Nano Self-Assembly And Its Application In Gas Detection

Solid colorimetric sensing is an important gas detection method with the characteristics of visualization,convenience,rapidity,and simplicity,and has shown great application prospects in food,life health,industrial waste gas,and agricultural pollution detection.Traditional colorimetric indicators have the advantages of mature colorimetric mechanisms and good stability,but are difficult to meet the requirements of ultra-trace and high sensitivity for specific gas molecules,which has become the obstacle to their further development.In this study,hydrogen sulfide gas molecules were used as the detection object.By redesigning the lead acetate-based sensitive material,we developed a lead metal-based metal-organic framework material with micro-pores and constructed a mesoporous material through competitive coordination strategy.Based on this,we constructed pores of different sizes using a template method based on polystyrene microspheres and evaluated the effect of the above materials on hydrogen sulfide gas detection.Finally,we selected the optimal material for monitoring the production and disappearance of hydrogen sulfide gas.By comparing the gas sensing performance of different-sized pores,it was found that the confinement effect of the nanocavity was conducive to enriching the substrate and improving the local concentration,and the multi-level pore-penetrating channel was conducive to reaction and mass transfer,improving the contact efficiency between the substrate and the sensor.In addition,by adjusting the pore size of the large pore structure,it was found that the 400 nm P-MOFs had the best detection effect,and the detection limit reached 40 ppb,which may be due to this structure satisfying the Henry’s law.Finally,the preferred 400 nm P-MOFs colourimetric sensor prepared in this paper was used to detect food freshness.Since the sensor does not need to directly contact the food during use,but reacts with the H₂S generated by food decay to produce a signal,it has the advantages of non-contact and non-destructive and the produced color signal is easy to identify,which has great potential applications in the field of food freshness detection.