Preparation method and application of a catalyst for ethylene glycol electro-oxidation based on MOFs with low-valence active centers

Abstract

The application discloses a preparation method and application of a catalyst for ethylene glycol electro-oxidation based on MOFs with low-valence active centers. The preparation method comprises the following steps: respectively dissolving nickel chloride, sodium citrate and polyvinylpyrrolidone in deionized water to form solution 1, dissolving potassium ferricyanide in deionized water to form solution 2, and fully stirring to be clear and transparent. Under the condition of vigorous stirring, solution 1 is added dropwise into solution 2 to form solution 3. A piece of pretreated foamed nickel is added into solution 3, and hydrothermal reaction is carried out at 80 DEG C for 27 hours. After natural cooling, the foamed nickel with the catalyst is taken out, cleaned with deionized water and anhydrous ethanol for multiple times, and vacuum dried at 60 DEG C overnight. The catalyst material can be applied to an electrocatalyst for ethylene glycol electro-oxidation reaction in an alkaline electrolyte, and reconfiguration does not occur in the ethylene glycol electro-oxidation process. In the working condition, low-valence nickel sites are used as catalytic active centers, and the catalyst has extremely high selectivity and catalytic activity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalysts, and relates to a preparation method of a glycol electro-oxidation catalyst based on MOFs with low-valence active centers, and also relates to application of the catalyst in preparation of an oxygen evolution catalyst material and an oxygen-absorbing electrode. BACKGROUND

[0002] Currently, electrolysis of water driven by renewable energy is an important method for producing hydrogen. However, the theoretical potential of the anode oxygen evolution reaction (OER) is 1.23 V (vs. reversible hydrogen electrode, vs. RHE), which leads to extremely high anode voltage, consumes a large amount of energy, and also has the risk of explosion caused by mixing of hydrogen and oxygen in industrial application. Therefore, using a small molecule electro-oxidation reaction to replace OER is an important measure to reduce the consumption of the anode. The glycol electro-oxidation reaction (EGOR) has an extremely low theoretical potential (0.57 V vs. RHE), and its product is a non-gaseous substance with high added value. However, it is still a challenge to weaken the competition between OER and EGOR and achieve high single product selectivity at high potential and high current density.

[0003] In previous studies, non-noble metal catalysts have suitable C1 product desorption capacity, and therefore have high formic acid selectivity. So far, the design of most non-noble metal catalyst systems is related to catalyst reconstruction. The high-valence active sites brought by reconstruction have extremely high small molecule catalytic capacity, but the OER process is similar to such catalytic processes, leading to competition of the catalyst active sites at high potential and thus inevitable production of oxygen by-products and low product selectivity. Therefore, it will be a new breakthrough to protect the catalytic sites at high potential and large current density in a hydrogen production system, avoid the formation of competitive sites of EGOR and OER by catalyst reconstruction, and thus efficiently catalyze the glycol electro-oxidation reaction and improve the intrinsic activity of the catalyst. SUMMARY

[0004] The application is aimed at the above problems, and provides a preparation method of a glycol electro-oxidation catalyst based on MOFs with low-valence active centers, and application of the catalyst as an oxygen evolution catalytic material in an electrolysis reaction. The catalyst material can be applied to an electrocatalyst for glycol electro-oxidation reaction in an alkaline electrolyte, and the catalyst does not undergo reconstruction in the glycol electro-oxidation process, uses low-valence nickel sites as the catalytic active center under working conditions, and has extremely high selectivity and catalytic activity.

[0005] In order to achieve the above object, the technical scheme adopted by the application is as follows:

[0006] In the first aspect of the present application, a preparation method of an ethylene glycol electro-oxidation catalyst based on MOFs with low-valence active centers is provided, comprising the following steps:

[0007] (1) Cut the nickel foam into a suitable size, and sequentially ultrasonic in acetone, ethanol and a certain concentration of hydrochloric acid, and then continue to use ethanol for ultrasonic treatment for multiple times until the last ultrasonic treated ethanol solution is colorless and transparent without nickel ion residue;

[0008] (2) Weigh a certain amount of nickel chloride hexahydrate, sodium citrate and polyvinylpyrrolidone into deionized water, and stir until a transparent colorless solution is obtained;

[0009] (3) Weigh a certain amount of potassium ferricyanide into deionized water, and stir until a transparent colorless solution is obtained;

[0010] (4) Under vigorous stirring, drop the solution in step (2) into the solution in step (3) drop by drop;

[0011] (5) Transfer the solution obtained in step (4) into an inert material lining, and place a piece of the cleaned nickel foam obtained in step (1) in it;

[0012] (6) Place the lining in step (5) in a suitable steel sleeve, and place it in an 80℃ oven for hydrothermal reaction for 27 hours; after the steel sleeve is naturally cooled, take out the nickel foam and rinse it with deionized water and ethanol for multiple times, and then place it in a 60℃ vacuum oven for overnight drying to obtain an ethylene glycol electro-oxidation catalyst NiFe-sc-PBA.

[0013] The preferred process conditions of each step are as follows:

[0014] Preferably, in step (1), the concentration of hydrochloric acid is 3 mol / L, and the ultrasonic treatment time is 15 min; the cut shape of the nickel foam is approximately square; the ratio between the area of the cut nickel foam and the volume of the inert material lining is 16-20 cm 2 :100 mL.

[0015] Preferably, in step (2), the molar ratio of nickel chloride to sodium citrate is 3:5, and the average weight average molecular weight of polyvinylpyrrolidone is 58000;

[0016] The molar ratio of nickel chloride to potassium ferricyanide in steps (2) and (3) is 3:1, and the stirring time of the solution is 10 min.

[0017] Preferably, in step (5), the inert material lining is selected from a Teflon lining.

[0018] In the second aspect of the present application, an ethylene glycol electro-oxidation catalyst based on MOFs with low-valence active centers is provided, which is prepared by the above method.

[0019] The catalyst has regular morphology (regular hexahedron), does not undergo reconstruction in the process of ethylene glycol electro-oxidation, uses low-valence nickel as an active center, and achieves high catalytic activity and formic acid selectivity.

[0020] Under the condition of ethylene glycol electro-oxidation, the active site nickel remains stable in the form of divalent, and as an anode catalyst, exhibits excellent activity in catalyzing ethylene glycol electro-oxidation under alkaline conditions. The electrochemical test results show that only an ultra-low cell voltage of 1.48 V and 1.62 V is required to achieve a current density of 500 mA·cm -2 and 1000 mA·cm -2 , and has an extremely high formic acid Faraday efficiency (greater than 94.5%) in a wide potential range (1.45 V to 1.70 V).

[0021] It is prepared into an anion exchange membrane coupled with a hydrogen production anode electrode material, and the anion exchange membrane electrolyzer assembled thereby requires a voltage as low as 2.02 V and 2.15 V at a current density of 1.0 A·cm -2 and 1.5 A·cm -2 , and has a formic acid Faraday efficiency greater than 92% in a current density range of 0.2 to 1.8 A·cm -2 . Moreover, it can be stably operated for 500 hours at a step current density of 1.0 A·cm -2 and 1.5 A·cm -2 , without obvious attenuation.

[0022] Therefore, the third aspect of the present application provides application of the above-mentioned ethylene glycol electro-oxidation catalyst in preparation of an oxygen evolution electrode.

[0023] The fourth aspect of the present application provides an oxygen evolution anode electrode, comprising an anode carrier and a catalyst material loaded thereon, wherein the catalyst material is the ethylene glycol electro-oxidation catalyst prepared by any one of the above-mentioned methods.

[0024] The fifth aspect of the present application provides a method for electrolyzing water, which uses the above-mentioned oxygen evolution anode electrode as an anode.

[0025] Preferably, the anode electrolyte solution is a 1M KOH solution containing 1M ethylene glycol, and the cathode electrolyte solution is a 1M KOH solution.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) Most of the transition metal-based EGOR catalysts designed so far will restructure under harsh electro-oxidation environments to form (oxy)hydroxide active sites similar to the OER process, resulting in competition with OER. However, NiFe-sc-PBA will maintain Ni(II) active sites and will not restructure to NiOOH structure, thereby increasing the activity and selectivity of EGOR without producing O2, and providing high-value-added formate high-product selectivity. The stable Ni(II) can be stable in harsh alkaline electrolyte (3M KOH). This innovative strategy of designing low-valence active centers by simple hydrothermal synthesis provides a new idea for designing non-noble metal supported glycol electro-oxidation catalysts.

[0028] (2) The NiFe-sc-PBA prepared by the present application is one of the best non-noble metal EGOR electrocatalysts at present, with a potential of 1.48V and 1.62V at a current density of 500mA·cm -2 and 1000mA·cm -2 , and a faradic efficiency of formic acid as high as 98.6% at 1.45V, exceeding most of the latest reported alkaline EGOR electrocatalysts.

[0029] (3) The NiFe-sc-PBA prepared by the present application is used as an anode material to assemble a coupled hydrogen production anion exchange membrane electrolyzer, which reaches a current density of 1.0A·cm -2 and 1.5A·cm -2 at a cell voltage of about 2.02V and 2.15V, respectively, and the formic acid faradic efficiency is greater than 92% in the current density range of 0.2 to 1.8A·cm -2 . And it can be stably operated at a step current density of 1.0A·cm -2 and 1.5A·cm -2 for 500 hours without significant attenuation. Compared with the coupled hydrogen production electrolyzer using non-noble metal materials as anode electrocatalysts, it reaches the leading level in the industry, providing an economical and efficient anode electrocatalyst for anion exchange membrane coupled hydrogen production technology.

[0030] (4) The catalyst material prepared by the present application has simple preparation method, low cost, excellent performance, high efficiency and stable catalysis of glycol electro-oxidation, and has potential for large-scale industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 X-ray diffraction pattern of the initial NiFe-sc-PBA material prepared in Example 1.

[0032] Figure 2 Scanning electron micrograph of the initial NiFe-sc-PBA material prepared in Example 1.

[0033] Figure 3 Transmission microscope image of the initial NiFe-sc-PBA material prepared for Example 1.

[0034] Figure 4 Linear sweep voltammetry comparison curves of the materials of Example 1 and Comparative Examples 1 and 2 in a three-electrode test system, wherein Example 1 is the NiFe-sc-PBA material, Comparative Example 1 is the NiFe-sc-PBA material, and Comparative Example 2 is the NiO material.

[0035] Figure 5 Faradic efficiency column chart of the NiFe-sc-PBA material prepared for Example 1.

[0036] Figure 6 In-situ Raman test curve of the NiFe-sc-PBA material prepared for Example 1.

[0037] Figure 7 Quasi-in-situ electrochemical impedance spectroscopy test curve of the NiFe-sc-PBA material prepared for Example 1.

[0038] Figure 8 Current density-voltage curve of the NiFe-sc-PBA material prepared for Example 1 as an anode catalyst in an anion exchange membrane coupled hydrogen production device.

[0039] Figure 9 Faradic efficiency column chart of the NiFe-sc-PBA material prepared for Example 1 as an anode catalyst in an anion exchange membrane coupled hydrogen production device under different current densities.

[0040] Figure 10 Constant current curve diagram of the NiFe-sc-PBA material prepared for Example 1 as an anode catalyst in an anion exchange membrane coupled hydrogen production device under 1.0 A·cm -2 and 1.5 A·cm -2 current densities. DETAILED DESCRIPTION

[0041] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without any creative effort belong to the scope of protection of the present application.

[0042] "Ranges" disclosed herein are in the form of a lower limit and an upper limit. There can be one or more lower limits, and one or more upper limits. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges that can be defined in this manner are inclusive and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, where ranges of 100-140 and 500-900 are listed for a particular parameter, it is understood that ranges of 100-140 and 500-900 are contemplated. In addition, if a minimum range value of 1 and 2 are listed, and if a maximum range value of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-2, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0043] In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing all the individual real combinations between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all the real numbers between "0-5" have been listed herein, and "0-5" is just a shorthand way of describing these numerical combinations.

[0044] In the present application, unless otherwise stated, all the embodiments and preferred embodiments mentioned herein can be combined with each other to form new technical solutions.

[0045] Example 1 Preparation of Prussian Blue Analogues (MOFs) Ethylene Glycol Electro-oxidation Catalyst with Low Valence Active Sites

[0046] (1) Cut the nickel foam into the appropriate size (4 cm x 4.5 cm), and ultrasonic in acetone, ethanol and 3 mol / L hydrochloric acid for 15 minutes, and then continue to use multiple ethanol ultrasonic treatment for 15 minutes until the last ultrasonic treatment of ethanol solution is colorless and transparent, no nickel ion residue;

[0047] (2) Weigh a certain amount of nickel chloride hexahydrate, sodium citrate and polyvinylpyrrolidone into deionized water, stir for 10 minutes to a transparent colorless solution. Among them, the molar ratio of nickel chloride and sodium citrate is 3:5, and the average weight average molecular weight of polyvinylpyrrolidone is 58000;

[0048] (3) Weigh a certain amount of potassium ferricyanide into deionized water (the molar ratio of nickel chloride and potassium ferricyanide is 3:1), stir for 10 minutes to a transparent colorless solution;

[0049] (4) Under vigorous stirring, the solution in step (2) is added dropwise into the solution in step (3) using a dropper.

[0050] (5) The solution obtained in step (4) is transferred to a 100 mL Teflon-lined inner liner, and a piece of clean nickel foam obtained in step (1) is placed in it.

[0051] (6) Put the Teflon inner city of step (5) into a suitable steel sleeve, and put it into an 80°C oven for hydrothermal reaction for 27 hours.

[0052] (7) After the steel sleeve of step (6) is naturally cooled, the foamed nickel is taken out and rinsed with deionized water and ethanol for 3 times respectively, and then placed in a 60°C vacuum oven overnight for drying to obtain the NiFe-sc-PBA catalyst.

[0053] Comparative Example 1

[0054] The operation steps of Example 1 are repeated, except that the electrolyte during the test is a solution with the same alkali content but without ethylene glycol.

[0055] Comparative Example 2

[0056] The foamed nickel treated in step (1) of Example 1 is directly annealed in a muffle furnace at 250°C for 2 hours to obtain a self-supported NiO electrode.

[0057] II. Performance characterization test

[0058] 1. X-ray diffraction and scanning electron microscopy

[0059] Figure 1 X-ray diffraction pattern of the ethylene glycol electro-oxidation catalyst NiFe-sc-PBA with low-valence active center prepared in Example 1. It can be seen from the figure that the chemical structure of NiFe-sc-PBA is K2Ni[Fe(CN)6], and the three highest intensity peaks in the standard spectrum are attributed to the foamed nickel substrate. Figure 1

[0060] Figure 2 Scanning electron micrograph of the ethylene glycol electro-oxidation catalyst NiFe-sc-PBA with low-valence active center prepared in Example 1. It can be seen from the figure that the catalyst presents a certain size distribution of regular hexagonal morphology. Figure 2

[0061] Figure 3 Transmission microscope image of the ethylene glycol electro-oxidation catalyst NiFe-sc-PBA with low-valence active center prepared in Example 1. It can be seen from the figure that the observed d spacing of 0.249 nm corresponds to the (400) K2Ni[Fe(CN)6] crystal face. Figure 3

[0062] III. Effect comparison

[0063] 3.1 Comparison of electrochemical performance

[0064] ​​​In Example 1, all electrochemical ethylene glycol oxidation performance tests of NiFe-sc-PBA catalysts were performed in a three-electrode system with Pt mesh as the counter electrode, Hg / HgO as the reference electrode, and the grown NiFe-sc-PBA material self-supported on the nickel foam as the working electrode. The nickel foam was cut into an effective working area of 1 cm x 1 cm or 1 cm x 0.5 cm, and then clamped on a platinum electrode clamp, ensuring that the immersed part below the page area is the effective working area. The electrochemical workstation uses Chenhua CHI 760E and Aiview XP20, and the electrolyte solution is 3M KOH containing 1M ethylene glycol, and the electrochemical test is carried out at room temperature and atmospheric pressure.

[0065] In Comparative Example 1, the electrode preparation is the same as Example 1, but the electrolyte does not contain ethylene glycol.

[0066] In Comparative Example 2, a NiO electrode is used as the working electrode.

[0067] Figure 4 The linear sweep voltammetry comparison curves of the NiFe-sc-PBA and NiO materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 in different electrolytes. From Figure 4 It can be seen that the potential of Example 1 is 1.48V and 1.62V at 500mA·cm -2 and 1000mA·cm -2 , which is significantly better than Comparative Examples 1 and 2.

[0068] Figure 5 The Faraday efficiency column chart of the NiFe-sc-PBA material prepared in Example 1 at different potentials in the three-electrode test system. From Figure 5 It can be seen that the formic acid Faraday efficiency of Example 1 is very high in a wide potential range (1.45V to 1.70V), >94.5%, and reaches the highest formic acid Faraday efficiency of 98.6% at 1.45V.

[0069] Figure 6 The in-situ Raman test curve of the NiFe-sc-PBA material prepared in Example 1 under different conditions. From Figure 6 It can be seen that in the EGOR process of the NiFe-sc-PBA material prepared in Example 1, the peak belonging to the cyano group always maintains a certain intensity, and there is no peak belonging to Ni -1 in the range of 500 to 600cm 3+ , indicating that the original structure of the catalyst remains unchanged in the EGOR process, and low-valence nickel serves as the catalytically active site.

[0070] Figure 7The images show quasi-in-situ electrochemical impedance spectroscopy (EIS) curves of the NiFe-sc-PBA material prepared in Example 1 under different conditions. Figure 7 As can be seen, the NiFe-sc-PBA material prepared in Example 1 maintains a certain intensity at the peak shoulder position in the high-frequency region during the EGOR process, and does not disappear as the potential increases. This indicates that the catalyst is not oxidized to a higher valence state during the EGOR process, and low-valence nickel is used as the catalytic active site.

[0071] 3.2 Comparison of Electrolytic Catalytic Performance

[0072] The electrocatalytic performance of NiFe-sc-PBA was tested using an anion exchange membrane coupled hydrogen production electrolyzer system. A self-supporting NiFe-sc-PBA catalyst was used as the anode catalyst, and commercially available 40% Pt / C black was used as the cathode catalyst. 10 mg of commercial 40% Pt / C powder catalyst was weighed and added to a mixture of 80 μL and 5 wt% Pt / C black catalyst. A cathode catalyst slurry was prepared in an ethanol solution and ultrasonicated in a low-temperature water bath for at least 30 minutes to obtain a homogeneous catalyst slurry. The cathode catalyst slurry was then sprayed onto hydrophilic carbon paper, with a cathode Pt / C catalyst loading of 1.0 mg·cm³. -2 Finally, a self-supported NiFe-sc-PBA catalyst, a sustainability X37-50 G60 anion exchange membrane, and a cathode carbon paper were loaded and tested in a coupled hydrogen production electrolyzer. The anode electrolyte solution was 1M KOH containing 1M ethylene glycol, and the cathode electrolyte solution was 1M KOH. The test temperature was room temperature, and the flow rate was 30 mL / min. -1 .

[0073] Figure 8 The current density-voltage curves of the NiFe-sc-PBA material prepared in Example 1 as the anode catalyst in an anion exchange membrane coupled hydrogen production device and a comparative example 1 anion exchange membrane water electrolysis device are shown. Figure 8 As can be seen, the assembled coupled hydrogen production electrolyzer reaches 1.0 A·cm⁻¹. -2 and 1.5A·cm -2 The required voltage at the current density is as low as 2.02V and 2.15V, indicating that the NiFe-sc-PBA material has high catalytic activity at high current densities in anion exchange membrane coupled hydrogen electrolyzers.

[0074] Figure 9 The graph shows the Faradaic efficiency and formic acid yield of the NiFe-sc-PBA material prepared in Example 1 as an anode catalyst in an anion exchange membrane coupled hydrogen production device under different current densities. Figure 9 It can be seen that the assembled coupled hydrogen production electrolyzer operates at 200 to 1800 mA·cm⁻¹ -2It exhibits extremely high formic acid Faraday efficiency (>92%) at all current densities.

[0075] Figure 10 The figures show the galvanostatic curves of the NiFe-sc-PBA material prepared in Example 1 as an anode catalyst in an anion exchange membrane coupled hydrogen production device at different current densities. Figure 10 It can be seen that the assembled coupled hydrogen production electrolyzer operates at 1.5 A·cm⁻¹. -2 and 1.0A·cm -2 The catalyst showed no significant degradation after 500 hours of continuous operation at the current density, indicating its significant potential in practical applications of anion exchange membrane coupled hydrogen production.

[0076] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for preparing an ethylene glycol electrooxidation catalyst based on MOFs with low-valence active centers, characterized in that, Includes the following steps: (1) Cut the nickel foam into appropriate sizes and sonicate it in acetone, ethanol and hydrochloric acid of a certain concentration in sequence. Then continue to sonicate it with ethanol multiple times until the ethanol solution after sonication is colorless and transparent with no nickel ion residue. (2) Weigh out a certain amount of nickel chloride hexahydrate, sodium citrate and polyvinylpyrrolidone and dissolve them in deionized water, and stir until a transparent and colorless solution is obtained. (3) Weigh a certain amount of potassium ferricyanide and dissolve it in deionized water, stirring until a transparent and colorless solution is obtained; (4) While stirring vigorously, add the solution from step (2) dropwise into the solution from step (3); (5) Transfer the solution obtained in step (4) into an inert material liner, and place a piece of clean nickel foam obtained in step (1) into it; (6) Place the liner from step (5) in a suitable steel sleeve and place it in an 80°C oven for hydrothermal reaction for 27 hours. After the steel sleeve cools naturally, remove the nickel foam and rinse it several times with deionized water and ethanol respectively. Then place it in a 60°C vacuum oven to dry overnight to obtain the ethylene glycol electro-oxidation catalyst NiFe-sc-PBA.

2. The preparation method according to claim 1, characterized in that: in, In step (1), the hydrochloric acid concentration was 3 mol / L, and the ultrasonic treatment time was 15 min; the cut shape of the nickel foam was approximately square. The ratio between the area of ​​the cut nickel foam and the volume of the inert material lining is 16–20 cm². 2 100mL.

3. The preparation method according to claim 1, characterized in that: in, In step (2), the molar ratio of nickel chloride to sodium citrate is 3:5, and the average weight-average molecular weight of polyvinylpyrrolidone is 58,000. In steps (2) and (3), the molar ratio of nickel chloride to potassium ferricyanide is 3:1, and the stirring time of the solution is 10 min.

4. The preparation method according to claim 1, characterized in that: in, In step (5), the inert material liner is selected from Teflon liners.

5. An ethylene glycol electrooxidation catalyst based on MOFs with low-valence active centers, characterized in that, It is prepared by the method described in any one of claims 1 to 4.

6. The ethylene glycol electrooxidation catalyst according to claim 5, characterized in that, The catalyst has a hexahedral morphology and does not undergo reconstruction during the electro-oxidation of ethylene glycol.

7. The application of the ethylene glycol electro-oxidation catalyst according to claim 5 or 6 in the preparation of an electrolytic oxygen electrode.

8. An electrolytic oxygen anode electrode, characterized in that, It includes an anode support and a catalyst material supported thereon, wherein the catalyst material is an ethylene glycol electro-oxidation catalyst prepared by the method described in any one of claims 1 to 4.

9. A method for electrolyzing water, characterized in that: The electrolytic oxygen anode electrode as described in claim 7 is used as the anode.

10. The method for electrolyzing water according to claim 9, characterized in that: in, The anolyte solution is a 1M KOH solution containing 1M ethylene glycol, and the cathode electrolyte solution is a 1M KOH solution.

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