CN116121797A

CN116121797A - Self-supporting nickel cobalt boron oxide, preparation method and application thereof

Info

Publication number: CN116121797A
Application number: CN202211569589.8A
Authority: CN
Inventors: 杨化桂; 王睿; 徐皓观; 李晓霞; 刘鹏飞; 毛芳欣; 杨磊; 丁子介
Original assignee: East China University of Science and Technology; CGN Wind Energy Ltd
Current assignee: East China University of Science and Technology; CGN Wind Energy Ltd
Priority date: 2022-12-08
Filing date: 2022-12-08
Publication date: 2023-05-16

Abstract

The invention relates to a self-supporting nickel cobalt boron oxide, a preparation method and application thereof. Adopts an electroless plating method and uses NaBH ₄ As reducing agent, cobalt nitrate hexahydrate and nickel nitrate hexahydrate are used as cobalt source and nickel source, and the electrode substrate is alternatively immersed in the above solution to make its surface grow nickel cobalt boron oxide under the action of chemical reaction. The self-supported catalyst obtained by the method has uniform and firm growth, has the possibility of mass large-area production, and has low preparation cost and reverse reactionThe method has the advantages of short reaction period and high repeatability, and the anode under the alkaline water environment replaces a half-reaction catalyst to promote transformation of the alkaline electrolyzed water hydrogen production industry, so that the hydrogen production cost is reduced, a strategy is provided for developing the high-efficiency electrocatalyst, and high-added-value products and H are continuously produced ₂ Provides a path.

Description

Self-supporting nickel cobalt boron oxide, preparation method and application thereof

Technical Field

The invention relates to a preparation method and application of self-supporting nickel cobalt boron oxide with high-efficiency biomass electrolysis catalytic activity.

Background

Excessive consumption of conventional fossil fuel energy further leads to international energy consumption and environmental degradation problems. The international society has begun to strive to achieve sustainable targets and develop new clean, renewable and zero pollution energy sources. Hydrogen, a renewable energy source, has a high quality energy density (about 120MJ kg ^-1 ) Zero pollution (combustion of produced water) and wide range of uses, show great potential, are a safe, clean and sustainable source of energy, far from carbon recycling in the future, and may be the final form of future energy use.

In the hydrogen production by water electrolysis, two half reactions exist, under different acid-base conditions, the OER reaction involving four electrons exists in the anode process, the problems of slow dynamics, high overpotential and the like exist, and the disadvantages greatly limit the efficiency of the water electrolysis reaction. To circumvent the energy consumption impact of OER on alkaline water hydrogen production, alkaline electrooxidation of organic compounds is considered an alternative to traditional OER processes because it has more favourable thermodynamic considerations and more economic requirements. Biomass is a renewable, high-reserves organic material, 5-Hydroxymethylfurfural (HMF) as one of the biomass, which is evaluated by the U.S. department of energy as one of the most valuable biomass chemicals. The oxidation product 2, 5-furandicarboxylic acid (FDCA) can be used as a biomass replacement precursor of terephthalic acid used in the production of a plurality of commercial polymers, and has high commercial utilization value. Therefore, the HMF electrooxidation is used for replacing OER, so that not only can the hydrogen production energy consumption be reduced, but also high-value added chemicals can be obtained at the anode, and the method has extremely important promotion effect on the alkaline water electrolysis hydrogen production industry in the technical stagnation period.

Based on the above, the invention utilizes a simple method of alternative dipping chemical plating, utilizes cheap non-noble metal to synthesize self-supporting nickel cobalt boron oxide, has uniform and firm growth, has the possibility of mass large-area production, and accords with the preparation and application conditions of commercial electrolytic water electrodes. In the electrolysis of biomass HMF, only an extremely low potential of 1.358V (vs RHE) is required to reach 100mA cm ^-2 The current density of (2) is reduced by nearly 200mV compared with oxygen evolution reaction (1.564V), which is far lower than pure water decomposition. Not only provides a strategy for developing high-efficiency electrocatalyst, but also continuously produces high added value products and H ₂ Provides a path.

Disclosure of Invention

The invention aims to provide a preparation method and application of a self-supporting nickel cobalt boron oxide with high-efficiency biomass electrolysis catalytic activity, and the preparation method is simple and high in repeatability. The prepared material has excellent biomass electrocatalytic activity and selectivity, can effectively reduce the anode energy consumption by being coupled with the electrolysis of alkaline water for hydrogen production, and can produce high-purity and high-value anode value-added chemicals.

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

a preparation method of self-supporting nickel cobalt boron oxide with high-efficiency biomass electrolysis catalytic activity comprises the following steps:

(1) Cobalt nitrate hexahydrate and nickel nitrate hexahydrate are dissolved in deionized water according to the proportion of 50:1 to prepare Co/Ni=0.5:0.01 mol/L aqueous solution which is used as solution A; naBH is carried out ₄ Dissolving in deionized water to prepare 2mol/L NaBH ₄ An aqueous solution was used as solution B and was usedNaOH adjusts the pH of the solution to 13 to prevent self-decomposition of NaBH 4.

(2) Catalyst support substrates (e.g., nickel foam, carbon paper, etc.) are supported at 50cm ² 200mL of solution A is soaked in the solution A to enable the solution A to be fully adsorbed on the surface of the substrate; then the deionized water is evaporated in a heating table at 200 ℃ to crystallize the nickel and cobalt precursors on the surface of the substrate, and the process is repeated three times.

(3) And (3) rapidly immersing the substrate fully adsorbing the nickel-cobalt precursor in the solution B, standing for 10 seconds, taking out, then immersing in the solution A again, fully reacting for 10 seconds, and taking out. And taking the solution as a circulation, and stopping after the solution B bubbles are not generated any more after the solution B bubbles are alternately immersed for multiple circulation, thus obtaining the self-supporting nickel cobalt boride electrocatalyst.

(4) And repeatedly washing the self-supporting nickel cobalt boron oxide electrocatalyst by using deionized water and ethanol, washing the catalyst and the solution which do not successfully grow, and naturally air-drying and oxidizing in an air environment to obtain the self-supporting nickel cobalt boron oxide electrocatalyst.

Furthermore, the invention provides a self-supporting nickel cobalt boron oxide electrocatalyst for coupling biomass electrolysis catalysis with alkaline electrolysis water to produce hydrogen.

The application method comprises the following steps:

(1) Under the environment of conventional water electrolysis hydrogen production, namely 1mol per liter of potassium hydroxide (1.0M KOH) water solution, 10mmol of HMF is added as electrolyte solution, the self-supporting nickel cobalt boron oxide (electrode area is 1 multiplied by 1 cm) described in the requirement 1 ² ) As working electrode, silver-silver chloride electrode is used as reference electrode, platinum net electrode is used as counter electrode, test temperature is 15-25 deg.C, and test is conducted in H-type electrolytic cell. An extremely low potential of 1.358V (vs RHE) is required to reach 100mA cm ^-2 The current density of (2) is reduced by nearly 200mV compared with oxygen evolution reaction (1.564V), which is far lower than pure water decomposition. And under 7-cycle test, the conversion rate of HMF is 100%, and the yield of FDCA is over 94%.

(2) In an anion exchange membrane alkaline water electrolytic tank, full cell testing is carried out to simulate an industrial electrolytic water environment. 1mol per liter of aqueous potassium hydroxide (1.0M KOH) 10mmol of HMF was added as electrolyte solution as described in claim 1And taking the self-supporting nickel cobalt boron oxide as an anode electrode, and taking the NiMo alloy grown on the foam nickel as a cathode electrode to perform full-cell performance test. Compared with sodium carbonate water electrolysis (2.18V), the battery voltage of only about 1.7V can reach 500mA cm ^-2 And has good catalyst stability under the condition of industrial concentrated alkali (6M KOH).

The invention has the beneficial effects that:

(1) The low-cost nickel salt, cobalt salt and sodium borohydride are adopted as main raw materials, all reagents are commercial products, no further treatment is needed, and the preparation cost of the electrode is reduced.

(2) The synthesis process is simple, the preparation period is short, the size proportion of the electrode can be customized and adjusted individually by adjusting the dosage of the synthesis liquid, and the method meets the large-scale production conditions of commercial electrolytic hydrogen production electrodes;

(3) The prepared self-supporting nickel cobalt boride electrocatalyst performs biomass electrooxidation reaction in alkaline electrolyte, and can reach 100mA cm only by extremely low potential of 1.358V (vs RHE) ^-2 The current density of (2) is reduced by nearly 200mV compared with oxygen evolution reaction (1.564V), which is far lower than pure water decomposition. Under 7 cycle tests, the conversion rate of HMF is 100%, and the yield of FDCA is over 94%; in the anion exchange membrane alkaline water electrolysis cell, compared with sodium carbonate water electrolysis (2.18V), the full-cell test can reach 500mA cm by only about 1.7V of cell voltage ^-2 And has good catalyst stability under the condition of industrial concentrated alkali (6M KOH); the prepared self-supporting nickel cobalt boride electrocatalyst has good catalytic activity, is suitable for use environment of commercial electrolyzed water with high current density, and can be effectively used in industrial operation environment.

Drawings

FIG. 1 is a scanning electron microscope of the product prepared in example 1 before and after the reaction;

FIG. 2 is an X-ray photoelectron spectrum of cobalt before and after the reaction of the product prepared in example 1;

FIG. 3 is an X-ray photoelectron spectrum of nickel element before and after the reaction of the product prepared in example 1;

FIG. 4 is an R-space diagram of cobalt element of the product prepared in example 1 before and after the reaction and standard cobalt foil.

Fig. 5 is a linear scan curve of the product prepared in example 1 directly as a working electrode in alkaline electrolyte and HMF solution.

Fig. 6 is a catalytic selectivity test of the product prepared in example 1 directly as a working electrode in alkaline electrolyte and HMF solution.

FIG. 7 is a full cell tested anion exchange membrane alkaline water electrolyzer device of the product prepared in example 1

FIG. 8 is a linear scan of the product prepared in example 1 for a full cell test in an anion exchange membrane alkaline water electrolysis cell.

Detailed Description

The following describes the embodiments of the present invention in further detail with reference to the drawings and examples, but should not be construed as limiting the scope of the invention.

"Range" is disclosed herein in the form of lower and upper limits. There may be one or more lower limits and one or more upper limits, respectively. The given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular ranges. All ranges that can be defined in this way are inclusive and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, ranges of 60-120 and 80-110 are listed for specific parameters, with the understanding that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the

minimum range values

1 and 2 are listed, and if the

maximum ranges

3,4 and 5 are listed, the following ranges are all contemplated: 1-2, 1-4, 1-5, 2-3, 2-4 and 2-5.

In the present invention, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values.

In the present invention, all the embodiments mentioned herein and the preferred embodiments may be combined with each other to form new technical solutions, if not specifically described.

In the present invention, all technical features mentioned herein and preferred features may be combined with each other to form new technical solutions, if not specifically stated.

Preferred embodiments of the present invention will be specifically described below with reference to specific embodiments, but it should be understood that reasonable variations, modifications and combinations of these embodiments can be made by those skilled in the art without departing from the scope of the present invention as defined in the appended claims, thereby obtaining new embodiments, and these new embodiments obtained by variations, modifications and combinations are also included in the scope of protection of the present invention.

Example 1

Step one, preparation of self-supporting nickel cobalt boron oxide electrocatalyst

7. Cobalt nitrate hexahydrate and nickel nitrate hexahydrate are dissolved in deionized water according to the proportion of 50:1 to prepare Co/Ni=0.5:0.01 mol/L aqueous solution which is used as solution A; naBH is carried out ₄ Dissolving in deionized water to prepare 2mol/L NaBH ₄ An aqueous solution was used as solution B, and the pH of the solution was adjusted to 13 with NaOH to prevent NaBH ₄ Self-decomposition occurs. Catalyst support substrates (e.g., nickel foam, carbon paper, etc.) are supported at 50cm ² 200mL of solution A is firstly immersed in the solution A to enable the solution A to be fully adsorbed on the surface of the substrate, deionized and evaporated on a heating table at 200 ℃ to enable nickel and cobalt precursors to be crystallized on the surface of the substrate, and the process is repeated three times; and then the substrate which fully adsorbs the nickel cobalt precursor is quickly immersed in the solution B for standing for 10 seconds and then taken out, and then immersed in the solution A again for fully reacting for 10 seconds and then taken out. Taking the solution as a circulation, and stopping after the solution B bubbles are not generated any more after the solution B bubbles are alternately immersed for a plurality of circulation. And finally, repeatedly washing the electrode by using deionized water and ethanol, cleaning the catalyst and the solution which do not grow successfully, and naturally air-drying and oxidizing in an air environment to obtain the required self-supporting nickel cobalt boron oxide.

FIG. 1 is a scanning electron microscope picture of the prepared self-supporting nickel cobalt boron oxide before and after reaction. It can be seen that the shape of the catalyst is changed before and after the reaction, the material before the reaction is in an irregular nano sphere shape, and the material after the reaction is in a polygonal nano plate shape.

FIG. 2 is an X-ray photoelectron spectrum of cobalt before and after the reaction of the prepared self-supporting nickel cobalt boron oxide. Wherein the diffraction peak at 782.6/797.8eV and the diffraction peak at 780.8/796.3eV shown in the X-ray photoelectron spectrum before reaction are CoO or Co (OH) ₂ Co of (C) ²⁺ The other diffraction peaks are satellite peaks, and 779.6/794.6eV Co appears after the reaction ³⁺ Indicating that the materials are reconstructed before and after the reaction to generate Co with excellent catalytic activity ³⁺ The components are as follows.

FIG. 3 is an X-ray photoelectron spectrum of nickel element before and after the reaction of the prepared self-supporting nickel cobalt boron oxide. Wherein the diffraction peak at 855.8/873.1eV corresponds to Ni ²⁺ The two diffraction peaks at 861.9 and 883.4eV are satellite peaks. From the X-ray photoelectron spectrum, the valence state of the nickel element is not changed before and after the reaction, so that it can be concluded that Ni is not a reactive site of the electrocatalytic biomass. However, the binding energy shifts to the low energy direction after the reaction, which indicates that Ni is doped to regulate the electron transfer of the cobalt active site, and accelerates the Co of the active site ³⁺ The components are produced.

Fig. 4 is an R-space diagram of cobalt element of the prepared self-supporting nickel cobalt boron oxide before and after reaction and standard cobalt foil. The method is obtained by carrying out Fourier transformation on the expansion edge of the X-ray absorption fine structure spectrum, and can qualitatively analyze microcosmic coordination information of products. Wherein: curve 1 is the curve before the reaction of the self-supporting nickel cobalt boron oxide prepared in example 1; curve 2 is the curve after the reaction of the self-supporting nickel cobalt boron oxide prepared in example 1; curve 3 is the curve of a standard cobalt foil.

As can be seen from FIG. 4, in

Cobalt-cobalt coordination for standard cobalt foil; 1.46 and->

The peaks at these sites are respectively assigned to cobalt oxide and cobalt coordination of the cobalt oxyhydroxide. The main peak before the reaction is close to +.>

But slightly reduced, possibly due to nickel-cobalt coordination or the influence of cobalt-nickel coordination caused by the existence of nickel element and boron element; after the reaction, cobalt oxide corresponding to the cobalt oxyhydroxide and cobalt coordination appear, which indicates that the material has a reconstruction phenomenon during the reaction, and a real trivalent cobalt active site is generated.

Step two, performance characterization test

And directly taking the prepared self-supporting nickel cobalt boron oxide as a working electrode to perform electrochemical characterization test. The prepared self-supporting nickel cobalt boron oxide electrode was placed in 1.0M KOH and 10mmol HMF in water using a CHI760 electrochemical workstation, a standard three electrode system, and a linear scan test and cycle performance test were performed using conventional methods.

Fig. 5 is a linear scan curve of the prepared self-supporting nickel cobalt boron oxide as a working electrode directly in alkaline electrolyte and HMF solution in step two. Wherein: curve 1 is a linear scan curve under test conditions of a prepared self-supporting nickel cobalt boron oxide as a working electrode, a silver-silver chloride electrode as a reference electrode, a platinum mesh as a counter electrode, 1.0MKOH+10mmol HMF aqueous solution as electrolyte, and a scan speed of 5mV/s at a test temperature of 15-25 ℃. Curve 2 is a linear scan curve under test conditions of 1.0M KOH+10mmol HMF aqueous solution as electrolyte, test temperature of 15-25℃and scan speed of 5 mV/s.

As can be seen from FIG. 5, the prepared self-supporting nickel cobalt boron oxide can reach 10mA cm under the condition that HMF is an electrolyte only by 1.257V (vs RHE) ^-2 Is a current density of (a); can reach 100mA cm at very low potential of 1.358V (vs RHE) ^-2 The current density of (2) is reduced by nearly 200mV compared with oxygen evolution reaction (1.564V), which is far lower than pure water decomposition.

Fig. 6 is a catalytic selectivity test of the prepared self-supporting nickel cobalt boron oxide as a working electrode directly in alkaline electrolyte and HMF solution in step two. There were extremely high HMF conversion and FDCA yields in the seven HMF electrooxidation cycles tested. The HMF conversion rate is 100%, and the yield of 2, 5-furandicarboxylic acid (FDCA) is more than 94%.

Step three, membrane electrode test simulation

In an anion exchange membrane alkaline water electrolytic tank, full cell testing is carried out to simulate an industrial electrolytic water environment. And taking the prepared self-supporting nickel cobalt boron oxide as an anode electrode, and taking NiMo alloy growing on foam nickel as a cathode electrode to perform full-cell performance test.

Fig. 7 is a full cell test device for an anion exchange membrane alkaline water electrolysis cell.

Fig. 8 is a linear scan curve of a full cell test performed in an anion exchange membrane alkaline water electrolysis cell. Curve 1 is a test curve of an anode coupling electrolytic hydrogen production device with 10mmol HMF added into 1mol/L potassium hydroxide (1.0M KOH) aqueous solution as electrolyte solution; curve 2 is a test curve for a conventional electrolytic hydrogen production device with 1 mole per liter of aqueous potassium hydroxide (1.0 m koh) solution as the electrolyte solution.

As can be seen from FIG. 7, in the anion exchange membrane alkaline water electrolysis cell, the battery voltage of about 1.7V was higher than that of the sodium carbonate water electrolysis cell (2.18V) by 500mA cm when the full battery test was performed ^-2 。

According to the invention, the micro-electronic structure of the catalyst is changed by doping a small amount of Ni, more active sites are easier to form in the electrocatalytic process of the alkaline solution of 5-hydroxymethylfurfural, the reaction performance is improved, and excellent catalytic activity is shown. The slow kinetics inherent to the oxygen evolution reaction limit the improvement in hydrogen evolution reaction performance, while the anodic oxidation of alternative biomass materials is an alternative method because of its lower oxidation potential and higher additional product values compared to biomass materials. The prepared self-supporting nickel cobalt boron oxide is used as an anode to replace a semi-reaction material, and has higher electrocatalytic performance and product selectivity. In the future, the HMF is introduced as a new anode electrode for hydrogen production by using commercial alkaline water, so that transformation of the alkaline water electrolysis hydrogen production industry can be promoted, the hydrogen production cost is reduced, a strategy is provided for developing a high-efficiency electrocatalyst, and high-added-value products and H are continuously produced ₂ Provides a path.

Claims

1. The preparation method of the self-supporting nickel cobalt boron oxide is characterized by comprising the following steps of:

preparing a cobalt precursor and a nickel precursor into a solution A; and (3) taking the sodium borohydride aqueous solution as an electroless plating reducer to be named as a solution B, alternatively immersing the electrode support substrate in the A, B solution until the reaction is finished, and washing and drying to obtain the self-supporting nickel cobalt boron oxide electrocatalyst.

2. The preparation method of claim 1, wherein the solution a is prepared by dissolving cobalt nitrate hexahydrate and nickel nitrate hexahydrate in deionized water at a ratio of 50:1 to prepare an aqueous solution of Co/ni=0.5:0.01 mol/L.

3. The method according to claim 1, wherein the solution B is prepared by mixing NaBH ₄ Dissolving in deionized water to prepare 2mol/L NaBH ₄ An aqueous solution was used as solution B, and the pH of the solution was adjusted to 13 with NaOH to prevent NaBH ₄ Self-decomposition occurs.

4. The method of claim 1, wherein the electrode support substrate is a catalyst support substrate in a ratio of 50cm compared to solution A ² 200mL of solution A.

5. The preparation method according to claim 1, wherein the steps of immersing the materials in A, B solution alternately until the reaction is finished are as follows: firstly, immersing in the solution A to enable the solution A to be fully adsorbed on the surface of the substrate; then deionized and evaporated in a heating table at 200 ℃ to crystallize the nickel and cobalt precursors on the surface of the substrate, and repeating the process for three times; rapidly immersing a substrate fully adsorbing the nickel-cobalt precursor into the solution B, standing for 10 seconds, taking out, then immersing the substrate again into the solution A, fully reacting for 10 seconds, and taking out; taking the solution as a circulation, and stopping after the solution B bubbles are not generated any more after the solution B bubbles are immersed for a plurality of circulation alternately.

6. The preparation method of the self-supported nickel cobalt boron oxide electrocatalyst according to claim 1, wherein the method for obtaining the self-supported nickel cobalt boron oxide electrocatalyst after washing cleanly and drying is that the self-supported nickel cobalt boron oxide electrocatalyst is repeatedly washed by deionized water and ethanol, and the catalyst and the solution which are not grown are naturally air-dried and oxidized in an air environment to obtain the required self-supported nickel cobalt boron oxide.

7. A self-supporting nickel cobalt boron oxide produced by the method of claim 1.

8. Use of the self-supporting nickel cobalt boron oxide according to claim 7, wherein the self-supporting nickel cobalt boron oxide electrocatalyst is used for biomass electrolysis catalysis coupled with alkaline electrolysis of water to produce hydrogen.

9. The use according to claim 8, characterized in that the application method is as follows:

(1) Adding 5-hydroxymethylfurfural into a potassium hydroxide aqueous solution under the environment of conventional water electrolysis hydrogen production to serve as an electrolyte solution, wherein the self-supporting nickel cobalt boron oxide serves as a working electrode, a silver-silver chloride electrode serves as a reference electrode, a platinum mesh electrode serves as a counter electrode, the test temperature is 15-25 ℃, and the test is carried out in an H-type electrolytic cell;

(2) In an anion exchange membrane alkaline water electrolytic tank, performing full-cell test to simulate an industrial electrolytic water environment;

and adding 5-hydroxymethylfurfural into a potassium hydroxide aqueous solution to serve as an electrolyte solution, wherein the self-supporting nickel cobalt boron oxide serves as an anode electrode, and NiMo alloy growing on foam nickel serves as a cathode electrode to perform full-cell performance test.