Preparation Of Metal Oxide Semiconductor With PtAg、PtPd Modification And Study On The Gas Sensitivity

At present,human society is in an important stage of transformation from an industrial society to an intelligent society.With the advancement of modern industrialization,the construction of an environment-friendly society has far-reaching significance for the transformation of human society and green and sustainable development.However,with the rapid development of industrialization,environmental problems such as air pollution brought by the discharge of a large number of toxic and harmful gases have caused serious harm to people’s daily life.Therefore,metal oxide semiconductor（MOS）gas sensors have ushered in unprecedented development opportunities.This paper mainly studies the synthesis method of PtAg/PtPd and the modification method on the surface of metal semiconductor oxide（MOS）,and explores the sensitization mechanism of PtAg/PtPd on MOS material through gas sensing performance test.The specific research contents are as follows:1.WO₃,Pt@WO₃,Ag@WO₃ and PtAg@WO₃ nanomaterials were prepared by hydrothermal method and chemical reduction method,and a series of characterizations were carried out on the prepared materials.The gas sensing performance test results show that the PtAg@WO₃ sensor exhibits a good response to 100 ppm CO.Compared with the WO₃ sensor,the response value is increased by about 2.79 times,and the working temperature is reduced by 20°C,and the adsorption performance of CO on the（111）crystal plane of Ptand Ag is studied by first-principles calculations.The enhanced CO gas sensing performance of PtAg@WO₃ is mainly attributed to the chemical sensitization of Pt,the electronic sensitization of Ag and the synergistic effect between them.2.WO₃ and Pt@WO₃,Pd@WO₃,PtPd@WO₃ composites were synthesized by solvothermal method and in-situ reduction method.The gas sensing performance test results show that the response of the PtPd@WO₃ sensor toward 10 ppm H₂S at a lower temperature（120℃）reaches 196.188,which is 49.47 times that of the initial WO₃response value.The detection limit reaches ppt level（as low as 506 ppt）.This is mainly attributed to the increase of oxygen vacancies in the PtPd@WO₃ composites,the overflow effect of Pt,the electron sensitization of Pd,and the synergistic effect between Ptand Pd.3.PtPd bimetallic nanoparticles were prepared by chemical reduction method.Then,PtPd-Bi₂Mo O₆ composites with different PtPd contents were prepared by solvothermal method.TEM analysis showed that the size of PtPd nanoparticles was about 1-3.7 nm.Sensitivity test results for CO gas show that 1.5%-PtPd-Bi₂Mo O₆ has excellent selectivity and good moisture resistance to 200 ppm CO at 360℃,and has a short response（12 s）and recovery（12 s）time.The first-principles calculations show that the enhanced gas sensing properties of the composites are mainly attributed to the strong interaction between bimetallic PtPd and Bi₂Mo O₆.