Cr and N co-doped NiMo array electrode and preparation method and application thereof

Abstract

The invention discloses a Cr and N co-doped NiMo array electrode and a preparation method and application thereof, and belongs to the field of nanometer material synthesis and energy environment science and engineering application. Renewable energy fluctuation can cause unstable working conditions of voltage and current of an alkaline water electrolysis system and destroy geometric and electronic structures of a catalyst. Compared with a non-doped NiMo electrode, the prepared Cr and N co-doped NiMo array electrode has the advantages that the electron transmission efficiency and alkaline water hydrogen production performance of the initial NiMo electrode can be effectively improved by doping Cr and N, and the hydrogen evolution activity and stability improvement effect under the condition of fluctuating current are very remarkable.

Description

Technical Field

[0001] The invention belongs to the field of nano material synthesis and energy science and engineering application, and specifically relates to a Cr and N co-doped NiMo array electrode and a preparation method and application thereof. Background Art

[0002] With the continuous growth of global energy demand and the increasing awareness of environmental protection, the development of clean, efficient and sustainable energy systems has become an important direction of current scientific and technological development. As a clean energy carrier, hydrogen has shown great application potential in the field of energy storage and conversion. As an effective method of converting electrical energy into hydrogen energy, the key technology of water electrolysis lies in the research and development of efficient and stable electrocatalysts.

[0003] NiMo alloy catalysts exhibit good catalytic activity in the process of hydrogen production from alkaline water due to their unique electronic structure and excellent conductivity. Studies have shown that the electronic synergy between the two NiMo atoms has a very suitable adsorption energy for proton H, thereby reducing the overpotential of hydrogen production from water electrolysis and increasing the current density, which makes NiMo-based catalysts have broad application prospects in the field of hydrogen production from water electrolysis. However, their performance is significantly affected under the condition of renewable energy fluctuations. The volatility of renewable energy leads to unstable voltage and current during the electrolysis process, which in turn affects the electron transfer process on the catalyst surface and the adsorption / desorption behavior of intermediates. Specifically, the instability of voltage and current may lead to catalyst surface reconstruction and deactivation of active sites, thereby reducing its catalytic activity and stability. In response to the performance degradation of NiMo-based catalysts under renewable energy fluctuations, some studies have attempted to improve their stability and activity by optimizing catalyst structure, introducing additives or performing surface modification. Summary of the invention

[0004] In view of the technical problems described in the background technology, the present invention proposes a NiMo-based catalyst suitable for hydrogen production from alkaline water under the condition of renewable energy fluctuations, namely a Cr, N co-doped nickel molybdate array catalyst. The catalyst effectively improves the activity and stability under unstable voltage and current conditions through specific element doping and array structure design, and provides new ideas and methods for solving the stability problems of NiMo-based catalysts in practical applications. In the future, with the deepening of research and the improvement of technology, the catalyst of the present invention is expected to play an important role in hydrogen production from water electrolysis and other energy conversion and storage fields, and promote the development and application of clean energy technology.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a Cr and N co-doped NiMo array electrode comprises the following steps:

[0007] Step 1: Pre-treat the nickel foam to remove surface pollutants and impurities, and cut the nickel foam into 3 4 cm rectangular blocks were ultrasonically treated with dilute acid solution to remove surface oxides, and then ultrasonically treated with ethanol or acetone to remove surface oil stains. Finally, the surface of the nickel foam was rinsed with deionized water and dried for later use.

[0008] Step 2: Prepare Ni(NO3)2·6H2O, (NH4)6Mo7O 24 ·4H2O and CrCl3·6H2O precursor reaction solution, take 35 mL and place it in a 50 mL reactor liner, then insert a clean rectangular nickel foam upright into the reactor liner. Use the hydrothermal method to in-situ grow the Cr-doped nickel molybdate array precursor on the nickel foam surface prepared in step 1. After the reaction is completed, take out the precursor, rinse it with anhydrous ethanol and deionized water, and dry it for later use;

[0009] Step 3: In a tube furnace, place the Cr-doped nickel molybdate array precursor prepared in step 2 at the downwind port, and place urea at the upwind port. During the reaction, inert gas Ar is slowly blown in. During the heating process, urea decomposes into NH3 to participate in the reaction. After the reaction is completed, the nickel foam electrode taken out is a Cr and N co-doped NiMo array electrode.

[0010] In the above technical solution, in step 1, the dilute acid used is a commonly used laboratory acid solution such as hydrochloric acid, nitric acid or sulfuric acid, and the dilute acid concentration is 0.05-0.15 mol L -1 The ultrasonic time is 10-30 min.

[0011] In the above technical solution, in step 2, Ni(NO3)2·6H2O, (NH4)6Mo7O 24 The molar concentration ratio of ·4H2O and CrCl3·6H2O is 40:10:1 to 40:10:5, and the concentration of Ni(NO3)26H2O is 40 mmol L -1 .

[0012] In the above technical solution, in step 2, the temperature of the hydrothermal reaction is 150°C and the reaction time is 5-10h.

[0013] In the above technical solution, in step 3, the heating rate of the tubular furnace is 3-5°C min -1 , raise the temperature to 400℃, maintain for 2 h, and then cool down naturally.

[0014] An application of a Cr and N co-doped NiMo array catalyst is as follows:

[0015] The electrocatalytic hydrogen evolution performance was tested using a three-electrode system, wherein a NiMo array electrode prepared by the above preparation method was used as a working electrode, a carbon rod was used as a counter electrode, a Hg / HgO electrode was used as a reference electrode, and a KOH solution was used as an electrolyte solution.

[0016] In the above technical solution: KOH concentration is 1 mol L -1 .

[0017] In the above technical solution: the hydrogen evolution performance, electron transport performance and fluctuation stability of the Cr and N co-doped NiMo array electrode are significantly better than those of the undoped initial NiMo array catalytic electrode.

[0018] Beneficial effects:

[0019] 1. In the Cr and N co-doped NiMo array electrode, compared with the undoped initial NiMo array electrode, the incorporation of Cr changes the micromorphology of the columnar structure, increases the specific surface area, exposes more active sites, and has the effect of maintaining the hydrogen evolution stability of the NiMo catalyst under fluctuating conditions. The incorporation of N effectively improves the electron transfer efficiency in the process of hydrogen evolution by water electrolysis. The two together improve the activity and stability of hydrogen production by electrocatalytic water decomposition.

[0020] 2. Through Cr and N co-doping and array structure design, the catalyst of the present invention can still maintain high activity and stability under renewable energy fluctuation conditions.

[0021] 3. The catalyst of the present invention is not only applicable to the field of hydrogen production by water electrolysis, but can also be expanded to other energy conversion and storage fields that require efficient and stable electrocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 This is a scanning electron microscopic image of the Cr and N co-doped NiMo array electrode prepared in the present invention.

[0023] Attached Figure 2 This is the X-ray diffraction spectrum of the Cr and N co-doped NiMo array electrode prepared by the present invention.

[0024] Attached Figure 3 The linear sweep voltammetric curve of the Cr and N co-doped NiMo array electrode prepared by the present invention.

[0025] Attached Figure 4 This is the electrochemical impedance spectrum of the Cr and N co-doped NiMo array electrode prepared in the present invention.

[0026] Attached Figure 5 This is a diagram of the fluctuating current stability of the Cr and N co-doped NiMo array electrode prepared by the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0028] Embodiment 1:

[0029] ① Cut the nickel foam into 3 4 cm rectangular cube, placed in 0.1 mol L -1 After ultrasonic treatment with HCl solution for 10 min, it was ultrasonically treated with anhydrous ethanol for 10 min. Finally, the surface of the nickel foam was rinsed with deionized water and dried for later use.

[0030] ② Prepare 35 mL of 40 mmol L -1 Ni(NO3)2·6H2O, 10 mmol L -1 (NH4)6Mo7O 24 4H2O and 1 mmol L -1 The precursor solution of CrCl3·6H2O was placed in a 50 mL reactor liner, and then a clean rectangular nickel foam was inserted upright into the reactor liner. The hydrothermal reaction conditions were 150°C for 6 hours.

[0031] Step 3: In a tube furnace, place the Cr-doped nickel molybdate precursor at the downwind port, and a certain amount of urea at the upwind port. During the reaction, inert gas Ar is continuously blown in. The tube furnace is heated at 5°C min -1 The temperature was raised to 400 °C at a rate of 1.5 °C and maintained for 2 h. After the reaction was completed, the nickel foam electrode taken out was a Cr and N co-doped NiMo array catalyst.

[0032] Embodiment 2:

[0033] ① Cut the nickel foam into 3 4 cm rectangular cube, placed in 0.1 mol L -1 After ultrasonic treatment with HCl solution for 20 min, the surface of the nickel foam was ultrasonically treated with anhydrous ethanol for 20 min. Finally, the surface of the nickel foam was rinsed with deionized water and dried for later use.

[0034] ② Prepare 35 mL of 40 mmol L -1 Ni(NO3)2·6H2O, 10 mmol L -1 (NH4)6Mo7O 24 4H2O and 2 mmol L -1The precursor solution of CrCl3·6H2O was placed in a 50 mL reactor liner, and then a clean rectangular nickel foam was inserted upright into the reactor liner. The hydrothermal reaction conditions were 150°C for 6 hours.

[0035] Step 3: In a tube furnace, place the Cr-doped nickel molybdate precursor at the downwind port, and a certain amount of urea at the upwind port. During the reaction, inert gas Ar is continuously blown in. The tube furnace is heated at 5 °C min -1 The temperature was raised to 400 °C at a rate of 1.5 °C and maintained for 2 h. After the reaction was completed, the nickel foam electrode taken out was a Cr and N co-doped NiMo array catalyst.

[0036] Embodiment three:

[0037] ① Cut the nickel foam into 3 4 cm rectangular cube, placed in 0.1 mol L -1 After ultrasonic treatment with HCl solution for 20 min, the surface of the nickel foam was ultrasonically treated with anhydrous ethanol for 20 min. Finally, the surface of the nickel foam was rinsed with deionized water and dried for later use.

[0038] ② Prepare 35 mL of 40 mmol L -1 Ni(NO3)2·6H2O, 10 mmol L -1 (NH4)6Mo7O 24 4H2O and 3 mmol L -1 The precursor solution of CrCl3·6H2O was placed in a 50 mL reactor liner, and then a clean rectangular nickel foam was inserted upright into the reactor liner. The hydrothermal reaction conditions were 150°C for 6 hours.

[0039] Step 3: In a tube furnace, place the Cr-doped nickel molybdate precursor at the downwind port, and a certain amount of urea at the upwind port. During the reaction, inert gas Ar is continuously blown in. The tube furnace is heated at 5 °C min -1 The temperature was raised to 400 °C at a rate of 1.5 °C and maintained for 2 h. After the reaction was completed, the nickel foam electrode taken out was a Cr and N co-doped NiMo array catalyst.

[0040] Experimental results:

[0041] In the embodiment of the present invention, Cr and N co-doped NiMo array electrodes were prepared. From the scanning electron microscopy images, it can be seen that the columnar array structure on the surface of the nickel foam is uniformly distributed on the surface of the nanocolumns. The secondary structure of nanosheets is shown in the attached figure. Figure 1 The X-ray diffraction spectrum shows (see Appendix Figure 2As shown in Figure 3, the diffraction signals of the Cr and N co-doped NiMo array electrode are basically consistent with those of the undoped NiMo array electrode, indicating that doping does not change the physical phase of the NiMo material.

[0042] The Cr and N co-doped NiMo array electrode prepared in the embodiment of the present invention has a three-dimensional porous open structure and can be directly used as a working electrode for hydrogen production in alkaline water electrolysis without the need for a spraying electrode preparation process of powdered nanomaterials. The hydrogen evolution performance of the prepared electrode was evaluated using a three-electrode test system. 1 mol L -1 KOH solution was used as electrolyte solution, carbon rod as counter electrode, Hg / HgO as reference electrode, and the prepared NiMo-based electrode as working electrode. Figure 3 As shown in Figure 2, the Cr and N co-doped NiMo-based electrode has better hydrogen evolution activity than the undoped NiMo-based electrode. Figure 4 As shown in Figure 2, Cr and N co-doped NiMo-based electrodes also have a faster electron transfer rate during the hydrogen evolution reaction. Figure 5 As shown, the Cr and N co-doped NiMo electrode has a more stable fluctuating current stability.

[0043] The present invention does not elaborate on some of the common technologies of those skilled in the art. The above-described embodiments are only descriptions of preferred implementations of the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementations described. Without departing from the design spirit of the present invention, various modifications and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A Cr and N co-doped NiMo array electrode, characterized in that: Prepared according to the following steps: Step 1: Pre-treat the nickel foam to remove surface pollutants and impurities, and cut the nickel foam into 3 4 cm rectangular blocks were treated with dilute acid solution to remove surface oxides, then with ethanol or acetone to remove surface oil, and finally the surface of the nickel foam was rinsed with deionized water and dried for later use; Step 2: Prepare Ni(NO3)2·6H2O, (NH4)6Mo7O 24 ·4H2O and CrCl3·6H2O precursor reaction solution, take 35 mL and place it in a 50 mL reactor liner, then insert a clean rectangular nickel foam upright into the reactor liner, and in situ grow Cr-doped nickel molybdate array precursor on the surface of the nickel foam prepared in step 1 by hydrothermal method, take out the precursor after the reaction is completed, rinse it with anhydrous ethanol and deionized water, and dry it for use; Step 3: In a tubular furnace, the Cr-doped nickel molybdate array precursor prepared in step 2 is placed at the downwind port, and urea is placed at the upwind port. During the reaction, inert gas Ar is slowly and continuously blown in, and the temperature is raised. Urea is decomposed into NH3 to participate in the reaction. After the reaction is completed, the nickel foam electrode removed is a Cr and N co-doped NiMo array electrode.

2. A method for preparing a Cr and N co-doped NiMo array electrode, characterized in that: The steps include: Step 1: Pre-treat the nickel foam to remove surface pollutants and impurities, and cut the nickel foam into 3 4 cm rectangular blocks were ultrasonically treated with a dilute acid solution to remove surface oxides, then ultrasonically treated with ethanol or acetone to remove surface oil stains, and finally the surface of the nickel foam was rinsed with deionized water and dried for later use; Step 2: Prepare Ni(NO3)2·6H2O, (NH4)6Mo7O 24 ·4H2O and CrCl3·6H2O precursor reaction solution, take 35 mL and place it in a 50 mL reactor liner, then insert a clean rectangular nickel foam upright into the reactor liner, and in situ grow Cr-doped nickel molybdate array precursor on the surface of the nickel foam prepared in step 1 by hydrothermal method, take out the precursor after the reaction is completed, rinse it with anhydrous ethanol and deionized water, and dry it for use; Step 3: In a tubular furnace, the Cr-doped nickel molybdate array precursor prepared in step 2 is placed at the downwind port, and urea is placed at the upwind port. During the reaction, inert gas Ar is slowly and continuously blown in. The temperature is heated and maintained for a certain period of time. Urea is decomposed into NH3 to participate in the reaction. After the reaction is completed, the nickel foam electrode taken out is a Cr and N co-doped NiMo array electrode.

3. The method for preparing a Cr and N co-doped NiMo array electrode according to claim 2, characterized in that: In step 1, the dilute acid used is hydrochloric acid, nitric acid or sulfuric acid, and the dilute acid concentration is 0.05-0.15 mol L -1 The ultrasound time is 10-30min.

4. The method for preparing a Cr and N co-doped NiMo array electrode according to claim 2, characterized in that: In step 2, Ni(NO3)2·6H2O, (NH4)6Mo7O 24 The molar concentration ratio of ·4H2O and CrCl3·6H2O is 40:10:1 to 40:10:5, and the concentration of Ni(NO3)2·6H2O is 40 mmol L -1 .

5. The method for preparing a Cr and N co-doped NiMo array electrode as claimed in claim 2, characterized in that: In step 2, the temperature of the hydrothermal reaction in the hydrothermal method is 150 °C, and the reaction time is 5-10 h.

6. The method for preparing a Cr and N co-doped NiMo array electrode according to claim 2, characterized in that: In step 3, the heating rate of the tube furnace is 3-5℃ min -1 , heat to 400℃, maintain for 2 h, and then cool down naturally.

7. The use of a Cr and N co-doped NiMo array electrode according to any one of claims 1 to 6, characterized in that: The electrocatalytic hydrogen evolution performance was tested using a three-electrode system, in which the Cr and N co-doped NiMo array electrode was the working electrode, the carbon rod was the counter electrode, the Hg / HgO electrode was the reference electrode, and 1 M KOH solution was the electrolyte solution.

8. The use of a Cr and N co-doped NiMo array electrode as claimed in claim 7, characterized in that: The hydrogen evolution performance, electron transport performance and fluctuation stability of the Cr and N co-doped NiMo array electrode are better than those of the undoped initial NiMo array catalytic electrode.

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