The Electrochemical Performance And Analytical Application Of Metal Oxides Derived From Iron-group Elements Organic Gels

As an emerging“smart”soft material,metal-organic gel（MOG）are attracting more and more researcher’s attentions,and MOG have been broadly applied in chemical sensing,adsorption,drug delivery,crystal growth,recognition and separation of chiral compounds,electrolyte materials and so on.Combined with the composition characteristics of MOG materials and the advantage of simple synthesis,the research based on MOG derived materials has became a new mode to expand the application of MOG material.However,the research based on MOG derived materials is still in the preliminary stage,the types and amounts of derived materials are relatively small,particularly for the MOG derived metal oxide materials.The MOG derived oxides would have different physicochemical properties through facilely adjusting the compoisitions of MOG precursors.Therfore,this work selected the organic ligand 4,4’,4’’-[（1,3,5-triazine-2,4,6-triyl）tris（azanediyl）]tribenzoic acid（H₃TATAB）to construct composition adjustable MOG systems with the iron-group elements metal ion of Co²⁺,Fe³⁺,and Ni²⁺.Then,a series of metal oxides were obtained through directly calcining towards as-prepared MOG materials.Last,the electrocatalytic performance and analytical application in gas sensing and electrochemical detection of the derived metal oxides was surveyed,respectively.The detailed contents are as follows:1.The preparation of iron-group elements organic gels and the derived metal oxides.The monometallic,bimetallic,and trimetallic organic gels were prepared through facilely mixing the iron-group elements metal ion of Co²⁺,Fe³⁺,and Ni²⁺solution and ligand solution at room temperature.Then,the as-prepared MOG were suffered freeze-drying treatment to obtain the corresponded metal-organic xerogel（MOX）.Last,the metal oxides were synthesized through the further calcination treatment towards the MOX.The MOG and MOG derived metal oxides were characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）,selected area electron diffraction（SAED）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,and Raman spectrum.2.The electrocatalytic performance of metal oxides derived from iron-group elements organic gels.The physicochemical properties of spinel metal oxides are highly dependent on the compositions,structural parameters,and distributions and oxidation states of the cations.In order to verify the relationship between the catalytic properity and the composition of metal oxides,the electrocatalytic water oxidation reaction was selected as research model to survey the electrocatalytic performance of these metal oxides derived from the iron-group elements organic gels.The overpotential and Tafel slope were employed to evaluate the electrocatalytic performance of derived metal oxides,and the results suggesting that multi-metal oxides exhibited higher electrocatalytic actives than mono-metal oxides and the electrocatalytic actives of multi-metal oxides were also dependent on their compositions.3.The analytical application of metal oxides derived from iron-group elements organic gels.Based on the semiconductor property and good electric conductivity of metal oxide,the Fe-MOG derived?-Fe₂O₃ was employed to sensing acetone gas and the Co-MOG derived Co/CoO/Co₃O₄ was employed as electrode modified material to electrochemically detect diethylstilbestrol（DES）.In the research of gas sensing,the prepared gas sensor shown a wide response range from 5 to 900 ppm for acetone gas,a high response value of 27 and fast response/recovery time of 1 s/80 s for 100 ppm acetone gas.In the research of electrochemical detection,the Co/CoO/Co₃O₄ could significantly accelerate the redox reaction of DES at the modified electrode interface and improve intensity of electrochemical redox currents.Therefore,an analytical method of DES with a wide range from 0.5 to 142.9?M and a low limit detection of 0.022?M have been established through cycle voltammetry（CV）method.In summary,this work conducted facile calcination treatment towards iron-group elements organic gels to prepare metal oxides.The performance of electrocatalytic water oxidation reaction and the analytical application in gas sensing and electrochemical detection of MOG derived metal oxides were investigated,respectively.This work not only enriched the research contents of MOG derived metal oxides,but also provided and proved an effective strategy to prepare metal oxide materials with excellent performance.