Preparation method of foamed nickel-based water electrolysis oxygen evolution catalyst

Abstract

The present invention provides a method for preparing a nickel foam-based catalyst for oxygen evolution by electrolysis of water, belonging to the technical field of hydrogen production by electrolysis of water. The present invention provides a method for preparing a nickel foam-based catalyst for oxygen evolution by electrolysis of water, comprising the following steps: modifying nickel foam using water plasma to obtain the nickel foam-based catalyst for oxygen evolution by electrolysis of water. The present invention adopts a water plasma treatment method to quickly and conveniently form nickel / iron oxyhydroxides on the surface of the nickel foam, thereby improving the oxygen evolution reaction activity of the nickel foam and obtaining a highly efficient nickel foam-based electrocatalyst. The treatment process is simple, does not require a large amount of solvent, does not generate waste liquid, and has a short treatment time, which is far less than the dozen or so hours required in the prior art. In addition, the hydroxides generated on the surface of the nickel foam can change its wettability to water.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis of water, and in particular to a method for preparing a foamed nickel-based catalyst for oxygen evolution by electrolysis of water. Background Art

[0002] Hydrogen production from water electrolysis is a key technology for achieving green hydrogen energy. The slow kinetics of the cathode hydrogen evolution reaction and the anodic oxygen evolution reaction are key issues limiting their development. Developing efficient electrode catalysts is an important way to promote the large-scale application of hydrogen production from water electrolysis technology. Compared with the cathode hydrogen evolution reaction, the anodic oxygen evolution reaction has a higher overpotential. Improving the electrocatalytic activity of the oxygen evolution reaction is a major challenge. Nickel foam, due to its three-dimensional self-supporting porous structure, has good electrocatalytic activity and is widely used as an electrode material for hydrogen production from alkaline water electrolysis. Nickel foam can also be used as a supporting material, modified on the surface or loaded with other catalysts to prepare nickel foam-based composite materials with higher electrochemical activity.

[0003] Nickel-iron double hydroxide and its derivatives supported on nickel foam (NiFe-LDH / NF) are common composite materials with advantages such as high catalytic activity in the oxygen evolution reaction, ease of preparation, and adjustable structure. Currently, they are mainly prepared through hydrothermal, electrochemical deposition, and impregnation methods. The hydrothermal method involves immersing the nickel foam in a precursor solution for a hydrothermal reaction, causing the catalyst to grow or deposit on the surface of the nickel foam; the electrochemical deposition method involves electrolytically depositing the precursor from the electrolyte onto the nickel foam surface; and the impregnation method involves directly immersing the nickel foam in the precursor solution, where the catalyst is deposited on the nickel foam surface through a chemical reaction. These methods can produce NiFe-LDH / NF catalysts with different compositions and can regulate the structure and morphology of the catalyst.

[0004] However, the existing preparation method of NiFe-LDH / NF has a complex process and a long reaction time, and a large amount of waste liquid is inevitably generated after the reaction is completed, which increases the cost of waste treatment. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for preparing a nickel foam-based water electrolysis oxygen evolution catalyst. The method quickly and conveniently forms nickel or nickel / iron oxyhydroxide on the surface of nickel foam without requiring a large amount of solvent and without generating waste liquid.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a foamed nickel-based water electrolysis oxygen evolution catalyst, comprising the following steps:

[0008] The foamed nickel is modified by water plasma to obtain the foamed nickel-based water electrolysis and oxygen evolution catalyst.

[0009] Preferably, the water plasma is obtained from a radio frequency plasma source.

[0010] Preferably, the power of the radio frequency plasma source is 0-500W, and the power of the radio frequency plasma source is not 0, and the frequency of the radio frequency plasma source is 13.56 MHz.

[0011] Preferably, the preparation parameters of the water plasma include: a chamber pressure of 10 to 50 Pa, a gas atmosphere of a mixture of argon and water vapor, a volume content of water vapor in the mixture of 2% to 100%, and a flow rate of argon of 10 to 30 sccm.

[0012] Preferably, the modification time is 1 to 60 minutes.

[0013] Preferably, the nickel foam further includes a pretreatment before modification, wherein the pretreatment includes sequentially ultrasonic treatment with an acidic solution, water, and anhydrous ethanol, followed by drying.

[0014] Preferably, the acidic solution is a dilute hydrochloric acid solution, and the mass fraction of the dilute hydrochloric acid solution is 1% to 10%.

[0015] Preferably, the nickel foam further comprises iron oxide loading before modification, and the iron oxide loading comprises the following steps:

[0016] The nickel foam is immersed in a soluble iron salt solution and then dried to obtain a nickel foam with iron salt loaded on the surface;

[0017] The nickel foam with the iron salt loaded on the surface is calcined to obtain the nickel foam with the iron oxide loaded on the surface.

[0018] Preferably, the calcination temperature is 200-600° C., and the calcination time is 0.5-2 h.

[0019] Preferably, the soluble iron salt in the soluble iron salt solution includes ferric nitrate or ferric chloride.

[0020] The invention provides a preparation method of a nickel foam-based water electrolysis oxygen evolution catalyst, comprising the following steps: modifying nickel foam by using water plasma to obtain the nickel foam-based water electrolysis oxygen evolution catalyst.

[0021] The present invention uses a water plasma treatment method to quickly and conveniently form nickel or nickel / iron oxyhydroxides on the surface of nickel foam, improving the foam's oxygen evolution reaction activity and producing a highly efficient nickel-based foam electrocatalyst. The treatment process is simple, requires no large amounts of solvents, produces no waste liquid, and takes a short treatment time, far less than the several hours required by existing methods. Furthermore, the hydroxides formed on the surface of the nickel foam alter its wettability to water.

[0022] The present invention utilizes water plasma to treat nickel foam to prepare a Ni(O)OH / NF catalyst, and further, a (Fe / Ni)(O)OH / NF catalyst can also be obtained.

[0023] Furthermore, in the present invention, the RF plasma source power is different, and the species and ionization degree of the generated water plasma are different. By regulating the water plasma treatment parameters and the Fe / Ni ratio of the precursor, the ratio of hydroxide to oxyhydroxide in the (Fe / Ni)(O)OH / NF catalyst can be controlled, thereby further improving the oxygen evolution reaction activity of the foamed nickel-based catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a water plasma device for preparing electrocatalysts;

[0025] Figure 2 The effect of water plasma treatment on the surface morphology of NF, where a is the scanning electron microscope image of NF without water plasma treatment, and b is the scanning electron microscope image of Ni(O)OH / NF;

[0026] Figure 3 The effect of water plasma treatment on the surface morphology of FeNi two-component surface, where a is the scanning electron microscope image of FeOx / NF and b is the scanning electron microscope image of (Fe / Ni)(O)OH / NF;

[0027] Figure 4 is the effect of water plasma treatment on surface hydrophilicity, where a is the contact angle of NF without water plasma treatment, and b is the contact angle of Ni(O)OH / NF catalyst;

[0028] Figure 5 The OER performance of electrocatalysts prepared by water plasma method, where a is the oxygen evolution activity curve of NF and Ni(O)OH / NF catalyst, and b is the FeO x Oxygen evolution activity curves of (Fe / Ni)(O)OH / NF and (Fe / Ni)(O)OH / NF catalysts. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a foamed nickel-based water electrolysis oxygen evolution catalyst, comprising the following steps:

[0030] The foamed nickel is modified by water plasma to obtain the foamed nickel-based water electrolysis and oxygen evolution catalyst.

[0031] In the present invention, the water plasma is obtained from a radio frequency plasma source.

[0032] In the present invention, the radio frequency plasma source is preferably generated by the principle of inductive coupling, with a quartz tube as the sample processing chamber, and a copper coil is wound around the outside of the quartz tube.

[0033] In the present invention, the power of the radio frequency plasma source is preferably 0 to 500 W, more preferably 100 to 300 W, and the power of the radio frequency plasma source is not 0. The frequency of the radio frequency plasma source is preferably 13.56 MHz.

[0034] In the present invention, the preparation parameters of the water plasma include: the chamber pressure is preferably 10 to 50 Pa, more preferably 20 to 30 Pa, the gas atmosphere is preferably a mixture of argon and water vapor, the volume content of water vapor in the mixture is preferably 2% to 100%, and the flow rate of the argon gas is preferably 10 to 30 sccm.

[0035] In a specific embodiment of the present invention, the water plasma is preferably Figure 1 The device shown is produced, a quartz tube is used as a sample processing chamber, a copper coil is wrapped around the outside of the quartz tube, and radio frequency plasma is generated using the principle of inductive coupling. A mechanical pump evacuates the downstream of the quartz tube, and argon is filled into the upstream of the quartz tube. Before the argon is filled into the quartz tube, it passes through a tank filled with pure water. The temperature of the water storage tank is controlled at 20-100°C. The argon is used as a carrier gas to bring water vapor into the quartz tube. The argon flow rate and the temperature of the water storage tank are controlled to keep the pressure in the quartz tube at 10-50 Pa. The radio frequency power supply is used to generate water plasma. The quartz tube is mainly a mixture of argon and water vapor, with a water vapor volume content of 2% to 100%. The water plasma is generated, and the power of the radio frequency power supply is adjusted to change the state of the water plasma.

[0036] In the present invention, the modification time is preferably 1 to 60 minutes, more preferably 10 to 30 minutes.

[0037] In the present invention, the nickel foam preferably further includes pretreatment before modification, and the pretreatment preferably includes sequentially ultrasonic treatment with an acidic solution, water, and anhydrous ethanol, followed by drying.

[0038] In the present invention, the acidic solution is preferably a dilute hydrochloric acid solution, and the mass fraction of the dilute hydrochloric acid solution is preferably 1% to 10%.

[0039] In the present invention, the ultrasonic treatment time is preferably 15 minutes, and the function of the ultrasonic treatment is to remove impurities on the surface of the nickel foam.

[0040] In the present invention, the drying temperature is preferably 60° C., and the drying time is preferably 2 hours.

[0041] In the present invention, the nickel foam preferably further comprises iron oxide loading before modification, and the iron oxide loading preferably comprises the following steps:

[0042] The nickel foam is immersed in a soluble iron salt solution and then dried to obtain a nickel foam with iron salt loaded on the surface;

[0043] The nickel foam with iron salt loaded on the surface is calcined to obtain nickel foam with iron oxide loaded on the surface (FeO x / NF).

[0044] In the present invention, the nickel foam preferably further includes pretreatment before impregnation. The pretreatment method is preferably consistent with the above solution and will not be described in detail here.

[0045] In the present invention, the soluble iron salt in the soluble iron salt solution preferably includes ferric nitrate or ferric chloride.

[0046] In the present invention, the concentration of the soluble iron salt solution is preferably 1 mol / L.

[0047] In the present invention, the immersion time is preferably 20 minutes.

[0048] In the present invention, the drying temperature is preferably 60° C., and the drying time is preferably 8 hours.

[0049] In the present invention, the calcination temperature is preferably 200-600° C., more preferably 400° C., and the calcination time is preferably 0.5-2 h, more preferably 1 h.

[0050] The present invention has no particular limitation on the application of the foamed nickel-based water electrolysis oxygen evolution catalyst, and any method well known to those skilled in the art may be used.

[0051] To further illustrate the present invention, the preparation method of the foamed nickel-based water electrolysis oxygen evolution catalyst provided by the present invention is described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] (1) Pretreatment of nickel foam:

[0054] The nickel foam was sequentially ultrasonically treated with a 1% by mass dilute hydrochloric acid solution, water, and anhydrous ethanol for 15 minutes, and then dried in an oven at 60° C. for 2 hours to obtain a clean nickel foam.

[0055] (2) Water plasma generation (device see Figure 1 ):

[0056] a. A quartz tube is used as the sample processing chamber. A copper coil is wrapped around the outside of the quartz tube, and radio frequency plasma is generated using the principle of inductive coupling.

[0057] b. A mechanical pump evacuates the quartz tube downstream, while argon is introduced upstream at a flow rate of 10 to 30 sccm. Before entering the tube, the argon passes through a tank filled with pure water. The water tank temperature is controlled between 20 and 100°C. The argon acts as a carrier gas, carrying water vapor into the tube. The argon flow rate and water tank temperature are controlled to maintain a pressure within the tube between 10 and 50 Pa.

[0058] c. Use a 13.56MHz RF power supply to generate plasma. The quartz tube contains a mixture of argon and water vapor with a water vapor volume content of 2%. Water plasma is generated. The power of the RF power supply is adjusted to change the state of the water plasma. The power range is 0 to 500W.

[0059] (3) Water plasma treatment samples:

[0060] a. Place the pre-treated nickel foam into the quartz tube at the coil position.

[0061] b. Evacuate the chamber, introduce water vapor, and turn on the RF power supply to generate water plasma. The RF power is 300W, the argon flow rate is 30ccm, the chamber pressure is 50Pa, and the treatment time is 1 minute.

[0062] c. After the clean nickel foam treatment is completed, Ni(O)OH / NF catalyst is obtained.

[0063] The Ni(O)OH / NF catalyst prepared by this method was subjected to morphology analysis, hydrophilicity analysis and oxygen evolution performance test.

[0064] Morphology and structure Figure 2 , Figure 2 Figure 1 shows the effect of water plasma treatment on the surface morphology of nickel foam. (a) shows a smooth surface of a NF without water plasma treatment; (b) shows a large number of nanoparticles on the surface of a Ni(O)OH / NF. Analysis of the SEM images shows that after water plasma treatment, the clean nickel foam retains its three-dimensional skeleton structure, and the smooth surface of the nickel foam is loaded with a large number of nanoparticles.

[0065] Hydrophilicity analysis see Figure 4 , where a is the contact angle of NF without water plasma treatment, which is 118°, showing a certain degree of hydrophobicity; b is the contact angle of Ni(O)OH / NF catalyst, which is 0°, showing a super-hydrophilic structure with significantly improved hydrophilicity.

[0066] Oxygen evolution performance test see Figure 5 , where a is the oxygen evolution activity curve of NF and Ni(O)OH / NF catalyst. It can be seen that the Ni(O)OH / NF catalyst obtained after water plasma treatment has an oxygen evolution activity of 10 mA·cm -2The overpotential at the current density is 400mV, and the overpotential of Ni(O)OH / NF is 92mV lower than that of untreated nickel foam.

[0067] Example 2

[0068] (1) Pretreatment of nickel foam:

[0069] a. The nickel foam was sequentially ultrasonically treated with a 1% mass fraction of dilute hydrochloric acid solution, water, and anhydrous ethanol for 15 minutes, and then dried in an oven at 60°C for 2 hours to obtain a clean nickel foam.

[0070] b. Place the clean nickel foam in 20 mL of 1 M ferric nitrate solution, immerse for 20 minutes, take it out, and dry it in an oven at 60 ° C for 8 hours to obtain a nickel foam with iron salts on the surface. Calcinate it at 400 ° C for 1 hour to obtain a nickel foam with iron oxides on the surface (FeO x / NF).

[0071] (2) Water plasma generation (device see Figure 1 ):

[0072] a. A quartz tube is used as the sample processing chamber. A copper coil is wrapped around the outside of the quartz tube, and radio frequency plasma is generated using the principle of inductive coupling.

[0073] b. A mechanical pump evacuates the quartz tube downstream, while argon is introduced upstream at a flow rate of 10 to 30 sccm. Before entering the tube, the argon passes through a tank filled with pure water. The water tank temperature is controlled between 20 and 100°C. The argon acts as a carrier gas, carrying water vapor into the tube. The argon flow rate and water tank temperature are controlled to maintain a pressure within the tube between 10 and 50 Pa.

[0074] c. Use a 13.56MHz RF power supply to generate plasma. The quartz tube contains a mixture of argon and water vapor with a water vapor volume content of 2%. Water plasma is generated. The power of the RF power supply is adjusted to change the state of the water plasma. The power range is 0 to 500W.

[0075] (3) Water plasma treatment samples:

[0076] a. The nickel foam loaded with iron oxide (FeO x / NF) is placed in the quartz tube at the position of the coil.

[0077] b. Evacuate the chamber, introduce water vapor, and turn on the RF power supply to generate water plasma. The RF power is 300W, the argon flow rate is 30ccm, the chamber pressure is 50Pa, and the treatment time is 1 minute.

[0078] c. After the treatment of nickel foam loaded with iron oxide, the (Fe / Ni)(O)OH / NF catalyst was obtained.

[0079] Figure 3 The effect of water plasma treatment on the surface morphology of FeNi two-component surface, where a is FeO x a is a scanning electron microscope photo of (a) / NF, the surface of which is a structure composed of uneven particles; b is a scanning electron microscope photo of (Fe / Ni)(O)OH / NF, the surface of which is a large number of flaky structures. After the nickel foam loaded with iron oxide is treated with water plasma, the nickel foam still maintains a three-dimensional skeleton structure, and there are a large number of flaky structures on the surface.

[0080] The oxygen evolution performance of the (Fe / Ni)OOH / NF catalyst prepared by this method was tested. Figure 5 b, (Fe / Ni)(O)OH / NF catalyst obtained after water plasma treatment at 10 mA·cm -2 The overpotential at this current density is 246 mV, and the overpotential of the (Fe / Ni)(O)OH / NF catalyst is 97 mV lower than that of the iron oxide-loaded nickel foam before water plasma treatment.

[0081] Example 3

[0082] (1) Pretreatment of nickel foam:

[0083] a. The nickel foam was sequentially ultrasonically treated with a 1% mass fraction of dilute hydrochloric acid solution, water, and anhydrous ethanol for 15 minutes, and then dried in an oven at 60°C for 2 hours to obtain a clean nickel foam.

[0084] b. Place the clean nickel foam in 20 mL of 1 M ferric nitrate solution, immerse for 20 minutes, take it out, and dry it in an oven at 60 ° C for 8 hours to obtain a nickel foam with iron salts on the surface. Calcinate it at 400 ° C for 1 hour to obtain a nickel foam with iron oxides on the surface (FeO x / NF).

[0085] (2) Water plasma generation (device see Figure 1 ):

[0086] a. A quartz tube is used as the sample processing chamber. A copper coil is wrapped around the outside of the quartz tube, and radio frequency plasma is generated using the principle of inductive coupling.

[0087] b. A mechanical pump evacuates the quartz tube downstream, while argon is introduced upstream at a flow rate of 10 to 30 sccm. Before entering the tube, the argon passes through a tank filled with pure water. The water tank temperature is controlled between 20 and 100°C. The argon acts as a carrier gas, carrying water vapor into the tube. The argon flow rate and water tank temperature are controlled to maintain a pressure within the tube between 10 and 50 Pa.

[0088] c. Use a 13.56MHz RF power supply to generate plasma. The quartz tube contains a mixture of argon and water vapor with a water vapor volume content of 10%. Water plasma is generated. The power of the RF power supply is adjusted to change the state of the water plasma. The power range is 0 to 500W.

[0089] (3) Water plasma treatment samples:

[0090] a. The nickel foam loaded with iron oxide (FeO x / NF) is placed in the quartz tube at the position of the coil.

[0091] b. Evacuate the chamber, introduce water vapor, and turn on the RF power supply to generate water plasma. The RF power is 300W, the argon flow rate is 30ccm, the chamber pressure is 50Pa, and the treatment time is 60 minutes.

[0092] c. After the treatment of nickel foam loaded with iron oxide, the (Fe / Ni)(O)OH / NF catalyst was obtained.

[0093] The oxygen evolution performance of the (Fe / Ni)(O)OH / NF catalyst prepared by this method was tested. The (Fe / Ni)(O)OH / NF catalyst prepared by water plasma treatment showed an oxygen evolution performance of 10 mA·cm -2 The overpotential at this current density is 280 mV, and the overpotential of the (Fe / Ni)OOH / NF catalyst is 63 mV lower than that of the iron oxide-loaded nickel foam before water plasma treatment.

[0094] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a foamed nickel-based water electrolysis oxygen evolution catalyst, characterized in that: The following steps are involved: Modifying nickel foam by water plasma to obtain the nickel foam-based water electrolysis and oxygen evolution catalyst; The water plasma is obtained from a radio frequency plasma source; The power of the radio frequency plasma source is 100-300 W, and the frequency of the radio frequency plasma source is 13.56 MHz; The preparation parameters of the water plasma include: a chamber pressure of 10-50 Pa, a gas atmosphere of a mixture of argon and water vapor, a volume content of water vapor in the mixture of 2%-100%, and a flow rate of the argon gas of 10-30 sccm; The modification time is 1 to 60 minutes; A quartz tube is used as a sample processing chamber, a copper coil is wound around the outside of the quartz tube, radio frequency plasma is generated using the principle of inductive coupling, and the foamed nickel is placed in the quartz tube at the location of the coil for the modification.

2. The preparation method according to claim 1, characterized in that The nickel foam further includes pretreatment before modification, and the pretreatment includes ultrasonic treatment with an acid solution, water and anhydrous ethanol in sequence and then drying.

3. The preparation method according to claim 2, characterized in that The acidic solution is a dilute hydrochloric acid solution, and the mass fraction of the dilute hydrochloric acid solution is 1% to 10%.

4. The preparation method according to claim 1, characterized in that The nickel foam further includes iron oxide loading before modification, and the iron oxide loading includes the following steps: The nickel foam is immersed in a soluble iron salt solution and then dried to obtain a nickel foam with iron salt loaded on the surface; The nickel foam with the iron salt loaded on the surface is calcined to obtain the nickel foam with the iron oxide loaded on the surface.

5. The preparation method according to claim 4, characterized in that The calcination temperature is 200-600° C., and the calcination time is 0.5-2 h.

6. The preparation method according to claim 4, characterized in that The soluble iron salt in the soluble iron salt solution includes ferric nitrate or ferric chloride.

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