CN109187677B - Pt/g-C3N4Composite material, electrochemical sensor, preparation method and application thereof - Google Patents

Abstract

The inventor provides a Pt/g-C₃N₄The inventor combines Pt with g-C by a simple synthesis method₃N₄The composite material is formed and is used as an electrode substrate material to be applied to an electrochemical sensor, and the constructed electrochemical sensor can realize quick, sensitive and efficient electrochemical detection of phenol. Composite material Pt/g-C₃N₄Has the electrocatalytic activity of noble metal Pt, and is also due to g-C₃N₄Large specific surface area, so that Pt/g-C₃N₄The compound can improve the electron transfer capacity, Pt and g-C, in the phenol oxidation process₃N₄The synergistic effect of the two components enables the electrochemical signal to obviously enhance the detection sensitivity of phenol. At the same time, Pt/g-C₃N₄The electrochemical sensor has no obvious response current to interferents such as ethanol, glycol, toluene, acetic acid, acetone and the like, and has good selectivity.

Description

Pt/g-C3N4Composite material, electrochemical sensor, preparation method and application thereof

Technical Field

The invention relates to the field of electrochemistry, in particular to Pt/g-C₃N₄A composite material,An electrochemical sensor, a preparation method and application thereof.

Background

In recent years, nanotechnology has been rapidly developed, wherein noble metal nanomaterials not only have general characteristics of nanomaterials (small size effect, macroscopic quantum size effect, surface effect), but also have specific catalytic activity and photoelectric characteristics which can be adjusted according to actual needs, and electromagnetic characteristics make them ideal materials for multiplex analysis and detection. Carbon nitride (g-C)₃N₄) Is a stable metal-free semiconductor material, and has the advantages of low cost, simple synthesis, good catalytic performance, good biocompatibility, large specific surface area and the like, in recent years, the g-C₃N₄The method also has wide application in the fields of biosensors, pollutant degradation in water, carbon dioxide reduction and the like.

Phenol, a toxic pollutant, can enter the human body through various ways such as respiratory tract, skin and oral cavity, and chemically react with cell protoplasm protein in the human body to stimulate the nerve center system, thereby causing serious harm to the human health. Phenol has been classified as one of the priority pollutants by the Environmental Protection Agency (EPA). Therefore, the development of a sensitive, rapid and economical method for quantitatively analyzing phenol is not always slow. The traditional detection methods comprise a high performance liquid chromatography, a capillary electrophoresis method, a chemiluminescence method and the like, but the methods usually take time and labor, are complex to operate, are expensive in instruments and are difficult to realize real-time field detection. The electrochemical method has the advantages of high sensitivity, good stability, simple and convenient operation, low cost, easy realization of on-site detection and the like. Therefore, the development of phenol electrochemical sensors has been a hot spot of research. However, unmodified carbon paper has little electrochemical response to phenol. Therefore, the search for suitable materials to modify the carbon paper becomes the key for constructing the high-sensitivity phenol electrochemical sensor.

Disclosure of Invention

Therefore, the invention provides Pt/g-C₃N₄Composite material of said Pt/g-C₃N₄The composite material is chloroplatinic acid and g-C₃N₄Is prepared by a precipitation reduction method.

The inventor also provides a Pt/g-C₃N₄The preparation method of the composite material is characterized by comprising the following steps:

g-C₃N₄preparing a suspension: mixing g-C with particle diameter of 1-10 μm₃N₄Adding the powder into deionized water, and performing ultrasonic treatment for 25-35min to obtain g-C₃N₄Suspending liquid;

Pt/g-C₃N₄preparing a suspension: g-C within 10-15 minutes₃N₄Slowly adding a chloroplatinic acid solution into the suspension, and continuing to perform ultrasonic treatment for 3-8min after adding the chloroplatinic acid solution to obtain a first suspension;

adding a sodium citrate solution into the first suspension, and carrying out ultrasonic treatment for 15-20min to obtain a second suspension; the sodium citrate can ensure that Pt nano particles generated by subsequent reaction are dispersed more uniformly;

adding the second suspension into sodium borohydride solution within 3s, and continuously stirring for 30-50min to obtain the solution containing Pt/g-C₃N₄The third suspension of (4);

separation and drying: performing solid-liquid separation on the third suspension, washing the precipitate with deionized water and ethanol, and drying to obtain Pt/g-C₃N₄Powder;

the g to C₃N₄The preparation method is a high-temperature calcination preparation method of melamine,

the chloroplatinic acid solution, the sodium citrate solution and the sodium borohydride solution are prepared by deionized water. The deionized water is used for configuration, so that interference impurities can be effectively prevented from being introduced in the preparation of the electrode.

Further, the g-C₃N₄The molar ratio of the chloroplatinic acid to the sodium borohydride is 200-800: 1-5-200-800;

further, the sodium citrate is mixed with g-C₃N₄The molar ratio of (A) to (B) is 1-4: 3-7.

The inventors also provide Pt/g-C₃N₄Use of a composite material in the manufacture of an electrochemical sensor.

Further, use of the electrochemical sensor to detect phenol.

The inventors also provide an electrochemical sensor employing the above Pt/g-C₃N₄The composite material is used as an electrode substrate material.

Further, the preparation method of the electrochemical sensor electrode comprises the following steps:

preparing a working solution: mixing Pt/g-C₃N₄Putting the powder into N, N-dimethylformamide, and carrying out ultrasonic treatment for more than 60min to obtain uniformly dispersed working solution;

preparing a working electrode: and uniformly dripping the working solution on the load electrode, and naturally drying at 20-30 ℃ to obtain the working electrode.

Further, the load electrode is bare carbon paper.

The inventors provide the use of the electrochemical sensor for detecting phenol.

Different from the prior art, the Pt/g-C provided by the technical scheme₃N₄Composite material and point chemical sensor, combining Pt with g-C by a simple synthesis method₃N₄The formed composite material is used as an electrode substrate material to be applied to an electrochemical sensor, and the constructed electrochemical sensor can realize quick, sensitive and efficient electrochemical detection of phenol. Composite material Pt/g-C₃N₄Has good electrocatalytic activity of noble metal nano-grade, and is due to g-C₃N₄Large specific surface area, so that Pt/g-C₃N₄The compound can improve the electron transfer capacity, Pt and g-C, in the phenol oxidation process₃N₄The synergistic effect of the two components enables the electrochemical signal to obviously enhance the detection sensitivity of phenol. At the same time, Pt/g-C₃N₄The electrochemical sensor has no obvious response current to interferents such as ethanol, glycol, toluene, acetic acid, acetone and the like, and has good selectivity.

Drawings

FIG. 1 shows Pt/g-C₃N₄A Scanning Transmission Electron Microscope (STEM) map of (a);

FIG. 2 shows Pt/g-C₃N₄X-ray diffraction (XRD) pattern of (a);

FIG. 3 shows bare CP (a), g-C₃N₄/CP(b),Pt/g-C₃N₄(c) cyclic voltammogram of 50 μ M phenol in 0.1M PBS (pH 3.0) with a scan rate of 0.05 Vs-1;

FIG. 4 shows Pt/g-C in 0.1M PBS containing 50. mu.M phenol at various pH's (1.0-4.0)₃N₄CV diagram of/CP, the insets show the response current and pH relationship;

FIG. 5 shows Pt/g-C₃N₄A linear plot of the oxidation peak potential of/CP phenol versus pH;

FIG. 6 shows Pt/g-C₃N₄Cyclic voltammograms of/CP in 0.1M PBS, 50. mu.M phenol solution at different scan rates (0.03-0.12 Vs-1);

FIG. 7 is Pt/g-C₃N₄A linear plot of/CP peak current versus the square root of scan rate;

FIG. 8 shows Pt/g-C₃N₄Cyclic voltammograms (from 2 μ M to 20 μ M) of/CP on different concentrations of phenol in 0.1M PBS (pH 3.0);

FIG. 9 shows Pt/g-C₃N₄Linear relationship of/CP peak current and concentration;

FIG. 10 shows the continuous addition of phenol at a concentration of Pt/g-C to a 0.1M PBS (pH 3.0)₃N₄The chronoamperometric response of the/CP electrode, and the inset is a calibration curve of the response current and the concentration;

FIG. 11 shows the addition of different substances to a buffer solution (pH 3.0) corresponding to Pt/g-C₃N₄Ampere response plot of/CP electrode.

Detailed Description

To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.

Example 1Pt/g-C₃N₄Powder preparation

1. Preparation of carbon nitride

4g of melamine is put into a mortar for grinding and then is put into a crucible, and the crucible is moved into a muffle furnace after a certain gap is reserved between the crucible and a cover. The temperature in the furnace was kept at 520 ℃ at a rate of 5 ℃/min, and the calcination was carried out for 4 hours. And naturally cooling to room temperature after the calcination is finished to obtain light yellow carbon nitride powder.

2.Pt/g-C₃N₄Synthesis and powder preparation of

Taking 50mg of carbon nitride (g-C) prepared with the granularity of 1-10 mu m₃N₄) The powder was dissolved in 40m L of deionized water, sonicated for 30min, then 0.3m L of chloroplatinic acid H was added over 15min₂PtCl₆·6H₂Slowly dripping O (0.01M) into the carbon nitride suspension, and continuing to perform ultrasonic treatment for 5min to obtain a mixed suspension;

0.0645g of anhydrous sodium citrate C₆H₅Na₃O₇Dissolving in 5m L deionized water, adding dropwise into the above mixed suspension, subjecting the suspension to ultrasonic treatment for 20min, mixing, and adding fresh NaBH in 3s₄(0.05M) solution 10M L, continuously and fully stirring for reaction for 40min, centrifuging by using a high-speed centrifuge after the reaction is finished, removing supernate, collecting precipitate, washing the precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a constant-temperature drying box at 60 ℃ for 10h to obtain Pt/g-C₃N₄And (3) powder.

Example 2

1. Preparation of carbon nitride

4g of melamine is put into a mortar for grinding and then is put into a crucible, and the crucible is moved into a muffle furnace after a certain gap is reserved between the crucible and a cover. The temperature in the furnace was kept at 520 ℃ at a rate of 5 ℃/min, and the calcination was carried out for 4 hours. And naturally cooling to room temperature after the calcination is finished to obtain light yellow carbon nitride powder.

2.Pt/g-C₃N₄Synthesis and powder preparation of

Taking 0.2mol of carbon nitride (g-C) prepared with the granularity of 1-10 mu m₃N₄) The powder was dissolved in 50m L of deionized water, sonicated for 25min, and then 0.5m L of chloroplatinic acid solution (1mmol H) was added at 12min₂PtC_l6·6H₂O configuration₎Slowly dripping the mixture into the carbon nitride suspension, and continuing to perform ultrasonic treatment for 8min to obtain a mixed suspension;

0.2mol of anhydrous sodium citrateC₆H₅Na₃O₇Dissolving in 10m L deionized water, adding dropwise into the above mixed suspension, subjecting the suspension to ultrasonic treatment for 20min, mixing, and adding fresh 0.2mol NaBH in 3s₄Continuously and fully stirring the solution 10m L for reaction for 30min, centrifuging by using a high-speed centrifuge after the reaction is finished, discarding the supernatant, collecting the precipitate, washing the precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a constant-temperature drying oven at 55 ℃ for 12h to obtain Pt/g-C₃N₄And (3) powder.

Example 3

1. Preparation of carbon nitride

4g of melamine is put into a mortar for grinding and then is put into a crucible, and the crucible is moved into a muffle furnace after a certain gap is reserved between the crucible and a cover. The temperature in the furnace was kept at 520 ℃ at a rate of 5 ℃/min, and the calcination was carried out for 4 hours. And naturally cooling to room temperature after the calcination is finished to obtain light yellow carbon nitride powder.

2.Pt/g-C₃N₄Synthesis and powder preparation of

Taking 0.8mol of carbon nitride (g-C) prepared with the granularity of 1-10 mu m₃N₄) The powder was dissolved in 100m L of deionized water, sonicated for 35min, and then 1m L of a solution of chloroplatinic acid (5mmol H) was added over 10-15min₂PtC_l6·6H₂O configuration) is slowly dripped into the carbon nitride suspension, and the time is continuously exceeded for 8min to obtain mixed suspension; 0.5mol of anhydrous sodium citrate C₆H5Na₃O₇Dissolving in 10m L deionized water, adding dropwise into the above mixed suspension, ultrasonically treating the suspension for 20min, mixing, and adding newly prepared 0.8mol NaBH in 3s₄Continuously and fully stirring the prepared solution of 15m L for reaction for 50min, centrifuging the solution by using a high-speed centrifuge after the reaction is finished, discarding supernatant, collecting precipitate, washing the precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying the precipitate in a constant-temperature drying oven at 60 ℃ for 10h to obtain Pt/g-C₃N₄And (3) powder.

Example 4

1. Preparation of carbon nitride

4g of melamine is put into a mortar for grinding and then is put into a crucible, and the crucible is moved into a muffle furnace after a certain gap is reserved between the crucible and a cover. The temperature in the furnace was kept at 520 ℃ at a rate of 5 ℃/min, and the calcination was carried out for 4 hours. And naturally cooling to room temperature after the calcination is finished to obtain light yellow carbon nitride powder.

2.Pt/g-C₃N₄Synthesis and powder preparation of

Taking 0.7mol of carbon nitride (g-C) prepared with the granularity of 1-10 mu m₃N₄) The powder was dissolved in 100m L of deionized water, sonicated for 35min, then 1m L of chloroplatinic acid solution (3mmol H) was added for 10-15min₂PtC_l6·6H₂O configuration) is slowly dripped into the carbon nitride suspension, and the time is continuously exceeded for 8min to obtain mixed suspension; 0.4mol of anhydrous sodium citrate C₆H₅Na₃O₇Dissolving in 10m L deionized water, adding dropwise into the above mixed suspension, ultrasonically treating the suspension for 20min, mixing, and adding newly prepared 0.6mol NaBH in 3s₄Continuously and fully stirring the prepared solution of 15m L m for reaction for 40min, centrifuging the solution by using a high-speed centrifuge after the reaction is finished, discarding supernatant, collecting precipitate, washing the precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying the precipitate in a constant-temperature drying box at 60 ℃ for 10h to obtain Pt/g-C₃N₄And (3) powder.

Example 5

1. Preparation of carbon nitride

4g of melamine is put into a mortar for grinding and then is put into a crucible, and the crucible is moved into a muffle furnace after a certain gap is reserved between the crucible and a cover. The temperature in the furnace was kept at 520 ℃ at a rate of 5 ℃/min, and the calcination was carried out for 4 hours. And naturally cooling to room temperature after the calcination is finished to obtain light yellow carbon nitride powder.

2.Pt/g-C₃N₄Synthesis and powder preparation of

Taking 0.3mol of carbon nitride (g-C) prepared with the granularity of 1-10 mu m₃N₄) The powder was dissolved in 100m L of deionized water, sonicated for 35min, then 1m L of chloroplatinic acid solution (2mmol H) was added for 10-15min₂PtCl₆·6H₂O configuration) is slowly dripped into the carbon nitride suspension, and the time is continuously exceeded for 8min to obtain mixed suspension; 0.1mol of anhydrous sodium citrate C₆H₅Na₃O₇Dissolving in 10m L deionized water, adding dropwise into the above mixed suspension, ultrasonically treating the suspension for 20min, mixing, and adding newly prepared 0.8mol NaBH in 3s₄Continuously and fully stirring the prepared solution of 15m L for reaction for 30min, centrifuging the solution by using a high-speed centrifuge after the reaction is finished, discarding supernatant, collecting precipitate, washing the precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying the precipitate in a constant-temperature drying oven at 65 ℃ for 10h to obtain Pt/g-C₃N₄And (3) powder.

Pt/g-C₃N₄(preparation of example 1) performance testing:

1. analysis of Pt/g-C₃N₄Morphological characteristics of the composite:

Pt/g-C prepared in example 1₃N₄Complexes, analysis of Pt/g-C by Scanning Transmission Electron Microscopy (STEM)₃N₄The morphology of the composite is shown in detail in FIG. 1.

From the left graph, it can be seen that₃N₄The surface of (2) is dispersed with fine Pt nano particles, which shows that Pt is successfully attached to g-C₃N₄The above. Furthermore, the different colors on the right panel represent different elements, which shows that the nanocomposite only contains three elements of C, N and Pt, thus demonstrating that Pt and g-C can be derived₃N₄Coexisting and Pt well distributed in g-C₃N₄On the surface, the above shows that the synthesis of Pt/g-C with higher purity is successful₃N₄A composite material. Pt/g-C₃N₄The composite material is g-C₃N₄The composite structure is an inner core, and Pt is an outer layer.

2. For Pt/g-C₃N₄XRD analysis of the composite:

Pt/g-C prepared in example 1₃N₄The complex was subjected to X-ray diffraction, and the diffraction pattern thereof is shown in FIG. 2.

The spectrum of fig. 2 shows a strong diffraction peak at 27.73 ° 2 θ, which corresponds to g-C₃N₄The diffraction peak at 2 θ of 12.98 ° corresponds to g-C₃N₄The (100) crystal plane of (A); this is achieved byIn addition, in the XRD spectrogram, weak diffraction peaks appear at 17.89 ° 2 θ, 21.76 ° 2 θ and 57.04 ° 2 θ in succession, which is attributed to the formation of g-C in melamine under high temperature conditions₃N₄The corresponding intermediates are produced in the process of (1). Two additional diffraction peaks corresponding to the (111) and (200) crystal planes of the Pt nanoparticles at 39.54 ° 2 θ and 44.5 ° 2 θ, respectively.

This result again demonstrates Pt and g-C₃N₄Composite materials have been successfully synthesized.

Example 6 preparation of working electrodes and electric Sensors

Preparing a working solution: 5mg of Pt/g-C prepared in example 1 were weighed out₃N₄Dispersing the powder in 1m L N, N-Dimethylformamide (DMF), and performing ultrasonic treatment for 1h to obtain uniformly dispersed suspension, preparing working electrode by removing 5 μ L of the mixture and applying the mixture to carbon paper (0.3 × 0.5 cm)²) And naturally drying at room temperature, and preparing a working electrode by using the same.

2. Preparing an electric sensor:

the electric sensor is a three-electrode system. Wherein the carbon paper is loaded with Pt and g-C₃N₄The composite material is a working electrode, the silver/silver chloride electrode is a reference electrode, and the platinum electrode is a counter electrode. The electrodes are connected to an electrochemical workstation.

Pt/g-C₃N₄Electrochemical testing of the electrode:

in the experimental system, electrochemical experiments are carried out under a standard three-electrode system. Mixing Pt/g-C₃N₄Immersing a working electrode of the/CP in a phenol solution, testing the performance of the sensor by adopting a Cyclic Voltammetry (CV), and setting experimental parameters as follows; the scanning voltage is 0.7-1.2V, the scanning speed is 0.05Vs-1, and the standing time is 2 s. The fixed voltage for the ampere response is set to +0.95V, with a sampling interval of 0.02 s.

And (3) performance testing:

1. for CP, g-C₃N₄(ii) Pt/g-C and/CP₃N₄Performance test of electrical sensor with/C as electrode

Respectively with CP, g-C₃N₄(ii) Pt/g-C and/CP₃N₄the/CP electrode was a working electrode placed in a 0.1M PBS (pH 3.0) solution containing 50 μ M phenol, with a sweep voltage from 0.7 to 1.2V and a sweep rate of 0.05 Vs-1.

The results are shown in fig. 3, and curve (a) in fig. 3 is a CV graph of unmodified CP, with a very weak current response, indicating that bare CP is almost electrochemically inactive. Curve (b) represents g-C₃N₄The oxidation peak current of the/CP electrode is significantly higher than that of the unmodified CP, which indicates that g-C₃N₄Has catalytic activity. Curve (C) is Pt/g-C₃N₄CV diagram of/CP electrode.

By comparing three different modified electrodes, it can be seen that: when Pt nanoparticles are combined with g-C₃N₄When the CP electrode is modified together, Pt/g-C₃N₄The oxidation peak current of the/CP electrode is compared with that of CP and g-C₃N₄the/CP is significantly increased due to the good conductivity and g-C of Pt nanoparticles₃N₄Large specific surface area, so that Pt/g-C₃N₄The compound can improve the electron transfer capacity, Pt and g-C, in the phenol oxidation process₃N₄The synergistic effect of the two results in the obvious enhancement of electrochemical signals.

2. Different pH conditions for detecting Pt/g-C₃N₄Influence of the/C electrode

When the pH value is adjusted from 1 to 3, the current intensity of the oxidation peak is gradually increased, but the peak current of the oxidation peak is rather decreased as the pH is further increased, and therefore, pH 3.0 is the optimal pH value of the buffer. The electrochemical characteristics of the working electrode under different pH conditions were determined using cyclic voltammetry (CA), as shown in fig. 4.

FIG. 5 shows the relationship between oxidation peak potential and pH, with a linear equation: epa (V) ═ 0.04838V/pH +1.10015 (R) ═ 0.9996), the potential of the oxidation peak shifted negatively with increasing pH.

The above proves that: Pt/g-C₃N₄The pH of the/C electrode buffer is 3.0.

3、Pt/g-C₃N₄Different scanning rates of/CP electrodesInfluence on the current response:

the test results are shown in FIG. 6: different scan rates (0.03-0.12 Vs) in 0.1M PBS, 50. mu.M phenol solution^-1) Cyclic voltammograms below.

Fig. 7 is a linear plot of peak current versus the square root of scan rate. From FIG. 7, it can be seen that the total weight of the particles is 0.03-0.12Vs^-1In the range of (1), Pt/g-C₃N₄The oxidation peak current (Ipa) of the/CP modified electrode is linear with the square root of the scan rate (v1/2), and the anodic peak current gradually increases with increasing scan rate.

Linear regression equation: ipa (μ a) ═ 52.539v1/2(Vs-1)1/2-3.7975(R ═ 0.9953). The results show that phenol is present at Pt/g-C₃N₄The oxidation behavior on the/CP sensing surface is a diffusion-controlled process.

The graph in fig. 7 shows the relationship between the peak potential and lnv, the potential at the anode peak (Epa) is also moving towards the positive electrode in steps as the scan rate is increased, the linear relationship between epa (v) ═ 0.024881lnv (Vs-1) +0.99998(R ═ 0.9948), the results further illustrate that the electrocatalytic oxidation of phenol is kinetically controlled, the number of electrons transferred during oxidation can be calculated from this linear relationship and L aviron's equation, the L aviron's equation is as follows:

Epa＝E0–[RT/(1-α)nF]ln[RTKs/(1-α)nF]+[RT/(1-α)nF]lnv

where E0 is the standard redox potential, Ks is the standard rate coefficient, F is the Faraday constant, T is the Kelvin temperature, α is the transfer coefficient, n is the number of electrons transferred, from the slope of the peak potential (Epa) versus lnv, (1- α) n is calculated to be equal to 1.032, α can be calculated from the equation Ep/2-Ep-1.875 (RT/α F), Ep/2 represents the half-spike potential, from which α is calculated to be equal to 0.5250, and the number of electrons transferred is about 2.

It was confirmed that Pt/g-C₃N₄the/CP electrode has good electrocatalysis effect on the phenol oxidation process, and can be used for detecting phenol.

4、Pt/g-C₃N₄The electrochemical analysis performance of phenol is detected by the/CP electrode.

At a scan rate of 0.05Vs^-1In the case of (2), as the concentration of phenol was increased from 2 μ M to 20 μ M, the response current gradually increased, and as a result, as shown in fig. 8, it was observed from fig. 8 that the maximum peak current occurred at +0.95V, indicating that the sensor had a good electrocatalytic effect on the phenol oxidation process.

Fig. 9 shows a linear relationship between peak current and concentration, and the linear equation can be expressed as: ipa (μ a) ═ 1.21084C (μ M) -0.97465 (R ═ 0.9923), the sensitivity of the sensor was 1.21084mA μ M-1, and the lowest detection limit concentration was 0.667 μ M (S/N ═ 3).

It was confirmed that Pt/g-C₃N₄the/CP electrode has good electrocatalysis effect on the phenol oxidation process, and can be used for detecting phenol.

5. Pt/g-C at low concentrations under optimal experimental conditions₃N₄the/CP sensor detects phenol.

In the case where the detection voltage was set to +0.95V, Pt/g-C was set₃N₄the/CP electrode was placed in 100M L0.1M PBS (pH 3.0), and phenol, Pt/g-C, was added dropwise to the constantly stirred buffer solution at 40s intervals₃N₄the/CP electrode can respond quickly, the current can sharply increase in a short time and quickly reach a stable state.

The detection results are shown in FIG. 10, Pt/g-C₃N₄The ampere response curve of the/CP electrode; the inset shows a linear relationship between response current and phenol concentration, the linear equation being as follows: i (μ a) ═ 0.04276C (μ M) +0.1893(R ═ 0.9980), the linear range was 1 μ M to 10 μ M, the corresponding sensitivity was 0.04276 mA μ M-1, and the limit of detection was 0.333 μ M (S/N ═ 3).

It was confirmed that Pt/g-C₃N₄the/CP sensor has extremely high sensitivity to phenol detection.

6. And (3) detecting the anti-interference capability:

to study Pt/g-C₃N₄Selectivity of/CP electrode, adding some substances which may generate interference into the continuously stirred buffer solution during the experiment, and measuring Pt/g-C by amperometry₃N₄And modifying the anti-interference capability of the electrode. The interferents selected for this invention were ethanol, ethylene glycol, toluene, p-hydroxybenzaldehyde, acetic acid and acetone all at a concentration of 0.1M.

The results are shown in FIG. 11, from which it can be seen that the addition of ethanol, ethylene glycol, toluene, acetic acid and acetone did not cause a significant change in response current, indicating that Pt/g-C₃N₄The electrode has good selectivity. However, with the addition of p-hydroxybenzaldehyde, a current response immediately occurred. Therefore, interference of hydroxybenzaldehyde and the like with detection should be avoided in the detection of phenol.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal that comprises the element. Further, herein, "greater than," "less than," "more than," and the like are understood to exclude the present numbers; the terms "above", "below", "within" and the like are to be understood as including the number.

It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein, or by using equivalent structures or equivalent processes performed in the content of the present specification and the attached drawings, which are included in the scope of the present invention.

Claims (6)

1. Pt/g-C₃N₄The preparation method of the composite material is characterized by comprising the following steps:

g-C₃N₄preparing a suspension: mixing g-C with particle diameter of 1-10 μm₃N₄Adding the powder into deionized water, and performing ultrasonic treatment for 25-35min to obtain g-C₃N₄Suspending liquid;

Pt/g-C₃N₄preparing a suspension: g-C within 10-15 minutes₃N₄Slowly adding a chloroplatinic acid solution into the suspension, and continuing to perform ultrasonic treatment for 3-8min after adding the chloroplatinic acid solution to obtain a first suspension;

adding a sodium citrate solution into the first suspension, and carrying out ultrasonic treatment for 15-20min to obtain a second suspension;

adding the second suspension into sodium borohydride solution within 3s, and continuously stirring for 30-50min to obtain the solution containing Pt/g-C₃N₄The third suspension of (4);

separation and drying: performing solid-liquid separation on the third suspension, washing the precipitate with deionized water and ethanol, and drying to obtain Pt/g-C₃N₄Powder;

the g to C₃N₄The preparation method is a high-temperature calcination preparation method of melamine,

the chloroplatinic acid solution, the sodium citrate solution and the sodium borohydride solution are prepared by deionized water;

the Pt/g-C₃N₄The composite material is g-C₃N₄The composite structure is an inner core, and Pt is an outer layer; the Pt/g-C₃N₄The composite material is used for preparing an electrochemical sensor for detecting phenol.

2. The method of claim 1, wherein the g-C is₃N₄The mol ratio of the chloroplatinic acid to the sodium borohydride is 200-800:1-5: 200-800.

3. The method of claim 1The method is characterized in that the sodium citrate is mixed with g-C₃N₄The molar ratio of (A) to (B) is 1-4: 3-7.

4. An electrochemical sensor for detecting phenol, using the Pt/g-C prepared according to claim 1₃N₄The composite material is used as an electrode substrate material.

5. The electrochemical sensor according to claim 4, wherein the electrochemical sensor electrode is prepared by a method comprising the steps of:

preparing a working solution: mixing Pt/g-C₃N₄Putting the powder into N, N-dimethylformamide, and carrying out ultrasonic treatment for more than 60min to obtain uniformly dispersed working solution;

preparing a working electrode: and uniformly dripping the working solution on the load electrode, and naturally drying at 20-30 ℃ to obtain the working electrode.

6. The electrochemical sensor of claim 5, wherein the load electrode is bare carbon paper.

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