A preparation method of a ruthenium oxide doped molybdenum oxide / nickel hydroxide all-pH electrolytic water catalyst

Abstract

The application discloses a preparation method of a ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst, and belongs to the technical field of catalyst material preparation. The preparation method of the ruthenium oxide doped molybdenum oxide / nickel hydroxide comprises the following steps: firstly, mixing a molybdenum salt with a sodium dodecyl benzene sulfonate aqueous solution, and then placing the mixture into a foamed nickel base; subsequently, performing a hydrothermal reaction, and then performing a calcination treatment in a reducing atmosphere; finally, immersing the calcination product into a RuCl3 solution to obtain a self-supported heterojunction catalyst RuOx-MoO3 / Ni(OH)2. Through the composite structure design of the transition metal molybdenum / nickel base material and the noble metal ruthenium oxide cluster, the technical bottleneck of low activity and poor stability of the traditional ruthenium-based catalyst is effectively solved. The obtained catalyst exhibits excellent hydrogen evolution reaction (HER) activity and long-term stability in a wide pH range.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of catalytic material preparation, in particular to a preparation method of a ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst. BACKGROUND

[0002] To cope with the problems of traditional energy exhaustion and environmental deterioration, developing a clean and renewable energy system has become a global consensus. Hydrogen energy, as a zero-carbon energy carrier, has become the most promising alternative energy due to its high mass energy density (142 MJ / kg) and clean combustion products. Among them, the electrolytic water hydrogen production technology is concerned due to its high product purity and coupling with renewable energy. However, the key bottleneck of this technology is that the actual working voltage is significantly higher than the theoretical decomposition voltage (1.23 V), which leads to low energy conversion efficiency and seriously restricts its large-scale industrial application. Therefore, developing an efficient and stable hydrogen evolution reaction (HER) electrocatalyst has become a core requirement for promoting the commercialization process of the technology.

[0003] Current commercial electrolytic cells generally use platinum-based catalysts, but their industrialization promotion faces three constraints: (1) the crustal abundance of noble metal platinum is extremely low, and the raw material cost is high; (2) Pt is prone to dissolution and deactivation in acidic / alkaline medium, and the long-term stability is insufficient; (3) the pH applicability of the existing catalytic system is limited, and most catalysts only perform excellently under a single pH condition (such as acid or alkali). Therefore, constructing a new catalyst with wide pH adaptability, low noble metal loading and high stability has become a key direction to break through the technical barriers.

[0004] Ruthenium-based catalysts have similar hydrogen adsorption free energy to platinum and exhibit excellent intrinsic activity for HER in a wide pH range. Moreover, its market price is much lower than that of platinum, which has a significant cost advantage. However, ruthenium-based materials still have two defects: (1) they are prone to fall off or form soluble RuO4-2 during electrolysis, leading to activity attenuation; (2) ruthenium nanoparticles are prone to agglomeration, reducing the effective specific surface area. Therefore, in view of the above problems, how to take effective strategies to modify the ruthenium-based materials to reduce the amount of noble metal while improving their activity and stability in the full pH range is a difficult problem existing in the current research. SUMMARY

[0005] In view of the above defects or deficiencies in the prior art, it is expected to provide a preparation method of a ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst.

[0006] The preparation method of the ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst provided by the application comprises the following steps:

[0007] (1) Pretreatment of the base foam nickel to remove surface oil and oxides;

[0008] (2) Dissolve ammonium molybdate tetrahydrate and sodium dodecyl benzene sulfonate in deionized water, and magnetically stir until fully mixed to obtain an initial mixed solution;

[0009] (3) Transfer the pretreated foam nickel and the initial mixed solution into a polytetrafluoroethylene reaction kettle for reaction, and after cooling to room temperature, take out, wash, and vacuum dry to obtain a molybdenum-nickel precursor;

[0010] (4) Place the molybdenum-nickel precursor obtained in step (3) in a porcelain boat and place it in a tube furnace, and perform calcination under a reducing atmosphere, and after cooling to room temperature, take out to obtain a molybdenum-nickel oxide precursor;

[0011] (5) Soak the molybdenum-nickel oxide precursor obtained in step (4) in a ruthenium trichloride solution for reaction, wash the reaction product, and vacuum dry to obtain a self-supporting ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst.

[0012] Preferably, the pretreatment method in step (1) is that the foam nickel with a size of 1 cm*4 cm is sequentially cleaned with acetone and hydrochloric acid for 15 min each, and then washed with deionized water and ethanol repeatedly, and then placed in a vacuum drying box at 60 DEG C for drying for 4-6 h.

[0013] Preferably, in step (2), the molar ratio of ammonium molybdate tetrahydrate to sodium dodecyl benzene sulfonate is (0.8-1.2):1, and dissolved in an appropriate amount of deionized water.

[0014] Preferably, the reaction temperature in step (3) is 120-180 DEG C, and the reaction time is 3-6 h.

[0015] Preferably, the reducing atmosphere in step (4) is 5-20% H2 / Ar, the calcination method is to uniformly increase the temperature from room temperature to 300-500 DEG C at a heating rate of 3-8 DEG C / min, and the temperature is kept for 1-4 h, and then cooled to room temperature and taken out.

[0016] Preferably, the concentration of the ruthenium trichloride solution in step (5) is 0.5-1.5 mg / mL, and the soaking time is 6-12 h.

[0017] In addition, the application aims to provide a use of the ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst in the field of electrolytic water catalysis.

[0018] The evaluation standard of RuOx-MoO3 / Ni(OH)2 electrolytic water hydrogen evolution performance is as follows: electrochemical test is completed on an electrochemical workstation (CHI-760E) using a three-electrode system. In an alkaline condition, the reference electrode is an Hg / HgO electrode, the counter electrode is a carbon rod, the working electrode is RuOx-MoO3 / Ni(OH)2, and the electrolyte is a 1.0 M KOH solution. In a neutral condition, the reference electrode is a saturated calomel electrode, the counter electrode is a carbon rod, the working electrode is RuOx-MoO3 / Ni(OH)2, and the electrolyte is a 1.0 M PBS solution. In an acidic condition, the reference electrode is a saturated calomel electrode, the counter electrode is a carbon rod, the working electrode is RuOx-MoO3 / Ni(OH)2, and the electrolyte is a 0.5 M H2SO4 solution. All test potentials are converted into the potential value of a reversible hydrogen electrode (RHE).

[0019] The beneficial effects of the present application are:

[0020] The present application synthesizes a RuOx-MoO3 / Ni(OH)2 electrolytic water catalyst by a simple hydrothermal method, heat treatment and wet chemical method, which is suitable for HER electrocatalysis in a full pH range. The preparation method is simple, low in cost and more suitable for large-scale industrial production. Compared with the currently reported catalysts which can only be used in acidic or alkaline electrolyte, the overpotential of the catalyst is only 72 mV, 155 mV and 84 mV at a current density of 100 mA cm-2 in alkaline, neutral and acidic electrolyte. The catalyst can be applied to HER in a full pH range, and the activity is better than that of a commercial Pt / C electrocatalyst, which provides an industrial possibility for hydrogen production by electrolytic water

[0021] It should be understood that the content described in the summary section is not intended to limit or define key or important features of embodiments of the application, nor is it used to limit the scope of the application. Other features of the application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0022] Other features, objects, and advantages of the application will become apparent from a reading of the following detailed description together with the drawings, in which:

[0023] Figure 1 A scanning electron microscope image (SEM) of the catalyst prepared for Example 1;

[0024] Figure 2 A transmission electron microscope image (TEM) of the catalyst prepared for Example 1;

[0025] Figure 3 An atomic force microscope image (AFM) of the catalyst prepared for Example 1, and the inset is a corresponding height profile;

[0026] Figure 4 Transmission electron microscope energy dispersive X-ray spectroscopy (EDS) of the catalyst prepared in Example 1 was prepared;

[0027] Figure 5 Polarization curves of the catalyst prepared in Example 1 in 1.0 M KOH, 1.0 M PBS, 0.5 M H2SO4 electrolyte, respectively, were prepared;

[0028] Figure 6 Chronoamperometric curves of the catalyst prepared in Example 1 in 1.0 M KOH, 1.0 M PBS, 0.5 M H2SO4 electrolyte, respectively, were prepared. DETAILED DESCRIPTION

[0029] The application will be further described below in conjunction with the drawings and examples. It can be understood that the specific examples described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0030] It should be noted that the examples in the application and the features in the examples can be combined with each other without conflict. The application will be described in detail below with reference to the drawings and in conjunction with the examples.

[0031] The following examples are given:

[0032] Example 1

[0033] (1) Pretreatment of the foam nickel substrate: 1 cm x 4 cm foam nickel was sequentially cleaned with acetone and 3 M hydrochloric acid for 15 min each, then washed with deionized water and ethanol repeatedly, and then placed in a vacuum drying oven at 60 ℃ for 4 h.

[0034] (2) Dissolve 0.0988 g of ammonium molybdate tetrahydrate and 0.0278 g of sodium dodecylbenzenesulfonate in 30 ml of deionized water, and magnetically stir until fully mixed to obtain an initial mixed solution.

[0035] (3) Transfer the pretreated foam nickel substrate (1 cm x 4 cm) and the initial mixed solution to a polytetrafluoroethylene reaction kettle, and react from room temperature to 160 ℃ for 4 h. After cooling to room temperature, the product was taken out, washed, and vacuum dried to obtain a molybdenum-nickel precursor.

[0036] (4) Put the molybdenum-nickel precursor obtained in step (3) into a tube furnace, and heat it from room temperature to 450 ℃ at a heating rate of 5 ℃ / min under an atmosphere of 10% H2 / Ar, and keep the temperature for 2 h. After cooling to room temperature, a molybdenum-nickel oxide precursor was obtained.

[0037] (5) The molybdenum-nickel oxide precursor obtained in step (4) is immersed in 8 mL of a ruthenium trichloride solution with a concentration of 0.8 mg / ml for reaction for 9 h, and the reaction product is washed and vacuum dried to obtain a self-supported ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH electrolytic water catalyst.

[0038] From Figure 1 and Figure 2 It can be seen that the morphology of the prepared ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH electrolytic water catalyst is nanosheet flower-like morphology. And from Figure 3 It can be seen that the thickness of the nanosheet of the prepared ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH electrolytic water catalyst is about 2 nm.

[0039] Example 2

[0040] (1) The foam nickel substrate is pretreated, and a 1 cm×4 cm foam nickel is ultrasonically cleaned with acetone and 3 M hydrochloric acid for 15 min, respectively, and then repeatedly washed with deionized water and ethanol, and then placed in a vacuum drying box at 60°C for drying for 4 h.

[0041] (2) 0.1235 g of ammonium molybdate tetrahydrate and 0.0278 g of sodium dodecylbenzenesulfonate are dissolved in 30 ml of deionized water, and magnetically stirred until fully mixed to obtain an initial mixed solution.

[0042] (3) The pretreated foam nickel substrate (1 cm×4 cm) and the initial mixed solution are transferred to a polytetrafluoroethylene reaction kettle for reaction, and the temperature is increased from room temperature to 160°C for 4 h. After cooling to room temperature, the product is taken out, washed, and vacuum dried to obtain a molybdenum-nickel precursor.

[0043] (4) The molybdenum-nickel precursor obtained in step (3) is placed in a tube furnace, and the temperature is increased from room temperature to 450°C at a rate of 5°C / min under an atmosphere of 10% H2 / Ar, and held for 2 h. After cooling to room temperature, a molybdenum-nickel oxide precursor is obtained.

[0044] (5) The molybdenum-nickel oxide precursor obtained in step (4) is immersed in 8 mL of a ruthenium trichloride solution with a concentration of 0.8 mg / ml for reaction for 9 h, and the reaction product is washed and vacuum dried to obtain a self-supported ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH electrolytic water catalyst.

[0045] Example 3

[0046] (1) The foam nickel substrate is pretreated, and a 1 cm×4 cm foam nickel is ultrasonically cleaned with acetone and 3 M hydrochloric acid for 15 min, respectively, and then repeatedly washed with deionized water and ethanol, and then placed in a vacuum drying box at 60°C for drying for 4 h.

[0047] (2) Dissolve 0.988 g of ammonium molybdate tetrahydrate and 0.0278 g of sodium dodecyl benzene sulfonate in 30 ml of deionized water, magnetically stir until fully mixed to obtain an initial mixed solution.

[0048] (3) Transfer the pretreated foamed nickel substrate (1 cm x 4 cm) and the initial mixed solution into a polytetrafluoroethylene reaction kettle to react, from room temperature to 140 ℃ for 4 h, and after cooling to room temperature, take out the product, wash, and vacuum dry to obtain a molybdenum-nickel precursor.

[0049] (4) Put the molybdenum-nickel precursor obtained in step (3) into a tube furnace, and under the atmosphere of 10% H2 / Ar, from room temperature to 550 ℃ at a heating rate of 5 ℃ / min, and keep for 2 h, and after cooling to room temperature, obtain a molybdenum-nickel oxide precursor.

[0050] (5) Soak the molybdenum-nickel oxide precursor obtained in step (4) in 8 mL of a ruthenium trichloride solution with a concentration of 0.8 mg / ml for 9 h, wash the reaction product, and vacuum dry to obtain a self-supporting ruthenium oxide doped molybdenum oxide / nickel hydroxide full-pH electrolytic water catalyst.

[0051] Application Example

[0052] The classic three-electrode system is applied, and the electrochemical performance of the material is tested on an electrochemical workstation system. The obtained catalyst is directly used as a working electrode without further treatment. A carbon rod is used as a counter electrode, and a mercury oxide electrode is used as a reference electrode in an alkaline solution (1.0 M KOH). In an acidic (0.5 M H2SO4) and neutral (1.0 M PBS) solution, a saturated calomel electrode is used as a reference electrode. The linear sweep voltammetry (LSV) is adopted at a scanning rate of 10 mV s -1 -1, the IR compensation rate is 90%, and the HER polarization curve is obtained by linear sweep voltammetry (LSV). The stability of the catalyst is determined by chronoamperometry. The test data of examples 1-3 are shown in Table 1. At a current density of 100 mA cm -2 -1, the overvoltage of RuOx-MoO3 / Ni(OH)2 in alkaline, neutral, and acidic solutions is only 72 mV, 155 mV, and 84 mV, indicating that the obtained hydrogen production catalyst for electrolytic water has excellent hydrogen production performance in the full-pH range.

[0053] Table 1 Comparison of hydrogen production catalyst performance for electrolytic water in alkaline, neutral, and acidic electrolytes (current density is 100 mA cm -2 )

[0054]

[0055] In the description of the present specification, the terms "connection", "installation", "fixation" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, or detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0056] In the description of the present specification, the description of the terms "one embodiment", "some embodiments" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0057] The above is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst, characterized in that, Includes the following steps: (1) Dissolve ammonium molybdate tetrahydrate and sodium dodecylbenzenesulfonate in deionized water and stir magnetically until fully mixed to obtain an initial mixed solution; (2) The clean nickel foam substrate and the above initial mixed solution were transferred to a polytetrafluoroethylene reactor for reaction. After cooling to room temperature, the substrate was taken out, washed, and vacuum dried to obtain the molybdenum nickel precursor. (3) The molybdenum-nickel precursor obtained in step (2) is placed in a tube furnace and calcined in a reducing atmosphere. After cooling to room temperature, the molybdenum-nickel oxide precursor is obtained. (4) The molybdenum nickel oxide precursor obtained in step (3) is immersed in ruthenium trichloride solution for reaction. The reaction product is washed and vacuum dried to obtain a self-supporting ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst.

2. The preparation method of the ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst according to claim 1, characterized in that, In step (1), the ratio of the amount of ammonium molybdate tetrahydrate and sodium dodecylbenzenesulfonate added is (0.8~1.2):1, and they are dissolved in an appropriate amount of deionized water.

3. The preparation method of the ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst according to claim 1, characterized in that, The reaction temperature in step (2) is 120~180 ℃ and the reaction time is 3~6 h.

4. The preparation method of the ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst according to claim 1, characterized in that, The reducing atmosphere described in step (3) is 5~20% H2 / Ar. The calcination method is to uniformly raise the temperature from room temperature to 300~500 ℃ at a rate of 3~8℃ / min, hold the temperature for 1~4 h, and then remove the product after cooling to room temperature.

5. The preparation method of a ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst according to claim 1, characterized in that, The concentration of the ruthenium trichloride solution in step (4) is 0.5~1.5 mg / mL, and the soaking time is 6~12 h.

6. The preparation method of the ruthenium oxide-doped molybdenum oxide / nickel hydroxide all-pH water electrolysis catalyst according to claim 1, characterized in that, The invention includes a substrate and a ruthenium oxide-doped molybdenum oxide / nickel hydroxide supported on the substrate, wherein the ruthenium content in the ruthenium oxide-doped molybdenum oxide / nickel hydroxide is 0.5% to 1.8%.

7. A ruthenium oxide-doped molybdenum oxide / nickel hydroxide nanosheet electrocatalytic material prepared by the preparation method according to any one of claims 1 to 6.

8. An application of the ruthenium oxide-doped molybdenum oxide / nickel hydroxide nanosheet electrocatalytic material as described in claim 7, characterized in that, Application as a catalyst in HER (hydrogen production via full pH electrolysis of water).

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