Research On The Palladium-based Microfiber Gas Sensor For Low-concentration Hydrogen Gas Detecting

Nowadays,hydrogen gas,as one of cleanest energy,has attracted attentions from all over the world.Especially in China,hydrogen gas has accounted for 12.1%in renewable energy by 2004.Therefore,a sensitive hydrogen gas sensor with low limit detectability is extremely required as soon as possible.In this paper,we report several palladium-based nanofiber gas sensors,which was designed for fast and stable detecting of low-concentration hydrogen gas.Firstly,principle and mathematical model of palladium-hydrogen system were concluded,which raised several important problems in the design of palladium-based hydrogen gas sensor.Then a hydrogen gas sensor based on the closure of prepared fracture was designed and fabricated,which performed high sensitivity and fast response,however lack of stability made it not competent for a long-time detecting.Therefore,enhanced hydrogen gas sensor with improved stability and sensitivity,although which can only perform one-time detecting,was fabricated so as to serve as a long-time reliable hydrogen gas leakage detector.Finally,on the other hand,to achieve multiple detecting of hydrogen gas concentration over a wider range,we designed another hydrogen gas sensor with enhanced recovering speed owing to the vibration of specially designed substrate-a polymeric piezoelectric fiber with metal core produced by electrowetting aided dry spinning method.Achievements of this paper can be concluded as follows:1.Research on a highly sensitive structure based on the slight volume change during hydrogen adsorption.Narrow fracture was generated through a specially designed stretching aided hydrogen gas exposure method,through which the slight volume change was converted into large resistance change,resulting in the high sensitivity towards hydrogen gas sensing.2.Research on a reliable hydrogen leakage detector.The designated palladium sensing nanolayer underwent an irreversible cracking while being exposed to hydrogen gas,which induced a great resistance increases.Efficient and credible fabrication was investigated through a designed electrospinning device.After being well packaged,the sensors showed highly reliable response with good consistency.3.Research on the fabrication of polymeric piezoelectric fiber with metal core.An electrowetting aided dry spinning method was developed to produce morphologically stable polymeric piezoelectric fibers with metal core covered by beta phase poly(vinylidene fluoride)(or poly(vinylidene-trifluoroethylene))layer.Morphological properties of fibers were analyzed through scanning electron microscope,X-ray diffraction and step profiler.Piezoelectric properties were tested in a vibration detecting application.Both morphological observation and piezoelectric testing demonstrated that the electrowetting aided dry spinning helps forming high-quality polymeric piezoelectric fibers.4.Research on the enhancement of desorption speed through the vibration of polymeric piezoelectric fiber with metal core.Hydrogen gas sensor was design with polymeric piezoelectric fiber as substrate.Recovering time of this sensor was measured under different vibrating frequency and amplitude,so as to prove the effectivity of vibration towards the enhancement of desorption speed.