NiCo double-metal hydroxide self-supporting nano-catalyst as well as preparation method and application thereof

Abstract

The invention provides a NiCo double hydroxide self-supporting nano-catalyst as well as a preparation method and application thereof, and belongs to the field of nano composite materials. The preparation method of the NiCo double hydroxide self-supporting nano-catalyst is characterized by comprising the following steps: firstly, adding cobalt salt and nickel salt into a solvent, performing ultrasonic treatment to completely dissolve the two metal salts to obtain a metal salt solution, and then assembling a working electrode, a counter electrode and a reference electrode in the metal salt solution to obtain a three-electrode device, and finally, adjusting corresponding parameters in an electrochemical workstation, and carrying out a self-supporting deposition experiment of Ni and Co double-metal hydroxides on the three-electrode device in the electrochemical workstation to obtain the NiCo double-metal hydroxide self-supporting nano-catalyst material with a typical scaly structure and excellent performance. According to the preparation method of the NiCo double-metal hydroxide self-supporting nano-catalyst material, product treatment is convenient and fast, and the process is simple.

Description

Technical Field

[0001] The invention belongs to the field of nano composite materials, and in particular relates to a NiCo double hydroxide self-supporting nano catalyst, a preparation method and application thereof. Background Art

[0002] For nearly a hundred years, the synthesis of NH3 has relied on the HB reaction. Although it can serve as a good energy carrier and energy storage intermediate, this process also emits nearly 1.5% of greenhouse gases. Therefore, it is imperative to develop a sustainable and green ammonia synthesis pathway.

[0003] With the development of industry and agriculture, excessive fertilization, improper discharge of industrial wastewater and domestic sewage have caused nitrate NO3 - Pollution gradually threatens the natural environment and human health. Nitrates have the advantages of low bond energy, high water solubility and high activity, so NO3 - It can be used as a nitrogen source for the synthesis of ammonia under normal temperature and pressure. This synthesis route can not only solve the current dilemma of water pollution but also share the burden of energy shortage. However, NO3 - The conversion to NH3 is a complex process of 8 electrons and 9 protons, and various by-products such as N2 and NO2 may be produced in the process. - , NO and N2H4.

[0004] Transition metal layered double hydroxides (TM-LDHs) have been gradually used as NO3RR electrocatalysts due to their advantages such as easy preparation and low cost. However, TM-LDHs have problems such as easy stacking and easy masking of active sites, which greatly limits the intrinsic catalytic activity of this type of catalyst.

[0005] Therefore, the development of highly selective catalysts for nitrate reduction to produce ammonia has become an urgent issue to be addressed. Summary of the invention

[0006] The present invention is made to solve the above problems, and aims to provide a NiCo double metal hydroxide self-supporting nanocatalyst, a preparation method thereof and application thereof.

[0007] The invention provides a method for preparing a NiCo double metal hydroxide self-supporting nano catalyst material, which has the following characteristics and comprises the following steps: step S1, adding two metal salts, a cobalt salt and a nickel salt, into a solvent, and completely dissolving the two metal salts by ultrasound to obtain a metal salt solution, and transferring the metal salt solution into an electrolytic cell; step S2, assembling a working electrode, a counter electrode and a reference electrode in the metal salt solution to obtain a three-electrode device; step S3, adjusting corresponding parameters in an electrochemical workstation, and performing a self-supporting deposition experiment of Ni and Co double metal hydroxides on the three-electrode device in the electrochemical workstation to obtain the NiCo double metal hydroxide self-supporting nano catalyst material.

[0008] The method for preparing the NiCo double metal hydroxide self-supporting nano catalyst material provided by the present invention may also have the following characteristics: in step S1, the cobalt salt is any one or more of cobalt oxalate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, cobalt chloride hexahydrate, cobalt acetate tetrahydrate, and cobalt acetylacetonate; the nickel salt is any one or more of nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate hexahydrate, nickel nitrate hexahydrate, nickel oxalate, and nickel acetylacetonate; the solvent is any one or more of deionized water, methanol, ethanol, ether, N,N-dimethylacetamide, and N,N-dimethylformamide; the molar ratio of the cobalt salt to the nickel salt is 1.0 to 10.0, and the amount of the solvent used is 30 to 50 mL.

[0009] The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material provided by the present invention may also have the following characteristics, wherein, in step S2, the working electrode includes an electrode clamp and a carbon cloth, the electrode clamp is a platinum sheet electrode clamp, a titanium sheet electrode clamp or a graphite electrode clamp, the counter electrode is a platinum counter electrode, a carbon counter electrode, a glassy carbon electrode or a graphite electrode, and the reference electrode is a calomel electrode, a Hg / HgO electrode, an Ag / AgCl electrode or a Hg / Hg2SO4 electrode.

[0010] The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material provided by the present invention may also have the following characteristics: in step S3, the chemical workstation is Princeton VersaSTAT 4, CHI660E or CHI760E, the voltage range of the self-supporting deposition is -2.0V to 2.0V, and the time of the self-supporting deposition is 5min to 40min.

[0011] The method for preparing the NiCo double metal hydroxide self-supporting nano catalyst material provided by the present invention may also have the following characteristics: the carbon cloth is used after being soaked in an acidic solution, and the acidic solution is a hydrochloric acid, sulfuric acid or nitric acid solution with a concentration of 0.1M to 2M.

[0012] The method for preparing the NiCo double metal hydroxide self-supporting nano catalyst material provided by the present invention may also have the following characteristics: when the carbon cloth is soaked in an acidic solution, the temperature of the acidic solution is 20°C to 100°C, the soaking time is 10min to 180min, and the area of ​​the carbon cloth is 0.25cm 2 ~9cm 2 .

[0013] The present invention provides a NiCo double metal hydroxide self-supporting nano catalyst material having the following characteristics, and is prepared by the preparation method of the NiCo double metal hydroxide self-supporting nano catalyst material provided by the present invention.

[0014] The present invention provides the use of any one of the above described NiCo double metal hydroxide self-supporting nanocatalyst materials as an electrocatalyst.

[0015] Functions and Effects of the Invention

[0016] According to the present invention, a NiCo double metal hydroxide self-supporting nanocatalyst, a preparation method and application thereof, because it includes step one, adding two metal salts of cobalt salt and nickel salt to a solvent, ultrasonically dissolving the two metal salts completely to obtain a metal salt solution; step two, assembling a working electrode, a counter electrode and a reference electrode in the metal salt solution to obtain a three-electrode device; and step three, adjusting the corresponding parameters of the three-electrode device in an electrochemical workstation to perform self-supporting deposition of Ni and Co double metal hydroxides to obtain a NiCo double metal hydroxide self-supporting nanocatalyst material. In the preparation method of the present invention, the strategy of preparing double metal hydroxides by electrodeposition is more convenient and faster than the traditional hydrothermal method and coprecipitation method, the process is simple, and the product treatment is convenient and fast, and it is suitable for preparing non-precious metal (Ni, Co, etc.) catalysts with both high activity and high stability.

[0017] In addition, the present invention uses non-precious metal salts as synthetic raw materials, the raw material reserves are abundant, the industrial cost is low, and it is suitable for medium-scale industrial production.

[0018] In addition, the NiCo double metal hydroxide self-supporting nanocatalyst material prepared by the present invention has a typical flaky structure, can be used as a high-performance catalytic material, has excellent performance and good stability, and has a relatively broad development prospect and application space in the catalytic conversion in the fields of energy and environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a scanning electron microscope image of the NiCo double metal hydroxide self-supporting nanocatalyst material in Example 1 of the present invention;

[0020] Figure 2 is a transmission electron microscope image of the NiCo double metal hydroxide self-supporting nanocatalyst material in Example 1 of the present invention;

[0021] Figure 3 is an X-ray diffraction pattern of the NiCo double metal hydroxide self-supporting nanocatalyst material in Example 1 of the present invention;

[0022] Figure 4 It is a performance test data diagram of the NiCo double metal hydroxide self-supporting nanocatalyst material in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following examples and drawings specifically describe a NiCo double metal hydroxide self-supporting nanocatalyst, its preparation method and application of the present invention.

[0024] <Example 1>

[0025] The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material of this embodiment comprises the following steps:

[0026] Step 1, add any one or more of cobalt oxalate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, cobalt chloride hexahydrate, cobalt acetate tetrahydrate, and cobalt acetylacetonate and any one or more of nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate hexahydrate, nickel nitrate hexahydrate, nickel oxalate, and nickel acetylacetonate to 30-50 mL of deionized water, methanol, ethanol, ether, N,N-dimethylacetamide, and any one or more of N,N-dimethylformamide, and completely dissolve the two metal salts by ultrasound to obtain a metal salt solution, wherein the molar ratio of the cobalt salt to the nickel salt is 1.0-10.0. In this embodiment, the specific experimental process is as follows:

[0027] 1.40 g of cobalt nitrate hexahydrate and 0.35 g of nickel nitrate hexahydrate were added to 30 mL of deionized water, and completely dissolved by ultrasonication to obtain a metal salt solution, which was transferred to an electrolytic cell.

[0028] Step 2: Assemble the working electrode (carbon cloth and platinum electrode clip, titanium electrode clip or graphite electrode clip), platinum counter electrode, carbon counter electrode, glassy carbon electrode or graphite electrode and calomel electrode, Hg / HgO electrode, Ag / AgCl electrode or Hg / Hg2SO4 electrode in a metal salt solution to obtain a three-electrode device, wherein the area of ​​the working electrode is 0.25 cm 2 ~9cm 2 The carbon cloth is immersed in a hydrochloric acid, sulfuric acid or nitric acid solution with a temperature of 20°C to 100°C and a concentration of 0.1M to 2M for 10min to 180min. In this embodiment, the specific experimental process is as follows:

[0029] Use a platinum electrode clamp to fix a piece of 0.5*0.5cm 2 The carbon cloth was used as the working electrode, the platinum sheet was selected as the counter electrode, and the calomel electrode was used as the reference electrode to assemble a three-electrode device. The carbon cloth was heated to 60°C in a dilute hydrochloric acid solution and kept for 120 minutes before use.

[0030] Step 3: In the electrochemical workstation Princeton VersaSTAT 4, CHI660E or CHI760E, the deposition voltage range is adjusted to -2.0V to 2.0V, and the deposition time is 5min to 40min. The three-electrode device is used in the electrochemical workstation to perform a self-supporting deposition experiment of Ni and Co double metal hydroxides to obtain a NiCo double metal hydroxide self-supporting nanocatalyst material. In this embodiment, the specific experimental process is as follows:

[0031] The deposition voltage in the chemical workstation CHI660E was set to -1.1 V, and the deposition time was set to 1200 s. The three-electrode device assembled in step 2 was used in the chemical workstation CHI660E to perform a self-supporting deposition experiment of Ni and Co double metal hydroxides to obtain NiCo double metal hydroxide self-supporting nanocatalyst materials.

[0032] Figure 1 is a scanning electron microscope image of the NiCo double metal hydroxide self-supporting nanocatalyst material in Example 1 of the present invention;

[0033] like Figure 1 As shown, the NiCo double metal hydroxide self-supporting nanocatalyst material prepared in this embodiment has a typical flaky structure. Figure 1 (a) is a scanning electron microscope image at 25K magnification, (b) is a scanning electron microscope image at 50K magnification, and (c) is a scanning electron microscope image at 60K magnification.

[0034] Figure 2 is a transmission electron microscope image of the NiCo double metal hydroxide self-supporting nanocatalyst material in Example 1 of the present invention, Figure 2 (a) is a low-magnification transmission electron microscopy image, (b) is a high-magnification transmission electron microscopy image, (c) is a high-resolution transmission electron microscopy image, and (d) is a selected area electron diffraction image.

[0035] like Figure 2 As shown, the NiCo double metal hydroxide self-supporting nanocatalyst material prepared in this embodiment has a low crystallinity and the lattice is not easy to identify. The fast Fourier transform algorithm (FFT) is applied to find the crystal plane with a crystal plane index of (100), that is, Figure (d). Figure (c) is combined with the high-resolution transmission electron microscopy image to calculate the corresponding crystal plane spacing of 0.279nm.

[0036] Figure 3 : is the X-ray diffraction pattern of the NiCo double hydroxide self-supporting nanocatalyst material in Example 1 of the present invention.

[0037] like Figure 3 As shown, the NiCo double hydroxide self-supporting nanocatalyst material prepared in this embodiment has a Co(OH)2 phase structure.

[0038] Figure 4 It is a performance test data diagram of the NiCo double hydroxide self-supporting nanocatalyst material in Example 1 of the present invention.

[0039] like Figure 4 As shown, Figure 4 (ac) are the performance test data of catalysts with different compositions in 1M NaOH+1M NaNO3 electrolyte, (d) is the performance data of nitrate reduction to produce ammonia rate, and (e) is the Faraday efficiency and stability performance test data of nitrate reduction to produce ammonia.

[0040] like Figure 4 As shown, the NiCo double hydroxide self-supporting nanocatalyst material prepared in this embodiment has excellent nitrate reduction to ammonia rate, high Faradaic efficiency and good cycle stability.

[0041] like Figure 1-4 As shown, the preparation method of the NiCo double metal hydroxide self-supporting nanocatalyst material provided by the present invention can successfully prepare a typical flaky NiCo double metal hydroxide self-supporting nanocatalyst material. The composite material has excellent catalytic activity and stability and can be used as an efficient electrocatalyst for nitrate reduction to produce ammonia.

[0042] <Example 2>

[0043] In this embodiment, based on the preparation conditions of Example 1, the cobalt nitrate hexahydrate in step 1 of Example 1 was replaced with cobalt chloride hexahydrate, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0044] <Example 3>

[0045] In this embodiment, based on the preparation conditions of Example 1, the nickel nitrate hexahydrate in step 1 of Example 1 was replaced with nickel acetylacetonate, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0046] <Example 4>

[0047] In this embodiment, based on the preparation conditions of Example 1, 1.40 g of cobalt nitrate hexahydrate in step 1 of Example 1 was replaced with 0.75 g of cobalt nitrate hexahydrate, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0048] <Example 5>

[0049] In this embodiment, based on the preparation conditions of Example 1, the deionized water in step 1 of Example 1 was replaced with an ethanol solution, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0050] <Example 6>

[0051] In this embodiment, based on the preparation conditions of Example 1, the solvent for treating the carbon cloth in step 2 of Example 1 is replaced by dilute sulfuric acid from dilute hydrochloric acid, and the other steps are the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0052] <Example 7>

[0053] In this embodiment, based on the preparation conditions of Example 1, the working electrode platinum sheet electrode clamp in step 2 of Example 1 is replaced with a graphite electrode clamp, and the other steps are the same as Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0054] <Example 8>

[0055] In this embodiment, based on the preparation conditions of Example 1, the carbon cloth treatment temperature of 60°C in step 2 of Example 1 was changed to 80°C, and the other steps were the same as Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0056] <Example 9>

[0057] In this embodiment, based on the preparation conditions of Example 1, the treatment time of the carbon cloth in step 2 of Example 1 was changed from 120 min to 180 min, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0058] <Example 10>

[0059] In this embodiment, based on the preparation conditions of Example 1, the carbon cloth in step 2 of Example 1 is 0.5*0.5cm 2 Replace with 1.5*1.5cm 2 The other steps are the same as those in Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0060] <Example 11>

[0061] In this embodiment, based on the preparation conditions of Example 1, the reference electrode calomel electrode in step 2 of Example 1 was replaced with a Hg / HgO electrode, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0062] <Example 12>

[0063] In this embodiment, based on the preparation conditions of Example 1, the electrochemical workstation CHI660E in step 3 of Example 1 was replaced with CHI760E, and the other steps were the same as in Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0064] <Example 13>

[0065] In this embodiment, based on the preparation conditions of Example 1, the deposition voltage in step 3 of Example 1 was replaced from -1.1 V to -1.5 V, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0066] <Example 14>

[0067] In this embodiment, based on the preparation conditions of Example 1, the deposition time 1200 s in step 3 of Example 1 was replaced with 1800 s, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0068] <Example 15>

[0069] In this embodiment, based on the preparation conditions of Example 1, the deposition voltage in step 3 of Example 1 was replaced from -1.1 V to 1.1 V, and the other steps were the same as those of Example 1 to prepare a NiCo double metal hydroxide self-supporting nanocatalyst material.

[0070] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a NiCo double metal hydroxide self-supporting nanocatalyst material, characterized in that: The following steps are involved: Step S1, adding two metal salts, cobalt salt and nickel salt, into a solvent, and completely dissolving the two metal salts by ultrasonication to obtain a metal salt solution, which is then transferred into an electrolytic cell; Step S2, assembling a working electrode, a counter electrode and a reference electrode in the metal salt solution to obtain a three-electrode device; Step S3, adjusting the corresponding parameters in the electrochemical workstation, and performing a self-supporting deposition experiment of Ni and Co double metal hydroxides in the three-electrode device in the electrochemical workstation to obtain a NiCo double metal hydroxide self-supporting nanocatalyst material.

2. The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material according to claim 1, characterized in that: in, In step S1, the cobalt salt is any one or more of cobalt oxalate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, cobalt chloride hexahydrate, cobalt acetate tetrahydrate, and cobalt acetylacetonate. The nickel salt is any one or more of nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate hexahydrate, nickel nitrate hexahydrate, nickel oxalate, and nickel acetylacetonate. The solvent is any one or more of deionized water, methanol, ethanol, ether, N,N-dimethylacetamide, and N,N-dimethylformamide. The molar ratio of the cobalt salt to the nickel salt is 1.0 to 10.0, The amount of the solvent used is 30 to 50 mL.

3. The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material according to claim 1, characterized in that: in, In step S2, the working electrode includes an electrode clamp and a carbon cloth, The electrode clamp is a platinum sheet electrode clamp, a titanium sheet electrode clamp or a graphite electrode clamp, The counter electrode is a platinum counter electrode, a carbon counter electrode, a glassy carbon electrode or a graphite electrode, The reference electrode is a calomel electrode, a Hg / HgO electrode, an Ag / AgCl electrode or a Hg / Hg2SO4 electrode.

4. The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material according to claim 1, characterized in that: in, In step S3, the chemical workstation is Princeton VersaSTAT 4, CHI660E or CHI760E, The voltage range of the self-supporting deposition is -2.0V to 2.0V, The self-supporting deposition time is 5 min to 40 min.

5. The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material according to claim 3, characterized in that: in, The carbon cloth is used after being soaked in an acidic solution. The acidic solution is a hydrochloric acid, sulfuric acid or nitric acid solution with a concentration of 0.1M to 2M.

6. The method for preparing the NiCo double metal hydroxide self-supporting nanocatalyst material according to claim 3, characterized in that: in, When the carbon cloth is soaked in an acidic solution, the temperature of the acidic solution is 20°C to 100°C, the soaking time is 10min to 180min, and the area of ​​the carbon cloth is 0.25cm 2 ~9cm 2 .

7. A NiCo double metal hydroxide self-supporting nanocatalyst material, characterized in that: The material is prepared by the method for preparing the NiCo double metal hydroxide self-supporting nano catalyst material according to any one of claims 1 to 6.

8. Use of the NiCo double metal hydroxide self-supporting nanocatalyst material as claimed in claim 7 as an electrocatalyst.

Images