Highlights
- A PANI-CdO composite thin film sensor was built by dip-coating polyaniline (PANI) and cadmium oxide (CdO) nanoparticles at three CdO loadings.
- The film with 10 wt% CdO retained the most uniform CdO distribution and the highest surface-to-volume ratio.
- This composition gave a room-temperature methanol response of 1580 toward 100 ppm, higher than the authors' earlier PANI-only sensor (1169).
- Response and recovery times were 19 and 41 seconds, and the film stayed selective against isopropanol, benzyl alcohol, triethylamine, and acetaldehyde.
Abstract
This study developed a composite thin-film sensor from polyaniline (PANI), a conducting polymer, and cadmium oxide (CdO) nanoparticles for detecting methanol vapor at room temperature. Films with different CdO loadings (10, 20, and 30 weight percent) were dip-coated and compared for their structural, morphological, and sensing properties. The film with 10 wt% CdO retained the most uniform distribution of CdO nanoparticles across the porous PANI surface and gave the strongest and most selective response, reaching a sensing response of 1580 toward 100 ppm methanol with response and recovery times of 19 and 41 seconds, outperforming the authors' previous PANI-only sensor and several other reported nanocomposite methanol sensors.
Research summary
Industrial and vehicle emissions make continuous, low-cost monitoring of volatile pollutants like methanol important for environmental and workplace safety. This study built a room-temperature methanol sensor by combining polyaniline (PANI), a conducting polymer, with cadmium oxide (CdO) nanoparticles, aiming to take advantage of the electronic differences between the two materials.
What the study examined
- PANI and CdO nanoparticles synthesized separately, then combined into composite thin films by dip coating at three CdO loadings (10, 20, and 30 wt%)
- Structural and morphological changes in the composite as CdO content increased, using X-ray diffraction, electron microscopy, and infrared spectroscopy
- Room-temperature sensing response, selectivity, and response/recovery behavior toward methanol vapor
- Comparison of sensing performance against the authors’ earlier PANI-only sensor and other nanocomposite methanol sensors reported in the literature
Main findings
The composite with 10 wt% CdO kept the most uniform distribution of CdO nanoparticles across the porous PANI surface, preserving a high surface-to-volume ratio; higher CdO loadings caused the particles to clump together and reduced the available surface area. This 10 wt% composition also gave the strongest and most selective sensing response, reaching 1580 toward 100 ppm methanol at room temperature — a clear improvement over the authors’ earlier PANI-only sensor (1169) and several other nanocomposite methanol sensors reported elsewhere.
Response and recovery times were 19 and 41 seconds, and the sensor’s response to methanol was distinctly higher than to isopropanol, benzyl alcohol, triethylamine, or acetaldehyde vapors, indicating good selectivity. The response also increased linearly with methanol concentration up to 100 ppm before leveling off.
Why it matters
The results show that combining a conducting polymer with a metal oxide nanoparticle at the right ratio can improve both the surface accessibility and the sensing response of a room-temperature methanol sensor beyond what either material achieves on its own. Because the sensor works without heating, it points toward simpler, lower-power hardware for environmental and industrial methanol monitoring.
Citation
R. Paulraj, Prabakaran Shankar, G. K. Mani, L. Nallathambi, J. B. B. Rayappan. PANI-CdO Nanocomposite Thin Films as a Room Temperature Methanol Sensor. Journal of Electronic Materials 47 (2018) 6000-6006.
