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Bifunctional function of PDMS membrane in designing H2S sensors —humidity resistant and selectivity improved. Credit: Zhang Ruofan
A crew of researchers underneath the management of Prof. Meng Gang from the Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS), explored the usage of polydimethylsiloxane (PDMS) in creating high-performance, humidity-resistant hydrogen sulfide (H2S) sensors, offering a path in direction of the sensible utility of H2S chemiresistors in humid air environments.
The outcomes have been printed in ACS Applied Materials & Interfaces and Chemical Communication, respectively.
H2S is a colorless, flammable, explosive, extremely corrosive, and extremely poisonous fuel, which broadly exists in semi-closed and high-humidity places. Some oxides together with delafossite, ZnO, and CuO have a excessive response to H2S in dry air, however the humidity tends to intrude with the response of sensors. In addition, H2S is a extremely corrosive fuel, and its corrosiveness will increase with the rise of humidity. This results in fast corrosion and degradation of sensors in high-humidity environments, which turns into an essential problem for the sensible utility of sensors.
In order to resolve these issues, scientists evaporated a hydrophobic and semipermeable membrane of polydimethylsiloxane (PDMS) on the Pt single-atom anchored CuCrO2 by the thermal evaporation method.
Zhang Ruofan, first author of the paper, described the biofunctional role of PDMS as “killing two birds with one stone.”
PDMS had hydrophobic nature. It could effectively isolate the intrusion of water vapor in the environment, weakened the influence of environmental humidity on the sensor, and significantly improved the long-term stability of the sensor in a humid environment.
On the other side, the micropores in the PDMS membrane could effectively block methyl mercaptan (CH3SH) molecules whose diameter was slightly larger than H2S. It acted as a “molecular sieve”, further improving the selectivity of the sensor for H2S.
The humidity-resistant H2S sensor based on PDMS-coated CuCrO2 had a low operating temperature (100 ℃), high response (up to 151 for 5 ppm H2S at 50% relative humidity), high selectivity, and good long-term stability, which laid an important foundation for the practical application of H2S sensor in petrochemical, natural gas, and other fields.
References:
“Bifunctional role of PDMS membrane in designing humidity-tolerant H2S chemiresistors with high selectivity” by Ruofan Zhang, Zanhong Deng, Junqing Chang, Zhongyao Zhao, Shimao Wang and Gang Meng, 16 January 2023, Chemical Communications.
DOI: 10.1039/D2CC05880D
“Pt-Anchored CuCrO2 for Low-Temperature-Operating High-Performance H2S Chemiresistors” by Ruofan Zhang, Zanhong Deng, Lei Shi, Mahesh Kumar, Junqing Chang, Shimao Wang, Xiaodong Fang, Wei Tong and Gang Meng, 20 May 2022, ACS Applied Materials & Interfaces.
DOI: 10.1021/acsami.2c00619
