High-Sensitivity and Room-Temperature Nitrous Oxide Sensor Using Au Nanoparticles-Decorated MoS₂

Room-temperature (RT) detection of nitrous oxide ( $\text{N}_{{2}}\text{O}$ ) gas in the atmosphere is important for human health and mitigating greenhouse gas emissions. A 2-D transition metal dichalcogenide facilitates high specific surface area and abundant active sites for room-temperature detection of various gases. However, low sensitivity, slow response, and poor selectivity limit the room temperature gas sensing performance. Here, the development of room-temperature detection of $\text{N}_{{2}}\text{O}$ is demonstrated using 2-D molybdenum disulfide (MoS $_{{2}}{)}$ nanoflakes decorated with gold nanoparticles (AuNPs). The high specific surface area and excellent physical and chemical properties of MoS2 facilitate abundant active sites for adsorbing $\text{N}_{{2}}\text{O}$ , while the electron-donating effect of AuNPs modulates the electronic structure of MoS2 that can help to realize high sensitivity even at low concentrations of $\text{N}_{{2}}\text{O}$ . A facile solvent exfoliation method is utilized for preparing 2-D MoS2 nanoflakes and then functionalized with AuNPs. The MoS2-AuNPs sensor shows a 58% enhancement in sensor response for $\text{N}_{{2}}\text{O}$ at room temperature compared to pristine MoS2 gas sensors due to the n-doping effect of AuNPs. Furthermore, the sensor can detect $\text{N}_{{2}}\text{O}$ levels as low as 0.5 ppm. Additionally, the incorporation of AuNPs on MoS2 nanoflakes improves the selectivity toward $\text{N}_{{2}}\text{O}$ against a variety of interfering gases, including ammonia, nitric oxide, ethylene, and carbon dioxide. The possible reason could be that the dominant chemisorption of $\text{N}_{{2}}\text{O}$ on AuNPs-decorated MoS2 is more prevalent than that of other gases. Besides the enhanced response and excellent selectivity, the sensor shows good repeatability with a low relative standard deviation of 0.2% and stability over 30 days. Thus, this sensor could be a potential candidate for high-performance and room-temperature $\text{N}_{{2}}\text{O}$ gas sensing applications.