CN114293222A - Synthesis method of ultrafine ruthenium diphosphide nanoparticle electrocatalyst - Google Patents

Abstract

The invention discloses a superfine ruthenium diphosphide (RuP)₂) A preparation method of a nano-particle electrocatalyst and application thereof in Hydrogen Evolution Reaction (HER). The invention prepares the highly dispersed superfine RuP embedded in N, P, S co-doped carbon nano-tube by a coordination confinement strategy₂Nanoparticles (RuP)₂@NPS‑CNT）。RuP₂The @ NPS-CNT catalyst exhibits excellent HER electrocatalytic performance, driving 10, 100 and 300 mA cm in 1.0M KOH with overpotentials of only 10, 83 and 158 mV, respectively^‑2The current density of (1). Tafel slope of only 22 mV decade^‑1。RuP₂The catalytic activity of the @ NPS-CNT is superior to that of a commercial Pt/C catalyst, and the catalyst is low in preparation cost, wide in raw material source and has potential commercial value.

Description

Synthesis method of ultrafine ruthenium diphosphide nanoparticle electrocatalyst

Technical Field

The invention relates to the field of inorganic synthesis and energy catalysis, in particular to ultrafine ruthenium diphosphide (RuP)₂) A controlled synthesis method of nano particles and application thereof as an electrocatalytic hydrogen evolution reaction.

Background

The increasingly depleted fossil fuels and severe environmental concerns have prompted the search for sustainable clean energy. Hydrogen (H)₂) Not only has high energy density, but also has no pollution to combustion products, and is an ideal substitute for fossil fuel. Electrolytic water is considered one of the most promising ways to capture hydrogen energy on a large scale. To efficiently produce H₂Development of a Hydrogen Evolution Reaction (HER) electrocatalyst with high activity and high stability is of great importance. Currently, Pt-based materials are considered to be the most advanced HER electrocatalysts. However, high cost and rarity have been the biggest obstacles to its large-scale industrialization. Therefore, it is very important to vigorously develop more economical and practical electrocatalysts having platinum-like activity.

The HER catalysts reported at present are mainly transition metals such as simple substances, alloys, chalcogenides, phosphides, nitrides, carbides, borides, etc. Among them, transition metal phosphide is a very promising catalyst. However, the catalytic activity of these non-noble metal-based phosphides compared to Pt is still unsatisfactory. Ruthenium is the cheapest Pt group element and has a much lower market price than Pt, so Ru-based materials are receiving wide attention as potential HER catalysts. Recently, Ru-based phosphides have been demonstrated to have better HER catalytic activity than non-noble metal-based phosphides. Although Ru-based phosphide has significant HER activity, metal phosphide is easily agglomerated to form large nanoparticles during high-temperature phosphating preparation, resulting in a significant reduction in its catalytically active sites. It remains a challenge to synthesize highly dispersed ultrafine Ru-based phosphide nanoparticles so as to expose abundant active sites.

Disclosure of Invention

The invention aims to provide a synthesis method of ultrafine ruthenium diphosphide nanoparticles to prepare a Ru-based electrocatalyst with excellent catalytic activity.

In order to achieve the purpose, the invention adopts the following technical scheme.

In one aspect, the present invention provides an ultrafine ruthenium diphosphide nanoparticle electrocatalyst (RuP)₂@ NPS-CNT catalyst), the specific steps are as follows:

1) adding carbon nano tube (50-200 mg) and ruthenium salt (20-100 mg) into ultra-dry methanol (80 mL), and performing ultrasonic dispersion to prepare solution A;

2) dissolving hexachlorotriphosphazene and 4,4' -dihydroxy diphenyl sulfone in the molar ratio of 2:3 in 20 mL of ultra-dry methanol to prepare a solution B; adding the solution B into the 80 mL solution A to prepare a solution C;

3) dripping 1-2 mL of triethylamine into the solution C, stirring at room temperature for 1-2 days, performing suction filtration by using an organic polymer membrane, washing with common methanol for three times, and naturally drying to obtain a Ru-PZS @ CNT precursor;

4) placing the Ru-PZS @ CNT precursor powder obtained in the step 3) into a porcelain boat, placing the porcelain boat in a tube furnace, heating the tube furnace to 800-₂@ NPS-CNT catalyst.

Further, in the step 1), the ruthenium salt is ruthenium nitrate salt, ruthenium acetate salt, ruthenium acetylacetonate salt or ruthenium chloride salt.

Further, the ruthenium salt is ruthenium trichloride (RuCl)₃）。

In another aspect, the present invention provides an ultrafine ruthenium diphosphide nanoparticle electrocatalyst (RuP) prepared according to the above synthesis method₂@ NPS-CNT catalyst), the average particle diameter of the ruthenium diphosphide nanoparticle electrocatalyst is 3.0 nm, and the specific surface area of the catalyst is 214 m² g^-1。

RuP prepared by the above method of the present invention₂The @ NPS-CNT catalyst can be applied as a cathode catalyst in an electrocatalytic hydrogen evolution reaction.

RuP as reported at present₂The nanoparticles are generally larger than 5 nm in size and have an undesirable degree of dispersion, which significantly reduces RuP₂The catalyst is electrocatalytic active. The PZS polymer formed by polymerizing organic monomers of hexachlorotriphosphazene and 4,4' -dihydroxydiphenylsulfone contains rich N atoms and Ru³⁺Ion coordination can effectively reduce the diffusion and agglomeration of metal in the pyrolysis process, thereby preparing the superfine RuP₂Nanoparticles.In addition, PZS polymers also contain abundant P atoms and are therefore pyrogenically prepared RuP₂The process does not require the introduction of an additional P source. Compared with the prior art, the strategy effectively reduces toxic PH in the P-type process₃The release of large amounts of gas and the excessive waste of P resources.

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

(1) the coordination confinement strategy used by the invention can prepare superfine RuP with the grain diameter of 3.0 nm₂Nanoparticles;

(2) preparation RuP of the invention₂No additional P source is needed to be introduced, and the toxic PH in the P conversion process is effectively reduced₃Large release of gas and excessive waste of P resources;

(3) RuP prepared by the invention₂@ NPS-CNT catalyst requires only 10, 83 and 158 mV overpotentials in 1.0M KOH, respectively, to drive 10, 100 and 300 mA cm^-2The current density of (1) is such that the Tafel slope is only 22 mV decade^-1The catalytic activity is superior to that of the commercial Pt/C catalyst.

Drawings

FIG. 1 shows an embodiment RuP of the present invention₂X-ray powder diffraction pattern of @ NPS-CNT.

FIG. 2 shows an embodiment RuP of the present invention₂Scanning electron microscopy of @ NPS-CNT.

FIG. 3 illustrates an embodiment RuP of the present invention₂Transmission electron microscopy images of @ NPS-CNT.

FIG. 4 shows an embodiment RuP of the present invention₂Raman spectrum of @ NPS-CNT.

FIG. 5 shows an embodiment RuP of the present invention₂The nitrogen adsorption diagram of @ NPS-CNT.

FIG. 6 shows an embodiment RuP of the present invention₂Linear sweep voltammetry profiles of @ NPS-CNT and commercial Pt/C.

FIG. 7 shows an embodiment RuP of the present invention₂The Tafel plot of @ NPS-CNT and commercial Pt/C.

FIG. 8 shows an embodiment RuP of the present invention₂Constant potential electrolysis diagram of @ NPS-CNT.

FIG. 9 shows an embodiment RuP of the present invention₂@ NPS-CNT Linear sweep voltammetry profiles before and after 10000 CV cycles.

FIG. 10 shows the present inventionRuP₂@ NPS-CNT and commercial Pt/C electrochemical impedance spectroscopy.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited to the specific embodiments disclosed below.

Example 1 RuP₂Preparation of @ NPS-CNT catalyst

100 mg of carbon nanotubes (outer diameter: 15 nm, length: 50 μm) and RuCl (ruthenium trichloride)₃(0.2 mmol) is added into 80 mL of ultra-dry methanol, and the solution A is prepared after ultrasonic treatment for 1 h. 300 mg of hexachlorotriphosphazene and 675 mg of 4,4' -dihydroxydiphenylsulfone were dissolved in 20 mL of ultra-dry methanol to prepare a solution B, and the solution B was added to the above 80 mLA solution and stirred at room temperature for 10 min to prepare a solution C. And then 1 mL of triethylamine is dripped into the solution C, stirred for 24 h at room temperature, filtered by an organic polymer membrane, washed by common methanol for three times, and naturally dried to obtain the Ru-PZS @ CNT precursor. The resulting Ru-PZS @ CNT precursor powder was then placed in a porcelain boat and placed in a tube furnace. The tube furnace was heated to 800 ℃ under Ar gas flow at a ramp rate of 5 ℃/min and held at 800 ℃ for 2 hours. Naturally cooling to obtain RuP₂@ NPS-CNT catalyst. The X-ray diffraction pattern of the product obtained in this example is shown in FIG. 1; FIG. 2 shows a scanning electron microscope; FIG. 3 is a transmission electron microscope image; the Raman spectrum is shown in FIG. 4; the nitrogen adsorption pattern is shown in FIG. 5.

Example 2 RuP obtained in example 1₂Electrocatalytic HER activity test of @ NPS-CNT

RuP from example 1₂The electrocatalytic HER performance test of @ NPS-CNT was performed on the CHI760E electrochemical workstation. The electrolyte was 1.0M KOH aqueous solution. Glassy carbon electrodes, Ag/AgCl and graphite rods were used as working, reference and counter electrodes, respectively. The linear sweep voltammetry curve shown in FIG. 6 is a sweep at 5.0 mV/sObtained at high speed, RuP shown in FIG. 6₂@ NPS-CNT drives 10, 100 and 300 mA cm^-2The overpotentials required for the current densities were 10, 83 and 158 mV, respectively, with a catalytic activity significantly better than commercial Pt/C. The Tafel plot shown in FIG. 7 was obtained by calculation from FIG. 6, and is known as RuP₂The tafel slope of @ NPS-CNT is 22 mV dec^-1Much lower than commercial Pt/C.

Example 3 RuP from example 1₂Electrochemical stability test of @ NPS-CNT

FIG. 8 shows a potentiostatic electrolysis diagram with individual control RuP₂@ NPS-CNT was obtained by electrolysis at overpotentials of 10, 83 and 158 mV for 25 h, from which RuP was seen₂The @ NPS-CNT maintains good catalytic stability at different current densities. RuP shown in FIG. 9₂Linear sweep voltammetry curves before and after @ NPS-CNT sweep of 10000 CV cycles, with two lines substantially coincident RuP₂The @ NPS-CNT catalyst has good catalytic stability.

Example 4 RuP obtained in example 1₂@ NPS-CNT electrochemical impedance spectroscopy test

Electrochemical Impedance Spectroscopy (EIS) measurements were made in the frequency range of 0.01 Hz to 100 kHz. The electrochemical impedance spectrum is shown in FIG. 10, explanation RuP₂The @ NPS-CNT catalyst has good conductivity.

In conclusion, the invention prepares the highly dispersed superfine RuP embedded in N, P, S co-doped carbon nano-tube by a coordination confinement strategy₂Nanoparticles (RuP)₂@ NPS-CNT). First, Ru-PZS @ CNT with a core-shell structure is formed by polymerization of hexachlorotriphosphazene and 4,4 '-dihydroxydiphenylsulfone on the surface of a carbon nanotube (PZS: poly (cyclotriphosphazene-co-4, 4' -sulfonyldiphenol)). Subsequently, RuP was prepared by pyrolyzing Ru-PZS @ CNT in an argon atmosphere₂@ NPS-CNT catalyst. Because the PZS polymer contains abundant N atoms which can coordinate with metal ions, the diffusion and agglomeration of metals in the pyrolysis process can be effectively reduced. Thus, RuP was prepared₂The average particle size of the nanoparticles was about 3.0 nm. RuP₂The @ NPS-CNT catalyst exhibits excellent HER electrocatalytic performance, driving 10, 100 and 300 mA cm in 1.0M KOH with overpotentials of only 10, 83 and 158 mV, respectively^-2The current density of (1). Tafel slope of only 22 mV decade^-1。RuP₂The catalyst activity of the @ NPS-CNT catalyst is superior to that of a commercial Pt/C catalyst, and the catalyst has a commercial prospect. The excellent catalytic activity is attributed to the following three aspects: (1) highly dispersed ultrafine RuP₂The nano particles can expose abundant catalytic active sites; (2) n, P, S heteroatom doped carbon can not only optimize hydrogen adsorption energy and thus raise the intrinsic activity of electrocatalyst, but also stabilize superfine RuP₂A nanoparticle; (3) the specific one-dimensional nano structure can further improve the conductivity and the specific surface area of the catalyst.

Claims (7)

1. A synthesis method of a superfine ruthenium diphosphide nanoparticle electrocatalyst is characterized by comprising the following steps:

1) adding 50-200 mg of carbon nano tube and 20-100 mg of ruthenium salt into 80 mL of ultra-dry methanol solvent, and uniformly mixing to prepare solution A;

2) dissolving hexachlorotriphosphazene and 4,4' -dihydroxy diphenyl sulfone in the molar ratio of 2:3 in 20 mL of ultra-dry methanol to prepare a solution B; adding the solution B into the solution A to prepare solution C;

3) adding 1-2 mL of triethylamine into the solution C to react to obtain a Ru-loaded polymer and carbon nanotube composite precursor Ru-PZS @ CNT;

4) the Ru-PZS @ CNT powder is pyrolyzed at high temperature to obtain RuP₂@ NPS-CNT catalyst.

2. The method for synthesizing the ultrafine ruthenium diphosphide nanoparticle electrocatalyst according to claim 1, wherein the step 3) of preparing the Ru-PZS @ CNT precursor comprises the specific steps of dropwise adding 1-2 mL of triethylamine into the C solution, confining Ru atoms or ions in a polymer skeleton during the reaction, stirring at room temperature for 1-2 days, performing suction filtration with an organic polymer membrane, washing with common methanol for three times, and naturally drying to obtain the Ru-PZS @ CNT precursor.

3. The method for synthesizing the ultrafine ruthenium diphosphinate nanoparticle electrocatalyst according to claim 1, wherein in step 1), the ruthenium salt is ruthenium nitrate salt, ruthenium acetate salt, ruthenium acetylacetonate salt or ruthenium chloride salt.

4. The method for synthesizing the ultrafine ruthenium phosphide nanoparticle electrocatalyst according to claim 1, wherein in the step 4), the pyrolysis condition is argon or nitrogen atmosphere, and the pyrolysis temperature is 800-.

5. An ultrafine ruthenium diphosphide nanoparticle electrocatalyst which is characterized by being prepared according to the synthesis method of any one of claims 1 to 4; the average particle diameter of the ruthenium diphosphide nano particles is 3.0 nm, and the specific surface area of the catalyst reaches 214 m² g^-1。

6. RuP according to claim 5₂The application of the @ NPS-CNT catalyst in the field of energy catalysis is characterized by being capable of being applied to water decomposition reaction, carbon dioxide reduction reaction, oxygen reduction reaction or organic catalysis reaction.

7. RuP according to claim 5₂The application of the @ NPS-CNT catalyst in the electrolytic water hydrogen evolution reaction is characterized in that the catalyst is used as a cathode catalyst.

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