Electrode for hydrogen production from seawater, preparation method and application thereof

Abstract

The application provides a seawater hydrogen production electrode, which comprises a substrate and a catalytic layer combined on the surface of the substrate, wherein the catalytic layer is obtained through metal corrosion and in-situ deposition reaction of the substrate in a solution containing chloride ions; the application also provides a preparation method and application of the electrode. The catalyst layer of the application forms in chloride ions, forms a reaction equilibrium with chloride ions in seawater, can stably exist in chloride ions, avoids the adverse effects of seawater chlor-oxidation, has high stability in seawater electrolysis hydrogen production, and can simultaneously catalyze hydrogen production and oxygen production reactions and has selectivity. The electrode provided by the application can be applied to an electrolytic hydrogen production system and can directly electrolyze seawater, avoids the limitation of electrolytic hydrogen production application caused by lack of fresh water resources, reduces electrolytic hydrogen production cost, and expands the application range of electrolytic hydrogen production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolytic hydrogen production, in particular to a seawater hydrogen production electrode, a preparation method and application thereof. BACKGROUND

[0002] Water is an abundant natural resource, which accounts for about 71% of the earth's surface. Among them, seawater accounts for 96.5% of the total water on earth. Unlike fresh water, its composition is very complex, involving 92 chemical substances and elements.

[0003] The large amount of impurities such as ions, microorganisms and particles in seawater can cause problems such as side reaction competition, catalyst deactivation, and membrane blockage during hydrogen production. Therefore, two different technical routes of seawater direct hydrogen production and seawater indirect hydrogen production are formed for hydrogen production from seawater. The route of seawater direct hydrogen production is mainly prepared by electrolysis or photolysis of water; seawater indirect hydrogen production is to first desalinate seawater to form high-purity fresh water and then produce hydrogen, that is, the combination of seawater desalination technology and electrolysis, photolysis, pyrolysis and other hydrolysis hydrogen production technologies.

[0004] In order to expand the application range of electrolytic hydrogen production, it is of great significance to provide an electrode suitable for hydrogen production from seawater and a preparation method thereof. SUMMARY

[0005] The technical problem solved by the present application is to provide a seawater hydrogen production electrode, which is used for seawater electrolytic hydrogen production and has high stability and selectivity.

[0006] Therefore, the present application provides a seawater hydrogen production electrode, which comprises a substrate and a catalytic layer compounded on the surface of the substrate; the substrate is a porous or dense conductive metal material, and the catalytic layer is obtained by metal corrosion and in-situ deposition reaction of the substrate in a solution containing chloride ions.

[0007] Preferably, the surface of the substrate further comprises a loading layer of one or more metals.

[0008] Preferably, the substrate is selected from one or more of iron, nickel, cobalt and molybdenum.

[0009] The present application also provides a preparation method of a seawater hydrogen production electrode, comprising the following steps:

[0010] A) pretreating the substrate;

[0011] B) soaking and reacting the substrate obtained in step A) in a solution containing chloride ions.

[0012] Preferably, step A) is specifically:

[0013] The substrate is sequentially washed by water, dilute hydrochloric acid and anhydrous ethanol; the concentration of the dilute hydrochloric acid is 0.05-0.5 mol / L.

[0014] Preferably, the solution containing chloride ions is sodium chloride aqueous solution or seawater.

[0015] Preferably, the concentration of the sodium chloride aqueous solution is 0.1-0.5 mol / L; the seawater further comprises 1-5 wt% of scale inhibitor.

[0016] Preferably, the soaking time is 12 hours or more.

[0017] The application further provides a method for producing hydrogen from seawater, comprising:

[0018] The electrode or the electrode prepared by the preparation method is placed in seawater for electrolysis.

[0019] Preferably, the current density of the electrolysis is 100-200 mA / cm 2 , the voltage is 1.2-2.0 V, and the time is 36-72 h.

[0020] The application provides an electrode for producing hydrogen from seawater, comprising a substrate and a catalytic layer combined on the surface of the substrate, wherein the catalytic layer is obtained by metal corrosion and in-situ deposition reaction of the substrate in a solution containing chloride ions; the catalyst layer of the application forms in chloride ions, forms a reaction equilibrium with chloride ions in seawater, can stably exist in chloride ions, avoids the adverse effects of seawater chlor-oxidation, has high stability in seawater electrolysis for producing hydrogen, can simultaneously catalyze hydrogen production and oxygen production reactions, and has selectivity. The electrode provided by the application can be applied to an electrolysis system for producing hydrogen, can directly electrolyze seawater, avoids the limitation of lack of fresh water resources on the application of electrolysis for producing hydrogen, reduces the cost of electrolysis for producing hydrogen, and expands the application range of electrolysis for producing hydrogen. DETAILED DESCRIPTION

[0021] In order to further understand the application, the preferred embodiments of the application are described below in conjunction with examples, but it should be understood that the description is only for further illustrating the features and advantages of the application, and is not a limitation on the claims of the application.

[0022] In view of the application demand of electrolysis of water for producing hydrogen in the prior art, the application provides an electrode for producing hydrogen from seawater, which has high stability and selectivity as an electrode material for electrolysis of seawater for producing hydrogen. Specifically, the application discloses an electrode for producing hydrogen from seawater, comprising a substrate and a catalytic layer combined on the surface of the substrate; the substrate is a porous or dense conductive metal material, and the catalytic layer is obtained by metal corrosion and in-situ deposition reaction of the substrate in a solution containing chloride ions.

[0023] In the electrode provided by the present application, the substrate is specifically selected from one or more of iron, nickel, cobalt and molybdenum; the substrate can also be a composite with a layer of foreign metal loaded on the surface, and the catalytic layer can comprise one or more metals, so that the catalytic layer formed is a nanocomposite of the substrate metal and the foreign metal. In the present application, the substrate is a nickel foam or a nickel metal sheet loaded with iron.

[0024] In view of the electrode for hydrogen production from seawater provided by the present application, the present application also provides a preparation method of the electrode, comprising the following steps:

[0025] A) pretreating the substrate;

[0026] B) soaking and reacting the substrate obtained in step A) in a solution containing chloride ions.

[0027] In the preparation process, the substrate is first pretreated, and the pretreatment is to sequentially wash the substrate with water, dilute hydrochloric acid and anhydrous ethanol; the concentration of the dilute hydrochloric acid is 0.05-0.5 mol / L.

[0028] After the pretreatment of the substrate, it is soaked and reacted in a solution containing chloride ions; in the reaction process, the chloride ions do not consume, and accelerate the corrosion process in the form of reducing ohmic resistance, promoting the combination of anions and cations, and promoting the migration of products. In this process, if the catalytic layer is formed on both surfaces of the substrate, it is directly placed in the above-mentioned solution, and if the catalytic layer is formed on one surface of the substrate, the substrate is placed on a support, the support is placed in a sodium chloride solution or a seawater container, so that the lower surface of the substrate contacts the solution and the upper surface contacts air. In the present application, the solution containing chloride ions can be an aqueous sodium chloride solution or seawater; the concentration of the aqueous sodium chloride solution is 0.1-0.5 mol / L, and the seawater further comprises 1-5 wt% of a scale inhibitor, which is well known to those skilled in the art and is not particularly limited in the present application. The above-mentioned concentration of the aqueous sodium chloride solution or seawater will cause the surface of the substrate to corrode and form a catalytic layer. The addition of the scale inhibitor can deposit a scale-inhibiting layer on the surface of the substrate to prevent the deposition of calcium and magnesium ions in seawater and selectively deposit iron. The soaking time is more than 12 hours.

[0029] The present application also provides a method for hydrogen production from seawater, comprising:

[0030] placing the above-mentioned electrode in seawater for electrolysis.

[0031] In the above-mentioned process, the current density of the electrolysis is 100-200 mA / cm 2 , the voltage is 1.2-2.0 V, and the time is 36-72 h.

[0032] The application forms a bifunctional seawater hydrogen production catalytic layer on the surface of a metal substrate, and utilizes existing chloride ions in a solution or seawater to realize catalyst preparation through a corrosion process, which is simple and low in cost. The catalyst produced in the corrosion process forms in the chloride ions and forms a reaction equilibrium with the chloride ions in seawater, which can stably exist in the chloride ions and avoids the adverse effects of seawater chlor-oxidation. The catalyst formation and seawater hydrogen production are continuously carried out, which simplifies the overall process flow.

[0033] In order to further understand the application, the electrode for seawater hydrogen production, the preparation method thereof and the application thereof provided by the application are described in detail below in combination with examples, and the protection scope of the application is not limited by the following examples.

[0034] Example 1

[0035] The embodiment provides an electrode suitable for hydrogen production using seawater as raw material and a preparation method thereof.

[0036] The electrode comprises a substrate and a catalytic layer; the substrate is foamed nickel, and the catalytic layer is located on the double-sided surface of the substrate.

[0037] The preparation method of the electrode is as follows:

[0038] 1. The substrate is pretreated by washing with water, dilute hydrochloric acid and anhydrous ethanol in sequence, and the concentration of the dilute hydrochloric acid is 0.1 mol / L.

[0039] 2. The catalytic layer is formed by immersing the substrate in a 0.1 mol / L sodium chloride solution for more than 12 hours.

[0040] In the above preparation method, metal corrosion and in-situ deposition reactions occur in the process of forming the catalytic layer, and the specific mechanism is as follows:

[0041] Ni = Ni 2+ + 2e - ;

[0042] Ni = Ni 3+ + 3e -

[0043] Ni 2+ + 2H2O = Ni(OH)2 + 2H + ;

[0044] Ni 3+ + 3H2O = Ni(OH)3 + 3H + ;

[0045] In the corrosion process, the presence of chloride ions accelerates the corrosion process; in the deposition process, uniform and dispersed nickel metal hydroxide nanoparticles are formed on the surface of the substrate.

[0046] The prepared electrode was tested for hydrogen production via electrolysis in a flowing electrolyzer using seawater as the electrolyte at a speed of 100 mA / cm². 2 At the specified current density, the voltage of the electrolytic cell is 1.82V; at 1000mA / cm 2 After 72 hours of continuous operation at current density, the voltage decay rate is less than 1%.

[0047] Uncorroded and unactivated nickel electrodes, under the same conditions, at 100 mA / cm 2 At the given current density, the voltage of the electrolytic cell is 2.06V; at 1000mA / cm 2 After 12 hours of continuous operation at current density, the voltage decay rate reaches 10%.

[0048] Example 2

[0049] This embodiment provides an electrode suitable for hydrogen production from seawater and its preparation method:

[0050] The electrode includes a substrate and a catalyst layer; the substrate is a nickel metal sheet with an iron-loaded layer on its surface, the iron-loaded layer has a thickness of 5 nm, the nickel metal sheet has a thickness of 100 micrometers, and the catalyst layer is located on one side of the substrate with the iron-loaded layer.

[0051] The electrode is prepared by:

[0052] 1. Matrix pretreatment: The matrix was washed sequentially with water, dilute hydrochloric acid, and anhydrous ethanol. The concentration of dilute hydrochloric acid was 0.05 mol / L.

[0053] 2. Catalytic layer formation: Immerse the substrate in 0.5 mol / L sodium chloride solution for more than 12 hours; place the substrate on the support with the loaded layer facing down; place the support in a sodium chloride solution or seawater container so that the lower surface of the substrate is in contact with the solution and the upper surface is in contact with the air;

[0054] In the above preparation method, metal corrosion and in-situ deposition reactions occur during the formation of the catalyst layer. The specific mechanism is as follows:

[0055] M = M 2+ +2e - ;

[0056] M = M 3+ +3e - (M represents metallic elements, namely iron and nickel);

[0057] xM1 3+ +yM2 2+ +(3x+2y+z)H2O——>xM1(OH)3-yM2(OH)2-zH2O+(3x+2y)H + (M1 and M2 represent the base metal elements, M1 is iron and M2 is nickel);

[0058] The layered double metal hydroxide has a large specific surface area and porosity, and the synergistic effect between the double metals improves the activity performance of the catalyst.

[0059] The prepared electrode was subjected to electrolysis for hydrogen production test in a flow electrolysis cell, the electrolyte was seawater, the voltage of the electrolysis cell was 1.73 V at 100 mA / cm 2 The voltage of the electrolysis cell was 1.98 V at 1000 mA / cm 2 The voltage attenuation rate was less than 1% when continuously working at 1000 mA / cm 2 The voltage of the electrolysis cell was 1.98 V at 1000 mA / cm 2 The voltage attenuation rate reached 10% when continuously working at 1000 mA / cm

[0060] The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be noted that for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0061] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A seawater hydrogen production electrode, comprising a substrate and a catalytic layer complexed on the surface of the substrate; the substrate is a porous or dense conductive metal material selected from a nickel foam, and the catalytic layer is obtained by metal corrosion and in-situ deposition reaction of the substrate in a solution containing chloride ions, forming uniformly dispersed nickel hydroxide nanoparticles. The solution containing chloride ions is an aqueous sodium chloride solution or seawater, and the concentration of the aqueous sodium chloride solution is 0.1-0.5 mol / L. The preparation method of the seawater hydrogen production electrode comprises the following steps: A) pretreating the substrate; B) soaking and reacting the substrate obtained in step A) in a solution containing chloride ions; The soaking time is more than 12 hours.

2. The electrode of claim 1, wherein The surface of the substrate further comprises a loading layer of one or more metals.

3. The electrode of claim 1, wherein Step A) specifically comprises: The substrate is sequentially washed with water, dilute hydrochloric acid and anhydrous ethanol; the concentration of the dilute hydrochloric acid is 0.05-0.5 mol / L.

4. The method of claim 1, wherein, The seawater further comprises 1-5 wt% of a scale inhibitor.

5. A seawater hydrogen production method, comprising: placing the electrode of any one of claims 1-4 in seawater for electrolysis.

6. The method of claim 5, wherein, The current density of the electrolysis is 100-200 mA / cm 2 , the voltage is 1.2-2.0 V, and the time is 36-72 h.