MXenes provide exceptional signal-to-noise ratios in gas sensing | February 5, 2018 Issue - Vol. 96 Issue 6 | Chemical & Engineering News
Volume 96 Issue 6 | p. 11 | Concentrates
Issue Date: February 5, 2018

MXenes provide exceptional signal-to-noise ratios in gas sensing

Metallic conductivity and reactive surface groups take credit for 2-D material’s performance
Department: Science & Technology
News Channels: Analytical SCENE, Materials SCENE, Nano SCENE
Keywords: 2-D materials, chemical sensing, gas sensor, maxene, MXene
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High conductivity and the presence of –O, –OH, and –F surface groups make this titanium carbide MXene useful for sensing gases (ethanol and ammonia shown). Ti = yellow, C = black, H = white, O = red, F = blue, N = green.
Credit: Adapted from ACS Nano
This drawing depicts the structure of a titanium carbide MXene compound and gas molecules adsorbing to it.
 
High conductivity and the presence of –O, –OH, and –F surface groups make this titanium carbide MXene useful for sensing gases (ethanol and ammonia shown). Ti = yellow, C = black, H = white, O = red, F = blue, N = green.
Credit: Adapted from ACS Nano

Gas sensors have long served critical roles in industrial applications, including monitoring air quality and engine emissions. Analyzing volatile organic compounds in breath to screen for disease markers is a developing application that is being advanced by highly sensitive “homemade” gas sensors, often based on semiconducting oxides, nanomaterials, and two-dimensional materials. That field may advance even more quickly now thanks to a study showing that a titanium carbide MXene compound can be fashioned into a gas sensor that provides part-per-billion-level sensitivity and record-setting signal-to-noise ratios (ACS Nano 2018, DOI: 10.1021/acsnano.7b07460). Various 2-D materials, including black phosphorus and molybdenum disulfide, rank among the top-performing gas-sensing media. That motivated a team led by Hee-Tae Jung of Korea Advanced Institute of Science & Technology and Yury Gogotsi of Drexel University to see how MXenes, a family of 2-D metal carbides and nitrides, stack up in that application. Head-to-head comparisons in tests with acetone, ethanol, ammonia, propanal, and other gases relevant to breath analysis show that the MXene compound evaluated, Ti3C2, provides signal-to-noise ratios roughly 100 times as high as those of the other 2-D materials. The team attributes the excellent performance to the MXene’s porosity, metal-like conductivity, and abundant surface groups that adsorb analytes.

 
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