Lattice-distorted fluorine-doped titanium-based gas diffusion electrode, preparation method and application thereof

Abstract

The invention discloses a lattice-distorted fluorine-doped titanium-based gas diffusion electrode, a preparation method and application thereof, an electrode material is a fluorine-doped titanium oxide electrode material and has a titanium oxide octahedral unit cell distorted structure, and the size of the electrode material is 20-50nm; the electrode material is loaded on a carbon substrate and treated to obtain the gas diffusion electrode. When the electrode is applied to a cathode of an electrolytic tank, the electrode shows excellent performance of electrocatalytic reduction synthesis of hydrogen peroxide resistant to acid and alkali electrolyte, the twisting degree of the titanium dioxide octahedron in the electrode can be adjusted by regulating and controlling experimental parameters, the endurance capacity of the electrode to strong acid and alkali electrolyte is enhanced, and the service life of the electrode is prolonged. The ultrahigh gas mass transmission efficiency and oxygen utilization rate are realized, and the high energy loss of the pH of the electrolyte on the electrode is avoided.

Description

Technical Field

[0001] The invention relates to a titanium-based gas diffusion electrode, belonging to the technical field of electrode preparation. Background Art

[0002] Hydrogen peroxide (H 2 O 2 ) is not only a valuable oxidant for a variety of chemical processes, but also a clean fuel with an energy density comparable to that of hydrogen. It also has great prospects in a variety of applications including chemical synthesis, water treatment, pulp / paper bleaching, aircraft propulsion, disinfection, etc. Due to the rapid growth in demand for hydrogen peroxide, the annual production was 9.07 million tons in 2017 and reached 13.5 million tons by 2022. The industrial production method of hydrogen peroxide technology usually adopts the anthraquinone method, but the anthraquinone method is not suitable for industrial-scale production of H 2 O 2 It is quite energy-intensive and involves multiple steps, large amounts of organic solvents, large amounts of waste and explosion hazards. Therefore, the issue of how to produce hydrogen peroxide in a "green" way has attracted more and more attention. In the 1930s, Berl first reported the electrochemical 2e - Small-scale scene H 2 O 2 Production route oxygen reduction reaction (2e - ORR, O 2 +2H + +2e - →H 2 O 2 ), further developed by Dow and Huron Technologies, Inc., and commercialized in 1991. Since then, electrochemical H 2 O 2 The production strategy has attracted increasing research interest as a potential alternative to traditional anthraquinone redox processes.

[0003] To our knowledge, currently, all reported 2e - ORR catalysts cannot maintain excellent activity when the pH changes. Therefore, it is necessary to develop new pH-resistant catalysts for 2e - The large-scale practical utilization of ORR is of great significance. Summary of the invention

[0004] The purpose of the present invention is to provide a titanium-based gas diffusion electrode material and a preparation method thereof, and application thereof in the rapid electrocatalytic reduction of oxygen to synthesize hydrogen peroxide by strong alkali and strong acid.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A sub-nano titanium-based unit cell distorted gas diffusion electrode material and a preparation method thereof, comprising the following steps:

[0007] Step 1: dissolving ammonium fluoride and concentrated hydrochloric acid in ethanol and stirring to form a uniform mixed solution;

[0008] Step 2: adding tetraisopropyl titanate to the mixed solution obtained in step 1 and stirring to form a uniform mixed solution;

[0009] Step 3: placing the solution obtained in step 2 in a closed environment for hydrothermal reaction for a period of time, and then centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material.

[0010] Furthermore, the molar ratio of tetraisopropyl titanate, ammonium fluoride and concentrated hydrochloric acid is 0.005-0.05:0.0055-0.055:0.001-0.01.

[0011] Furthermore, in step three, the hydrothermal reaction temperature is 100-300° C., and the reaction time is 20-50 h.

[0012] The invention provides a sub-nanometer titanium-based unit cell twisted gas diffusion electrode material. The material is a fluorine-doped titanium oxide electrode material having a titanium oxide octahedral unit cell twisted structure. The size of the material is 20-50 nm.

[0013] In addition, the present invention also provides a gas diffusion electrode based on the above electrode material, wherein the electrode material, the binder Nafion, and the conductive agent carbon black are uniformly dispersed with isopropanol to prepare a catalyst dispersion, which is then dripped onto a carbon substrate and dried naturally; and then assembled with a polytetrafluoroethylene film to form a gas diffusion electrode.

[0014] Finally, the present invention also provides a sub-nano titanium-based unit cell twisted gas diffusion electrode as a catalyst for electrocatalytic oxygen reduction to synthesize hydrogen peroxide in a strong acid or strong base electrolyte.

[0015] Compared with the prior art, the advantages of the present invention are as follows: (1) the electrode is composed of a sub-nanometer titanium-based unit cell twisted material to form an oxygen diffusion electrode, the preparation method is simple, and large-scale industrial production can be achieved; (2) the material is conducive to the exposure of more active sites and provides abundant active sites; (3) the tolerance to electrolytes with different pH values ​​is improved, eliminating the need for electrolyte acidity and alkali for electrocatalytic reduction under specific conditions; (4) the current density is close to the ampere level (1000mAcm) under the condition that the electrolyte pH is 1 to 13 -2 ) The Faraday efficiency of oxygen electrolysis to produce hydrogen peroxide can still be maintained at around 90%, which has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1(a) is a schematic diagram of the assembly of the sub-nanometer titanium-based unit cell twisted gas diffusion electrode of the present invention, Figure 1 (b) shows a real picture of the gas diffusion electrode assembled into an electrolytic cell.

[0017] Figure 2 These are TEM images of Example 1 of the present invention, wherein (a) is the overall morphology of particles of Example 1, (b) is a high-resolution TEM local image of Example 1, (c) is a partial lattice fringe image of Example 1, and (d) is a partial lattice fringe image of Example 1.

[0018] Figure 3 The present invention is the lattice distortion sites (a) marked in the high-resolution TEM image of Example 1, and the lattice site size measurement (b).

[0019] Figure 4 (a) is the full spectrum image of X-ray photoelectron spectroscopy (XPS) of Example 1 of the present invention and Comparative Example 1, (b) is the characteristic spectrum of Ti element 2p of Example 1 of the present invention and Comparative Example 1, (c) is the characteristic spectrum of O element 1s of Example 1 of the present invention and Comparative Example 1, and (d) is the characteristic spectrum of F1s element of Example 1 of the present invention.

[0020] Figure 5 (a) is the X-ray diffraction pattern (XRD) of Comparative Example 1 of the present invention, and (b) is the X-ray diffraction pattern (XRD) of Example 1 of the present invention.

[0021] Figure 6 (a) is the electron paramagnetic resonance spectrum (EPR) of Comparative Example 1 and Example 1 of the present invention, and (b) is the solid ultraviolet spectrum (Uv-Vis) of Comparative Example 1 and Example 1 of the present invention.

[0022] Figure 7 (a) is the CV polarization curve of the H-type electrolytic cell test in oxygen of Example 1 of the present invention and Comparative Example 1, and the inset shows the LSV polarization curve; (b) is the CV polarization curve of Example 1 in argon and oxygen, and the inset shows the LSV polarization curve.

[0023] Figure 8 It is the RRDE data diagram of comparative example 1 and example 1 of the present invention, selectivity (a) and the number of transferred electrons (b).

[0024] Fig. 9 The ultraviolet absorbance curve of the color-developed hydrogen peroxide in Comparative Example 1 of the present invention (a) shows that as the current density gradient increases, the potential / product concentration increases in a gradient manner. (b) shows the potential change of Example 1 in a constant current test at 100-1000 mA cm-2.

[0025] Fig.10(a) is the Faraday efficiency diagram (FE) of the full pH electrolyte of Comparative Example 1 of the present invention, and (b) is the Faraday efficiency diagram (FE) of the full pH electrolyte of Example 1 of the present invention.

[0026] Fig.11 The figure shows the stability test of the full pH electrolyte of Example 1 of the present invention.

[0027] Fig.12 (a) is a Faraday efficiency and yield diagram of the neutral electrolyte of comparative example 1 of the present invention, (b) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 2 of the present invention, (c) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 3 of the present invention, (d) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 4 of the present invention, (e) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 5 of the present invention, and (f) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 6 of the present invention.

[0028] Fig.13 (a) is the impedance diagram (EIS) of Example 2 of the present invention, (b) is the impedance diagram (EIS) of Example 3 of the present invention, (c) is the impedance diagram (EIS) of Example 1 of the present invention and Comparative Example 1, (d) is the impedance diagram (EIS) of Example 4 of the present invention, (e) is the impedance diagram (EIS) of Example 5 of the present invention, and (f) is the impedance diagram (EIS) of Example 6 of the present invention.

[0029] Fig.14 1 is a data graph of economic analysis of Example 1 of the present invention in oxygen, (a) is the cost of producing hydrogen peroxide in oxygen in Example 1 of the present invention and Comparative Example 1, (b) is the cost of producing hydrogen peroxide in oxygen in Example 1 of the present invention using electrolytes of different pH values, (c) is the cost proportion of Example 1 of the present invention in oxygen, (d) is the single factor analysis of Example 1 of the present invention in oxygen, and (e) is a comparative analysis of the cumulative net present value of producing hydrogen peroxide in oxygen in Example 1 of the present invention and Comparative Example 1.

[0030] Fig.15 It is a schematic diagram of the synthesis process and principle of the sub-nanometer titanium-based unit cell twisted gas diffusion electrode material of the present invention. DETAILED DESCRIPTION

[0031] Combination Fig.15 In order to improve the TiO 2 In order to improve the 2e-ORR performance of TiO, non-metallic elements such as P, S, and Se were first doped into it, but the performance did not improve significantly. Then, F was doped into it, and surprisingly, it was found that due to the strong electronegativity of F, TiO 2The Ti charge in the titanium oxide is plundered by the F element, resulting in an increase in the adsorption capacity of the Ti site for the intermediate OOH of the 2e-ORR, thereby increasing the 2e-ORR performance and making it resistant to acid and alkali. In addition, the doping of F causes the unit cell of the Ti-O octahedron to be distorted, further enhancing the acid and alkali resistance of the already stable titanium dioxide metal oxide.

[0032] The present invention is illustrated by the following examples, which are only used for illustration and cannot be regarded as limiting the scope of the invention or the application method of the invention. Unless otherwise specified, the raw materials of the present invention are commercially available.

[0033] Embodiment 1:

[0034] Step 1: Dissolve 411 mg of ammonium fluoride and 0.732 mL of concentrated hydrochloric acid in 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0035] Step 2: Add 1.517 mL of tetraisopropyl titanate to the mixed solution obtained in step 1 and stir for another 2 hours to form a uniform mixed solution;

[0036] Step 3: placing the solution obtained in step 2 in a sealed environment at 150° C. for reaction for 48 hours, and then centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material, the XPS quantitative analysis of which is shown in Table 1;

[0037] Step 4: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 3 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0038] Embodiment 2:

[0039] Step 1: Dissolve 137 mg of ammonium fluoride and 0.244 mL of concentrated hydrochloric acid in 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0040] Step 2: Add 1.517 mL of tetraisopropyl titanate to the mixed solution obtained in step 1 and stir for another 2 hours to form a uniform mixed solution;

[0041] Step 3: placing the solution obtained in step 2 in a sealed environment at 150° C. for 48 hours, and centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material;

[0042] Step 4: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 3 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0043] Embodiment 3:

[0044] Step 1: Dissolve 274 mg of ammonium fluoride and 0.488 mL of concentrated hydrochloric acid in 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0045] Step 2: Add 1.517 mL of tetraisopropyl titanate to the mixed solution obtained in step 1 and stir for another 2 hours to form a uniform mixed solution;

[0046] Step 3: placing the solution obtained in step 2 in a sealed environment at 150° C. for 48 hours, and centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material;

[0047] Step 4: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 3 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0048] Embodiment 4:

[0049] Step 1: Dissolve 548 mg of ammonium fluoride and 0.976 mL of concentrated hydrochloric acid in 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0050] Step 2: Add 1.517 mL of tetraisopropyl titanate to the mixed solution obtained in step 1 and stir for another 2 hours to form a uniform mixed solution;

[0051] Step 3: placing the solution obtained in step 2 in a sealed environment at 150° C. for 48 hours, and centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material;

[0052] Step 4: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 3 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0053] Embodiment 5:

[0054] Step 1: Dissolve 685 mg of ammonium fluoride and 1.22 mL of concentrated hydrochloric acid in 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0055] Step 2: Add 1.517 mL of tetraisopropyl titanate to the mixed solution obtained in step 1 and stir for another 2 hours to form a uniform mixed solution;

[0056] Step 3: placing the solution obtained in step 2 in a sealed environment at 150° C. for 48 hours, and centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material;

[0057] Step 4: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 3 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0058] Embodiment 6:

[0059] Step 1: Dissolve 822 mg of ammonium fluoride and 1.464 mL of concentrated hydrochloric acid in 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0060] Step 2: Add 1.517 mL of tetraisopropyl titanate to the mixed solution obtained in step 1 and stir for another 2 hours to form a uniform mixed solution;

[0061] Step 3: placing the solution obtained in step 2 in a sealed environment at 150° C. for 48 hours, and centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material;

[0062] Step 4: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 3 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0063] Comparative Example 1:

[0064] Step 1: Add 1.517 mL of tetraisopropyl titanate into 56 mL of ethanol and stir for 30 minutes to form a uniform mixed solution;

[0065] Step 2: The solution obtained in step 1 is placed in a sealed environment at 150° C. for reaction for 48 hours, and then centrifuged and freeze-dried to obtain a titanium-based gas diffusion electrode material, the XPS quantitative analysis of which is shown in Table 1;

[0066] Step 3: The sub-nano titanium-based unit cell twisted catalytic material obtained in step 2 is combined with Nafion, carbon black, carbon substrate, and polytetrafluoroethylene film to form a sub-nano titanium-based unit cell twisted gas diffusion electrode.

[0067] Table 1 is the atomic content of Example 1 and Comparative Example 1 analyzed by XPS quantitative analysis

[0068]

[0069] Figure 1 (a) is a schematic diagram of the assembly of the sub-nano titanium-based unit cell twisted gas diffusion electrode of the present invention. The catalyst material is loaded on the hydrophobic side of the carbon substrate to form a gas diffusion electrode, which is assembled into an electrolytic cell to become a cathode, and a cationic membrane is used to separate the cathode and the anode. Figure 1 (b) shows a real picture of the gas diffusion electrode assembled into an electrolytic cell.

[0070] The TEM image of Comparative Example 1 is as follows Figure 2 As shown in (a), the same as in Example 1 (( Figure 2 Compared with (b) in the figure, the overall morphology of the material has not changed significantly, and Example 1 basically retains the particle size of Comparative Example 1. When the material is further magnified, the high-resolution TEM ( Figure 2(c) shows that the nanoparticles have well-defined interplanar dimensions with a spacing of 0.234 nm, which corresponds to the (100) plane of TiOF2. Figure 2 The interplanar spacing of the nanoparticles shown in d is 0.273 nm, which corresponds to the (110) crystal plane of rutile phase TiO2.

[0071] In order to further determine the specific characteristics of doping in Example 1, we further magnified the high-resolution TEM image and found that the lattice fringes of the material in Example 1 had dislocation fractures. Figure 2 The local magnification of the lattice fringe distortion site in (c) is further observed. Figure 3 In (a), the two unit cell distortions are clearly marked and their dimensions are measured, such as Figure 3 (b) We found that the size of the unit cell distortion reached a sub-nanometer scale of about 0.2nm.

[0072] Figure 4 (a) The XPS measurement spectrum of Comparative Example 1 is mainly composed of Ti and O peaks, and the XPS measurement spectrum of Example 1 is mainly composed of Ti, F and O peaks. Figure 4 (b) O 1s XPS spectrum shows a main peak at 529.7, corresponding to the lattice oxygen (Ti-O) in Comparative Example 1. Interestingly, a small peak at 533.0 eV attributed to the surface hydroxyl group (Ti-OH) appears in Example 1. 2 O is filled by the reaction, so the oxygen vacancy induces the dissociation of water molecules and passes through H + Transfer to adjacent lattice oxygen to form two hydroxyl groups. Figure 4 The two peaks at 458.5 and 464.2 eV in (c) high-resolution Ti 2p XPS spectrum correspond to the Ti 2p 3 / 2 and Ti 2p 1 / 2 After F doping, Ti 2p 3 / 2 Peak and Ti 2p 1 / 2 The peak shifts to smaller bond energies, indicating the presence of Ti 3+ Species. Figure 4 (d) F-doped TiO 2 The F1s XPS spectrum after the reaction is decomposed into two peaks. The peak at 684.7 eV corresponds to the surface F ions. The peak at 686.1 eV is attributed to the substitutional F ions in the F-TiO2 lattice, which is consistent with the TiO 2 The reported values ​​for bulk F ions in the lattice are consistent.

[0073] In addition, according to the characteristic peaks of Ti, O and F in the XPS spectrum, we analyzed the element content of Example 1 and Comparative Example 1, and the atomic proportions of the elements are shown in Table 1. The F atoms in Example 1 indicate that F atoms have been successfully doped and replaced some O atoms to create oxygen vacancies. Combined with TEM and other data, it shows that the introduction of abundant F atoms in Example 1 causes lattice distortion without causing drastic changes in the crystal structure.

[0074] Figure 5 The crystal structures of Example 1 and Comparative Example 1 were further studied by X-ray diffraction analysis (XRD), and it was found that the positions of the peaks were different. By comparison, it was found that the number of crystal faces in Example 1 increased, and F doping caused significant changes in the crystal.

[0075] Figure 6 (a) shows the electron paramagnetic resonance spectrum information of Example 1 and Comparative Example 1. It can be clearly seen that the EPR signal of the material in Example 1 at g=2.003 is larger than that in Comparative Example 1, proving the existence of oxygen defects in Example 1. Figure 6 (b) shows the UV-visible absorption spectra of the prepared samples of Example 1 and Comparative Example 1. It can be clearly seen that Comparative Example 1 shows significantly enhanced light absorption in the visible light region, and the strong visible light absorption is attributed to the presence of oxygen vacancies, which can induce continuous donor energy levels of electronic states below the conduction band, which is the same as the conclusion drawn by XPS and EPR.

[0076] Figure 7 As shown in (a), the electrochemical performance of the ORR performance of the relevant material Example 1 is compared with that of the material of Comparative Example 1. Example 1 has a higher reduction potential, but the current density does not change significantly, indicating that the electrochemical active area of ​​the material of Example 1 is larger and has abundant active sites. This is because the F doping in the material of Example 1 induces oxygen vacancies to cause efficient utilization of ORR through oxygen polarization. And through Figure 3 From the small figure a, we can see that the reduction peaks of the materials of comparative example 1 and example 1 are both around 0.35 V, but the current density of example 1 is slightly larger than that of comparative example 1, which also shows that the electrochemical active area of ​​the material of example 1 is larger and has abundant active sites. Figure 7 In (b) of Figure 5, in an oxygen-saturated electrolyte, the CV curve has a reduction peak at 0.31 V vs. RHE. However, when the electrolyte is replaced with an argon-saturated electrolyte, the reduction peak disappears, indicating that under the corresponding voltage conditions, the oxygen in the electrolyte undergoes a reduction reaction. 2 and Ar 2The LSV comparison of the reactions under different conditions shows that there is a reduction peak at 0.35V vs. RHE in the oxygen-saturated electrolyte. This also shows that under the corresponding voltage conditions, the oxygen in the electrolyte undergoes a reduction reaction, and this reduction peak is the oxygen reduction peak.

[0077] Figure 8 In (a), the RRDE method shows that the selectivity of Example 1 in the voltage range of -0.2 to 0.2 V is about 80%, but the selectivity of Comparative Example 1 in the voltage range of -0.2 to 0.2 V drops sharply from 60% to 3%. This also proves that the two-electron oxygen reduction efficiency of Comparative Example 1 is much lower than that of Example 1. Figure 7 In (b), in the voltage range of -0.2 to 0.2 V, the number of electron transfers is about 2.3, which indicates that in the process of electrocatalytic oxygen reduction, the reaction process is more inclined to a two-electron reaction process. The number of transferred electrons in Comparative Example 1 is found to be about 3 in the voltage range of -0.2 to 0.2 V, which indicates that the oxygen reduction efficiency of Comparative Example 1 is much lower than that of Example 1 in the reaction potential range of -0.2 to 0.2 V.

[0078] Fig. 9 After the constant potential test in (a), the cathode electrolyte is taken out for color development reaction and UV test. The UV spectra of different materials show that the absorbance peak is at 408 nm. The material of Example 1 has the highest absorbance, that is, the hydrogen peroxide concentration in its corresponding electrolyte is the highest. Fig. 9 (b) is the chronoamperometric test (5min) of the material of Example 1 at different voltages and the chronoamperometric test of different materials at the same voltage. As the current density changes, the voltage also changes, which conforms to the general law of ORR. Within 5 minutes of the test, the voltage fluctuates in a small range, which is due to the disturbance caused by the continuous introduction of oxygen into the electrolyte to the electrochemical test system, which is a normal phenomenon. The current density in a large range remains basically stable, and no obvious attenuation occurs, so the test results have a stable reference value. When the current density is -1000mAcm -2 When , the hydrogen peroxide production is the highest, and the relationship between the hydrogen peroxide production rate and the current density of different materials is basically the same. For different materials, under all tested potentials, the material in Example 1 has the best performance.

[0079] Fig.10 (a) is a Faraday efficiency diagram of ORR test in comparative example 1 in electrolytes with different pH values, and the Faraday efficiency gradually decreases with increasing current. Fig.10(b) is the Faraday efficiency diagram of the ORR test in Example 1 in electrolytes with different pH values. It can be seen from the figure that the Faraday efficiency does not decay with the change of the pH value of the electrolyte and remains above 90%, which proves that the oxygen reduction performance of Example 1 is not affected by the change of the pH value of the electrolyte.

[0080] Fig.11 It is shown in the figure that Example 1 can continue to work stably for more than 50 hours in the long-term stability test.

[0081] Fig.12 (a) is a Faraday efficiency and yield diagram of Comparative Example 1 in a neutral electrolyte; (b) is a Faraday efficiency and yield diagram of Example 2 in a neutral electrolyte; (c) is a Faraday efficiency and yield diagram of Example 3 in a neutral electrolyte; (d) is a Faraday efficiency and yield diagram of Example 4 in a neutral electrolyte; (e) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 5; (f) is a Faraday efficiency and yield diagram of the neutral electrolyte of Example 6. As the current density increases, the Faraday efficiency performance decreases, indicating that Comparative Example 1, Example 2, Example 3 and Example 4 are not resistant to large currents.

[0082] Fig.13 (a) is the impedance graph (EIS) of Example 2; (b) is the impedance graph (EIS) of Example 3; (c) is the impedance graph (EIS) of Comparative Example 1 and Example 1; (d) is the impedance graph (EIS) of Example 4; (e) is the impedance graph (EIS) of Example 5; (f) is the impedance graph (EIS) of Example 6. Among them, the impedance of Example 4 is the largest at 150Ω, and the others are all around 50Ω.

[0083] Fig.14 The economic analysis of the production of hydrogen peroxide in oxygen by Example 1 is shown, wherein (a) shows a comparative analysis of the costs of producing hydrogen peroxide in oxygen by Example 1 and Comparative Example 1. The greater the current density, the lower the production cost of Example 1 in oxygen, and it is always lower than the production cost of the comparative example in oxygen; (b) is a comparative analysis of the costs of producing hydrogen peroxide in oxygen by different pH electrolytes of Example 1, and the cost of producing hydrogen peroxide does not increase significantly with the change of the pH of the electrolyte; (c) is the cost proportion of Example 1 in oxygen; (d) is a single factor analysis of Example 1 in oxygen; (e) shows the cumulative net present value analysis of the electrolysis in oxygen by Example 1 and Comparative Example 1. The data show that with the increase of time, the profit of Example 1 and Comparative Example 1 will gradually widen the gap, and the advantage of the electrolysis of Example 1 will become more prominent.

Claims

1. A method for preparing a sub-nanometer titanium-based unit cell twisted gas diffusion electrode material, It is characterized in that The following steps are involved: Step 1: dissolving ammonium fluoride and concentrated hydrochloric acid in ethanol and stirring to form a uniform mixed solution; Step 2: adding tetraisopropyl titanate to the mixed solution obtained in step 1 and stirring to form a uniform mixed solution; Step 3: placing the solution obtained in step 2 in a closed environment for hydrothermal reaction for a period of time, and then centrifugally freeze-drying to obtain a titanium-based gas diffusion electrode material.

2. The method according to claim 1, It is characterized in that The molar ratio of tetraisopropyl titanate, ammonium fluoride and concentrated hydrochloric acid is 0.005~0.05:0.0055~0.055:0.001~0.

01.

3. The method according to claim 1, It is characterized in that In step 3, the hydrothermal reaction temperature is 100-300 °C, and the reaction time is 20-50 h.

4. A sub-nano titanium-based unit cell distorted gas diffusion electrode material prepared by the method according to any one of claims 1 to 3.

5. The electrode material according to claim 4, It is characterized in that The electrode material is a fluorine-doped titanium oxide electrode material having a titanium oxide octahedral unit cell twisted structure, and the size of the electrode material is 20-50 nm.

6. A gas diffusion electrode based on the electrode material according to claim 4 or 5, It is characterized in that The electrode material, the binder Nafion, and the conductive agent carbon black are uniformly dispersed with isopropanol, and then dripped onto a carbon substrate and dried naturally; and then assembled with a polytetrafluoroethylene film to form a gas diffusion electrode.

7. Use of the gas diffusion electrode as claimed in claim 6 as a catalyst for synthesizing hydrogen peroxide by electrocatalytic reduction of oxygen in a strong acid or strong base electrolyte.

8. An oxygen electrolysis cell, It is characterized in that It comprises the gas diffusion electrode as claimed in claim 6.

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