Function sequence integrated carbon anode assisted water electrolysis hydrogen production method

Abstract

The invention discloses a function sequence integrated carbon anode assisted water electrolysis hydrogen production method, and belongs to the technical field of hydrogen energy production. The invention aims to solve the problems of high energy consumption and low hydrogen production efficiency of hydrogen production by water electrolysis in the prior art. According to the invention, a biomass material with a natural porous structure is used as a carbon anode, the carbon anode with an integrated structure is formed after high-temperature carbonization, and the anode has an orderly structured microscopic hierarchical structure, catalytic active sites and a conductive network. The design of the porous structure increases the specific surface area of the anode, and improves the contact efficiency and oxidation reaction rate of the electrolyte. And meanwhile, the conductive network in the anode reduces the electrode resistance, so that the energy consumption in the water electrolysis process is obviously reduced. By adjusting the pH environment of the interface, uniform distribution of OH <-> concentration is maintained, and local acidification is inhibited, so that the activity and stability of carbon oxidation reaction are improved. The invention provides a low-cost and sustainable solution for low-power-consumption carbon anode assisted water electrolysis hydrogen production.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen energy production, and relates to a method for producing hydrogen by low-power-consumption carbon-assisted water electrolysis. Background Art

[0002] As a clean and renewable energy source, hydrogen occupies an important position in the future carbon-neutral energy system. At present, hydrogen production technology by water electrolysis is becoming the main development direction in the field of hydrogen production due to its advantages such as cleanliness and high purity. However, in the traditional process of hydrogen production by water electrolysis, the anode oxygen evolution reaction (Oxygen Evolution Reaction, OER) has high energy consumption due to the existence of high thermodynamic and kinetic barriers, which limits the widespread application of this technology. Studies have shown that the carbon oxidation reaction (Carbon Oxidation Reaction, COR) can be used as an effective alternative to the anode oxygen evolution reaction. The oxidation behavior of carbon materials at the anode of water electrolysis can reduce the voltage and energy consumption of the hydrogen production process.

[0003] The patent "A method for producing hydrogen by electrolysis of water assisted by a self-supporting carbon anode" (CN 115466969B) proposes to prepare a self-supporting carbon anode by hydrothermal, tableting and annealing processes on biomass, and to use the direct electron transfer mechanism in the self-oxidation process of the carbon anode to significantly improve the electron transfer from OH – The transfer efficiency of ions to the carbon anode shows excellent carbon oxidation performance and auxiliary hydrogen production characteristics. However, the tableting process destroys the natural microstructure inherent in biomass, which seriously hinders the transmission of electrolyte on the surface and inside of the carbon anode. Especially at high current density, the OH on the carbon anode interface – The diffusion rate of ions is difficult to match the consumption rate, causing local acidification of the anode surface and significantly reducing the oxidation activity of carbon, thus affecting the efficiency and stability of hydrogen production. Traditionally, researchers have tried to increase the OH content in the electrolyte to – The initial concentration of ions can be reduced to mitigate the adverse effects of local acidification. However, the application of high-concentration alkaline electrolytes has many disadvantages, including significantly increased costs, serious electrolyte pollution, and strong corrosion to equipment.

[0004] In order to solve the above problems, the present invention selects biomass with natural vertically arranged channels as the carbon source, and prepares a functionally structured integrated carbon anode with a hierarchical structure and low-tortuosity channels through a simple annealing treatment, which fully promotes the OH – The diffusion of ions in the pores of the carbon anode significantly improves the COR activity and auxiliary hydrogen production characteristics of the carbon anode. The HER||COR system composed of a functionally sequenced integrated carbon anode can reach 200mA cm at 80°C with only 1.42V. –2The industrial-grade current density is more than 3.6 times the hydrogen production performance reported in the patent "A method for hydrogen production by electrolysis assisted by self-supporting carbon anode". The design of the functional sequence integrated carbon anode provides a new solution for carbon-assisted water electrolysis low-energy hydrogen production technology. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of high energy consumption and low hydrogen production efficiency in the prior art of water electrolysis hydrogen production, and to provide a method for water electrolysis hydrogen production assisted by a functional sequence integrated carbon anode.

[0006] The present invention provides a method for preparing a carbon material with integrated functional sequence, and using the carbon material as an anode, thereby improving the oxidation reaction efficiency of the carbon material through a microscopic hierarchical structure with integrated functional sequence and a multifunctional design, thereby achieving reduced energy consumption and improved hydrogen production efficiency in hydrogen production by electrolysis of water.

[0007] The present invention introduces a structured design into the carbon anode material, integrating an ordered porous structure, catalytic active sites and a conductive network; the porous structure increases the specific surface area of ​​the anode, significantly improves the contact between the carbon material and the electrolyte, and enhances the efficiency of the oxidation reaction; the catalytic active sites and the conductive network reduce the anode resistance, reduce the overpotential, and thus reduce the voltage required for electrolysis.

[0008] A method for producing hydrogen by electrolysis of water using a functionally sequenced integrated carbon anode is specifically accomplished by the following steps:

[0009] 1. drying the biomass with natural vertically arranged channels and then cutting it to obtain cut biomass;

[0010] 2. High temperature carbonization:

[0011] Under the protection of an inert gas atmosphere, the cut biomass is heated to 600°C to 2000°C, then carbonized at 600°C to 2000°C for a period of time, and naturally cooled to room temperature to obtain a functional structure integrated carbon anode;

[0012] 3. Functional structure integrated carbon anode assisted water electrolysis to produce hydrogen:

[0013] The functional sequence integrated carbon anode is used as the anode, and the electrode that can produce hydrogen evolution reaction is used as the cathode. The anode and the cathode are placed in an electrolytic cell, and then the electrolyte is added into the electrolytic cell to assemble a water electrolysis hydrogen production device, which is connected to a power supply to perform constant current or constant voltage water electrolysis to produce hydrogen at a fixed temperature.

[0014] The principle of the present invention is as follows:

[0015] In the present invention, in the traditional carbon anode assisted water electrolysis system, the OH- ions on the surface of the carbon anode are rapidly consumed, which significantly reduces the pH of the anode surface, resulting in local acidification in the reaction area, thereby affecting the overall efficiency of the carbon oxidation reaction. In order to overcome these limitations, the present invention focuses on adjusting the pH environment of the carbon anode interface through innovative structural design. Specifically, by using materials with natural porous structures (such as wood), a microscopic hierarchical structure can be provided for the electrode surface to make its local acid-base environment more stable. Through this structured design, the OH- concentration at the anode interface is evenly distributed, thereby reducing the acidification phenomenon and increasing the activity of the carbon oxidation reaction.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Compared with carbon anodes without microscopic hierarchical structures, this functionally ordered carbon anode forms a smooth channel network inside the electrode, effectively improving the charge transfer efficiency during the carbon oxidation reaction. This strategy does not require excessive reliance on high-concentration alkaline solutions, can achieve higher reaction efficiency while reducing operating costs, and provides a sustainable and practical engineering solution for carbon anode-assisted water electrolysis to produce hydrogen;

[0018] 2. The functional sequence integrated carbon anode prepared by the present invention can significantly reduce the power consumption of water electrolysis by assisting water electrolysis to produce hydrogen. At a voltage of 1.5V, the current density of water electrolysis can reach 240mA / cm 2 ; Functional sequence integrated carbon anode at 50mA / cm 2 After 37 hours of assisted water electrolysis to produce hydrogen at a current density of , the voltage slowly increased to 1.5V, proving that the functional sequence-integrated carbon anode can continuously assist water electrolysis to produce hydrogen at a low voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Graph showing the effect of different carbonization temperatures on the oxidation of the functional sequence integrated carbon anode, in which 1000°C is the functional sequence integrated carbon anode prepared in Example 1, 900°C is the functional sequence integrated carbon anode prepared in Example 2, 800°C is the functional sequence integrated carbon anode prepared in Example 3, 700°C is the functional sequence integrated carbon anode prepared in Example 4, and 600°C is the functional sequence integrated carbon anode prepared in Example 5;

[0020] Figure 2 : are AC impedance spectra of functional sequence integrated carbon anodes at different carbonization temperatures, in which 1000°C is the functional sequence integrated carbon anode prepared in Example 1, 900°C is the functional sequence integrated carbon anode prepared in Example 2, 800°C is the functional sequence integrated carbon anode prepared in Example 3, 700°C is the functional sequence integrated carbon anode prepared in Example 4, and 600°C is the functional sequence integrated carbon anode prepared in Example 5;

[0021] Figure 3 This is a comparison diagram of oxidation curves of the functionally sequenced integrated carbon anode prepared in Example 1 and the carbon anode without functionally sequenced integrated structure, in which 1 is the functionally sequenced integrated carbon anode prepared in Example 1, 2 is the carbon anode prepared from pine sawdust, 3 is a commercial glassy carbon electrode, and 4 is a commercial highly oriented pyrolytic graphite electrode;

[0022] Figure 4 Polarization curves of the functional sequence integrated carbon anode prepared in Example 1 at 1, 0.5, 0.25, and 0.1 mol / L KOH solutions;

[0023] Figure 5 Polarization curve of hydrogen production by electrolysis of water assisted by the functional sequence integrated carbon anode prepared in Example 6;

[0024] Figure 6 This is a stability test diagram of the functionally sequenced integrated carbon anode prepared in Example 6 to assist in the electrolysis of water to produce hydrogen. DETAILED DESCRIPTION

[0025] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0026] Specific implementation method 1: This implementation method is a method for producing hydrogen by electrolysis of water using a functionally sequenced integrated carbon anode, which is specifically completed in the following steps:

[0027] 1. drying the biomass with natural vertically arranged channels and then cutting it to obtain cut biomass;

[0028] 2. High temperature carbonization:

[0029] Under the protection of an inert gas atmosphere, the cut biomass is heated to 600°C to 2000°C, then carbonized at 600°C to 2000°C for a period of time, and naturally cooled to room temperature to obtain a functional structure integrated carbon anode;

[0030] 3. Functional structure integrated carbon anode assisted water electrolysis to produce hydrogen:

[0031] The functional sequence integrated carbon anode is used as the anode, and the electrode that can produce hydrogen evolution reaction is used as the cathode. The anode and the cathode are placed in an electrolytic cell, and then the electrolyte is added into the electrolytic cell to assemble a water electrolysis hydrogen production device, which is connected to a power supply to perform constant current or constant voltage water electrolysis to produce hydrogen at a fixed temperature.

[0032] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the biomass with natural vertically arranged channels in step 1 is one or more of pine, corn stalks, birch, basswood and balsa wood. The other steps are the same as those in specific implementation method 1.

[0033] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: the cut shape described in step 1 is one or more of a circle, a triangle, a pentagon, a hexagon and a punched polygon; the drying temperature described in step 1 is 80° C. to 100° C. The other steps are the same as specific implementation method 1 or 2.

[0034] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the inert gas in step 2 is nitrogen or argon, and the heating rate in step 3 is 2°C / min to 2000°C / min. The other steps are the same as those in specific embodiments 1 to 3.

[0035] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the carbonization time at 600° C. to 2000° C. in step 3 is 2 h to 6 h. The other steps are the same as those of specific embodiments 1 to 4.

[0036] Specific implementation method 6: This implementation method is different from specific implementation methods 1 to 5 in that: the constant current in step 3 is 1 mA to 3000 mA; the constant voltage in step 3 is 0.1 V to 30 V. The other steps are the same as those in specific implementation methods 1 to 5.

[0037] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the electrode capable of undergoing hydrogen evolution reaction in step 3 is a Pt mesh, a Pt sheet, a Ni electrode, a carbon cloth, a graphite felt or a cathode catalyst supported on a carrier. The other steps are the same as those of specific embodiments 1 to 6.

[0038] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the carrier of the cathode catalyst supported on the carrier is a Pt mesh, a Pt sheet, a Ni electrode, a carbon cloth or a graphite felt, and the cathode catalyst is a catalyst having a hydrogen evolution function. The other steps are the same as those of specific embodiments 1 to 7.

[0039] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the electrolyte described in step 3 is a KOH solution with a concentration of 0.001 mol / L to 10 mol / L, a KOH solution with a mass fraction of 1% to 60%, a H2SO4 solution with a concentration of 0.5 mol / L to 10 mol / L, or a PBS buffer solution. The other steps are the same as those of specific embodiments 1 to 8.

[0040] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the fixed electrolysis temperature in step 3 is 20° C. to 100° C. The other steps are the same as those in specific embodiments 1 to 9.

[0041] The following examples are used to verify the beneficial effects of the present invention:

[0042] Example 1: A method for producing hydrogen by electrolysis of water assisted by a functionally sequenced integrated carbon anode, which is specifically completed by the following steps:

[0043] 1. drying the biomass with natural vertically arranged channels at 80°C, and then cutting it into a size of 10 mm (length) × 10 mm (width) × 3 mm (height) to obtain cut biomass;

[0044] The biomass with natural vertically arranged channels in step 1 is pine wood;

[0045] 2. High temperature carbonization:

[0046] Under the protection of argon atmosphere, the cut biomass was heated to the carbonization temperature at a heating rate of 10°C / min, then carbonized at the carbonization temperature for 2h, and naturally cooled to room temperature to obtain a functional sequence integrated carbon anode;

[0047] The carbonization temperature described in step 2 is 1000°C;

[0048] 3. Functional structure integrated carbon anode assisted water electrolysis to produce hydrogen:

[0049] A functionally sequenced integrated carbon anode is used as the anode, and an electrode that can undergo hydrogen evolution reaction is used as the cathode. The anode and the cathode are placed in an electrolytic cell, and then an electrolyte is added into the electrolytic cell to assemble a water electrolysis hydrogen production device. After connecting a power source, constant voltage water electrolysis is performed to produce hydrogen at a fixed electrolysis temperature.

[0050] The constant voltage in step 3 is 2V;

[0051] The electrode capable of undergoing hydrogen evolution reaction in step 3 is a Pt mesh;

[0052] The electrolyte described in step 3 is a KOH solution with a concentration of 1 mol / L;

[0053] The fixed electrolysis temperature described in step 3 is an operating temperature range of the electrolytic cell of 80°C.

[0054] Example 2: The difference between this example and Example 1 is that the carbonization temperature in step 2 is 900° C. The other steps and parameters are the same as those in Example 1.

[0055] Example 3: The difference between this example and Example 1 is that the carbonization temperature in step 2 is 800° C. The other steps and parameters are the same as those in Example 1.

[0056] Example 4: This example is different from Example 1 in that the carbonization temperature in step 2 is 700° C. The other steps and parameters are the same as those in Example 1.

[0057] Example 5: This example is different from Example 1 in that the carbonization temperature in step 2 is 600° C. The other steps and parameters are the same as those in Example 1.

[0058] Example 6: The difference between this example and Example 1 is that in step 1, the biomass is cut according to the size of 30 mm (length) × 30 mm (width) × 30 mm (height) to obtain the cut biomass; in step 3,

[0059] In a three-electrode system, the functionally sequenced integrated carbon anode obtained in Examples 1 to 5 was used as the working electrode, the Pt sheet was used as the counter electrode, and the mercury / mercury oxide electrode was used as the reference electrode. The polarization curve of the working electrode was recorded by a BioLogic-VMP3 electrochemical workstation.

[0060] Figure 1 Graph showing the effect of different carbonization temperatures on the oxidation of the functional sequence integrated carbon anode, in which 1000°C is the functional sequence integrated carbon anode prepared in Example 1, 900°C is the functional sequence integrated carbon anode prepared in Example 2, 800°C is the functional sequence integrated carbon anode prepared in Example 3, 700°C is the functional sequence integrated carbon anode prepared in Example 4, and 600°C is the functional sequence integrated carbon anode prepared in Example 5;

[0061] from Figure 1 It can be seen that the activity order of the functionally ordered integrated carbon anode is Example 5> Example 4> Example 3> Example 2> Example 1. The functionally ordered integrated carbon prepared by carbonizing pine wood at 1000°C has excellent oxidation activity, at 10 / 100mA / cm 2 At a current density of , its potential is only 0.45 / 1.20V vs.RHE.

[0062] Figure 2 : are AC impedance spectra of functional sequence integrated carbon anodes at different carbonization temperatures, in which 1000°C is the functional sequence integrated carbon anode prepared in Example 1, 900°C is the functional sequence integrated carbon anode prepared in Example 2, 800°C is the functional sequence integrated carbon anode prepared in Example 3, 700°C is the functional sequence integrated carbon anode prepared in Example 4, and 600°C is the functional sequence integrated carbon anode prepared in Example 5;

[0063] from Figure 2 It can be seen that: with the increase of carbonization temperature, the conductivity of the carbon anode is enhanced, and the functional sequence integrated carbon anode prepared by carbonization at 1000°C in Example 1 has the best electron transfer ability.

[0064] Figure 3 This is a comparison diagram of oxidation curves of the functionally sequenced integrated carbon anode prepared in Example 1 and the carbon anode without functionally sequenced integrated structure, in which 1 is the functionally sequenced integrated carbon anode prepared in Example 1, 2 is the carbon anode prepared from pine sawdust, 3 is a commercial glassy carbon electrode, and 4 is a commercial highly oriented pyrolytic graphite electrode;

[0065] from Figure 3 It can be seen that the functionally ordered carbon anode with superior microstructure prepared in Example 1 exhibits great COR potential compared to the carbon anode prepared using pine sawdust as the carbon source, especially having a relatively lower potential at high current density.

[0066] Figure 4 Polarization curves of the functional sequence integrated carbon anode prepared in Example 1 at 1, 0.5, 0.25, and 0.1 mol / L KOH solutions;

[0067] from Figure 4 It can be seen that the functionally sequenced integrated carbon anode prepared in Example 1 still has a high carbon oxidation activity in a low concentration KOH solution.

[0068] The functionally ordered integrated carbon electrode prepared in Example 6 was used as the anode, the Pt electrode (1 mm×1 mm) was used as the cathode, and the 1 mol / L KOH solution was used as the electrolyte. The functionally ordered integrated carbon anode and the Pt cathode were placed in an electrolytic cell, and the electrolyte was added to the electrolytic cell to assemble a water electrolysis hydrogen production device. The water electrolysis hydrogen production test was carried out at an electrolysis temperature of 80°C and a voltage range of 0-1.8V. The electrode polarization curve is shown in FIG. Figure 5 As shown;

[0069] Figure 5 Polarization curve of hydrogen production by electrolysis of water assisted by the functional sequence integrated carbon anode prepared in Example 6;

[0070] from Figure 5 It can be seen that the functional sequence integrated carbon anode assisted water electrolysis to produce hydrogen can significantly reduce the power consumption of water electrolysis. At a voltage of 1.5V, the current density of water electrolysis can reach 240mA / cm 2 .

[0071] The functionally ordered integrated carbon electrode prepared in Example 6 was used as an anode, a Pt electrode (1 mm×1 mm) was used as a cathode, and a 1 mol / L KOH solution was used as an electrolyte. The functionally ordered integrated carbon anode and the Pt cathode were placed in an electrolytic cell, and the electrolyte was added to the electrolytic cell to assemble a water electrolysis hydrogen production device. The water electrolysis hydrogen production test was carried out at an electrolysis temperature of 80° C. and a constant current of 50 mA.

[0072] Figure 6 This is a stability test diagram of the functional sequence integrated carbon anode assisted water electrolysis hydrogen production prepared in Example 6;

[0073] from Figure 6 It can be seen that the functional sequence integrated carbon anode is at 50mA / cm 2 After assisted water electrolysis to produce hydrogen for 37 hours at a current density of , the voltage slowly increased to 1.5 V, proving that the functional sequence-integrated carbon anode can continuously assist water electrolysis to produce hydrogen at a low voltage.

Claims

1. A method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode, characterized in that The method is specifically completed according to the following steps:

1. drying the biomass with natural vertically arranged channels and then cutting it to obtain cut biomass; 2. High temperature carbonization: Under the protection of an inert gas atmosphere, the cut biomass is heated to 600°C to 2000°C, then carbonized at 600°C to 2000°C for a period of time, and naturally cooled to room temperature to obtain a functional structure integrated carbon anode; 3. Functional structure integrated carbon anode assisted water electrolysis to produce hydrogen: The functional sequence integrated carbon anode is used as the anode, and the electrode that can produce hydrogen evolution reaction is used as the cathode. The anode and the cathode are placed in an electrolytic cell, and then the electrolyte is added into the electrolytic cell to assemble a water electrolysis hydrogen production device, which is connected to a power supply and performs constant current or constant voltage water electrolysis to produce hydrogen at a fixed electrolysis temperature.

2. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that The biomass with natural vertically arranged channels described in step 1 is one or more of pine, corn stalks, birch, basswood and balsa wood.

3. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that The cut shape described in step one is one or more of a circle, a triangle, a pentagon, a hexagon and a punched polygon; the drying temperature described in step one is 80° C. to 100° C.

4. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that The inert gas described in step 2 is nitrogen or argon; the heating rate described in step 3 is 2°C / min to 2000°C / min.

5. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that In step 3, the carbonization time at 600°C to 2000°C is 2h to 6h.

6. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that The constant current described in step 3 is 1mA to 3000mA; the constant voltage described in step 3 is 0.1V to 30V.

7. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that The electrode capable of undergoing hydrogen evolution reaction in step 3 is a Pt mesh, a Pt sheet, a Ni electrode, a carbon cloth, a graphite felt or a cathode catalyst supported on a carrier.

8. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode as an auxiliary aid according to claim 7, characterized in that The carrier of the cathode catalyst loaded on the carrier is a Pt net, a Pt sheet, a Ni electrode, a carbon cloth or a graphite felt, and the cathode catalyst is a catalyst with a hydrogen evolution function.

9. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode according to claim 1, characterized in that The electrolyte described in step three is a KOH solution with a concentration of 0.001 mol / L to 10 mol / L, a KOH solution with a mass fraction of 1% to 60%, an H2SO4 solution with a concentration of 0.5 mol / L to 10 mol / L, or a PBS buffer solution.

10. The method for producing hydrogen by electrolysis of water using a functionally sequenced carbon anode as an auxiliary aid according to claim 1, characterized in that The fixed electrolysis temperature described in step 3 is 20°C to 100°C.

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