Application Of Semiconductor Gas Sensors Based On SnO₂ Nanomaterials With Different Morphologies And Sensitizers In The Rapid Detection Of Food Safety Hazards

Food safety is the foundation of human health.Timely detection and prevention of food safety hazards is the top priority for ensuring food safety.In recent years,food safety incidents caused by chemical and biological food safety hazard factors have caused severe influences,such as pesticide and veterinary drug residues,heavy metal pollution,illegal additives,foodborne pathogens,viruses,parasites,etc.Most pesticides are bio-accumulative.And due to the abuse or unreasonable use of them,incidents of excessive pesticide residues in food occur frequently.Once the pesticide residues in food enter the human body,can seriously damage the human digestive system,circulatory system,and nervous system.Therefore,the problem of pesticide residues in food is currently the top priority in the detection of chemical food safety hazards.Meanwhile,food borne pathogens are widely distributed and highly pathogenic,which is one of the most dangerous food hazards.Millions of people around the world get sick every year due to eating food contaminated by food borne pathogens.Therefore,real-time monitoring of foodborne pathogens is of great significance to ensure food safety.In order to timely detect and deal with these potential food safety threats,it is of great urgence to develop simple,fast,and real-time detection technology for food safety hazards.Gas sensors based on the metal oxide semiconductor show great advantages in highly sensitive detection of flammable,explosive,toxic and harmful gases generated or existing in industrial production,environment,and human life,due to its simple preparation,portable equipment,low cost,simple operation,and the advantages of reusable.In this study,Sn O₂ nanomaterials with different morphologies and sensitizer were synthesized from two aspects of morphology control and doping sensitization to develop semiconductor gas sensors for rapid and sensitive detection of food pesticide residues and food borne pathogens.What's more,the relationships between the structure and morphology of the sensing materials and their sensing properties were also investigated.The results can be summarized as follows:1.Synthesis of Pt doped Sn O₂ with different morphologies for rapidly detection of food pesticide residues.In this chapter,Sn O₂ nanomaterials with different morphologies?nanospheres,hollow nanospheres,nanoflowers?were prepared by simple hydrothermal method through controlling the p H,reaction temperature and reaction time.Sn O₂ nanobox was prepared by coprecipitation and selective etching with hydrochloric acid.The structure and morphology of the synthesized materials were characterized by X-ray powder diffraction?XRD?and scanning electron microscopy?SEM?.The results show that the Sn O₂ nanomaterials with different morphologies have regular morphology and good monodispersity.The effect of different morphology on the gas sensing performance of Sn O₂ were studied.The results show that the semiconductor gas sensor based on Sn O₂with different morphology have the advantages of high sensitivity,superb long-term stability,and good response-recovery to acephate at 300?.In addition,gas sensor based on Sn O₂ nanobox show better sensitivity,which is mainly due to the large specific surface area of hollow structure,which can provide more reaction points for gas molecules and conducive to the improvement of sensitivity.It's worth mentioning that,gas sensors based on Sn O₂ nanobox have good reproducibility and stability,and have a broad application prospect in the rapid and accurate detection of acephate pesticide residues.2.Controlled synthesis of Pt doped Sn O₂ hollow nanospheres for highly selective and rapidly detection of 3-hydroxy-2-butanone biomarker.Listeria monocytogenes has been recognized as one of the extremely hazardous and potentially life-threatening food-borne pathogens,its real-time monitoring is of great importance to human health.Herein,a simple and effective method based on platinum?Pt?sensitized tin dioxide?Sn O₂?semiconductor gas sensors has been proposed for selective and rapid detection of Listeria monocytogenes.Sn O₂ hollow nanospheres with different dose of Pt?0.08%wt-0.48%wt?have been synthesized successfully through a robust and template-free approach and used for the detection of3-hydroxy-2-butanone biomarker of Listeria monocytogenes.The morphological characterization showed that Pt was successfully doped into Sn O₂ hollow nanospheres and dispersed uniformly.Gas sensitivity test results showed that the doped of Pt significantly increased the response of Sn O₂ nano-hollow spheres to3-hydroxy-2-butanone and improved the selectivity.Remarkably,sensors based on Sn O₂ mesoporous hollow nanospheres with 0.16 wt%Pt dopant exhibit excellent sensitivity?Rair/Rgas=48.69?and short response/recovery time?11/20 s,respectively?to 10 ppm 3-hydroxy-2-butanone at the optimum working temperature.Moreover,0.16wt%Pt doped Sn O₂ gas sensors also present particularly low limit of detection?LOD=0.5 ppm?,superb long-term stability and prominent selectivity to3-hydroxy-2-butanone.Such a gas sensor with high sensing performance foresees its tremendous application prospects for accurate and efficient detection of foodborne pathogens for the food security and public health.