The Effect Of Doping To The Gas Sensing Properties Of Gas Sensors Based On CdS And In₂O₃

In recent years,people's safety of life and property were threatened by the greenhouse effect,ozone hole,which were caused by environmental damage,mine accident,household decorating/food security.Owing to the advantages of small volume,low-cost,fast response and recover speed,high sensitivity,low energy consumption and for mass production,gas sensors were widely used in the fields of portable and fit for mass production.Although we had made a great progress on the research of gas sensor,even some gas sensors based on the metal oxide semiconductors had reached the commercial level for qualitative and quantitative measurement.However,there exist a lot of problems,such as low response,slow response and recovery speed,poor selectivity,etc,for the most of gas sensors based on semiconductor.Therefore,solving the above problems and improving the gas sensing properties to meet the need in the fields of atmospheric air monitoring,coal mine/household/food security,medical diagnosis,military,etc,had been a hot topic in the field of gas sensor research.CdS and In₂O₃ nanomaterials had been synthesized via simple hydrothermal process.In order to research the effect of transitional element doping to the semiconductor,some transitional element had been doping in CdS and In₂O₃ nanomaterials.the main content is as follows:?1?Urchin-like hierarchical Zn doped CdS powders were successfully synthesized via simple one-pot hydrothermal process,which consist of a lot of one-dimensional structural unit?nanorod?.Gas sensors were fabricated based on the undoped and Zn doping CdS nanomaterials and the gas sensing properties to ethanol were tested.The best operating temperature of these gas sensors was 225?.They had a good selectivity to ethanol.In this temperature,the sensitivity to 100 ppm ethanol of the gas sensor based on Zn doped CdS nanospheres is 27.2,which is 4.2 times to the undoped CdS nanospheres.The former has fast response and recover speed,the response time and recover time were 1 s and 8 s,respectively.Because of some intrinsic defect in the metal oxide nanomaterials,some gas sensors based on the metal oxide semiconductor can not meet the need in some field.Thus,studying some new nanomaterials will be a good topic in gas sensor researching.?2?A series of In₂O₃?undoped,1 at%,2 at%,3 at%Sm doping?nanospheres were synthesized via one-pot hydrothermal process and gas sensors based on the above-mentioned samples were fabricated.The gas sensor based 1%Sm doping In₂O₃nanospheres has a good selectivity to 100 ppm acetone,the sensitivity was 23.7,which is 2.2 times to the gas sensor based on undoped In₂O₃ nanospheres in the best operating temperature 275?.The response and restore characteristics changed hugely with the change of the operating temperature.It had very slow response and recover speed in 200?,the response and recover time were 17 s and 420 s,respectively.When the temperature rises to 275?,the response and recover time were 4 s and 152 s,respectively.The above results indicate that transitional element doping is a effective method to improve the gas sensing properties of the nanomaterials.