Vitamin C phosphate-based gel catalyst as well as preparation method and application thereof

Abstract

The invention discloses a vitamin C phosphate based gel catalyst and a preparation method and application thereof, and relates to the technical field of nano material preparation and energy catalysis, the preparation method comprises the following steps: uniformly mixing a metal salt solution with an L-ascorbic acid-2-trisodium phosphate solution, and standing to form gel; the gel is subjected to vacuum freeze drying, and the vitamin C phosphate based gel catalyst is obtained; the metal types involved in the metal salt solution comprise at least one of Fe, Co, Ni, Ru and Mo; the invention also provides application of the catalyst in the field of energy catalysis. The preparation method has the beneficial effects that the preparation method is simple, the cost is lower, large-scale synthesis can be realized, the catalyst can be compounded with various self-supporting materials to serve as a self-supporting catalyst, and the catalyst has high potential industrial application value in the field of energy catalysis. The catalyst can be used for electrocatalytic water decomposition, oxygen reduction reaction, carbon dioxide reduction reaction and various organic catalytic reactions.

Description

Technical Field

[0001] The present invention relates to the field of preparation of nanomaterials and energy catalysis, and particularly relates to a vitamin C phosphate-based gel catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasing global demand for clean energy and sustainable development, electrocatalytic water splitting has received extensive attention as an efficient and environmentally friendly hydrogen production method. Although traditional electrocatalytic water splitting catalysts can achieve water splitting to a certain extent, there are still many challenges in terms of efficiency, stability, and cost. Moreover, traditional electrocatalysts mostly use precious metal materials such as platinum and iridium. Although these materials have excellent performance in the catalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), their high cost and scarce resources limit their promotion in large-scale applications.

[0003] As a new type of catalyst morphology, gel-type catalysts have shown great potential in the field of electrocatalytic water splitting due to their unique structures and properties. Gel materials have a high specific surface area, good pore structures, and adjustable chemical compositions. These characteristics enable gel-type catalysts to provide more active sites, promote charge transfer, and thus improve the efficiency of electrocatalytic water splitting. In addition, by utilizing the gel characteristics, it is easy to composite gel-type catalysts with conductive carriers to prepare self-supported electrocatalysts. The self-supported electrodes prepared from gel-type catalysts have a simple method and low cost. Since the steps of additionally using conductive agents and binders are completely omitted, not only the preparation process of the electrodes is greatly simplified, but also the catalytic activity and long-term stability of the electrodes are significantly improved. Therefore, this self-supported electrocatalyst has shown great application potential and advantages in energy conversion fields such as water electrolysis for hydrogen production.

[0004] Vitamin C phosphate, as an important derivative of vitamin C, has shown broad application prospects in multiple industries such as medicine, food, and cosmetics due to its excellent stability and high bioavailability. Innovatively integrating vitamin C phosphate into the catalyst preparation process not only because of its wide raw material sources and low cost, but also because of its non-toxic, harmless, and excellent biocompatible properties. Therefore, the gel catalyst prepared based on vitamin C phosphate is expected to become an alternative to traditional precious metal catalysts and exhibit efficient and low-cost electrocatalytic water splitting performance. This innovative achievement opens up a new path for the industrial application of electrocatalytic water splitting technology and has far-reaching significance for promoting the progress and development of the energy catalysis field. Summary of the Invention

[0005] An object of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a vitamin C phosphate-based gel catalyst, a preparation method thereof, and an application thereof.

[0006] The technical solution of the present invention is as follows: The first aspect of the present invention provides a preparation method of a vitamin C phosphate-based gel catalyst, comprising the following steps: After uniformly mixing a metal salt solution and a trisodium L-ascorbate-2-phosphate solution, standing to form a gel; Performing vacuum freeze-drying on the gel to obtain a vitamin C phosphate-based gel catalyst; Wherein, the metal types involved in the metal salt solution include at least one of Fe, Co, Ni, Ru, and Mo.

[0007] Optionally, the salt types involved in the metal salt solution include at least one of metal nitrate salts, metal sulfate salts, metal acetate salts, and metal chloride salts.

[0008] Optionally, the concentration of the metal salt solution is 0.1 mol / L to 0.5 mol / L; the concentration of the trisodium L-ascorbate-2-phosphate solution is 0.1 mol / L to 0.5 mol / L.

[0009] Optionally, the volume ratio of the metal salt solution to the trisodium L-ascorbate-2-phosphate solution is 1:5 to 5:1.

[0010] Optionally, when preparing the vitamin C phosphate-based gel catalyst containing bimetals, the metal salt solution is a mixed solution of iron nitrate or nickel nitrate and cobalt nitrate, wherein the mass ratio of iron nitrate or nickel nitrate to cobalt nitrate is 1:9 to 1:1 The second aspect of the present invention provides a vitamin C phosphate-based gel catalyst prepared by the above preparation method.

[0011] Optionally, the vitamin C phosphate-based gel catalyst is an ultrathin nanosheet with a thickness of 3 nm to 4 nm.

[0012] The third aspect of the present invention provides a preparation method of a self-supporting catalyst, comprising the following steps: When preparing the vitamin C phosphate-based gel catalyst according to the above preparation method, adding a conductive substrate to obtain a self-supporting catalyst; Wherein, the conductive substrate is at least one of carbon cloth, carbon paper, foam Fe, foam Co, foam Ni, foam Cu, and titanium mesh conductive substrate.

[0013] The fourth aspect of the present invention provides a self-supporting catalyst obtained by the above preparation method.

[0014] The fifth aspect of the present invention provides the application of the ascorbyl phosphate-based gel catalyst or the self-supported catalyst in the field of energy catalysis, including applications in water splitting reaction, oxygen reduction reaction, carbon dioxide reduction reaction, and organic catalytic reaction.

[0015] The present invention has at least one of the following beneficial effects: In the present invention, ascorbyl phosphate (sodium L-ascorbate-2-phosphate) is used as a ligand. After being uniformly mixed with an aqueous metal salt solution, a gel can be formed, named SAP-X. The ascorbyl phosphate-based gel catalyst material prepared in the present invention can be generated from metal salts such as Fe, Co, Ni, Ru, or Mo and the ligand. The morphology of the prepared ascorbyl phosphate-based gel catalyst material is ultra-thin nanosheets about 3 nm in size. The ascorbyl phosphate-based gel prepared in the present invention can be added with various conductive substrates of different sizes during preparation to obtain a self-supported catalyst SAP-X@Y. The preparation method of the present invention is simple and the preparation cost is low. Taking SAP-Co as an example, the cost of SAP-Co is only 2.5 yuan per gram, which is about one two-hundred and eightieth of the price of the current commercial catalyst RuO 2 and has high potential industrial application value.

[0016] The ascorbyl phosphate-based gel catalyst and self-supported catalyst prepared in the present invention exhibit excellent OER catalytic performance. For example, in the classical three-electrode system with 1.0 M KOH electrolyte, the sample of SAP-CoFe prepared in the present invention only requires an overpotential of 257 mV on the glassy carbon electrode to drive a current density of 10 mA·cm -2 The ascorbyl phosphate-based gel catalyst material and self-supported catalyst prepared in the present invention have high potential application value in the field of energy catalysis and can be used in other applications such as ORR, CO 2 RR and various organic catalytic reactions. Description of the Drawings

[0017] Figure 1 This is a physical photo of SAP-Co prepared in Example 1 of the present invention. Figure 2 This is the X-ray powder diffraction pattern of SAP-Co prepared in Example 1 of the present invention.

[0018] Figure 3 This is the scanning electron microscope image of SAP-Co prepared in Example 1 of the present invention.

[0019] Figure 4 This is the OER linear sweep voltammetry curve of SAP-Co on glassy carbon prepared in Example 1 of the present invention.

[0020] Figure 5 This is SAP-CoFe prepared in Example 2 of the present invention 10%Physical photos.

[0021] Figure 6 SAP-CoFe prepared in Example 2 of the present invention 10% X-ray powder diffraction pattern.

[0022] Figure 7 SAP-CoFe prepared in Example 2 of the present invention 10% Scanning electron microscope image.

[0023] Figure 8 SAP-CoFe prepared in Example 2 of the present invention 10% Transmission electron microscope image.

[0024] Figure 9 SAP-CoFe prepared in Example 2 of the present invention 10% Atomic force microscope image.

[0025] Figure 10 SAP-CoFe prepared in Example 2 of the present invention 10% OER linear sweep voltammetry curve on glassy carbon.

[0026] Figure 11 SAP-CoFe prepared in Example 2 of the present invention 10% Tafel curve.

[0027] Figure 12 SAP-CoFe prepared in Example 2 of the present invention 10% Electrochemical specific surface area diagram and C dl Diagram; where (a) is the electrochemical specific surface area diagram and (b) is C dl Diagram.

[0028] Figure 13 SAP-CoFe prepared in Example 2 of the present invention 10% Electrochemical impedance spectroscopy diagram.

[0029] Figure 14 X-ray powder diffraction pattern of SAP-CoNi prepared in Example 3 of the present invention.

[0030] Figure 15 OER linear sweep voltammetry curve on glassy carbon of SAP-CoNi prepared in Example 3 of the present invention.

[0031] Figure 16 OER linear sweep voltammetry curves on glassy carbon of SAP-CoFe with different cobalt-iron ratios prepared in Example 4 of the present invention.

[0032] Figure 17This is a physical picture of the SAP-CoFe@Y self-supporting electrode prepared in Example 4 of the present invention, wherein (a) is foamed Co, (b) is foamed Ni, (c) is titanium felt, (d) is foamed gold, and (e) is carbon cloth. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Example 1 This embodiment provides a preparation of a vitamin C phosphate-based gel catalyst SAP-Co, comprising the following steps: Prepare 0.15 mol / L cobalt nitrate solution and 0.1 mol / L L-ascorbic acid-2-trisodium phosphate solution.

[0035] The two solutions were mixed thoroughly in a volume ratio of 1:1 and allowed to stand for 30 s to form the gel catalyst SAP-Co. Figure 1 As shown by Figure 1 It can be seen that SAP-Co is in a gel-like state and does not flow when placed upside down.

[0036] The SAP-Co was quickly frozen in liquid nitrogen and transferred to a freeze dryer for freeze drying for 2 days. Finally, the freeze-dried sample was ground into powder to obtain a sample SAP-Co.

[0037] The X-ray diffraction pattern of sample SAP-Co is shown in Figure 2 ; Scanning electron microscopy images are shown in Figure 3 ,Depend on Figure 3 This indicates that the sample SAP-Co is in the form of nanosheets.

[0038] The performance test of the sample SAP-Co prepared in Example 1 was carried out, and the test method and results are as follows: The electrocatalytic OER performance test of the SAP-Co obtained in Example 1 was performed using a classic three-electrode system at room temperature on a CHI760E electrochemical workstation. The electrolyte was a 1.0M KOH solution. Hg / HgO and Pt sheets were used as reference electrodes and counter electrodes. 10 mg of SAP-Co was taken, 400 uL of water, 200 uL of n-propanol and 30 uL of Nafion were added, and after ultrasonication for 2 hours, the sample was dropped on a glassy carbon electrode as a working electrode.

[0039] Figure 4 The linear sweep voltammetry curve shown was obtained at a scan rate of 5 mV / s. It can be seen that SAP-Co drives 10 mA·cm on the glassy carbon electrode.-2 The overpotential required for the current density is 321 mV.

[0040] Example 2 This example provides a preparation of a vitamin C phosphate-based gel catalyst SAP-CoFe 10% The difference from Example 1 is only that "cobalt nitrate" is replaced with "a mixed solution of cobalt nitrate + iron nitrate (where the molar ratio of cobalt nitrate to iron nitrate is 9:1)", and the rest is the same as in Example 1. The physical diagram is as Figure 5 shown, and it can be seen from Figure 5 that SAP-CoFe 10% is in a gel state and will not flow when placed upside down.

[0041] The X-ray diffraction pattern of the sample SAP-CoFe 10% is shown in Figure 6 ; the scanning electron microscope image is shown in Figure 7 , and it can be shown from Figure 7 that the sample SAP-CoFe is in the form of nanosheets; the transmission electron microscope image is shown in Figure 8 , and it can be shown from Figure 8 that the sample SAP-CoFe 10% is in the form of ultrathin nanosheets; the atomic force microscope image is shown in Figure 9 , and it can be shown from Figure 9 that the sample SAP-CoFe 10% is an ultrathin nanosheet with a thickness of 3.42 nm.

[0042] The performance of the sample SAP-CoFe prepared in Example 2 10% was tested, and the test methods and results are as follows: (1) Electrochemical OER performance test of SAP-CoFe 10% The electrochemical OER performance test of SAP-CoFe obtained in Example 2 was carried out on a CHI760E electrochemical workstation at room temperature using a classical three-electrode system for electrochemical testing. The electrolyte was 1.0 M KOH solution. Hg / HgO and Pt sheets were used as the reference electrode and the counter electrode. 10 mg of SAP-CoFe 10% was taken, 400 μL of water, 200 μL of n-propanol and 30 μL of Nafion were added, and after ultrasonic treatment for 2 hours, the sample was dropped on the glassy carbon electrode as the working electrode. 10% The linear sweep voltammetry curve shown in

[0043] Figure 10 was obtained at a scan rate of 5 mV / s. It can be seen from the figure that the overpotential required for SAP-CoFe 10% to drive a current density of 10 mA·cm -2 on the glassy carbon electrode is 257 mV.Figure 11 The Tafel curve shown is obtained from Figure 10 calculation, and it can be seen that the Tafel slope of SAP-CoFe 10% on the glassy carbon electrode is 46.0 ± 0.5 mV·dec -1 .

[0044] (2) Electrochemical specific surface area test of SAP-CoFe 10% To determine the electrochemical surface area (ECSA), cyclic voltammetry (CV) measurements were used to investigate the electrochemical double-layer capacitance (C ) of the prepared electrodes. CV was carried out in the non-Faradaic range (1.10 - 1.20 V vs RHE) with scan rates of 40 mV·s dl , 60 mV·s -1 , 80 mV·s -1 , 100 mV·s -1 , and 120 mV·s -1 . By plotting the relationship between the current density and the scan rate at 1.10 - 1.20 V vs RHE, C -1 is half of the slope of the linear graph and is used to represent the ECSA. The electrochemical specific surface area graph is shown in dl (a) in Figure 12 . From Figure 12 (a), the C 10% of the sample SAP-CoFe dl was calculated to be 42.1 ± 0.15 mF·cm -2 , as shown specifically in Figure 12 (b).

[0045] (3) Electrochemical impedance spectroscopy test of SAP-CoFe 10% Electrochemical impedance spectroscopy (EIS) measurements were carried out in the frequency range of 0.01 Hz to 100 kHz. The electrochemical impedance spectroscopy graph is shown in . From Figure 13 , it can be shown that the impedance of the sample SAP-CoFe Figure 13 is relatively small. 10%

[0046] Example 3 This example provides the preparation of a vitamin C phosphate-based gel catalyst SAP-CoNi, which is only different from Example 1 in that "cobalt nitrate" is replaced with "a mixed solution of cobalt nitrate + nickel nitrate (where the molar ratio of cobalt nitrate to nickel nitrate is 2:1)", and the others are the same as in Example 1.

[0047] The X-ray diffraction pattern of the sample SAP-CoNi is shown in Figure 14 ; The performance test of the sample SAP-CoNi prepared in Example 3 was carried out, and the test methods and results are as follows: (1)Electrocatalytic OER Performance Test of SAP-CoNi The electrocatalytic OER performance test of SAP-CoNi obtained in Example 3 was carried out on a CHI760E electrochemical workstation at room temperature using a classical three-electrode system for electrochemical testing. The electrolyte was 1.0 M KOH solution. Hg / HgO and Pt sheet were used as the reference electrode and the counter electrode. 10 mg of SAP-CoNi was taken, 400 μL of water, 200 μL of n-propanol and 30 μL of Nafion were added, and after ultrasonic treatment for 2 hours, the sample was dropped on a glassy carbon electrode as the working electrode.

[0048] Figure 15 The linear sweep voltammetry curve shown was obtained at a scan rate of 5 mV / s. It can be seen from the figure that the overpotential required for SAP-CoNi to drive 10 mA·cm -2 current density on the glassy carbon electrode was 304 mV.

[0049] Example 4 The difference from Example 2 was only that: "in the mixed solution of cobalt nitrate + iron nitrate, the molar proportion of iron nitrate was changed from 10% to 2.5%, 5% and 12% respectively", and SAP-CoFe 2.5% 、SAP-CoFe 5% and SAP-CoFe 12% were obtained respectively.

[0050] The OER linear sweep voltammetry curves of SAP-CoFe with different cobalt-iron ratios on glassy carbon are shown in Figure 16 It can be seen that SAP-CoFe 2.5% 、SAP-CoFe 5% 、SAP-CoFe 10% and SAP-CoFe 12% all had certain catalytic performances. Among them, compared with SAP-CoFe 2.5% 、SAP-CoFe 5% and SAP-CoFe 12% , the sample SAP-CoFe 10% had the best catalytic performance.

[0051] Example 5 This example provides a preparation method of SAP-CoFe@Y self-supporting electrode, including the following steps: When preparing the vitamin C phosphate-based gel catalyst in Example 2, carbon cloth, gold foam, cobalt foam, nickel foam and titanium felt conductive substrates were added respectively to obtain the self-supporting catalyst SAP-CoFe@Y.

[0052] The physical diagram is shown in Figure 17 , whereFigure 17 Among them, (a) is foam Co, (b) is foam Ni, (c) is titanium felt, (d) is foam Au, and (e) is carbon cloth.

[0053] For the first time, L-ascorbic acid-2-phosphate trisodium is selected as a ligand to prepare a vitamin C phosphate-based gel catalyst material. Through simple methods of mixing, stirring, and freeze-drying, a vitamin C phosphate-based gel nanocomposite SAP-CoX (X = transition metals such as Fe, Ni, Ru, Mo; SAP: abbreviation of L-ascorbic acid-2-phosphate trisodium) with a high phosphorus content (about 0.3 wt%) and an ultrathin scale (3 nm - 4 nm) can be prepared in large quantities. The preparation method of this vitamin C phosphate-based gel nanocomposite catalyst is simple and has a low cost, suitable for large-scale synthesis, and has high potential industrial application value in the field of energy catalysis. It can be used in electrocatalytic water splitting reactions, oxygen reduction reactions (ORR), carbon dioxide reduction reactions (CO 2 RR), and various organic catalytic reactions. Moreover, self-supported catalysts SAP-X@Y can be obtained by adding various conductive substrates with different sizes during the preparation of the vitamin C phosphate-based gel catalyst. Among them, Y can be conductive substrates such as carbon cloth, carbon paper, foam Fe, foam Co, foam Ni, foam Cu, and titanium mesh.

[0054] Taking electrocatalytic water splitting as an example, since hydrogen has a high energy density and is clean and environmentally friendly, the technology of electrocatalytic water splitting to produce hydrogen has broad application prospects. Water splitting includes two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, both of which require the introduction of a catalyst to reduce the reaction overpotential in the electrocatalytic reaction and improve the reaction efficiency. Some noble metals and their oxides are currently recognized as excellent electrolytic water catalysts. However, due to the scarcity of such catalysts and high costs, their commercial applications are greatly limited. SAP-CoFe has excellent OER electrocatalytic performance, which is superior to the current commercial catalyst RuO 2 and the cost is only about 1 / 280 of the price of RuO 2 . The electrocatalytic water splitting can reach a current density of 10 mA·cm -2 with an overpotential of only 257 mV.

[0055] As described above, only the preferred specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a vitamin C phosphate-based gel catalyst, characterized in that: The following steps are involved: The metal salt solution and the L-ascorbic acid-2-trisodium phosphate solution are uniformly mixed and allowed to stand to form a gel; The gel is subjected to vacuum freeze drying to obtain a vitamin C phosphate-based gel catalyst; Wherein, the metal types involved in the metal salt solution include at least one of Fe, Co, Ni, Ru and Mo.

2. The preparation method according to claim 1, characterized in that: The salt type involved in the metal salt solution includes at least one of metal nitrate, metal sulfate, metal acetate and metal chloride.

3. The preparation method according to claim 1, characterized in that: The concentration of the metal salt solution is 0.1 mol / L to 0.5 mol / L; the concentration of the L-ascorbic acid-2-trisodium phosphate solution is 0.1 mol / L to 0.5 mol / L.

4. The preparation method according to claim 1, characterized in that: The volume ratio of the metal salt solution to the L-ascorbic acid-2-trisodium phosphate solution is 1:5-5:

1.

5. The preparation method according to claim 1, characterized in that: When preparing the bimetallic vitamin C phosphate-based gel catalyst, the metal salt solution is a mixed solution of ferric nitrate or nickel nitrate and cobalt nitrate, wherein the mass ratio of ferric nitrate or nickel nitrate to cobalt nitrate is 1:9-1:

1.

6. A vitamin C phosphate-based gel catalyst, characterized in that: The method is prepared by any one of claims 1 to 5.

7. The vitamin C phosphate-based gel catalyst according to claim 6, characterized in that: The vitamin C phosphate-based gel catalyst is an ultra-thin nanosheet with a thickness of 3 nm to 4 nm.

8. A method for preparing a self-supporting catalyst, characterized in that: The following steps are involved: When preparing the vitamin C phosphate-based gel catalyst according to the preparation method of claim 1, adding a conductive substrate to obtain a self-supporting catalyst; Wherein, the conductive substrate is at least one of carbon cloth, carbon paper, foam Fe, foam Co, foam Ni, foam Cu, and titanium mesh conductive substrate.

9. A self-supporting catalyst, characterized in that The preparation method according to claim 8 is used to obtain the 10. Use of the vitamin C phosphate-based gel catalyst according to claim 6 or the self-supporting catalyst according to claim 9 in the field of energy catalysis, characterized in that: Including applications in water decomposition reactions, oxygen reduction reactions, carbon dioxide reduction reactions and organic catalytic reactions.

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