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Open AccessArticle

Effects of pH on High-Performance ZnO Resistive Humidity Sensors Using One-Step Synthesis

School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China
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Sensors 2019, 19(23), 5267; https://doi.org/10.3390/s19235267
Received: 12 November 2019 / Revised: 26 November 2019 / Accepted: 28 November 2019 / Published: 29 November 2019
(This article belongs to the Section Chemical Sensors)
In this paper, we prepared a high-performance zinc oxide (ZnO) humidity sensor in an alkaline environment using one-step hydrothermal method. Experiments showed that the pH value of the precursor solution affects the performance of ZnO humidity sensors. There are abundant hydroxyl group and oxygen vacancies on the surface of ZnO with a precursor pH value of 10. Abundant hydroxyl groups on the surface of ZnO can adsorb a large number of water molecules and rich oxygen vacancies can accelerate the decomposition of water molecules, thus increasing the number of conductive ions (H3O+) and further improving the performance of the sensor. So, such a ZnO humidity sensor exhibited high sensitivity (14,415), good linearity, small hysteresis (0.9%), fast response/recovery time (31/15 s) in the range from 11% to 95% relative humidity (RH). Moreover, the ZnO-2 humidity sensor has good repeatability and can be effectively used for a long time. This study provides a new idea for the development of low-cost, high-performance and reusable ZnO resistive humidity sensors. View Full-Text
Keywords: humidity sensor; zinc oxide; pH value; hydroxyl group; oxygen vacancies humidity sensor; zinc oxide; pH value; hydroxyl group; oxygen vacancies
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Yu, S.; Zhang, H.; Zhang, J.; Li, Z. Effects of pH on High-Performance ZnO Resistive Humidity Sensors Using One-Step Synthesis. Sensors 2019, 19, 5267.

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