Study On The Preparation And Gas Sensing Properties Of Metal Oxide Semiconductor（Co₃O₄）

Based on metal oxide（MOS）p and n type semiconductor sensors are widely used in air detection,toxic and harmful gases and so on.These devices have the advantages of high sensitivity,low cost,easy to use and easy to carry.The gas sensing performance of the gas sensor is highly related to the structural characteristics of the sensing materials.The preparation of high performance gas sensitive materials has always been the focus of the semiconductor gas sensor.In this paper,the preparation of p type gas sensitive material four oxidation three cobalt（Co₃O₄）is discussed,and its gas sensitive properties are improved by adjusting the morphology structure and surface recombination.The main contents are as follows:The Co₃O₄microspheres assembled by single crystal porous nanosheets were synthesized through a simple solvothermal reaction and subsequent oxidation process.The relationship between time and characteristics in different growth stages was characterized,and interesting dynamic growth process was discussed.Benefiting from the structural stability of single crystal nanosheets,the hierarchical porous structure of Co₃O₄is not destroyed by mechanical and thermal stress during sensor fabrication.The prepared porous Co₃O₄microspheres showed excellent gas sensing performance for xylene,and the response to 100 ppm xylene was up to（R_g/R_a=74.5）,the optimum working temperature 150 ^oC could greatly reduce the power consumption.Due to the stability of single crystal nanoscale,it has excellent long-term stability and two months’bias（less than 6%）.In addition,it has high gas selectivity and low concentration detection limit.Inspired by the super“receptor-sensing-response”structure of the Venus fly trap,we designed a gas composite material that one dimensional Zn O nanorod’trigger’was grown on the"channel"surface of a single crystal porous Co₃O₄nanoscale sensor.It is found that the response of the Zinc Oxide/Cobalt to ethanol is high（R_a/R_g=125）,which is superior to the individual Co₃O₄（R_a/R_g=1.43）and Zn O（R_a/R_g=15）.It provides an important material design guidance for the development of high performance gas sensors.