Oxygen-deficient iron / tin heterojunction nano electro-catalytic material as well as preparation method and application of oxygen-deficient iron / tin heterojunction nano electro-catalytic material

Abstract

The invention discloses an oxygen-deficient iron / tin heterojunction nano electro-catalytic material and a preparation method and application thereof, and belongs to the technical field of electro-catalytic materials.The preparation method comprises the steps that 1, after foamed nickel is pretreated, the foamed nickel is added into a mixed solution of ferric salt, terephthalic acid, deionized water and an organic solvent, a hydrothermal reaction is conducted for 15-30 hours at the temperature of 100-150 DEG C, and the foamed nickel is obtained; reacting to obtain a precursor; and (2) constructing a reaction system comprising the precursor in the step (1), tin salt, sodium citrate and an ethanol water solution, placing the reaction system at 150-210 DEG C for hydrothermal reaction for 6-18 hours, and annealing the obtained product in an inert gas atmosphere at 400-600 DEG C for 3-6 hours to prepare the oxygen-deficient iron / tin heterojunction nano electro-catalytic material. The electro-catalytic material has good catalytic activity and high durability, and can be used as an electro-catalytic anode material based on LOM.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and in particular relates to an oxygen-deficient iron / tin heterojunction nano electrocatalytic material and a preparation method and application thereof. Background Art

[0002] Today's society has a huge demand for energy, and the reserves of traditional fossil fuels are limited. The development of a new fuel energy that can replace traditional fossil fuels and is cleaner, more efficient, and cheaper has become a key issue that needs to be solved urgently, and its urgency cannot be ignored. Hydrogen energy, as a renewable energy source, has a wide range of sources and can be produced through various methods such as water electrolysis, natural gas reforming, and biomass conversion. Hydrogen energy also has the advantages of being green, environmentally friendly, zero carbon emissions, and high energy density. It is considered to be one of the most critical new fuel energy sources for energy transformation.

[0003] Using natural energy (solar energy, wind energy, tidal energy, etc.) to generate clean electricity and using water as raw material for electrochemical catalytic hydrogen production is a key link in realizing the application of hydrogen energy. Generally, electrocatalytic hydrogen production requires the complete decomposition of water, which involves the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The OER occurring on the traditional anode follows the adsorption evolution mechanism (AEM) and needs to go through four slow electron transfer steps. The production of three key intermediates (adsorbed oxygen, adsorbed hydroxyl, and adsorbed peroxide ions) has a large energy barrier (theoretical overpotential minimum limit is 370 mV), which greatly reduces the production efficiency and economic benefits of electrocatalytic hydrogen production. To this end, scientists have proposed to use the activation of lattice oxygen in anode catalytic materials and participate in redox in OER, so that OER triggers and follows the lattice oxygen evolution mechanism (LOM), thereby circumventing the limitations of AEM, reducing energy barriers, and improving the efficiency and benefits of electrocatalytic hydrogen production.

[0004] For example, a Chinese patent document with publication number CN118127559A discloses a high-valent metal-doped Co4N catalyst, the preparation method of which includes: using nickel foam as a substrate to prepare Mn-doped cobalt nanowires uniformly grown on a nickel foam substrate by hydrothermal synthesis, and then performing nitridation treatment to obtain Mn-doped Co4N nanowires grown on nickel foam, using it as an electrode material, and reconstructing its surface by cyclic voltammetry technology to finally obtain a Mn-doped CoO2 / Co4N composite material. Mn can adjust the oxygen 2P orbital to move up over the Fermi level, thereby activating the lattice oxygen on the catalyst surface, allowing it to participate in the reaction, and finally inducing the lattice oxygen reaction path.

[0005] The results of existing research indicate that increasing the covalency of metal-oxygen (MO) bonds is the key to triggering the lattice oxygen oxidation reaction. (LOM)), researchers have tried many modification strategies, such as constructing heterojunctions, defect engineering, energy band regulation, and cocatalyst modification. Among them, constructing heterojunction materials has been proven to be a promising method, which not only captures electrons from catalytic materials to inhibit charge recombination but also provides sufficient active sites to accelerate the catalytic reaction rate. At the same time, OER (LOM) requires a large number of surface oxygen vacancies (Ov) of the material as the reaction space, and it is also crucial to increase the Ov on the material surface by defect engineering.

[0006] However, during OER (LOM) process, unsaturated M-O adsorption sites are generated, causing the leaching of metal substances on the surface, which results in a generally short service life of electrocatalytic materials. Therefore, developing robust OER (LOM) electrocatalysts has become a research hotspot in the field of electrochemical catalytic material technology. Summary of the Invention

[0007] The present invention provides a preparation method of an oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material. The method is simple, efficient, easy to implement, and has relatively mild reaction conditions. The prepared oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material has good conductivity and catalytic activity, high durability, and abundant surface Ov, and can be used as an electrocatalytic anode material based on LOM and has good potential application value.

[0008] The specific technical solution adopted is as follows: A preparation method of an oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material, which can be expressed as Fe2O3@SnO2-Ov / NF, where Ov represents the surface oxygen vacancy of the material. The method includes the following steps: (1) After pretreating nickel foam, add it to a mixed solution of iron salt, terephthalic acid, deionized water, and organic solvent, and carry out a hydrothermal reaction at 100-150 °C for 15-30 hours to obtain a precursor; the precursor includes MIL-53(Fe) grown on the nickel foam substrate; (2) Construct a reaction system including the precursor in step (1), tin salt, sodium citrate, and ethanol aqueous solution, place the reaction system at 150-210 °C for a hydrothermal reaction for 6-18 hours, and anneal the obtained product in an inert gas atmosphere at 400-600 °C for 3-6 hours to prepare the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material.

[0009] The combination of Fe2O3 and SnO2 in the present invention helps to develop a durable, low-cost, and well-performing electrocatalytic material. On the one hand, the presence of Fe can induce the downward shift of the metal d-band to penetrate the 2p-band of the oxygen ligand, increasing the covalency of the metal-oxygen (M-O), thereby triggering the LOM path of OER and inhibiting the dissolution of metal substances. On the other hand, Sn has a relatively high electronegativity (1.96), and a high electronegativity is also one of the key factors to enhance the covalency of M-O. The synergistic effect of Fe and Sn elements enhances the covalency of the M-O bond, and SnO2 also has strong catalytic performance. Incorporating SnO2 into the iron-based material and constructing a heterojunction can greatly improve the LOM electrocatalytic performance of the material; further, after high-temperature annealing, the SnO2 crystal loses a large number of oxygen atoms to form abundant surface oxygen vacancies (Ov), and it can maintain the integrity of the crystal structure by forming electron defects and forming Sn 4+ vacancy pairs, which also provides sufficient reaction space for OER (LOM) and improves the catalytic activity of the material, maximizing its application potential.

[0010] Preferably, the pretreatment steps of the nickel foam include: placing the nickel foam in deionized water, dilute hydrochloric acid, and absolute ethanol for cleaning respectively, and storing it in absolute ethanol for standby after cleaning to prevent oxidation.

[0011] Specifically, in step (1), the organic solvents used are N,N-dimethylformamide (DMF) and absolute ethanol, and the volume ratio of N,N-dimethylformamide, absolute ethanol, and deionized water is 9-18 : 1 : 1.

[0012] Preferably, in step (1), the dosage of the iron salt is controlled such that the content of Fe 3+ in every 40 ml of the solvent (including deionized water and organic solvents) is 1-2 mM, and the molar mass ratio of terephthalic acid to Fe 3+ is 1-2 : 1.

[0013] Most preferably, in step (1), the hydrothermal reaction conditions are 125 °C and 24 hours.

[0014] Preferably, after the preparation of the precursor, it is rinsed three times with anaerobic deionized water and then vacuum dried. After drying, it is stored in a vacuum chamber under vacuum for standby.

[0015] Preferably, in step (2), the dosage of the tin salt is controlled such that the content of Sn 2+ in every 40 ml of the ethanol aqueous solution is 0.5-1 mM; the molar mass ratio of Fe 3+ in the precursor, Sn 2+ in the tin salt, and sodium citrate is 2 : 1-2 : 1-4.

[0016] Most preferably, in step (2), the hydrothermal reaction conditions are 180 °C and 12 hours.

[0017] Optionally, the inert gas atmosphere is an argon atmosphere, the heating rate during annealing is 5 - 10 °C / minute, and the calcination conditions are most preferably 500 °C and 3 hours.

[0018] Further preferably, the iron salt is iron nitrate and the tin salt is stannous chloride.

[0019] Preferably, after the preparation of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material, it is rinsed with anaerobic deionized water and then vacuum dried. After drying, it is placed in a vacuum chamber for vacuum storage.

[0020] The present invention also provides an oxygen-deficient iron / tin heterojunction nano electrocatalytic material prepared by the preparation method of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material described above, wherein oxygen-deficient heterojunction nanosheets composed of Fe2O3 and SnO2 grow orderly on a nickel foam substrate.

[0021] The present invention also provides the application of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material in water electrolysis.

[0022] The present invention also provides a method for water electrolysis using the oxygen-deficient iron / tin heterojunction nano electrocatalytic material.

[0023] Preferably, after the oxygen-deficient iron / tin heterojunction nano electrocatalytic material is tableted under a pressure of 10 - 20 MPa, it is used as an anode working electrode in the OER reaction. Tableting makes the electrode have stronger plasticity. Without tableting, the large volume will affect the overall conductivity.

[0024] During the water electrolysis hydrogen evolution reaction with Fe2O3@SnO2-Ov / NF as the anode, the intermediate O2 unique to the LOM path was successfully captured, 2- proving that the OER process of this electrode successfully triggers the LOM mechanism. Currently, most of the hydrogen production anodes on the market are RuO2 electrodes. Under the condition of the same electrode area, the electrocatalytic efficiency and hydrogen evolution kinetics of the Fe2O3@SnO2-Ov / NF electrode are much stronger than those of the RuO2 electrode, and it has strong stability.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The oxygen-deficient iron / tin heterojunction nano electrocatalytic material prepared by the method of the present invention is an anode catalytic material that can induce OER, (LOM) which can avoid the limitations of AEM, reduce the energy barrier, and improve the efficiency and benefit of electrocatalytic hydrogen production.

[0026] (2) The oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material obtained by the method of the present invention through a simple synthesis route can be directly used as an electrocatalytic anode material; based on the transition metal element iron, Fe2O3@SnO2 heterojunction is in-situ grown on nickel foam, realizing the synchronous improvement of the durability and electrocatalytic performance of the electrocatalytic material; at the same time, by using defect engineering, a rich amount of oxygen vacancies (Ov) is created on the surface of the heterojunction material, promoting the triggering of the LOM pathway of OER and reducing the energy barrier of OER. When the Fe2O3@SnO2-Ov / NF electrode is used as the anode material for simulated electrochemical hydrogen production, it has the advantages of long service life, high catalytic efficiency, and low energy consumption; it alleviates the problem that the service life of electrocatalytic materials is generally short due to the leaching of metal substances on the surface.

[0027] (3) The oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material prepared by the method of the present invention has good electrocatalytic performance, high durability, and rich Ov after being pressed into an electrode, and has a low energy barrier for the Tafel reaction step, and has the potential to become a practical OER (LOM) electrocatalytic anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 In (a) is the XRD pattern of the precursor MIL-53(Fe), and in (b) are the XRD patterns of Fe2O3@SnO2-Ov in Example 1, Fe2O3 in Comparative Example 4, Fe2O3 in Comparative Example 2, and SnO2 in Comparative Example 3.

[0029] Figure 2 are the surface SEM images of electrocatalytic materials of different products, where (a) is Example 1, (b) is Comparative Example 2, and (c) is Comparative Example 3.

[0030] Figure 3 are the EPR spectra of the sample electrodes prepared in Example 1 and different comparative examples.

[0031] Figure 4 are the LSV cyclic diagrams of the sample electrodes prepared in Example 1 and different comparative examples.

[0032] Figure 5 are the Tafel energy barrier diagrams of the sample electrodes prepared in Example 1 and different comparative examples.

[0033] Figure 6 is the stability test diagram of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the objectives, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description through specific embodiments. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined correspondingly without conflict.

[0035] For the operation methods without specific conditions noted in the following embodiments, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. The experimental materials used in the following embodiments can be obtained from regular biochemical reagent companies without special instructions.

[0036] Example 1 (1) Preparation of fresh nickel foam (NF) substrate: Cut the 2-mm-thick NF into sheets with a length of 4 cm and a width of 3.5 cm. First, ultrasonically clean it in deionized water for 30 minutes, then ultrasonically acid-wash it with dilute hydrochloric acid (obtained by diluting 37% concentrated hydrochloric acid and deionized water at a volume ratio of 1:3) for 120 minutes. After acid-washing, simply filter and wash it in 500 ml of deionized water for 10 seconds, and finally wash it thoroughly with absolute ethanol and store it in absolute ethanol for later use.

[0037] (2) Preparation of MIL-53(Fe) / NF intermediate: Mix 1 mM Fe(NO3)3 and 1 mM terephthalic acid (TPA) evenly and pour them into 35 ml of N,N-dimethylformamide (DMF), stir for 60 minutes, then add 2.5 ml of absolute ethanol and 2.5 ml of deionized water and continue to stir for 60 minutes to obtain a mixed solution. Pour the mixed solution into a high-pressure reaction kettle, add the fresh NF prepared in step (1), and let it stand for 5 minutes. After the NF is fully in contact with the solution, tighten the reaction kettle. Place the reaction kettle in a constant-temperature oven and carry out a hydrothermal reaction at 125 °C for 24 hours. After the reaction, take out the reaction kettle and let it cool naturally to room temperature. Then take out the reaction product, wash it thoroughly with deionized water, and after vacuum drying at 60 °C, obtain the flaky material MIL-53(Fe) / NF.

[0038] (3) Preparation of Fe2O3@SnO2 / NF: After mixing 0.5 mM SnCl2 and 0.9175 mM sodium citrate uniformly, pour them into 40 ml of ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), stir for 60 minutes, pour the mixed solution into a high-pressure reactor, add the MIF-53(Fe) / NF prepared in step (2), and let it stand for 5 minutes. After the MIF-53(Fe) / NF is fully contacted with the solution, tighten the reactor. Place the reactor in a constant-temperature oven and carry out hydrothermal reaction at 180 °C. After 12 hours of reaction, take out the reactor, cool it naturally to room temperature, then take out the material, wash it thoroughly with deionized water, and after vacuum drying at 60 °C, obtain the flake material Fe2O3@SnO2 / NF.

[0039] (4)Preparation of Fe2O3@SnO2-Ov / NF: Place Fe2O3@SnO2 / NF in a tubular furnace. Under the environment of continuously introducing argon, heat it to 500 °C at a rate of 5 °C per minute, and after high-temperature annealing for 3 hours, obtain the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material Fe2O3@SnO2-Ov / NF.

[0040] (5)Preparation of the working electrode: After subjecting the Fe2O3@SnO2-Ov / NF obtained in step (4) to tablet pressing treatment under a pressure of 10.0 Mpa, obtain the Fe2O3@SnO2-Ov / NF electrode.

[0041] Comparative Example 1 Use the NF flake without loading any material as the sample of Comparative Example 1.

[0042] Comparative Example 2 Use the pressed Fe2O3 / NF flake material as the sample of Comparative Example 2, denoted as the Fe2O3 / NF electrode. The difference between the preparation method of Fe2O3 / NF in this comparative example and the preparation method of MIL-53(Fe) / NF in the example is only that: the temperature of the hydrothermal reaction is 180 °C.

[0043] Comparative Example 3 After mixing 0.5 mM SnCl2 and 0.9175 mM sodium citrate uniformly, pour them into 40 ml of ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), stir for 60 minutes, pour the mixed solution into a high-pressure reactor, add fresh NF, and after the NF is fully contacted with the solution, tighten the reactor. Place the reactor in a constant-temperature oven and carry out hydrothermal reaction at 180 °C. After 12 hours of reaction, take out the reactor, cool it naturally to room temperature, then take out the material, wash it thoroughly with deionized water, and after vacuum drying at 60 °C, obtain the flake material SnO2 / NF. Use the pressed SnO2 / NF flake material as the sample of Comparative Example 3, denoted as the SnO2 / NF electrode.

[0044] Comparative Example 4 Using the Fe2O3@SnO2 / NF prepared in step (3) of Example 1 after tabletting treatment as the sample of Comparative Example 4, denoted as the Fe2O3@SnO2 / NF electrode.

[0045] Comparative Example 5 Using a traditional commercial RuO2 electrode as the sample of Comparative Example 5.

[0046] Sample Analysis The samples of the above examples and comparative examples were subjected to electrochemical hydrogen evolution tests in the following manner: An electrochemical hydrogen evolution test was carried out using a Shanghai Chenhua electrochemical workstation. A 1 mol / L KOH solution was used as the electrolyte, an Ag / AgCl electrode was used as the reference electrode, a stainless steel electrode was used as the counter electrode, and the sample electrodes prepared in the examples and comparative examples were used as the working electrodes. First, the electrolyte was purged with nitrogen for 30 minutes, and then the electrochemical hydrogen evolution performance test was carried out.

[0047] The overpotentials of the electrochemical tests of each example and comparative example (when the current density reaches 10 mA / cm 2 ) are shown in Table 1.

[0048] Table 1 Electrochemical Hydrogen Evolution Test Results

[0049] It can be analyzed from Table 1 that the performance of the Fe2O3@SnO2-Ov / NF sample in Example 1 is the best, and the overpotential is lower than that of the Fe2O3@SnO2 / NF sample in Comparative Example 3 and the traditional commercial RuO2 electrode, which confirms that the abundant Ov improves the electrocatalytic performance and has good industrial application potential. The overpotential of the sample in Comparative Example 4 is lower than that of the Fe2O3 / NF samples and SnO2 / NF samples in Comparative Examples 2 and 3, which confirms the improvement of the electrocatalytic performance by the synergistic effect of Fe and Sn.

[0050] Figure 1 In (a) is the XRD pattern of MIL-53(Fe), and in (b) are the XRD patterns of Fe2O3@SnO2-Ov in Example 1, Fe2O3@SnO2 in Comparative Example 4, Fe2O3 in Comparative Example 2, and SnO2 in Comparative Example 3. Among them Figure 1 In (a) shows the successful synthesis of the MIL-53(Fe) precursor in step (2) of the example; Figure 1 In (b) shows that the electrodes of Example 1 and Comparative Example 4 simultaneously have the XRD signals of Fe2O3 and SnO2, which are coupled products of the two metal oxides, indicating the successful formation of the Fe2O3@SnO2 heterojunction electrode; Figure 1In (b), the XRD signals of Fe2O3 and SnO2 are also shown for the electrodes of Comparative Examples 2 and 3, which are high-purity articles of single metals, indicating the successful formation of the electrodes of Comparative Examples 2 and 3.

[0051] Figure 2 Figure 4 shows the surface SEM characterization diagrams of the Fe2O3@SnO2-Ov / NF heterojunction electrode in Example 1 and the Fe2O3 / NF and SnO2 / NF electrodes involved in Comparative Examples 2 and 3. The electrodes of Comparative Examples 2-3 were characterized at different magnifications by SEM. Figure 2 In (b) of Figure 2 Figure 5, and the SEM images in (c) clearly show that Fe2O3 and SnO2 on the electrodes exhibit "nanosheet-like" and "nanospherical" morphologies, respectively. The electrodes of Example 1 were characterized at different magnifications by SEM. Figure 2 The SEM image in (a) of Figure 6 can clearly observe two morphologies of nanosheet-like Fe2O3 and nanospherical SnO2, and the nanospherical SnO2 and nanosheet-like Fe2O3 are closely interlocked, confirming the formation of the Fe2O3@SnO2 heterojunction structure.

[0052] Figure 3 Figure 7 shows the EPR characterization diagrams of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, the Fe2O3 / NF electrode prepared in Comparative Example 2, the SnO2 / NF electrode prepared in Comparative Example 3, and the Fe2O3@SnO2 / NF electrode prepared in Comparative Example 4. Among them, the signal peak of the Fe2O3@SnO2-Ov / NF electrode at g = 2.003 is significantly stronger than that of other electrodes, indicating that the surface of this electrode has the most Ov, suggesting its strong electrocatalytic potential.

[0053] Figure 4 Figure 8 shows the LSV curves of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, the NF electrode prepared in Comparative Example 1, the Fe2O3 / NF electrode prepared in Comparative Example 2, the SnO2 / NF electrode prepared in Comparative Example 3, the Fe2O3@SnO2 / NF electrode prepared in Comparative Example 4, and the traditional commercial RuO2 electrode in Comparative Example 5, with MIL-53(Fe) / NF as a comparison. Among them, the overpotentials of the electrodes in Example 1 are significantly lower than those of the electrodes in other comparative examples, indicating their excellent hydrogen evolution performance, confirming the synergistic effect of Sn and Fe and the improvement of electrocatalytic performance by a large number of Ov on the surface. At the same time, it shows that the catalytic performance of the Fe2O3@SnO2-Ov / NF electrode prepared in the present invention is much higher than that of the traditional commercial RuO2 electrode, having good application prospects.

[0054] Figure 5Tafel slope diagrams of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, the Fe2O3 / NF electrode prepared in Comparative Example 2, the SnO2 / NF electrode prepared in Comparative Example 3, the Fe2O3@SnO2 / NF electrode prepared in Comparative Example 4, and the traditional commercial RuO2 electrode in Comparative Example 5. The j in the abscissa represents the current density. Among them, the Fe2O3@SnO2-Ov / NF electrode has the lowest slope value of 57.5 mV / dec under the synergistic effect of Sn and Fe and the promotion of a large number of oxygen vacancies on the surface, indicating its good hydrogen evolution kinetics.

[0055] Figure 6 For the stability test of the Fe2O3@SnO2-Ov / NF electrode prepared in Example 1, under the working condition of a voltage of 1.5 V, the electrode continuously works for 120 hours, and its current density changes from 106.68 mA to 93.84 mA, maintaining 88% of the starting current, indicating that the catalytic performance of the electrode is still good and basically meets the requirements of the market for electrode materials.

[0056] In summary, the heterojunction electrocatalytic anode material Fe2O3@SnO2-Ov rich in oxygen vacancies was synthesized by defect engineering and loaded on nickel foam, demonstrating high-efficiency and stable hydrogen production potential. Currently, most of the hydrogen production anodes on the market are RuO2 electrodes. Under the condition of the same electrode area, the electrocatalytic efficiency and hydrogen evolution kinetics of the Fe2O3@SnO2-Ov / NF electrode are much stronger than those of the RuO2 electrode. When the current density reaches 10 mA / cm 2 2, the overpotential of the Fe2O3@SnO2-Ov / NF electrode is only 171 mV, while the overpotential of the commercial RuO2 electrode on the market is as high as 367 mV. In addition, the lowest value of the Tafel slope of Fe2O3@SnO2-Ov / NF is 57.5 mV / dec, while the Tafel slope value of the commercial RuO2 electrode on the market is as high as 102 mV / dec. At the same time, the Fe2O3@SnO2-Ov / NF electrode can maintain the current density at about 93 - 106 mA / cm 2 2 at a constant potential of 1.5 V and continuously work for 120 hours, with only small current fluctuations and degradation, basically meeting the requirements of commercial hydrogen production.

[0057] The above-described embodiments have detailed the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, supplements, or substitutions in a similar manner within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation method of an oxygen-deficient iron / tin heterojunction nano electrocatalytic material, characterized in that, It includes the following steps: (1) After pretreating nickel foam, add it to a mixed solution of iron salt, terephthalic acid, deionized water and organic solvent, and carry out a hydrothermal reaction at 100 - 150 °C for 15 - 30 hours to obtain a precursor; the precursor includes MIL-53(Fe) grown on the nickel foam substrate; (2) Construct a reaction system including the precursor in step (1), tin salt, sodium citrate and ethanol aqueous solution, place the reaction system at 150 - 210 °C for a hydrothermal reaction for 6 - 18 hours, and anneal the obtained product at 400 - 600 °C for 3 - 6 hours under an inert gas atmosphere to prepare the oxygen-deficient iron / tin heterojunction nano electrocatalytic material.

2. The preparation method of the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material according to claim 1, wherein The pretreatment steps of nickel foam include: placing nickel foam in deionized water, dilute hydrochloric acid and absolute ethanol for cleaning respectively.

3. The preparation method of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to claim 1, characterized in that, In step (1), the organic solvent is selected from N,N-dimethylformamide and absolute ethanol, and the volume ratio of N,N-dimethylformamide, absolute ethanol and deionized water is 9 - 18 : 1 :

1.

4. The preparation method of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to claim 1, wherein, In step (1), the dosage of iron salt is controlled such that the content of Fe in every 40 ml of solvent is 1 - 2 mM, and the molar mass ratio of terephthalic acid to Fe 3+ is 1 - 2 :

1. 3 + ​ 5. The preparation method of the oxygen-deficient iron / tin heterojunction nanoelectrocatalytic material according to claim 1, wherein, In step (2), the dosage of tin salt is controlled such that the content of Sn in every 40 ml of ethanol aqueous solution is 0.5 - 1 mM; the molar mass ratio of Fe in the precursor, Sn in the tin salt, and sodium citrate is 2 : 1 - 2 : 1 - 4. 2+ 3+ 2+ ​ 6. The preparation method of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to claim 1, wherein The inert gas atmosphere is an argon atmosphere, and the heating rate during annealing is 5 - 10 °C / minute.

7. The preparation method of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to claim 1, characterized in that, The iron salt is ferric nitrate, and the tin salt is stannous chloride.

8. The oxygen-deficient iron / tin heterojunction nano electrocatalytic material prepared by the preparation method of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to any one of claims 1 - 7.

9. The application of the oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to claim 8 in water electrolysis.

10. A method for electrolyzing water, characterized in that, The oxygen-deficient iron / tin heterojunction nano electrocatalytic material according to claim 8 is used as an anode material after being pressed into a tablet.

Images