MoS₂-NiO nanocomposite for H₂S sensing at room temperature

The layered 2-D materials, such as molybdenum disulfide (MoS₂), are among the most promising candidates for detecting H₂S gas at very low concentrations. Herein, we have designed a series of novel nanocomposites consisting of MoS₂ and NiO. These materials were synthesized via a simple hydrothermal method. The microstructure and morphology of nanocomposites were studied using different characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). These nanocomposites were used as gas sensors, and the highest response (6.3) towards 10 ppm H₂S was detected by the MNO-10 gas sensor among all the tested sensors. The response value (R_g/R_a) was almost three times that of pure NiO (R_g/R_a = 2). Besides, the MNO-10 sensor exposed good selectivity, short response/recovery time (50/20 s), long-term stability (28 days), reproducibility (6 cycles), and a low detection limit (2 ppm) towards H₂S gas at RT. The excellent performance of MNO-10 may be attributed to some features of MoS₂, such as a layered structure, higher BET surface area, higher active sites, and a synergistic effect between MoS₂ and NiO. This simple fabrication sensor throws a novel idea for detecting H₂S gas.