analytes. The obtained results revealed that composites possess improved sensing features as compared with individual MoSe or MoO. Data also revealed that the composite with dominating 1T-phase exhibits relatively higher response (10%, at 10 ppm) for dimethylformamide (DMF) compared to triethylamine (TEA) (3%, at 10 ppm). In contrast, the composite with larger 2H-phase exhibited affinity toward TEA and had a relative response of about 2%. Therefore, selectivity of a sensor device can be tuned by an appropriately designed MoSe/MoO composite. These results signify the importance of MoO-based composites with dual-phase MoSe for successfully discriminating between DMF and TEA at room-temperature.