Research On The Surface,interface Design Of Ammonia Gas Sensor Based On WO_X System

Since the industrial revolution,human productivity has developed rapidly,greatly improving human production efficiency and human life.However,with the development of science and technology,serious environmental pollution problems have been caused.So far,air pollution has developed into one of the four major environmental hazards,endangering human health and public safety.Among them ammonia gas?NH₃?is a kind of human industrial emission of the representative of the exhaust gas,colorless and transparent,with a strong volatile.Contact with trace amounts of NH₃ briefly,that will cause human discomfort,serious disease and even death.In addition to human beings,NH₃ also causes great harm to animals,and is a potential threat to animal husbandry.Therefore,in order to accurately avoid the damage of NH₃ to all aspects,the timely monitoring and detection of NH₃,as well as the optimization and improvement of NH₃ sensors,are of great significance to human society.In recent years,many attempts have been made to improve the performance of gas sensors.In this paper,starting from the manufacturing surface defects,combined with the construction of heterojunction,the W₁₈O₄₉ nanowire material was processed and applied to the detection of NH₃.The main research contents are as follows:?1?WCl₆ was used as the raw material,W₁₈O₄₉ nanowires were prepared by hydrothermal method,and surface oxygen defects were manufactured by hydrogen?H?and argon?Ar?plasmas treatments.Aniline monomer was used as the raw material,combined with nanowires with surface defects that had been treated by plasma.W₁₈O₄₉-PANI core-shell structure was formed by polymerization and growth process.The thickness of PANI shell was controlled by controlling the ratio of aniline monomer in nanowires.Finally,the electrode material treated by oxygen?O?plasma was immersed in the solution,and adsorbed to form a film on the electrode to construct the sensor.XRD,SEM,TEM,ESR and XPS were used to analyze the characteristics of the defect and its structure,and then the NH₃ response-recovery,stability and selectivity were tested.The effects of surface defects,heterojunction and composite structure on performance were analyzed.?2?W₁₈O₄₉ nanowires were grown directly on the electrode to overcome the problem of too large contact resistance and low conductive efficiency caused by the smear adsorption forming sensor.The conducting end of the electrode was treated with O plasma in advance,WCl₆ was used as the raw material and treated electrodes were added to the solution by hydrothermal method to form a sensor on which the nanowire was grown,instead of the material being made and then physically coated.Sensors that grow nanowires already respond at room temperature,and then trested by H and Ar plasmas to create rich defects on the surface of nanowires.XRD,SEM,XPS and other characteristics were used to analyze the characteristics of defects,and then the performance was tested.The results show that the surface defects produced by plasma treatment can improve the performance greatly.?3?WCl₆ was used as the raw material to form W₁₈O₄₉9 nanowires by hydrothermal method.The W₁₈O₄₉-WO₃ heterojunction was formed by oxidation sintering.XRD analysis shows that the heterostructure is successfully constructed,and the difficulty lies in controlling the ratio between the two phases.SEM shows that the ratio between the two phases is different,which has a great influence on the overall morphology of the sample.Through the performance test of NH₃,compared with pure phase W₁₈O₄₉,the response temperature is lower and the response level is higher,realizing the effect of heterojunction.