阅读说明：本技术 Ni-Fe-Co-Ce四元PB析氧催化剂的制备方法 (Preparation method of Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst ) 是由 高发明 游欢欢 位阔 王博 李贺恩 于 2019-10-25 设计创作，主要内容包括：本发明公开一种析氧低过电位的无定型Ni-Fe-Co-Ce四元PB催化剂材料的制备方法,主要是在常温下通过匀相沉淀法,进行CeCo等金属间的掺杂,利用金属间的协同作用和磷化物硼化物间的共同作用,制备四元的PB催化剂使得电化学性能析氧过电位达到260mV,这在电化学催化剂领域具有很好的性能。本发明的目的是提供一种合成工艺简单,反应条件温和,重复性高,具有低过电位的无定型Ni-Fe-Co-Ce四元PB析氧催化剂,这对磷化物材料在电化学析氧催化剂领域中进一步发展具有重要意义。(The invention discloses a preparation method of an amorphous Ni-Fe-Co-Ce quaternary PB catalyst material with oxygen evolution low overpotential, which is mainly characterized in that intermetallic doping such as CeCo is carried out at normal temperature through a homogeneous precipitation method, and the quaternary PB catalyst is prepared by utilizing the synergistic effect between the intermetallic and the combined action between phosphide borides, so that the electrochemical performance oxygen evolution overpotential reaches 260mV, and the quaternary PB catalyst has good performance in the field of electrochemical catalysts. The invention aims to provide an amorphous Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst with simple synthesis process, mild reaction conditions, high repeatability and low overpotential, which has important significance for further development of phosphide materials in the field of electrochemical oxygen evolution catalysts.)

1. A preparation method of a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst is characterized by comprising the following steps: the method comprises the following steps:

(1) adding water to a cerium source, a cobalt source, an iron source and a nickel source according to the molar ratio of cerium to nickel to the cobalt to the iron to the nickel to obtain a mixed solution, wherein the molar ratio of cerium to the cobalt to the iron to the nickel is 3:1: 1-6: 2:3: 1;

(2) adding H into the mixed solution obtained in the step (1)₂O₂Standing until the solution becomes orange yellow, then adjusting the pH value of the solution to be more than or equal to 10, then adding a boron source solution with the concentration of 0.1-0.5 g/ml and a phosphorus source solution with the concentration of 0.1-0.5 g/ml, and stirring at 25 ℃ until the reaction is complete to obtain a mixture;

(3) standing the mixture obtained in the step (2) for 6-8 hours, centrifugally washing to be neutral, and drying the obtained sample at 70-100 ℃ for 6-12 hours under a vacuum condition;

wherein the mixed solution is mixed with H₂O₂The volume ratio of (A) to (B) is 8: 1-10: 1; the volume ratio of the mixed solution to the boron source solution is 3: 1-5: 1; the volume ratio of the mixed solution to the phosphorus source solution is 3: 1-5: 1.

2. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: the cerium source is at least one of cerium nitrate and cerium chloride.

3. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: the cobalt source is at least one of cobalt nitrate and cobalt chloride.

4. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: the iron source is at least one of ferric nitrate, ferric chloride and ferrous chloride.

5. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: the nickel source is at least one of nickel nitrate and nickel chloride.

6. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: the phosphorus source is at least one of sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate and sodium hypophosphite.

7. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: the boron source is at least one of potassium borohydride, sodium borohydride and magnesium diboride.

8. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: in the step (2), the time for standing until the solution becomes orange yellow is 5-10 minutes.

9. The method of preparing a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst of claim 1, wherein: in the step (3), the time for stirring at 25 ℃ until the reaction is completed is 3-6 hours.

Technical Field

The invention belongs to a preparation method of a multi-metal doped PB compound, and particularly relates to a preparation method of a Ni-Fe-Co-Ce quaternary PB compound applied to an oxygen evolution reaction.

Background

With the continuous and deep industrialization, the problems of excessive energy consumption and aggravation of environmental pollution are more and more prominent, and therefore, the search for new renewable energy sources which are safe, clean and efficient becomes one of the hot spots of research. As a zero-pollution renewable clean energy source, the development of water energy is placed in the strategic position of energy development in all countries in the world. The Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) in the field of electrochemical catalysis are the two half-reactions that constitute the water decomposition reaction. Among them, the OER process involves the transfer of four electrons, is a kinetic slow reaction process, requires a much higher overpotential than HER, and is a major factor affecting the water splitting efficiency, so the research of electrolyzing water to separate oxygen focuses on developing a high-efficiency catalyst for accelerating the reaction kinetics.

Currently, the most excellent OER catalytic performance is noble metal anode oxygen absorption materials, such as Ru and Ir, which have good and relatively stable OER activity, but because of limited reserves and high price, large-scale production cannot be realized, so we must find cheaper metals to replace noble metal materials as OER catalysts, and the development of efficient and stable transition metal electrocatalysts becomes a hot point of research in recent years. Multimetallic phosphide catalysts having an amorphous structure have been shown to have very interesting catalytic properties, and transition metal cation doping is an effective means to enhance the catalytic activity of phosphide electrocatalysts. Among them, transition metal phosphide has higher reactivity and good stability, and thus has gained more and more attention, however, the design of transition metal phosphide catalyst with low loading, high apparent activity and high intrinsic activity still faces huge challenges, and is also a difficult point in the research and development of such catalyst.

Disclosure of Invention

The invention aims to provide a preparation method of an amorphous Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst with simple synthesis process, mild reaction conditions, high repeatability and low overpotential.

The technical scheme of the invention is as follows:

a preparation method of a Ni-Fe-Co-Ce quaternary PB oxygen evolution catalyst comprises the following steps:

(1) adding water to a cerium source, a cobalt source, an iron source and a nickel source according to a molar ratio of cerium (Ce), cobalt (Co), iron (Fe) and nickel (Ni) of 3:1:1: 1-6: 2:3:1 until the cerium source, the cobalt source, the iron source and the nickel source are dissolved to obtain a mixed solution;

(2) adding H into the mixed solution obtained in the step (1)₂O₂Standing until the solution becomes orange yellow, then adjusting the pH value of the solution to be more than or equal to 10, then adding a boron source solution with the concentration of 0.1-0.5 g/ml and a phosphorus source solution with the concentration of 0.1-0.5 g/ml, and stirring at 25 ℃ until the reaction is complete to obtain a mixture;

(3) and (3) standing the mixture obtained in the step (2) for 6-8 hours, centrifugally washing to be neutral, and drying the obtained sample at 70-100 ℃ for 6-12 hours under a vacuum condition to obtain the amorphous Ni-Fe-Co-Ce quaternary PB catalyst with low overpotential.

Wherein, the mixed solution in the step (1) is mixed with H₂O₂The volume ratio of (a) to (b) is 8: 1-10: 1, preferably 10: 1; the volume ratio of the mixed solution in the step (1) to the boron source solution is 3: 1-5: 1, and preferably 4: 1; the volume ratio of the mixed solution in the step (1) to the phosphorus source solution is 3: 1-5: 1, and preferably 4: 1.

Based on the technical scheme, preferably, the cerium source is at least one of cerium nitrate and cerium chloride.

Based on the technical scheme, preferably, the cobalt source is at least one of cobalt nitrate and cobalt chloride.

Based on the technical scheme, preferably, the iron source is at least one of ferric nitrate, ferric chloride and ferrous chloride.

Based on the technical scheme, preferably, the nickel source is at least one of nickel nitrate and nickel chloride.

Based on the technical scheme, preferably, the phosphorus source is at least one of sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate and sodium hypophosphite.

Based on the above technical scheme, preferably, the boron source is at least one of potassium borohydride, sodium borohydride and magnesium diboride.

Based on the technical scheme, preferably, in the step (2), the time for standing until the solution becomes orange yellow is 5-10 minutes.

Based on the technical scheme, preferably, in the step (3), the time from stirring at 25 ℃ to complete reaction is 3-6 hours, and the precipitation is complete.

The oxygen evolution performance of the cobalt-doped cerium dioxide is improved compared with that of a pure cerium dioxide material, and NaBH is added at the same time₄The synergistic effect of the gases generated facilitates the reduction of the metal precursor. The invention effectively combines the two points, and improves the catalytic activity by changing the type and the proportion of the metal. The introduction of boron can increase the active surface area of the catalyst, and the boron and the phosphorus have synergistic effect in the Co-P-B catalyst.

Compared with the prior art, the invention has the following advantages:

1. the raw materials are simple and easy to obtain, the price is low, the reaction condition is mild, the preparation process is simple and feasible, and the repeatability is high.

2. The prepared quaternary PB catalyst material has a plurality of active sites, has a low oxygen evolution overpotential, and has an electrochemical performance oxygen evolution overpotential of 260mV, which is of great significance for further development of phosphide materials in the field of electrochemical oxygen evolution catalysts

3. Due to the coordination effect between metals, the catalytic performance can be influenced by adjusting the type and proportion of metal in-situ doping.

4. Can be produced in large scale and realize industrialization.

Drawings

FIG. 1 is a TEM image of an amorphous Ni-Fe-Co-Ce quaternary PB material prepared in example 1 of the present invention, which shows that the material has no fixed morphology and is stacked with random shapes.

FIG. 2 is a SEM picture of amorphous Ni-Fe-Co-Ce quaternary PB material obtained in example 1 of the present invention, and it is shown that the material has no regular shape.

Fig. 3 is an XRD chart of the materials prepared in example 1 and example 2 of the present invention and comparative example 1 and example 2, which shows that none of the four materials has distinct characteristic peaks and fixed lattice composition, and further shows that all of the four materials are amorphous.

Fig. 4 is an impedance diagram of the amorphous Ni-Fe-Co-Ce binary PB material obtained in example 2 of the present invention, and as shown in the figure, it is proved that the charge transfer resistance Rct of the material is 50 Ω, which indicates that the material has a smaller resistance and a better conductivity.

FIG. 5 is a polarization curve of amorphous materials obtained in examples 1 and 2 of the present invention and comparative examples 1 and 2, and it can be seen that the polarization curve is 10mV/cm²Under the current density, the oxygen evolution overpotentials of example 1, comparative example 1, example 2 and comparative example 2 are 326mV, 354mV, 260mV and 390mV respectively, and the commercial RuO₂(CAS:12036-10-1) oxygen evolution overpotential of 284mV, the oxygen evolution overpotential ratio of example 2 to commercial RuO₂The oxygen evolution overpotential is 24mV lower.

FIG. 6 is Tafel plot of amorphous Ni-Fe-Co-Ce quaternary PB material obtained in example 2 of the present invention with a Tafel slope of 69 mV/dec.

FIG. 7 is a CV curve of amorphous Ni-Fe-Co-Ce quaternary PB material prepared in example 2 of the present invention, which shows that the peak variation and peak shift of the curve occur in the low scan speed range, the peak difference increases, the polarization phenomenon exists, and the polarization degree increases with the increase of the scan speed.

Detailed Description

The following non-limiting examples will allow one of ordinary skill in the art to more fully understand the present invention, but are not intended to limit the invention in any way.