MXene/SnS₂ Heterojunction for Detecting Sub-ppm NH₃ at Room Temperature

Abstract

Detection of ultralow concentrations of ammonia is very important in many applications such as fishing, poultry, agriculture, industry, biomedicine, and clinical diagnosis. However, detecting sub-ppm NH3 remains a challenge for chemiresistive-type gas sensors. Two-dimensional (2D) materials display tremendous potential for effective gas detectors that can be used in these applications. The as-developed MXene/SnS2 heterojunction-based chemiresistive-type sensor presents superior gas-sensing performance toward sub-ppm ammonia at room temperature. The sensor can detect NH3 concentrations down to 10 ppb at room temperature. It also displays excellent long-term stability, with a decline in the response at ∼3.4% for 20 days. The developed sensor also displays good selectivity toward NH3 relative to some potential interferents, such as HCHO, C2H5OH, CH3OH, C3H6O, benzene, and NO2. The measured in situ diffuse-reflectance infrared Fourier transform (DRIFT) spectra confirm that the products of nitric oxides during the chemical reactions occurred at the surface of MXene/SnS2. Density functional theory (DFT) based on the first principles was implemented to compute the adsorption ability of NH3 at the surface of the MXene/SnS2 heterostructure. This indicates that the enhancement in the sensing properties of the MXene/SnS2 heterostructure-based chemosensor could be ascribed to the stronger NH3 adsorption, better catalytical activity, and more effective charge transfer bestowed by the formed heterostructure and the electron-redistribution-assisted stronger extraction of electrons from the sensing material.

Au/α-Fe2O3/Ti3C2Tx MXene Nanosheet Heterojunctions for High-Performance NH3 Gas Detection at Room Temperature

“…In Figure S1, pure MXene possesses much lower resistance, and the MXene-based sensors show a p-type response, which is in agreement with the results in the literature. 48,49 Additionally, the response/recovery time of Au/ α-Fe 2 O 3 /Ti 3 C 2 T x MXene devices to 5 ppm NH 3 were evaluated to be 3 and 2 s, separately, suggesting that it is a high-performance ultra-fast NH 3 gas detection equipment. Gas-sensing selectivity is one of the key indicators used to judge the properties of gas-sensitive materials.…”

Room-temperature chemiresistive ammonia sensors based on 2D MXenes and their hybrids: recent developments and future prospects

“…This slurry is dried under ambient conditions and the composite is obtained in a powder form. 89 In both the synthesis procedures above, the ratio of MXenes and TMDs is better controlled as per requirement. The other way is to grow the TMC/TMD material on MXene sheets in situ via a hydrothermal route, which might give a better intercalation of TMC/TMD between MXene nanosheets.…”

A room-temperature gas sensor based on 2D Ni–Co–Zn ternary oxide nanoflakes for selective and sensitive ammonia detection

“…The World Health Organization (WHO) recommends that the concentration of NH 3 in the environment produced from everyday activities must be less than 35 ppm in 15 min and not more than 25 ppm in 8 h. [1][2][3] NH 3 in exhaled breath is considered as one of the crucial biomarkers for renal disease and peptic ulcers. 4 Hence, selective and sensitive determination of NH 3 gas in the range of 1-25 ppm is of prime significance for environmental monitoring, checking for safety and medicinal investigation. Moreover, for the benefit of patients, it is essential to fabricate an NH 3 sensor that can detect NH 3 at room temperature (RT) with a high response, long-term stability, and a low limit of detection.…”