Best of Both Worlds: New Organic–Inorganic Gas Sensors for Better Air Quality Monitoring
Scientists develop novel gas sensors with improved detection sensitivity and durability by combining organic and inorganic materials
With air pollution increasing year-on-year, the need for efficient, portable, and low-cost gas sensors that can detect toxic gases in real time grows stronger. Organic polymer-based sensors have the potential to fulfill all these requirements, but they’re not durable at room temperature. Now, researchers from Korea have solved this durability problem through a hybrid organic-inorganic design, while maintaining high detection sensitivity.
With air pollution on the rise, especially in densely populated urban areas, testing for air quality and the presence of pollutant gases, such as carbon dioxide, nitrogen dioxide (NO2), and carbon monoxide, have become more important than ever. Sensitive gas sensing and monitoring technologies are, therefore, a pressing need.
Of much recent research interest in this field are the novel organic field-effect transistor-based (OFET) sensors, which are highly sensitive, flexible, and lightweight, opening doors to portable gas sensors even on e-skins. However, OFETs are unstable, and therefore not durable, at room temperature. This limits their applicability and makes them inferior to existing inorganic sensors, which nonetheless, do not possess any of the flexibility and light weight of organic sensors.
Bridging the organic–inorganic gap, scientists from Incheon National University, Korea, led by Prof. Yeong Don Park, have created hybrid OFETs using a organic conjugated polymer and variations of an inorganic nanoporous material, zeolite. Their study was made available online on 6 April 2021 and will be published in Volume 420 Part 1 of Chemical Engineering Journal on 15 September 2021.
“The high degree of porosity in zeolite results in an exceptionally high specific surface area and, in turn, a strong adsorption response for small gas molecules. This also helps it adsorb the molecules in air that oxidize (react with) the gas sensor to destabilize it and reduce its durability.” explains Prof. Park. Their material boasts not only high durability, but also high sensitivity.
The team fabricated two OFET-based NO2 sensors using a combination of the conjugated polymer, poly(3-hexylthiophene) (P3HT) and one of two zeolite materials, PST-11 or Omega. They examined the sensing performances of both OFETs when exposed to NO2 gas. The hybridization provided the polymer with an orderly structure which in turn led to efficient interactions with the gas molecules and, consequently, high sensitivity. Among the two, the scientists observed that the PST-11–P3HT film was more sensitive to NO2 than the Omega–P3HT film due to a larger specific surface area.
Overall, Prof. Park explains: “Our approach represents a new way of conceptualizing the design and development of sensors. If our research is refined further, people can easily detect harmful gases in real time.” Speaking of his vision, he says: “Our devices can be integrated with wearable devices such as smart watches and e-skins to allow people to know about air pollution levels in areas other than industrial sites.”
While a pollution-free world is our end goal, it certainly wouldn’t hurt to stay safe while we get there.
Authors: Eun Hye Kwon (1), Hyejin An (2), Min Bum Park (1), Min Kim (2) and Yeong Don Park (1)
Title of original paper: Conjugated polymer–zeolite hybrids for robust gas sensors: Effect of zeolite surface area on NO2 sensing ability
Journal: Chemical Engineering Journal
Corresponding author: Yeong Don Park
Corresponding author’s email: email@example.com
(1) Incheon National University, Korea
(2) Jeonbuk National University, Korea
About Incheon National University
Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.
About the authors
Professor Yeong Don Park focuses on research on the fabrication and characterization of conductive polymer-based devices, and Professor Minbum Park conducts research on zeolite’s gas adsorption. Together, they fuse two different research fields of organic and inorganic matter; this synergistic effect gives rise to excellent, high-quality, and innovative research!