Research On Preparation And Gas Sensing Performance Of Porous ZnO Material Based On ZIF-8 As Template

In recent years,owing to the fact that toxic gases can cause damage to environment and human health,people pay great attention to detecting toxic gases.Formaldehyde is one of the toxic gases,which is the main pollutant after home decoration.Formaldehyde also is one of the source materials and it can cause sick building syndrome(SBS).It can bring about many symptoms and pose a threat to people.Hence,many materials are introduced to detect formaldehyde by scientists,such as Au@Sn O2,In2O3-sensitized Zn O nanoflowers,Zn O nanorods,etc.However,those materials have long response/recovery time,which brings inconvenience in detection of formaldehyde.As a result,novel materials with fast response/recovery time and good selectivity to formaldehyde are placed great importance by increasing number of scientists.Metal organic framework(MOF)materials are a new class of crystalline hybrid materials,composed by ordered networks with large specific surface area,high porosity and tunable pore size.This type of materials have some specific properties,contributing to an incredible range of important applications,including gas absorption/separation,drug delivery as well as optical `sensing,etc.Zeolite imidazolate frameworks(ZIFs)are one of the most intriguing MOF materials owing to their practicable synthesis methods and excellent chemical and thermal stability.ZIF-8,Zn-based MOFs,has been applied to many fields owing to its unique structure and great stability.However,it is rarely used in gas sensing directly as a result of its poor gas sensing property.Nevertheless,it is likely to use ZIF-8 as template to prepare metal oxide hollow micro-/nanostructures,which makes it possible to apply this material as template to gas sensing.In this paper,the ZIF-8 is prepared and the optimum synthesis and calcining conditions are explored to improve the gas sensing performance.The details of the study are as follows:(1)ZIF-8 was prepared through static method in this experiment.To explore the effect of solvent on the morphology of ZIF-8,the reaction solvent was changed by DMF,ethanol and methanol.(2)The prepared materials were calcined at 300 °C?350 °Cand 400 °C,and the effects of temperature on the morphology and the composition of the final product were investigated.At the same time,the heating rate was changed,and its influence on the morphology was explored.Next,we explore the gas sensing performance of gas sensor based on Zn O.For the response,the response of the material successfully prepared by using methanol as reaction solvent with the calcination temperature at 350 °C and heating rate at 1 °Cwas highest,which is 10 to 100 ppm formaldehyde;For the selectivity,the material prepared by using methanol as reaction solvent with the calcination temperature at 350 °C and heating rate at 1 °C had good selectivity towards formaldehyde.