A Ni-NiO / Fe(OH)3 / CC bifunctional catalyst and its preparation method and application

Abstract

The present invention belongs to the field of catalyst preparation technology, and specifically relates to a Ni-NiO / Fe(OH)3 / CC bifunctional catalyst and its preparation method and application. The present invention uses carbon cloth as a substrate and prepares Ni-NiO / Fe(OH)3 / CC composed of polymeric nanoparticles with interparticle pores by a method combining electrodeposition and chemical precipitation. The catalyst has multiple active components, and the components are tightly combined to form a unique network structure, exposing more active sites, improving electrical conductivity and having high-intensity stability. In addition, through the synergistic effect between different metals, the adsorption Gibbs free energy of the intermediate product can be significantly reduced, thereby improving the catalytic activity of the catalyst material, making it exhibit lower overpotential and faster kinetics, and having good stability. The preparation method of the present invention is simple, the raw materials are easily available, the cost is low, and it is easy to realize industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and in particular relates to a Ni-NiO / Fe(OH)3 / CC bifunctional catalyst and a preparation method and application thereof. Background Art

[0002] Considering the current situation, the vast majority of contemporary energy still comes from fossil fuels. However, the depletion and utilization of non-renewable fossil fuels have severely hampered the sustainable development of human society. Hydrogen, with its advantages such as high energy density, high fuel efficiency, and zero carbon emissions, is widely considered a potential energy carrier for future sustainable energy systems. Current industrial hydrogen production methods primarily utilize fossil fuels, industrial byproducts, and water electrolysis. Water electrolysis, with its primary raw material being H2O, offers simple technology, widespread availability, and low energy consumption, making it a truly sustainable and pollution-free process. Therefore, it is currently the most promising hydrogen production technology.

[0003] Currently, some commercial water-splitting catalysts are primarily based on precious metals (Pt / C and IrO2 / RuO2). However, their inherent scarcity, instability, and high cost significantly limit their application in catalytic water splitting. Consequently, non-precious metal catalysts have attracted widespread attention, and the search for high-performance non-precious metal catalysts has become a research hotspot. Currently, a common modification method involves combining highly dispersed metals with non-precious metal oxides to prepare composite catalysts with heterojunctions, or directly using different transition metal oxides to form heterojunction interfaces to promote water splitting on the oxides. This method has the advantages of increasing the number of active sites and effectively promoting water splitting. Although a large number of non-precious metal composite catalysts have been developed in recent years, few exhibit high catalytic activity for both hydrogen and oxygen evolution, resulting in a limited number of catalysts that can be effectively applied to catalyze the overall hydrolysis reaction. Therefore, the preparation of bifunctional non-precious metal catalysts for overall hydrolysis is a challenging task. Summary of the Invention

[0004] The present invention aims to address the above-mentioned problems existing in the prior art and discloses a bifunctional catalyst suitable for full hydrolysis. The catalyst has multiple active components, and there is a synergistic effect between the multiple active components. The components are closely combined to form a unique structure, thereby exposing more active sites, improving conductivity and having high strength stability. The specific technical solution is as follows:

[0005] In a specific embodiment, the present invention provides a method for preparing a Ni-NiO / Fe(OH)3 / CC bifunctional catalyst, which specifically comprises the following steps:

[0006] (1) Soaking the carbon cloth in a nitric acid solution (16 mol / L) to remove impurities, then placing the carbon cloth in acetone, ethanol, and deionized water for ultrasonic cleaning, and drying the carbon cloth after cleaning to obtain the pretreated carbon cloth;

[0007] (2) using the carbon cloth pretreated in step (1) as a working electrode, a carbon rod electrode as a counter electrode, and a Hg / HgO electrode as a reference electrode; connecting the circuit, placing the electrode in an electrolytic cell and performing electrochemical deposition; after the electrodeposition is completed, repeatedly rinsing with deionized water, and drying to obtain a Ni / NiO / CC electrode;

[0008] (3) Immersing the Ni / NiO / CC electrode prepared in step (2) in Fe(NO3)3 solution, dropping KOH solution, allowing to react, and then vacuum drying to obtain a Ni-NiO / Fe(OH)3 / CC catalyst.

[0009] The drying temperature in step (1) is 60°C.

[0010] The electrolyte in the electrolytic cell in step (2) is 20mmoL / L Ni(CH3COOH)2.

[0011] The conditions of the electrochemical deposition in step (2) are: deposition potential of -3V to -1.5V, deposition time of 15 to 30min; the electrochemical deposition is performed once or multiple times.

[0012] The concentration of the Fe(NO3)3 solution in step (3) is 0.25-1.25 mmoL / L.

[0013] The concentration of the KOH solution in step (3) is 1 mol / L, and the volume ratio of the Fe(NO3)3 solution to the KOH solution is 3 to 5:1.

[0014] The standing reaction time in step (3) is 4 to 6 hours.

[0015] The vacuum drying temperature in step (3) is 50-70°C.

[0016] In a specific embodiment, the present invention provides a Ni-NiO / Fe(OH)3 / CC catalyst prepared by the preparation method described above.

[0017] In a specific embodiment, the present invention provides the use of the Ni-NiO / Fe(OH)3 / CC catalyst described above in the field of perhydrolysis.

[0018] Furthermore, the Ni-NiO / Fe(OH)3 / CC catalyst can perform oxygen evolution reaction and / or hydrogen evolution reaction.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention uses carbon cloth as a substrate and prepares Ni-NiO / Fe(OH)3 / CC composed of polymeric nanoparticles with interparticle pores through a method combining electrodeposition and chemical precipitation. The catalyst has multiple active components, and the components are tightly combined to form a unique network structure, exposing more active sites, which is conducive to the penetration of electrolyte into the electrode, improving the conductivity and having high-strength stability. In addition, through the synergistic effect between different metals, the adsorption Gibbs free energy of the intermediate product can be significantly reduced, thereby improving the catalytic activity of the catalyst material, making it exhibit lower overpotential and faster kinetics, and having good stability. It has high bifunctional electrocatalytic activity and can be directly applied to full hydrolysis electrocatalysts. The preparation method of the present invention is simple, the raw materials are easily available, the cost is low, and it is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 is the SEM image of Ni-NiO / Fe(OH)3 / CC catalyst;

[0023] Figure 2 is the XRD pattern of Ni-NiO / Fe(OH)3 / CC catalyst;

[0024] Figure 3 is the FT-IR spectrum of Ni-NiO / Fe(OH)3 / CC catalyst;

[0025] Figure 4 is the electrochemical performance diagram (LSV) of the oxygen evolution reaction;

[0026] Figure 5 This is the oxygen evolution reaction stability test diagram of Ni-NiO / Fe(OH)3 / CC catalyst (it);

[0027] Figure 6 is the electrochemical performance diagram (LSV) of the hydrogen evolution reaction;

[0028] Figure 7 is the stability test diagram of hydrogen evolution reaction (it);

[0029] Figure 8 is the electrochemical performance diagram (LSV) of the complete hydrolysis reaction;

[0030] Figure 9 It is the stability test diagram of the complete hydrolysis reaction (it). DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only intended to illustrate and explain the present invention and are not intended to limit the present invention. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0032] Example 1

[0033] (1) Pretreatment of carbon cloth: In order to make the carbon cloth more hydrophilic and effectively remove impurities on the surface of the carbon cloth, the carbon cloth needs to be pretreated. First, the carbon cloth is soaked in HNO3 solution (16 mol / L) for 24 h, and then the carbon cloth is placed in acetone, ethanol and deionized water for ultrasonic cleaning. After cleaning, it is placed in an environment of 60°C for drying.

[0034] (2) Preparation of Ni / NiO / CC electrode: The carbon cloth, carbon rod electrode and Hg / HgO electrode pretreated in step (1) were used as working electrode, counter electrode and reference electrode respectively; the circuit was connected and placed in an electrolytic cell containing 20 mmol / L Ni(CH3COOH)2 electrolyte, and electrochemical deposition was performed at a voltage of -3 V for 30 min. After the electrodeposition was completed, the electrode was repeatedly rinsed with deionized water and dried at 60°C to obtain a Ni / NiO / CC electrode.

[0035] (3) Preparation of Ni-NiO / Fe(OH)3 / CC catalyst: The Ni / NiO / CC electrode prepared in step (2) was immersed in 30 mL of 0.75 mmol / L Fe(NO3)3 solution, 10 mL of 1 M KOH solution was added dropwise, and the mixture was allowed to stand for 4 hours; the mixture was dried in a vacuum oven at 60°C to obtain the Ni-NiO / Fe(OH)3 / CC catalyst.

[0036] The prepared Ni-NiO / Fe(OH)3 / CC catalyst was analyzed by scanning electron microscopy (SEM). Figure 1 is the SEM image of Ni-NiO / Fe(OH)3 / CC catalyst; Figure 1 The morphology of Ni-NiO / Fe(OH)3 / CC is a network structure composed of polymeric nanoparticles with interparticle pores. This network structure facilitates better electrolyte penetration into the electrode, improving conductivity and high strength stability.

[0037] Furthermore, the prepared Ni-NiO / Fe(OH)3 / CC catalyst was subjected to X-ray diffraction (XRD) analysis. Figure 2is the XRD pattern of Ni-NiO / Fe(OH)3 / CC catalyst; Figure 2 The characteristic peaks of Fe(OH)3 and Ni can be clearly seen, indicating that the prepared materials are mainly Fe(OH)3 and Ni (JCPDS card numbers are 46-1436 and 01-1258, respectively). Due to the low crystallinity of NiO, no obvious characteristic peaks belonging to NiO can be observed in the XRD pattern of the Ni-NiO / Fe(OH)3 / CC catalyst. The prepared Ni-NiO / Fe(OH)3 / CC catalyst was further analyzed by Fourier transform infrared spectroscopy (FT-IR). Figure 3 is the FT-IR graph of Ni-NiO / Fe(OH)3 / CC catalyst; Figure 3 It can be clearly observed at 500 cm -1 Stretching vibrations belonging to Ni-O appeared on the left and right, which confirmed the presence of NiO in the composite catalyst.

[0038] Example 2

[0039] Different Ni-NiO / Fe(OH)3 / CC catalysts were prepared using a preparation method basically the same as that in Example 1. The only difference from Example 1 was that the concentrations of the Fe(NO3)3 solution added in step (3) were replaced with 0.25mmoL / L, 0.5mmoL / L, 0.1mmoL / L and 1.25mmoL / L, respectively.

[0040] Example 3

[0041] (1) Pretreatment of carbon cloth: First, soak the carbon cloth in HNO3 solution (16 mol / L) for 20 h, then place the carbon cloth in acetone, ethanol and deionized water for ultrasonic cleaning, and then place it in an environment of 60 °C for drying after cleaning.

[0042] (2) Preparation of Ni / NiO / CC electrode: The carbon cloth, carbon rod electrode and Hg / HgO electrode pretreated in step (1) were used as working electrode, counter electrode and reference electrode respectively; the circuit was connected and placed in an electrolytic cell containing 20 mmol / L Ni(CH3COOH)2 electrolyte, and electrochemical deposition was performed at -3 V and -1.5 V voltages for 15 min respectively. After the electrodeposition was completed, the electrodes were repeatedly rinsed with deionized water and dried at 60°C to obtain Ni / NiO / CC electrodes.

[0043] (3) Preparation of Ni-NiO / Fe(OH)3 / CC catalyst: The Ni / NiO / CC electrode prepared in step (2) was immersed in 50 mL of 0.75 mmol / L Fe(NO3)3 solution, 10 mL of 1 M KOH solution was added dropwise, and the mixture was allowed to stand for 6 hours; the mixture was dried in a vacuum oven at 70°C to obtain the Ni-NiO / Fe(OH)3 / CC catalyst.

[0044] Comparative Example 1

[0045] The Ni / NiO / CC electrode prepared in Example 1 is used as Comparative Example 1.

[0046] Comparative Example 2

[0047] The carbon cloth pretreated in Example 1 was placed in 30 mL of 0.75 mmol / L Fe(NO3)3 solution, 10 mL of 1M KOH solution was added dropwise, and the mixture was allowed to stand for 4 hours. Finally, the mixture was dried in a vacuum oven at 60°C to obtain a Fe(OH)3 / CC catalyst.

[0048] Application Example 1

[0049] In this application example, a traditional three-electrode system was selected to measure the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance of the electrocatalysts prepared in the examples. A 1M KOH (pH = 14) solution was used as the electrolyte, the Ni-NiO / Fe(OH)3 / CC prepared in Example 1, the catalysts prepared in Comparative Example 1 and Comparative Example 2 were used as working electrodes, a carbon rod electrode was used as the counter electrode, and a Hg / HgO electrode was used as the reference electrode. The electrochemical properties of the materials were measured by linear voltammetry (LSV), and the stability of the materials was tested by chronoamperometry.

[0050] The oxygen evolution reaction test of the material was carried out in 1M KOH (PH=14) solution. Figure 4 is the electrochemical performance diagram (LSV) of the oxygen evolution reaction. Figure 4 As shown, at 10 mA cm -2 Under the current density, the overpotential required for the Ni-NiO / Fe(OH)3 / CC catalytic material prepared in Example 1 is only 220 mV, the overpotential required for the Ni / NiO / CC material obtained in Comparative Example 1 is 257 mV, and the overpotential required for the Fe(OH)3 / CC material obtained in Comparative Example 2 is 388 mV.

[0051] In 1 M KOH (PH = 14) solution, 10 mA cm -2 The oxygen evolution reaction stability test was carried out under the current density. Figure 5 is the oxygen evolution reaction stability test diagram of Ni-NiO / Fe(OH)3 / CC catalyst (it); Figure 5As shown in the figure, the Ni-NiO / Fe(OH)3 / CC catalyst can maintain good oxygen evolution reaction stability within 40 h.

[0052] The material was subjected to a hydrogen evolution reaction test in a 1 M KOH (PH=14) solution. Figure 6 is the electrochemical performance diagram (LSV) of the hydrogen evolution reaction. Figure 6 As shown, at 10 mA cm -2 Under the current density, the overpotential required for the Ni-NiO / Fe(OH)3 / CC catalytic material prepared in Example 1 is only 66 mV, the overpotential required for the Ni / NiO / CC catalyst obtained in Comparative Example 1 is 126 mV, and the overpotential required for the Fe(OH)3 / CC catalyst obtained in Comparative Example 2 is 464 mV.

[0053] In 1 M KOH (PH = 14) solution and 10 mA cm -2 The stability test of hydrogen evolution reaction was carried out under the current density. Figure 7 This is the stability test diagram of hydrogen evolution reaction (it). Figure 7 As shown, the Ni-NiO / Fe(OH)3 / CC catalyst prepared in Example 1 maintained good hydrogen evolution reaction stability within 40 hours. This shows that the Ni-NiO / Fe(OH)3 / CC catalyst provided by the present invention can be used as a working electrode (anode) to participate in the oxygen evolution reaction (OER) and as a working electrode (cathode) to participate in the hydrogen evolution reaction (HER), and is an ideal bifunctional catalyst material.

[0054] Application Example 2

[0055] In this application example, a conventional two-electrode system was used to determine the overall water splitting performance of the electrocatalyst described above. A water electrolysis device was assembled using a 1M KOH (pH = 14) solution as the electrolyte, and the Ni-NiO / Fe(OH)3 / CC catalytic material prepared in Example 1 as the anode and cathode, respectively. Linear voltammetry (LSV) was used to determine the electrochemical performance of the material, and chronoamperometry was used to test its stability.

[0056] The Ni-NiO / Fe(OH)3 / CC material prepared in Example 1 was subjected to a full hydrolysis reaction test in a 1M KOH (PH=14) solution. Figure 8 is the electrochemical performance diagram (LSV) of the complete hydrolysis reaction. Figure 8 As shown, at 10 and 100mAcm -2 At the current density, Ni-NiO / Fe(OH)3 / CC only requires low voltages of 1.52 and 1.72 V.

[0057] In 1 M KOH (PH = 14) solution and 10 mA cm -2The stability test of the full hydrolysis reaction was carried out under the current density. Figure 9 This is the stability test diagram of the complete hydrolysis reaction (it). Figure 9 As shown, the chronoamperometry of the Ni-NiO / Fe(OH)3 / CC material prepared in Example 1 shows that it maintains good stability of the full hydrolysis reaction within 40 hours and has a good electrocatalytic effect.

[0058] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a Ni-NiO / Fe(OH)3 / CC bifunctional catalyst, characterized in that: The specific steps include: (1) Soaking the carbon cloth in a nitric acid solution to remove impurities, then placing the carbon cloth in acetone, ethanol, and deionized water for ultrasonic cleaning, and drying the carbon cloth after cleaning to obtain the pretreated carbon cloth; (2) using the carbon cloth pretreated in step (1) as a working electrode, a carbon rod electrode as a counter electrode, and a Hg / HgO electrode as a reference electrode; connecting the circuit, placing the electrode in an electrolytic cell and performing electrochemical deposition; after the electrodeposition is completed, repeatedly rinsing with deionized water, and drying to obtain a Ni / NiO / CC electrode; (3) Immersing the Ni / NiO / CC electrode prepared in step (2) in a Fe(NO3)3 solution, adding a KOH solution dropwise, allowing the reaction to proceed, and then vacuum drying to obtain a Ni-NiO / Fe(OH)3 / CC catalyst; the concentration of the Fe(NO3)3 solution is 0.25 to 1.25 mmoL / L, the concentration of the KOH solution is 1 mmoL / L, and the volume ratio of the Fe(NO3)3 solution to the KOH solution is 3 to 5:

1.

2. The preparation method according to claim 1, characterized in that The drying temperature in step (1) is 60-80°C.

3. The preparation method according to claim 1, characterized in that The electrolyte in the electrolytic cell in step (2) is 20mmoL / L Ni(CH3COOH)2.

4. The preparation method according to claim 1, characterized in that The conditions of the electrochemical deposition in step (2) are: deposition potential of -3V to -1.5V, deposition time of 15 to 30min; the electrochemical deposition is performed once or multiple times.

5. The preparation method according to claim 1, characterized in that The standing reaction time in step (3) is 2 to 6 hours, and the vacuum drying temperature is 50 to 70°C.

6. The Ni-NiO / Fe(OH)3 / CC catalyst prepared according to the preparation method according to any one of claims 1 to 5.

7. Use of the Ni-NiO / Fe(OH)3 / CC catalyst according to claim 6 in the field of perhydrolysis.

8. The use according to claim 7, characterized in that The Ni-NiO / Fe(OH)3 / CC catalyst can carry out oxygen evolution reaction and / or hydrogen evolution reaction.

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