Research On The Gas Sensitivity Of Au Modified SnS₂ Nano-Flowers Based Materials

Sensors can realize the perception and acquisition of information such as the external environment.With the rapid development of the Internet of Things and artificial intelligence,sensors are playing an increasingly important role in the Internet of Things and artificial intelligence.The traditional metal oxide semiconductor gas sensing technology has been relatively mature.However,there are oxygen vacancies on the surface of metal oxides,which are easy to interact with the external environment,resulting in shortcomings such as poor selectivity and stability of the sensors.And the working temperature is high,the power consumption is large,and it is not easy to integrate and miniaturize.Metal sulfide is a layered material with a hexagonal crystal structure,which has excellent properties such as large specific surface area,and is of great significance in the research of low temperature or room temperature gas sensing.Therefore,this paper uses metal sulfide as the core material to further improve the sensor performance by adjusting the material morphology,noble metal modification and forming a heterojunction with metal oxide,and develop a gas sensor with superior performance.The research results of this paper are as follows:1.SnS₂nano-flowers were synthesized by solvothermal method as the main material,and the reaction time of the solvothermal process was controlled to optimize the morphology of the material.The SEM characterization results showed that the hydrothermal time was 16 h/SnS₂material was more uniform and orderly.Flower-like structure,and its gas sensitivity shows that the response value of 16 h is the best.Its response value to 8 ppm NO₂at 120?reaches 15.3,which is about twice the response value of other material sensors obtained by hydrothermal time.This may be due to the larger specific surface area of the material with a hydrothermal time of 16 h.But its response/recovery time is long.2.The surface of SnS₂nano-flower was modified by reducing HAucl₄to Au nanoparticles by chemical precipitation method to improve the gas sensitivity of the material.The gas sensitivity of materials with different gold doping ratios was tested.When the content of Au NPs is 0.03%,the best working temperature of the sensor is100?,and the response of the sensor to 8 ppm NO₂reaches the maximum 14.5 at 100?.And the recovery time is 127.6 s/255.2 s,which is about half of the SnS₂sensor.This may be due to the catalytic effect of Au nanoparticles and the Schottky contact formed between Au and SnS₂.However,the improvement of the response of the gold doping to the material is not obvious.3.The SnS₂material is oxidized in situ to obtain SnS₂/SnO₂material,and then the Au@SnS₂/SnO₂ternary composite is obtained by chemical precipitation method modifying on the surface of the SnS₂/SnO₂to further improve the gas sensitivity of the material.By testing the sensing properties of materials that are oxidized and then doped with gold and doped with gold and then oxidized,it is found that the order of in-situ oxidation and gold doping has no effect.The gas sensitivity of the material with different oxidation time was tested,and it was found that when the oxidation time was 1 h,the sensor had the best sensing characteristics.When the oxidation time is 1 h,the optimal working temperature of the sensor is 80?,the sensor's response to 8 ppm NO₂at 80?reaches a maximum of 22.3,and the response and recovery time is 174 s/359.6 s,while the SnS₂sensor is at 80?The response below is 8.1,the response and recovery time are435.2 s/798.4 s,and the gas sensitivity is significantly improved.