Influence of Different Synthesis Methods on the Defect Structure, Morphology, and UV-Assisted Ozone Sensing Properties of Zinc Oxide Nanoplates
Abstract: In this work, room-temperature UV-assisted ozone detection was investigated using ZnO nanoplates synthesized via precipitation, ultrasound-, ultrasonic tip-, and microwave-assisted hydrothermal (MAH) methods. X-ray diffraction confirmed the formation of crystalline phases with an ~3.3 eV band gap, independent of the synthesis used. Raman spectroscopy revealed oxygen-related defects. Plate-like morphologies were observed, with the ultrasonic tip-assisted synthesis yielding ~17 nm-thick plates. Electrical measurements showed 10–170 ppb ozone sensitivity under UV. The sample synthesized via the MAH method (ZM) demonstrated superior conductance, with a baseline resistance of ~1.2% for the ultrasound (ZU) sample and less than 50% for the precipitation (ZA) and ultrasonic tip (ZP) samples. Despite the appreciable response in dark mode, the recovery was slow (>>30 min), except for the UV illumination condition, which reduced the recovery response to ~2 min. With top areas of ~0.0122 µm2, ZP and ZU showed high specific surface areas (24.75 and 19.37 m2/g, respectively), in contrast to ZM, which exhibited the lowest value (15.32 m2/g) with a top area of ~0.0332 µm2 and a thickness of 26.0 nm. The superior performance of ZM was attributed to the larger nanoplate sizes and the lower baseline resistance. The ultrasound method showed the lowest sensitivity due to the higher resistance and the depletion layer effect. The results indicate that the synthesis methods presented herein for the production of reactive ZnO nanoplates using NaOH as a growth-directing agent are reliable, simple, and cost-effective, in addition to being capable of detecting ozone with high sensitivity and reproducibility at concentrations as low as 10 ppb.
Author(s): Pedro P. Ortega, João V. N. Palma, Ana L. Doimo, Laura Líbero, Gabriel F. Yamakawa, Leonnam G. Merízio, Ederson C. Aguiar, Luís F. Silva and Elson Longo
Chemosensors
Published: 20 April 2025
DOI: https://doi.org/10.3390/chemosensors13040152
CDMF
The CDMF, hosted at the Federal University of São Carlos (UFSCar), is one of the Research, Innovation and Dissemination Centers (RIDC) supported by the São Paulo State Research Support Foundation (Fapesp), and also receives investment from the National Council Scientific and Technological Development (CNPq), from the National Institute of Science and Technology of Materials in Nanotechnology (INCTMN).
