CN111468091A

CN111468091A - Preparation method and application of Pt-Au carbon-based in-situ reduction composite catalytic material

Info

Publication number: CN111468091A
Application number: CN202010281335.0A
Authority: CN
Inventors: 吴龙; 罗雅元; 侯梦雅; 李粤; 陈小强; 吴正奇
Original assignee: Hubei University of Technology
Current assignee: Hubei University of Technology
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2020-07-31
Anticipated expiration: 2040-04-10
Also published as: CN111468091B

Abstract

The invention provides a preparation method and application of a Pt-Au carbon-based in-situ reduction composite material. The method comprises the following steps: 1. preparing porous activated carbon; 2. synthesizing nanogold (AuNPs); 3. preparing a Pt-Au carbon-based composite material: weighing a certain amount of active carbonAdding distilled water into PE tube, mixing, adding PDDA, ultrasonic treating, centrifuging, collecting supernatant, adding nanogold into the precipitate, ultrasonic treating, standing, centrifuging, collecting supernatant, adding pure water into the precipitate, ultrasonic dispersing, and adding H₂PtCl₆After standing, NaBH is slowly added₄The pH was tested after the reaction and adjusted to pH 5-6. The composite material prepared by the invention can catalyze NaBH₄Methylene blue is reduced. And can also be used in the fields of industrial three-waste treatment, fuel cells, detection of pollutants in wastewater and the like. The method has the advantages of low cost, high efficiency, easy preparation, precipitation, separation and recovery and the like, and is beneficial to practical popularization and application.

Description

Preparation method and application of Pt-Au carbon-based in-situ reduction composite catalytic material

Technical Field

The invention belongs to the field of in-situ reduction nano composite catalytic materials, and particularly relates to a preparation method and application of a Pt-Au carbon-based catalytic composite material.

Background

China is a big tea-producing country, and since the innovation is opened, the tea planting area and the tea yield in China are the first world. With the development of society, many new business modes are continuously emerged. During the production, processing and consumption processes, a large amount of tea leaves are produced. It has been reported that the carbon content in tea leaves is very high and that there is a rich pore structure. If the waste tea leaves are reused, the environmental pressure can be reduced, and the tea resources can be fully utilized.

The active carbon is a black solid substance obtained by activating and carbonizing raw materials, mainly contains carbon and contains a small amount of elements such as oxygen, hydrogen, sulfur and the like. Currently, activated carbon has been widely used in various fields, for example, as an air purification material because of its advantages of good adsorption performance, fast adsorption speed, high adsorption amount, and the like. In the early stage, the preparation of the activated carbon in China mainly depends on wood, fruit shells and the like, but because the excessive use of the wood can cause irreversible influence on the environment and is not beneficial to the regeneration of petroleum, the development of a new raw material for preparing the activated carbon is a hotspot of current research.

The noble metal nanoparticles have great interest to researchers due to unique physicochemical properties, and the Au nanoparticles have the advantages of adjustable plasma characteristics and shape and size, excellent chemical stability and the like, and are widely applied. The Pt nano-particles are functional metals and are ideal catalysts for oxygen reduction reaction. The synthesized bimetallic nanoparticles can greatly expand the performance range of the metal nanoparticles. In recent years, attention has been paid to Pt-Au bimetallic materials, and the catalytic performance of Pt-Au bimetallic materials has been widely researched in the fields of optics and chemistry. Pt-Au has strong catalytic oxidation performance and electrocatalysis performance, and is widely used for catalyzing and degrading harmful substances and catalysts of fuel cells. It has also been reported that Pt-Au materials can be used to construct various analytical methods, such as electrochemical analysis and visual analysis.

Disclosure of Invention

Aiming at the problem of the source of the existing composite catalytic material, a preparation method and application of a Pt-Au carbon-based in-situ reduction composite catalytic material are provided. The method can successfully synthesize the Pt-Au carbon-based reduction composite catalytic material and has the performance of catalyzing and degrading methylene blue. The method also has the advantages of high efficiency, low cost, simplicity, convenience, easy implementation, resource waste reduction, recyclability and the like, and is favorable for practical popularization and application.

A preparation method of a Pt-Au carbon-based in-situ reduction composite material,

(1) preparing porous activated carbon;

(2) synthesizing nanogold (AuNPs);

(3) preparing a Pt-Au carbon-based composite material: weighing a certain amount of activated carbon, adding distilled water, fully mixing, adding PDDA, performing ultrasonic treatment, centrifuging, taking out supernatant, adding nanogold into precipitate, performing ultrasonic treatment, standing, centrifuging, taking out supernatant, adding pure water into precipitate, performing ultrasonic dispersion, and adding H₂PtCl₆After standing, NaBH is slowly added₄The pH was tested after the reaction and adjusted to pH 5-6.

The preparation method of the Pt-Au carbon-based in-situ reduction composite material comprises the following steps: drying wet tea leaves to obtain tea leaves after primary drying, weighing a certain amount of tea leaves, carrying out hydrothermal carbonization for 3-10h, naturally cooling, taking out a sample for drying, mixing potassium hydroxide and the sample according to a certain proportion, adding a small amount of deionized water for dissolving, adding absolute ethyl alcohol for drying, putting the dried sample into a tube furnace, rapidly heating to 500-700 ℃ under the protection of argon, keeping the temperature for 3-5h, cleaning the obtained sample with HCl, washing with deionized water to the pH value of 6-7, finally drying at the temperature of 60-105 ℃, and finally sealing for storage.

The preparation method of the Pt-Au carbon-based in-situ reduction composite material comprises the following steps: adding trisodium citrate into distilled water, and adding HAuCl₄Adding NaBH into ice water bath while stirring₄Until the color of the solution changes from orange red to wine red, and placing the solution in a conical flask for later use.

The preparation method of the Pt-Au carbon-based in-situ reduction composite material comprises the steps of drying wet tea residues at 60-105 ℃ for 15-24 hours to obtain primarily dried tea residues, weighing 2-6 g of tea residues, adding 40m L distilled water, uniformly mixing, putting into an autoclave, carrying out hydrothermal carbonization at 180-220 ℃ for 3-10 hours, naturally cooling, taking out a sample, drying at 60-105 ℃, mixing potassium hydroxide and the sample according to a certain proportion, adding a small amount of deionized water for dissolving, adding 2-5m L anhydrous ethanol, drying at 60-120 ℃ to obtain a dried sample, putting the dried sample into a tubular furnace, rapidly heating to 500-700 ℃ under the protection of argon gas, keeping the temperature for 3-5 hours, washing the obtained sample with HCl, washing with deionized water to the pH of 6-7, drying at 60-105 ℃, and finally sealing and storing.

The preparation method of the Pt-Au carbon-based in-situ reduction composite material comprises the steps of adding 0.005-0.01g of trisodium citrate into 100m L distilled water, and adding 1-1.5m L HAuCl₄Adding 2.5m L NaBH into ice water bath with stirring₄(0.1M) until the color of the solution changes from orange red to wine red, and placing the solution in an erlenmeyer flask for later use.

According to the preparation method of the Pt-Au carbon-based in-situ reduction composite material, the concentration of the PDDA is 10%.

The preparation method of the Pt-Au carbon-based in-situ reduction composite material comprises the step of preparing NaBH₄The preparation method comprises dissolving 0.0166g in 1m L ice water, and using as it is.

According to the preparation method of the Pt-Au carbon-based in-situ reduction composite material, the ratio of potassium hydroxide to a sample is 4: 1.

Pt-Au carbon-based in-situ reduction composite material for catalyzing NaBH₄Methylene blue is reduced.

Specifically, the invention is realized by the following technical scheme:

1. the preparation method of the Pt-Au carbon-based in-situ reduction composite material comprises the following reagents:

A. tea leaves

B. Potassium hydroxide (KOH)

C. Hydrochloric acid (HCl)

D. Diethylene glycol diacrylate Phthalate (PDDA)

E. Chloroauric acid (HAuCl)₄)

F. Trisodium citrate (Na)₃C₆H₅O₇·2H₂O)

G. Sodium borohydride (NaBH)₄)

H. Chloroplatinic acid (H)₂PtCl₆)

2. The method comprises the following steps:

(1) preparing porous activated carbon, namely drying wet tea residues at 60-105 ℃ for 15-24h to obtain primarily dried tea residues, weighing 2-6 g of tea residues, adding 40m L distilled water, uniformly mixing, putting into an autoclave, carrying out hydrothermal carbonization at 180 ℃ and 220 ℃ for 3-10h, naturally cooling, taking out a sample, drying at 60-105 ℃, mixing potassium hydroxide and the sample according to a certain proportion, adding a small amount of deionized water for dissolving, adding 2-5m L absolute ethyl alcohol, drying at 60-120 ℃ to obtain a dried sample, putting the dried sample into a tube furnace, rapidly heating to 500 ℃ and 700 ℃ under the protection of argon, keeping the temperature for 3-5h, cleaning the obtained sample by using HCl, then washing the sample to pH6-7 by using deionized water, finally drying at 60-105 ℃, and finally sealing for storage, wherein preferably, the ratio of potassium hydroxide to the sample is 4: 1.

(2) Synthesis of Nanogold (AuNPs) by adding 0.005-0.01g trisodium citrate to 100m L distilled water, and adding 1-1.5m L HAuCl₄Adding 2.5m L NaBH into ice water bath with stirring₄(0.1M) to the color of the solutionThe orange red turns into wine red and is placed in a conical flask for standby.

(3) Weighing 1-1.5mg of Activated Carbon (AC) in a PE tube, adding 5-10m L distilled water, fully mixing, adding 2-5m L10% PDDA, performing ultrasonic treatment for 10-15min, centrifuging (7000r, 5min), taking out supernatant, adding 15-25m L nanogold (AuNPs) into the precipitate, performing ultrasonic treatment for 1-5min, standing for 60-120min, centrifuging (7000r, 5min), taking out supernatant, adding 10-20m L pure water into the precipitate, performing ultrasonic treatment for 1-5min for dispersion, adding 200 ion 600u L H, dispersing for 1-5min₂PtCl₆Standing for 10-30min, and slowly adding 0.5-2m L NaBH₄(0.0166g in 1m L ice water, ready for use), after 60min of reaction, the pH was measured and adjusted to pH5-6 with dilute hydrochloric acid.

The invention has the beneficial effects that:

the invention provides a preparation method and application of a Pt-Au carbon-based in-situ reduction composite material. The composite material prepared by the invention can catalyze NaBH₄Methylene blue is reduced. And can also be used in the fields of industrial three-waste treatment, fuel cells, detection of pollutants in wastewater and the like. The method has the advantages of low cost, high efficiency, easy preparation, precipitation, separation and recovery and the like, and is beneficial to practical popularization and application.

Drawings

FIG. 1 is a scheme of the synthesis of AC-Pt-Au;

FIG. 2 is a Scanning Electron Microscope (SEM) image of various samples;

FIG. 3 is an isothermal adsorption curve for AC;

FIG. 4 is an aperture size distribution plot of AC;

FIG. 5 is a Fourier infrared spectrum of AC and AC-Pt-Au;

FIG. 6 is a color rendering of AC-Pt-Au catalyzed TMB;

FIG. 7 is a diagram of the real object of the AC-Pt-Au catalytic reduction MB;

FIG. 8 is a graph representing electrocatalytic activity.

In FIG. 2, (A) is an SEM photograph of tea-leaf activated carbon AC, (B) is an SEM photograph of the AC-Pt-Au-H composite material obtained in example 1, (C) is an SEM photograph of the AC-Pt-Au-J composite material obtained by stirring in example 2, (D) is an SEM photograph of the AC-Pt-Au-C composite material obtained by ultrasonic preparation in example 3, and in FIG. 7, A is 1m L MB (10mg/m L) +400u L H₂O physical control group, B MB +200u L NaBH₄+200u L AC-Pt-Au actual picture of catalytic reduction MB +200u L H₂A MB physical map of the O +200u L AC-Pt-Au catalytic reduction MB, D is MB +200u L NaBH₄+200uL H₂An MB physical map is subjected to AC-Pt-Au catalytic reduction of O; in FIG. 8, a is a graph representing the oxygen reduction electrocatalytic activity of a bare glassy carbon electrode, and b is a graph representing the oxygen reduction electrocatalytic activity of an AC-Pt-Au modified glassy carbon electrode.

Detailed Description

Example 1

(1) Weighing about 100g of wet tea leaves, and drying the wet tea leaves in a constant-temperature drying oven at 100 ℃ for 24h to obtain the tea leaves after primary drying.

(2) Weighing 4g of dried tea residue sample, adding 40m L of distilled water, uniformly mixing, putting into a high-pressure kettle, carrying out hydrothermal carbonization for 5h at 200 ℃, naturally cooling, taking out the sample, and drying by using a constant-temperature drying oven at 100 ℃.

(3) Weighing 4g of KOH and 1g of sample, adding a small amount of deionized water to dissolve, adding 5m of L anhydrous ethanol, fully mixing, and drying at 115 ℃.

(4) Putting 4g of the sample obtained in the last step into a corundum boat, putting the corundum boat in a tube furnace, introducing argon for 20min in advance, heating to 200 ℃ at the speed of 10 ℃/min and keeping the temperature for 1h, then heating to 700 ℃ from 200 ℃, keeping the temperature for 3h under the protection of argon, cooling to room temperature and taking out the sample, washing the sample by 3 mol/L HCl, then washing by deionized water until the pH value is 6-7, finally drying in a drying box at the temperature of 105 ℃ for 24h, and keeping the obtained sample in a brown bottle.

(5) Putting 1.3mg carbon material (AC) in PE tube, adding 5m L pure water, mixing well, adding 2m L10% PDDA, performing ultrasonic treatment for 15min, centrifuging (5000 + 7000r, 5min), and taking out supernatant.

(6) 0.0074g of trisodium citrate is added into 100m L distilled water, and 1.04m L HAuCl is added₄Adding 2.5m L NaBH into ice water bath with stirring₄(0.1M) until the color of the solution changes from orange red to wine red, and placing the solution in an erlenmeyer flask for later use.

(7) Adding 18m L nano gold (Au NPs) into the precipitate, carrying out ultrasonic treatment for 1min, standing for 60min, centrifuging (5000 7000r, 5min), and taking out the supernatant.

(8) Adding 4m L pure water into the precipitate, dispersing by ultrasonic for 1min, adding 300u L H₂PtCl₆Mixing, standing for 10min, and slowly adding 0.5m L NaBH₄(0.0166g in 1m L ice water, ready for use), after 60min of reaction, the pH was measured, adjusted to pH5-6 with dilute hydrochloric acid, and the sample was named AC-Pt-Au-H.

Example 2

(1) Weighing about 100g of wet tea leaves, and drying at 100 ℃ in a constant-temperature drying oven to obtain primarily dried tea leaves.

(2) Weighing 4g of dried tea leaves, adding 40m of L distilled water, uniformly mixing, putting into a high-pressure kettle, carrying out hydrothermal carbonization for 5h at 200 ℃, naturally cooling, taking out a sample, and drying at 100 ℃.

(3) Weighing 4g of KOH and 1g of sample, adding a small amount of deionized water to dissolve, adding 5m of L absolute ethyl alcohol, fully mixing, and drying at 100 ℃.

(4) Putting 4g of the sample obtained in the last step into a corundum boat, putting the corundum boat in a tube furnace, introducing argon for 20min in advance, heating to 200 ℃ at the speed of 10 ℃/min, keeping the temperature for 1h, heating to 700 ℃ from 200 ℃, keeping the temperature for 3h under the protection of argon, cooling to room temperature, taking out the sample, cleaning the sample by 3 mol/L HCl, washing by deionized water until the pH value is 6-7, and finally drying at 105 ℃, and storing the obtained sample in a brown bottle.

(5) 1mg of carbon material (AC) was put in a PE tube, 5m L10% PDDA was added, stirred for 15min and mixed uniformly, centrifuged (5000 once 7000r, 5min), and the supernatant was taken out.

(7) Adding 5m L nano gold (Au NPs) into the precipitate, stirring for 60min, centrifuging (5000 7000r, 5min), taking out the supernatant, and if the supernatant is colorless, continuing to repeat the above steps until the supernatant is pink.

(8) Adding 4m L distilled water into the precipitate, mixing, adding 600u L H₂PtCl₆Stirring for 10min, and slowly adding 1m L NaBH₄(0.0166g of the product is dissolved in 1m L ice water and is ready to use) After stirring for 60min, the pH was tested, adjusted to pH5-6 with dilute hydrochloric acid, and the sample was named AC-Pt-Au-J.

Example 3

(3) Weighing 4g of KOH and 1g of samples, adding a small amount of distilled water for dissolving, adding 5m of L absolute ethyl alcohol, fully mixing, and drying at 100 ℃.

(5) Putting 1mg carbon material (AC) in PE tube, adding 2m L pure water, mixing well, adding 2m L10% PDDA, performing ultrasonic treatment for 15min, centrifuging (5000 + 7000r, 5min), and taking out supernatant.

(7) Adding 15m L nano gold (Au NPs) into the precipitate, carrying out ultrasonic treatment for 10min, standing for 60min, centrifuging (5000 7000r, 5min), and taking out the supernatant.

(8) Adding 2m L distilled water into the precipitate, mixing, performing ultrasonic treatment for 5min, adding 300u L H₂PtCl₆Ultrasonic treatment for 10min, and slowly adding 0.5m L NaBH₄(0.0166g dissolved in 1m L ice water, ready for use), sonicated for 10min, allowed to stand for 60min, tested for pH, adjusted to pH5-6 with dilute hydrochloric acid, and the sample was named AC-Pt-Au-C.

Results and discussion:

FIG. 1 is a schematic diagram of the synthesis of AC-Pt-Au, and FIG. 2 is a scanning electron micrograph of various samples, wherein (A) is an SEM image of tea residue activated carbon AC, and it can be clearly seen that tea residue becomes activated carbon having a porous structure after calcination by KOH activation. (B) Is an SEM picture of the AC-Pt-Au-H composite material prepared in example 1, (C) is an SEM picture of the AC-Pt-Au-J composite material prepared in example 2 by stirring, and (D) is an SEM picture of the AC-Pt-Au-C composite material prepared in example 3 by ultrasonic. From (B), it can be seen that the AC-Pt-Au composite material prepared by ultrasonic treatment has many small particles, namely nano-gold, distributed on the activated carbon, the particle size is about 5-10nm, and Pt is distributed on the surface of the AC-Pt-Au composite material together with Au by the displacement reaction with Au, and cannot be seen in the SEM picture due to the small particles. (C) And (D) respectively are AC-Pt-Au-J prepared by stirring and AC-Pt-Au-C prepared by ultrasonic treatment, and dense AuNPs are distributed on the surface of the activated carbon.

Fig. 3 is an isothermal adsorption-desorption curve of activated carbon, and fig. 4 is a distribution diagram of pore size of activated carbon. The isotherms of activated carbon are both typical type i and type iv isotherms and have a hysteresis curve indicating the coexistence of micropores and mesopores. And the specific surface area of the activated carbon after KOH activation is more than 1000 times higher than that of the activated carbon directly calcined without KOH activation, which provides larger specific surface area for the Au NPs loaded behind, and greatly improves the loading capacity of the AuNPs.

FIG. 5 is a Fourier infrared spectrum of AC and AC-Pt-Au with a peak at about 2920cm^-1、 2852cm^-1、1381cm^-1、1321cm^-1、1072cm^-1The point corresponds to the C-H stretching vibration and bending vibration group, 2169cm^-1And 1599cm^-1Respectively C ≡ C and C ═ C tensile vibration, peak 3423cm^-1And 1462cm^-1Stretching vibration of O-H.

FIG. 6 is a color development of AC-Pt-Au catalyzed TMB, with AC-Pt-Au + TMB on the left and AC-Pt-Au on the right, and the solution turned blue within two minutes after the addition of TMB to AC-Pt-Au, indicating that the AC-Pt-Au composite can generate OH radicals.

FIG. 7A is a schematic representation of the AC-Pt-Au catalytic reduction of MB (A is 1m L MB (10mg/m L) +400u L H2O, B is MB +200uLNaBH₄+200u L AC-Pt-Au, C is MB +200u L H₂O +200u L AC-Pt-Au, D is MB +200u L NaBH₄+200uLH₂O)。NaBH₄Has reducibility, can reduce MB from blue to colorless, but needs a certain time, and as can be seen from comparison of B and D, the addition of AC-Pt-Au (B) can catalyze NaBH₄MB was reduced and became colorless within two minutes, whereas MB could not be reduced within two minutes without the addition of AC-Pt-Au (D).

FIG. 8 is a graph showing the electrocatalytic activity at 0.5 mmol/L H for various electrodes₂SO₄And CV plot at sweep rate of 50 mV/s: a is a characterization diagram of oxygen reduction electrocatalytic activity of the bare glassy carbon electrode; and b is an electro-catalytic activity characterization diagram of the oxygen reduction of the AC-Pt-Au modified glassy carbon electrode. It can be seen from the figure that the bare glassy carbon electrode does not show any peak, while the AC-Pt-Au modified glassy carbon electrode shows a very obvious oxygen reduction peak at-0.23, which indicates that the AC-Pt-Au has stronger electrocatalytic activity.

Claims

1. A preparation method of a Pt-Au carbon-based in-situ reduction composite material is characterized in that,

(1) preparing porous activated carbon;

(2) synthesizing nanogold (AuNPs);

2. The method for preparing a Pt-Au carbon-based in-situ reduction composite material as claimed in claim 1, wherein the method for preparing porous activated carbon comprises: drying wet tea leaves to obtain tea leaves after primary drying, weighing a certain amount of tea leaves, carrying out hydrothermal carbonization for 3-10h, naturally cooling, taking out a sample for drying, mixing potassium hydroxide and the sample according to a certain proportion, adding a small amount of deionized water for dissolving, adding absolute ethyl alcohol for drying, putting the dried sample into a tube furnace, rapidly heating to 500-700 ℃ under the protection of argon, keeping the temperature for 3-5h, cleaning the obtained sample with HCl, washing with deionized water to the pH value of 6-7, finally drying at the temperature of 60-105 ℃, and finally sealing for storage.

3. The method for preparing the Pt-Au carbon-based in-situ reduction composite material as claimed in claim 1, wherein the method for synthesizing the nano-Au comprises the following steps: adding trisodium citrate into distilled water, and adding HAuCl₄Adding NaBH into ice water bath while stirring₄Until the color of the solution changes from orange red to wine red, and placing the solution in a conical flask for later use.

4. The preparation method of the Pt-Au carbon-based in-situ reduction composite material as claimed in claim 2, wherein the wet tea residue is dried at 60-105 ℃ for 15-24h to obtain primarily dried tea residue, 2-6 g of tea residue is weighed, 40m L of distilled water is added to be uniformly mixed, the mixture is placed into an autoclave and is subjected to hydrothermal carbonization at 180-220 ℃ for 3-10h, after natural cooling, the sample is taken out and dried at 60-105 ℃, potassium hydroxide and the sample are mixed according to a certain proportion, a small amount of deionized water is added to dissolve the potassium hydroxide and the sample, 2-5m 32 of anhydrous ethanol is added to be dried at 60-120 ℃ to obtain a dried sample, the dried sample is placed into a tubular furnace, under the protection of argon gas, the temperature is rapidly raised to 500-L ℃, the temperature is kept constant for 3-5h, the obtained sample is firstly cleaned by HCl, then is washed by deionized water to reach pH of 6-357, finally is dried at 60-105 ℃, and finally is sealed and stored.

5. The method for preparing Pt-Au carbon-based in-situ reduction composite material according to claim 3, wherein the method for synthesizing the nano-gold comprises the steps of adding 0.005-0.01g of trisodium citrate into 100m L of distilled water, and then adding 1-1.5m L HAuCl₄Adding 2.5m L NaBH into ice water bath with stirring₄(0.1M) until the color of the solution changes from orange red to wine red, and placing the solution in an erlenmeyer flask for later use.

6. The method of claim 1, wherein the PDDA is present at a concentration of 10%.

7. The method of claim 1, wherein the NaBH is added to the Pt-Au carbon-based in-situ reduction composite material₄The preparation method comprises dissolving 0.0166g in 1m L ice water, and using as it is.

8. The method of claim 2, wherein the ratio of potassium hydroxide to sample is 4: 1.

9. Pt-Au carbon-based in-situ reduction composite material for catalyzing NaBH₄Methylene blue is reduced.