CN113604839B

CN113604839B - Method for preparing metal oxide passivated nickel/nickel oxide in-situ electrode

Info

Publication number: CN113604839B
Application number: CN202110950897.4A
Authority: CN
Inventors: 黄妞; 李佳乐; 骆禅; 杨柳
Original assignee: China Three Gorges University CTGU
Current assignee: China Three Gorges University CTGU
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2022-08-05
Anticipated expiration: 2041-08-18
Also published as: CN113604839A

Abstract

The invention provides a preparation method of a metal oxide passivated nickel/nickel oxide in-situ electrode. Preparing a precursor solution containing nickel/chromium (molybdenum) ions and oxides or hydroxides of nickel/chromium (molybdenum), attaching the precursor solution to the surface of foam Nickel (NF), and applying a reduction potential in a specific electrolyte for reduction by using an electrochemical reduction method to partially reduce nickel oxide or nickel hydroxide in the precursor substance attached to the surface of the foam Nickel (NF) into metallic nickel to obtain a chromium oxide (molybdenum oxide) passivated nickel/nickel oxide in-situ electrode. The technical scheme of the invention has the advantages of low cost of the required raw materials, simple operation, short time consumption, less environmental pollution and the like; the prepared chromium oxide (molybdenum oxide) passivated nickel/nickel oxide in-situ electrode shows excellent catalytic activity as a bifunctional electrocatalyst for Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER), and has good prospect of being applied to electrocatalytic decomposition of water.

Description

Method for preparing metal oxide passivated nickel/nickel oxide in-situ electrode

Technical Field

The invention relates to preparation of a multi-component multifunctional material, and belongs to the field of electrocatalysis and energy conversion materials and devices.

Background

The method for producing hydrogen by electrolyzing water has the advantages of rich raw materials, high product purity and the like, and is considered to be one of clean and green hydrogen production methods. However, the high energy barrier of the two half reactions constituting the water electrolysis reaction, the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER), limits and affects the energy conversion efficiency of the electrolysis process and the development of water electrolysis hydrogen production technology, and thus it is required to develop a highly active catalyst to lower the reaction energy barrier. To date, the most efficient electrocatalysts are still noble metal based catalysts, but their large scale application is greatly limited by the prohibitive price and scarce resources. In addition, these catalysts generally exhibit high activity only for one half-reaction and are less active for the other half-reaction. Therefore, the development of a bifunctional non-noble metal compound catalyst with both high HER and OER activity is crucial to achieving efficient electrolyzed water reactions from both cost reduction and process simplification considerations.

Transition metals or their derivatives such as chalcogenides, nitrides and phosphides have been widely used as HER catalysts, while perovskites and transition metal hydroxides/oxides have been widely used as OER catalysts in terms of cost effectiveness, catalytic activity and long-term stability. Nickel-based compounds have proven to be promising electrocatalysts for the catalysis of HER and OER due to their earth-abundant, environmentally friendly and easily regulated electronic structure.

Is inspired byMing GongEt al (Angew. Chem.2015, 127, 12157.) utilization of Cr ₂ O ₃ Passivating Ni/NiO to obtain the HER/OER bifunctional catalyst with high stability and high activity. Group VIB elements in the low spin state (e.g., chromium, molybdenum, tungsten) are reported to exhibit different oxidation states, and their oxides have reversible surface oxygen ion exchange capacity (Nature communications, 2014, 5(1): 1-6.). In addition, Ni-NiO heterojunctions have been reported to optimize the hydrogen adsorption energy, thereby accelerating hydrogen adsorption kinetics (Nature communications, 2014, 5(1): 1-6.).

Accordingly, we intend to prepare chromium oxide (molybdenum oxide) passivated nickel/nickel oxide in situ electrodes using "solution coating + electrochemical reduction". The attached hydroxide is generated into oxide by using a more negative reduction potential, and the nickel oxide or nickel salt is reduced into metallic nickel, and more active sites are exposed; the prepared chromium oxide (molybdenum oxide) -passivated nickel/nickel oxide in-situ electrode is supposed to have high HER and OER electrocatalytic activity and high stability by adjusting the electrochemical reduction time to optimize the proportion of nickel and nickel oxide in the prepared electrode.

Disclosure of Invention

In view of this, the present invention provides a method for preparing a nickel/nickel oxide in-situ electrode passivated by chromium oxide (molybdenum oxide), which comprises the following steps:

(1) preparation of nickel/chromium (molybdenum) (hydr) oxide precursors: dissolving nickel chloride with crystal water removed in a mixed solution of ethanol and glacial acetic acid, adding chromium acetate (molybdenum acetylacetonate) while stirring, then adding a water-ethanol mixed solution, continuously stirring until the solution is clear, placing the solution in a hydrothermal tank, keeping the temperature to form an oxide solution or a hydroxide solution of nickel/chromium (molybdenum), wherein the oxide solution or the hydroxide solution mainly contains nickel/chromium (molybdenum) ions and contains a small amount of nickel/chromium (molybdenum) (the preparation process of the precursor solution comprises the heat preservation process, and no obvious phenomena of hydrolysis, deposition, thickening of the solution, disappearance of the deposition and the like are seen, so that a large amount of nickel/chromium (molybdenum) still exists in an ion form and is not converted into an oxide or a hydroxide, the precursor solution is more similar to a solution rather than a sol), soaking foam Nickel (NF) in the cooled foam nickel, and then taking out and drying the foam nickel.

(2) Electro-reduction: and (3) placing the NF attached with the precursor into a mixed solution of sodium sulfate and boric acid, and performing electro-reduction on the NF for a period of time by using an electrochemical workstation in a constant potential mode. And (3) flushing the surface electrolyte with UP water and drying to obtain the chromium oxide (molybdenum oxide) passivated nickel/nickel oxide in-situ electrode.

Further, in S1, the concentration of nickel chloride is 0.5-1 mol/L, and the molar ratio of chromium acetate to nickel chloride is 1: 0.1-0.3, wherein the concentration of molybdenum acetylacetonate is 1: 0.1 to 0.2 mol/L.

Further, in S1, the first solvent is a mixed solution of ethanol and glacial acetic acid, wherein a volume ratio of ethanol to glacial acetic acid is 1: 0.02-0.04, wherein the second solvent is a water-ethanol mixed solution, and the volume ratio of ethanol to water is 1: 0.03-0.07, wherein the volume ratio of the first solvent to the second solvent is 1: 0.1 to 0.3.

Further, the heat preservation temperature of the hydrothermal box in S1 is 80 ℃, and the heat preservation time is 4 hours.

Further, the drying temperature in S1 and S2 is 70-90 ℃.

Further, the constant potential in S2 is in the range of-1.0 to-2.0V relative to the saturated calomel electrode.

Furthermore, the time in S2 is 200 seconds to 600 seconds.

The invention also relates to the application of the material obtained by the preparation method in HER/OER bifunctional catalytic electrolysis water.

The invention has the following beneficial effects:

1. the Ni and Cr (Mo) elements in the precursor solution reach molecular level mixing, so that for the catalytic performance of a subsequently formed heterojunction catalyst, the particle size of the product is favorably refined, and more active areas are favorably exposed to improve the catalytic performance of the material; on the other hand, the uniform dispersion of Ni, nickel oxide and chromium oxide phases (molybdenum oxide phases) in the nickel/nickel oxide in-situ electrode passivated by subsequently generated chromium oxide is facilitated, the nickel/nickel oxide heterojunction with richer interface is obtained, the good coating of the chromium oxide (molybdenum oxide) phase is realized, and the synergistic improvement of the electrocatalytic activity and stability of HER and OER is facilitated.

2. And (3) placing the NF attached with the precursor into a mixed solution of sodium sulfate and boric acid, and performing electro-reduction on the NF for a period of time by using an electrochemical workstation in a constant potential mode. By utilizing an electrochemical reduction mechanism, the oxide is more stable than the hydroxide under more negative potential, so that phases of chromium oxide (molybdenum oxide) and nickel oxide can be obtained, and high-valence nickel ions, nickel oxide and nickel hydroxide can be reduced into zero-valence metallic nickel.

Drawings

Fig. 1 shows HER linear voltammetry scans and OER linear voltammetry scans measured on samples prepared in example 1, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 2 shows HER linear voltammetry scans and OER linear voltammetry scans measured on the samples prepared in example 2, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 3 shows HER linear voltammetry scans and OER linear voltammetry scans measured on samples prepared in example 3, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 4 shows HER linear voltammetry scans and OER linear voltammetry scans measured on the samples prepared in example 4, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 5 shows HER linear voltammetry scans and OER linear voltammetry scans measured on samples prepared in example 5, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 6 shows HER linear voltammetry scans and OER linear voltammetry scans measured on samples prepared in example 6, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 7 shows HER linear voltammetry scans and OER linear voltammetry scans measured on the samples prepared in example 7, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 8 shows HER linear voltammetry scans and OER linear voltammetry scans for the samples prepared in example 8, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 9 shows HER linear voltammetry scans and OER linear voltammetry scans measured on the samples prepared in example 9, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Fig. 10 is a graph of HER linear voltammetry scans and OER linear voltammetry scans measured on samples prepared in example 10, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

Figure 11 is a graph of HER linear voltammetric sweep and OER linear voltammetric sweep of the sample prepared in example 11, wherein a is HER linear voltammetric sweep (LSV) and b is OER linear voltammetric sweep (LSV).

Fig. 12 shows HER linear voltammetry scans and OER linear voltammetry scans measured on samples prepared in example 12, wherein a is HER linear voltammetry scan (LSV) and b is OER linear voltammetry scan (LSV).

FIG. 13 is an SEM photograph of a sample prepared in example 3, wherein a is a 10000-magnification view and b is a 50000-magnification view.

FIG. 14 is an SEM photograph of a sample prepared in example 5, wherein a is a 10000-magnification view and b is a 20000-magnification view.

FIG. 15 is an SEM photograph of a sample prepared in example 6, wherein a is a 10000-magnification view and b is a 50000-magnification view.

FIG. 16 is an SEM photograph of a sample prepared in example 9, wherein a is a 10000-magnification view and b is a 50000-magnification view.

FIG. 17 is an SEM photograph of a sample prepared in example 11, wherein a is a 10000-magnification view and b is a 50000-magnification view.

FIG. 18 is an SEM photograph of a sample prepared in example 12, wherein a is a 10000-magnification view and b is a 20000-magnification view.

Fig. 19 is an XRD pattern of example 3, example 5, and example 6.

Fig. 20 is an XRD pattern of example 9, example 11, and example 12.

Characterizing conditions

The HER and OER test method in the invention embodiment comprises the following steps: foamed nickel is used as a working electrode, a carbon rod is used as a counter electrode, a saturated Hg/HgO electrode is used as a reference electrode, and the used electrolytes are as follows: 1M KOH aqueous solution, and the scanning speed is 5-10 mV/s. The HER test was performed with nitrogen, and the OER test was performed with oxygen. Oxygen and nitrogen were naturally saturated in 1M aqueous KOH and stirred at 200 rpm during the test. The saturated Hg/HgO electrode was corrected with a reversible hydrogen electrode, and the potentials described hereinafter are all relative to the reversible hydrogen electrode. The electric potential is automatically carried out by using a Shanghai chemical workstation in the LSV testIR-95%) And (6) compensation. An X-ray diffraction (SEM) pattern of the sample was obtained using a SMART LAB-9 type X-ray diffractometer. Scanning electron microscope (XRD) images were acquired using an aspect F50 scanning electron microscope (FEI America).

Example 1

At room temperature, 4.125 g of NiCl ₂ Dissolved in a mixture of 36.5 mL ethanol and 1.2 mL glacial acetic acid, then 1.28 g of chromium acetate is added while stirring, then a mixture of 10 mL ethanol and 0.5 mL water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and then dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. By usingAnd (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.0V, and the time is 600 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 1 is a linear voltammetric scan (LSV) of HER and OER measured on the samples prepared in example 1. As can be seen from FIG. 1 (a), the current density when the electrode passes through the electrode is 10 mA/cm ² When the hydrogen is generated through HER reaction in the alkaline aqueous solution, the corresponding overpotential is 166 mV; as can be seen from FIG. 1 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the oxygen production by the OER reaction in the alkaline aqueous solution is 390 mV.

Example 2

At room temperature, 4.125 g of NiCl ₂ Dissolved in a mixture of 36.5 mL ethanol and 1.2 mL glacial acetic acid, then 1.28 g of chromium acetate is added while stirring, then a mixture of 10 mL ethanol and 0.5 mL water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, and an alternating potential is set, wherein the potential at the first section is-1.0V, the time is 30 seconds, the potential at the second section is + 0.3V, the time is 5 seconds, and the alternating cycle is performed for 40 times. The surface electrolyte was washed off with UP water and dried.

Figure 2 is a graph of HER and OER linear voltammetric scans (LSVs) measured for the samples prepared in example 2. As can be seen from FIG. 2 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to HER reaction in the alkaline aqueous solution is 178 mV; as can be seen from FIG. 2 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the OER reaction in the alkaline aqueous solution is 360 mV.

Example 3

At room temperature, 4.125 g of NiCl ₂ Dissolved in a mixture of 36.5 mL of ethanol and 1.2 mL of glacial acetic acid, and then 1.28 g of chromium acetate was added while stirring, followed by dropwise additionA mixture of 10 mL ethanol and 0.5 mL water was added and stirring was continued until the solution was clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.5V, and the time is 200 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 3 is a linear voltammetric scan (LSV) of HER and OER measured for the samples prepared in example 3. As can be seen from FIG. 3 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 156 mV; as can be seen from FIG. 3 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution is 380 mV.

FIG. 3 is an SEM photograph of example 3 showing that the prepared sample was attached to nickel foam in a lump form, and it was observed that it had pores at a high magnification.

Example 4

At room temperature, 4.125 g of NiCl ₂ Dissolved in a mixture of 36.5 mL ethanol and 1.2 mL glacial acetic acid, then 1.28 g of chromium acetate is added while stirring, then a mixture of 10 mL ethanol and 0.5 mL water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.5V, and the time is 400 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 4 is a linear voltammetric scan (LSV) of HER and OER measured for the samples prepared in example 4. As can be seen from FIG. 4 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² In alkaline aqueous solution, the HER reaction is overpotentialBit 163 mV; as can be seen from FIG. 4 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution was 370 mV.

Example 5

At room temperature, 4.125 g of NiCl ₂ Dissolved in a mixture of 36.5 mL ethanol and 1.2 mL glacial acetic acid, then 1.28 g of chromium acetate is added while stirring, then a mixture of 10 mL ethanol and 0.5 mL water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and then dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.5V, and the time is 600 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 5 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 5. As can be seen from FIG. 5 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 174 mV; as can be seen from FIG. 5 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution is 350 mV.

FIG. 5 is an SEM photograph of example 5, showing that the prepared sample was attached to nickel foam in a lump form, and was observed to be in a small particle state at a high magnification.

Example 6

At room temperature, 4.125 g of NiCl ₂ Dissolved in a mixture of 36.5 mL ethanol and 1.2 mL glacial acetic acid, then 1.28 g of chromium acetate is added while stirring, then a mixture of 10 mL ethanol and 0.5 mL water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. Pairing the treated N with an electrochemical workstationAnd F, performing electroreduction, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-2.0V, and the time is 600 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 6 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 6. As can be seen from FIG. 6 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction solution is alkaline, the overpotential corresponding to HER reaction is 168 mV; as can be seen from FIG. 6 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution was 320 mV.

FIG. 6 is an SEM photograph of example 6 showing that the prepared sample adhered to nickel foam and was observed to be spherical at a high magnification.

FIG. 19 is an XRD pattern of examples 3, 5 and 6, and compared with a standard PDF card, the three strongest peaks of the pattern are Ni peaks, and the crystallinity of the generated nickel oxide and chromium oxide is not high, but weak.

Example 7

At room temperature, 2.475 g of NiCl were added ₂ Dissolved in a mixture of 21.99 mL of ethanol and 0.72 mL of glacial acetic acid, then 1.099 g of molybdenum acetylacetonate is added while stirring, then a mixture of 6 mL of ethanol and 0.3 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.0V, and the time is 600 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 7 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 7. As can be seen from FIG. 7 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out in an alkaline aqueous solution, the overpotential corresponding to the HER reaction is 163 mV; as can be seen from FIG. 7 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In alkaline aqueous solution, the OER reaction corresponds toThe overpotential was 370 mV.

Example 8

At room temperature, 2.475 g of NiCl were added ₂ Dissolved in a mixture of 21.99 mL of ethanol and 0.72 mL of glacial acetic acid, then 1.099 g of molybdenum acetylacetonate is added while stirring, then a mixture of 6 mL of ethanol and 0.3 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the first-stage potential of the alternating potential is set to be-1.0V for 30 seconds, the second-stage potential is set to be + 0.3V for 5 seconds, and the cycle is performed for 40 times. The surface electrolyte was washed off with UP water and dried.

Figure 8 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 8. As can be seen from FIG. 8 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 174 mV; as can be seen from FIG. 8 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² The overpotential for the OER reaction in the alkaline aqueous solution is 390 mV.

Example 9

At room temperature, 2.475 g of NiCl were added ₂ Dissolved in a mixture of 21.99 mL of ethanol and 0.72 mL of glacial acetic acid, then 1.099 g of molybdenum acetylacetonate is added while stirring, then a mixture of 6 mL of ethanol and 0.3 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.5V, and the time is 200 seconds. The surface electrolyte was washed off with UP water and dried.

FIG. 9 is the preparation of example 9HER and OER linear voltammetric scans (LSV) measured on the samples of (a). As can be seen from FIG. 9 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 155 mV; as can be seen from FIG. 9 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² The overpotential corresponding to the OER reaction in the alkaline aqueous solution is 350 mV.

FIG. 16 is an SEM photograph of example 9 showing that the prepared sample adhered to nickel foam and was observed to be spherical at a high magnification.

Example 10

At room temperature, 2.475 g of NiCl were added ₂ Dissolved in a mixture of 21.99 mL of ethanol and 0.72 mL of glacial acetic acid, then 1.099 g of molybdenum acetylacetonate is added while stirring, then a mixture of 6 mL of ethanol and 0.3 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.5V, and the time is 400 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 10 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 10. As can be seen from FIG. 10 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out in an alkaline aqueous solution, the overpotential corresponding to the HER reaction is 175 mV; as can be seen from FIG. 10 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution was 330 mV.

Example 11

At room temperature, 2.475 g of NiCl were added ₂ Dissolved in a mixture of 21.99 mL of ethanol and 0.72 mL of glacial acetic acid, then 1.099 g of molybdenum acetylacetonate is added while stirring, then a mixture of 6 mL of ethanol and 0.3 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. Sealing, maintaining at 80 deg.C for 4 hr, cooling, and adding foamed nickel(NF) immersion for ten minutes followed by drying at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-1.5V, and the time is 600 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 11 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 11. As can be seen from FIG. 11 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 139 mV; as can be seen from FIG. 11 (b), the current density when the electrode passes through the electrode was 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution is 350 mV.

FIG. 17 is an SEM photograph of example 11 showing that the prepared sample adhered to nickel foam and was observed to be spherical at a high magnification.

Example 12

At room temperature, 2.475 g of NiCl were added ₂ Dissolved in a mixture of 21.99 mL of ethanol and 0.72 mL of glacial acetic acid, then 1.099 g of molybdenum acetylacetonate is added while stirring, then a mixture of 6 mL of ethanol and 0.3 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hot water oven at 80 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and subsequently dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-2.0V, and the time is 600 seconds. The surface electrolyte was washed off with UP water and dried.

Figure 12 is a HER and OER linear voltammetric scan (LSV) measured on the samples prepared in example 12. As can be seen from FIG. 12 (a), the current density when the electrode passes through the electrode was 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 150 mV; FIG. 12 (b) shows that the current density when the electrode passes through the electrode is 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution is 350 mV.

FIG. 18 is an SEM photograph of example 12 showing that the prepared sample adhered to nickel foam and was observed to be spherical at a high magnification.

FIG. 20 is an XRD pattern of examples 3, 5 and 6, comparing with standard PDF card, the three strongest peaks are Ni peaks, and the crystallinity of nickel oxide and molybdenum oxide is not high and the diffraction peak is not very weak.

Example 13

At room temperature, 0.825 g of NiCl ₂ Dissolved in a mixture of 7.3 mL of ethanol and 0.24 mL of glacial acetic acid, then 0.366 g of molybdenum acetylacetonate is added while stirring, then a mixture of 2 mL of ethanol and 0.1 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hydrothermal chamber at 120 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and then dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. And (3) performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, a platinum sheet is used as a counter electrode, the potential is set to be-3.0V, and the time is 1800 seconds. The surface electrolyte was washed off with UP water and dried.

When the current density of the electrode passing through is 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 210 mV; when the current density of the electrode passing through is 10 mA/cm ² The overpotential for the OER reaction in the alkaline aqueous solution is 300 mV.

Example 14

At room temperature, 0.825 g of NiCl ₂ Dissolved in a mixture of 7.3 mL of ethanol and 0.24 mL of glacial acetic acid, then 0.146 g of chromium acetate is added while stirring, then a mixture of 2 mL of ethanol and 0.1 mL of water is added dropwise, and stirring is continued until the solution is clear to form a solution. It was then sealed and incubated in a hydrothermal chamber at 120 ℃ for 4 hours, and after cooling, Nickel Foam (NF) was immersed for ten minutes and then dried at 80 ℃. 7.102 g of sodium sulfate and 3.0915 g of boric acid were weighed out to prepare 100 mL of an electrolyte, and the solvent was UP water. Performing electric reduction on the treated NF by using an electrochemical workstation, wherein a calomel electrode is used as a reference electrode, andthe electrode was made of platinum sheet, and the potential was set at-3.0V for 1800 seconds. The surface electrolyte was washed off with UP water and dried.

When the current density of the electrode passing through is 10 mA/cm ² When the reaction is carried out, the overpotential corresponding to the HER reaction in the alkaline aqueous solution is 203 mV; when the current density of the electrode passing through is 10 mA/cm ² In this case, the overpotential for the OER reaction in the aqueous alkaline solution is 300 mV.

Claims

1. A preparation method of a metal oxide passivated nickel/nickel oxide in-situ electrode is characterized by comprising the following steps:

s1, preparing an oxide or hydroxide precursor of nickel/chromium: dissolving nickel chloride with crystal water removed in a first solvent, adding chromium acetate while stirring, then adding a second solvent, continuously stirring until the solution is clear, placing the solution in a hydrothermal box, keeping the temperature at 80-120 ℃, keeping the temperature for 4 hours to form a solution containing nickel/chromium oxide or hydroxide, cooling, then soaking foamed nickel in the solution, and then taking out and drying;

the first solvent is a mixed solution of ethanol and glacial acetic acid, wherein the volume ratio of the ethanol to the glacial acetic acid is 1: 0.02-0.04, wherein the second solvent is a water-ethanol mixed solution, and the volume ratio of ethanol to water is 1: 0.03-0.07, wherein the volume ratio of the first solvent to the second solvent is 1: 0.1-0.3, the concentration of nickel chloride is 0.5-1 mol/L, and the molar ratio of chromium acetate to nickel chloride is 1: 0.1 to 0.3;

s2, electroreduction: and (2) placing the NF attached with the precursor in an electrolyte of sodium sulfate and boric acid, performing electro-reduction on the NF for a period of time by using an electrochemical workstation in a constant potential mode, wherein the constant potential is in a range of-1.0 to-2.0V relative to the saturated calomel electrode, flushing the electrolyte on the surface by UP water, and drying to obtain the chromium oxide passivated nickel/nickel oxide in-situ electrode.

2. The method of claim 1, wherein the drying in S1 and S2 is 70-90 ℃.

3. The method for preparing the metal oxide passivated nickel/nickel oxide in-situ electrode according to claim 1, wherein the time in S2 is 200 seconds to 600 seconds.

4. The method of claim 1, wherein the chromium acetate is replaced by molybdenum acetylacetonate, and the molar ratio of molybdenum acetylacetonate to nickel chloride is 1: 0.1-0.2, the obtained product is a nickel/nickel oxide in-situ electrode passivated by molybdenum oxide.