Gas Sensor Based On Hierarchical Indium Oxide Structure

In recent years, the fog and haze of our country continues have seriously affected the health ofpeople. How to perform real-time monitoring of pollution sources and on-line monitoring of thequality of atmospheric environment is an urgent problem need to address. The research anddevelopment of high sensitivity, high selectivity, and high reliable gas sensor becomes veryimportant.NO2and O3is a typical atmospheric pollutants, NO2and O3real-time online monitoring of airquality forecasting and atmospheric research in the atmosphere is an urgent problem to address.This paper mainly for the two typical real-time monitoring of air pollution gases, improve thesensitive material from the micro-nano structures start on the order of NO2and O3ppb sensitivity,detection limit and selective detection. After making a lot of basic research and pre-researchliterature, we discover that compared to several other common semiconductor oxide, In2O3hasexcellent gas sensing characteristics to NO2and O3. In2O3has greater conductivity, is conducive tobuilding simple sensing system.This paper aims to study the structure of In2O3hierarchical design, fabrication and gas sensingcharacteristics. By adjusting the hydrothermal synthesis conditions to regulate the morphology ofindium oxide. Mainly by change the reaction temperature, select the precipitating agent, optimizedprecipitant concentration of surfactant screening. Adjustment indium oxide’s morphology andmicro-nano structure by the above method, and then study the gas sensing characteristics associatedwith the law of the morphology and micro-nano structures. The main work includes the followingaspects:1. Hierarchieal In2O3nanomaterials included nanosheets, multi-level, flowerlike microspheres,star-shaped flowers and urchin-like with structure Uniform and high dispersity were synthesied bysimple hydrothermal and solvothermal methods.The as-synthesized samples were characterizedusing X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electronmicroscopy (TEM), Brunauer-Emmett-Teller (BET).2. The gas sensing properties of In2O3with different structure and morphology were measuredby mixing detected gas and air in static state. The test results showed that multi-level flowerlikeIn2O3have higher gas sensitivity than In2O3nanosheets.3. The star-shaped flower-like In2O3has high sensitivity and best stability to NO2at roomtemperature. Urchin-like In2O3has high sensitivity and fast response/recovery characteristics to O3.4. The results of testing gas sensing properties showed that In2O3gas sensor has lower power consumption or operation temperature.In this paper, micro-and nano-structures for different indium oxide growth mechanism andsensitive mechanisms were studied. Found that the morphology and micro-/nano-structure ismainly determined by the In2O3preparation temperature, surfactant type, amount and type ofprecipitant and solvent species. Sensitizing effect of micro-and nano-structures can be attributed toits large specific surface area and good permeability, because these structural features cansignificantly improve the recognition sensors and sensitive body efficiency.