Synthesis And Gas Sensing Performance Of Zinc Metastante Materials

Gas sensor plays an important role in monitoring many volatile organic compounds(VOCs)gas due to its advantages of low manufacturing cost,small size and low energy consumption.As the most important component of gas sensor devices,sensor material directly determines the sensing performance of the sensor.Therefore,the improvement and optimization of gas sensor has become a hot topic in the field of gas sensor research.In this paper,ZnSnO₃/rGO,Bi-ZnSnO₃/CuO and Ce-ZnSnO₃composites were successfully synthesized by doping reduced graphene oxide(rGO),Bi,CuO and Ce in ZnSnO₃ matrix to modify ZnSnO₃ material.The structure,micro-morphology,specific surface area and pore size and valence composition of the composites were characterized by the X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Brunauer-Emmett-Teller(BET)and X-ray photoelectron spectroscopy(XPS),respectively.These measures obviously improved the problems of high optimal operating temperature and low selectivity of matrix material in practical application.In addition,the corresponding gas sensing mechanisms were analyzed according to the above characterization results.The main research results are as follow:ZnSnO₃/rGO composite was successfully prepared by hydrothermal method.The results showed that rGO and ZnSnO₃ only physically combined with each other and formed p-n heterojunction at their interface.The composite had a hierarchical,porous structure and larger specific surface area.When the doping content of rGO was 4 wt%,the composite had the best recognition ability for acetone gas,the lowest dependence on working temperature,and excellent long-term stability.These excellent properties make it a reliable sensing material for acetone gas detection.The improvement of sensing performance of ZnSnO₃/rGO was due to its special structure,large specific surface area and p-n heterojunction.Bi-ZnSnO₃/CuO composite was successfully prepared by in-situ precipitation method.The results showed that the composite was mainly composed of lamellar CuO and cubic ZnSnO₃,which formed p-n heterojunction at the interface.The surface of the composite had abundant porous structure and large specific surface area.These characteristics obviously improved the sensing properties of the matrix material for acetone gas.This mainly included that the optimal working temperature of Bi-ZnSnO₃/Cu O(Bi:3.5 wt%,Cu O:10 wt%)composite decreased by 50?,and the response value to acetone gas with concentration of 100 ppm increased by 5.59 times,while the response/recovery time was only 4 s/12.5 s.At the same time,it had the advantages of selectivity and repeatability.Ce-ZnSnO₃ composite was successfully prepared by hydrothermal method.The results showed that the composite had a two-dimensional lamellar structure and the doping of Ce promoted the formation of more oxygen defects.The results showed that the response of Ce-ZnSnO₃ composite(0.5 at%)in the gas sensing test as a sensing material to 100 ppm n-butanol gas at 350?was more than 10 times higher than that of pure ZnSnO₃(245.18),and the response/recovery time was only 6 s/26 s.The enhanced gas sensing properties of the composites can be attributed to the formation of a large number of oxygen defects.At the same time,it was found that with the further increased of Ce content,the gas sensing properties of the composites began to decline,because of more Ce³⁺was transformed into Ce⁴⁺at high temperature,which consumed a lot of oxygen vacancies.