Highlights
- ZnO nanospheres and nanorods were produced by laser ablation of zinc metal in water, using nanosecond and millisecond lasers respectively.
- Both nanomaterials were tested as room-temperature gas sensors toward ethanol, ammonia, and acetone.
- Both showed selectivity for ethanol, with nanospheres responding somewhat more strongly than nanorods.
- Ethanol concentrations as low as 50 ppm could be detected.
Abstract
This rapid communication reports room-temperature ethanol sensing using ZnO nanomaterials made by pulsed-laser ablation of a zinc target in water, a fast, chemical-free synthesis route. Nanosecond and millisecond lasers produced two contrasting hexagonal-wurtzite ZnO nanostructures, nanospheres and nanorods, which were drop-cast onto electrodes and tested toward ethanol, ammonia, and acetone. Both nanomaterials showed clear selectivity for ethanol at room temperature, with nanospheres giving a somewhat stronger response (over 19 at 250 ppm) than nanorods (over 14 at 250 ppm), and detection possible down to 50 ppm.
Research summary
Detecting volatile organic compounds such as ethanol in the air is important for indoor air quality and safety monitoring, and chemiresistive metal oxide sensors are a popular low-cost option. This rapid communication reports on ZnO nanomaterials made by laser ablation of a zinc metal target submerged in water – a fast, simple, chemical-free synthesis route – and tests how well they sense ethanol at room temperature.
Two types of pulsed lasers, nanosecond and millisecond, were used to ablate zinc metal in water for 30 minutes. The resulting ZnO colloids were collected and used to make gas sensors by drop-casting them onto interdigitated electrodes.
What the study examined
- ZnO nanomaterials produced by nanosecond-pulsed and millisecond-pulsed laser ablation of zinc in water
- Crystal structure and morphology of the resulting nanomaterials, using X-ray diffraction and transmission electron microscopy
- Room-temperature gas-sensing response and selectivity toward ethanol, ammonia, and acetone
- Comparison of sensing performance between the two laser-derived nanostructures
Main findings
The nanosecond laser produced ZnO nanospheres, while the millisecond laser produced ZnO nanorods, both with a hexagonal wurtzite crystal structure. Despite this difference in shape, both nanomaterials showed clear selectivity for ethanol over ammonia and acetone at room temperature.
The nanospheres gave a somewhat stronger ethanol response than the nanorods – above 19 versus above 14 toward 250 ppm ethanol – and both devices could detect ethanol concentrations as low as 50 ppm.
Why it matters
The study demonstrates that laser ablation in water is a viable, chemical-free route to ZnO nanomaterials that work as sensitive, selective, room-temperature ethanol sensors. Because the laser type alone (nanosecond versus millisecond) was enough to switch the resulting nanostructure and its sensing performance, this points to a simple lever for tuning sensor materials, with further work on doping and morphology control expected to improve performance further.
Citation
T. Kondo, Y. Sato, M. Kinoshita, Prabakaran Shankar, N. M. Neli, M. Honda, S. Iwamori, S. A. Kulinich. Room Temperature Ethanol Sensor Based on ZnO Prepared via Laser Ablation in Water. Japanese Journal of Applied Physics 56 (2017) 080304.
