阅读说明：本技术 一种双金属钴钌-氮磷掺杂多孔碳电催化剂及其制备方法与应用 (Bimetallic cobalt ruthenium-nitrogen phosphorus doped porous carbon electrocatalyst and preparation method and application thereof ) 是由 彭新文 曾小燕 杜帆 于 2019-07-18 设计创作，主要内容包括：本发明公开了一种双金属钴钌-氮磷掺杂多孔碳电催化剂及其制备方法与应用。所述催化剂的制备方法为：利用磷酸化的壳聚糖气凝胶与金属钴盐进行螯合配位后,加入微量的金属钌盐,加热蒸干后碳化得到含金属钴和钌的氮磷掺杂多孔碳材料。本发明以廉价且可再生、可降解的壳聚糖作为碳基底材料,反应条件简单,易于操作,制备的催化剂应用于电解水析氢反应,具有催化活性高和稳定性好等优点,为生物质碳材料在电催化以及能源领域提供了广阔的应用前景。(The invention discloses a bimetallic cobalt ruthenium-nitrogen phosphorus doped porous carbon electrocatalyst and a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: carrying out chelating coordination on phosphorylated chitosan aerogel and metal cobalt salt, adding a trace amount of metal ruthenium salt, heating, evaporating to dryness, and carbonizing to obtain the nitrogen-phosphorus doped porous carbon material containing metal cobalt and ruthenium. The invention takes cheap, renewable and degradable chitosan as the carbon substrate material, has simple reaction conditions and easy operation, and the prepared catalyst is applied to the electrolytic water hydrogen evolution reaction, has the advantages of high catalytic activity, good stability and the like, and provides wide application prospect for the biomass carbon material in the fields of electro-catalysis and energy.)

1. A preparation method of a bimetallic cobalt ruthenium-nitrogen phosphorus doped porous carbon electrocatalyst is characterized by comprising the following steps:

(1) Dissolving chitosan in an acid solution, adding phosphoric acid, stirring uniformly, adding formaldehyde, reacting for 8-12 h at 60-90 ℃, cooling to room temperature, dialyzing, and freeze-drying to obtain a phosphorylated chitosan aerogel;

(2) Phosphorylating chitosan aerogel and Co (NO)₃)₂·6H₂And adding O into water, heating to dissolve, dropwise adding a ruthenium chloride solution, dropwise adding within 5-20 min, heating to evaporate the solvent, carbonizing the obtained solid product in a nitrogen or inert gas environment, grinding, acid washing, suction filtering and drying to obtain the CoRu @ NPC electrocatalyst.

2. The preparation method of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst as claimed in claim 1, wherein the Co (NO) in step (2)₃)₂·6H₂The molar ratio of the O to the ruthenium chloride in the ruthenium chloride solution is 1: (0.2 to 0.4); the phosphorylated chitosan aerogel and Co (NO)₃)₂·6H₂The mass ratio of O is (1.72-6.88): 1.

3. the preparation method of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst according to claim 1 or 2, wherein the carbonization treatment temperature is 700-900 ℃, and the carbonization time is 1-4 h.

4. the preparation method of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst according to claim 3, wherein the mass concentration of the chitosan in the step (1) in the acid solution is 5.9-17.9 g/L; the molar ratio of the mass of the chitosan to the phosphoric acid is (0.1-1.79) g: (1-20) mmol; the molar ratio of the phosphoric acid to the formaldehyde is 1: (0.5-2).

5. The preparation method of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst, according to claim 4, characterized in that the acid solution in the step (1) is an acetic acid solution with a volume concentration of 1-4%; the phosphoric acid is added in the form of a phosphoric acid solution, wherein the concentration of the phosphoric acid solution is 1-4 mmol/L.

6. The preparation method of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst, according to claim 4, is characterized in that the mass concentration of the phosphorylated chitosan aerogel in the step (2) in water is 1-20 g/L; the concentration of the ruthenium chloride solution is 2-6 mmol/L; the temperature for heating and evaporating the solvent is 60-90 ℃.

7. The preparation method of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst, according to claim 4, is characterized in that the dialysis time in the step (1) is 24-60 h; the temperature of the freeze drying is-50 to-20 ℃, and the time is 2 to 4 days;

The heating and dissolving temperature in the step (2) is 50-80 ℃; the grinding time is 5-20 min; the acid reagent used for acid washing is a hydrochloric acid solution with the concentration of 0.5-2 mol/L; the pickling time is 5-10 h; the drying temperature is 50-80 ℃.

8. The bimetallic cobalt ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst prepared by the method of any one of claims 1 to 7.

9. The application of the bimetallic cobalt ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst in the catalytic electrolysis hydrogen evolution reaction is characterized in that the pH of an electrolyte solution in the electrolysis hydrogen evolution reaction is 0-14.

10. The application of the bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst in the catalytic electrolysis hydrogen evolution reaction according to claim 9, wherein the electrolyte solution is H with the concentration of (0.5-2) mol/L₂SO₄The solution, KOH solution with the concentration of (0.1-2) mol/L or PBS buffer solution with the concentration of (1-4) mol/L.

Technical Field

The invention belongs to the field of catalytic material technology and energy storage, and particularly relates to a bimetallic cobalt-ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst, and a preparation method and application thereof.

Background

With the use of fossil fuels in large quantities, the problems of environmental pollution and energy exhaustion become more and more serious, and the development of clean and green energy is more and more emphasized. Hydrogen energy is used as an energy carrier, the calorific value generated by combustion is high, and combustion products do not cause pollution to the environment, so that the hydrogen energy is widely promoted as a substitute of fossil fuels. Compared with methods of hydrogen production by reforming natural gas, hydrogen production by solar energy, hydrogen production by biomass and the like, the method for producing hydrogen by electrolyzing water has the advantages of high hydrogen production purity, no pollution, simple hydrogen production equipment and the like, and is a sustainable hydrogen production way. However, in large-scale practical production, an efficient and stable catalyst is essential for accelerating the water electrolysis process, so that research and preparation of the water electrolysis catalyst for improving the reaction efficiency are of great significance for development and popularization of hydrogen energy.

in recent years, biomass raw materials have attracted more and more attention for their strong renewability, wide sources, and easy chemical modification. Chitosan is a second-most abundant biopolymer chitin derivative in nature, has more abundant functions than chitin, and has important application in many fields such as food, medicine, chemical industry, biology, textile and the like. The chitosan has rich carbon content and strong conductivity, can be used as a conductive material, and has strong complexation effect, and-NH on the carbon chain₂The group can form a complex with metal ions to prepare multifunctional biomass-based materials. The carbon material prepared by using chitosan as a raw material not only can increase the electrochemical active area between the catalyst and the electrolyte by surface pore-forming, but also can improve the electronic conductivity, the surface wettability and the like of the catalyst by doping nitrogen, phosphorus, sulfur and other heteroatoms, which are beneficial to improving the catalytic reaction activity.

At present, the noble metal platinum-based catalyst has the best effect of catalyzing water electrolysis to produce hydrogen, has nearly zero overpotential and better stability, but has very limited platinum reserve and high cost, and restricts the large-scale popularization of the platinum in industry. In order to prepare a catalyst with low price and high and stable performance, research and preparation of a carbon material catalyst without precious metals are started at home, and various catalyst products with good effects are obtained by doping metal sulfides, metal selenides, metal phosphides and heteroatoms, but a non-precious metal catalyst is easy to be corroded by acid, has higher overpotential and lower stability, and has inferior overall performance to a platinum-based catalyst. Therefore, overcoming the limitations of non-noble metals in electrocatalytic performance is a difficult problem in preparing high-efficiency catalysts. At present, alloying a small amount of noble metal and transition metal is an important way for improving the electrocatalytic performance of the transition metal.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention mainly aims to provide a preparation method of a bimetallic cobalt ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst. According to the method, chitosan is used as a biomass carbon-based material, common transition metal cobalt and cheap noble metal ruthenium are introduced, and a metal cobalt ruthenium-nitrogen phosphorus doped porous carbon (CoRu @ NPC) electrocatalyst is prepared by a two-step method.

The invention also aims to provide the bimetallic cobalt ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst prepared by the method.

The invention further aims to provide application of the bimetallic cobalt ruthenium-nitrogen-phosphorus doped porous carbon electrocatalyst in catalyzing electrolysis water hydrogen evolution reaction.

The purpose of the invention is realized by the following technical scheme:

A preparation method of a bimetallic cobalt ruthenium-nitrogen phosphorus doped porous carbon (CoRu @ NPC) electrocatalyst comprises the following steps:

(1) Dissolving chitosan in an acid solution, adding phosphoric acid, stirring uniformly, adding formaldehyde, reacting for 8-12 h at 60-90 ℃, cooling to room temperature, dialyzing, and freeze-drying to obtain phosphorylated chitosan aerogel (P-CS);

(2) Phosphorylating chitosan aerogel and Co (NO)₃)₂·6H₂Adding O into water, heating for dissolving, dropwise adding a ruthenium chloride solution, dropwise adding within 5-20 min, heating for evaporating the solvent, carbonizing the obtained solid product in a nitrogen or inert gas environment, grinding, acid washing, pumpingAnd filtering and drying to obtain the CoRu @ NPC electrocatalyst.

The mass concentration of the chitosan in the acid solution in the step (1) is 5.9-17.9 g/L, and the acid solution is an acetic acid solution with the volume concentration of 1-4%.

The molar ratio of the mass of the chitosan to the phosphoric acid in the step (1) is (0.1-1.79) g: (1-20) mmol; the molar ratio of the phosphoric acid to the formaldehyde is 1: (0.5-2).

adding phosphoric acid in the step (1) in the form of a phosphoric acid solution, wherein the concentration of the phosphoric acid solution is 1-4 mmol/L, and the solvent is water.

The dialysis time in the step (1) is 24-60 hours, and the dialysate for dialysis is ultrapure water; the temperature of the freeze drying is-50 to-20 ℃, and the time is 2 to 4 days.

Phosphorylated chitosan aerogel and Co (NO) in step (2)₃)₂·6H₂The mass ratio of O is (1.72-6.88): 1.

The mass concentration of the phosphorylated chitosan aerogel in the step (2) in water is 1-20 g/L, and preferably 10 g/L.

Heating and dissolving at 50-80 ℃ in the step (2) to ensure that the phosphorylated chitosan aerogel and Co (NO) are heated₃)₂·6H₂O was completely dissolved in water.

Co (NO) in step (2)₃)₂·6H₂The molar ratio of the O to the ruthenium chloride in the ruthenium chloride solution is 1: (0.2 to 0.4); the concentration of the ruthenium chloride solution is 2-6 mmol/L.

And (3) the solvent of the ruthenium chloride solution in the step (2) is water.

And (3) heating to evaporate the solvent in the step (2) to be 60-90 ℃.

The carbonization treatment in the step (2) is carried out in a tube furnace; the temperature of the carbonization treatment is 700-900 ℃, and the carbonization time is 1-4 h. The carbonization heating rate is 2-8 ℃/min.

And (3) grinding for 5-20 min in the step (2).

And (3) the acid reagent used in the acid washing in the step (2) is a hydrochloric acid solution with the concentration of 0.5-2 mol/L, and the acid washing time is 5-10 h.

And (3) drying at the temperature of 50-80 ℃ to constant weight in the step (2).

The bimetallic cobalt ruthenium-nitrogen-phosphorus doped porous carbon (CoRu @ NPC) electrocatalyst prepared by the method.

The bimetallic cobalt ruthenium-nitrogen phosphorus doped porous carbon (CoRu @ NPC) electrocatalyst is a nano material.

The bimetallic cobalt ruthenium-nitrogen phosphorus doped porous carbon (CoRu @ NPC) electrocatalyst is applied to the catalysis of the electrolysis water hydrogen evolution reaction.

The pH value of the electrolyte solution for the electrolytic water hydrogen evolution reaction is 0-14. The electrolyte solution is preferably H with the concentration of (0.5-2) mol/L₂SO₄The solution, KOH solution with the concentration of (0.1-2) mol/L or PBS buffer solution with the concentration of (1-4) mol/L.

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

(1) the invention takes cheap and abundant chitosan as the biomass carbon substrate material, and a large amount of-NH is arranged on the carbon chain of the chitosan₂The group is easy to modify and form a metal complex, is a main source of an electrocatalytic active site, and simultaneously realizes high-value utilization of the biomass material.

(2) The invention takes phosphorylated chitosan as a coordination agent and a carbon source to react with Co²⁺Introducing a very small amount of Ru after successful coordination³⁺and (3) obtaining uniform powder by co-thermal evaporation of the solvent, and carrying out high-temperature carbonization to obtain the catalytic material simultaneously loading metal cobalt and ruthenium on the nitrogen-phosphorus co-doped porous carbon. The carbon layer electron cloud distribution is changed by the synergistic effect of the cobalt and the ruthenium and the heteroatom co-doping effect, so that a large number of active sites are provided, and conditions are created for improving the hydrogen evolution capacity of the electrolyzed water. The catalytic material has good performance in hydrogen evolution performance of electrolyzed water under acidic, neutral and alkaline conditions, and is suitable for the fields of electrolyzed water catalytic conversion, energy development, electrode materials and the like.

(3) The invention takes cheap noble metal ruthenium as main catalytic power, and improves the overall performance of the catalyst in an auxiliary way by adding another transition metal complex, thereby achieving the performance of hydrogen evolution in water electrolysis similar to that of a platinum-based catalyst, being suitable for hydrogen evolution reaction of electrolytes with different pH values, having better stability and providing an effective way for solving the problem of energy crisis.

(4) The synthesis method is simple and easy to control, has low cost, is green and pollution-free, and the used catalyst has good stability and high catalytic activity and can simply and efficiently catalyze electrolysis water to produce hydrogen.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) image of the CoRu @ NPC-800-0.06 electrocatalyst from example 5 wherein a is at a magnification of 10.00KX and b is at a magnification of 20.00 KX.

FIG. 2 is an X-ray photoelectron spectrum (XPS) of the electrocatalysts of example 4(CoRu @ NPC-700-0.06), example 5(CoRu @ NPC-800-0.06) and example 6(CoRu @ NPC-900-0.06).

FIG. 3 is a graph of the linear cyclic voltammetry (LSV) curves of the Hydrogen Evolution Reaction (HER) of the CoRu @ NPC-800-0.06 electrocatalyst in example 5 in different pH electrolytes.

FIG. 4 shows the electrocatalyst for CoRu @ NPC-800-0.04, CoRu @ NPC-800-0.06, CoRu @ NPC-800-0.08, and Co @ NPC-800 in acidic (0.5mol/L H)₂SO₄Solution) electrolyte, a linear cyclic voltammetric curve (LSV) of a catalytic Hydrogen Evolution Reaction (HER).

Detailed Description

the present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.