CN107966485A - A kind of electrochemical heavy metals detector and its detection method based on graphene test paper electrode structure - Google Patents
A kind of electrochemical heavy metals detector and its detection method based on graphene test paper electrode structure Download PDFInfo
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- CN107966485A CN107966485A CN201711287714.5A CN201711287714A CN107966485A CN 107966485 A CN107966485 A CN 107966485A CN 201711287714 A CN201711287714 A CN 201711287714A CN 107966485 A CN107966485 A CN 107966485A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/308—Electrodes, e.g. test electrodes; Half-cells at least partially made of carbon
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/09—Use of materials for the conductive, e.g. metallic pattern
- H05K1/092—Dispersed materials, e.g. conductive pastes or inks
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
- H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
- H05K3/1216—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by screen printing or stencil printing
Abstract
The invention discloses a kind of electrochemical heavy metals detector and its detection method based on graphene test paper electrode structure, electrochemical heavy metals detector includes the graphene printing paper electrode that electrochemical detection system and its input terminal connect, and graphene test paper electrode includes PET base and the working electrode printed thereon by typography, to electrode, reference electrode, silver conductive baseline and insulating layer；Working electrode is printing graphene, is printing carbon to electrode, and reference electrode is printing silver/silver chlorate, and working electrode surface deposition has one layer of bismuth film；The content of heavy metal ion, 10 retest rate of recovery are less than 5% for 92.5%, RSD in the electrochemical heavy metals detector test lake water sample that the present invention uses, the testing time<15 minutes；Test limit<1µmol/L；Relative deviation is compared with atomic absorption method<5%, therefore the electrochemical heavy metals detector in the present invention has higher accuracy and practicality.
Description
Technical field
The present invention relates to detecting instrument technical field, more particularly to a kind of electrochemistry based on graphene test paper electrode structure
Heavy metal detector and its detection method.
Background technology
Due to traditional method in environmental testing in application, equipment, cost, measurement period, sensitivity etc. are first
Nature deficiency, therefore traditional method is extremely limited in the field.Therefore, people will find various methods and go
Substitute and develop traditional chemistry, physics measurement means, electrochemical sensor due to its high sensitivity, short cycle of measurement,
The traditional advantage of high reliability etc. and the great concern for obtaining people, for decades, become in environmental testing
Interior research hotspot simultaneously has been widely used.Currently used detection of heavy metal ion method has atomic emission spectrometry
（AES）, atomic absorption spectrography (AAS)（AAS）, inductive coupling plasma-Mass Spectrometry（ICP-MS）Deng.But these methods
Due to complicated, expensive equipment, the reasons such as inconvenience are carried, are difficult to realize field monitoring.Electroanalytical Chemistry is as analysis hand
Section, the phenomenon of chemical change and electricity is combined closely, the basic principle of Applied Electrochemistry and experimental technique research material
Composition, it is various to analyze the component content method of test substances, is widely used, technically makes rapid progress, constantly deep in theory
Enter, improve and advance.In scientific research and practical application, electrochemical method is not only an analysis method, and is also one
The essential tool of kind research, uses electrochemical sensor instrument simple, is a kind of generally acknowledged easy to be automated with computer interconnection
It is quick, sensitive, accurately micro and trace analysis methods, as long as usually a few minutes can survey a sample, data are automatic
Preserve, can under complex environment live on-line checking, the concentration for measuring metal ion can be with as low as 10-12 mol/L.It is existing
Heavy metal Electrochemical Detection instrument connects three electrodes typically by electrochemical workstation, and column electrode, nothing is usually used in electrode
By be detection sensitivity and portability on equal existing defects, therefore develop it is a set of based on the new of electro-chemical test principle
Type heavy metal analysis instrument, realizes that contents of many kinds of heavy metal ion includes lead in Complex water body（Pd2+）, cadmium（Cd2+）, copper（Cu2+）It hurry up
Fast, sensitive, accurate scene on-line checking, it is imperative.
The content of the invention
It is an object of the invention to provide a kind of graphene test paper electrode and its heavy metal detector based on electrochemistry of foundation,
It can be realized includes lead to contents of many kinds of heavy metal ion（Pd2+）, cadmium（Cd2+）, copper（Cu2+）Quickly, sensitive, accurate detection,
And more convenient operation and carrying.
One of present invention is to provide a kind of electrochemical heavy metals detector based on graphene test paper electrode structure, including electricity
Chemical detection system and the three-electrode electrochemical sensor of its input terminal connection, the three-electrode electrochemical sensor is graphite
Alkene prints paper electrode；The work that the graphene printing paper electrode includes PET base and printed thereon by typography
Electrode, to electrode, reference electrode, silver conductive baseline and insulating layer；The working electrode is printing graphene, described to electricity
Carbon is extremely printed, the reference electrode is printing silver/silver chlorate；The working electrode is located at PET base center, described to electricity
Pole, reference electrode are respectively separated to be not in contact with each other positioned at the periphery of working electrode and three, the working electrode, to electrode and ginseng
Distinguish external silver conductive baseline than electrode；The insulating layer is enclosed in the periphery to electrode, reference electrode and makes its internal shape
Into working region；The insulating layer at the same time covers the silver conductive baseline, and the silver conductive baseline stretches out
Go out insulating layer and form contact jaw；The working electrode surface deposition has one layer of bismuth film.
It is further preferred that the working electrode is circle, it is described respectively arc-shaped to electrode, reference electrode.
Further, the electrochemical detection system is for electrochemical workstation or including with lower structure：
Power supply circuit, for each circuit power supply in system；
Control circuit, for the operation of each circuit in control system, receives electrochemical signals and handles；
I/V conversion circuits, the current signal for three-electrode electrochemical sensor to be produced are converted into voltage signal；
Filter circuit, for removing the interference signal in transformed voltage signal；
Amplifying circuit, for being amplified to voltage signal；
A/D convertor circuit, for voltage signal to be converted into digital signal by analog signal；
Bipolarity generation circuit, for producing the circuit of positive and negative bipolar voltage,
Potentiostatic circuit, the potential for keeping three-electrode electrochemical sensor working electrode are maintained at steady state value；
Serial ports output circuit, for exporting printing function by serial ports, will collect data and is depicted as curve by processing；
Display circuit, for being shown the signal collected by liquid crystal display；
The bipolarity generation circuit, A/D convertor circuit, serial ports output circuit and display circuit respectively with the control circuit
Connection, the potentiostatic circuit are connected with bipolarity generation circuit, and the I/V conversion circuits, filter circuit, amplifying circuit are successively
It is connected with A/D convertor circuit；The potentiostatic circuit, I/V conversion circuits are connected with three-electrode electrochemical sensor；The control
Circuit processed, I/V conversion circuits, filter circuit, amplifying circuit, A/D convertor circuit, bipolarity generation circuit, potentiostatic circuit, string
Mouth output circuit and display circuit are connected with power supply circuit.
It is further preferred that the bipolarity generation circuit can be programmed to produce the voltage letter of different wave
Number.
It is further preferred that the control circuit selection STM32 microcontrollers
Further, the preparation method of the graphene printing paper electrode comprises the following steps：
（1）The preparation of three-dimensional porous graphene assembly：It is 80mg/ that graphene oxide, which is distributed in deionized water, and forms concentration
The graphene oxide dispersion of ml, then adds dopamine and hydrophilic imidazole ion liquid 1- butyl 3- methylimidazole tetrafluoro boron
Hydrochlorate carries out hydro-thermal reaction, and the graphene oxide, dopamine, the mass ratio of 1- butyl 3- methyl imidazolium tetrafluoroborates are
1.5-2.5:1:4-6；When the hydro-thermal reaction is 85-95 DEG C of isothermal reaction 5-7 small；Hydro-thermal reaction obtains having three-dimensional porous knot
The graphene hydrogel of structure, is then freeze-dried up to graphene aerogel；
（2）By step（1）Obtained graphene aerogel, which is distributed in aqueous solution, prepares graphite olefinic functionality slurry, while configuration is led
Electrical carbon is starched and conductive silver paste, and the graphene test paper electrode of the three-electrode system of assembling, wherein graphite are then prepared by print process
Alkene paper electrode is working electrode, and it is reference electrode to electrode, printing silver/silver chlorate that printing carbon, which is,.
It is further preferable, the step（1）Middle graphene oxide dispersion concentration is 80mg/ml.
It is further preferable, the step（1）Middle graphene oxide, dopamine, 1- butyl 3- methylimidazole tetrafluoro boron
The mass ratio of hydrochlorate is 2:1:5.
It is further preferable, the step（1）When middle hydro-thermal reaction is that 90 DEG C of isothermal reactions 6 are small.
Further, the step（1）In graphene oxide be prepared by following steps：
Cold stage：First by the concentrated sulfuric acid that 230 milliliters of mass fractions are 98%, 0 DEG C is cooled to；Then in the feelings quickly stirred
The mixture of 10 grams of natural graphite powders and 5 grams of sodium nitrate is added under condition；30 grams of potassium permanganate are then slowly added into, control temperature
When reaction 2 is small in the range of 10 ~ 15 DEG C；
Middle thermophase：By reacting liquid temperature control in the range of 32-38 DEG C, continue in the case of stirring reaction 2 it is small when；
Hot stage：460 ml deionized waters are continuously slowly added into reaction solution, temperature is risen to 98 DEG C, dimension
Hold and react 30 minutes at this temperature；Again 1400 milliliters are diluted to deionized water；
Then the H of 30 milliliters of 5 % of mass fraction is added into reaction solution2O2, it was observed that color becomes glassy yellow, filter while hot
Obtain graphene oxide crude product；
Then the HCl/water solution that graphene oxide crude product mass fraction is 5% is rinsed, then be washed with deionized repeatedly extremely
There is no SO4 in filtrate2-Ion；Adding 3200 ml deionized waters into graphene oxide crude product again, to obtain graphene oxide molten
Liquid；
Then pass through multiple centrifugal concentrating graphene oxide solution；By repeatedly washing, the pH value of graphene oxide solution is washed
To neutrality, finally by obtaining solid oxidation graphene after centrifugation, washing, vacuum drying.
It is further preferred that just generation graphene oxide solution needs to carry out the ultrasonication of three hours in centrifugation；It is described
Ultrasonic temperature is less than 35 DEG C.
It is further preferred that the selection of potassium permanganate feed postition points 3 batches adds in 1 h to system in the cold stage
Enter.
Further, the print process step is：
（1）The electrode shape that paper electrode is printed according to graphene makes halftone；
（2）Halftone is adjusted with substrate to suitable distance, halftone is fixed；
（3）Graphite olefinic functionality slurry and conductive carbon paste, conductive silver paste are placed on halftone, air pressure is adjusted and stone is printed in substrate
Black alkene layer, carbon-coating and silver layer；Dry and recycle slurry,
（4）After the same method insulating layer, drying are printed in insulating layer region；
（5）Print electrode obtained in hydrochloric acid solution Anodic Oxidation, silver layer surface is oxidized to silver chlorate, silver/chlorine is made
Change silver-colored reference electrode.
It is further preferred that the step（1）The mesh of middle halftone is 200 ~ 250；
It is further preferred that the step（3）Middle drying is dried 15 minutes for 110 DEG C；
It is further preferred that the step（3）It is middle to use polyester film as printed substrates；
It is further preferred that the step（3）Middle printing holding electrode surface printing is smooth and electrode resistance difference between batch is less than 5%；
It is further preferred that the step（4）Middle drying is dried 10 minutes for 175 DEG C；
It is further preferred that the step（5）Middle hydrochloric acid solution mass concentration is 7%.
It is to be based on following principle that the working electrode surface deposition, which has one layer of bismuth film,：The toxicity of bismuth metal is extremely low, is considered
It is a kind of environmentally protective metal.Research show that bismuth metal has the electroanalysis performance similar with mercury, can with many heavy metals from
Son forms the binary or multicomponent alloy similar to amalgam.In terms of heavy metal analysis, bismuth pole has overpotential height, background current
Low, electrochemical window mouth width, dissolution peak separator well, the advantages that stability is good, surface easily updates.In addition, bismuth pole is unwise to dissolved oxygen
Sense, therefore can be analyzed under conditions of not deoxygenation, operation complexity is enormously simplify, is had in terms of heavy metal ion super sensitivity detection
Have wide practical use.
Further, the deposition bismuth film comprises the following steps：
（1）Bismuth nitrate is dissolved in hac buffer, Bi in obtained solution3+Concentration is 400-600 micrograms per litres；
（2）The graphene printing paper electrode that print process obtains is placed in above-mentioned solution, is deposited under permanent potential -1.4 ~ -1.0V
200-400s, is stirred continuously in deposition process, and printing graphene surface in the working electrode of graphene test paper electrode forms bismuth
Film.
It is further preferred that the step（1）Solution in Bi3+Concentration is 500 micrograms per litres；The hac buffer
The concentration of middle acetic acid is 0.2 mol/L, pH 4.6；
It is further preferred that the step（2）Control deposits 300s under permanent potential -1.2V in middle deposition.
The two of the present invention are to provide a kind of detection method of the heavy metal detector based on electrochemistry, specific as follows：
（1）The heavy metal analysis graphene test paper electrode of supported active functional material is connected with electrochemical detection system first；
（2）Electrochemical workstation is opened, then drawing prepare liquid with the pipettor of corresponding range is added dropwise graphene test paper electrode
Working electrode surface；
（3）By differential pulse ASV technology for detection heavy metal ion, two stages, first stage heavy metal ion are specifically divided into
Deposition, deposition voltage is the V of -1.0 V ~ -0.7, and sedimentation time is 120-240 s；It is static after deposition, tranquillization electricity
The position V of -1.0 V ~ -0.7, settling time is 40 ~ 90 s.
It is further preferred that the step（1）After line connects, it is corresponding to survey conducting wire both ends respectively using electronic multimeter
Resistance, see that resistance value is no within zone of reasonableness.
It is further preferred that the deposition voltage is -1.0 V, the sedimentation time is 120s；The resting potential -1.0
V, the settling time are 60 s.
It is further preferred that the step（3）The starting voltage of differential pulse ASV is -0.8 V, and final voltage is -0.1
V, 50 mV of impulse amplitude, 50 ms of pulse width.
It is further preferred that after detection, the graphene test paper 30 s of stirring and washing under the constant potential of 0.1 V reaches again
It is raw.
The heavy metal ion includes conventional contents of many kinds of heavy metal ion, especially Cd2+, Pb2+ and Cu2+.
The present invention using graphene printing paper electrode and supporting electrochemical analysis system test lake water sample in heavy metal from
The content of son, 10 retest rate of recovery are less than 5% for 92.5%, RSD, the testing time<15 minutes；Test limit<1 µmol/
L；Relative deviation is compared with atomic absorption method<5%, and operability and portability are more convenient, therefore the graphite in the present invention
Alkene paper electrode and electrochemical heavy metals detector have higher accuracy and practicality.
Brief description of the drawings
Fig. 1 is the structure diagram of graphene printing paper electrode；
Fig. 2 is the circuit diagram of electrochemical detection system；
Fig. 3 is the scanning electron microscope diagram for printing graphene paper；
Fig. 4 is the standard heavy ion Stripping Voltammetry curve map of various concentrations；
Fig. 5 is concentration-current standard curve map of different heavy metal ion；
In figure：1st, PET base, 2, working electrode, 3, to electrode, 4, reference electrode, 5, silver conductive baseline, 6, insulating layer.
Embodiment
Embodiment 1
A kind of preparation method of graphene oxide, oxygen is prepared using the method for chemical oxidation-ultrasound stripping-electronation
Change type graphene, influence of the research reaction condition for synthesis oxidisability quality of graphene.:We are on the basis of Hummers methods
Some technical improvement of upper combination, prepare graphene oxide.Preparation method reaction can be divided into three phases, be respectively：It is low
Thermophase（Temperature is maintained in the range of 10 ~ 15 DEG C）, middle thermophase（Temperature is maintained in the range of 32 ~ 38 DEG C）With high temperature rank
Section（Temperature is maintained at 98 DEG C）.Comprise the following steps that：
Cold stage：230 milliliters of concentrated sulfuric acids are carefully added into 2 liters of round-bottomed flask first, round-bottomed flask is in ice-water bath
It is cooled to 0 DEG C.Then the mixture of 10 grams of natural graphite powders and 5 grams of sodium nitrate is added in the case of quick stirring.It is then slow
30 grams of potassium permanganate are slowly added, control temperature at this time in the range of 10 ~ 15 DEG C, when reaction 2 is small at this temperature.
Middle thermophase：Ice-water bath is removed at this time, dries round-bottomed flask, is transferred in oil bath, and the temperature control in this stage is in 32-
In the range of 38 DEG C, continue in the case of stirring reaction 2 it is small when.
Hot stage：It is continuous at this time but very slowly add 460 ml deionized waters, temperature is risen to 98 DEG C, dimension
Hold and react 30 minutes at this temperature, it is observed that the color in this stage is brown.Again 1400 millis are diluted to deionized water
Rise, the color gradient in round-bottomed flask is into brown at this time.
The H2O2 of 30 milliliter of 5 % is eventually adding, it was observed that color becomes glassy yellow, is filtered while hot.
Then rinsed with 5% HCl/water solution, then washed three times with 1400 ml deionized waters altogether again, make not having in filtrate
There is SO4 2-Ion（Precipitation is not produced with BaCl2 aqueous assays）, 3200 ml deionized waters are added, at this time graphene oxide
Mass fraction close to 0.5%.
Then by repeatedly being centrifuged under the rotating speed of 14000 rpm, graphene oxide solution is concentrated.By repeatedly washing,
The pH value of graphene oxide solution is washed till neutrality, finally by centrifugation, washing, obtains solid oxidation graphite after vacuum drying
Alkene.
Oxidized form graphene can obtain graphene product by adding reducing agent electronation.
Experimental condition optimization
（1）Influence of the oxidant feed postition to product morphology under low-temp reaction
In experimentation, potassium permanganate during our system researches low-temp reaction（KMnO4）Feed postition to graphite
Intercalation play an important role, and then the structure and pattern of product are had an impact.When continuous to system (in 15 min)
KMnO4When, obtained product is multilayer GO, and thickness is about 10 nm；Added when (dividing 3 batches in 1 h) in batches to system
KMnO4When, obtained product is individual layer or two layers of GO, and thickness is about 1.7 nm.This is because in low-temp reaction（5~10 ℃）
During, KMnO4Effect be graphite oxide aspect edge, while hydrogen sulfate ion and sulfuric acid molecule pass through electrostatic interaction
Absorption is at the edge of graphite aspect.With in the progress of reaction and system, potassium permanganate amount is continuously increased（10~20 ℃）, stone
The honeycomb crystal lattice plane of ink gradually becomes the plane macromolecular of positively charged, and hydrogen sulfate ion and sulfuric acid molecule are inserted into graphite
Between layer gap, sulfuric acid-compound between graphite layers are formed.Under low temperature, the speed entirely reacted is relatively slow, it is necessary to which time enough allows
Intercalation fully carries out.Therefore, by a long time in batches to the method more GO of system addition potassium permanganate）Synthesis
Beneficial to the intercalation of graphite, monodispersed GO is finally obtained.
（2）Influence of the reaction temperature to product morphology under pyroreaction
After medium temperature is reacted, deep oxidation occurs for sulfuric acid-compound between graphite layers.With the addition of dampening, system is reacted into
Hot stage, the concentrated sulfuric acid makes mixeding liquid temperature raise rapidly with water effect in mixed system, sulfuric acid-graphite layers of deep oxidation
Compound hydrolyzes, and a large number of water molecules enters intercalation compound, and the increase of graphite flake layer spacing, produces obvious volumetric expansion.
Therefore, the structure and pattern of product can be influenced by controlling the temperature of reaction system.When system temperature is more than 100
DEG C, it is multilayer GO to obtain product, and thickness is about 4.5 nm；When system temperature is at 70-100 DEG C, product thickness, which is made, is about
1.2 nm, are exactly the characteristic feature of individual layer GO.This is because there are the hydrolysis of compound between graphite layers at the same time in pyroreaction
React and by pyrolysis.When the temperature of mixed liquor is appropriate, hydrolysis is occupied an leading position, and mixeding liquid temperature is excessive
When, graphite oxide interlayer compound is discharged CO and CO2 by thermal decomposition, so that cause oxy radical to reduce, aluminum oxide/graphite layer
Between the graphite oxide that completely peeled off can not be accumulated again between layers in follow-up ultrasonication of hydrone.Therefore, it is real
The temperature for testing control pyroreaction carries out 24 h vacuum drying between 70-100 DEG C.
（3）Influence of the ultrasonic procedure to graphene nano size
Graphene is as a kind of two-dimensional material, and height is about 1 nm, and lateral dimension distribution is from several microns to hundreds of
Nanometer.First, oxidizing process itself can cause graphite to be destroyed for less fragment.Secondly, the ultrasonic stripping process in water phase
Also GO structural damages are caused.Therefore, it is broken that the ultrasound (200 W, 90%) of three hours is carried out to just generation GO aqueous solutions, then
By centrifuge (14000 rmp, 20 min) separation prepare two-dimensional be distributed in tens to hundreds of nanometer ranges GO it is broken
Piece.Compared with the average-size of original several microns of orders of magnitude, the GO sizes after ultrasonication are reduced to hundreds of nanometers.This
Outside, in ultrasonic procedure, the temperature of control system to be not higher than 35 DEG C, excessive temperature can cause between GO layers of reduced size
Reunite.
（4）The selection of sulfuric acid dosage
The ratio of sulfuric acid and graphite powder is the corresponding 23mL concentrated sulfuric acids of 1g graphite powders, and the excessive concentrated sulfuric acid makees solvent, can make NaNO3
Concentrated nitric acid is converted into, strengthens oxidation.In addition, potassium permanganate generates permanganic acid in concentrated sulfuric acid, the chemical valence of manganese is+7, oxygen
The property changed is most strong.During the reaction, since the oxidation of graphite, system can be extremely very sticky, excessive sulfuric acid can play dilution
Effect, reduces system viscosity, is conducive to uniform stirring, ensures that also oxidant comes into full contact with graphite.
Embodiment 2
A kind of preparation method of graphene printing paper electrode, its principle is with the persursor material of graphene --- oxidized form graphene
（graphene oxide, GO）Nanometer sheet is raw material, develops the scale packaging technology of graphene macroscopic material, by GO certainly
The distinctive surface functional group of body and chemical property, chemical reducing agent dopamine exist and hydrothermal condition under, reduction GO lamellas with
Lamella takes mutually product and connection restructuring, and the porous graphene assembly of macroscopic three dimensional is constructed using GO nanometer sheets as construction unit.
Three-dimensional porous graphene assembly not only inherits the excellent performance of two-dimensional graphene nano material such as high conductivity, chemistry/heat
Stability and mechanical strength etc., also have been assigned the micro-nano porous structure of uniqueness and big ratio surface by its three-dimensional assembling process
Product；By probing into a series of important features of three-dimensional grapheme assembly and physicochemical properties, synthesis technologic parameter is disclosed
The affecting laws formed with assembling condition to graphene assembly, deepen dynamic (dynamical) to grapheme material self assembling process to recognize
Know；During electronation and hydro-thermal assemble, hydrophilic glyoxaline ion liquid is added（ionic liquid, IL）With
Graphene assembles altogether, using the cation-π interaction between the glyoxaline cation of IL and graphene nanometer sheet π surfaces by IL
Molecule is grafted to graphene assembly surface, improve three-dimensional porous grapheme material can solution operability, realize to graphene
Assembly is microcosmic and the accuracy controlling of macrostructure and chemical property；Good using the graphene assembly of IL molecules grafting
Solvent-dispersible and film forming, graphene paper electrode is prepared by print process.
Specific preparation process is as follows：
1st, the preparation of three-dimensional porous graphene assembly
GO constructs three-dimensional porous graphene-based gel rubber material as elementary cell is constructed using hydro-thermal method.By the GO of ultrasonic disperse
(80 mg mL-1) and reducing agent dopamine and hydrophilic imidazole ion liquid 1- butyl 3- methyl imidazolium tetrafluoroborates（1-
Butyl-3-methylimidazolium tetrafluoroborate, BMIMBF4）It is put into 90 DEG C of constant temperature in hydrothermal reaction kettle
React 6 it is small when, the mass ratio of GO, dopamine and 1- butyl 3- methyl imidazolium tetrafluoroborates is 2:1:5.It is auxiliary in chemical reducing agent
Under the hydrothermal condition helped, reduction GO nanoscale twins are accumulated mutually with lamella and are connected restructuring, construct out with three-dimensional porous structure
Graphene hydrogel, be freeze-dried up to Graphene gel material.In an assembling process, due to 1- butyl 3- methylimidazoles four
Cation-π interaction between the glyoxaline cation of borofluoride molecule and graphene nanometer sheet π surfaces, hydrophilic 1- fourths
Base 3- methyl imidazolium tetrafluoroborate molecules are grafted to graphene assembly surface, so as to improve three-dimensional porous grapheme material
Can solution operability, by adjusting self assembly condition, it can be achieved that control to graphene nano lamella assembly behavior.
2nd, assembled using the porous graphene of hydrophilic hydrophilic 1- butyl 3- methyl imidazolium tetrafluoroborate molecular modifications
Body material good solvent-dispersible and film forming, can prepare porous graphene paper-like film by print process and print graphene
Paper；The shape and thickness for printing graphene paper can be adjusted by varying typography and the concentration of graphene dispersing solution；Make
Characterized with electron microscope porous graphene paper material microscopic appearance.Fig. 3 is that the scanning electron of printing graphene paper is shown
Micro mirror figure, it can be seen that graphene paper surface has the structure of porous multilayer, hole on microcosmic from scanning electron microscope diagram
Wall is to form the crosslinked netted framework of physics by overlapping or accumulation to be connected with each other by the graphene nanometer sheet of multilayer.
Wherein aperture size is from micron level to sub-micron rank.It is of the invention by hydrophilic 1- butyl when preparing graphene paper electrode
The graphene assembly of 3- methyl imidazolium tetrafluoroborates molecule grafting, which is distributed in aqueous solution, prepares graphite olefinic functionality slurry, leads to
Cross print process and prepare graphene paper electrode, wherein graphene paper electrode is working electrode, and printing carbon is to electrode, prints silver/chlorine
It is reference electrode to change silver, and the graphene test paper electrode structure of the three-electrode system of assembling is as shown in Figure 1.
Integrated graphene test paper electrode is prepared using silk screen print method.The basic principle of silk-screen printing is：Screen mask
The mesh of pattern part can pass through ink, and ink is deposited to substrate by pattern form;Remainder mesh on screen mask
It is blocked and stubbornly refuses that ink can be passed through, blank is formed on substrate, so as to obtains deposited the printed base plate of predetermined pattern shape.Tradition
Method for platemaking prepare and made a plate using manual hollow out, this method is complicated and time-consuming.This research work is made a plate using photoresist
Method, this method is first by silk screen（Such as nylon wire, polyester webs or stainless (steel) wire）Tighten and be fixed on screen frame, at the same light-sensitive emulsion is uniform
It is coated on silk screen, light-sensitive surface is formed, then by master slice（Position containing printing opacity）It is closely sealed on light-sensitive surface, exposed by certain time
Afterwards, the photosensitive adhesive curing of light transmission part, therefore this part mesh is closed on silk screen；And lighttight pattern part still maintains
Glue, peptization solution is removed, i.e., pattern mesh of different shapes is formed on silk screen.In silk-screen printing, ink is certain
Mesh is passed through under pressure, the electrode structure of halftone is printed on substrate, after high temperature drying cutting, miniature disposable is made
Electrode.The screen printing electrode that the screen printing electrode prepared using this method is largely produced in same batch, shape and structure etc.
It is uniform with higher uniformity, electrochemical properties.
This research is used as printed substrates using polyester film (PET), and with the conductive baseline of silver paste printed electrode bar, raising is led
Electrically, resistance and background current are reduced, the printing of carbon paste printing ink is covered on silver-colored rail, obstructs silver paste contact with solution to be measured,
Prevent silver paste exposure from aoxidizing in atmosphere so as to influence chemical property.Three electrode of silk-screen printing includes working electrode, to electrode
And reference electrode, using Graphene electrodes as working electrode, bismuth nano material is fixed on by electrode surface by electrodeposition process.It is right
Electrode and reference electrode use carbon electrode and silver/silver chloride electrode, when concentration of substrate is relatively low, are reduced frequently with silver/silver chlorate
The background noise of electrochemical reaction.
Print screen printing electrode the step of be：Electrode shape is designed by computer graphics and makes mask.Halftone
Prepare selection, the thickness of halftone ink film for usually considering mesh；Mesh is bigger, and fewer in the ink of substrate surface, resistance is bigger,
But smooth raising;And mesh is smaller, the ink of infiltration is more, is easier scumming, the mesh of this research selection halftone is 200
~250.Screen mesh printing plate, scraper and frictioning are cleaned with net washing water first, it is spare after volatilizing naturally；By printed substrates PET
It is spare after cooling in cleaning drying postposition baking oven when 120 DEG C of bakings 2 are small, to prevent PET sheet in subsequent high temperature heating process
Deformation, causes precision decline of printing electrode.
When printing electrode, the angle of inclination of scraper and halftone is adjusted to proper angle（Such as 75o）, and adjust halftone and base
Bottom is suitable distance（Such as 4 mm), halftone is fixed.Porous graphene dispersion liquid and conductive carbon paste, conductive silver paste are placed
On halftone, after examination print, adjusting air pressure makes electrode surface printing is smooth to be less than 5% with electrode resistance difference between batch.In PET sheet
After printing graphene, carbon-coating and silver layer, 110 DEG C dry 15 minutes, recycle slurry, are printed after the same method in insulating layer region
Insulating layer, 75 DEG C dry 10 minutes.Print electrode obtained in hydrochloric acid（7%）Solution Anodic Oxidation, by silver layer surface oxygen
Silver chlorate is turned to, silver/silver chloride reference electrode is made.
Embodiment 3
Referring to Fig. 1, a kind of graphene test paper electrode, it includes PET base 1（Polyester film）And printed thereon by typography
Working electrode 2, to electrode 3, reference electrode 4, silver conductive baseline 5 and insulating layer 6；Working electrode 2 is printing graphene,
It is printing carbon to electrode 3, reference electrode 4 is printing silver/silver chlorate；Working electrode 2 is located at the center of PET base 1, to electrode 3, ginseng
It is respectively separated than electrode 4 and is not in contact with each other positioned at the periphery of working electrode and three, working electrode 2, to electrode 3 and reference electrode
The 4 external silver conductive baselines 5 of difference；Insulating layer 6 is enclosed in the periphery to electrode 3, reference electrode 4 and it is internally formed work
Region；Insulating layer 6 at the same time covers silver conductive baseline 5（Continuous white box represents conductive path, i.e. insulating layer in Fig. 1
Lower working electrode 2, be uninterruptedly connected electrode 3 and reference electrode 4 with silver conductive baseline respectively）, obstruct silver conductive base
Line（Silver paste）With the contact of solution to be measured, prevent silver paste exposure from aoxidizing in atmosphere so as to influence chemical property；Silver conductive
Baseline 5 extends outward insulating layer 6 and forms contact jaw.
Embodiment 4
Referring to Fig. 1, a kind of heavy metal analysis graphene test paper electrode of supported active functional material, is tried in 1 graphene of embodiment
On the basis of paper electrode structure, in order to improve sensitivity and the reappearance in the analysis measurement of trace metal；Using（Electricity）Change
Be deposited on working electrode, which prints graphene surface modification, has heavy metal ion the bismuth film of special electro-chemical activity.
Common working electrode currently used for heavy metal analysis includes mercury film, liquid mercury electrode, gold electrode and platinum electrode etc..
And most common of which is mercury film electrode, contents of many kinds of heavy metal ion can detect（Such as copper, cadmium, lead, zinc）, detection sensitivity height,
Detection limit is low, favorable reproducibility etc., but this series of electrode can separate out poisonous and harmful substance mercury in detection process, which can be right
Environment pollutes, and endangers tester.Although gold electrode and platinum electrode can produce good volt-ampere to some metal ions and ring
Should, but their overall performance is not so good as mercury film.The electrochemical window in these electrode negative potential areas is relatively narrow, and background current is larger, this be by
Discontinuous change may occur in the surface activity of effective electrode area and electrodeposit metals, especially some metals occur altogether
During precipitation, often make dissolution peak reduce, rise or division, peak divide the reason for be that dissolution metal generates other things in electrode surface
Matter.Also someone has prepared antimony film, lead film, gallium film etc., although these films have reached the measure of Cucumber satisfied effect,
But chemical property is unstable, should not promote the use of.Somebody proposes the preplating based on surface ligand or amberplex and repaiies
Electrode is adornd, but they in the analysis measurement of trace metal, sensitivity and reappearance are bad.The toxicity of bismuth metal is extremely low, is recognized
To be a kind of environmentally protective metal.Research shows that bismuth metal has the electroanalysis performance similar with mercury, can be with many heavy metals
Ion forms the binary or multicomponent alloy similar to amalgam.In terms of heavy metal analysis, bismuth pole has overpotential height, background electricity
Flow low, electrochemical window mouth width, dissolution peak separator well, the advantages that stability is good, surface easily updates.In addition, bismuth pole to dissolved oxygen not
Sensitivity, therefore can be analyzed under conditions of not deoxygenation, operation complexity is enormously simplify, in terms of heavy metal ion super sensitivity detection
It is with a wide range of applications.
The present invention establishes supported active functional material on graphene paper electrode to research and develop high-performance sensors electrode to be oriented to
Efficiently controllable synthetic method, uses（Electricity）It is special that chemical deposition has heavy metal ion in porous graphene paper surface modification
The bismuth film of electro-chemical activity.Deposition bismuth film concretely comprises the following steps：First by a certain amount of bismuth nitrate（Bi(NO3)3）It is dissolved in vinegar
In acid buffering solution, the concentration of acetic acid is 0.2 mol/L（pH 4.6）, in obtained solution Bi3+ for 500 micrograms per litres/.
Graphene test paper electrode in embodiment 3 is placed in above-mentioned solution, deposits 300s under permanent potential -1.2V, in deposition process
It is stirred continuously, bismuth film can be formed by printing graphene surface in the working electrode to print electrode.
Embodiment 5
A kind of heavy metal detector based on electrochemistry, including electrochemical detection system and the three electrodes electricity of its input terminal connection
Chemical sensor, three-electrode electrochemical sensor use the heavy metal analysis graphite of the supported active functional material in embodiment 4
Alkene test paper electrode.
Electrochemical measuring technique is integrated on the basis of traditional electrochemical workstation in the present invention, is constructed miniature
Electrochemical detection system.Electro-chemical detection device employs high performance signal processor, high speed amplifier, high accuracy on hardware
Modulus and digital analog converter and hardware shield and interference protection measure, therefore very high signal resolution and survey can be reached when detecting
Accuracy of measurement.It can functionally realize the common cyclic voltammetry of electrochemistry, linear sweep voltammetry, staircase waveform voltammetry, Tafel
Figure, chronoamperometry, timing coulometry, differential pulse voltammetry, general pulse voltammetry, difference general pulse voltammetry, side
Ripple voltammetry, alternating voltammetry, current versus time curve, differential pulse current detecting, integrated pulse current detecting, controlling potential
It is electrolysed that storehouse is legal, AC impedance-time measurement, AC impedance-position measurement, chronoptentiometry, current scanning chronoptentiometry, more
The multi-mode operations such as galvanostatic pulse method, potentiometric stripping analysis, electrochemistry noise measurement, voltage-time curve and galvanostat.Its
Software has stronger analysis and control ability, suitable for carrying out dynamic analysis to Various Complex electrochemical system..This implementation
Example uses following miniature electrochemical analyser, the micro current signal produced for measuring three electrode sensors, hardware circuit
As shown in Fig. 2, it includes：
Power supply circuit, for each circuit power supply in system；
Control circuit, for the operation of each circuit in control system, receives electrochemical signals and handles；Control circuit can be selected
Select STM32 microcontrollers；
I/V conversion circuits, the current signal for three-electrode electrochemical sensor to be produced are converted into voltage signal；That is three electrodes
The signal that sensor produces be micro current signal, and current signal is first converted into method that voltage signal measures again to survey by need
Try the size of electric current；
Filter circuit, for removing the interference signal in transformed voltage signal；I.e. due to integrated circuit imperfection and
The influence of the factors such as the thermal noise of resistance, can make transformed voltage signal produce additional interference, if the interference signal does not filter out
And directly amplify, it is possible to flood useful signal, it is therefore necessary to filtering process is carried out before signal is amplified.
Amplifying circuit, for being amplified to voltage signal；Voltage signal i.e. by I/V conversions is faint voltage letter
Number, sampling is directly carried out to tiny signal and on the one hand requires the resolving power of sampling AD high, on the other hand external circuit is resisted
Interference requirement is higher.Therefore selection carries out voltage amplification before being AD converted, and improves the precision of sampling.
A/D convertor circuit, for voltage signal to be converted into digital signal by analog signal；
Bipolarity generation circuit, for producing the circuit of positive and negative bipolar voltage；That is the potential of electrode need just have it is negative, because
This needs a circuit that can produce positive and negative bipolar voltage, which can be programmed to produce different wave
Voltage signal.
Potentiostatic circuit, the potential for keeping three-electrode electrochemical sensor working electrode are maintained at steady state value；Exist
During working sensor, due to the influence of polarization, the offset of electrode potential can be caused, so as to cause the output of sensor
It is unstable, it is therefore desirable to keep the potential of working electrode to be maintained at steady state value.
Serial ports output circuit, for exporting printing function by serial ports, will collect data and is depicted as curve by processing；
That is the effect of the partial circuit is to export printing function by serial ports, will collect data and is depicted as curve by processing, so that
Judge the performance of instrument.
Display circuit, for being shown the signal collected by liquid crystal display；
Bipolarity generation circuit, A/D convertor circuit, serial ports output circuit and display circuit are connected with control circuit respectively, permanent electricity
Position circuit is connected with bipolarity generation circuit, and I/V conversion circuits, filter circuit, amplifying circuit are connected with A/D convertor circuit successively；
Potentiostatic circuit, I/V conversion circuits are connected with three-electrode electrochemical sensor；Control circuit, I/V conversion circuits, filtered electrical
Road, amplifying circuit, A/D convertor circuit, bipolarity generation circuit, potentiostatic circuit, serial ports output circuit and display circuit with
Power supply circuit connects.
Embodiment 6
The foundation of the heavy metal detector electrochemical detection method based on electrochemistry is as follows in embodiment 5：
The present invention uses anodic stripping voltammetry（Anodic Stripping Voltammetry, ASV）Detect heavy metal from
Son, such as differential pulse ASV and square-wave pulse SWASV.
ASV technologies are electrochemistry of the 1920s by a kind of Jaroslav Heyrovsky heavy metal ion invented
Analysis method.It is simple with high sensitivity, apparatus, it is easy to accomplish the advantages that automation is concerned by people.It is sent out
Bright person Jaroslav Heyrovsky obtain Nobelization of nineteen fifty-nine because of the outstanding contributions in terms of detection of heavy metal ion
Learn prize.
The working mechanism of ASV methods is first to be enriched to heavy metal ion to be measured on working electrode, then make current potential by
Negative sense is just scanned, and makes the heavy metal ion from electrode dissolution, records the Current-potential curve of the process in leaching.Certain
In the range of, the peak height of Current-potential curve and the concentration of heavy metal ion heavy metal ion in a linear relationship and different exist
There is different spike potentials in identical electrolyte.So dissolution peak current and spike potential can be used as and qualitatively and quantitatively analyze
The basis of concentration of heavy metal ion.Up to the present, ASV methods can measure more than 40 kinds of heavy metal element, it can be fast
Micro heavy metal ion in speed detection sample, and detection sensitivity is very high.Since ASV methods have required instrument and equipment letter
The advantages that single, easy to operate.So very extensive application is obtained in the analysis of ultrapure material and environmental monitoring and analysis.
Heavy metal ion includes electrolysis enrichment and electrolysis two processes of dissolution in ASV detection water.The first step is enrichment process,
, should in solution when the potential of electrode exceedes the evolution or deposition potential of certain heavy metal ion by reduction potential plus on the working electrode (s
Metal ion species will be reduced to metal and electroplate on the surface of working electrode, when reduction potential application obtains on the working electrode (s
Between longer metal being plated on electrode surface for restoring it is more.Second step is then electrolysis process in leaching, when enough
When metal layer is plated on working electrode surface, potential is increased to working electrode with constant speed, which will on the working electrode (s
Dissolution（Aoxidize）.The species of metal can be identified according to the position of oxidation potential, and the difference of oxidation potential can be passed through
It is carried out at the same time the detection of contents of many kinds of heavy metal ion.Pass through calculating current peak height or peak area and the standard solution ratio under the same terms
To calculating the concentration of heavy metal ion in sample.
Graphene paper electrode is connected by this project with miniature electrochemical analyser first, in order to ensure electrode and work station are complete
Full connection and errorless, after line connects, the corresponding resistance in conducting wire both ends is surveyed using electronic multimeter respectively, see resistance value it is no
Within zone of reasonableness.
After the inspection of above-mentioned connection is errorless, electrochemical workstation is opened, is then drawn with the pipettor of corresponding range certain
The standard solution of Cd2+, Pb2+ and Cu2+ of concentration known, are equably added dropwise the working electrode surface of graphene test paper electrode.This
Project differential pulse ASV technology for detection heavy metal ion.Two stages are specifically divided into, first stage Cd2+, Pb2+ and Cu2+'s
Deposition, has investigated the influence of different enrichment times and accumulating potential for electro-deposition, static a period of time after deposition, optimization
Settling time and resting potential.Second stage Cd2+, Pb2+ and Cu2+ dissolution, this experimental selection is differential pulse ASV, optimization
Electrochemical workstation is set（Miniature electrochemical analyser）Starting voltage be -0.8 V, final voltage is -0.1 V, pulse width
Spend 50 mV, 50 ms of pulse width.After terminating scanning, in order to make electrode regeneration, it is necessary to electric to perseverance of the Graphene electrodes in 0.1 V
Position 30 s of lower stirring and washing.
First, the optimization of experiment condition
（1）Enrichment time
Test result indicates that enrichment time is relatively low less than 30 s Cd2+, the peak current at Pb2+ and Cu2+ dissolutions peak, it is difficult to measure；
When enrichment time is more than 30 s, with enrichment time, the dissolution peak current of Cd2+, Pb2+ and Cu2+ linearly increase；Work as enrichment
When time is more than 360 s, peak current change tends to be slow, illustrates that Cd2+, Pb2+ and Cu2+ have been reached in the enrichment of electrode surface
To saturation.120 s can meet that analysis requires in this experimentation, and can reduce analysis time, thus select enrichment time for
120 s。
（2）Accumulating potential
When accumulating potential changes between -1.0 ~ 0.2 V, shifting is born with current potential, the dissolution peak current of Cd2+, Pb2+ and Cu2+ by
It is cumulative to add.But the dissolution peak current increase of Cd2+, Pb2+ and Cu2+ are slow from -1.0 V, when being defeated by -1.0 V, the weight of electrode
Existing property reduces, this is because in the liquid of bottom impurity peaks interference.Therefore -1.0 V of selection are accumulating potential.
（3）The influence of settling time and resting potential
Tranquillization process can make Cd2+, Pb2+ and Cu2+ become uniform in the bismuth nano-material surface of graphene surface, improve analysis
As a result repeatability.Test result indicates that when settling time changes in the range of 0 ~ 75 s, with the increase Cd2 of settling time
+, the dissolution peak current of Pb2+ and Cu2+ gradually increase, from 60 s, peak current hardly changes, and peak shape tends towards stability, thus this
Experimental selection settling time is 60 s.Experiment finds that the peak current of resting potential Cd2+, Pb2+ and Cu2+ in -1.0 V are maximum,
Peak shape is best, therefore it is resting potential to select -1.0 V.
2nd, the influence of interfering ion
Relative standard deviation is allowed to be measured no more than scholar 5% with the standard solution of 100 nM zinc, it is following in bottom liquid is measured
Common ion is on measurement result without influence：1000 times of K+、Ca2+、Na+、Mg2+、NH4 +、Fe2+、Fe3+、A13+、Bi3+、Mn2+、Cr3 +、NO3 -、SO4 2-、Cl-And starch, glucose, ascorbic acid, dextrin, carboxyrnethyl starch sodium, odium stearate magnesium do not disturb, inspection
Survey relative standard deviation（RSD）Less than 5%, as shown in table 1：
3rd, different heavy metal ion working curves and test limit
For the linear working range and test limit of inspecting electrode, the heavy metal copper using differential pulse ASV to various concentrations
Ion is repeatedly measured respectively, and Fig. 4 is 100 nmol/L, 1 μm of ol/L, 2 μm of ol/ under the experiment condition of optimized parameter
L, 5 μm of ol/L, 8 μm of ol/L, 10 μm of ol/L, the standard heavy ion Stripping Voltammetry of 15 μm of ol/L and 20 μm of ol/L concentration
Curve map.
Referring to Fig. 5, with the increase of heavy ion concentration in solution, the Stripping Voltammetry response also increasing in a linear relationship on electrode
Greatly, its linear working range is 10 nmol/L -20 μm of ol/L.
(1) Cd2+ equations of linear regression y (Cd2+)=- 0.114+0.536x, linearly dependent coefficient R2=0.999,
15 nmol/L of detection limit
(2) Pb2+ equations of linear regression y (Pb2+)=0.051+0.748x, linearly dependent coefficient R2=0.995, detection
Limit 10 nmol/L
(3) Cu2+ equations of linear regression y (Cu2+)=- 0.249+0.389x, linearly dependent coefficient R2=0.996, inspection
20 nmol/L (y of rising limit: current/mA cm-2, x: concentration/μmol/L).
4th, actual sample detects：
Using the content of heavy metal ion in homemade electrode and supporting electrochemical analyser test lake water sample, as a result such as table 2
Shown, 10 retest rate of recovery are less than 5% for 92.5%, RSD, it was demonstrated that the graphene paper electrode and electrochemistry of this Project-developing
Analyzer has higher accuracy and practicality.
The above, is only the exemplary embodiments of the present invention, those skilled in the art is possibly also with above-mentioned elaboration
Equivalent technical solution is changed or be revised as to technical solution to the present invention.Therefore, according to technical scheme
Any simple modification carried out or substitute equivalents, belong to the greatest extent the scope of protection of present invention.
Claims (10)
1. it is a kind of based on graphene test paper electrode structure electrochemical heavy metals detector, including electrochemical detection system and its
The three-electrode electrochemical sensor of input terminal connection, it is characterised in that：The three-electrode electrochemical sensor is printed for graphene
Paper electrode；Described graphene printing paper electrode includes PET base and the working electrode printed thereon by typography, right
Electrode, reference electrode, silver conductive baseline and insulating layer；The working electrode is printing graphene, and described is print to electrode
Brush carbon, the reference electrode are printing silver/silver chlorate；The working electrode is located at PET base center, described to electrode, reference
Electrode is respectively separated to be not in contact with each other positioned at the periphery of working electrode and three, the working electrode, to electrode and reference electrode
External silver conductive baseline respectively；The insulating layer is enclosed in the periphery to electrode, reference electrode and it is internally formed work
Region；The insulating layer at the same time covers the silver conductive baseline, and the silver conductive baseline extends outward insulation
Layer forms contact jaw；The working electrode surface deposition has one layer of bismuth film.
2. it is a kind of based on graphene test paper electrode structure electrochemical heavy metals detector, including electrochemical detection system and its
The three-electrode electrochemical sensor of input terminal connection, it is characterised in that：The three-electrode electrochemical sensor is printed for graphene
Paper electrode；The preparation method of the graphene printing paper electrode comprises the following steps：
（1）The preparation of three-dimensional porous graphene assembly：It is 80mg/ that graphene oxide, which is distributed in deionized water, and forms concentration
The graphene oxide dispersion of ml, then adds dopamine and hydrophilic imidazole ion liquid 1- butyl 3- methylimidazole tetrafluoro boron
Hydrochlorate carries out hydro-thermal reaction, and the graphene oxide, dopamine, the mass ratio of 1- butyl 3- methyl imidazolium tetrafluoroborates are
1.5-2.5:1:4-6；When the hydro-thermal reaction is 85-95 DEG C of isothermal reaction 5-7 small；Hydro-thermal reaction obtains having three-dimensional porous knot
The graphene hydrogel of structure, is then freeze-dried up to graphene aerogel；
（2）By step（1）Obtained graphene aerogel, which is distributed in aqueous solution, prepares graphite olefinic functionality slurry, while configuration is led
Electrical carbon is starched and conductive silver paste, and the graphene test paper electrode of the three-electrode system of assembling, wherein graphite are then prepared by print process
Alkene paper electrode is working electrode, and it is reference electrode to electrode, printing silver/silver chlorate that printing carbon, which is,；
（3）By step（2）Obtained working electrode surface deposits one layer of bismuth film.
3. the electrochemical heavy metals detector according to claim 1 or 2 based on graphene test paper electrode structure, the electricity
Chemical detection system is for electrochemical workstation or including with lower structure：
Power supply circuit, for each circuit power supply in system；
Control circuit, for the operation of each circuit in control system, receives electrochemical signals and handles；
I/V conversion circuits, the current signal for three-electrode electrochemical sensor to be produced are converted into voltage signal；
Filter circuit, for removing the interference signal in transformed voltage signal；
Amplifying circuit, for being amplified to voltage signal；
A/D convertor circuit, for voltage signal to be converted into digital signal by analog signal；
Bipolarity generation circuit, for producing the circuit of positive and negative bipolar voltage,
Potentiostatic circuit, the potential for keeping three-electrode electrochemical sensor working electrode are maintained at steady state value；
Serial ports output circuit, for exporting printing function by serial ports, will collect data and is depicted as curve by processing；
Display circuit, for being shown the signal collected by liquid crystal display；
The bipolarity generation circuit, A/D convertor circuit, serial ports output circuit and display circuit respectively with the control circuit
Connection, the potentiostatic circuit are connected with bipolarity generation circuit, and the I/V conversion circuits, filter circuit, amplifying circuit are successively
It is connected with A/D convertor circuit；The potentiostatic circuit, I/V conversion circuits are connected with three-electrode electrochemical sensor；The control
Circuit processed, I/V conversion circuits, filter circuit, amplifying circuit, A/D convertor circuit, bipolarity generation circuit, potentiostatic circuit, string
Mouth output circuit and display circuit are connected with power supply circuit.
4. the electrochemical heavy metals detector according to claim 1 based on graphene test paper electrode structure, its feature exist
In the preparation method of the graphene printing paper electrode comprises the following steps：
（1）The preparation of three-dimensional porous graphene assembly：It is 80mg/ that graphene oxide, which is distributed in deionized water, and forms concentration
The graphene oxide dispersion of ml, then adds dopamine and hydrophilic imidazole ion liquid 1- butyl 3- methylimidazole tetrafluoro boron
Hydrochlorate carries out hydro-thermal reaction, and the graphene oxide, dopamine, the mass ratio of 1- butyl 3- methyl imidazolium tetrafluoroborates are
1.5-2.5:1:4-6；When the hydro-thermal reaction is 85-95 DEG C of isothermal reaction 5-7 small；Hydro-thermal reaction obtains having three-dimensional porous knot
The graphene hydrogel of structure, is then freeze-dried up to graphene aerogel；
（2）By step（1）Obtained graphene aerogel, which is distributed in aqueous solution, prepares graphite olefinic functionality slurry, while configuration is led
Electrical carbon is starched and conductive silver paste, and the graphene test paper electrode of the three-electrode system of assembling, wherein graphite are then prepared by print process
Alkene paper electrode is working electrode, and it is reference electrode to electrode, printing silver/silver chlorate that printing carbon, which is,；
（3）By step（2）Obtained working electrode surface deposits one layer of bismuth film.
5. the preparation method of the preparation method of the graphene printing paper electrode according to claim 2 or 4, it is characterised in that
The step（1）In graphene oxide be prepared by following steps：
Cold stage：First by the concentrated sulfuric acid that 230 milliliters of mass fractions are 98%, 0 DEG C is cooled to；Then in the feelings quickly stirred
The mixture of 10 grams of natural graphite powders and 5 grams of sodium nitrate is added under condition；30 grams of potassium permanganate are then slowly added into, control temperature
When reaction 2 is small in the range of 10 ~ 15 DEG C；
Middle thermophase：By reacting liquid temperature control in the range of 32-38 DEG C, continue in the case of stirring reaction 2 it is small when；
Hot stage：460 ml deionized waters are continuously slowly added into reaction solution, temperature is risen to 98 DEG C, dimension
Hold and react 30 minutes at this temperature；Again 1400 milliliters are diluted to deionized water；
Then the H of 30 milliliters of 5 % of mass fraction is added into reaction solution2O2, it was observed that color becomes glassy yellow, filter while hot
To graphene oxide crude product；
Then the HCl/water solution that graphene oxide crude product mass fraction is 5% is rinsed, then be washed with deionized repeatedly extremely
There is no SO4 in filtrate2-Ion；Adding 3200 ml deionized waters into graphene oxide crude product again, to obtain graphene oxide molten
Liquid；
Then pass through multiple centrifugal concentrating graphene oxide solution；By repeatedly washing, the pH value of graphene oxide solution is washed
To neutrality, finally by obtaining solid oxidation graphene after centrifugation, washing, vacuum drying.
6. the electrochemical heavy metals detector based on graphene test paper electrode structure according to claim 2 or 4, its feature
It is, the print process step is：
（1）The electrode shape that paper electrode is printed according to graphene makes halftone；
（2）Halftone is adjusted with substrate to suitable distance, halftone is fixed；
（3）Graphite olefinic functionality slurry and conductive carbon paste, conductive silver paste are placed on halftone, air pressure is adjusted and stone is printed in substrate
Black alkene layer, carbon-coating and silver layer；Dry and recycle slurry,
（4）After the same method insulating layer, drying are printed in insulating layer region；
（5）Print electrode obtained in hydrochloric acid solution Anodic Oxidation, silver layer surface is oxidized to silver chlorate, silver/chlorine is made
Change silver-colored reference electrode.
7. the electrochemical heavy metals detector according to claim 6 based on graphene test paper electrode structure, its feature exist
In：
The step（1）The mesh of middle halftone is 200 ~ 250；
The step（3）Middle drying is dried 15 minutes for 110 DEG C；
The step（3）It is middle to use polyester film as printed substrates；
The step（3）Middle printing holding electrode surface printing is smooth and electrode resistance difference between batch is less than 5%；
The step（4）Middle drying is dried 10 minutes for 175 DEG C；
The step（5）Middle hydrochloric acid solution mass concentration is 7%.
8. the electrochemical heavy metals detector based on graphene test paper electrode structure according to claim 1,2 or 4, it is special
Sign is that the deposition bismuth film comprises the following steps：
（1）Bismuth nitrate is dissolved in hac buffer, Bi in obtained solution3+Concentration is 400-600 micrograms per litres；
（2）The graphene printing paper electrode that print process obtains is placed in above-mentioned solution, is deposited under permanent potential -1.4 ~ -1.0V
200-400s, is stirred continuously in deposition process, and printing graphene surface in the working electrode of graphene test paper electrode forms bismuth
Film.
9. the detection method of any heavy metal detectors based on electrochemistry of claim 1-8, it is characterised in that including such as
Lower step：
（1）The heavy metal analysis graphene test paper electrode of supported active functional material is connected with electrochemical detection system first；
（2）Electrochemical detection system is opened, then drawing prepare liquid with the pipettor of corresponding range is added dropwise graphene test paper electrode
Working electrode surface；
（3）By differential pulse ASV technology for detection heavy metal ion, two stages, first stage heavy metal ion are specifically divided into
Deposition, deposition voltage is the V of -1.0 V ~ -0.7, and sedimentation time is 120-240 s；It is static after deposition, tranquillization electricity
The position V of -1.0 V ~ -0.7, settling time is 40 ~ 90 s.
10. the detection method of the heavy metal detector based on electrochemistry according to claim 9, it is characterised in that described heavy
Product voltage is -1.0 V, and the sedimentation time is 120s；The V of resting potential -1.0, the settling time are 60 s；Institute
State step（3）The starting voltage of differential pulse ASV is -0.8 V, and final voltage is -0.1 V, 50 mV of impulse amplitude, and pulse is wide
Spend 50 ms.
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