阅读说明：本技术 一种多孔二磷化五钯纳米棒的制备方法及其应用 (Preparation method and application of porous pentapalladium diphosphide nanorod ) 是由 王新 陈忠伟 于 2021-10-11 设计创作，主要内容包括：本发明属于燃料电池的技术领域,具体的涉及一种多孔Pd-(5)P-(2)纳米棒的制备方法及其应用。该制备方法以Pd(II)-DMG为前驱体,在氢气气氛下还原得到多孔Pd纳米棒,再以次亚磷酸钠为磷源进行磷化得到多孔Pd-(5)P-(2)纳米棒。所得多孔Pd-(5)P-(2)纳米棒对甲酸电氧化反应呈现出较高的电催化活性。(The invention belongs to the technical field of fuel cells, and particularly relates to porous Pd 5 P 2 A preparation method and application of the nano-rod. The preparation method takes Pd (II) -DMG as a precursor, and the Pd (II) -DMG is reduced in hydrogen atmosphere to obtain porous Pd nano-rods, and then sodium hypophosphite is taken as a phosphorus source to carry out phosphorization to obtain porous Pd 5 P 2 And (4) nanorods. The resulting porous Pd 5 P 2 The nano-rod shows higher electrocatalytic activity to formic acid electrooxidation reaction.)

1. Porous Pd₅P₂The preparation method of the nanorod is characterized by comprising the steps of firstly preparing a dimethylglyoxime ethanol solution and a palladium chloride aqueous solution, pouring the dimethylglyoxime ethanol solution into the palladium chloride aqueous solution, uniformly mixing at normal temperature, standing to enable the palladium chloride and dimethylglyoxime to be fully complexed, then carrying out ultrasonic treatment to obtain a dimethylglyoxime palladium precursor with uniform size, centrifugally washing the dimethylglyoxime palladium precursor, then placing the dimethylglyoxime palladium precursor into a magnetic boat for drying, then placing the magnetic boat into a tubular furnace, and reacting for 1.5-2 hours under the condition that the temperature is 180-200 ℃ and the reducing agent is a hydrogen atmosphere to reduce the dimethylglyoxime palladium precursor to obtain the porous Pd nanorod; then placing the solid powder of the porous Pd nano-rod and phosphorus source sodium hypophosphite on two sides of a magnetic boat, placing the two sides of the magnetic boat into a tubular furnace, reacting for 1-2 hours at 300-350 ℃ in a nitrogen atmosphere for phosphorization, centrifugally washing for 4-5 times by adopting ultrapure water, and drying in vacuum at 60 ℃ to obtain the porous Pd₅P₂And (4) nanorods.

2. Porous Pd as in claim 1₅P₂The preparation method of the nano rod is characterized in that the concentrations of the dimethylglyoxime ethanol solution and the palladium chloride aqueous solution are both 0.05 mol/L.

3. Porous Pd as in claim 1₅P₂The preparation method of the nanorod is characterized in that the molar ratio of the palladium chloride to the dimethylglyoxime is 1: 1.5-3.

4. Porous Pd as in claim 1₅P₂The preparation method of the nanorod is characterized in that the hydrogen atmosphere is hydrogen-argon mixed gas, wherein the volume fraction of hydrogen is at least 5%.

5. Porous Pd as in claim 1₅P₂The preparation method of the nanorod is characterized in that the heating speed is 10-20 ℃/min in the process of reducing the palladium dimethylglyoxime precursor.

6. Porous Pd as in claim 1₅P₂The preparation method of the nanorod is characterized in that the molar ratio of the porous Pd nanorod to the sodium hypophosphite is 1: 5.

7. Porous Pd as in claim 1₅P₂The preparation method of the nano-rod is characterized in that the temperature rise speed in the phosphorization process is 2 ℃/min.

8. Porous Pd prepared by the method of claim 1₅P₂Nanorods, characterized in that the porous Pd₅P₂The surface of the nano rod is rough and porous.

9. Porous Pd prepared by the method of claim 1₅P₂Application of nano-rod in anode material of formic acid fuel cellThe application is as follows.

10. Porous Pd prepared by the method of claim 1₅P₂The nanorod is used as a catalyst in the formic acid electrooxidation reaction.

Technical Field

The invention belongs to the technical field of fuel cells, and particularly relates to porous Pd₅P₂A preparation method and application of the nano-rod.

Background

Formic acid fuel cells are widely used because of their advantages such as high theoretical open circuit voltage, convenient fuel storage, low operating temperature, etc. The formic acid electrooxidation reaction is used as the anode reaction exclusive to the formic acid fuel cell and plays an important role in the power density and the service life of the equipment. The formic acid electro-oxidation reaction occurs through two reaction mechanisms, namely, direct and indirect routes, wherein the indirect route containing a strongly toxic intermediate greatly reduces the efficiency of the formic acid fuel cell. The platinum-based nano material has high stability and can catalyze formic acid electrooxidation reaction. However, platinum surfaces are easily adsorbed by toxic intermediates and indirect pathways are easily generated. As a potential alternative to platinum-based electrocatalysts, palladium (Pd) -based electrocatalysts tend to promote formic acid electrooxidation reactions via a direct route with fewer toxic intermediates.

The activity of the electrocatalyst is highly related to the morphology and composition of the electrocatalyst, and in order to improve the electrocatalytic performance, proper component regulation and control on the Pd-based nanostructure is an effective strategy. Metal phosphides generally have higher activity and stability than pure metals, since the P element is able to adjust its external electronic structure by interacting with the metal particles. For the formic acid electrooxidation reaction, the introduction of P causes the d-band center of metal Pd to move negatively, thereby weakening the adsorption of formate on Pd sites and promoting the direct path formic acid electrooxidation. Furthermore, metal phosphides generally exhibit a certain corrosion resistance, which makes them excellent in durability in acidic and basic media, thus contributing to an increase in the stability of the electrocatalyst.

The performance of the Pd-based electrocatalyst can be further improved through a morphology control strategy, so that more active centers are exposed, and the utilization rate of Pd atoms is improved to the maximum extent. Porous nanorods have many advantages in catalysis and electrocatalysis due to their unique physicochemical properties. The porous structure characteristics enable the catalyst to have larger surface area and more edge/step atoms with high electric activity, and can effectively promote infiltration and diffusion of reaction molecules and electrolyte solution and accelerate mass transfer of catalytic reaction. Meanwhile, the one-dimensional nanorod structure can form a continuous conductive network on the surface of the electrode, so that the reaction kinetics of various electrocatalytic reactions are promoted. In addition, the self-supporting structure characteristic of the one-dimensional continuous structure has excellent self-stability, and is beneficial to improving the electrochemical stability in the catalytic reaction process.

In conclusion, compared with the traditional spherical nanocrystals, the innovative design of a simple and convenient method suitable for industrial preparation and production of one-dimensional porous palladium phosphide nanorods becomes a problem to be solved in further development of formic acid fuel cells.

Disclosure of Invention

The present invention aims to provide a porous Pd for overcoming the above-mentioned drawbacks₅P₂Preparation method and application of nanorod, and porous Pd is simply prepared by taking palladium dimethylglyoxime as template₅P₂Nanorods, resulting in porous Pd₅P₂The nano-rod shows higher electrocatalytic activity to formic acid electrooxidation reaction.

The technical scheme of the invention is as follows: porous Pd₅P₂Firstly, preparing a dimethylglyoxime ethanol solution and a palladium chloride aqueous solution, pouring the dimethylglyoxime ethanol solution into the palladium chloride aqueous solution, uniformly mixing at normal temperature, standing to ensure that palladium chloride is fully complexed with dimethylglyoxime, then carrying out ultrasonic treatment to obtain a dimethylglyoxime palladium precursor with uniform size, centrifugally washing the dimethylglyoxime palladium precursor, then placing the dimethylglyoxime palladium precursor into a magnetic boat for drying, then placing the magnetic boat into a tubular furnace, and reacting for 1.5-2 hours under the conditions that the temperature is 180-200 ℃ and the reducing agent is a hydrogen atmosphere to reduce the dimethylglyoxime palladium precursor to obtain the porous Pd nanorod; then placing the solid powder of the porous Pd nano-rod and phosphorus source sodium hypophosphite on two sides of a magnetic boat, placing the two sides of the magnetic boat into a tubular furnace, reacting for 1-2 hours at 300-350 ℃ in a nitrogen atmosphere for phosphorization, centrifugally washing for 4-5 times by adopting ultrapure water, and drying in vacuum at 60 ℃ to obtain the porous Pd₅P₂And (4) nanorods.

The concentrations of the dimethylglyoxime ethanol solution and the palladium chloride aqueous solution are both 0.05 mol/L.

The molar ratio of the palladium chloride to the dimethylglyoxime is 1: 1.5-3.

The hydrogen atmosphere is hydrogen and argon mixed gas, wherein the volume fraction of hydrogen is at least 5%.

The heating speed in the process of reducing the palladium dimethylglyoxime precursor is 10-20 ℃/min.

The molar ratio of the porous Pd nano rod to the sodium hypophosphite is 1: 5.

The temperature rise speed in the phosphorization process is 2 ℃/min.

The porous Pd₅P₂The surface of the nano rod is rough and porous.

Porous Pd prepared by the method₅P₂The application of the nano-rod in anode materials of formic acid fuel cells.

Porous Pd prepared by the method₅P₂The nanorod is used as a catalyst in the formic acid electrooxidation reaction.

The invention has the beneficial effects that: the method comprises the steps of mixing Dimethylglyoxime (DMG) serving as a complexing agent, palladium chloride serving as a palladium source and ethanol and water serving as solvents at normal temperature to obtain a palladium dimethylglyoxime (Pd (II) -DMG) precursor; reducing Pd (II) -DMG at 180-200 ℃ by using hydrogen as a reducing agent to obtain porous Pd nanorods; then, sodium hypophosphite is used as a phosphorus source to phosphorize the porous Pd nano rod at the temperature of 300-350 ℃ to obtain porous Pd₅P₂And (4) nanorods.

Using PdCl₂And strong complexation of DMG, namely mixing the Pd- (II) -DMG complex precipitate with the DMG at normal temperature to obtain yellow Pd- (II) -DMG complex precipitate which has a uniform rod-shaped structure with a smooth surface, and calcining the yellow Pd- (II) -DMG complex precipitate serving as a template by using hydrogen as a reducing agent to obtain black solid powder serving as a porous Pd nanorod. During the sintering process, the removal of a large amount of DMG is helpful for the formation of the surface pore structure of the Pd-PdO nanorod. High-temperature calcination is carried out by taking sodium hypophosphite as phosphorus source to obtain porous Pd₅P₂And (4) the nanorod is successfully introduced with P. The method is simple and green, and the synthesized porous Pd₅P₂The nano-rod has obvious advantages of appearance and components.

Porous Pd prepared by the invention₅P₂The nano-rod has abundant pore structures and grain boundary atoms, shows abundant active centers and can promote formic acid oxidation in a direct way. Thus, porous Pd₅P₂The nanorods exhibited enhanced formic acid oxidation reactivity (216.6A. g)^-1) The peak potential of the anode material is 1.3 times that of the commercial Pd black, and the anode material is a promising anode material for formic acid fuel cells.

Drawings

FIG. 1 is porous Pd prepared in example 1₅P₂XRD pattern of the nanorods.

FIG. 2 is porous Pd prepared in example 1₅P₂SEM image of nanorods.

Fig. 3 is a partially enlarged view of fig. 2.

FIG. 4 is porous Pd prepared in example 2₅P₂SEM image of nanorods.

FIG. 5 shows porous Pd prepared in example 1₅P₂Cyclic voltammograms of the nanorods electrocatalytic oxidation of formic acid with commercial Pd black catalysts.

Detailed Description

The invention will be further described in detail with reference to the following figures and examples, to which, however, the scope of the invention is not limited.

Example 1

Pouring 6mL of 0.05mol/L dimethylglyoxime ethanol solution into 3mL of 0.05mol/L palladium chloride aqueous solution, uniformly mixing, standing the obtained mixed solution for 1-2 min to fully complex the palladium chloride and the dimethylglyoxime to form a palladium dimethylglyoxime precursor, and carrying out ultrasonic treatment for 10min to ensure that the palladium dimethylglyoxime precursor is uniform in size; then, the mixture of water and ethanol is used for centrifugal washing for 3 times, and then the mixture is poured into a magnetic boat to be dried in an oven at 60 ℃; and (3) putting the magnetic boat into a tube furnace, and calcining for 2 hours at 200 ℃ under the hydrogen atmosphere condition with the hydrogen volume fraction of at least 5% to obtain the black solid porous Pd nanorod. Weighing 10mg Pd nano-rod and 50mg sodium hypophosphite, respectively placing the Pd nano-rod and the sodium hypophosphite into the left side and the right side of a magnetic boat, wrapping the magnetic boat with tinfoil, placing the magnetic boat into a tube furnace, and calcining the magnetic boat for 2 hours at 300 ℃ under the nitrogen condition to obtain black solid, namely porous Pd₅P₂And (4) nanorods.

As can be seen from FIG. 1, the XRD diffraction peak of the obtained product corresponds to that of standard card PDF #00-019-₅P₂。

As can be seen from FIG. 2, the resulting product has a one-dimensional rod-like structure.

Pd can be seen by observation in FIG. 3₅P₂The surface of the nano rod is rough and has a plurality of holes.

Example 2

Pouring 4mL of 0.05mol/L dimethylglyoxime ethanol solution into 2mL of 0.05mol/L palladium chloride aqueous solution, uniformly mixing, standing the obtained mixed solution for 1-2 min to fully complex the palladium chloride and the dimethylglyoxime to form a dimethylglyoxime palladium precursor, and carrying out ultrasonic treatment for 10min to ensure that the dimethylglyoxime palladium precursor is uniform in size; then centrifugal washing is carried out for 3 times by using a mixed solution of water and ethanol,then pouring the mixture into a magnetic boat and drying the mixture in a baking oven at 60 ℃; and (3) putting the magnetic boat into a tube furnace, and calcining for 2 hours at 190 ℃ under the hydrogen atmosphere condition that the volume fraction of hydrogen is at least 5%, so as to obtain the black solid porous Pd nano rod. Weighing 6mg Pd nano-rod and 30mg sodium hypophosphite, respectively placing the Pd nano-rod and the sodium hypophosphite into the left side and the right side of a magnetic boat, wrapping the magnetic boat with tinfoil, placing the magnetic boat into a tube furnace, and calcining the magnetic boat for 2 hours at 300 ℃ under the nitrogen condition to obtain black solid, namely porous Pd₅P₂Nanorods, see FIG. 4.

Porous Pd prepared in example 1₅P₂The nanorods electrocatalyze the formic acid oxidation reaction at 30 ℃ and adopt cyclic voltammetry test, and the result is shown in figure 5. Due to the porous Pd prepared by the invention₅P₂The nano-rod has abundant pore structures and grain boundary atoms, shows abundant active centers and can promote formic acid oxidation in a direct way. Thus, compared to commercial Johnson-Matthey Pd black (commercial Pd black for short) catalyst, porous Pd₅P₂The nanorods exhibited enhanced formic acid electrooxidation kinetics, a more negative onset oxidation potential and 216.6A-g^-1The peak value potential of the mass activity of the catalyst is 1.3 times of that of commercial Pd black, and the catalytic performance is obviously improved.