Nickel hydroxide-coated copper dendrite electrocatalyst and preparation method thereof

Abstract

The application discloses a kind of nickel hydroxide coated copper dendrite electrocatalyst, which is prepared by the following method: a piece of foamed copper is soaked in hydrochloric acid solution, the surface oxide layer is removed, and then washed with water and ethanol and dried; the foamed copper substrate is placed in copper sulfate solution, with saturated calomel electrode as reference electrode, carbon rod as counter electrode, and foamed copper as working electrode; electrodeposition is carried out at-1.2 to-1.0V, and then washed with water to obtain copper dendrite loaded foamed copper; the copper dendrite is placed in nickel nitrate solution, with saturated calomel electrode as reference electrode, carbon rod as counter electrode, and foamed copper as working electrode; electrodeposition is carried out at-1.1 to-0.9V, and then washed with water and dried to obtain nickel hydroxide coated copper dendrite electrocatalyst; and a preparation method of nickel hydroxide coated copper dendrite electrocatalyst is provided. The preparation process of the application is simple, the reaction time is short, and the material prepared at normal temperature and pressure has excellent hydrogen production performance for formaldehyde oxidation.

Description

Technical Field

[0001] The invention relates to a nickel hydroxide-coated copper dendrite electrocatalyst and a preparation method thereof. The catalyst can be used for research on formaldehyde oxidation hydrogen production reaction. Background Art

[0002] As an important chemical industrial raw material and zero-carbon energy carrier, hydrogen has a wide range of applications in the industrial and energy fields. Among the many hydrogen production methods, water electrolysis is considered to be one of the most effective methods for large-scale hydrogen production. Traditional water electrolysis consists of a hydrogen evolution reaction at the cathode and an oxygen evolution reaction at the anode. However, the four-electron transfer process and high theoretical potential (1.23V) involved in the oxygen evolution reaction result in the water electrolysis rate being generally limited by the oxygen evolution reaction rate. In addition, the oxygen product of oxygen evolution is cheap and easily causes explosions when mixed with hydrogen, which seriously limits the commercial application of water electrolysis to produce hydrogen.

[0003] Compared to oxygen evolution, small-molecule organic oxidation reactions offer thermodynamic advantages, not only preventing the mixing of H₂ and O₂ but also increasing the value of organic matter. Replacing oxygen evolution with small-molecule organic oxidation can significantly improve the efficiency of hydrogen production from water electrolysis, but this still presents challenges such as high cell pressure and high power consumption for hydrogen production.

[0004] The formaldehyde oxidation reaction can proceed at ultra-low potentials (<0.1V), while simultaneously producing value-added products, formic acid and hydrogen, at the anode. This makes it a promising alternative to the oxygen evolution reaction (OER). Copper-based catalysts can achieve this at ultra-low potentials and are inexpensive compared to precious metal catalysts, making them considered the optimal materials for anodic formaldehyde oxidation. To further improve the performance of copper-based catalysts in formaldehyde oxidation, adjusting the catalyst structure and composition is an effective strategy. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention relates to a nickel hydroxide-coated copper dendrite electrocatalyst for catalyzing formaldehyde oxidation to produce hydrogen and a preparation method thereof, as well as research on its electrocatalytic hydrogen evolution performance. The preparation process is simple and the reaction time is short. The material prepared at room temperature and pressure has excellent formaldehyde oxidation and hydrogen production performance.

[0006] The technical solution adopted in the present invention is:

[0007] A nickel hydroxide-coated copper dendrite electrocatalyst is prepared by the following method:

[0008] (1) Take a piece of 1-4cm 2 The foamed copper was immersed in 1-6M hydrochloric acid solution for 5-30 minutes to remove the surface oxide layer, washed with water and ethanol and then dried;

[0009] (2) placing the copper foam substrate in a 0.1-0.3 M copper sulfate solution, using a saturated calomel electrode as a reference electrode, a carbon rod as a counter electrode, and the copper foam as a working electrode, and electrodepositing at -1.2 to -1.0 V for 100 to 300 seconds, followed by washing with water to obtain copper dendrite-loaded copper foam;

[0010] (3) The copper dendrites were placed in a 0.1-0.2 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. The electrodeposition was performed at -1.1 to -0.9 V for 50 to 150 seconds, and the solution was washed with water and dried to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

[0011] In the present invention, a typical nickel hydroxide-coated copper dendrite electrocatalyst is prepared by a two-step electrodeposition method. The first step is to electrodeposit copper dendrites in an acidic copper sulfate solution, and the second step is to electrodeposit nickel hydroxide in a nickel sulfate solution to form the nickel hydroxide-coated copper dendrite electrocatalyst.

[0012] A method for preparing a nickel hydroxide-coated copper dendrite electrocatalyst, the method comprising the following steps:

[0013] (1) Take a piece of 1-4cm 2 The foamed copper was immersed in 1-6M hydrochloric acid solution for 5-30 minutes to remove the surface oxide layer, washed with water and ethanol and then dried;

[0014] (2) placing the copper foam substrate in a 0.1-0.3 M copper sulfate solution, using a saturated calomel electrode as a reference electrode, a carbon rod as a counter electrode, and the copper foam as a working electrode, and electrodepositing at -1.2 to -1.0 V for 100 to 300 seconds, followed by washing with water to obtain copper dendrite-loaded copper foam;

[0015] (3) The copper dendrites were placed in a 0.1-0.2 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. The electrodeposition was performed at -1.1 to -0.9 V for 50 to 150 seconds, and the solution was washed with water and dried to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

[0016] Furthermore, the concentration of copper sulfate and nickel nitrate, as well as the potential and time of electrodeposition, are regulated to control the morphology and structure of the material.

[0017] Preferably, the thickness of the nickel hydroxide is 5 to 7 nm.

[0018] The formaldehyde oxidation performance test is carried out at room temperature and pressure. The specific operation process is as follows:

[0019] 1) The cutting area is 1×1~2×2cm 2The nickel hydroxide-coated copper dendrite was used as the working electrode, the Hg / HgO electrode was used as the reference electrode, and the graphite rod was used as the counter electrode.

[0020] 2) Formaldehyde oxidation and hydrogen production performance was tested in an H-type electrolytic cell. A working electrode and a reference electrode formed the anode on one side of the cell, and a counter electrode formed the cathode on the other side. The anolyte was a 0.1-1 M KOH solution containing 0.1-0.5 M formaldehyde, and the catholyte was a 0.1-1 M KOH solution. Linear sweep cyclic voltammetry and chronoamperometry testing procedures were used, and a computer was used to monitor the current flowing through the working electrode at different potentials. The formaldehyde concentration in the electrolyte after the electrolysis reaction was calculated using a UV-visible spectrophotometer and a formaldehyde standard curve. The amount of hydrogen produced was calculated using the water displacement method. The catalyst conversion rate and Faradaic efficiency were then calculated.

[0021] The beneficial effects of the present invention are mainly reflected in:

[0022] (1) A nickel hydroxide-coated copper dendrite electrocatalyst was successfully prepared by a two-step electrodeposition method, and its application in formaldehyde oxidation to produce hydrogen was demonstrated.

[0023] (2) Nickel hydroxide-coated copper dendrite electrocatalyst exhibits excellent electrocatalytic performance and stability in the formaldehyde oxidation hydrogen production reaction and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are the SEM and TEM images of the copper dendrite electrocatalyst coated with nickel hydroxide according to the specific embodiment 1 of the present invention.

[0025] Figure 2 This is a contact angle diagram of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 1 of the present invention.

[0026] Figure 3 This is a Raman image of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 1 of the present invention.

[0027] Figure 4 This is the XRD pattern of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 1 of the present invention.

[0028] Figure 5 This is the XPS graph of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 1 of the present invention.

[0029] Figure 6 This is the linear sweep voltammetry curve of the copper dendrite electrocatalyst coated with nickel hydroxide according to the specific embodiment 1 of the present invention.

[0030] Figure 7This is a performance diagram of formaldehyde oxidation and hydrogen production of nickel hydroxide-coated copper dendrite electrocatalyst in specific embodiment 1 of the present invention.

[0031] Figure 8 This is a stability performance diagram of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 1 of the present invention.

[0032] Figure 9 This is the double-layer capacitance curve of the copper dendrite electrocatalyst coated with nickel hydroxide according to the specific embodiment 1 of the present invention.

[0033] Figure 10 This is an SEM image of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 2 of the present invention.

[0034] Figure 11 This is the linear sweep voltammetry curve of the nickel hydroxide-coated copper dendrite electrocatalyst according to specific example 2 of the present invention.

[0035] Figure 12 This is an SEM image of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific embodiment 3 of the present invention.

[0036] Figure 13 This is the linear sweep voltammetry curve of the nickel hydroxide-coated copper dendrite electrocatalyst according to specific example 3 of the present invention.

[0037] Figure 14 This is an SEM image of the copper dendrite electrocatalyst coated with nickel hydroxide according to specific example 4 of the present invention.

[0038] Figure 15 This is the linear sweep voltammetry curve of the nickel hydroxide-coated copper dendrite electrocatalyst of specific example 4 of the present invention. DETAILED DESCRIPTION

[0039] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:

[0040] Reference Figures 1 to 8 , a nickel hydroxide-coated copper dendrite electrocatalyst prepared by the following method:

[0041] (1) Take a piece of 1-4cm 2 The foamed copper was immersed in 1-6M hydrochloric acid solution for 5-30 minutes to remove the surface oxide layer, washed with water and ethanol and then dried;

[0042] (2) placing the copper foam substrate in a 0.1-0.3 M copper sulfate solution, using a saturated calomel electrode as a reference electrode, a carbon rod as a counter electrode, and the copper foam as a working electrode, and electrodepositing at -1.2 to -1.0 V for 100 to 300 seconds, followed by washing with water to obtain copper dendrite-loaded copper foam;

[0043] (3) The copper dendrites were placed in a 0.1-0.2 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. The electrodeposition was performed at -1.1 to -0.9 V for 50 to 150 seconds, and the solution was washed with water and dried to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

[0044] The hydrogen evolution performance test of the nickel hydroxide-coated copper dendrite electrocatalyst of this embodiment was carried out on a CHI 660E electrochemical workstation, and the operation process was as follows:

[0045] 1) The cutting area is 1×1~2×2cm 2 The nickel hydroxide-coated copper dendrite was used as the working electrode, the Hg / HgO electrode was used as the reference electrode, and the graphite rod was used as the counter electrode.

[0046] 2) Formaldehyde oxidation and hydrogen production performance was tested in an H-type electrolytic cell. A working electrode and a reference electrode formed the anode on one side of the cell, and a counter electrode formed the cathode on the other side. The anolyte was a 0.1-1 M KOH solution containing 0.1-0.5 M formaldehyde, and the catholyte was a 0.1-1 M KOH solution. Linear sweep cyclic voltammetry and chronoamperometry testing procedures were selected, and the current flow through the working electrode at different potentials was monitored by a computer. The formaldehyde concentration in the electrolyte after the electrolysis reaction was calculated using a UV-visible spectrophotometer and a formaldehyde standard curve. The amount of hydrogen produced was calculated using the water displacement method. The catalyst conversion rate and Faradaic efficiency were then calculated.

[0047] Example 1

[0048] A method for preparing a nickel hydroxide-coated copper dendrite electrocatalyst, the method comprising the following steps:

[0049] (1) Place a 1.5cm 2 The foamed copper was immersed in 4M hydrochloric acid solution for 20 min to remove the surface oxide layer, washed with water and ethanol and then dried;

[0050] (2) The copper foam substrate was placed in a 0.2 M copper sulfate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and the copper foam as the working electrode. Electrodeposition was performed at -1.1 V for 150 seconds, and the copper foam loaded with copper dendrites was obtained after washing with water.

[0051] (3) The copper dendrites were placed in a 0.15M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and a copper foam as the working electrode, and electroplated at -1.0V for 100 seconds, washed with water, and dried to obtain a nickel hydroxide-coated copper dendrite electrocatalyst. The SEM and TEM images of the nickel hydroxide-coated copper dendrite electrocatalyst obtained in Example 1 are shown in FIG. Figure 1The contact angle diagram of the nickel hydroxide coated copper dendrite electrocatalyst obtained in Example 1 is shown in FIG. Figure 2 Specific Example 1 Raman map of nickel hydroxide coated copper dendrite electrocatalyst Figure 3 The XRD pattern of the nickel hydroxide coated copper dendrite electrocatalyst obtained in Example 1 is shown in FIG. Figure 4 The XPS diagram of the nickel hydroxide coated copper dendrite electrocatalyst obtained in Example 1 is shown in FIG. Figure 5 Specific Example 1 The linear sweep voltammetry curve of the nickel hydroxide coated copper dendrite electrocatalyst is shown in FIG. Figure 6 Specific Example 1 Performance of Formaldehyde Oxidation and Hydrogen Production by Nickel Hydroxide-Coated Copper Dendrite Electrocatalyst Figure 7 Specific Example 1 Stability performance diagram of nickel hydroxide coated copper dendrite electrocatalyst Figure 8 Specific Example 1 Double layer capacitance curve of nickel hydroxide coated copper dendrite electrocatalyst Figure 9 .

[0052] First, the morphology and structure of the prepared nickel hydroxide-coated copper dendrite electrocatalyst were characterized by scanning and transmission electron microscopy, and it was found that the sample had a dendritic structure. From the transmission image, the dendritic morphology of the sample and the outer layer of nickel hydroxide were more clearly observed. The contact angle diagram proved that the catalyst surface was a hydrophilic surface after nickel hydroxide coverage. Through the Raman spectrum, nickel hydroxide and Cu-O bonds were observed, indicating the presence of nickel hydroxide. Through the XRD spectrum, only the peak of elemental copper was observed, and no obvious nickel hydroxide peak was observed, indicating that nickel hydroxide was an amorphous structure. The XPS spectrum further confirmed the presence of nickel hydroxide. Next, the formaldehyde oxidation performance of the nickel hydroxide-coated copper dendrite was explored. In 1M potassium hydroxide and 0.25M formaldehyde electrolyte, a potential of only 0.1V was required to reach 400mA cm -2 The current density was 100%, and the catalyst's Faradaic efficiency for hydrogen production at various potentials remained close to 100%, demonstrating that the nickel hydroxide-coated copper dendrite material is an excellent catalyst for formaldehyde oxidation to produce hydrogen. Cyclic stability testing of the nickel hydroxide-coated copper dendrite revealed little degradation of the catalyst's performance after 16 cycles, demonstrating its excellent stability.

[0053] Example 2:

[0054] A method for preparing a nickel hydroxide-coated copper dendrite electrocatalyst, the method comprising the following steps:

[0055] (1) Place a 1cm 2 The foamed copper was immersed in 1M hydrochloric acid solution for 5 min to remove the surface oxide layer, washed with water and ethanol and then dried;

[0056] (2) The copper foam substrate was placed in a 0.1 M copper sulfate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and the copper foam as the working electrode. Electrodeposition was performed at -1.2 V for 100 seconds, and the copper foam loaded with copper dendrites was obtained after washing with water.

[0057] (3) The copper dendrites were placed in a 0.1 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. Electrodeposition was performed at -1.1 V for 50 seconds, followed by washing with water and drying to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

[0058] First, the morphology and structure of the prepared nickel hydroxide-coated copper dendrites were characterized by scanning, revealing that the sample possesses a dendritic structure. Next, the formaldehyde oxidation performance of the nickel hydroxide-coated copper dendrites was investigated. Tests in a 1M potassium hydroxide and 0.25M formaldehyde electrolyte revealed excellent formaldehyde oxidation performance.

[0059] Example 3:

[0060] A method for preparing a nickel hydroxide-coated copper dendrite electrocatalyst, the method comprising the following steps:

[0061] (1) Place a 4cm 2 The foamed copper was immersed in 6M hydrochloric acid solution for 30 min to remove the surface oxide layer, washed with water and ethanol and then dried;

[0062] (2) The copper foam substrate was placed in a 0.3 M copper sulfate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and the copper foam as the working electrode. Electrodeposition was performed at -1.0 V for 300 seconds, and the copper foam loaded with copper dendrites was obtained after washing with water.

[0063] (3) The copper dendrites were placed in a 0.2 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. Electrodeposition was performed at -0.9 V for 150 seconds, followed by washing with water and drying to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

[0064] First, the morphology and structure of the prepared nickel hydroxide-coated copper dendrites were characterized by scanning, revealing that the sample possesses a dendritic structure. Next, the formaldehyde oxidation performance of the nickel hydroxide-coated copper dendrites was investigated. Tests in a 1M potassium hydroxide and 0.25M formaldehyde electrolyte revealed excellent formaldehyde oxidation performance.

[0065] Example 4:

[0066] A method for preparing a nickel hydroxide-coated copper dendrite electrocatalyst, the method comprising the following steps:

[0067] (1) Place a 2cm 2The foamed copper was immersed in 4M hydrochloric acid solution for 20 min to remove the surface oxide layer, washed with water and ethanol and then dried;

[0068] (2) The copper foam substrate was placed in a 0.2 M copper sulfate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and the copper foam as the working electrode. Electrodeposition was performed at -1.1 V for 200 seconds, and the copper foam loaded with copper dendrites was obtained after washing with water.

[0069] (2) The copper dendrites were placed in a 0.15 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. Electrodeposition was performed at -1.0 V for 100 seconds, followed by washing with water and drying to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

[0070] First, the morphology and structure of the prepared nickel hydroxide-coated copper dendrites were characterized by scanning, revealing that the sample possesses a dendritic structure. Next, the formaldehyde oxidation performance of the nickel hydroxide-coated copper dendrites was investigated. Tests in a 1M potassium hydroxide and 0.25M formaldehyde electrolyte revealed excellent formaldehyde oxidation performance.

Claims

1. Application of a nickel hydroxide-coated copper dendrite electrocatalyst in formaldehyde oxidation to produce hydrogen, characterized in that: The nickel hydroxide-coated copper dendrite electrocatalyst is prepared by the following method: A piece of 1~4 cm 2 The foamed copper was immersed in 1-6 M hydrochloric acid solution for 5-30 min to remove the surface oxide layer, washed with water and ethanol, and then dried; The copper foam substrate was placed in a 0.1-0.3 M copper sulfate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and the copper foam as the working electrode. Electrodeposition was performed at -1.2 to -1.0 V for 100-300 seconds, and copper foam loaded with copper dendrites was obtained after washing with water. The copper dendrites were placed in a 0.1~0.2 M nickel nitrate solution, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and copper foam as the working electrode. Electrodeposition was performed at -1.1~-0.9 V for 50~150 seconds, followed by washing with water and drying to obtain a nickel hydroxide-coated copper dendrite electrocatalyst.

2. The use of the nickel hydroxide-coated copper dendrite electrocatalyst in formaldehyde oxidation to produce hydrogen according to claim 1, characterized in that: The morphology and structure of the material can be controlled by regulating the concentration of copper sulfate and nickel nitrate, the potential and time of electrodeposition.

3. The use of the nickel hydroxide-coated copper dendrite electrocatalyst according to claim 1 or 2 in formaldehyde oxidation to produce hydrogen, characterized in that: The thickness of the nickel hydroxide is 5-7 nm.

Images