Preparation Of Ag-decorated G-C₃N₄/Metal Oxide Composite And The Gas Sensing Properties

Gas sensors play an important role in air quality monitoring,and detection of flammable,explosive,toxic and harmful gases.Metal oxide gas sensors(MOGS)have received extensive attention due to their high sensitivity,wide measurement range,fast response/recovery time,long life,and low cost.Common MOGS materials include Zn O?In₂O₃?Sn O₂??-Fe₂O₃?Mo O₃ and WO₃,etc.However,sensors based on these materials usually have high operating temperatures.As a new type of photocatalytic material,g-C₃N₄ has great application prospects in sensors due to its good photosensitivity and electrical sensitivity.The gas-sensitive response of g-C₃N₄ and metal oxide(MO)composites is higher than pure g-C₃N₄ and MO,but the problem is that the working temperature is relatively high.But the working temperature is still relatively high.Based on the existing research reports,by loading Ag to improve the response of the two composite materials,g-C₃N₄/?-Fe₂O₃ and g-C₃N₄/WO₃ to volatile organic compounds(VOC),and reduce the working temperature of the gas sensor.The main content and results of this work are as follows:(1)The g-C₃N₄ and?-Fe₂O₃ nanosheets are composited by high-temperature annealing and calcining,and then a certain amount of Ag is incorporated into the composite material by solvothermal method.We prepared g-C₃N₄/?-Fe₂O₃ composite materials decorated with Ag in different proportions(2%,6%,10%).Their structure and morphology were analyzed by XRD,SEM,TEM,and XPS characterization methods.And explore the influence of temperature and concentration on their gas sensitivity performance.Among them,the 10%Ag-decorated g-C₃N₄/?-Fe₂O₃ nanocomposite exhibits excellent gas-sensitive response to ethanol at 150?,the response to 50 ppm ethanol reaches 12.53,and the response/recovery time is 3.75 s/44.29 s.And after 5 cycles,the gas sensor showed stable response.Therefore,the g-C₃N₄/?-Fe₂O₃composite material decorated with Ag nanoparticles can effectively improve the gas sensitivity and reduce the working temperature.(2)The g-C₃N₄ and WO₃ nanosheets are composited by high-temperature annealing and calcining,and then a certain amount of Ag was incorporated into the composite by solvothermal method.We prepared g-C₃N₄/WO₃ composite materials decorated with Ag in different proportions(2%,6%,10%).Their structure and morphology were analyzed by XRD,TEM and XPS and other characterization methods.And explore the influence of temperature and concentration on their gas sensitivity.Among them,the 10%Ag-decorated g-C₃N₄/WO₃nanocomposite exhibits excellent gas-sensitivity response to acetone at 150?,the response to50 ppm acetone reaches 3.03,and the response/recovery time is 47.71 s/74.89 s;6%Ag decorated g-C₃N₄/WO₃ nanocomposite exhibits excellent gas-sensitive response to acetone at300?,the response to 50 ppm acetone reaches 3.51,and the response/recovery time is 4.38 s/19.97 s.And after 5 cycles,the gas sensor showed stable response.Therefore,according to the working temperature of the sensor,choose different proportion of Ag decorated g-C₃N₄/WO₃sensors.