| Transition metal materials are promising nanomaterials,which have attracted much attention due to their low price,controllable morphology and high catalytic activity.In the past few decades,people have carried out extensive research on nonprecious transition metal materials.Based on the excellent characteristics and properties of transition metal materials,they are widely used in the fields of electronics,catalysis,energy and sensing.There are many kinds of transition metal materials,including transition metal oxides,transition metal dihalides,transition metal hydroxides and metal organic frameworks(MOFs).In this paper,the applications of transition metal dihalides and MOFs in electrochemical sensors are studied.Graphene(Gr)is a kind of nano-layered carbon material with excellent electrical conductivity,which is often used as the supporting material in electrochemical analysis.However,Gr is easy to agglomerate and stack,resulting in poor dispersion,which affects the performance of Gr,so it is often functionalized to overcome this deficiency.In electrochemical sensors,materials are usually modified on the electrode surface to enhance its analytical performance.Compared with a single nanomaterial,the interaction and synergistic effect of the components in the nanocomposite make its performance more excellent.The comprehensive performance of the electrochemical sensor can be significantly enhanced by using the nanocomposite modified electrode.Therefore,in this paper,PSS functionalized graphene(PSS-Gr)was used as the supporting material,and combined with transition metal materials possessing different properties to obtain new nanocomposites.The electrochemical sensors based on novel nanocomposites were constructed for the detection of phenolic pollutants.In addition,a molecularly imprinted membrane with specific recognition for allura red was formed by electropolymerization on the surface of the obtained composite for the purpose of improving the selectivity of the sensor,which realized the sensitive and selective detection of allure red.The main contents of this paper are as follows:(1)Construction of novel electrochemical sensor based on a composite of MoS2 quantum dots decorated PSS functionalized grapheneIn this experiment,MoS2 QDs were first synthesized and then added the precursor solution of MoS2 QDs in the process of reducing graphene oxide to obtain MoS2 QDs QDS@PSS-Gr The composite was characterized by transmission electron microscopy,X-ray photoelectron spectroscopy and electrochemical techniques.The electrochemical signal of BPA was significantly enhanced when the composite was modified on the electrode surface,which indicated that the nanocomposite possessed obvious electrocatalytic effect on the oxidation of BPA.Therefore,a new analytical method for the determination of BPA was established.Under the optimal conditions,the oxidation peak current of BPA was proportional to its concentration,and the linear range was 0.06?1.0 ?M and 1.0?8.0 ?M.The detection limit was 0.008 ?M.The electrochemical sensor constructed in this experiment was highly sensitive,and the method could be used for the analysis of BPA in real sample with satisfactory recovery.(2)Fabrication of simultaneous and sensitive dihydroxybenzene isomers electrochemical sensor based on composite of Cu-TCPP nanosheets and PSS functionalized grapheneDihydroxybenzene isomers have attracted much attention due to their nondegradability and high toxicity,which are harmful to the environment and human.However,it is challenging to detect and distinguish simultaneously dihydroxybenzene isomers due to the fact that they coexist in samples.In this experiment,we synthesized PSS-Gr@Cu-TCPP nanocomposite by mixing Cu TCPP nanosheets with PSS-Gr by a simple ultrasonic method,which was also characterized by a variety of techniques.The electrochemical behaviors of dihydroxybenzene isomers including hydroquinone(HQ),catechol(CT)and resorcinol(RS)on PSS-Gr@Cu-TCPP/GCE were investigated and their oxidation peak potentials were separated evidently with the oxidation peak currents enhanced significantly,which were attributed to the remarkable electrocatalytic activity of the nanocomposite on three isomers.A novel electrochemical sensor based on this material was constructed to simultaneously determine dihydroxybenzene isomers.The linear ranges of the sensor for HQ,CT and RS were 1?200 ?M,0.08?120 ?M and 5?100 ?M and the detection limits were 1 ?M,0.08 ?M and 5 ?M,respectively.The sensor showed high sensitivity and wide linear range.Finally,it was successfully applied to determine three dihydroxybenzene isomers in practical samples with satisfactory recoveries.(3)A sensitive molecularly imprinting imprinting electrochemical sensor based on a hybrid of MIL-53(Fe)nanorod and PSS functionalized grapheneMolecular imprinting technique is an important method to improve the selectivity.The combination of molecular imprinting and nanomaterials can effectively improve the selectivity of analytical methods and achieve the selective detection of analytes.In this experiment,we synthesized rod-like MIL-53(Fe)and compounded them with PSSGr for the preparation of PSS-Gr@MIL-53(Fe)nanocomposite.The composite was characterized by a variety of techniques.Based on this material,a molecularly imprinted polymer(MIP/PSS-Gr@MIL-53(Fe))with allura red recognition sites was formed on the surface of the material by electropolymerization using ophenylenediamine as monomer.An indirect method for the determination of allura red was established by differential pulse voltammetry(DPV)with[Fe(CN)6]3-/4-as probe.Under the optimal conditions,the peak current of the probe was proportional to the concentration of allure red.The linear range was 0.04?0.1 ?M and 0.1-2.0 ?M and the detection limit was 2.0 ×10-8 M.Finally,the sensor was successfully applied for the determination of allure red in real drink sample.In this paper,three novel electrode materials were explored,and three novel electrochemical sensors were successfully constructed through the synergistic effect of transition metal dihalides and MOFs with functional graphene.The excellent properties of transition metal dihalides and MOFs materials have been proved,and their application in electrochemical analysis has been expanded. |
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