Preparation And Electro-Catalytic Performance Of Polyoxometalates-Based Graphene Nanocomposites

The water pollution in our country has become more and more serious with the development of industry.Electrochemistry has a significant effect on the treatment of wastewater.Electrochemical treatment is a kind of “environmental friendly technology”,which can effectively deal with the refractory organics.Now how to improve the efficiency of electro catalytic technology in the electrochemical field has been the goal of the scientific field.Polyoxometalates?POMs?have the characteristics of acid catalytic and oxidation reduction,and they are widely used in environment,catalysis,material science and surface science.However,its application is limited because of its small specific surface area and difficult to be separated.Graphene has a high specific surface area,excellent thermal conductivity and excellent electron transfer capability and so on.In order to solve the drawbacks of polyoxometalate,three kinds of polyoxometalates/graphene nanocomposites based on polyoxometalates and graphene were synthesized,which greatly improved the catalytic activity and expanded the application space.The characterization of PMo₁₂-rGO,FePMo₁₂-SiO₂-rGO and PMo₁₂-PAN-rGO were characterized by X ray diffraction?XRD?,infrared spectrum?FTIR?,scanning electron microscope?SEM?and specific surface area test?BET?,which proved POMs still retained Keggin structure and the composites can be used in wastewater treatment and detection of trace substances.Cyclic voltammetry showed that the composite modified electrodes PMo₁₂-rGO/GCE,FePMo₁₂-SiO₂-rGO/GCE and PMo₁₂-PAN-rGO/GCE had better response in 0.5 mol·L-1 H₂SO₄.The surface coverage of the active substances for the three electrodes were 6.4×10-9 mol·cm-2 ? 6.3×10-9 mol·cm-2 and 2.5×10-8 mol·cm-2,respectively.Scanning speed experiment showed that the peak current of the electrodes increased with the increase of scanning speed,and the electrode processes of the three composite modified electrodes were analyzed.The impedance of three modified electrodes was much smaller than the bare electrode,which reflected the conductive of three modified electrodes modified by phosphomolybdic compound was increased and accelerated electron transfer effect on the electrode surface.The test for the concentration of nitrite of composite material modified electrode showed that the response current increased with the increase of the concentration of nitrite.It was showed that the modifiedelectrodes had high sensitivity when the nitrite ion concentration was in the range of40²000 ?M·L-1.the detection limits of the three electrodes were 0.078,0.07 and0.24?M·L-1,respectively.In summary,the study found that polyoxometalate-graphene three electrode system has good Electrocatalytic response of nitrite wastewater.The catalytic material of polyoxometalates synthesized by biotemplate method and modified with polyaniline have high catalytic performance.The modified electrodes have good electrocatalytic properties.This study extends the application of polyoxometalates in electrochemical field in basic theory research and technology research.