Preparation method and application of crystalline-state and amorphous-state coupled electro-catalysis electrode

Abstract

The invention discloses a preparation method and application of a crystalline state and amorphous state coupled electro-catalysis electrode, and the preparation method comprises the following steps: dissolving nickel nitrate hexahydrate in water, dissolving ferrocenecarboxylic acid and terephthalic acid in N, N-2-methylformamide, mixing the two solutions, adding foamed nickel for solvothermal reaction, cleaning and drying to obtain an intermediate product; and carrying out electro-deposition on the intermediate product in an aqueous solution of nickel sulfate hexahydrate, cleaning and drying to obtain the crystalline state and amorphous state coupled electro-catalysis electrode. The crystalline-state and amorphous-state coupled electro-catalysis electrode disclosed by the invention has excellent electro-catalysis water / seawater decomposition activity and long-time working stability in a 1mol / L KOH solution and alkaline seawater.

Description

Technical Field

[0001] The present invention relates to the technical field of clean energy, and particularly relates to a preparation method and application of an electrocatalytic electrode with a coupled crystalline and amorphous state. Background Art

[0002] With the continuous increase in energy demand in the industrial society and the intensification of environmental pressure, the development of clean energy conversion and storage technologies has become particularly urgent. Electro-catalytic water splitting is regarded as a promising approach to solve the energy crisis due to its high theoretical energy conversion efficiency. Although most current electrolytic water research is carried out in a fresh water environment, considering the scarcity of fresh water resources, using seawater as the electrolysis medium is more ideal. Therefore, developing electrocatalysts suitable for fresh water and seawater environments has important practical application value. Although noble metal-based materials are ideal catalysts for electrolytic water and seawater decomposition, their natural scarcity, high cost, and instability in seawater limit their wide application. Therefore, developing low-cost, highly active, and corrosion-resistant water / seawater decomposition electrocatalysts to replace noble metal-based materials has become an urgent task.

[0003] Two-dimensional metal-organic frameworks (MOFs) have become potential catalyst materials in water electrolysis due to their high specific surface area, pore structure, and good electrical conductivity. However, MOFs exhibit poor electrochemical performance when directly used as OER and HER catalysts.

[0004] It is reported that there are mainly two ways to improve the catalytic efficiency of catalysts. First, through the design of heterostructure engineering, the redistribution of interfacial charges, the acceleration of electron transfer speed, and the optimization of the chemisorption states of reactants and intermediates can be achieved, thereby enhancing the intrinsic activity of the catalyst. Currently, most heterostructures are composed of two crystalline materials. Different from crystalline materials, amorphous materials have a large number of "dangling bonds" and unsaturated coordination sites due to their long-range disorder and short-range order characteristics, which not only increases the number of active sites but also provides more space for electrocatalytic reactions. In addition, due to the plasticity of their structure, amorphous materials exhibit excellent self-regulating ability in electrocatalytic reactions, thus bringing better stability.

[0005] Therefore, it is predictably believed that reasonably constructing a crystalline-amorphous (c-a) heterostructure can not only utilize the high electron conductivity of crystalline materials and the abundant active sites in the amorphous phase but also cause the redistribution of the electronic configuration of interfacial sites, further enhancing the electrocatalytic performance. Summary of the Invention

[0006] In view of this, the present invention provides a preparation method and application of an electrocatalytic electrode with a coupled crystalline and amorphous state.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A preparation method of an electrocatalytic electrode with coupled crystalline and amorphous states, comprising the following steps:

[0009] a. Cut the nickel foam into slices, ultrasonically clean them with dilute hydrochloric acid solution, ethanol and deionized water to remove the surface oxide layer and organic residues respectively, and dry them in a vacuum drying oven;

[0010] b. Take nickel nitrate hexahydrate, add it to deionized water, and magnetically stir at room temperature to obtain a light green homogeneous solution;

[0011] c. Take terephthalic acid and ferrocene formic acid, add them to N,N-dimethylformamide, and magnetically stir at room temperature to obtain a light yellow homogeneous solution;

[0012] d. Mix the solutions obtained in steps b and c, and magnetically stir to obtain a mixed solution;

[0013] e. Take four pieces of cleaned nickel foam and vertically fix them at the bottom of a polytetrafluoroethylene-lined reaction kettle. Slowly pour the mixed solution obtained in step d into the reaction kettle, keep it warm in an oven, then wash the product with ethanol and deionized water multiple times, and finally dry it in a vacuum drying oven to obtain the FcNi-BDC precursor;

[0014] f. Use an aqueous solution of nickel sulfate hexahydrate as the electrolyte, use the FcNi-BDC precursor obtained in step e as the working electrode, Hg / HgO as the reference electrode, and a graphite rod as the counter electrode. Set the current density and operate at room temperature to obtain the FcNi-BDC-aNiOOH composite electrode with coupled crystalline and amorphous states.

[0015] Preferably, in step a, the nickel foam is cut into pieces with a size of (1-2)×(2-4) cm, the concentration of the dilute hydrochloric acid solution is 1-4 mol / L, the ultrasonic cleaning time is 15-30 min, and it is dried in a vacuum oven at 60-80 °C for 6-12 h.

[0016] More preferably, the concentration of the dilute hydrochloric acid solution is 1 mol / L.

[0017] More preferably, the ultrasonic cleaning time is 15 min.

[0018] Preferably, in step b, the mass of nickel nitrate hexahydrate is 0.5816 g, the volume of deionized water is 20 mL, and the magnetic stirring time at room temperature is 20-60 min.

[0019] Preferably, in step c, the mass of terephthalic acid is 0.3356 g, the mass of ferrocene formic acid is 0.1423 g, the volume of N,N-dimethylformamide is 40 mL, and the magnetic stirring time at room temperature is 20-60 min.

[0020] Preferably, in step d, the magnetic stirring time is 5 - 30 min.

[0021] Preferably, in step e, the volume of the polytetrafluoroethylene-lined reactor is 100 mL, and it is kept warm at 100 - 150 °C for 6 - 16 h in an oven and dried at 60 - 80 °C for 6 - 12 h in a vacuum drying oven.

[0022] More preferably, it is kept warm at 125 °C for 12 h in an oven.

[0023] Preferably, in step f, the concentration of the nickel sulfate hexahydrate aqueous solution is 80 mmol / L, the current density is set to (-100) - (-10) mA / cm 2 , and the running time at room temperature is 300 - 1800 s.

[0024] Preferably, the molar ratio of terephthalic acid to ferrocene carboxylic acid is 10:3.

[0025] The composite material prepared by the preparation method of a crystalline and amorphous coupled electrocatalytic electrode, FcNi-BDC-aNiOOH, is a two-dimensional nanosheet array structure.

[0026] Application of the crystalline and amorphous coupled FcNi-BDC-aNiOOH composite electrode in electrocatalytic water / seawater decomposition.

[0027] The present invention has achieved the following technical effects compared with the prior art:

[0028] (1) The self-supporting crystalline and amorphous coupled catalytic electrode prepared by the preparation method of the present invention not only inherits the excellent physical and chemical properties of the FcNi-BDC precursor, but also generates a rich crystalline and amorphous heterointerface after electrodeposition composite, which is crucial for enhancing the electrocatalytic water decomposition activity;

[0029] (2) The firm interfacial contact between the amorphous layer and the FcNi-BDC precursor in the composite material prepared by the preparation method of the present invention enables them to have better interfacial coupling, further improving the ion and electron transport, not only increasing the active site density, but also achieving excellent stability for long-term operation;

[0030] (3) The preparation method of the present invention is simple and feasible. Brief Description of the Drawings

[0031] Figure 1 Scanning electron microscope photos of the products prepared in Examples 1 - 3 of the present invention;

[0032] Among them, Figure a is the product (FcNi-BDC) prepared in Example 1; Figure b is the product (aNiOOH) prepared in Example 2; Figure c is the product (FcNi-BDC-aNiOOH) prepared in Example 3;

[0033] Figure 2 is the X-ray diffraction pattern of the products prepared in Examples 1 to 3 of the present invention;

[0034] Figure 3 is the Raman spectrum of the products prepared in Examples 1 to 3 of the present invention;

[0035] Figure 4 is the linear voltammogram of the oxygen evolution reaction of the products prepared in Examples 1 to 3 of the present invention and RuO 2 in 1 mol / L KOH solution;

[0036] Figure 5 is the linear voltammogram of the oxygen evolution reaction of the products prepared in Examples 1 to 3 of the present invention and RuO 2 in 1 mol / L KOH solution;

[0037] Figure 6 is the linear voltammogram of the hydrogen evolution reaction of the products prepared in Examples 1 to 3 of the present invention and Pt / C in 1 mol / L KOH solution;

[0038] Figure 7 is the Tafel curve of the hydrogen evolution reaction of the products prepared in Examples 1 to 3 of the present invention and Pt / C in 1 mol / L KOH solution.

[0039] Figure 8 is the chronoamperometric stability test chart of the oxygen evolution reaction and hydrogen evolution reaction of the product prepared in Example 3 of the present invention in 1 mol / L KOH solution;

[0040] Figure 9 is the linear voltammogram of the oxygen evolution reaction of the product prepared in Example 3 of the present invention in seawater solution;

[0041] Figure 10 is the linear voltammogram of the electrocatalytic water splitting of the product prepared in Example 3 of the present invention and Pt / C||RuO 2 in 1 mol / L KOH and seawater solution. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] The present invention discloses a preparation method of an electrocatalytic electrode with the coupling of crystalline and amorphous states, comprising the following steps:

[0044] a. Cut the nickel foam into pieces of (1 - 2)×(2 - 4) cm in size, ultrasonically clean it with 1 - 4 mol / L dilute hydrochloric acid solution, ethanol and deionized water for 15 - 30 min to remove the surface oxide layer and organic residues respectively. After cleaning with deionized water, dry it in a vacuum drying oven at 60 - 80 °C for 6 - 12 h;

[0045] b. Take 0.5816 g of nickel nitrate hexahydrate, add it to 20 ml of deionized water, and magnetically stir it at room temperature for 20 - 60 min to obtain a light green homogeneous solution;

[0046] c. Take 0.3356 g of terephthalic acid and 0.1423 g of ferrocene carboxylic acid, add them to 40 mL of N,N - dimethylformamide, and magnetically stir it at room temperature for 20 - 60 min to obtain a light yellow homogeneous solution;

[0047] d. Mix the solutions obtained in steps b and c, and magnetically stir for 5 - 30 min to obtain a mixed solution;

[0048] e. Take four pieces of cleaned nickel foam and vertically fix them at the bottom of a 100 mL polytetrafluoroethylene - lined reaction kettle. Slowly pour the mixed solution obtained in step d into the reaction kettle, keep it warm in an oven at 100 - 150 °C for 6 - 16 h, then wash the product with ethanol and deionized water multiple times, and finally dry it in a vacuum drying oven at 60 - 80 °C for 6 - 12 h to obtain the FcNi - BDC precursor;

[0049] f. Use an 80 mmol / L aqueous solution of nickel sulfate hexahydrate as the electrolyte, the FcNi - BDC precursor obtained in step e as the working electrode, Hg / HgO as the reference electrode, and a graphite rod as the counter electrode. Set the current density to (-100) - (-10) mA / cm 2 , and operate it at room temperature for 300 - 1800 s to obtain the FcNi - BDC - aNiOOH composite electrode with the coupling of crystalline and amorphous states.

[0050] The present invention also discloses a composite material prepared by a method for preparing an electrocatalytic electrode with coupled crystalline and amorphous states. FcNi-BDC-aNiOOH has a two-dimensional nanosheet array structure.

[0051] The present invention also discloses the application of the FcNi-BDC-aNiOOH composite electrode with coupled crystalline and amorphous states in electrocatalytic water / seawater decomposition.

[0052] In the present invention, unless otherwise specified, all raw materials for preparation are commercially available products well-known to those skilled in the art.

[0053] In the present invention, nickel nitrate hexahydrate is preferably Ni(NO 3 ) 2 ·6H 2 O.

[0054] In the present invention, terephthalic acid is preferably C 8 H 6 O 4 .

[0055] In the present invention, ferrocene carboxylic acid is preferably C 11 H 10 FeO 2 .

[0056] In the present invention, the reagent dissolution and mixing method is magnetic stirring at room temperature. The present invention has no special limitation on the dissolution and mixing process, and it can be carried out by a process well-known to those skilled in the art.

[0057] In the present invention, the dissolution process is preferably to place nickel nitrate hexahydrate in deionized water, add a magnetic stir bar, and stir at 500 - 1000 rpm on a magnetic stirrer for 20 - 60 min for dissolution.

[0058] In the present invention, the synthesis method of the FcNi-BDC precursor is a solvothermal reaction. The present invention has no special limitation on the solvothermal reaction, and it can be carried out by a process well-known to those skilled in the art. In the present invention, the solvothermal reaction is preferably to place the reaction kettle in an oven at 100 - 150 °C for heat preservation for 6 - 16 h, and the heating rate is 2 - 8 °C / min.

[0059] After the solvothermal reaction is completed, the FcNi-BDC precursor is successively washed and dried in the present invention.

[0060] In the present invention, the cleaning agent used for cleaning is preferably 99.8% anhydrous ethanol and deionized water.

[0061] In the present invention, the drying method is preferably vacuum drying; the temperature for vacuum drying is preferably 50 - 100 °C, more preferably 50 - 90 °C, and most preferably 60 - 80 °C; the time is preferably 3 - 12 h, more preferably 5 - 10 h, and most preferably 6 - 8 h.

[0062] In the present invention, the electrodeposition is preferably carried out in a three - electrode system, where FcNi - BDC is the working electrode, Hg / HgO is the reference electrode, and a graphite rod is the counter electrode in the three - electrode system. In the present invention, the current density of the electrodeposition is preferably (-100) - (-10) mA / cm 2 , more preferably (-80) - (-30) mA / cm 2 , most preferably (-60) - (-40) mA / cm 2 . The time is preferably 300 - 1800 s, more preferably 600 - 1200 s, and most preferably 800 - 1000 s.

[0063] In the present invention, the electrodeposition is preferably carried out using a Shanghai Chenhua CHE760e electrochemical workstation.

[0064] Example 1:

[0065] Preparation of FcNi - BDC:

[0066] a. Cut the nickel foam into pieces of 1×2 cm size, and ultrasonically clean it with 1 mol / L dilute hydrochloric acid solution, ethanol, and deionized water for 15 min to remove the surface oxide layer and organic residues respectively. After cleaning with deionized water, dry it in a vacuum drying oven at 60 °C for 6 h;

[0067] b. Take 0.5816 g of nickel nitrate hexahydrate, add it to 20 mL of deionized water, and magnetically stir it at room temperature for 20 min to obtain a light green homogeneous solution;

[0068] c. Take 0.3356 g of terephthalic acid and 0.1423 g of ferrocene carboxylic acid, add them to 40 mL of N,N - dimethylformamide, and magnetically stir it at room temperature for 20 min to obtain a light yellow homogeneous solution;

[0069] d. Mix the solutions obtained in steps b and c, and magnetically stir for 5 min to obtain a mixed solution;

[0070] e. Vertically fix four pieces of cleaned nickel foam at the bottom of a 100 mL polytetrafluoroethylene - lined reaction kettle, slowly pour the mixed solution obtained in step d into the reaction kettle, keep it warm at 125 °C in an oven for 12 h, then wash the product with ethanol and deionized water multiple times, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain FcNi - BDC.

[0071] Among them, Figure 1a is the SEM image of FcNi-BDC. It can be seen from Figure 1 a that the morphology of FcNi-BDC is square flakes with a nanosheet array on the surface; the side length of the square flakes is about 5 μm;

[0072] Figure 2 is the XRD pattern of FcNi-BDC (the first curve from bottom to top). It can be seen from Figure 2 that the characteristic peaks of Ni-BDC (CCDC No. 985792) and Ni (04-0850) are contained in FcNi-BDC, which confirms the successful preparation of FcNi-BDC.

[0073] Figure 3 is the Raman pattern of FcNi-BDC (the first curve from bottom to top). It can be seen from Figure 3 that the bonds of O-Ni, C-H, C-O, C-C, and C═C are contained in FcNi-BDC, which further confirms the successful preparation of FcNi-BDC.

[0074] Example 2:

[0075] Preparation of aNiOOH:

[0076] a. Cut the nickel foam into pieces of 1×2 cm in size, and ultrasonically clean it with 1 mol / L dilute hydrochloric acid solution, ethanol, and deionized water for 15 min to remove the surface oxide layer and organic residues respectively; after cleaning with deionized water, dry it in a vacuum drying oven at 60 °C for 6 h;

[0077] b. Use an aqueous solution of nickel sulfate hexahydrate at 80 mmol / L as the electrolyte, the cleaned nickel foam as the working electrode, Hg / HgO as the reference electrode, and a graphite rod as the counter electrode. Set the current density to 100 mA / cm 2 , operate at room temperature for 900 s, then wash the product with deionized water multiple times, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain aNiOOH;

[0078] Among them, Figure 1 b is the SEM image of the aNiOOH. It can be seen from Figure 1 b that the morphology of aNiOOH is nanoflower-like;

[0079] Figure 2 is the XRD pattern of aNiOOH (the second curve from bottom to top). It can be seen from Figure 2 that only the characteristic peak of Ni (04-0850) is contained in aNiOOH, which confirms that aNiOOH is an amorphous structure.

[0080] Figure 3 is the Raman pattern of aNiOOH (the second curve from bottom to top). It can be seen from Figure 3It can be seen that aNiOOH contains the characteristic peaks of NiOOH, which confirms the successful preparation of aNiOOH.

[0081] Example 3:

[0082] Prepare FcNi-BDC-aNiOOH:

[0083] a. Cut the nickel foam into pieces of 1×2 cm, and ultrasonically clean it with 1 mol / L dilute hydrochloric acid solution, ethanol and deionized water for 15 min to remove the surface oxide layer and organic residues respectively; after washing with deionized water, dry it in a vacuum drying oven at 60 °C for 6 h;

[0084] b. Take 0.5816 g of nickel nitrate hexahydrate, add it to 20 mL of deionized water, and magnetically stir it at room temperature for 20 min to obtain a light green homogeneous solution;

[0085] c. Take 0.3356 g of terephthalic acid and 0.1423 g of ferrocene formic acid, add them to 40 mL of N,N-dimethylformamide, and magnetically stir it at room temperature for 20 min to obtain a light yellow homogeneous solution;

[0086] d. Mix the solutions obtained in steps b and c, and magnetically stir for 5 min to obtain a mixed solution;

[0087] e. Take four pieces of cleaned nickel foam and vertically fix them at the bottom of a 100 mL Teflon-lined reaction kettle. Slowly pour the mixed solution obtained in step d into the reaction kettle, keep it warm at 125 °C in an oven for 12 h, then wash the product with ethanol and deionized water multiple times, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain the FcNi-BDC precursor.

[0088] f. Use an 80 mmol / L aqueous solution of nickel sulfate hexahydrate as the electrolyte, the FcNi-BDC precursor obtained in step e as the working electrode, Hg / HgO as the reference electrode, and a graphite rod as the counter electrode. Set the current density to -100 mA / cm 2 , operate at room temperature for 900 s, then wash the product with deionized water multiple times, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain the FcNi-BDC-aNiOOH composite electrode with a coupled crystalline and amorphous state.

[0089] Among them, Figure 1 c is the SEM image of the FcNi-BDC-aNiOOH composite electrode with a coupled crystalline and amorphous state. It can be observed from Figure 1 c that the morphology of FcNi-BDC-aNiOOH is square sheet-like, with a nanosheet array on the surface; the side length of the square sheet is about 5 μm;

[0090] Figure 2XRD pattern of the FcNi-BDC-aNiOOH composite electrode with the coupling of crystalline and amorphous states (the third curve from bottom to top). It can be seen from Figure 2 that the characteristic peaks of Ni-BDC (CCDC No. 985792) and Ni (04-0850) are contained in FcNi-BDC-aNiOOH, which confirms the successful preparation of FcNi-BDC-aNiOOH;

[0091] Figure 3 Raman pattern of the FcNi-BDC-aNiOOH composite electrode with the coupling of crystalline and amorphous states (the third curve from bottom to top). It can be seen from Figure 3 that the characteristic peaks of FcNi-BDC and aNiOOH are contained in FcNi-BDC-aNiOOH, which confirms the successful preparation of FcNi-BDC-aNiOOH.

[0092] Test examples:

[0093] Using the self-supporting catalytic electrodes prepared in Examples 1 to 3 as the working electrode, 1 mol / L KOH solution (the solvent is deionized water) as the electrolyte, a graphite rod as the counter electrode, and Hg / HgO as the reference electrode to assemble a three-electrode system for three-electrode electrochemical performance testing:

[0094] Using the FcNi-BDC-aNiOOH composite electrode with the coupling of crystalline and amorphous states prepared in Example 3 as the working electrode, simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline seawater (1 M KOH + seawater) as the electrolytes, a carbon rod as the counter electrode, and Hg / HgO as the reference electrode to assemble a three-electrode system for three-electrode electrochemical performance testing;

[0095] Using the FcNi-BDC-aNiOOH composite electrode with the coupling of crystalline and amorphous states prepared in Example 3 as the anode and cathode, 1 mol / L KOH solution (the solvent is deionized water), simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline seawater (1 M KOH + seawater) as the electrolytes to assemble a two-electrode system for two-electrode electrochemical performance testing.

[0096] Performing electrochemical tests on the self-supporting one-dimensional nanorod array composite materials prepared in Examples 1 to 3 in natural seawater:

[0097] Among them, Figure 4 is the linear voltammogram of the products prepared in Examples 1 to 3 of the present invention and RuO 2 for the oxygen evolution reaction in 1 mol / L KOH solution. At a current density of 500 mA / cm 2 and 1000 mA / cm 2At this time, the overpotentials of Example 3 were 254 mV and 284 mV respectively, which were less than those of Example 1 (286 mV, 337 mV), Example 2 (309 mV, 352 mV) and RuO 2 The overpotential of. This confirmed that FcNi-BDC-aNiOOH has the best electrocatalytic oxygen evolution activity;

[0098] Figure 5 The products prepared in Examples 1 to 3 of the present invention and RuO 2 The Tafel curve graph of the oxygen evolution reaction in 1 mol / L KOH solution. The Tafel slope of Example 3 was 39.6 mV dec -1 , which was less than that of Example 1 (53.4 mV dec -1 ), Example 2 (48.2 mV dec -1 ) and RuO 2 (128.2 mV dec -1 ). This confirmed that FcNi-BDC-aNiOOH has good electrocatalytic oxygen evolution kinetics;

[0099] Figure 6 The linear voltammogram of the hydrogen evolution reaction of the products prepared in Examples 1 to 3 of the present invention and Pt / C in 1 mol / L KOH solution. When the current density was 10 mA / cm 2 , the overpotential of Example 3 was 77 mV, which was less than that of Example 2 (99 mV) and Example 1 (290 mV), and was close to the overpotential of Pt / C. This confirmed that FcNi-BDC-aNiOOH has good electrocatalytic hydrogen evolution activity;

[0100] Figure 7 The Tafel curve graph of the hydrogen evolution reaction of the products prepared in Examples 1 to 3 of the present invention and Pt / C in 1 mol / L KOH solution. The Tafel slope of Example 3 was 145.4 mV dec -1 , which was less than that of Example 1 (155.2 mV dec -1 ) and Example 1 (198.8 mV dec -1 ). This confirmed that FcNi-BDC-aNiOOH has good electrocatalytic hydrogen evolution kinetics;

[0101] Figure 8 The chronoamperometric stability test graph of the oxygen evolution reaction and hydrogen evolution reaction of the product prepared in Example 3 of the present invention in 1 mol / L KOH solution. In the oxygen evolution and hydrogen evolution reactions, Example 3 could work stably for at least 100 h and the current retention rates were 97.34% and 98.72% respectively. This confirmed that FcNi-BDC-aNiOOH has good stability in 1 mol / L KOH solution;

[0102] Figure 9 This is the linear voltammogram of the product prepared in Example 3 of the present invention for the oxygen evolution reaction in seawater solution. In 1 mol / L KOH solution, alkaline simulated seawater, and alkaline seawater, when the current density is 1000 mA / cm 2 , the overpotentials of Example 3 are 284 mV, 297 mV, and 329 mV respectively. This confirms that FcNi-BDC-aNiOOH also has good oxygen evolution reaction performance in seawater;

[0103] Figure 10 This is the linear voltammogram of the product prepared in Example 3 of the present invention and Pt / C||RuO 2 for electrocatalytic water splitting in 1 mol / L KOH and seawater solutions. In 1 mol / L KOH solution, when the current density is 10 mA / cm 2 and 100 mA / cm 2 , the voltages of FcNi-BDC-aNiOOH||FcNi-BDC-aNiOOH are 1.493 V and 1.706 V respectively, which are much smaller than those of Pt / C||RuO 2 (1.571 V, 1.821 V). In alkaline simulated seawater and alkaline seawater, the voltages at a current density of 10 mA / cm 2 are 1.515 V and 1.521 V respectively.

[0104] As mentioned above, it is only a preferred embodiment of the present invention, and it does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a crystalline and amorphous coupled electrocatalytic electrode, characterized in that: The following steps are involved: a. Slice the nickel foam, clean it with dilute hydrochloric acid solution, ethanol and deionized water ultrasonically to remove the surface oxide layer and organic residue respectively, and dry it in a vacuum drying oven; b. Take nickel nitrate hexahydrate, add it to deionized water, and stir it magnetically at room temperature to obtain a light green uniform solution; c. Take terephthalic acid and ferrocenecarboxylic acid, add them to N,N-2-methylformamide, and stir magnetically at room temperature to obtain a light yellow uniform solution; d. Mix the solutions obtained in steps b and c, and stir magnetically to obtain a mixed solution; e. Take four cleaned nickel foams and fix them vertically at the bottom of a polytetrafluoroethylene-lined reactor, slowly pour the mixed solution obtained in step d into the reactor, keep warm in an oven, then wash the product with ethanol and deionized water several times, and finally dry it in a vacuum drying oven to obtain a FcNi-BDC precursor; f. Using nickel sulfate hexahydrate aqueous solution as electrolyte, the FcNi-BDC precursor obtained in step e as working electrode, Hg / HgO as reference electrode, graphite rod as counter electrode, setting current density, and operating at room temperature to obtain a crystalline and amorphous coupled FcNi-BDC-aNiOOH composite electrode.

2. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 1, characterized in that: In the step a, the nickel foam is cut into a size of (1-2)×(2-4) cm, the concentration of the dilute hydrochloric acid solution is 1-4 mol / L, the ultrasonic cleaning time is 15-30 min, and the nickel foam is dried in a vacuum drying oven at 60-80° C. for 6-12 h.

3. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 1, characterized in that: In the step b, the mass of nickel nitrate hexahydrate is 0.5816 g, the volume of deionized water is 20 mL, and the magnetic stirring time at room temperature is 20 to 60 min.

4. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 1, characterized in that: In the step c, the mass of terephthalic acid is 0.3356 g, the mass of ferrocenecarboxylic acid is 0.1423 g, the volume of N,N-2-methylformamide is 40 mL, and the magnetic stirring time at room temperature is 20 to 60 min.

5. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 1, characterized in that: In the step d, the magnetic stirring time is 5-30 min.

6. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 1, characterized in that: In the step e, the volume of the polytetrafluoroethylene-lined reactor is 100 mL, and it is kept warm at 100-150° C. in an oven for 6-16 hours, and dried in a vacuum drying oven at 60-80° C. for 6-12 hours.

7. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 1, characterized in that: In step f, the concentration of the nickel sulfate hexahydrate aqueous solution is 80 mmol / L, and the current density is set to (-100) to (-10) mA / cm 2 , the running time at room temperature is 300 to 1800 seconds.

8. The method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to claim 4, characterized in that: The molar ratio of terephthalic acid to ferrocenecarboxylic acid is 10:

3.

9. The composite material prepared by the method for preparing a crystalline and amorphous coupled electrocatalytic electrode according to any one of claims 1 to 8, characterized in that: FcNi-BDC-aNiOOH is a two-dimensional nanosheet array structure.

10. Use of the crystalline and amorphous coupled FcNi-BDC-aNiOOH composite electrode according to claim 9 in electrocatalytic water / seawater decomposition.

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