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A First-principles Study Of Adsorption Of NO And CO On The Pd Doped ZnO Surface

Posted on:2018-12-02Degree:MasterType:Thesis
Country:ChinaCandidate:Y T YanFull Text:PDF
GTID:2348330515451636Subject:Electronic Science and Technology
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With the rapid development of contemporary industrial and technology,how to effectively control the toxic and harmful gases,flammable and explosive gases has become an increasingly important area of concern.Take gas-sensitive materials as the core,and on this basis,the development of gas sensors is be used of more and more in the daily life.Therefore,the development of high performance gas sensor has a strong practical significance.In this paper,ZnO gas sensing material is taken as research object,by using first principle method,the simulation calculation on the optimized parameters ZnO crystal properties and Pd doped ZnO materials,gas sensing properties of NO and CO gas adsorbed on ZnO materials and gas sensing properties of NO and CO of Pd doped ZnO materials in the whole experiment is carried out;what's more,the effect of ZnO material loaded with noble metal Pt on gas sensing properties of NO and CO is studied.According to the test on truncation energy and K point,the truncation energy in accordance with accuracy and computational requirements is determined as 420 eV,K point is 4󫶘,error between calculated values for this parameter setting and accepted experimental value is less than 2%.Using the first principle method to simulate Pd doped ZnO,results show that the vast majority of surface Pd doping ZnO is achieved by replacing Zn,meanwhile,the doping causes the electronic structure of ZnO surface changed.Through the establishment of four exponential surface adsorption model(ZnO(110),ZnO(100),ZnO(101),ZnO(001))of Zn O crystal,the analysis of surface energy after structural optimization finds that,ZnO(001)is the most stable index surface,indicating the possibility of ZnO(001)surface exposed on the surface in actual ZnO materials is the best,thus ZnO(001)surface is chosen as the model to study adsorption properties of Zn O.By the adsorption simulation of ZnO(001)model to NO,CO gas,it is found that the adsorption of NO and CO is a spontaneous process,however,the adsorption energy is not high,indicating that the necessary to heat the adsorption material to increase the adsorption effect of the material to NO,CO,this is also consistent with the working temperature of ZnO gas sensor higher than room temperature in actual situation.By comparing the adsorption property of ZnO(001)surface to CO and NO gas,it is fund that NO is more easily adsorbed on ZnO(001)surface,and the working temperature of absorbing NO is also lower than that of CO.From the adsorption simulation of Pd-ZnO(001)model to NO,CO gas,it is found that the adsorption of NO and CO is a spontaneous process,doping Pd in ZnO can effectively improve the selectivity and adsorption of ZnO to NO,and reduce the operating temperature of the ZnO gas sensor at the same time.By comparing the adsorption properties of CO and NO on Pd-ZnO(001)surface,we find that NO is more easily adsorbed on Pd-ZnO(001)surface,and the working temperature required by NO is also lower than that of CO.For ZnO,the doping of Pd can significantly improve the adsorption performance of ZnO to CO and NO,significantly enhance the adsorption and selectivity of ZnO to CO and NO gas,and reduce the operating temperature of ZnO gas sensor.By the adsorption simulation of Pt-Pd-ZnO(001)model with Pt loading to NO,CO gas,it is concluded that the adsorption of NO and CO is a spontaneous process.Loading Pt in Pd-ZnO can reduce the selectivity and adsorption of Pd-ZnO to NO,and improve the working temperature of ZnO gas sensor as well.What's more,by comparing the adsorption properties of CO and NO on Pt-Pd-ZnO(001)surface,it is found that NO is more easily adsorbed on Pt-Pd-ZnO(001)surface.
Keywords/Search Tags:Gas sensor, ZnO, First principle, Noble metal doping, Noble metal loading
PDF Full Text Request
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