Study On Gas Sensing Performance Of Cs_xPb_yBr_z/ZnO Composite Structures

Nitric oxide is a harmful gas,usually from the exhaust gas emitted by automobiles and industrial combustion equipment,which not only causes acid rain and damages the ozone layer,but also causes damage to the human nervous system.Therefore,highly sensitive detection of nitric oxide is important to the protection of the environment and human health.Gas sensor is one of the most commonly used methods to achieve this purpose,especially metal oxide semiconductor gas sensor.Among the metal oxides,zinc oxide（ZnO）as a gas-sensitive material has received extensive attention and research due to its simple synthesis process,good chemical stability,and high sensitivity.However,its high operating temperature（>150℃）not only causes high energy consumption,but also has potential risks in the presence of flammable and explosive gases.Therefore,reducing the operating temperature of the ZnO-based gas sensor is crucial.The results of the research reports show that ZnO compounded with other semiconductors to form a heterojunction can effectively reduce its operating temperature and improve its response.It is an ideal effective method for obtaining low-temperature high-sensitivity sensors.In recent years,a new type of material,metal halide perovskite,has shown gas sensitivity at low temperatures,but with unsatisfactory sensitivity.Therefore,it is considered to combine it with ZnO to obtain a low-temperature and high-sensitivity nitric oxide gas sensor.In this work,CsPbBr₃ and CsPbBr₃/Cs₄Pb Br₆ are combined to ZnO to form a gas sensor,and study its gas-sensing performance to obtain a low-temperature and high-sensitivity nitric oxide sensor.The specific research content is as follows:1.ZnO nanorods were prepared in growth solutions at concentrations of 15mmol/L,40 mmol/L and 50 mmol/L,respectively.CsPbBr₃ was synthesized by supersaturation recrystallization and coated on ZnO nanorods to form the sensor.The results showed that the working temperature of ZnO was 150°C,the response of zinc oxide（15 mmol/L）to show a response of 3.2 to 5 ppm nitrous oxide gas,and the working temperature of CsPbBr₃/ZnO was 100°C,CsPbBr₃/ZnO（15 mmol/L）showed a response of 10.4 to 5 ppm nitric oxide gas.By comparison,it is found that the addition of CsPbBr₃ not only reduces the optimal working temperature of ZnO to nitric oxide gas but also improves the response.2.The CsPbBr₃/Cs₄Pb Br₆ solution,consisting of large particles of Cs₄Pb Br₆ and small particles of CsPbBr₃,was synthesized by mixing lead bromide and cesium bromide in a molar mass ratio of 1:1 using the supersaturation recrystallization method and coated onto ZnO nanorods and annealed to obtain gas-sensitive devices.The gas sensitivity test results show that the operating temperature of CsPbBr₃/Cs₄Pb Br₆/ZnO（20 mmol/L）is 50℃,and the response to 100 ppm nitric oxide gas is 2296.The sample has a low detection limit,good repeat stability and excellent selectivity.CsPbBr₃,Cs₄Pb Br₆ and ZnO form a double heterojunction,which effectively reduces the operating temperature and improves the response.As a result,nitric oxide detection at near room temperature is realized.