Improving The Sensing Properties Of Ln₂O₃Basic Materials By Doping And Surface-decorating

Now, science and technology are developing with a rapid speed beyond our imagination.People are trying kinds of new ways to study the world we are living in. Among them, sensor isan efficient device to help us know the nature better. For example, it can be used to explore theuniverse, detect the industry pollution and raise crop yields, and so on. In a word, we can’t livea happy life without sensors. Among them, gas sensor is a special one that is very helpful to us.An efficient gas sensor can timely detect the toxic and flammable gases such as CH4，HCHOand H2which are harmful to our health and safety. Taking this into consideration, more andmore people concentrate on fabricating new nanomaterials with unique morphology anddevices with special structure. As a member of this field, I spent most of my time studying gassensors based on metal oxide semiconductor nanostructures during the last three years.Firstly, pure In2O3nanofibers were fabricated via an electrospinning method. Thensurface-decorating was used to improve the properties of the pure nanostructures. Pt particleswere successfully used to decorate the pure In2O3nanofibers via a special method. After that,two sensing devices were fabricated using the pure and Pt-decorated nanofibers, respectively.Then we studied their sensing properties to formaldehyde. The concentration was100ppm andthe detecting temperature was from120℃to270℃. The sensitivities of the two devicesincreased with the increasing temperature at the beginning. When the detecting temperaturewas200℃, the sensitivity of the device based on the Pt-decorated In2O3nanofibers reached11, the response time was0.1s and the recovery time was0.2s. When the temperatureincreased from200℃to270℃, the sensitivity decreased with the increasing temperature.As for the device based on the pure In2O3nanofibers, the sensitivity reached the highest whenthe temperature was230℃,and the value was3. When the temperature increased from230℃to270℃, the sensitivity of the device based on the pure In2O3nanofibers decreasedwith the increasing temperature. It was found that the sensor based on the Pt-decorated In2O3nanofibers was more sensitive to HCHO compared with the one based on the pure materials. Secondly, pure and V-doped In2O3microspheres were prepared by a hydrothermal method.To get the V-doped In2O3microspheres, Vanadium triisopropoxy oxide (C9H21O4V) was addedto the precursor liquid. Through series of characterizations, it proved that we got In2-xVxO3solid solution. Two sensing devices were fabricated using the pure and V-doped In2O3microspheres, respectively. Then we studied their sensing properties to acetone. Theconcentration was100ppm and the detecting temperature was from140℃to280℃. It wasfound that the sensor based on the V-doped In2O3microspheres was more sensitive to acetonecompared with the one based on the pure materials. When the temperature increased from140℃to200℃, the sensitivity of the device based on the V-doped In2O3microspheresincreased with the increasing temperature. When the detecting temperature was200℃, theresponse time was1.5s, the recovery time was0.7s and the sensitivity was five times higherthan the device based on the pure In2O3microspheres. When the temperature increased from200℃to280℃, the sensitivity of the device based on the V-doped In2O3microspheresdecreased with the increasing temperature. This phenomenon proved that200℃was theoptimum working temperature of the device based on the V-doped In2O3microspheres.