Application Of Silicon-based Porous Materials (the Meso-structured Cellular Foam And Sol-gel) In Sensors

The meso-structured cellular foam（MCF）has large pore size and mesoporous pore structure which can ensure the substance and active centers contact to each other,and the substance could transport fastly.The property of MCF will improve the sensitivity of analysis.Organic functional groups immobilized on MCF could enhance the selectivity of the electrode in the recognition system.In this paper,MCF and ionic liquid functionalized meso-structured cellular foam（MCF-IL）were used for construction of modified glass carbon electrodes which can be applied with ion detection and oxygen sensors.In addition,in this work,by using the hydrolysis polycondensation reaction of silica and the property decompose discoloration of Fe（CN）₆^3-ion under low pH and illumination conditions,a illumination label with time memory function was prepared.1.MCFThe MCF was used for construction of modified glass carbon electrode because of its large pore size,large specific surface area and high adsorption performance and the resulting electrode was labeled as MCF/Chit/GC.Here,chitosan effected as the binder.Differential pluse voltanmmetry（DPV）technique was applied to study the eletrochemical response of Sn（Ⅱ）on the MCF/Chit/GC electrode.The experimental results showed that MCF/Chit/GC electrode has a good linear response of Sn（Ⅱ）in range of 6.25μmol/L⁴3.75μmol/L.The MCF-IL was used for construction of modified glass carbon electrodes.Here,chitosan was used as the binder and the resulting electrode was labeled as MCF-IL/Chit/GC.By adsorption effect,MCF-IL/Chit/Fe（CN）₆^3-/GC was prepared by dipping MCF-IL/Chit/GC electrode in Fe（CN）₆^3-solution.Due to Fe（CN）₆^3-is an effective anionic electron mediator with excellent electron transferability and a high degree of reversibility,the Fe（CN）₆^3--confined electrode performed well redox electrochemical behaviour.Through adding oxygen to the system,it was found that these Fe（CN）₆^3--confined electrodes have a directly electrochemical response to the dissolved oxygen,that the redox peak currents of Fe（CN）₆^3-/4-on MCF-IL/Chit/Fe（CN）₆^3-/GC surface were shrunk.By comparison the response of oxygen at MCF/Chit/Fe（CN）₆^3-/GC and MCF-IL/Chit/Fe（CN）₆^3-/GC electrodes,it was found that the MCF-IL/Chit/Fe（CN）₆^3-/GC had a better linear response for oxygen concentration in range of 6.5⁷.8 mg/L（r=0.9972）.The reasons of MCF-IL/Chit/Fe（CN）₆^3-/GC behaving better responses to oxygen concentration were summarized as follows:The first one is that chitosan has good chelating ability.The second one is that the imidazolium-based ionic liquid group could adsorb more Fe（CN）₆^3-because imidazolium has strong interaction with Fe（CN）₆^3-.The last one is that the meso-structured cellular foam has a three-dimensional porous structure which could beneficial to the transmission of the substrate.2.Sol-gelThe traditional sol-gel preparation method has the disadvantage of being easy to crack.In order to avoid the cracking phenomenon of sol-gel,the ionic liquid（1-butyl-3-methylimidazolium tetrafluoroborate）is introduced,and then crack-free sol-gel can be obtained in this system.On this basis,by using the property decompose discoloration of Fe（CN）₆^3-ion under low pH and illumination conditions,a graded color crack-free sol-gel was prepared.Through optimized the concentration of Fe（CN）₆^3-ion in the system,a illumination label with time memory function was prepared.