| Polyaniline（PANI）is currently the most widely used conductive polymer.It has the advantages of low cost,environmental friendliness,and good redox reversibility.However,because pure polyaniline has poor conjugation ability and serious self-aggregation,it greatly affects its electrochemical performance;electrochemical sensors are a hot topic in current research because it is an accurate measurement result The measurement device with low cost,convenient portability and simple principle and preparation has been widely used in many fields such as toxic substance detection,high-quality water source monitoring,biology and medicine,etc.,so it has attracted more and more attention.In this paper,polyaniline and polyaniline/graphene composite materials are mainly used as carriers to construct electrochemical sensors for organic matter detection,and the performance of the two electrochemical sensors is tested.First,cyclic voltammetry was used to prepare PANI.A suitable carrier and inorganic acid were used to prepare PANI.By comparing the parameter changes during the synthesis of polyaniline,it was determined that graphite rods were used as the matrix and perchloric acid was used as the doping acid.The polyaniline electrode prepared under the above synthesis conditions is used to detect and detect different organic substances.The CV method is used to study the electrochemical behavior of organic substances on the polyaniline and polyaniline/graphene modified electrodes.The selected organic acids include organic monobasic acids and dibasic acids.Yuan acid,citric acid,malic acid,sulfosalicylic acid,p-toluenesulfonic acid,ascorbic acid,lactic acid,formaldehyde,the experimental conclusions show that glacial acetic acid,citric acid,ascorbic acid and formaldehyde have a significant effect on the electrical properties of polyaniline electrodes.Choose a formaldehyde solution with a good response to the polyaniline electrode for minimum concentration detection.The test results show that the formaldehyde concentration in the range of 0.0005 to0.0025 mol/L is linear with the peak current intensity of the PANI electrode cyclic voltammetry Relationship,that is,within the formaldehyde concentration range of 0.0005 to 0.0025 mol/L,control p H=1,and use the PANI electrode as a formaldehyde sensor to quantitatively analyze the formaldehyde concentration.The peak current and formaldehyde concentration are linear.The linear equation is Ia=4.68739+804.104 C,the correlation coefficient r=0.997211,the sum of squared residuals is 0.01817,and the detection limit is 0.5 mmol/L.It can be seen that within a certain concentration range,the response peak current has a good linear relationship with the concentration of formaldehyde solution,the detection limit of formaldehyde is 0.5 mmol/L,and shows good stability and reproducibility.The best preparation process for the preparation of polyaniline/graphene composite materials by in-situ polymerization of aniline in an aniline solution containing graphene and the addition of graphene electrodeposition polyaniline/graphene oxide composite film is under the perchloric acid system,the content of graphene When it is 0.2%,it is prepared by the preparation method while stirring.The prepared polyaniline/graphene composite electrode detects the formaldehyde solution.The optimal conditions for the detection are the solution p H=1,the sweep rate is 10 m V/s,and the thickness of the film is the thickness of5 cycles of polymerization.In the range of 0.1～20μmol/L,the peak current density and formaldehyde concentration have a linear relationship,and show good stability and reproducibility.The detection limit of formaldehyde concentration has reached the order of 10-9,the linear equation is Ia=11.06575+0.50242 C,the correlation coefficient r=0.98882,and the sum of squared residuals is 0.26068,which basically achieves trace detection. |
