Ammonia sensor detects volatile compounds at room temperatures

Ammonia is a colorless gas frequently used in commercial, industrial, and agricultural settings. While broadly useful, ammonia can be explosive and poisonous even in low concentrations. Sensors to detect ammonia are essential tools to mitigate these dangers, but existing devices only work at high temperatures over 200 degrees Celsius.

Yao et al. developed a low temperature ammonia sensor which works down to 28 C. They used a hydrothermal method to create the sensor, made of a Ti₃C₂T_x/ZnO composite, and performed several analyses to demonstrate that the composite was successfully deposited and the zinc oxide was evenly distributed on ultrathin nanosheets.

“High operating temperatures are unsafe for explosive ammonia and undesirable in low power consumption and convenience applications,” author Yude Wang said. “Developing an original ammonia gas sensor with good detection capability under low operating temperatures makes a lot of sense.”

The researchers tested their design using different volatile organic compounds to measure its performance. The sensor showed excellent detection of ammonia at concentrations as low as 1 part per million. Theoretical calculations supported the findings by detailing the mechanism allowing the composite to detect the ammonia.

“We hope that this work provides a viable route for the development of selective ammonia gas sensors operating at low temperature,” Wang said.

The authors hope that the advanced capabilities of their sensor lead to new uses in other fields.

“We believe that the capability of such a sensor would be of great benefit in the field of medical disease diagnosis, for instance, where it could detect concentrations of ammonia exhaled by patients with kidney disease,” Wang said.

Source: “Low operating temperature and highly selective NH3 chemiresistive gas sensors based on a novel 2D Ti3C2Tx/ZnO composite with p-n heterojunction,” by Lijia Yao, Xu Tian, Xiuxiu Cui, Rongjun Zhao, Ting Chen, Xuechun Xiao, and Yude Wang, Applied Physics Reviews (2023). The article can be accessed at https://doi.org/10.1063/5.0138182 .