Performance Optimization Of High-sensitivity Surface Acoustic Wave Hydrogen Sensors Based On Graphene Sensitive Layers

Currently,hydrogen exhibits great application potentials as a new type of clean and renewable energy resource because it meets the requirements of environmental protection and sustainable development.However,due to the characteristics of colorlessness,odorlessness,flammability and explosivity,high-sensitivity sensors are required to detect hydrogen with trace concentrations.In this work,a high-sensitivity hydrogen sensor on the basis of the Rayleigh wave is studied,in which a graphene-based sensitive layer modified by platinum is used to adsorb hydrogen.Then,due to the high performance of the graphene-based sensitive layer and the advantage of a surface acoustic wave sensor,a minimum detection limit of 500 ppb is achieved.This thesis is mainly divided into the following five parts:Chapter 1: The research background of hydrogen sensors is firstly introduced,as working mechanisms of various hydrogen sensors,the advantages of surface acoustic wave sensors and the selection of sensitive materials,the characteristics of graphene and the superiority of graphen-like sensitive layers in hydrogen sensing.Finally,the development of surface acoustic wave sensors based on graphen-like sensitive layers is presented.Chapter 2: The design and fabrication of our hydrogen sensor is presented,as the design of interdigital transducers and the growing of the sensitive layer.The Hummers method is used to produce graphite oxide and hydrothermal reduction method is adopted to obtain reduced graphene oxide.A drop coating method is used to grow the sensitive layer on the piezoelectric substrate and the magnetron sputtering method is used to grow platinum as a catalyzer.The scanning electron microscopy is used to evaluate the characteristics of the sensitive layer.Chapter 3: The performance of the hydrogen sensor is studied.The hydrogen sensor is tested under different conditions,which demonstrates that the sensor possesses an extremely high sensitivity and is available to detect hydrogen with trance concentrations.Furthermore,the stability of the sensor is studied.Chapter 4: The storage conditions of the sensor are optimized.We compare the influences of different conditions to the performance of the hydrogen sensor and present an optimized condition to store the sensor.Chapter 5: Conclusions of the thesis and prospects for the future research.