Highlights
- Spray-pyrolysis V2O5 nanofibers were tuned by varying precursor concentration from 0.025 to 0.1 M.
- Interconnected, flower-like nanofibers formed at the highest precursor concentration (0.1 M), giving the largest surface area.
- The 0.1 M nanofiber film showed the highest selectivity toward xylene among eight tested vapors, at room temperature.
- Response scaled across a wide 5-1000 ppm xylene range and remained stable over 30 days.
Abstract
Vanadium pentoxide (V2O5) nanofibers were deposited on glass by spray pyrolysis, with precursor concentration varied from 0.025 to 0.1 M to control the film's crystal structure and fiber morphology. Higher precursor concentration shifted the film from amorphous to polycrystalline and produced interconnected, flower-like nanofibers with more surface area. The nanofiber film deposited at 0.1 M gave the strongest and most selective response toward xylene among eight tested vapors, covering a wide concentration range of 5 to 1000 ppm at room temperature, and stayed stable over a month of repeated testing. The results position V2O5 nanofibers as a strong room-temperature alternative to sensors that require elevated operating temperatures.
Research summary
Xylene exposure is linked to headaches, respiratory irritation, and longer-term health risks, and it is released widely from petrochemical and industrial processes. Many metal oxide gas sensors exist to detect it, but combining strong selectivity — picking out xylene from similar vapors — with room-temperature operation remains difficult. This study investigates vanadium pentoxide (V2O5) nanofibers, prepared by spray pyrolysis, as a candidate that can do both.
What the study examined
- V2O5 thin films spray-deposited on glass from ammonium metavanadate precursor solutions at four concentrations (0.025, 0.050, 0.075, and 0.1 M).
- How precursor concentration affected crystal structure (from amorphous to polycrystalline), fiber morphology, and film thickness.
- Sensing response toward xylene at concentrations from 5 to 1000 ppm at room temperature.
- Selectivity against seven other vapors (formaldehyde, ethanol, toluene, methanol, acetone, acetaldehyde, ammonia) and stability over 30 days of repeated testing.
Main findings
Increasing the precursor concentration shifted the V2O5 film from an amorphous state toward a polycrystalline one, and produced increasingly interconnected, flower-like nanofibers. The film deposited at the highest concentration tested (0.1 M) had the most developed nanofiber network and the roughest surface, which gave it substantially more area for gas molecules to interact with.
This 0.1 M nanofiber film performed best as a sensor by a wide margin. Its response to 500 ppm xylene was three to five times higher than the films made at lower precursor concentrations. Against a panel of eight vapors, its response to xylene (191) was far higher than to any interferent — for comparison, formaldehyde gave 13, ethanol gave 6.75, and ammonia gave 23 — demonstrating strong selectivity. The response also scaled consistently across a wide concentration window, from 5 up to 1000 ppm, and remained stable across 30 days of repeated exposure to 500 ppm xylene, with response and recovery times of about 80 and 50 seconds.
Why it matters
The results suggest that tuning nanofiber morphology through precursor concentration, rather than through more complex synthesis routes, is enough to build a xylene sensor that is both highly selective and stable, and that works at room temperature rather than requiring elevated operating temperatures. That combination is attractive for practical, lower-power air-quality monitoring devices.
Citation
Y. Vijayakumar, G. K. Mani, P. Dhivya, Prabakaran Shankar, K. Arockia Jayalatha, K. Tsuchiya, J. B. B. Rayappan, M. V. Ramana Reddy. V2O5 Nanofibers: Potential Contestant for High Performance Xylene Sensor. Journal of Alloys and Compounds 731 (2018) 805-812.
