阅读说明：本技术 一种Ru修饰FeCo@NF电催化剂的制备方法及应用 (Preparation method and application of Ru-modified FeCo @ NF electrocatalyst ) 是由 刘苏莉 戴世鹏 陈嘉冰 顾祥耀 尚鸣 费蓉碧 朱金晶 陈雨 穆雪琴 于 2021-09-18 设计创作，主要内容包括：本发明提供一种Ru修饰FeCo@NF电催化剂的制备方法,所述Ru修饰FeCo@NF电催化剂包括FeCoRu@NF纳米花和FeCoRu@NF纳米球；其中,所述FeCoRu@NF纳米花的制备方法包括下述步骤：将FeCo@NF纳米片、RuCl-(3)、甲醇混合,常温反应,得到FeCoRu@NF纳米花；所述FeCoRu@NF纳米球的制备方法包括下述步骤：将FeCo@NF纳米片、RuCl-(3)、乙二醇、水混合,升温,保温反应,得到FeCoRu@NF纳米球。本发明还提供一种所述Ru修饰FeCo@NF电催化剂组装成电解水制氢体系的阴极和阳极。本发明具备新型、高效、廉价及双功能性的特点。(The invention provides a preparation method of a Ru-modified FeCo @ NF electrocatalyst, wherein the Ru-modified FeCo @ NF electrocatalyst comprises FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres; the preparation method of the FeCoRu @ NF nanoflower comprises the following steps of: FeCo @ NF nanosheet and RuCl 3 Mixing the solution and methanol, and reacting at normal temperature to obtain FeCoRu @ NF nanoflower; the preparation method of the FeCoRu @ NF nanosphere comprises the following steps of: FeCo @ NF nanosheet and RuCl 3 Mixing the FeCoRu nanosphere with glycol and water, heating, and carrying out heat preservation reaction to obtain the FeCoRu @ NF nanosphere. The invention also provides a cathode and an anode of the water electrolysis hydrogen production system assembled by the Ru modified FeCo @ NF electrocatalyst. The invention has the characteristics of novelty, high efficiency, low price and dual functions.)

1. A preparation method of a Ru-modified FeCo @ NF electrocatalyst is characterized in that the Ru-modified FeCo @ NF electrocatalyst comprises FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres;

the preparation method of the FeCoRu @ NF nanoflower comprises the following steps of: FeCo @ NF nanosheet and RuCl₃Mixing the solution and methanol, and reacting at normal temperature to obtain FeCoRu @ NF nanoflower;

the preparation method of the FeCoRu @ NF nanosphere comprises the following steps of: FeCo @ NF nanosheet and RuCl₃Mixing the FeCoRu nanosphere with glycol and water, heating, and carrying out heat preservation reaction to obtain the FeCoRu @ NF nanosphere.

2. The method for preparing the Ru-modified FeCo @ NF electrocatalyst according to claim 1, wherein the reaction time at normal temperature is 15 min.

3. The method for preparing a Ru-modified FeCo @ NF electrocatalyst according to claim 1, wherein the rate of temperature increase is 1.7 ℃/min.

4. The method for preparing the Ru-modified FeCo @ NF electrocatalyst according to claim 1, wherein the temperature of the incubation reaction is 130 ℃ and the time is 2.5 h.

5. The method of preparing the Ru-modified FeCo @ NF electrocatalyst of claim 1, wherein the RuCl is₃The mass to volume ratio (mg/ml) with methanol was 4: 1.

6. The method of preparing the Ru-modified FeCo @ NF electrocatalyst of claim 1, wherein the RuCl is₃The mass to volume ratio (mg/ml) with ethylene glycol was 20: 3.

7. The method for preparing a Ru-modified FeCo @ NF electrocatalyst according to claim 1, wherein the volume ratio of ethylene glycol to water is 1: 1.

8. The method for preparing a Ru-modified FeCo @ NF electrocatalyst according to claim 1, wherein the product of the incubation reaction is washed with an ethanol solution.

9. The application of the Ru modified FeCo @ NF electrocatalyst prepared by the preparation method of any one of claims 1-8 in assembling a water electrolysis hydrogen production system, wherein the water electrolysis hydrogen production system contains an OER catalyst and an HER catalyst; the OER catalyst is FeCoRu @ NF nanospheres, and the HER catalyst is FeCoRu @ NF nanospheres.

Technical Field

The invention relates to the technical field of electrocatalysts, in particular to a preparation method and application of a Ru-modified FeCo @ NF electrocatalyst.

Background

The electrolysis of water into hydrogen and oxygen using intermittent energy such as solar and wind energy is currently considered an attractive method to produce clean hydrogen energy for fuel cells and other equipment. The method is helpful to solve the problems of energy crisis and environmental pollution caused by over consumption of fossil fuels. The electrolytic water has a large reaction energy barrier and a high overpotential, and a highly active Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) electrocatalyst is required to accelerate the reaction.

At present, the high-efficiency HER and OER electrocatalysts are mainly based on noble metals Pt and Ru/Ir oxide respectively, and although they show lower initial overpotentials, they are at high current density (the current density of industrial electrolyzed water can be as high as 500-1000 mA/cm)²) The overpotential of (a) is still high, while scarcity and high cost limit their large-scale application. Scientists have therefore been working on developing abundant OER catalysts to electrolyze water in alkaline systems, such as transition metal oxides, hydroxides, sulfides, phosphides, nitrides and carbon nanomaterials. It is well known that FeCo oxides and hydroxides have a high OER catalytic activity in alkaline media. Recent studies have shown that self-supporting and binderless nanoarrays are an effective electrode structure that can improve charge transfer and mass transfer in OERs (Energy environ. sci.,2017,10, 1820). However, to meet the standards for industrial applications, OER electrocatalysts are required to be operated at high current densities (≧ 500 mA/cm)²) And stable operation at low overpotentials (< 300 mV) for a relatively long time, which remains a significant challenge for current non-noble metal OER electrocatalysts.

Generally, to ensure stable operation of an electrocatalyst at high current densities, the active sites should satisfy the conditions of (i) high intrinsic activity, (ii) high surface area, (iii) ease of contact by the reactants while conducting electrons to the external circuit, and (iv) corrosion resistance under strong oxidizing conditions. In addition, the electrocatalyst must adhere strongly to the substrate to prevent its exfoliation during long-term electrocatalysis. However, conventional electrocatalysts modified onto electrodes tend to have poor electrochemical and mechanical stability under high current density and strong gas evolution conditions. Therefore, it is necessary to design a bifunctional electrocatalyst with high catalytic activity, high structural stability and high electrical conductivity to achieve industrial application of high current density.

In Pt group metals, Ru is easy to adsorb reaction substrates on the surface because d electron orbits are not filled up, and an active intermediate product is generated and has high catalytic activity. It has excellent catalytic performance in dehydrogenation, hydrogenation, oxidation, reduction, cracking, synthesis, isomerization and the like. For example, Weizidong et al, Chongqing university, proposed a "lattice-confined-domain" Ru @ TiO "with metal cluster embedded oxides₂A catalyst. This metal-bonded lattice-restricted domain structure leads to interfacial Ru which, on the one hand, has a structure which is bonded to TiO₂The oxides have a similar atomic arrangement structure while retaining their intrinsic metallic properties, exhibiting mesoscale behavior distinct both from the Ru bulk metal and from the Ru nanoclusters. In acidic and basic media, Ru @ TiO₂The HOR mass activity of the catalyst is 30% higher than that of a commercial Pt/C catalyst. Ruthenium (Ru) nanoclusters which are doped with oxygen and have the diameter of only 2nm are designed by people such as Yuji America of Chinese university of hong Kong, China, to form a unique Ru @ oxygen-doped Ru core-shell structure. In addition, the Ru resource is relatively rich, the price of the Ru is only about 4% of that of the Pt, and the Ru-Pt composite material has a wide application prospect. However, Ru, like other metals in the Pt group, has problems such as poor catalytic stability at high current density, and limits its industrial application to some extent, so how to further improve catalytic activity and electrochemical stability of Ru-based catalysts at high current density faces a great challenge.

Disclosure of Invention

Aiming at the prior art, the invention provides a preparation method and application of a Ru-modified FeCo @ NF electrocatalyst, which can be applied to the total hydrolysis reaction of an alkaline fuel cell under high current density, can efficiently catalyze hydrogen evolution and oxygen evolution reactions, and has the characteristics of novelty, high efficiency, low price and dual functionality.

The invention provides a preparation method of a Ru-modified FeCo @ NF electrocatalyst, wherein the Ru-modified FeCo @ NF electrocatalyst comprises FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres;

the preparation method of the FeCoRu @ NF nanoflower comprises the following steps of: FeCo @ NF nanosheet and RuCl₃Mixing the solution and methanol, and reacting at normal temperature to obtain FeCoRu @ NF nanoflower;

the preparation method of the FeCoRu @ NF nanosphere comprises the following steps of: FeCo @ NF nanosheet and RuCl₃Mixing the FeCoRu nanosphere with glycol and water, heating, and carrying out heat preservation reaction to obtain the FeCoRu @ NF nanosphere.

The preparation method of the FeCo @ NF nanosheet comprises the following steps: and sequentially and respectively adding absolute ethyl alcohol, hydrochloric acid and deionized water into the blank foamed nickel, performing ultrasonic treatment for 15min respectively, and drying. Adding 2, 5-dihydroxyterephthalic acid, anhydrous iron acetate, cobalt nitrate hexahydrate and N, N-dimethylformamide into the processed blank foamed nickel to obtain a mixed solution, heating to 120 ℃, preserving heat for 24 hours, washing the product with ethanol, and repeating for 2-3 times to obtain the FeCo @ NF nanosheet electrocatalyst.

Preferably, the addition ratio of each material component at the beginning of each part of FeCo @ NF nanosheet electrocatalyst is as follows: blank foam nickel: 2cm х 3 cm; 2, 5-dihydroxyterephthalic acid: 0.45 mmol; anhydrous iron acetate: 0.27 mmol; cobalt nitrate hexahydrate: 0.72 mmol; n, N-dimethylformamide: 30 mL.

Preferably, the time of the normal-temperature reaction is 15 min.

Preferably, the rate of temperature rise is 1.7 ℃/min.

Preferably, the temperature of the heat preservation reaction is 130 ℃ and the time is 2.5 h.

Preferably, the RuCl₃Mass to volume ratio with methanol(mg/ml) was 4: 1.

Preferably, the RuCl₃The mass to volume ratio (mg/ml) with ethylene glycol was 20: 3.

Preferably, the volume ratio of ethylene glycol to water is 1: 1.

Preferably, the product of the incubation reaction is washed with an ethanol solution.

The invention also provides an application of the Ru modified FeCo @ NF electrocatalyst prepared by the preparation method in assembling a water electrolysis hydrogen production system, wherein the water electrolysis hydrogen production system contains an OER catalyst and an HER catalyst; the OER catalyst is FeCoRu @ NF nanospheres, and the HER catalyst is FeCoRu @ NF nanospheres.

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

1. the invention utilizes an in-situ growth method to modify Ru with different loads on FeCo @ NF nano-sheets to respectively obtain FeCoRu @ NF nano-flowers and FeCoRu @ NF nano-spheres, main elements of the alloy nano-crystals are Fe, Co and Ru, the FeCoRu @ NF nano-flowers have excellent Oxygen Evolution Reaction (OER) performance, and the FeCoRu @ NF nano-spheres have excellent Hydrogen Evolution Reaction (HER) performance which is respectively superior to that of RuO @ NF nano-spheres sold in the market at present₂Commercial catalysts and commercial Pt/C catalysts. FeCoRu @ NF nanoflower and FeCoRu @ NF nanosphere are assembled into cathode and anode of water electrolysis hydrogen production system, have excellent total hydrolysis (OWS) performance and are superior to FeCo-based catalysts in literature and commercial Pt/C | | | RuO₂A catalyst.

2. The invention adopts a solvent thermal method, has the advantages of simple process, low reaction temperature, short time and the like, and is suitable for batch production. The catalytic performance of the FeCo @ NF electrocatalyst is effectively adjusted by doping different Ru loads, and the FeCo @ NF electrocatalyst can reach the standard of industrial application, for example, in OER, the FeCoRu @ NF nanoflower electrocatalyst can be used in high current density (more than or equal to 500 mA/cm)²) The stable operation is carried out for a long time, which has important guiding significance for the technical development of renewable energy sources.

Drawings

FIG. 1 is SEM and mapping images of FeCo @ NF nanosheets in the examples of the present invention.

FIG. 2 is SEM and mapping images of FeCoRu @ NF nanoflower in an embodiment of the invention.

FIG. 3 is an OER performance test chart of FeCoRu @ NF nanoflower in the embodiment of the invention.

FIG. 4 is SEM and mapping images of FeCoRu @ NF nanospheres in an embodiment of the invention.

FIG. 5 is a HER performance test chart of FeCoRu @ NF nanospheres in the example of the invention.

FIG. 6 is an XPS comparison of FeCo @ NF nanosheets, FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres in the examples of the present invention.

FIG. 7 is a graph showing the OWS performance test of FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres in the experimental examples of the present invention.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the specific drawings.

Examples

A preparation method of a Ru modified FeCo @ NF electrocatalyst comprises the following steps:

step 1: weighing 90mg (0.45mmol) of 2, 5-dihydroxyterephthalic acid, 47mg (2.3 mmol) of anhydrous iron acetate and 210mg (0.72 mmol) of cobalt nitrate hexahydrate at room temperature, adding the raw materials into a dry reaction kettle with the capacity of 50mL, measuring 30mL of N by using a liquid transfer gun, adding N-dimethylformamide into the reaction kettle, uniformly mixing to obtain a mixed solution, and adding blank foamed nickel. And (3) transferring the reaction kettle into an oven, raising the temperature to 120 ℃ at the speed of 1.7 ℃/min under the programmed temperature control, preserving the temperature for 24 hours, after the reaction is finished, naturally cooling the reaction kettle to the room temperature, washing the reaction kettle by using ethanol to obtain a product FeCo @ NF nano sheet, and drying the product in vacuum at the temperature of 60 ℃ for analysis and characterization.

As shown in figure 1, by adopting the characterization means such as SEM and Mapping test, the prepared FeCo @ NF electrocatalyst has a nanosheet structure, and the elements Fe, Co, Ni and O can be obtained through element Mapping test, wherein the elements Ni and O come from a substrate NF.

Step 2: weighing 100mg of RuCl at room temperature₃Adding into a dry beaker with the volume of 50mL, and transferring by liquid25mL of methanol was measured by a gun and added to a beaker, and the mixture was mixed by sonication to obtain a solution. Transferring the solution into a 50mL pointed-bottom centrifuge tube, adding FeCo @ NF nanosheets at normal temperature, soaking for 15min to obtain FeCoRu @ NF nanoflowers serving as products, and drying in vacuum at 60 ℃ for analysis and characterization.

As shown in FIG. 2, by adopting the characterization means such as SEM and Mapping test, the prepared FeCoRu @ NF electrocatalyst has a nanoflower structure, and the elements Ru, Fe, Co, Ni and O can be obtained through the element Mapping test, wherein the elements Ni and O come from the substrate NF.

As shown in the OER performance test of FIG. 3, the current density was 1000mA/cm²Its overpotential is 246mV much smaller than commercial RuO₂280mV of catalyst and 1000mA/cm²The catalyst can be kept stable for 200 hours, and the performance is far superior to that of the most advanced industrial catalyst at present.

And step 3: weighing 100mg of RuCl at room temperature₃Adding into a dry beaker with a capacity of 50mL, and measuring 15mL EG and 15mL H by using a pipette₂0, adding the mixture into a beaker, and uniformly mixing the mixture by ultrasonic waves to obtain a solution. Transferring the solution into a dry reaction kettle with the capacity of 50mL, adding FeCo @ NF nanosheet, and heating to 120 ℃ at the speed of 1.7 ℃/min^oC, preserving the temperature for 30 min, finishing the reaction, naturally cooling the reactor to room temperature, washing the reactor by ethanol to obtain FeCoRu @ NF nanospheres which are 60^oAnd C, drying in vacuum for analysis and characterization.

As shown in FIG. 4, by adopting the characterization means such as SEM and Mapping test, the prepared FeCoRu @ NF electrocatalyst has a nano-spherical structure, and the elements Ru, Fe, Co, Ni and O can be obtained by the element Mapping test, wherein the elements Ni and O come from the substrate NF.

As shown in the HER performance test of FIG. 5, the current density was 1000mA/cm²The overpotential is 117 mV, the Tafel slope is 63 mV/dec, which is much less than 363 mV of FeCo @ NF nanosheets (the Tafel slope is 147 mV/dec). And 1000mA/cm²The catalyst can be kept stable for 40 hours, and the performance is far superior to that of the most advanced industrial catalyst at present.

Furthermore, XPS photoelectrons as in FIG. 6The energy spectrum characterization structure shows that the Fe 2p orbital consists of Fe 2p3/2 at the binding energy of 711.06 eV and Fe 2p1/2 at the binding energy of 723.50 eV, and the result shows that the Fe element is mainly Fe³⁺The Co 2p orbital is mainly composed of two pairs of main peaks of Co 2p2/3 and Co 2p1/2, the first pair of main peaks are respectively positioned at the binding energy of 796.11 eV and 780.43 eV, which shows that the Co 2p orbital is formed by the two pairs of main peaks³⁺The presence of the second pair of main peaks at the binding energies 797.58 eV and 782.04 eV, respectively, indicates that Co is present²⁺The Ni 2p orbital is mainly composed of two pairs of main peaks of Ni 2p2/3 and Ni 2p1/2, the first pair of main peaks are respectively positioned at binding energy 855.15 eV and 872.70 eV, which shows that Ni is in a negative shift compared with FeCo @ NF²⁺The presence of the second pair of main peaks at the binding energies 856.15 eV and 874.36 eV, respectively, indicates Ni³⁺Compared with FeCo @ NF nanosheets, negative offset also exists; the Ru 3p orbital consists essentially of two pairs of major peaks, which indicate primarily the presence of elemental ruthenium at valence 0 and the presence of oxidized Ru^x+. SEM and XPS combined analysis results show that FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres are Ru-modified FexCo_1-xAn oxyhydroxide compound.

Test examples

FeCoRu @ NF nanoflowers and FeCoRu @ NF nanospheres prepared in the embodiment are used as OER and HER catalysts to be assembled into a cathode and an anode of an electrolyzed water hydrogen production system (FeCoRu @ NF nanoflowers | | FeCoRu @ NF nanospheres) to test the catalytic performance of the electrolyzed water. As shown in FIG. 6, the test result shows that the FeCoRu @ NF nanoflower | | | FeCoRu @ NF nanosphere electrolyzed water hydrogen production system can reach 1000mA/cm only by 1.52V of voltage²The current density of (1) is far lower than that of commercial Pt/C RuO₂(1.85V，500mA/cm²) An electrolytic cell. Meanwhile, the FeCoRu @ NF nanoflower | | | FeCoRu @ NF nanosphere water electrolysis hydrogen production system exceeds 1000mA/cm²The high-current density has higher stability (at least 200 hours) and is better than Pt/C RuO₂The system for producing hydrogen by electrolyzing water shows potential application value.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures made by using the contents of the present specification and the drawings can be directly or indirectly applied to other related technical fields, and are within the scope of the present invention.