| Respiratory analysis has great potential in treatment monitoring and disease diagnosis.The concentration of acetone in the breath of diabetic patients is higher than that of healthy people,so we can analyze whether people have diabetes by detecting the concentration of acetone.Among various metal oxide semiconductor(SMO)materials for acetone detection,WO3 is considered to be one of the most promising materials for acetone detection due to the strong interaction between monoclinic WO3 and polar acetone.However,the composition of respiratory gas is complex,and the selectivity of WO3 based acetone sensor is poor.Among the strategies to improve the selectivity,noble metal nanoparticles have great advantages in improving the selectivity of acetone gas sensor.However,noble metal nanoparticles are easy to agglomerate at higher working temperature,which leads to the decrease of the utilization rate of noble metal atoms.Therefore,the problem of noble metal agglomeration can be solved by combining with the materials with 3DOM structure,and the selectivity to acetone can be improved.In this paper,we prepared AuPd alloy and Au25 nano cluster loaded 3DOM WO3 materials,analyzed the prepared gas sensing materials through a series of characterization,and studied the sensing performance of acetone gas.In addition,the sensing mechanism is also discussed.The specific conclusions are as follows:(1)Firstly,3DOM WO3 was synthesized by PS microsphere template method,and then different amounts of AuPd alloy loaded 3DOM WO3 nanomaterials were synthesized by NaBH4 reduction method.The three-dimensional ordered macroporous structure was observed by SEM,and the synthesis and particle size of AuPd alloy was 7.57 nm by TEM.The results of acetone gas test show that the optimum working temperature of the material is 300℃,which is lower than that of pure 3DOM WO3.In addition,the response value of 1 wt%AuPd/3DOM WO3(AuPdW)to 2 ppm acetone is 12,which is 4 times that of pure 3DOM WO3.More importantly,the response value of the sensor to 100 ppb acetone can still reach 1.5.In addition,the rapid response/recovery time(5 s/3 s)may be attributed to the synergistic effect of 3 DOM structure and AuPd alloy.The synergistic effect of electron sensitization and chemical sensitization of AuPd alloy is the main reason to improve the performance of acetone gas sensing.On the other hand,the steric hindrance effect of the 3DOM structure prevents the agglomeration of the AuPd alloy at the working temperature,thus obtaining good long-term stability.(2)Firstly,Au25 nanoclusters were prepared by NaBH4 reduction method,and then the different amount of AU25 nanoclusters were loaded with 3DOM WO3 nanomaterials.The results of TEM show that the size of Au25 nanoclusters is 1.2 nm.The results of XPS showed that the load of Au25 nanoclusters increased the adsorption oxygen of the materials.The results of material test show that the optimum working temperature of the material is 370℃,which is lower than that of pure 3DOM WO3.In addition,the load of Au25 nanoclusters was optimized,which indicated that the response value of 3DOM WO3(2AuW)to 10 ppm acetone gas was 26,about 5.4-19.3 times of other gases.The synergistic effect of electron and chemical sensitization of Au25 nanoclusters is the main reason to improve the gas sensing performance of acetone.In addition,2AuW has a fast response recovery time(4 s/8 s)and long-term stability of 8 weeks,mainly due to the spatial potential resistance effect of 3DOM structure on Au25 nanoclusters,which increases the atomic utilization of Au,thus improving the sensing performance of acetone gas. |
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