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

Abstract

Room-temperature (RT) detection of nitrous oxide ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> ) 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> is demonstrated using 2-D molybdenum disulfide (MoS <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{2}}{)}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> , 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> . 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> at room temperature compared to pristine MoS2 gas sensors due to the n-doping effect of AuNPs. Furthermore, the sensor can detect <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> levels as low as 0.5 ppm. Additionally, the incorporation of AuNPs on MoS2 nanoflakes improves the selectivity toward <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> against a variety of interfering gases, including ammonia, nitric oxide, ethylene, and carbon dioxide. The possible reason could be that the dominant chemisorption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}\text{O}$ </tex-math></inline-formula> gas sensing applications.

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