阅读说明：本技术 一种氰基修饰的三维钯铜纳米珊瑚及其制备方法与应用 (Cyano-modified three-dimensional palladium-copper nano coral and preparation method and application thereof ) 是由 付更涛 刘启成 林梓楠 黄秋子 周心怡 唐亚文 于 2021-08-02 设计创作，主要内容包括：本发明公开了一种氰基修饰的三维钯铜纳米珊瑚及其制备方法与应用。具体方法以下步骤：以钯氰化盐和铜盐作为前驱体,硼氢化钠作为还原剂,常温静置还原得氰基修饰的三维钯铜纳米珊瑚。与传统制备方法相比,本发明方法工艺操作简单易合成,用去离子水即可除去溶液中的杂离子。本发明方法制备得氰基修饰的三维钯铜纳米珊瑚的形貌单一,纯度极高,可高通量生产制备,样品具有比表面积大,活性位点多,结构稳定等优点,对甲酸氧化展现出优异的电催化活性。(The invention discloses cyano-modified three-dimensional palladium-copper nano coral and a preparation method and application thereof. The method comprises the following steps: and (3) taking palladium cyanide and copper salt as precursors and sodium borohydride as a reducing agent, and standing and reducing at normal temperature to obtain the cyano-modified three-dimensional palladium-copper nano coral. Compared with the traditional preparation method, the method has simple process operation and easy synthesis, and can remove the impurity ions in the solution by using deionized water. The cyano-modified three-dimensional palladium-copper nano coral prepared by the method has the advantages of single appearance, extremely high purity, high-throughput production and preparation, large specific surface area of a sample, many active sites, stable structure and the like, and shows excellent electrocatalytic activity on formic acid oxidation.)

1. A preparation method of cyano-modified three-dimensional palladium-copper nano coral is characterized in that palladium cyanide salt and copper salt are used as precursors, sodium borohydride is used as a reducing agent, and the cyano-modified three-dimensional palladium-copper nano coral is obtained by standing and reducing at normal temperature.

2. The preparation method of the cyano-modified three-dimensional palladium-copper nano coral according to claim 1, comprising the following steps:

step 1, preparation of PdCu cyanogen glue

The concentration is 0.03-0.20 mol. L in the ultrasonic process^-1Adding palladium cyanide salt solution into the solution with concentration of 0.03-0.20 mol.L^-1A copper salt solution ensuring a molar ratio of palladium to copper of 1: 2, finishing ultrasonic stirring when the copper salt solution is added, and ensuring that the ultrasonic time cannot be keptThe time for mixing the palladium cyanide salt solution and the copper salt solution is exceeded, then the mixture is kept stand for 10min to obtain PdCu cyanide adhesive, the temperature of the adhesive preparation environment is not lower than 0 ℃, and the release of cyanide gas is avoided within the temperature range of safe use of cyanide;

step 2, preparing three-dimensional PdCu nano coral

Adding excessive new preparation with concentration of 0.1-0.50 mol · L^-1Adding the sodium borohydride solution into PdCu cyanogen glue, standing for 12 h, and washing for 3-5 times to obtain the cyano-modified three-dimensional palladium-copper nano coral.

3. The method for preparing cyano-modified three-dimensional palladium-copper nano coral according to claim 1, wherein the palladium cyanide salt in step 1 is potassium palladium cyanide, and the copper salt is copper chloride.

4. The cyano-modified three-dimensional palladium-copper nano coral prepared by the preparation method of any one of claims 1 to 3.

5. Use of three-dimensional palladium-copper nano-coral based on cyano modification according to any one of claims 1 to 4 for oxidation catalysis of formic acid.

Technical Field

The invention particularly relates to cyano-modified three-dimensional palladium-copper nano coral and a preparation method and application thereof, belonging to the technical field of catalysts for formic acid oxidation.

Background

Environmental pollution and energy crisis are becoming more serious, and the significant advantages of high energy efficiency and low emission of fuel cell technology are receiving wide attention. The direct formic acid fuel cell uses formic acid as fuel, and the energy density of the direct formic acid fuel cell is 3 times of that of the direct methanol fuel cell. The electrochemical oxidation of formic acid can be carried out by a direct route, so that the catalyst is not easy to be poisoned, and the direct formic acid fuel cell can work at low temperature because the freezing point of formic acid is low. The key to achieving this assumption is the development of improved electrocatalysts with appropriate efficiency and selectivity for the chemical conversions involved.

The current commercialized catalyst for electrochemical formic acid anodic oxidation is Pd black, but the development of the catalyst is restricted due to the defects of low natural abundance and high cost of noble metals.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide the cyano-modified three-dimensional palladium-copper nano coral and the preparation method and the application thereof, the obtained cyano-modified three-dimensional palladium-copper nano coral has regular appearance and can be produced and prepared in high flux, the three-dimensional Pd-Cu nano coral has the advantages of large specific surface area, many active sites and the like, the preparation process is simple and easy to implement, and the reproducibility is good.

In order to solve the problems of the prior art, the invention adopts the technical scheme that:

a preparation method of cyano-modified three-dimensional palladium-copper nano coral is characterized by taking palladium cyanide salt and copper salt as precursors and sodium borohydride as a reducing agent, and standing and reducing at normal temperature to obtain the cyano-modified three-dimensional palladium-copper nano coral.

The preparation method of the three-dimensional Pd-Cu nano coral comprises the following steps:

step 1, preparation of PdCu cyanogen glue

The concentration of the ultrasonic wave is 0.03-0 in the ultrasonic process.20 mol• L^-1Adding palladium cyanide salt solution into the solution with concentration of 0.03-0.20 mol.L^-1A copper salt solution ensuring a molar ratio of palladium to copper of 1: 2, finishing ultrasonic stirring while adding the copper salt solution, ensuring that the ultrasonic time does not exceed the time for mixing the palladium cyanide salt solution and the copper salt solution, standing for 10min to obtain PdCu cyanide adhesive, wherein the temperature of the adhesive preparation environment is not lower than 0 ℃, and the release of cyanide is avoided within the temperature range of safe use of cyanide;

step 2, preparing three-dimensional PdCu nano coral

Adding excessive new preparation with concentration of 0.1-0.50 mol · L^-1Adding the sodium borohydride solution into PdCu cyanogen glue, standing for 12 h, and washing for 3-5 times to obtain the cyano-modified three-dimensional palladium-copper nano coral.

In a modification, in step 1, the palladium cyanide salt is potassium palladium cyanide, and the copper salt is copper chloride.

The cyano-modified three-dimensional palladium-copper nano coral is prepared based on the preparation method.

The application of the cyano-modified three-dimensional palladium-copper nano coral in oxidizing and catalyzing formic acid.

Has the advantages that:

compared with the prior art, the cyano-modified three-dimensional palladium-copper nano coral and the preparation method and the application thereof have the following advantages:

1. the method has simple process operation and easy synthesis, can remove the impurity ions in the solution by using deionized water, is environment-friendly and pollution-free, can be used for high-throughput production and preparation, and not only can the activity and the stability of the catalyst be remarkably improved, but also the cost of the catalyst can be effectively reduced by alloying non-noble metal and noble metal;

2. the cyano-modified three-dimensional palladium-copper nano coral prepared by the method belongs to a cyano-surface functionalized palladium-copper alloy, has extremely high purity, has the advantages of large specific surface area, many active sites, stable structure and the like, and shows excellent electrocatalytic activity on formic acid oxidation;

3. in the preparation process of the palladium-copper cyanide-containing adhesive, the problem of uneven mixing is solved by adopting short-time ultrasound because the gelling speed is too high, but the colloid structure cannot be damaged in the gelling process, so that the ultrasound and standing are required to be immediately finished after the reagent is added, the uniformity of the cyanide-containing adhesive framework is ensured, and a good technical basis is provided for subsequent experiments.

Drawings

FIG. 1 is an SEM image of cyano-modified three-dimensional palladium-copper nano-coral prepared in example 5 of the present invention;

FIG. 2 is an XRD pattern of cyano-modified three-dimensional palladium-copper nano-coral prepared in example 5 of the present invention;

FIG. 3 is a CV curve of 0.5M sulfuric acid electrolyte of cyano-modified three-dimensional Pd-Cu nano-coral prepared in example 5 of the present invention;

FIG. 4 is the formic acid oxidation electrochemical performance (mass specific activity) of cyano-modified three-dimensional palladium-copper nano coral prepared in example 5 of the present invention;

FIG. 5 shows the formic acid oxidation electrochemical performance (specific area activity) of cyano-modified three-dimensional palladium-copper nano-coral prepared in example 5 of the present invention;

FIG. 6 is an infrared spectrum of cyano-modified three-dimensional palladium-copper nano-coral prepared in example 5 of the present invention;

FIG. 7 is a BET plot of cyano-modified three-dimensional palladium-copper nanocoral prepared in example 5 of the present invention.

Detailed Description

The technical solutions of the present invention are further described in detail by the following specific examples, but it should be noted that the following examples are only used for describing the content of the present invention and should not be construed as limiting the scope of the present invention.

Example 1

A preparation method of cyano-modified three-dimensional palladium-copper nano coral comprises the following steps:

1) preparation of PdCu cyanogen glue

To 0.3mL, the concentration was 0.03 mol. L^-10.6mL of potassium palladium cyanide solution with a concentration of 0.03 mol.L was rapidly added^-1The copper chloride solution is added from the beginning, ultrasonic stirring is started, after the addition is finished, the ultrasonic stirring is stopped, PdCu cyanogen glue is obtained for 10min, the temperature of a glue making environment is not lower than 0 ℃, and the ultrasonic stirring time is ensured not to exceed the former timeMixing the precursor solution for a time;

2) preparation of three-dimensional PdCu nano coral

Taking 0.3mL of fresh solution with the concentration of 0.1 mol L^-1Adding the sodium borohydride solution into PdCu cyanogen glue, standing for 12 h, and washing for 3-5 times to obtain the cyano-modified three-dimensional palladium-copper nano coral.

Example 2

The concentrations of the potassium palladium cyanide solution and the copper chloride solution were changed to 0.04 mol.L^-1Otherwise, the same procedure as in example 1 was repeated.

Example 3

Except that the concentrations of the potassium palladium cyanide solution and the copper chloride solution are changed to 0.05 mol.L^-1The same procedure as in example 1 was repeated except that the volume of the sodium borohydride solution was changed to 0.5 mL.

Example 4

The concentration of the potassium cyanide solution and the copper chloride solution except palladium is changed to 0.08mol^-1The volume of the potassium palladium cyanide solution is changed to 0.5mL, the volume of the copper chloride solution is 1.0mL, and the concentration of the sodium borohydride solution is changed to 0.2 mol.L^-1Otherwise, the same procedure as in example 1 was repeated.

Example 5

The concentrations of the potassium palladium cyanide solution and the copper chloride solution were changed to 0.1 mol^-1The concentration of the sodium borohydride solution is 0.2 mol^-1The same as example 1 except that the volume is 0.5mL, the abbreviation of the three-dimensional Pd-Cu nano coral is: PdCu NaBH₄。

Example 6

The concentrations of the potassium palladium cyanide solution and the copper chloride solution were changed to 0.15 mol. L^-1The volume of the potassium palladium cyanide solution is 0.8 mL, and the volume of the copper chloride solution is 1.6 mL; the concentration of the sodium borohydride solution is 0.3 mol.L^-1The same procedure as in example 1 was repeated except that the volume was 1.0 mL.

Example 7

The volume of the potassium palladium cyanide solution is 0.8 mL, and the concentration is 0.16 mol L^-1The volume of the copper chloride solution was 1.6 mL and the concentration was 0.16 mol. L^-1The concentration of the sodium borohydride solution is 0.5 mol^-1The same procedure as in example 1 was repeated except that the volume was 1.0 mL.

Example 8

The volume of the potassium palladium cyanide solution is 0.8 mL, and the concentration is 0.2 mol.L^-1The volume of the copper chloride solution was 1.6 mL and the concentration was 0.2 mol. L^-1The concentration of the sodium borohydride solution is 0.8 mol.L^-1The same procedure as in example 1 was repeated except that the volume was 1.0 mL.

Performance testing

The cyano-modified three-dimensional palladium-copper nanocoral prepared in example 5 above was physically characterized by SEM and XRD. As can be seen from SEM (figure 1), the catalyst prepared by the method of the invention is cyano-modified three-dimensional palladium-copper nano coral, the three-dimensional network structure has excellent stability, and a larger specific surface area can be provided (as shown in figure 7, the specific surface area is 174.96 cm^-2·g^-1) And more active sites. The existing 0-dimensional catalyst (the shape is nano-particles) based on Pd and Cu is easy to generate agglomeration dissolution and Ostwald ripening, but the catalyst of the invention does not have the problem, which provides good guarantee for subsequent application.

FIG. 2 is an XRD (X-ray diffraction) spectrum of cyano-modified three-dimensional palladium-copper nano coral, compared with a standard spectrum, diffraction peaks of a catalyst are respectively arranged on two sides of a Pd and Cu standard card and are palladium-copper alloy, and an ICP (inductively coupled plasma) test result proves that the sample is PdCu₂ (111)。

FIG. 3 is a cyclic voltammogram of cyano-modified three-dimensional palladium-copper nanocorals, measured in 0.5M sulfuric acid solution, exhibiting a larger electrochemically active area than commercial Pd black. The operation here can not only demonstrate the larger electrochemically active area of the present invention compared to the commercial Pd black catalyst, but also clean the electrode surface, activating the catalyst. .

FIGS. 4 and 5 are formic acid oxidation curves of cyano-modified three-dimensional Pd-Cu nano-coral, wherein the electrolyte is a mixture of 0.5M sulfuric acid and 0.5M formic acid, and it can be seen that the formic acid oxidation potential of cyano-modified three-dimensional Pd-Cu nano-coral is almost consistent with that of commercialization, the specific activity of the cyano-modified three-dimensional Pd-Cu nano-coral is 10 times that of commercialized Pd black (Johnson Matthey, USA), and the specific activity of the cyano-modified three-dimensional Pd-Cu nano-coral is 3.5 times that of commercialized Pd black (Johnson Matthey, USA). As can be seen from fig. 4, the current density advantage of the present invention is evident from the graph.

FIG. 6 is an infrared spectrum of cyano-modified three-dimensional palladium-copper nano-coral according to embodiment of the invention, which is at 2151cm^-1The existence of a more obvious cyano peak proves that the catalyst is a cyano surface functionalized catalyst, and the reason that the cyano peak is weaker can be concluded that the catalyst is in a nanometer level (black powder) and has strong light absorption capacity.

In conclusion, the method has simple process operation and easy synthesis, and can remove the impurity ions in the solution by using the deionized water. The cyano-modified three-dimensional palladium-copper nano coral prepared by the method has the advantages of single appearance, extremely high purity, high-throughput production and preparation, large specific surface area of a sample, many active sites, stable structure and the like, and shows excellent electrocatalytic activity on formic acid oxidation.

The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and any simple modifications or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope of the present invention are within the scope of the present invention.