Device for producing hydrogen by electrolyzing water step by step based on alkaline phenazine aqueous organic flow battery

Abstract

The invention belongs to the technical field of water electrolysis, and particularly relates to a step-by-step water electrolysis hydrogen production device based on an alkaline phenazine aqueous organic flow battery. The device comprises a diaphragm electrolytic cell, a hydrogen evolution unit, an oxygen evolution unit and an electrolyte, phenazine which is substituted by different functional groups and has low oxidation-reduction potential is dissolved in an alkali solution to serve as a catholyte; the hexacyanoferrate is dissolved in alkali to serve as an anode electrolyte. The alkaline phenazine aqueous organic flow battery is coupled with a hydrogen evolution and oxygen evolution reaction, and water is electrolyzed to charge the flow battery and produce hydrogen and oxygen, so that hydrogen and oxygen are separated out in different spaces, and high-purity hydrogen is prepared. In addition, hydrogen and oxygen can be prepared simultaneously or asynchronously, and electrolysis is more flexible. The flowing medium is used as a medium for electrolyzing water step by step, the hydrogen production efficiency can be adjusted by controlling the amount of the electrolyte, and the hydrogen storage liquid can produce hydrogen in different places.

Description

Technical Field

[0001] The invention belongs to the technical field of water electrolysis, and specifically relates to a device for producing hydrogen by step-by-step electrolysis of water based on an alkaline phenazine aqueous organic liquid flow battery system. Background Art

[0002] Fossil energy is widely used around the world, but this highly polluting, non-renewable energy has brought tremendous pressure to the environment. The mining and use of coal, oil and natural gas not only leads to a large amount of greenhouse gas emissions, but also causes serious air and water pollution. With the continuous growth of global energy demand, mankind urgently needs to find alternative energy sources to achieve sustainable development and environmental protection. Hydrogen energy, as a clean energy, is considered to be one of the most promising energy sources in the future because it only produces water without pollutants after combustion. The widespread application of hydrogen energy can not only significantly reduce the emission of carbon dioxide and other pollutants, but also improve the efficiency of energy utilization. Therefore, hydrogen energy replacing fossil energy has become an important research direction in academia and industry.

[0003] Water resources are widely distributed on the earth, and electricity generated by renewable energy sources such as wind power and solar energy also makes it possible to produce hydrogen by electrolysis of water. Hydrogen production by electrolysis of water is a clean and sustainable method of obtaining hydrogen because it only requires water and electricity and no harmful emissions are produced during the electrolysis process. However, traditional water electrolysis technology has the risk of mixing hydrogen and oxygen, especially under high pressure and high temperature conditions, the mixed gas may cause safety hazards. In addition, traditional electrolysis technology also has certain limitations when utilizing wind and solar energy with greater volatility.

[0004] In order to overcome these challenges, the inventors (Wang Yonggang, Xia Yongyao, Chen Long) designed a method and device for producing hydrogen by two-step electrolysis of water based on a three-electrode system (patent application number: 201510799110.3) and a device and method for producing hydrogen by two-step electrolysis of water with a three-electrode system and a double electrolyzer (patent application number: 201610164054.0) to achieve the electrolytic preparation of hydrogen and oxygen separated in time and space, avoiding the mixing of gases. However, the mediators of these two methods are solid electrodes, which are difficult to transport over long distances. In addition, the production of hydrogen and oxygen is separated in time, which requires twice the time of conventional water electrolysis to obtain the same amount of hydrogen. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a device for producing hydrogen by electrolyzing water in steps based on an alkaline phenazine aqueous organic liquid flow battery system, so that hydrogen and oxygen are produced separately in two different units at the same time, thereby efficiently obtaining high-purity hydrogen. At the same time, the liquid electrolyte is used as a redox mediator to achieve long-distance transportation of hydrogen storage carriers.

[0006] The present invention provides a device for producing hydrogen by electrolyzing water in steps based on an alkaline phenazine aqueous organic liquid flow battery, and its structure is shown in FIG. Figure 5 , specifically comprising: a diaphragm electrolyzer, a hydrogen evolution unit, an oxygen evolution unit and an electrolyte; wherein the diaphragm electrolyzer (divided into a cathode chamber and an anode chamber) is used for charging an alkaline phenazine aqueous organic flow battery, the hydrogen evolution unit and the oxygen evolution unit are used for producing hydrogen and oxygen respectively, and the electrolyte is used as an electron-coupled proton buffer (ECPB), which can store electrons and protons in the solution; wherein:

[0007] Phenazines with low redox potentials substituted with different functional groups are dissolved in an alkaline solution with a concentration of 0.1 to 3 mol / L as the catholyte;

[0008] Hexacyanoferrite is dissolved in an alkaline solution at a concentration of 0.1 to 3 mol / L as the anolyte;

[0009] The device divides water electrolysis into two stages: charging the flow battery and producing hydrogen and oxygen.

[0010] In the first stage, during charging, phenazine in the cathode chamber of the diaphragm electrolyzer is reduced to dihydrogenated phenazine and introduced into the hydrogen evolution unit after 1 hour to 14 days; while hexacyanoferrous acid ions (Fe(CN)6 4- ) is oxidized to hexacyanoferrate (Fe(CN)6 3- ) and is introduced into the oxygen evolution unit at the same time.

[0011] In the second stage, in the hydrogen evolution unit, dihydrogenated phenazine is reduced to phenazine and circulated back to the cathode chamber of the diaphragm electrolyzer, while releasing hydrogen; in the oxygen evolution unit, Fe(CN)6 3- Reduced to Fe(CN)6 4- And circulate back to the anode chamber of the diaphragm electrolyzer, releasing oxygen at the same time.

[0012] In the present invention, the phenazine with low redox potential is a product in which the hydrogen atoms on the phenazine are substituted by electron-donating groups such as alkoxy, phenolic hydroxyl, alkylamine, alkyl, phenyl, etc., so that it is easily soluble in alkaline solution, and the redox potential is reduced to the potential of hydrogen evolution reaction (HER) in aqueous solution or even lower. Its structure is shown in formula (I)

[0013]

[0014] Wherein, R1 to R8 are each independently selected from -OH, -OC n H 2n+1 , -NHC n H2n+1 , -C n H 2n+1 , -OC n H 2n COOH, -NHC n H 2n COOH, -Ar, -C n H 2n Electron-donating groups such as COOH, n is a natural number;

[0015] Furthermore, the phenazines are typically classified into three categories;

[0016] (1) In the structural formula (I), R1 and R2 are -Ar, R3 is -OH, and R6 or R7 is -C n H 2n COOH; R4, R5, R8 are not present; it is denoted as BHPA; its structural formula is;

[0017]

[0018] (2) In the structural formula (I), R2 and R3 are -OC n H 2n+1 , R6 and R7 are -OH; R1, R4, R5, R8 are not present; it is recorded as DMeO-DHP; its structural formula is;

[0019]

[0020] (3) In the structural formula (I), R2 and R3 are -OC n H 2n+1 , R6 and R7 are -OC n H 2n COOH or -NHC n H 2n COOH; R1, R4, R5, R8 are not present; it is denoted as DMeO-DBAP; its structural formula is;

[0021]

[0022] Furthermore, the preparation of the BHPA and its derivatives is as follows:

[0023] 3,4-diaminophenylacetic acid and its derivatives are reacted with 2-hydroxy-1,4-naphthoquinone and its derivatives in an acetic acid solution at 40 to 80 degrees Celsius for 6 to 12 hours, and then filtered and dried to obtain BHPA and its derivatives; the structure and NMR spectrum of BHPA are shown in Figure 1 shown.

[0024] Furthermore, the preparation of the DMeO-DHP and its derivatives is as follows:

[0025] 1,2-dimethoxy-3,4-phenylenediamine and its derivatives and 2,5-dihydroxy-1,4-benzoquinone and its derivatives are refluxed in an aqueous solution for 6 to 24 hours, then filtered and dried to obtain DMeO-DHP and its derivatives; the structure and NMR spectrum of DMeO-DHP are shown in Figure 2 shown.

[0026] Furthermore, the preparation of the DMeO-DHP and its derivatives is as follows:

[0027] DMeO-DHP and its derivatives are refluxed with methyl bromobutyrate and its derivatives in N,N-dimethylformamide for 10 to 24 hours, then filtered, hydrolyzed, and the pH of the filtrate is adjusted so that the solid precipitates from the filtrate, then filtered, the filter cake is collected, and dried to obtain DMeO-DBAP and its derivatives. The structure and NMR spectrum of DMeO-DBAP are shown in Figure 3 shown.

[0028] The cyclic voltammograms of BHPA, DMeO-DHP and DMeO-DBAP are shown in Figure 4 shown.

[0029] In the present invention, the hexacyanoferrite can be selected from salts that are easily soluble in alkaline solutions, such as lithium hexacyanoferrite (Li4[Fe(CN)6]), sodium hexacyanoferrite (Na4[Fe(CN)6]), and potassium hexacyanoferrite (K4[Fe(CN)6]).

[0030] In the present invention, the hydrogen evolution unit is a chemical catalytic solid-liquid reaction tank, and the dihydrophenazine from the cathode chamber of the diaphragm electrolyzer is chemically catalytically oxidized to phenazine and circulated back to the cathode chamber of the diaphragm electrolyzer, while hydrogen ions are released to form hydrogen gas.

[0031] In the present invention, the oxygen evolution unit is a chemical catalytic solid-liquid reaction tank, and the Fe(CN)6 3- , is chemically reduced to Fe(CN)6 4- , and is circulated back to the anode chamber of the diaphragm electrolyzer, while the hydroxide is oxidized to oxygen.

[0032] In the present invention, the electrolyte may be lithium hydroxide, sodium hydroxide, or potassium hydroxide, with a concentration of 1 to 5 mol / L, preferably 2 mol / L.

[0033] In the present invention, the diaphragm of the diaphragm electrolyzer is selected from one of Nafion membrane, PBI membrane, SPEEK membrane, PAN membrane and PIM membrane.

[0034] In the present invention, the anode and cathode of the diaphragm electrolyzer are both one of graphite felt, carbon felt, carbon paper and carbon cloth.

[0035] In the present invention, in the chemical catalytic solid-liquid reaction tank, a hydrogen evolution catalyst catalyzes a solid-liquid chemical reaction, and the hydrogen evolution catalyst is:

[0036] Pt, Pd, Au or Ag and complexes thereof with carbon; or

[0037] A single substance or compound of Ni, Co, or Fe transition metal; or

[0038] Cu compounds; or

[0039] W; or

[0040] Mo compounds; or

[0041] C3N4 compound.

[0042] In the present invention, in the chemical catalytic solid-liquid reaction tank, an oxygen evolution catalyst catalyzes a solid-liquid chemical reaction, and the oxygen evolution catalyst is:

[0043] Ru, Ir or Pt precious metals, alloys and compounds; or

[0044] Ni, Co, Fe or Mn transition metals, either as a single substance or as a compound; or

[0045] N, S, P doped carbon; or

[0046] Bioelectrochemical catalysts such as laccase.

[0047] The present invention also provides an operating method of the above-mentioned device for producing hydrogen by step-by-step electrolysis of water based on alkaline phenazine aqueous organic liquid flow battery, the specific steps of which include:

[0048] (I) Charging of aqueous organic flow batteries in diaphragm electrolyzers:

[0049] In the diaphragm electrolyzer, phenazine in the cathode chamber is electrochemically reduced to dihydrophenazine, and Fe(CN)6 4- Electrochemically oxidized to Fe(CN)6 3- ; During this process, electrons are guided from the anode to the cathode through an external circuit, and at the same time, excess cations in the anode chamber diffuse through the membrane to the cathode chamber; subsequently, the electrolyte in the cathode chamber of the diaphragm electrolyzer is circulated to the hydrogen evolution unit, and the electrolyte in the anode chamber of the diaphragm electrolyzer is circulated to the oxygen evolution unit.

[0050] (II) Gas Generation

[0051] In the hydrogen evolution unit, dihydrophenazine is oxidized to phenazine on the hydrogen evolution catalyst, and the hydrogen ions are detached and reduced to hydrogen. The solution in the hydrogen evolution unit is then circulated to the cathode chamber of the diaphragm electrolyzer; in the oxygen evolution unit, Fe(CN)6 3-The phenazine is reduced to phenazine on the oxygen evolution catalyst, and the hydroxide is oxidized to oxygen. The solution in the oxygen evolution unit is then circulated to the anode chamber of the diaphragm electrolyzer.

[0052] The charging process of the diaphragm electrolyzer and the chemical catalytic process of the chemical catalytic solid-liquid reaction tank can be carried out at different times or simultaneously.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The most notable feature of the electrolyzer designed in the present invention is that it utilizes an alkaline phenazine aqueous organic liquid flow battery system to decompose water electrolysis into two steps, so that hydrogen production and oxygen production are separated in space, and can be carried out simultaneously or at different times, thereby directly obtaining high-purity hydrogen, flexibly adjusting the hydrogen production efficiency, and realizing off-site hydrogen production from hydrogen storage liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The structure and NMR spectrum of BHPA.

[0056] Figure 2 The structure and NMR spectrum of DMeO-DHP.

[0057] Figure 3 The structure and NMR spectrum of DMeO-DBAP.

[0058] Figure 4 Cyclic voltammograms of BHPA, DMeO-DHP and DMeO-DBAP.

[0059] Figure 5 This is a diagram of the device for step-by-step electrolysis of water to produce hydrogen based on an alkaline phenazine aqueous organic liquid flow battery system.

[0060] Figure 6 This is a time-current diagram of simultaneous off-site hydrogen and oxygen production based on the BHPA aqueous organic liquid flow battery in Example 4.

[0061] Figure 7 This is a time-current diagram of simultaneous off-site hydrogen and oxygen production based on the DMeO-DHP aqueous organic liquid flow battery in Example 5.

[0062] Figure 8 This is a time-current diagram of the simultaneous off-site hydrogen and oxygen production based on the DMeO-DBAP aqueous organic liquid flow battery in Example 6.

[0063] Fig. 9 This is a time-current diagram of simultaneous off-site hydrogen and oxygen production based on the BHPA aqueous organic liquid flow battery in Example 7.

[0064] Fig.10 This is a time and production diagram of hydrogen production at different times and locations based on the BHPA aqueous organic liquid flow battery in Example 8. DETAILED DESCRIPTION

[0065] The present invention is further described below by way of embodiments in conjunction with the accompanying drawings.

[0066] Example 1, preparation of BHPA and its derivatives:

[0067] 3,4-diaminophenylacetic acid and its derivatives are reacted with 2-hydroxy-1,4-naphthoquinone and its derivatives in an acetic acid solution at 40 to 80 degrees Celsius for 6 to 12 hours, and then filtered and dried to obtain BHPA and its derivatives; the structure and NMR spectrum of BHPA are shown in Figure 1 shown.

[0068] Example 2, preparation of DMeO-DHP and its derivatives:

[0069] 1,2-dimethoxy-3,4-phenylenediamine and its derivatives and 2,5-dihydroxy-1,4-benzoquinone and its derivatives are refluxed in an aqueous solution for 6 to 24 hours, then filtered and dried to obtain DMeO-DHP and its derivatives; the structure and NMR spectrum of DMeO-DHP are shown in Figure 2 shown.

[0070] Example 3, preparation of DMeO-DHP and its derivatives:

[0071] DMeO-DHP and its derivatives are refluxed with methyl bromobutyrate and its derivatives in N,N-dimethylformamide for 10 to 24 hours, then filtered, hydrolyzed, and the pH of the filtrate is adjusted so that the solid precipitates from the filtrate, then filtered, the filter cake is collected, and dried to obtain DMeO-DBAP and its derivatives. The structure and NMR spectrum of DMeO-DBAP are shown in Figure 3 shown.

[0072] The cyclic voltammograms of BHPA, DMeO-DHP and DMeO-DBAP are shown in Figure 4 shown.

[0073] Example 4: Simultaneous off-site hydrogen production based on BHPA aqueous organic liquid flow battery.

[0074] 3,4-diaminophenylacetic acid and 2-hydroxy-1,4-naphthoquinone were reacted in an acetic acid solution at 50 degrees Celsius for 8 hours at an equivalent ratio of 1:1, and then filtered and dried to obtain BHPA.

[0075] The diaphragm is made of 10 square centimeters of Nafion117, the electrolytic cell electrode is made of 10 square centimeters of heat-treated carbon cloth, the cathode electrolyte is 20 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L BHPA, the anolyte is 40 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L K4[Fe(CN)6], the hydrogen evolution unit is placed with a platinum-plated nickel mesh, and the oxygen evolution unit is placed with foam nickel. The cathode electrolyte circulates between the cathode chamber of the diaphragm electrolyzer and the hydrogen evolution unit, and the anolyte circulates between the anode chamber of the diaphragm electrolyzer and the oxygen evolution unit. At 25 degrees Celsius, constant voltage charging is performed at a voltage of 1.6V. No gas is generated in the initial state, and the current is 2500 mA. As the charging process proceeds, there are enough dihydrophenazine and Fe(CN)6 in the system. 3- The system starts to produce hydrogen and oxygen in the hydrogen evolution unit and oxygen evolution unit respectively with a current of 500 mA ( Figure 6 ).

[0076] Example 5: Simultaneous off-site hydrogen production based on DMeO-DHP aqueous organic liquid flow battery.

[0077] 1,2-dimethoxy-3,4-phenylenediamine and 2,5-dihydroxy-1,4-benzoquinone were refluxed in an aqueous solution at an equivalent ratio of 1:1 for 10 hours, and then filtered and dried to obtain DMeO-DHP.

[0078] The diaphragm is made of 10 square centimeters of Nafion117, the electrolytic cell electrode is made of 10 square centimeters of heat-treated carbon cloth, the cathode electrolyte is 20 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L DMeO-DHP, the anolyte is 40 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L K4[Fe(CN)6], the hydrogen evolution unit is placed with a platinum-plated nickel mesh, and the oxygen evolution unit is placed with foam nickel. The cathode electrolyte circulates between the cathode chamber of the diaphragm electrolyzer and the hydrogen evolution unit, and the anolyte circulates between the anode chamber of the diaphragm electrolyzer and the oxygen evolution unit. At 25 degrees Celsius, constant voltage charging is performed at a voltage of 1.6V. No gas is generated in the initial state, and the current is 2750 mA. As the charging process proceeds, there are enough dihydrophenazine and Fe(CN)6 in the system. 3- The system starts to produce hydrogen and oxygen in the hydrogen evolution unit and oxygen evolution unit respectively with a current of 620 mA ( Figure 7 ).

[0079] Example 6, simultaneous off-site hydrogen production based on DMeO-DBAP aqueous organic liquid flow battery.

[0080] DMeO-DHP and methyl bromobutyrate were refluxed in N,N-dimethylformamide at an equivalent ratio of 1:3 for 16 hours, then filtered and hydrolyzed, and the pH of the filtrate was adjusted to 5, so that the filtrate solid precipitated and then filtered, the filter cake was collected, and DMeO-DBAP was dried.

[0081] The diaphragm is made of 10 square centimeters of Nafion212, the electrolytic cell electrode is made of 10 square centimeters of heat-treated carbon cloth, the cathode electrolyte is 20 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L DMeO-DBAP, the anolyte is 40 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L K4[Fe(CN)6], the hydrogen evolution unit is placed with a platinum-plated nickel mesh, and the oxygen evolution unit is placed with foam nickel. The cathode electrolyte circulates between the cathode chamber of the diaphragm electrolyzer and the hydrogen evolution unit, and the anolyte circulates between the anode chamber of the diaphragm electrolyzer and the oxygen evolution unit. At 25 degrees Celsius, constant voltage charging is performed at a voltage of 1.6V. No gas is generated in the initial state, and the current is 2700 mA. As the charging process proceeds, there are enough dihydrophenazine and Fe(CN)6 in the system. 3- The system starts to produce hydrogen and oxygen in the hydrogen evolution unit and oxygen evolution unit respectively with a current of 570 mA ( Figure 8 ).

[0082] Example 7, simultaneous off-site hydrogen production based on BHPA aqueous organic liquid flow battery.

[0083] 3,4-diaminophenylacetic acid and 2-hydroxy-1,4-naphthoquinone are reacted in an acetic acid solution at 60 degrees Celsius for 6 hours at an equivalent ratio of 1:1, and then filtered and dried to obtain BHPA.

[0084] The diaphragm is made of 10 square centimeters of PIM membrane, the electrolytic cell electrode is made of 10 square centimeters of heat-treated carbon cloth, the cathode electrolyte is 20 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L BHPA, and the anolyte is 40 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L K4[Fe(CN)6]. The hydrogen evolution unit is placed with a platinum-plated nickel mesh, and the oxygen evolution unit is placed with foam nickel. The cathode electrolyte circulates between the cathode chamber of the diaphragm electrolyzer and the hydrogen evolution unit, and the anolyte circulates between the anode chamber of the diaphragm electrolyzer and the oxygen evolution unit. At 45 degrees Celsius, constant voltage charging is performed at a voltage of 1.6V. No gas is generated in the initial state, and the current is 5400 mA. As the charging process proceeds, there are enough dihydrophenazine and Fe(CN)6 in the system. 3- The system starts to produce hydrogen and oxygen in the hydrogen evolution unit and oxygen evolution unit respectively with a current of 1300 mA ( Fig. 9 ).

[0085] Example 8: Hydrogen production at different times and locations based on BHPA aqueous organic liquid flow battery.

[0086] 3,4-diaminophenylacetic acid and 2-hydroxy-1,4-naphthoquinone are reacted in an acetic acid solution at 60 degrees Celsius for 6 hours at an equivalent ratio of 1:1, and then filtered and dried to obtain BHPA.

[0087] The diaphragm is made of 10 square centimeters of Nafion117, the electrolyzer electrode is made of 10 square centimeters of heat-treated carbon cloth, the cathode electrolyte is 10 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L BHPA, the anolyte is 20 ml of 2 mol / L sodium hydroxide solution containing 0.5 mol / L K4[Fe(CN)6], the hydrogen evolution unit is placed with a platinum carbon catalyst, and the oxygen evolution unit is placed with nickel foam. The cathode electrolyte is not circulated, and the anolyte circulates between the anode chamber of the diaphragm electrolyzer and the oxygen evolution unit. At 25 degrees Celsius, a constant voltage charge of 1.6V is used until phenazine is completely reduced to dihydrogenated phenazine, at which time the oxygen evolution unit produces oxygen. The reduced BHPA solution is then injected into the hydrogen evolution unit, and the hydrogen evolution unit produces 60 ml of hydrogen within 8 minutes, and finally a total of 95.1 ml of hydrogen is produced. After reduction, 10 ml of 0.5 mol / L BHPA stores a total of 123.5 ml of hydrogen, and the Faraday efficiency of hydrogen production is 76.9%.

Claims

1. A device for producing hydrogen by step-by-step electrolysis of water based on alkaline phenazine aqueous organic liquid flow batteries, characterized in that include: a diaphragm electrolyzer, a hydrogen evolution unit, an oxygen evolution unit and an electrolyte; The diaphragm electrolyzer is used for charging the alkaline phenazine aqueous organic flow battery, the hydrogen evolution unit and the oxygen evolution unit are used for producing hydrogen and oxygen respectively, and the electrolyte is used as an electron coupled proton buffer (ECPB) to store electrons and protons in the solution; wherein: The cathode electrolyte is obtained by dissolving phenazines with low redox potential substituted with different functional groups in an alkaline solution, and the concentration is 0.1-3 mol / L; The anolyte is obtained by dissolving hexacyanoferrite in an alkaline solution, and the concentration is 0.1 to 3 mol / L; The device divides the electrolysis of water into two stages: charging of the flow battery and production of hydrogen and oxygen: In the first stage, during charging, phenazine in the cathode chamber of the diaphragm electrolyzer is reduced to dihydrogenated phenazine and introduced into the hydrogen evolution unit after 1 hour to 14 days; while hexacyanoferrous acid ion (Fe(CN)6 4- ) is oxidized to hexacyanoferrate (Fe(CN)6 3- ), and is simultaneously introduced into the oxygen evolution unit; In the second stage, in the hydrogen evolution unit, dihydrogenated phenazine is reduced to phenazine and circulated back to the cathode chamber of the diaphragm electrolyzer, while releasing hydrogen; in the oxygen evolution unit, Fe(CN)6 3- Reduced to Fe(CN)6 4- And circulate back to the anode chamber of the diaphragm electrolyzer, releasing oxygen at the same time.

2. The device according to claim 1, characterized in that The low redox potential phenazine is a product of replacing the hydrogen atoms on phenazine with alkoxy, phenolic hydroxyl, alkylamine, alkyl, or phenyl electron-donating groups, so that it is easily soluble in alkaline solution and its redox potential is reduced to the potential of hydrogen generation reaction in aqueous solution or even lower. Its structure is shown in formula (I) Wherein, R1 to R8 are each independently selected from -OH, -OC n H 2n+1 , -NHC n H 2n+1 , -C n H 2n+1 , -OC n H 2n COOH, -NHC n H 2n COOH, -Ar, -C n H 2n COOH and other electron donating groups, n is a natural number.

3. The device according to claim 2, characterized in that The phenazines are selected from the following three types: (1) In the structural formula (I), R1 and R2 are -Ar, R3 is -OH, and R6 or R7 is -C n H 2n COOH; denoted as BHPA; its structural formula is; (2) In the structural formula (I), R2 and R3 are -OC n H 2n+1 , R6 and R7 are -OH; recorded as DMeO-DHP; its structural formula is; (3) In the structural formula (I), R2 and R3 are -OC n H 2n+1 , R6 and R7 are -OC n H 2n COOH or -NHC n H 2n COOH; denoted as DMeO-DBAP; its structural formula is; 4. The device according to claim 1, characterized in that The hexacyanoferrite is selected from lithium hexacyanoferrite, sodium hexacyanoferrite or potassium hexacyanoferrite.

5. The device according to claim 1, characterized in that The hydrogen evolution unit is a chemical catalytic solid-liquid reaction tank, and the dihydrophenazine from the cathode chamber of the diaphragm electrolyzer is chemically catalytically oxidized to phenazine and circulated back to the cathode chamber of the diaphragm electrolyzer, while hydrogen ions are released to form hydrogen gas.

6. The device according to claim 1, characterized in that The oxygen evolution unit is a chemical catalytic solid-liquid reaction tank, and the Fe(CN)6 3- , is chemically reduced to Fe(CN)6 4- , and is circulated back to the anode chamber of the diaphragm electrolyzer, while the hydroxide is oxidized to oxygen.

7. The device according to claim 1, characterized in that The electrolyte is selected from lithium hydroxide, sodium hydroxide and potassium hydroxide, and the concentration is 1-5 mol / L.

8. The device according to claim 1, characterized in that The diaphragm of the diaphragm electrolyzer is selected from one of Nafion membrane, PBI membrane, SPEEK membrane, PAN membrane and PIM membrane.

9. The device according to claim 1, characterized in that The anode and cathode of the diaphragm electrolyzer are both one of graphite felt, carbon felt, carbon paper and carbon cloth.

10. The device according to claim 1, characterized in that: The chemical catalytic solid-liquid reaction tank carries out a hydrogen evolution catalyst catalyzed solid-liquid chemical reaction, and the hydrogen evolution catalyst used is: Pt, Pd, Au or Ag and a composite thereof with carbon; or A single substance or compound of Ni, Co, or Fe transition metal; or Cu compounds; or W compound; or Mo compounds; or C3N4 compounds; The chemical catalytic solid-liquid reaction tank carries out a solid-liquid chemical reaction catalyzed by an oxygen evolution catalyst, and the oxygen evolution catalyst used is: Ru, Ir or Pt noble metals, alloys and compounds; or Ni, Co, Fe or Mn transition metals, either as a single substance or as a compound; or N, S, P doped carbon; or Bioelectrochemical catalysts.

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