Synthesis And Gas Sensitive Properties Of Ni Or Zn-based Materials Combined With Graphene

Environmental pollution caused by the emission of waste gas from industrial manufacture and daily life and the leakage of poisonous,harmful,flammable and combustible gases,which impact on the health and safety of lives and properties seriously.Gas sensor,as the instrument to detect species and concentrations of gases,has been widely researched and applied.The development of gas sensing materials,the core of gas sensor,is the focus in the felid of gas sensor.So far,many kinds of gas sensing materials have been to have electrochemical performance,but few materials with excellent electrochemical performance were reported to be used as gas sensors.Bimetallic compounds(AB2X4)have good performance,and NiCo2S4 is a common material used in the felid of electrochemistry.Graphene-based materials have the advantages of reducing working temperature and response/recovery times when it is used in the felid of gas sensors.Therefore,we design to synthesize materials based on NiCo2S4,which are used as gas sensing materials and compared with ZnFe2O4/rGO in this paper.In this paper,three morphologies of cubic NiCo2S4 materials were synthesized by a simple solvothermal mothed.The different morphologies were controlled by adding various solvents and metal salts.The analysis result of N2 adsorption desorption test shew that the specific surface area of hollow sphere-like NiCo2S4 was larger than that of solid sphere-like and flower-like NiCo2S4.NiCo2S4 was used as gas sensing material exploratory and hollow sphere-like NiCo2S4 displayed the best gas sensitive properties to 100 ppm ethanol,such as high response value,good selectivity and stability.In addition,the formation mechanisms of three morphologies of NiCo2S4 materials were proposed.Graphite oxide was prepared by modified Hummers method in this paper,and flower-like NiCo2S4/rGO nanosheet composite was synthesized by a simple solvothermal method subsequently.The results of SEM revealed flower-like structure was self-assembled by nanosheets and the morphology of the product,when the addition of graphite oxide was 20 mg in the reaction,was the most uniform.From the analyses of gas sensing test,we knew the gas sensing properties of NiCo2S4/rGO composite is much better than pure NiCo2S4.The optimum working temperature of NiCo2S4/rGO was about 100 ? and the response value to 100 ppm ethanol was 2.66.ZnFe2O4/rGO was successfully prepared by solvothermal method,and we put forward the possible synthesis mechanism which was consisted of the reduction of graphite oxide,the nuclear,growth and self-assembly of ZnFe2O4 particles and Ostwald ripening process.The morphology of ZnFe2O4/rGO with the addition of graphite oxide about 20 mg(ZFOC-20)was consisted of cubic spinel type ZnFe2O4 with a diameter of about 250 nm and rGO nanosheets.The specific surface area is 116.54 m2/g,and the pore volume and average pore size were 0.23 cm3/g and 17.04 nm,respectively.That was to say,the material of ZFOC-20 belonged to the category of mesoporous materials.ZnFe2O4/rGO composite with the addition of graphite oxide about 20mg(ZFOC-20)had the best performance,whose response value was 57%to 10 ppm acetone at a temperature of 135 ?.