A newly developed gas sensor could make detecting ethylene glycol (EG) safer and more efficient, according to a study published in Sensors.
Study: Ultra-Sensitive Gas Sensor Based on CDs@ZnO. Image Credit: chemical industry/Shutterstock.com
EG, a volatile organic compound (VOC) widely used in industry, poses serious health risks, including dizziness, nausea, and potential long-term organ damage if inhaled. Researchers behind the study say their innovative sensor offers a faster and more accurate way to identify EG in the environment, a crucial step in ensuring public safety and industrial compliance.
Background
EG is widely utilized but presents serious health hazards. Traditional detection methods, while effective, typically require sophisticated laboratory setups and trained personnel, making them impractical for real-time monitoring. In contrast, gas sensors offer a compact, cost-effective, and continuous monitoring solution. Among these, metal oxide semiconductor (MOS)-based sensors have gained attention for their high sensitivity and real-time detection capabilities.
Recent advancements have explored the integration of carbon dots (CDs) with zinc oxide (ZnO) to enhance sensor performance. Carbon dots possess unique electronic properties and strong gas interactions, making them ideal for improving the functionality of traditional ZnO-based sensors.
The Study
In this study, the researchers used a hydrothermal synthesis method to create a three-dimensional, sea urchin-shaped ZnO structure, which increases the material’s surface area and enhances its interaction with gas molecules. Carbon dots were then incorporated into the ZnO matrix using a straightforward mechanical grinding process, resulting in a CDs@ZnO nanocomposite—the core sensing material of the gas sensor.
The composite was characterized using techniques such as Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) to analyze its morphology. The gas sensor was fabricated by coating the composite onto a ceramic substrate, followed by electrical connections and sensor aging at high temperatures to improve stability. Performance testing was conducted using a WS-30A gas sensor test system, where the sensor’s resistance change upon exposure to varying concentrations of EG was meticulously recorded.
Results and Discussion
The CDs@ZnO-based gas sensor demonstrated outstanding sensitivity and selectivity for ethylene glycol detection. The sensor achieved a peak response value of 1356.89 at 100 ppm EG under optimal operating conditions at 220 °C. Additionally, it exhibited fast response and recovery times, which are critical for real-time monitoring applications. Stability tests confirmed consistent sensor performance over multiple detection cycles.
Several factors contributed to this enhanced performance. The CDs@ZnO composite generated a high number of oxygen vacancies, improving gas interactions. Moreover, the formation of p-n heterojunctions between the carbon dots and ZnO facilitated efficient charge transfer, enhancing sensor sensitivity.
Selectivity was another key strength of this sensor. It responded significantly more to EG than to other VOCs, demonstrating its ability to distinguish EG from similar substances. This selectivity arises from the specific bond dissociation energies of the gases, making EG particularly reactive with the composite material. The study also provided a detailed explanation of the detection mechanism, describing how adsorbed oxygen on the sensor’s surface interacts with ethylene glycol to induce a measurable resistance change.
Conclusion
This research marks a significant step forward in developing high-performance gas sensors for EG detection. The innovative use of CDs@ZnO not only boosts sensitivity and selectivity but also ensures long-term stability and reliability. The findings highlight the potential of carbon dot-modified metal oxide semiconductors for practical applications in industrial and environmental monitoring.
As concerns over air quality and workplace safety continue to grow, advancements like this pave the way for more effective gas sensing solutions. Future research may explore further optimizations and broader applications of this technology to enhance environmental protection and public health measures.
Journal Reference
Xiao S., Jiao Z., et al. (2025). Ultra-Sensitive Gas Sensor Based on CDs@ZnO. Sensors 25(3):905. DOI: 10.3390/s25030905, https://www.mdpi.com/1424-8220/25/3/905