A method for rapidly preparing bimetallic co-doped electrodes using a magnetic field and its application in photovoltaic coupled electrolysis of alkaline seawater

Abstract

The present invention discloses a method for rapidly preparing a bimetal co-doped electrode by using a magnetic field and its application in photovoltaic-coupled electrolysis of alkaline seawater, belonging to the technical field of photovoltaic-electrolysis seawater hydrogen production. An external magnetic field is applied to the iron foam immersed in a mixed solution containing NiSO4, Co(NO3)2 and Na2S2O3, and the bimetal co-doped electrode rapidly prepared by using the magnetic field is obtained after drying. The present invention provides a preparation method for rapidly preparing a bimetal co-doped electrode by using a magnetic field. At room temperature, by utilizing the ferromagnetic properties of the raw materials and the substrate, an external magnetic field is applied to promote the rapid formation of magnetic domains near the electrode-solution interface and the rearrangement of magnetic moments within the magnetic domains to promote the directional and rapid doping of metal ions within the interface, thereby rapidly preparing the electrode, improving the problems of high-temperature energy consumption and cumbersome steps in traditional synthesis methods, and the synthesis method is green and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic-seawater electrolysis hydrogen production, and in particular relates to a method for rapidly preparing a bimetallic co-doped electrode by utilizing a magnetic field and an application thereof in photovoltaic coupled electrolysis of alkaline seawater. Background Art

[0002] Energy crisis and environmental pollution are the biggest challenges facing mankind since the 21st century. The main form of hydrogen on the earth is in the form of water, so achieving efficient decomposition of water to produce hydrogen is the only choice for efficient production of hydrogen. However, due to the scarcity of fresh water resources compared to seawater resources, the abundance of seawater provides more practical utilization value for decomposing water to produce hydrogen. Since the Russian Rachenov proposed a unipolar water electrolysis hydrogen production device in 1888, electrochemical hydrogen production methods have been continuously studied. However, since it requires the input of an external electric field, it also produces a certain amount of energy loss. In the 20th century, Fujishima discovered that titanium dioxide can be used to decompose water to produce hydrogen under light conditions using photocatalytic means, namely the PC system. This method does not require an external electric field, greatly reducing energy loss, and has since opened up research on hydrogen production using light. However, due to the low hydrogen production efficiency of the PC system, photoelectrocatalysis (PEC) and photovoltaic electrocatalysis (PV-EC) systems have been proposed based on this. Among the three, the PV-EC system has the highest efficiency in decomposing seawater, and it has extremely high practical application value, so it has been widely studied.

[0003] The core of whether the performance of photovoltaic electrocatalytic system is superior or not lies in whether the performance of its core electrode is superior or not. Therefore, developing an electrode that can efficiently decompose seawater is of utmost importance. Existing methods for synthesizing electrodes include: solvothermal method, electric field assisted method, high temperature calcination method, chemical vapor deposition method, etc.

[0004] Since the solvothermal method, electric field assisted method, high temperature calcination method and chemical vapor deposition method have problems such as high temperature energy consumption and complicated steps, the use of high energy consumption methods is also not conducive to large-scale preparation of electrodes.

[0005] From the perspective of chemical reactions, since the oxygen evolution half reaction (OER) involves a four-electron transfer process, the kinetic process is slower than the hydrogen evolution reaction, and the overpotential is higher, making it the rate-determining step for the electrolysis of seawater. In addition, the presence of a large amount of chloride ions in seawater will cause a chlorine evolution reaction, which will compete with the oxygen evolution reaction, and thus be detrimental to the electrolysis of seawater. At the same time, the chloride produced during the electrolysis process will also corrode the electrode. In addition, there are a large number of calcium and magnesium ions in alkaline seawater, which will form hydroxide precipitation in an alkaline environment, thereby blocking the active sites of the electrode, resulting in problems such as low electrolysis efficiency.

[0006] Therefore, there is an urgent need in the art for an electrode that has a simple preparation method, low energy consumption, and can achieve efficient and stable decomposition of seawater. Summary of the invention

[0007] The purpose of the present invention is to provide a method for rapidly preparing a bimetallic co-doped electrode using a magnetic field and its application in photovoltaic coupled electrolysis of alkaline seawater, so as to solve the problems existing in the above-mentioned prior art.

[0008] One of the technical solutions provided by the present invention:

[0009] A method for rapidly preparing a bimetallic co-doped electrode by using a magnetic field, wherein an external magnetic field is applied to foamed iron immersed in a mixed solution containing NiSO4, Co(NO3)2 and Na2S2O3, and the bimetallic co-doped electrode is prepared after drying.

[0010] The principle of the present invention for preparing a bimetallic co-doped electrode by the above method is that under the action of an external magnetic field, magnetic domains at the material-solution interface are rapidly formed and some magnetic moments inside the magnetic domains undergo directional transformation, and the direction of the magnetic moments in the magnetic domains tends to be consistent with the direction of the external magnetic field. At this time, the transition metal ions (here specifically trivalent iron ions and divalent cobalt ions) at the phase interface are oriented under the magnetic interaction between their own ferromagnetism and the magnetic domains at the material-solution interface, thereby increasing the doping amount of metal ions and the directional doping of ions to improve the order of the material, thereby enhancing the OER activity.

[0011] Preferably, the molar concentration ratio of NiSO4, Co(NO3)2 and Na2S2O3 is (30-35):(30-35):1.

[0012] Preferably, the foamed iron is foamed iron with the oxide film removed.

[0013] The foam iron was cut into small pieces (1cm*2cm*2mm) with a thickness of 2mm, added into hydrochloric acid (1-3mol / L), ultrasonicated at 293.15K-298.15K for 15min, and then ultrasonically cleaned with ethanol and distilled water for 30s respectively to remove the oxide film and organic matter on the surface of the foam iron.

[0014] Preferably, the immersion time is 5 min 3 s, and the temperature is 293.15K-298.15K.

[0015] Preferably, the direction of the external magnetic field is perpendicular to the xoy plane of the foam iron and is the same as the positive direction of the Z axis.

[0016] Preferably, the strength of the external magnetic field is 11872-14840 Gs.

[0017] Preferably, the drying temperature is 333.15K and the drying time is 4-6h.

[0018] The second technical solution provided by the present invention is:

[0019] A bimetallic co-doped electrode prepared by the above preparation method.

[0020] The third technical solution provided by the present invention is:

[0021] An application of the above-mentioned bimetallic co-doped electrode quickly prepared by using a magnetic field in photovoltaic coupled electrolysis of alkaline seawater.

[0022] Beneficial effects of the present invention:

[0023] The bimetallic co-doped electrode prepared by the present invention is a nickel-cobalt co-doped oxyhydroxide electrode, which uses foamed iron with high natural abundance and ferromagnetism as a substrate and uses common transition metal salts as raw materials, thereby greatly reducing the cost of raw materials for synthesizing the electrode.

[0024] The present invention provides a method for rapidly preparing a bimetallic co-doped electrode using a magnetic field. At room temperature, the ferromagnetism of the raw materials and the substrate is utilized to apply an external magnetic field to promote the rapid formation of magnetic domains near the electrode-solution interface and the rearrangement of magnetic moments within the magnetic domains to promote the directional rapid doping of metal ions within the interface and thus rapidly prepare electrodes, thereby improving the problems of high temperature energy consumption and cumbersome steps of traditional synthesis methods. The synthesis method is green and efficient.

[0025] The present invention provides a bimetallic co-doped electrode, which improves the problem of slow kinetics of the rate-determining step in the water decomposition process through the high oxygen production activity of hydroxy oxide, and effectively solves the bottleneck of the water decomposition reaction.

[0026] The present invention provides a device for decomposing seawater using solar energy by coupling a bimetallic co-doped electrode with a photovoltaic panel, achieving a solar-to-hydrogen conversion efficiency (STH) of 14.6%, providing a typical demonstration and reference value for achieving hydrogen production by decomposing seawater at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1The low-magnification field emission scanning electron microscope images (low-magnification SEM) of the mS-Fe(Co, Ni)OOH electrode prepared in Example 1 and the S-Fe(Co, Ni)OOH electrode prepared in Comparative Example 1, wherein (a1) and (a2) are the low-magnification image and the high-magnification image of the mS-Fe(Co, Ni)OOH electrode, respectively, and (b1) and (b2) are the low-magnification image and the high-magnification image of the S-Fe(Co, Ni)OOH electrode;

[0029] Figure 2 High-magnification field emission scanning electron microscope images (high-magnification SEM) of the mS-Fe(Co, Ni)OOH electrode prepared in Example 1 and the S-Fe(Co, Ni)OOH electrode prepared in Comparative Example 1, wherein (a1) and (a2) are low-magnification and high-magnification images of the mS-Fe(Co, Ni)OOH electrode, respectively, and (b1) and (b2) are low-magnification and high-magnification images of the S-Fe(Co, Ni)OOH electrode, respectively;

[0030] Figure 3 X-ray diffraction (XRD) patterns of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the S-Fe(Co,Ni)OOH electrode prepared in Comparative Example 1;

[0031] Figure 4 It is a comparison diagram of the oxygen evolution reaction scanning linear voltammetry of the IF in Example 1 and the prepared mS-Fe(Co, Ni)OOH electrode and the S-Fe(Co, Ni)OOH electrode prepared in Comparative Example 1;

[0032] Figure 5 The graphs obtained by scanning linear voltammetry of oxygen evolution reaction of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the S-Fe(Co,Ni)OOH electrode prepared in Comparative Example 1 in simulated seawater and alkaline seawater;

[0033] Figure 6 The graph obtained by scanning linear voltammetry of total water decomposition in water, simulated seawater and alkaline seawater after coupling the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the S-Fe(Co,Ni)OOH electrode prepared in Comparative Example 1 with a photovoltaic panel and the power line of the photovoltaic panel;

[0034] Figure 7 Theoretical exchange current diagram of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the S-Fe(Co,Ni)OOH electrode prepared in Comparative Example 1 in water, simulated seawater and alkaline seawater after coupling with a photovoltaic panel;

[0035] Figure 8The graphs obtained by scanning linear voltammetry of oxygen evolution reaction of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the electrode prepared in Comparative Example 2;

[0036] Fig. 9 The graph obtained by scanning linear voltammetry of oxygen evolution reaction of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the electrode prepared in Comparative Example 3;

[0037] Fig.10 The graphs obtained by scanning linear voltammetry of oxygen evolution reaction of mS-Fe(Co,Ni)OOH electrodes prepared in Examples 1 and 2 and the electrode prepared in Comparative Example 4;

[0038] Fig.11 The graph obtained by scanning linear voltammetry of oxygen evolution reaction of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the electrode prepared in Comparative Example 5;

[0039] Fig.12 The graph obtained by scanning linear voltammetry of oxygen evolution reaction of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the electrode prepared in Comparative Example 6;

[0040] Fig.13 This is a graph obtained by scanning linear voltammetry of the oxygen evolution reaction of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the electrode prepared in Comparative Example 7. DETAILED DESCRIPTION

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0045] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0046] The room temperature described in the present invention refers to 293.15K-298.15K.

[0047] The simulated seawater in the embodiment of the present invention is prepared by mixing equal volumes of 0.5 mol / L NaCl aqueous solution and 1 mol / L KOH aqueous solution; the alkaline seawater is prepared by mixing equal volumes of natural seawater and 1 mol / L KOH aqueous solution; and the alkaline water is prepared by 1 mol / L KOH aqueous solution.

[0048] Other raw materials in the examples of the present invention are purchased from commercial sources.

[0049] Example 1 A method for rapidly preparing a bimetallic co-doped electrode using a magnetic field

[0050] S1. Cut the foam iron into small pieces (1cm*2cm*2mm) with a thickness of 2mm, add 20mL hydrochloric acid (3mol / L), ultrasonicate at 293.15K for 15min, and then ultrasonicate with ethanol and distilled water for 30s respectively to remove the oxide film and organic matter on the surface of the foam iron. This is named IF, and the cleaning method is recorded as B.

[0051] S2. Prepare 50mL of a mixed solution containing NiSO4·6H2O (0.087mol / L), Co(NO3)2·6H2O (0.087mol / L) and Na2S2O3·5H2O (0.0026mol / L), place the IF prepared in S1 in a 25mL beaker, apply an external magnetic field with a magnetic induction intensity of 14840Gs (denoted as S upwards) with a magnetic induction intensity perpendicular to the xoy plane of the foam iron and the same as the positive direction of the Z axis to the IF, and at the same time, take 5mL of the mixed solution and add it to the 25mL beaker. Under the action of the magnetic field, immerse it at 293.15K for 5min 3s, remove it and dry it in an oven (333.15K) for 4h to obtain the mS-Fe(Co,Ni)OOH electrode.

[0052] Example 2 A method for rapidly preparing a bimetallic co-doped electrode using a magnetic field

[0053] S1. Cut the foam iron into small pieces (1cm*2cm*2mm) with a thickness of 2mm, add 25mL hydrochloric acid (3mol / L), ultrasonicate at 295.15K for 15min, and then ultrasonicate with ethanol and distilled water for 30s respectively to remove the oxide film and organic matter on the surface of the foam iron. This is named IF, and the cleaning method is recorded as B.

[0054] S2. Prepare 50mL of a mixed solution containing NiSO4·6H2O (0.0832mol / L), Co(NO3)2·6H2O (0.0832mol / L) and Na2S2O3·5H2O (0.0026mol / L), place the IF prepared in S1 in a 25mL beaker, apply an external magnetic field (denoted as S upwards) with a magnetic induction intensity of 14840Gs and a direction perpendicular to the xoy plane of the foam iron and the same as the positive direction of the Z axis to the IF, and at the same time, take 5mL of the mixed solution and add it to the 25mL beaker. Under the action of the magnetic field, immerse it at 293.15K for 5min 3s, remove it and dry it in an oven (333.15K) for 5h to obtain the mS-Fe(Co,Ni)OOH electrode.

[0055] Example 3 A method for rapidly preparing a bimetallic co-doped electrode using a magnetic field

[0056] S1. Cut the foam iron into small pieces (1cm*2cm*2mm) with a thickness of 2mm, add 30mL hydrochloric acid (3mol / L), ultrasonicate at 298.15K for 15min, and then ultrasonicate with ethanol and distilled water for 30s respectively to remove the oxide film and organic matter on the surface of the foam iron, named IF, and the cleaning method is recorded as B;

[0057] S2. Prepare 50mL of a mixed solution containing NiSO4·6H2O (0.091mol / L), Co(NO3)2·6H2O (0.091mol / L) and Na2S2O3·5H2O (0.0026mol / L), place the IF prepared in S1 in a 25mL flask, apply an external magnetic field (denoted as S upwards) with a magnetic induction intensity of 11872Gs and a direction perpendicular to the xoy plane of the foam iron and the same as the positive direction of the Z axis to the IF, and at the same time, take 5mL of the mixed solution and add it to the 25mL beaker. Under the action of the magnetic field, immerse it at 298.15K for 5min 3s, remove it and dry it in an oven (333.15K) for 6h to obtain the mS-Fe(Co,Ni)OOH electrode.

[0058] Comparative Example 1

[0059] The same as Example 1, except that the external magnetic field is removed, and the synthesized electrode is recorded as S-Fe(Co,Ni)OOH electrode.

[0060] Comparative Example 2

[0061] S1. Cut the foam iron into small pieces as in Example 1, add 7 mL of acetone to rinse the foam iron, then add 30 mL of hydrochloric acid (0.5 mol / L), ultrasonicate for 5 min, and finally ultrasonicate with ethanol and distilled water for 30 s respectively. The size of the foam iron remains unchanged, and the oxide film and organic matter on the surface of the foam iron are removed. This cleaning method is recorded as A;

[0062] S2. Same as Example 1.

[0063] Comparative Example 3

[0064] The same as Example 1, except that in Comparative Example 3-1, the thickness of the foamed iron in Example 1 is replaced by 1 mm (i.e., 1 cm*2 cm*1 mm); in Comparative Example 3-2, the thickness of the foamed iron in Example 1 is replaced by 1.6 mm (i.e., 1 cm*2 cm*1.6 mm).

[0065] Comparative Example 4

[0066] The same as Example 1, except that in Comparative Example 4-1, the magnetic induction intensity in S2 is adjusted to 2968 Gs; in Comparative Example 4-2, the magnetic induction intensity in S2 is adjusted to 5936 Gs; in Comparative Example 4-3, the magnetic induction intensity in S2 is adjusted to 8904 Gss.

[0067] Comparative Example 5

[0068] The same as Example 1, except that the immersion time in Comparative Example 5-1 is 3 s; the immersion time in Comparative Example 5-2 is 3 min 3 s; the immersion time in Comparative Example 5-3 is 7 min 3 s; and the immersion time in Comparative Example 5-4 is 10 min 3 s.

[0069] Comparative Example 6

[0070] The same as Example 1, the only difference is that the direction of the magnetic induction intensity of the external magnetic field is changed to be perpendicular to the foam iron xoy plane and upward, that is, the direction of the magnetic flux lines is opposite to the positive direction of the Z axis (denoted as N upwards).

[0071] Comparative Example 7

[0072] Same as Example 1, except that the immersion temperature is replaced with 277.15K.

[0073] Performance test

[0074] 1. Use SEM to characterize the morphology experiment

[0075] The morphology of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the S-Fe(Co,Ni)OOH electrode prepared in Comparative Example 1 were characterized by SEM. Figure 1 Low magnification field emission scanning electron microscopy (SEM) and Figure 2 High magnification field emission scanning electron microscopy (SEM) Figure 1 As shown in the figure, under low magnification SEM, the morphology of the electrodes prepared in Example 1 and Comparative Example 1 are both 3D structures, and compared with the S-Fe(Co,Ni)OOH prepared in Comparative Example 1, the nanoparticles formed on the surface of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 are more dispersed and more ordered, increasing the electrochemical active area. Figure 2 As shown in the high-magnification SEM, in comparison, the nanoparticles formed by the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 have stronger three-dimensionality and thinner nanosheets, which increases its electrochemical active area.

[0076] 2. Determination of crystal phase and its composition

[0077] The crystal phase and composition of the mS-Fe(Co,Ni)OOH electrode prepared in Example 1 and the S-Fe(Co,Ni)OOH electrode prepared in Comparative Example 1 were determined by X-ray diffractometer. Figure 3 X-ray diffraction (XRD) patterns of mS-Fe(Co,Ni)OOH electrode and S-Fe(Co,Ni)OOH electrode.

[0078] like Figure 3As shown, the peak positions in the XRD spectra of the electrodes prepared in Example 1 and Comparative Example 1 are basically consistent, and the peaks in the spectra can be respectively attributed to α-FeOOH, Fe3O4, α-NiOOH and Fe(OH)3, confirming the existence of oxyhydroxide. Compared with the S-Fe(Co,Ni)OOH electrode, the peak intensity of mS-Fe(Co,Ni)OOH is generally higher, proving that the crystallinity of oxyhydroxide and ferrosoferric oxide can be improved under the action of an external magnetic field, and a higher crystallinity is more conducive to improving the OER activity of the electrode.

[0079] 3. Electrochemical test experiment

[0080] The IF electrode, mS-Fe(Co,Ni)OOH electrode and S-Fe(Co,Ni)OOH electrode prepared in Example 1 were tested at room temperature using a CHI760E electrochemical workstation. The test used a standard three-electrode system (except for the full water splitting test, which used a two-electrode system), where the IF electrode, mS-Fe(Co,Ni)OOH electrode and S-Fe(Co,Ni)OOH electrode were used as working electrodes, the platinum sheet was used as the counter electrode, and the Hg / HgO electrode was used as the reference electrode. Unless otherwise specified, the electrolyte was 1 mol / L KOH, and the scan rate of all linear sweep voltammetry (LSV) was 5 mV·s -1 , the voltages are relative to the reversible hydrogen electrode (RHE).

[0081] Figure 4 The linear sweep voltammetric curve of the above electrode under water oxidation potential. According to the test results, the mS-Fe(Co,Ni)OOH electrode has the best oxygen production activity: when the current density is 50mAcm -2 When the voltage is 1.75V, the overpotential of the mS-Fe(Co,Ni)OOH electrode is only 246mV, which is better than that of the S-Fe(Co,Ni)OOH electrode and the IF electrode (their oxygen evolution overpotentials are 267mV and 308mV respectively at the same current density). The saturation current density of the mS-Fe(Co,Ni)OOH electrode is also better than that of the S-Fe(Co,Ni)OOH electrode and the IF electrode. When the voltage is 1.75V, the saturation current density of the mS-Fe(Co,Ni)OOH electrode reaches 375mAcm -2 , while the S-Fe(Co,Ni)OOH electrode and IF electrode only reached 263mAcm -2 , 188.52mAcm -2 The results show that compared with IF and S-Fe(Co,Ni)OOH electrodes, mS-Fe(Co,Ni)OOH electrode has the best electrochemical performance.

[0082] 4. Water decomposition performance test in seawater

[0083] Figure 5 The linear sweep voltammetric curves of the mS-Fe(Co,Ni)OOH electrode of Example 1 and the S-Fe(Co,Ni)OOH electrode of Comparative Example 1 at oxidation potential in water, simulated seawater, and alkaline natural seawater. The measurement results show that the saturation current density of the mS-Fe(Co,Ni)OOH electrode in different electrolytes is higher than that of the S-Fe(Co,Ni)OOH electrode. Correspondingly, the saturation current density of the mS-Fe(Co,Ni)OOH electrode in simulated seawater and alkaline seawater at a voltage of 1.75V is 150.12mAcm -2 , 133.78mAcm -2 The saturation current density of S-Fe(Co,Ni)OOH electrode in simulated seawater and alkaline seawater at 1.75V is 105.2mAcm -2 , 95mAcm -2 .

[0084] 5. Photovoltaic-electrolysis seawater system test

[0085] The electrochemical workstation 760E was first connected to a monocrystalline silicon solar panel and then connected in series with two working electrodes, namely the mS-Fe(Co, Ni)OOH electrode of Example 1 and the S-Fe(Co, Ni)OOH electrode of Comparative Example 1, to form a photovoltaic-seawater electrolysis system. The electrochemical performance test results of the system are shown in FIG. Figure 6 The measurement results show that under the illumination conditions of standard simulated sunlight intensity (AM 1.5G, 100mW), when the electrolyte is alkaline water, the STH efficiency of the mS-Fe(Co,Ni)OOH electrode reaches 14.6% (the STH efficiency of the S-Fe(Co,Ni)OOH electrode is 13.6%), and when the electrolyte is alkaline seawater, its STH efficiency reaches 10.2% (the STH efficiency of the S-Fe(Co,Ni)OOH electrode is 9.5%). The STH efficiency of the mS-Fe(Co,Ni)OOH electrode exceeds 10%. At the same time, when the electrolyte is alkaline water, its theoretical exchange current density reaches 12.6mAcm -2 , when the electrolyte is alkaline seawater, it reaches 9.2mAcm -2 , which has certain application prospects.

[0086] 6. Photovoltaic-seawater electrolysis system test

[0087] The mS-Fe(Co,Ni)OOH electrode of Example 1 and the S-Fe(Co,Ni)OOH electrode of Comparative Example 1 were coupled to photovoltaic panels respectively, and then the theoretical exchange current diagrams of the two in simulated seawater and alkaline seawater were measured. The results are shown in Figure 7 ,from Figure 7 It can be seen that compared with S-Fe(Co,Ni)OOH, the theoretical exchange current density of mS-Fe(Co,Ni)OOH in alkaline water is higher.

[0088] 7. Determine the linear sweep voltammetric curves of the oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 2.

[0089] Figure 8 The scanning linear voltammetry graphs of the electrode materials obtained by different cleaning methods for the electrodes prepared in Example 1 and Comparative Example 2 are obtained by Figure 8 It can be seen that the OER performance of the electrode synthesized by foam iron cleaned by cleaning method B is better.

[0090] 8. Determine the linear sweep voltammetric curves of the oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 3.

[0091] Fig. 9 The graphs obtained by scanning linear voltammetry of oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 3 are as follows: Fig. 9 It can be seen that the OER performance of the electrode synthesized using foam iron with a thickness of 2 mm is better.

[0092] 9. Determine the linear sweep voltammetric curves of oxygen evolution reaction of the electrodes prepared in Example 1, Example 2 and Comparative Example 4.

[0093] Fig.10 The graphs obtained by scanning linear voltammetry of oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 4 are as follows: Fig.10 It can be seen that when the external magnetic field strength is 11842Gs-14840Gs, the OER performance of the synthesized electrode is better.

[0094] 10. Determine the linear sweep voltammetric curves of oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 5.

[0095] Fig.11 The oxygen evolution reaction scanning linear voltammetry diagram of the electrodes prepared in Example 1 and Comparative Example 5 is shown in FIG. Fig.11 It can be seen that the OER performance of the synthesized electrode is better when the immersion time is 5min3s.

[0096] 11. Determine the linear sweep voltammetric curves of oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 6.

[0097] Fig.12 The oxygen evolution reaction scanning linear voltammetry diagram of the electrodes prepared in Example 1 and Comparative Example 6 is shown in FIG. Fig.13 It can be seen that the OER performance of the synthesized electrode is better when the direction of the external magnetic field is S upwards.

[0098] 12. Determine the linear sweep voltammetric curves of oxygen evolution reaction of the electrodes prepared in Example 1 and Comparative Example 7.

[0099] Fig.13 The oxygen evolution reaction scanning linear voltammetry diagram of the electrodes prepared in Example 1 and Comparative Example 7 is shown in FIG. Fig.13 It can be seen that the OER performance of the electrode synthesized at room temperature is better.

[0100] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. Application of a bimetallic co-doped electrode in photovoltaic coupled electrolysis of alkaline seawater, characterized in that: The preparation method of the bimetallic co-doped electrode comprises the following steps: applying an external magnetic field to the foamed iron immersed in a mixed solution containing NiSO4, Co(NO3)2 and Na2S2O3, and drying to obtain the bimetallic co-doped electrode; The foamed iron is the foamed iron with the oxide film removed; The method for removing the oxide film of the foam iron is as follows: adding the foam iron to hydrochloric acid, ultrasonically cleaning at 293.15K for 15 minutes, and then ultrasonically cleaning with ethanol and distilled water for 30 seconds respectively; The specifications of the foam iron are 1cm*2cm*2mm; The immersion time is 5 min 3 s, and the temperature is 293.15 K; The direction of the external magnetic field is perpendicular to the xoy plane of the foam iron and is the same as the positive direction of the Z axis; The intensity of the external magnetic field is 14840Gs; The drying temperature is 333.15K and the drying time is 4-6h.

2. The use according to claim 1, characterized in that: The molar concentration ratio of NiSO4, Co(NO3)2 and Na2S2O3 is (30-35):(30-35):1.

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