Study On The Synthesis Of Zinc Oxide-based Microtubules Based On Absorbent Cotton Template And Their Gas-sensitivity Properties

Research on ZnO-based ppb-level H₂S sensors have made great progress in recent years.However,some drawbacks of reported ZnO-based sensing materials,involving high working temperature,slow response/recovery,high detection limit etc.,prevent their practical application in detecting ppb-level H₂S.Meanwhile,the reported fine synthesis methods of hierarchically porous ZnO-based hollow structure are difficult and complicated in practical production with low production rate.Therefore,in this thesis,hierarchically porous ZnO microtubule,NiO/ZnO and CuO/ZnO heterostructural tubules were prepared by metal salts impregnation and subsequently calcination using absorbent cotton as template.The IR,TG,XRD,EDS,SEM,TEM,XPS and BET techniques were utilized to characterize the composition and microstructure of the ZnO-based microtubules.The gas-sensing mechanism was also investigated in detail.Th results of gas sensing performances show that all the hierarchical ZnO-based sensitive materials herein have realized the detection of ppb-level H₂S.In particular,the detection limit of 0.9 at%NiO/ZnO heterostructural microtubule is 1 ppb at 133°C,which represents the lowest detection limit among reported ZnO-based H₂S sensors to date.The 3.67 at%CuO/ZnO-600 sensor shows fast response towards ppb-level H₂S,which represents the fastest response/recovery properties in reported ZnO-based ppb-level H₂S sensors up to now.Therefore,the as-synthesized 3.67 at%CuO/ZnO-600heterostructural tubule can be used as a practical candidate for ppb-level H₂S detection,and the facile synthetic strategy can be applied to prepare other porous SMO heterostructural sensing materials.