High-Performance Humidity Sensor Based on the Graphene Flower/Zinc Oxide Composite

• Main Authors: Muhammad Saqib, Shenawar Ali Khan, Hafiz Mohammad Mutee Ur Rehman, Yunsook Yang, Seongwan Kim, Muhammad Muqeet Rehman, Woo Young Kim
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Nanomaterials
• Subjects: functional material; graphene flower and ZnO composite; sol–gel method; ultra-sensitive humidity sensor; fast response/recovery time; health monitoring applications
• Online Access: https://www.mdpi.com/2079-4991/11/1/242

Performance of an electronic device relies heavily on the availability of a suitable functional material. One of the simple, easy, and cost-effective ways to obtain novel functional materials with improved properties for desired applications is to make composites of selected materials. In this work, a novel composite of transparent n-type zinc oxide (ZnO) with a wide bandgap and a unique structure of graphene in the form of a graphene flower (GrF) is synthesized and used as the functional layer of a humidity sensor. The (GrF/ZnO) composite was synthesized by a simple sol–gel method. Morphological, elemental, and structural characterizations of GrF/ZnO composite were performed by a field emission scanning electron microscope (FESEM), energy-dispersive spectroscopy (EDS), and an x-ray diffractometer (XRD), respectively, to fully understand the properties of this newly synthesized functional material. The proposed humidity sensor was tested in the relative humidity (RH) range of 15% RH% to 86% RH%. The demonstrated sensor illustrated a highly sensitive response to humidity with an average current change of 7.77 μA/RH%. Other prominent characteristics shown by this device include but were not limited to high stability, repeatable results, fast response, and quick recovery time. The proposed humidity sensor was highly sensitive to human breathing, thus making it a promising candidate for various applications related to health monitoring.