阅读说明：本技术 一种具有多层级孔洞结构的磷化镍复合物及其制备方法和应用 (Nickel phosphide compound with multi-level hole structure and preparation method and application thereof ) 是由 张京涛 张珍 陈颖 于 2020-04-22 设计创作，主要内容包括：本发明涉及一种具有多层级孔洞结构的磷化镍复合物及其制备方法和应用。该磷化镍复合物包括金属泡沫骨架和金属泡沫骨架表面覆盖的磷化镍复合物微米片；金属泡沫骨架间分布有平均孔径为50～500μm的贯穿大孔,金属泡沫骨架表面分布有10～100μm的大孔；磷化镍复合物微米片上分布有纳米孔洞。本发明提供的磷化镍复合物具有多层级孔洞结构,其中贯穿大孔有利于电解质的传递和气体扩散,大孔及纳米孔洞有利于暴露更多的活性位点并增加与电解液的接触,加快反应速率。该磷化镍复合物可以作为工作电极用于电化学分解水产氢,且在全pH下均展现出优异的析氢性能,具有低成本,电催化析氢性能优异和稳定性强的优点。(The invention relates to a nickel phosphide compound with a multi-level hole structure, and a preparation method and application thereof. The nickel phosphide compound comprises a metal foam framework and nickel phosphide compound micron sheets covered on the surface of the metal foam framework; penetrating macropores with the average pore diameter of 50-500 mu m are distributed among the metal foam frameworks, and macropores with the average pore diameter of 10-100 mu m are distributed on the surfaces of the metal foam frameworks; nanometer holes are distributed on the nickel phosphide compound micron sheet. The nickel phosphide compound provided by the invention has a multi-level hole structure, wherein the through macropores are beneficial to the transfer of electrolyte and gas diffusion, and the macropores and the nano holes are beneficial to exposing more active sites, increasing the contact with the electrolyte and accelerating the reaction rate. The nickel phosphide compound can be used as a working electrode for electrochemically decomposing water to produce hydrogen, shows excellent hydrogen evolution performance under full pH, and has the advantages of low cost, excellent electro-catalytic hydrogen evolution performance and strong stability.)

1. The nickel phosphide compound with the multi-level hole structure is characterized by comprising a metal foam framework and nickel phosphide compound micron sheets covered on the surface of the metal foam framework; penetrating macropores with the average pore diameter of 50-500 mu m are distributed among the metal foam frameworks, and macropores with the average pore diameter of 10-100 mu m are distributed on the surfaces of the metal foam frameworks; nanometer holes are distributed on the nickel phosphide compound micron sheet.

2. The nickel phosphide composite of claim 1, wherein the metal foam skeleton is a nickel foam skeleton, a copper foam skeleton, a cobalt foam skeleton or an iron foam skeleton.

3. The nickel phosphide composite according to claim 1, wherein the macropores are formed by a metal plating layer; the metal coating is a nickel layer, a copper layer, a cobalt layer or an iron layer.

4. The nickel phosphide composite of claim 1, wherein the nickel phosphide composite micron-sheets are composed of Ni₂P and Ni₁₂P₅Composition is carried out; pores of the nano-poresThe diameter is 60 to 600 nm.

5. The method for preparing a nickel phosphide complex as set forth in any one of claims 1 to 4, characterized by comprising the steps of:

s1: the metal foam is subjected to constant current treatment to deposit metal on the surface of the metal foam and form macropores, and the current density of the constant current treatment is-0.5A-cm^-2～-2A·cm^-2(ii) a The treatment time is 100-1000 s;

s2: immersing the metal foam obtained in the step S1 into a mixed solution of a nickel source and organic amine, carrying out hydrothermal reaction at the temperature of 80-120 ℃ for 1-10 h, washing and drying;

s3: and (4) mixing the metal foam obtained in the step (S2) with a phosphorus source, and keeping the temperature at 250-400 ℃ for 0.5-4 h to obtain the nickel phosphide compound.

6. The method of claim 5, wherein the metal foam of S1 further comprises ultrasonic treatment before constant current treatment.

7. The preparation method according to claim 5, wherein the nickel source in S2 is one or more of nickel nitrate, nickel sulfate or nickel chloride; the organic amine source is one or more of hexamethylenetetramine, diethylenetriamine or triethylenediamine.

8. The preparation method of claim 5, wherein the phosphorus source in S3 is one or more of sodium hypophosphite or red phosphorus.

9. The method according to claim 5, wherein the reaction in S3 is performed in an inert gas atmosphere, and the flow rate of the inert gas is 10 to 200 sccm; in S3, the temperature is controlled at 2-10 ℃ per minute^-1The temperature is raised at the temperature raising rate of (1).

10. The application of the nickel phosphide compound as claimed in any one of claims 1 to 4 in the aspect of electrocatalytic decomposition of water to produce hydrogen under the condition of full pH.

Technical Field

The invention belongs to the technical field of electrocatalysis materials, and particularly relates to a nickel phosphide compound with a multi-level hole structure, and a preparation method and application thereof.

Technical Field

With the progress of human society, the demand of social development on energy is increasing day by day. At present, traditional fossil energy such as petroleum, coal, natural gas and the like are still main energy sources relied on for human survival. Due to the large amount of use, the fossil energy is increasingly exhausted, and meanwhile, serious environmental pollution is brought, so that the fossil energy becomes a bottleneck restricting the sustainable development of human society. The development of green renewable energy sources capable of replacing traditional fossil energy sources becomes a key for solving the dual challenges of energy and environmental problems and promoting the sustainable development of the human society.

Hydrogen energy (hydrogen gas) is an ideal high-quality clean energy, has the advantages of abundant reserves, wide sources, high energy density and the like, and is known as a secondary energy with the most development prospect in the 21 st century. The hydrogen energy plays an important role in solving the problems of energy crisis, global warming, environmental pollution and the like, and becomes a strategic choice for optimizing the energy consumption structure and guaranteeing the national energy supply safety in China. Currently, hydrogen is produced primarily by steam reforming of methane, a process that not only produces large quantities of carbon dioxide, but also consumes non-renewable fossil fuels. In contrast, electrocatalytic decomposition of water to produce hydrogen represents a clean, sustainable hydrogen production process.

Theoretically, only 1.23V is needed for electrocatalytic decomposition of water. In practical application, due to the existence of system ohmic resistance, solution resistance and charge transfer resistance and the high hydrogen evolution/oxygen evolution overpotential of the catalyst, the voltage which needs to be loaded on an electrolytic cell actually reaches 1.8-2V, and the wide application of hydrogen production by electrolytic water is greatly limited (the hydrogen production by electrolytic water can only meet the global 4% hydrogen demand). In order to reduce the external electric energy for hydrogen production by water electrolysis and improve the efficiency of water decomposition by electrocatalysis, besides optimizing the structure of the electrolytic cell, an electrocatalyst with high-efficiency hydrogen production efficiency needs to be developed. Currently, noble platinum-based metals remain the best hydrogen evolution electrocatalysts (low hydrogen evolution overpotential, high current density, excellent stability), but their scarcity and high cost limit their application in water electrolysis. The development of a non-platinum-based electrocatalyst with high hydrogen evolution performance, low cost and wide pH application range is an important premise for wide application of electrocatalytic decomposition of water to prepare hydrogen and is a hot problem at the front of current research.

Disclosure of Invention

The invention aims to overcome the defects or shortcomings of scarcity and high cost of platinum-based noble metal serving as a hydrogen evolution electrocatalyst in the prior art, and provides a nickel phosphide compound with a multi-layer pore structure. The nickel phosphide compound provided by the invention has a multi-level hole structure, wherein the through macropores are beneficial to the transfer of electrolyte and gas diffusion, and the macropores and the nano holes are beneficial to exposing more active sites, increasing the contact with the electrolyte and accelerating the reaction rate. The nickel phosphide compound with the multi-layer hole structure can be used as a working electrode for electrochemically decomposing water to produce hydrogen, shows excellent hydrogen evolution performance under full pH, and has the advantages of low cost, excellent electro-catalytic hydrogen evolution performance and strong stability.

The invention also aims to provide a preparation method of the nickel phosphide composite with the multi-level hole structure.

The invention also aims to provide application of the nickel phosphide composite with the multi-level hole structure.

In order to realize the purpose of the invention, the invention adopts the following scheme:

a nickel phosphide compound with a multi-level hole structure comprises a metal foam framework and nickel phosphide compound micron sheets covered on the surface of the metal foam framework; penetrating macropores with the average pore diameter of 50-500 mu m are distributed among the metal foam frameworks, and macropores with the average pore diameter of 10-100 mu m are distributed on the surfaces of the metal foam frameworks; nanometer holes are distributed on the nickel phosphide compound micron sheet.

The nickel phosphide compound provided by the invention has a multi-level hole structure, wherein the through macropores are beneficial to the transfer of electrolyte and gas diffusion, and the macropores and the nano holes are beneficial to exposing more active sites, increasing the contact with the electrolyte and accelerating the reaction rate. The nickel phosphide compound with the multi-level hole structure can be used as a working electrode for electrochemically decomposing water to produce hydrogen, and shows excellent hydrogen evolution performance under full pH.

The application method comprises the following steps: 0.5-2 mol/L potassium hydroxide aqueous solution, 0.1-1 mol/L sulfuric acid aqueous solution and 0.05-0.2 mol/L phosphate buffer solution are respectively used as alkaline, acidic and neutral electrolytes, the nickel phosphide compound with the multi-layer pore structure is used as a working electrode, a corrected saturated calomel electrode is used as a reference electrode, a graphite rod electrode is used as a counter electrode, the test pressure is normal pressure, the test temperature is room temperature, high-purity hydrogen is blown into the electrolyte for half an hour before the electrochemical performance test, and the hydrogen is kept blown in the whole test process; only-92 mV, -154mV and-132 mV are needed respectively to realize-10 mA cm in acid electrolyte, alkaline electrolyte and neutral electrolyte^-2And no significant decay in the stability test for a total of 20 hours.

Metal foam skeletons conventional in the art can be used in the present invention and are commercially available. The average pore diameter can be selected within 50-500 μm, and the electrolyte transfer and gas diffusion can be realized.

Nickel phosphide compositions conventional in the art can be used in the present invention, e.g., Ni₂P、Ni₁₂P₅、NiP₂、Ni₅P₄And the like.

Preferably, the large pores are formed by metal plating.

Electroplatable metals conventional in the art can be formed to electroplate the macropores described herein, such as nickel, copper, cobalt, iron, zinc, and the like.

The nickel phosphide compound with the multi-level hole structure has a metal foam framework-metal plating layer-nickel phosphide compound micron sheet structure.

The nickel phosphide compound micron-sheet structure is distributed on the surfaces (including the outer surface and the pore surface) of the metal foam framework and the metal coating, and nano-pores are distributed on the surface of the phosphide compound micron-sheet.

Preferably, the nickel phosphide compound micron sheet is made of Ni₂P and Ni₁₂P₅And (4) forming.

Preferably, the aperture of the nano-pores is 60-600 nm.

The preparation method of the nickel phosphide compound comprises the following steps:

s1: the metal foam is subjected to constant current treatment to deposit metal on the surface of the metal foam and form macropores, and the current density of the constant current treatment is-0.5A-cm^-2～-2A·cm^-2The treatment time is 100-1000 s;

s2: immersing the metal foam obtained in the step S1 into a mixed solution of a nickel source and organic amine, carrying out hydrothermal reaction at the temperature of 80-120 ℃ for 1-10 h, washing and drying;

s3: and (4) mixing the metal foam obtained in the step (S2) with a phosphorus source, and keeping the temperature at 250-400 ℃ for 0.5-4 h to obtain the nickel phosphide compound.

The S1 step is to deposit metal and form a large pore by electrochemical deposition. At a current density of-0.5A · cm^-2～-2A·cm^-2The thickness of the deposited metal is generally 500-1600 mu m under the condition of 100-1000 s, and the deposited metal forms macropores with the aperture of 10-100 mu m on the metal foam framework. Specifically, in the constant current process, the current I ═ j × Area, where j is the current density and Area is the Area of the working electrode metal foam.

And step S2, nickel hydroxide is obtained through hydrothermal reaction.

And step S3, calcining the nickel hydroxide and the phosphorus source to obtain the nickel phosphide compound micron sheet.

The preparation method provided by the invention has the advantages of cheap and easily available raw materials, simple process, short preparation period and high repeatability, and is suitable for mass preparation.

Preferably, the metal foam in S1 further comprises ultrasonic treatment before the constant current treatment.

Sonication as is conventional in the art may be used in the present invention.

More preferably, the metal foam is sequentially and respectively ultrasonically cleaned for 10 minutes by using 1mol/L hydrochloric acid, deionized water and absolute ethyl alcohol.

S1 may select a corresponding electrolyte and electrode according to the deposited metal. For example, when depositing nickel metal, a mixed solution of nickel chloride and ammonium chloride can be used as an electrolyte, specifically 0.05-0.3 mol/L nickel chloride and 0.5-3 mmol/L ammonium chloride; nickel sheets can be selected as a counter electrode and a reference electrode (nickel foam is a working electrode); when copper metal is deposited, a mixed solution of copper sulfate and sulfuric acid is selected as an electrolyte, specifically 0.5-1 mol/L copper sulfate and 0.05-0.1 mol/L sulfuric acid, copper foam is selected as a working electrode, and copper sheets are selected as a counter electrode and a reference electrode.

Both nickel sources and organic amines conventionally used in the art for hydrothermal reaction to form nickel hydroxide may be used in the present invention, and concentration control may also be selected according to conventional control conditions.

Preferably, the nickel source in S2 is one or more of nickel nitrate, nickel sulfate and nickel chloride; the organic amine source is one or more of hexamethylenetetramine, diethylenetriamine or triethylenediamine.

Preferably, the concentration of the nickel source in S2 is 0.1-0.2 mol/L; the concentration of the organic amine source is 0.2-0.4 mol/L in terms of amino.

Preferably, the phosphorus source in S3 is one or more of sodium hypophosphite or red phosphorus.

Preferably, the reaction in S3 is performed under an inert atmosphere, and the flow rate of the inert gas is 10-200 sccm.

More preferably, the inert atmosphere is argon.

Preferably, the temperature of S3 is 2-10 ℃ min^-1The temperature is raised at the temperature raising rate of (1).

The application of the nickel phosphide compound in the aspect of electrocatalytic decomposition of water to produce hydrogen under the condition of full pH is also within the protection scope of the invention.

Compared with the prior art, the invention has the following beneficial effects:

the nickel phosphide compound provided by the invention has a multi-level hole structure, wherein the through macropores are beneficial to the transfer of electrolyte and gas diffusion, and the macropores and the nano holes are beneficial to exposing more active sites, increasing the contact with the electrolyte and accelerating the reaction rate. The nickel phosphide compound with the multi-level hole structure can be used as a working electrode for electrochemically decomposing water to produce hydrogen, and shows excellent hydrogen evolution performance under full pH.

The preparation method provided by the invention has the advantages of cheap and easily available raw materials, simple process, short preparation period and high repeatability, and is suitable for mass preparation.

Drawings

FIG. 1 is an X-ray diffraction diagram of a nickel phosphide composite with a multi-level hole structure provided in example 1 of the present invention;

FIG. 2 is a scanning electron microscope image of a nickel phosphide composite with a multi-level hole structure provided in example 1 of the present invention;

FIG. 3 is a linear sweep voltammogram for hydrogen evolution in alkaline, acidic and neutral electrolytes of a nickel phosphide composite with a multi-level pore structure provided in example 1 of the present invention;

fig. 4 is a graph illustrating the potentiostatic stability test of the nickel phosphide composite with the multi-level pore structure in alkaline, acidic and neutral electrolytes provided in example 1 of the present invention.

Detailed Description

The invention is further illustrated by the following examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. Experimental procedures without specific conditions noted in the examples below, generally according to conditions conventional in the art or as suggested by the manufacturer; the raw materials, reagents and the like used are, unless otherwise specified, those commercially available from the conventional markets and the like. Any insubstantial changes and substitutions made by those skilled in the art based on the present invention are intended to be covered by the claims.