CN107632051B - Working electrode for heteropoly acid base electrochemical sensor - Google Patents
Working electrode for heteropoly acid base electrochemical sensor Download PDFInfo
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Abstract
A working electrode for a heteropolyacid-based electrochemical sensor. The invention belongs to the technical field of electrochemical sensors, and particularly relates to a working electrode for a heteropoly acid based electrochemical sensor. The invention aims to solve the problems of complex preparation, slow response speed and poor sensitivity of the current enzyme-free sensor for detecting xanthine and uric acid. The product is as follows: PEI/(PMo) externally wrapped by GCE electrode and GCE electrode6W6/RGO‑CeO2@Pt)6Forming a modified film; the electrochemical sensor constructed by the working electrode has good detection performance on xanthine and uric acid.
Description
Technical Field
The invention belongs to the technical field of electrochemical sensors, and particularly relates to a working electrode for a heteropoly acid based electrochemical sensor.
Background
Xanthine is a purine base widely distributed in organs and body fluids of human bodies and other organisms, and the level of purine content in human bodies directly reflects the health condition of human bodies. Xanthine oxide in human tissues readily oxidizes hypoxanthine into xanthine and further into uric acid, during which superoxide radical O is produced2 ·-Accompanied by superoxide,·The generation of OH free radicals, which are important factors for the occurrence of various diseases such as pulmonary fibrosis, hypertension, Parkinson disease and the like, can accurately early warn the occurrence of the diseases by accurately measuring the content of xanthine. Uric acid as trioxypurine is a purine metabolic final product in a human body, and if the content of uric acid in body fluid is too high, various diseases such as diabetes, obesity and the like can be caused. Therefore, the search for a suitable catalyst led to the establishment of a catalystThe method with high sensitivity is very important for detecting xanthine and the metabolite uric acid thereof.
Polyoxometallate is increasingly attracting attention as a green catalyst due to excellent physicochemical properties and potential application prospects. Including the high stability of most of them in redox state, the tunable modification of redox potential by changing hetero-and/or counter-ions while keeping their structure unchanged, the diversity of transition metal cations that can be incorporated into the heteropolyanion structure and the possibility of multiple electron transfer. Therefore, polyoxometallate with various structures and excellent properties is added into a multilayer film as an inorganic component, so that the film material can be endowed with more excellent functional characteristics, and the polyoxometallate is a new research hotspot in the field of polyacid and materials.
Graphene is widely used for research of electrochemical sensors, and has the characteristics of large specific surface area, extremely strong conductivity, semiconductor characteristics, high chemical stability and the like. The effective area of the sensitive membrane is increased through the RGO, the electron transfer rate is improved, and the sensitivity and the electrocatalytic activity of the sensor can be greatly enhanced. In addition, the excellent electrical properties of RGO make it have a very great potential application value as an additive phase of a composite nano material, and the application of RGO in the aspect of electrochemical analysis is very attractive. Therefore, it is very important to combine the high-selectivity sensing technology with the high-sensitivity graphene to construct a sensor for practical detection.
The metal nano particles have wide application in the field of catalysis, and the addition of the metal nano particles can increase the surface active sites of the composite film and further improve the electron transmission rate of the composite film, so that the sensing performance of the electrochemical sensor is enhanced, but the expensive price of Pt always restricts the application of the Pt. Cerium oxide (CeO)2) Has received much attention in the research of selective catalytic reduction technology catalysts due to the excellent characteristics of oxidation-reduction, oxygen storage, etc. Meanwhile, cerium dioxide is an electrochemical catalyst with excellent performance, and can effectively realize the electrocatalysis of biological micromolecules. Therefore, combining ceria with platinum is a strong combination of options.
Disclosure of Invention
The invention aims to solve the problems of low detection speed and poor sensitivity of the current enzyme-free sensor for detecting xanthine and uric acid which is a metabolite of the xanthine, and provides a working electrode for a heteropoly acid base electrochemical sensor.
The working electrode for the heteropoly acid based electrochemical sensor is composed of a GCE electrode and PEI/(PMo) coated outside the GCE electrode6W6/RGO-CeO2@Pt)nThe modified membrane is composed of a GCE electrode and PEI: polyethylene layer, PMo6W6: phosphomolybdotungstic heteropoly acid layer, RGO-CeO2@ Pt: and the reduced graphene oxide layer is loaded with cerium dioxide @ platinum alloy nanoparticles. With PMo6W6Layer and RGO-CeO2The @ Pt layer is a cyclic unit, cycled n times, where n =1 ~ 6.
The PEI/(PMo)6W6/RGO-CeO2@Pt)nThe thickness of the modified film was 0.33. mu.m ~ 1.46.46. mu.m.
The heteropoly acid is Keggin type phosphomolybdotungstic heteropoly acid with molecular formula of H3PMo6W6O40·mH2O, m =36 ~ 42, with an atomic ratio of P: Mo: W of 1: 6: 6.
The polyethyleneimine layer is obtained by modifying a polyethyleneimine solution with the concentration of 9mmol/L ~ 13mmol/L by a GCE electrode, and the modification time is 15min ~ 20 min.
The phosphomolybdic tungsten heteropoly acid layer in each cycle is obtained by modifying a GCE electrode in a phosphomolybdic tungsten heteropoly acid solution with the concentration of 5mg/L ~ 8mg/L, and the modification time is 15min ~ 20 min.
The reduced graphene oxide layer loaded with cerium dioxide @ platinum alloy nanoparticles in each cycle is modified by a GCE electrode to RGO-CeO with the concentration of 6mg/L ~ 10mg/L2The modification time was 15min ~ 20min, obtained in the @ Pt suspension.
The RGO-CeO2The concentration ratio of ceria to platinum alloy nanoparticles in the @ Pt suspension was (0.1 ~ 0.11.11) mmol/L: 0.01 mmol/L.
The cerium dioxide @ platinum alloy nanoparticles in the reduced graphene oxide layer loaded with the cerium dioxide @ platinum alloy nanoparticles in each cycle are spherical nanoparticles, and the particle size is 18nm ~ 22 nm.
The reduced graphene oxide in the reduced graphene oxide layer loaded with the cerium dioxide @ platinum alloy nanoparticles in each cycle is of a two-dimensional nanosheet structure, and the concentration is 5mg/mL ~ 6 mg/mL.
The invention has the beneficial effects that:
compared with the traditional enzyme-free sensor, the working electrode for the heteropoly acid-based electrochemical sensor is constructed. Solves the problems of low detection speed, poor sensitivity and the like in the detection of xanthine and uric acid in practical application. The main reason is that the synergistic effect of cerium dioxide @ platinum alloy nano particles, heteropoly acid and graphene promotes the transmission rate of electrons on the surface of the electrode and enlarges the active adsorption sites of small biological molecules on the surface of the electrode, so that the electrocatalysis performance of the electrode is greatly improved.
Drawings
FIG. 1 shows PEI/(PMo) on GCE electrode obtained in experiment6W6/RGO-CeO2@Pt)6Scanning electron microscope images of the cerium dioxide @ platinum alloy nanoparticles in the modified film;
FIG. 2 shows PEI/(PMo) on GCE electrode obtained in experiment6W6/RGO-CeO2@Pt)6A scanning electron microscope image of reduced graphene oxide loaded with cerium dioxide @ platinum alloy nanoparticles in the modification film;
FIG. 3 shows PEI/(PMo) on GCE electrode obtained in experiment6W6/RGO-CeO2@Pt)6Scanning electron micrographs of the modified film;
FIG. 4 shows PEI/(PMo) on GCE electrode obtained in experiment6W6/RGO-CeO2@Pt)6A full spectrum of the X-ray photoelectron spectrum of the modified film in the range of 0 ~ 960 eV;
FIG. 5 is a cyclic voltammogram showing that the electrochemical sensor catalyzes the oxidation reaction of xanthine and uric acid simultaneously in the first verification test; wherein 1 represents cyclic voltammograms in which xanthine and uric acid at a concentration of 0 μ M were added, 2 represents cyclic voltammograms in which xanthine and uric acid at a concentration of 10 μ M were added, 3 represents cyclic voltammograms in which xanthine and uric acid at a concentration of 20 μ M were added, 4 represents cyclic voltammograms in which xanthine and uric acid at a concentration of 30 μ M were added, and 5 represents cyclic voltammograms in which xanthine and uric acid at a concentration of 40 μ M were added, respectively;
FIG. 6 is a graph showing the response current to concentration of added xanthine during catalysis of xanthine by the electrochemical sensor in test (one);
fig. 7 is a graph showing the relationship between the response current and the added uric acid concentration during the process of catalyzing uric acid by the electrochemical sensor in the test (i).
Detailed Description
The first embodiment is as follows: the working electrode for the heteropoly acid based electrochemical sensor of the embodiment is PEI/(PMo) coated outside a GCE electrode and a GCE electrode6W6/RGO-CeO2@Pt)nThe modified membrane is composed of a GCE electrode and PEI: polyethylene layer, PMo6W6: phosphomolybdotungstic heteropoly acid layer, RGO-CeO2@ Pt: and the reduced graphene oxide layer is loaded with cerium dioxide @ platinum alloy nanoparticles. With PMo6W6Layer and RGO-CeO2The @ Pt layer is a unit of one cycle, and is cycled n times.
The second embodiment is different from the first embodiment in that n =1 ~ 6, and other steps and parameters are the same as those of the first embodiment.
The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: the PEI/(PMo)6W6/RGO-CeO2@Pt)nThe thickness of the modified film is 0.33 μm ~ 1.46.46 μm other steps and parameters are the same as those of the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: the heteropoly acid is Keggin type phosphomolybdotungstic heteropoly acid with molecular formula of H3PMo6W6O40·mH2O, m =36 ~ 42, P is Mo, WThe sub ratio is 1: 6: 6. other steps and parameters are the same as those in one of the first to third embodiments.
Fifth embodiment is different from the first to fourth embodiments in that the polyethyleneimine layer is obtained by modifying a polyethyleneimine solution with a concentration of 9mmol/L ~ 13mmol/L by using a GCE electrode, and the modification time is 15min ~ 20 min.
Sixth embodiment, the difference between the first embodiment and the fifth embodiment is that the phosphomolybdic tungsten heteropoly acid layer in each cycle is obtained by modifying a phosphomolybdic tungsten heteropoly acid solution with the concentration of 5mg/L ~ 8mg/L by using a GCE electrode, and the modification time is 15min ~ 20 min.
Seventhly, the embodiment is different from the first to sixth embodiments in that the reduced graphene oxide layer loaded with ceria @ platinum alloy nanoparticles in each cycle is RGO-CeO modified by GCE electrode at a concentration of 6mg/L ~ 10mg/L2The modification time is 15min ~ 20min, obtained in the Pt suspension, other steps and parameters are the same as those of the first to sixth embodiments.
The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: the RGO-CeO2The concentration ratio of ceria to platinum alloy nanoparticles in the Pt suspension is (0.1 ~ 0.11.11) mmol/L: 0.01 mmol/L.
Ninth embodiment, the difference between this embodiment and the first to eighth embodiments is that the ceria @ platinum alloy nanoparticles in the reduced graphene oxide layer loaded with the ceria @ platinum alloy nanoparticles in each cycle are spherical nanoparticles, and the particle size is 18nm ~ 22 nm.
Tenth embodiment, the difference between this embodiment and one of the first to ninth embodiments is that reduced graphene oxide in the reduced graphene oxide layer loaded with ceria @ platinum alloy nanoparticles per cycle has a two-dimensional nanosheet structure and a concentration of 5mg/mL ~ 6mg/mL, and other steps and parameters are the same as those in one of the first to ninth embodiments.
The concrete implementation mode eleven: the preparation method of the working electrode for the heteropoly acid based electrochemical sensor of the embodiment comprises the following steps:
firstly, preparing a Keggin type phosphomolybdic tungsten heteropoly acid solution: combining Na2WO4·2H2O、Na2MoO4·2H2O and NaH2PO4·2H2Dispersing O into 65mL ~ 70mL distilled water, keeping reacting for 2h ~ 3h at 80 ℃ ~ 85 ℃ and maintaining reaction for 33 h ~ 35mL hydrochloric acid solution with the mass fraction of 22% and ~ 24% into the solution I, and extracting with excessive diethyl ether to obtain Keggin type phosphomolybdotungstic heteropoly acid (PMo)6W6A solution;
in the first step2WO4·2H2O、Na2MoO4·2H2O and NaH2PO4·2H2The molar ratio of O is 2: 2: 0.9 ~ 1.1.1;
in the first step2WO4·2H2The molar concentration of O is 0.6M ~ 0.7.7M;
in the first step2MoO4·2H2The molar concentration of O is 0.6M ~ 0.7.7M;
the NaH in the first step2PO4·2H2The molar concentration of O is 0.3M ~ 0.35.35M;
secondly, preparing a reduced graphene oxide suspension loaded with cerium dioxide @ platinum alloy nanoparticles: adding Ce (NO) at room temperature3)3Aqueous solution and K2PtCl4The aqueous solution was added dropwise to 20ml of H at the same time2Adding graphene oxide suspension into O solution at a dropping speed of 1 drop/s ~ 3 drop/s, changing the color of the water solution from colorless to black, and keeping the reaction at room temperature for 5min ~ 7min, adding graphene oxide suspension into the solution at the temperature of 65 ℃, ~ 75 ℃, continuously stirring the mixture for 55 ~ 60 min at a magnetic stirring speed of 40r/min ~ 50r/min, and obtaining the supported dioxideReduced graphene oxide suspension of cerium @ platinum alloy nanoparticles, marked as RGO-CeO2@ Pt suspension;
step two2Ce (NO) in O solution3)3And K2PtCl4The molar ratio is 10: 1 ~ 1.2.2;
ce (NO) in step two3)3Ce (NO) in aqueous solution3)3The molar concentration is 0.1M ~ 0.12.12M;
said K in step two-2PtCl4K in aqueous solution2PtCl4The molar concentration is 0.01M ~ 0.012.012M;
secondly, the concentration of graphite oxide in the graphene oxide suspension is 5mg/mL ~ 6 mg/mL;
thirdly, based on heteropoly acid/graphene/CeO2The working electrode for the electrochemical sensor of @ Pt is prepared by firstly immersing the GCE electrode in the aqueous solution of polyethyleneimine, soaking for 20h ~ 24h, taking out, washing with deionized water, and then washing with N2Drying; ② immersing in the PMo obtained in the step one6W6Soaking in the solution for 15min ~ 20min, taking out, washing with deionized water, and adding N2Drying; ③ immersing in the RGO-CeO obtained in the second step2Soaking in @ Pt suspension for 15min ~ 20min, taking out, washing with deionized water, and adding N2Blowing, repeating the operation of the step ~ for n times to obtain the product based on heteropoly acid/graphene/CeO2Working electrode for electrochemical sensors of @ Pt, noted PEI/(PMo)6W6/RGO-CeO2@Pt)nModified GCE electrode, n =1 ~ 6;
the concentration of the polyethyleneimine aqueous solution in the step three is 9mmol/L ~ 13 mmol/L.
The working electrode for the electrochemical sensor prepared by the method has the advantages of simple preparation, quick response and the like, and is sensitive to the detection of xanthine and uric acid. The main reason is that the synergistic effect of cerium dioxide @ platinum alloy nano particles, heteropoly acid and graphene promotes the transmission rate of electrons on the surface of the electrode and enlarges the active adsorption sites of small biological molecules on the surface of the electrode, so that the electrocatalysis performance of the electrode is greatly improved.
The specific implementation mode twelve: the present embodiment is different from the first embodiment in that: in the first step2WO4·2H2O、Na2MoO4·2H2O and NaH2PO4·2H2The molar ratio of O is 2: 2: 1. other steps and parameters are the same as those in the eleventh embodiment.
The specific implementation mode is thirteen: this embodiment is different from the embodiment eleven or twelve: in the first step2WO4·2H2The molar concentration of O is 0.65M. Other steps and parameters are the same as in the eleventh or twelfth embodiment.
The specific implementation mode is fourteen: this embodiment is different from one of the eleventh to thirteenth embodiments in that: in the first step2MoO4·2H2The molar concentration of O is 0.65M. Other steps and parameters are the same as those in one of the eleventh to thirteenth embodiments.
The concrete implementation mode is fifteen: this embodiment is different from the eleventh to fourteenth embodiment in that: the NaH in the first step2PO4·2H2The molar concentration of O is 0.325M. Other steps and parameters are the same as those in one of the eleventh to the fourteenth embodiments.
The specific implementation mode is sixteen: this embodiment differs from one of the eleventh to fifteenth embodiments in that: in the first step, Na is added2WO4·2H2O、Na2MoO4·2H2O and NaH2PO4·2H2O is dispersed into 67mL of distilled water, and the reaction is maintained for 2.5h at 82 ℃; ② 34mL of hydrochloric acid solution with the mass fraction of 23 percent is added into the (I), and the color of the solution turns to bright yellow. Extracting with excessive ether to obtain Keggin type phosphomolybdotungstic heteropoly acid marked as PMo6W6And (3) solution. Other steps and parameters are the same as in one of the eleventh to fifteenth embodiments.
Seventeenth embodiment: this embodiment is different from the eleventh to sixteenth embodiment in thatThe method comprises the following steps: step two2Ce (NO) in O solution3)3And K2PtCl4The molar ratio is 10: 1. other steps and parameters are the same as in one of the eleventh to sixteenth embodiments.
The specific implementation mode is eighteen: this embodiment is different from one of the eleventh to seventeenth embodiments in that: ce (NO) in step two3)3Ce (NO) in aqueous solution3)3The molar concentration was 0.11M. Other steps and parameters are the same as those in one of the eleventh to seventeenth embodiments.
The detailed embodiment is nineteen: this embodiment is different from one of the eleventh to eighteenth embodiments in that: said K in step two-2PtCl4K in aqueous solution2PtCl4The molar concentration is 0.011M. Other steps and parameters are the same as those in one of the eleventh to eighteenth embodiments.
The specific implementation mode twenty: this embodiment is different from one of the eleventh to nineteenth embodiments in that: and step two, the concentration of graphite oxide in the graphene oxide turbid liquid is 5.5 mg/mL. Other steps and parameters are the same as those in one of the eleventh to nineteenth embodiments.
The specific implementation mode is twenty one: this embodiment is different from one of the eleventh to twenty embodiments in that: step two, Ce (NO) is reacted at room temperature3)3Aqueous solution and K2PtCl4The aqueous solution was added dropwise to 20ml of H at the same time2And (3) adding the solution O into the solution O at the dropping speed of 2 drops/s, changing the color of the aqueous solution from colorless to black, and maintaining the reaction at room temperature for 6 min. Other steps and parameters are the same as in one of the eleventh to twenty embodiments.
Specific embodiment twenty-two: this embodiment is different from the eleventh to twenty-one embodiment in that: secondly, adding the graphene oxide suspension into the first step, continuously stirring for 58min at 70 ℃, wherein the magnetic stirring speed is 45r/min, thus obtaining the reduced graphene oxide suspension loaded with cerium dioxide @ platinum alloy nano particles, and marking as RGO-CeO2@ Pt suspension. Other steps and parameters and embodiments eleven to twentyOne of them is the same.
Specific embodiment twenty-three: this embodiment is different from one of the eleventh to twenty-second embodiments in that: secondly, excessive ethyl ether is used for extraction, and Keggin type phosphomolybdotungstic heteropoly acid which is marked as PMo is obtained6W6And (3) solution. Other steps and parameters are the same as those in one of the eleventh to twenty-second embodiments.
Twenty-four specific embodiments: this embodiment is different from one of the eleventh to twenty-third embodiments in that: the concentration of the polyethyleneimine aqueous solution in the third step is 11 mM. Other steps and parameters are the same as those in one of the eleventh to twenty-third embodiments.
The specific implementation mode is twenty five: this embodiment is different from one of the eleventh to twenty-fourth embodiments in that: immersing the GCE electrode in the polyethyleneimine water solution for 24 hours, taking out, washing with deionized water, and then using N2And drying by blowing to obtain the polyethylene imine layer. Other steps and parameters are the same as in one of the eleventh to twenty-fourth embodiments.
The specific implementation mode is twenty-six: this embodiment differs from the eleventh to twenty-fifth embodiment in that: step III, immersing the PMo obtained in the step I6W6Soaking in the solution for 20min, taking out, washing with deionized water, and adding N2And drying to obtain the phosphomolybdic tungsten heteropoly acid layer. Other steps and parameters are the same as the embodiments in one of eleventh to twenty-fifth.
The specific implementation mode is twenty-seven: this embodiment differs from the eleventh to twenty-sixth embodiment in that: step three, immersing the RGO-CeO obtained in the step two2Soaking in @ Pt suspension for 20min, taking out, washing with deionized water, and adding N2And drying the graphene to obtain the reduced graphene oxide layer loaded with the cerium dioxide @ platinum alloy nanoparticles. Other steps and parameters are the same as those in the first to the second embodiments.
Twenty-eighth specific embodiment the difference between the eleventh to twenty-seventh specific embodiments is that the third step, the fourth step, the operation of the third step, the fourth step, ~6 times, the heteropoly acid/graphene/CeO is obtained2Working electrode for electrochemical sensors of @ Pt, noted PEI/(PMo)6W6/RGO-CeO2@Pt)6Modified GCE electrodes. Other steps and parameters are the same as those in the eleventh to twenty-seventh embodiments.
The following experiments were conducted to verify the effects of the present invention
Test one, the preparation method of the working electrode for the heteropolyacid-based electrochemical sensor of this test was carried out according to the following steps:
firstly, preparing a Keggin type phosphomolybdic tungsten heteropoly acid solution: combining Na2WO4·2H2O、Na2MoO4·2H2O and NaH2PO4·2H2O is dispersed into 67mL of distilled water, and the reaction is maintained for 2.5h at 82 ℃; ② 34mL of hydrochloric acid solution with the mass fraction of 23 percent is added into the (I), and the color of the solution turns to bright yellow. Extracting with excessive ether to obtain Keggin type phosphomolybdotungstic heteropoly acid marked as PMo6W6A solution;
in the first step2WO4·2H2O、Na2MoO4·2H2O and NaH2PO4·2H2The molar ratio of O is 2: 2: 1;
in the first step2WO4·2H2The molar concentration of O is 0.65M;
in the first step2MoO4·2H2The molar concentration of O is 0.65M;
the NaH in the first step2PO4·2H2The molar concentration of O is 0.325M;
secondly, preparing a reduced graphene oxide suspension loaded with cerium dioxide @ platinum alloy nanoparticles: adding Ce (NO) at room temperature3)3Aqueous solution and K2PtCl4The aqueous solution was added dropwise to 20ml of H at the same time2In the O solution, the dropping speed is 2 drops/s, the color of the aqueous solution is changed from colorless to black, and the reaction is maintained for 6min at room temperature; ② adding the suspension added with the graphene oxide to the first step, and keeping the suspension at 70 DEG CStirring for 58min, wherein the magnetic stirring speed is 45r/min, thus obtaining the reduced graphene oxide suspension loaded with the cerium dioxide @ platinum alloy nano particles, marked as RGO-CeO2@ Pt suspension;
step two2Ce (NO) in O solution3)3And K2PtCl4The molar ratio is 10: 1;
ce (NO) in step two3)3Ce (NO) in aqueous solution3)3The molar concentration is 0.11M;
said K in step two-2PtCl4K in aqueous solution2PtCl4The molar concentration is 0.011M;
secondly, the concentration of graphite oxide in the graphene oxide turbid liquid is 5.5 mg/mL;
thirdly, based on heteropoly acid/graphene/CeO2Preparation of working electrode for electrochemical sensor of @ Pt: firstly, immersing a GCE electrode in a polyethyleneimine aqueous solution for 24 hours, taking out, washing with deionized water, and then washing with N2Drying to obtain a polyethyleneimine layer; ② immersing in the PMo obtained in the step one6W6Soaking in the solution for 20min, taking out, washing with deionized water, and adding N2Drying to obtain a phosphorus-molybdenum-tungsten heteropoly acid layer; ③ immersing in the RGO-CeO obtained in the second step2Soaking in @ Pt suspension for 20min, taking out, washing with deionized water, and adding N2Drying to obtain reduced graphene oxide layer loaded with cerium dioxide @ platinum alloy nanoparticles, and repeating the operation of the step ~ for 6 times to obtain the product based on heteropoly acid/graphene/CeO2Working electrode for electrochemical sensors of @ Pt, noted PEI/(PMo)6W6/RGO-CeO2@Pt)nModified GCE electrodes.
(one) for PEI/(PMo) on GCE electrode obtained in experiment one6W6/RGO-CeO2@Pt)6And (5) modifying the film for morphology characterization.
The PEI/(PMo) obtained in the first experiment was examined by a Scanning Electron Microscope (SEM) of the S-4300 type6W6/RGO-CeO2@Pt)6Modifying the film for morphology and junctionTexture characterization, resulting in PEI/(PMo) on GCE electrode obtained as test one shown in FIG. 16W6/RGO-CeO2@Pt)6Scanning electron microscope image of ceria @ platinum alloy nanoparticles in modified film, PEI/(PMo) on GCE electrode obtained in experiment I shown in FIG. 26W6/RGO-CeO2@Pt)6Scanning electron microscope image of reduced graphene oxide loaded with ceria @ platinum alloy nanoparticles in modified film, PEI/(PMo) on GCE electrode obtained in the first experiment shown in fig. 36W6/RGO-CeO2@Pt)6Scanning electron microscopy of the modified film.
As can be seen from FIG. 1, CeO2The @ Pt alloy nanoparticles were spherical particles with an average particle size of 48 nm. From FIG. 2, CeO can be seen2The @ Pt alloy nano particles are distributed on the graphene nano sheet more uniformly. From FIG. 3, PMo can be seen6W6With RGO-CeO2@ Pt is tightly held together and has an average particle size of about 18 nm.
(II) performing the PEI/(PMo) on the electrode obtained in the first test by using an X-ray photoelectron spectrometer6W6/RGO-CeO2@Pt)6The membranes were modified for characterization to give PEI/(PMo) on GCE electrode as shown in FIG. 46W6/RGO-CeO2@Pt)6The full spectrum of the X-ray photoelectron spectrum of the modified film in the range of 0 ~ 960 eV, from the XPS chart, it can be seen that PMo6W6、RGO、CeO2And Pt were both successfully deposited on the modified film.
(III) verification of PEI/(PMo) obtained in the first test of the application6W6/RGO-CeO2@Pt)6Sensing performance of the modified GCE electrode.
Preparation of electrochemical sensor
PEI/(PMo) obtained by the test one of the present application6W6/RGO-CeO2@Pt)6The modified GCE electrode is used as a working electrode, the Ag/AgCl electrode is used as a reference electrode, the platinum wire electrode is used as an auxiliary electrode, and the formed three-electrode system is the electrochemical sensor.
Secondly, the electrochemical sensor obtained in the step one is used for simultaneously detecting xanthine and uric acid
And (4) conclusion: obtaining a cyclic voltammogram of the electrochemical sensor shown in fig. 5 for catalyzing xanthine and uric acid in 0.1M PBS (pH =6), a graph of response current versus added xanthine concentration shown in fig. 6, and a graph of response current versus added uric acid concentration shown in fig. 7; wherein 1 represents the cyclic voltammogram to which xanthine and uric acid with a concentration of 0 μ M are added, 2 represents the cyclic voltammogram to which xanthine and uric acid with a concentration of 10 μ M are added, 3 represents the cyclic voltammogram to which xanthine and uric acid with a concentration of 20 μ M are added, 4 represents the cyclic voltammogram to which xanthine and uric acid with a concentration of 30 μ M are added, and 5 represents the cyclic voltammogram to which xanthine and uric acid with a concentration of 40 μ M are added, respectively, as can be seen from FIG. 5, two irreversible oxidation peaks appear at 0.46V and 0.89V after xanthine and uric acid are added, wherein 0.46V is the catalytic potential of uric acid, 0.89V is the catalytic potential of xanthine, and the catalytic peak current values of the corresponding catalytic potentials uniformly increase with the increasing concentrations of xanthine and uric acid. This is PEI/(PMo)6W6/RGO-CeO2@Pt)6The modified membrane simultaneously carries out catalytic oxidation reaction on xanthine and uric acid to cause corresponding change of peak current. Thus, the combination of PEI/(PMo) is further illustrated6W6/RGO-CeO2@Pt)6The electrochemical sensor constructed on the basis of the modified membrane has good performance for simultaneously detecting xanthine and uric acid.
Therefore, a working electrode for a heteropolyacid-based electrochemical sensor was successfully produced, and an electrochemical sensor constructed on the basis of this working electrode had excellent sensing performance for xanthine and uric acid.
Claims (10)
1. The working electrode for the electrochemical sensor of the heteropoly acid group is characterized in that the working electrode for the electrochemical sensor of the heteropoly acid group is composed of a GCE electrode and PEI/(PMo) coated outside the GCE electrode6W6/RGO-CeO2@ Pt) n modified film, which is formed by sequentially coating PEI: polyethylene layer, PMo6W6: phosphomolybdotungstic heteropoly acid layer, RGO-CeO2@ Pt: reduced graphene oxide layer loaded with cerium dioxide @ platinum alloy nanoparticles and PMo6W6Layer and RGO-CeO2The @ Pt layer is a unit of one cycle, and is cycled n times.
2. A working electrode for a heteropolyacid based electrochemical sensor according to claim 1, wherein n =1 ~ 6.
3. The working electrode for a heteropolyacid based electrochemical sensor according to claim 1, wherein the PEI/(PMo) is6W6/RGO-CeO2@ Pt) n modified film was 0.33 μm ~ 1.46.46 μm thick.
4. The working electrode for the heteropolyacid base electrochemical sensor according to claim 1, wherein the heteropolyacid is a Keggin-type phosphomolybdotungstic heteropolyacid having a molecular formula of H3PMo6W6O40•mH2O, m =36 ~ 42, with an atomic ratio of P: Mo: W of 1: 6: 6.
5. The working electrode for a heteropolyacid group electrochemical sensor according to claim 1, wherein the polyethyleneimine layer is obtained by modification with a GCE electrode in a polyethyleneimine solution having a concentration of 9mmol/L ~ 13mmol/L, and the modification time is 15min ~ 20 min.
6. The working electrode for a heteropoly acid based electrochemical sensor as claimed in claim 1, wherein the phosphomolybdotungstic heteropoly acid layer in each cycle is obtained by modifying a phosphomolybdotungstic heteropoly acid solution with a concentration of 5mg/L ~ 8mg/L by GCE electrode for 15min ~ 20 min.
7. The working electrode for a heteropolyacid-based electrochemical sensor according to claim 1, wherein the reduced graphene oxide layer on which ceria @ platinum alloy nanoparticles are supported in each cycleIs RGO-CeO modified by GCE electrode at the concentration of 6mg/L ~ 10mg/L2The modification time was 15min ~ 20min, obtained in the @ Pt suspension.
8. The working electrode for a heteropolyacid based electrochemical sensor according to claim 1, wherein the RGO-CeO2The concentration ratio of the cerium dioxide to the platinum alloy nanoparticles in the @ Pt suspension is 0.1 ~ 0.11.11 mmol/L: 0.01 mmol/L.
9. The working electrode for a heteropoly acid based electrochemical sensor as claimed in claim 1, wherein the ceria @ platinum alloy nanoparticles in the reduced graphene oxide layer supporting the ceria @ platinum alloy nanoparticles in each cycle are spherical nanoparticles having a particle size of 18nm ~ 22 nm.
10. The working electrode for the heteropoly acid based electrochemical sensor, according to claim 1, wherein the reduced graphene oxide in the reduced graphene oxide layer loaded with ceria @ platinum alloy nanoparticles in each cycle is of a two-dimensional nanosheet structure and has a concentration of 5mg/mL ~ 6 mg/mL.
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