Metal mixed titanium oxide catalyst as well as preparation method and application thereof

Abstract

The invention discloses a metal mixed titanium oxide catalyst as well as a preparation method and application thereof, and belongs to the technical field of electrochemical catalysis. The metal in the metal mixed titanium oxide catalyst is vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium or tin, and each element in the metal mixed titanium oxide catalyst exists in the form of a single titanium oxide lattice or a bimetal mixed oxide. The invention also discloses a preparation method and application of the metal mixed titanium oxide catalyst. The metal mixed titanium oxide catalyst is simple and convenient in preparation process and high in repeatability, metal atoms in a proper proportion are introduced into the titanium oxide, and then the crystal phase of the metal mixed titanium oxide is regulated and controlled through temperature; the adsorption capacity of the catalyst and carbonate in an electrolyte interface and the reaction activity of catalyzing the carbonate to be converted into a percarbonate intermediate are greatly enhanced, the selectivity and yield of H2O2 are remarkably improved, and efficient and green synthesis of H2O2 can be achieved without additionally introducing gas.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical catalysis, and specifically relates to a metal mixed titanium oxide catalyst and a preparation method and application thereof. Background Art

[0002] In the current industrial field, the production of hydrogen peroxide (H2O2) mainly relies on the traditional anthraquinone redox method. However, this method not only consumes a lot of energy, but is also not very environmentally friendly. What is more serious is that high concentrations of H2O2 pose potential safety risks during transportation. In view of these challenges, the on-site synthesis technology of H2O2 has become a major research focus in the field of scientific research.

[0003] Although cathode oxygen reduction technology has made some progress in the field of electrochemistry, it still relies on a continuous supply of oxygen and the support of gas diffusion electrodes in actual operation, which undoubtedly limits its wider application. - The WOR) pathway exhibits unique advantages: it uses water as the only reactant and does not require the participation of any gas, thus simplifying the reaction process and improving safety.

[0004] However, the key to achieving high yield and high selectivity of this pathway lies in finding suitable catalysts and electrolytes. These materials must be able to effectively convert water into H2O2 through a two-electron oxidation process. For metal oxide catalysts, differences in doping elements, crystal phases or heterogeneous structures will affect their interactions with reaction intermediates; and differences in electrolytes will affect the catalytic reaction mechanism and pathway, and these two will have a combined impact on the selectivity and yield of H2O2. How to accurately select and optimize these catalysts and electrolytes is still a technical problem that needs to be solved urgently. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a metal mixed titanium oxide catalyst and a preparation method and application thereof, so as to solve the problems of low selectivity and low yield in the existing electrocatalytic preparation of hydrogen peroxide.

[0006] The technical solution adopted to solve the technical problem is to provide a metal mixed titanium oxide catalyst, in which the metal is vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium or tin; each element in the metal mixed titanium oxide catalyst exists in the form of a single titanium oxide lattice or a bimetallic mixed oxide.

[0007] The beneficial effects of the above technical solution of the present invention are as follows: by introducing metal elements such as vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium or tin into titanium oxide in the form of a single titanium oxide lattice or a bimetallic mixed oxide, a unique crystal phase structure can be formed, and these crystal phase structures can change the electronic structure and surface properties of titanium oxide, thereby facilitating the generation of hydrogen peroxide; at the same time, the specific crystal phase structure is conducive to the adsorption of reactants and the desorption of products, thereby improving the catalytic efficiency, so that the catalyst has a higher selectivity for the generation of hydrogen peroxide.

[0008] Preferably, the metal in the metal mixed titanium oxide catalyst is chromium or manganese.

[0009] The present invention also provides a method for preparing the above metal mixed titanium oxide catalyst, comprising the following steps:

[0010] (1) dissolving a titanium source and a metal salt in alcohol respectively and then mixing them evenly to obtain a mixed solution;

[0011] (2) adding acid and water to the mixed solution and reacting at 50-150° C. for 12-24 hours to obtain a dry gel;

[0012] (3) Drying and calcining the dry gel to obtain a product.

[0013] Preferably, the titanium source is tetrabutyl titanate, isopropyl titanate or titanium tetrachloride; the metal salt is manganese nitrate, manganese chloride, manganese acetylacetonate, manganese acetate, chromium nitrate nonahydrate, chromium chloride, chromium acetylacetonate, zinc nitrate, zinc chloride or zinc acetylacetonate; and the acid is hydrochloric acid, acetic acid or oxalic acid.

[0014] Preferably, the molar ratio of the metal salt to the titanium source is 1:100 to 3:2.

[0015] More preferably, the reaction temperature in step (2) is 70-75° C. and the reaction time is 24 h.

[0016] Preferably, in step (3), the calcination temperature is 200 to 900° C. and the calcination time is 1 to 12 hours.

[0017] More preferably, in step (3), the calcination temperature is 400-700° C. and the calcination time is 3-4 hours.

[0018] The present invention also provides the use of the metal mixed titanium oxide catalyst in preparing hydrogen peroxide by electrocatalytic water oxidation.

[0019] Preferably, the use of a metal mixed titanium oxide catalyst in the electrocatalytic oxidation of water to prepare hydrogen peroxide comprises the following steps:

[0020] A metal mixed titanium oxide catalyst is loaded on a conductive substrate to obtain a working electrode; a saturated calomel electrode is used as a reference electrode, a carbon rod is used as a counter electrode, and a Nafion membrane is used as an ion exchange membrane to prepare hydrogen peroxide in an electrolyte.

[0021] Preferably, the conductive substrate is carbon fiber paper, titanium sheet, titanium felt or fluorine antimony tin oxide; and the electrolyte is a mixed solution of carbonate and bicarbonate.

[0022] The beneficial effects of the technical solution adopted in the present invention are as follows: in the process of electrocatalytically generating H2O2, the carbonate in the electrolyte first needs to be oxidized and adsorbed onto the catalyst surface, and then further coupled with the carbonate in the electrolyte to be oxidized into percarbonate, the percarbonate will desorb, and spontaneously hydrolyze in the electrolyte to generate H2O2 and bicarbonate, and finally the bicarbonate will be recycled back to carbonate ions through the carbonate / bicarbonate equilibrium reaction; in the absence of carbonate, whether in a neutral system or a strongly alkaline system, the selectivity of H2O2 is very low, and only in a carbonate / bicarbonate system is the selectivity of H2O2 partially improved; at the same time, the pH in a single carbonate electrolyte system is relatively high, generally above 12, which leads to OH in the solution. - Due to the large presence of *OH, more *OH will be adsorbed on the catalyst surface, thereby driving the OER reaction and affecting the H2O2 selectivity. The introduction of an appropriate amount of bicarbonate can effectively reduce the pH of the electrolyte system. At the same time, the pH of the system can be stabilized through the equilibrium reaction of carbonate / bicarbonate during the electrolysis process, so that the selectivity can be optimized.

[0023] Preferably, the concentration of the electrolyte is 1 to 5 mol / L.

[0024] Preferably, the molar ratio of carbonate to bicarbonate in the electrolyte is 0.5:3.5 to 3.5:0.5.

[0025] The present invention has the following beneficial effects:

[0026] The preparation process of the metal mixed titanium oxide catalyst of the present invention is simple and reproducible. By introducing an appropriate proportion of metal atoms into titanium oxide and then regulating the crystal phase of the metal mixed titanium oxide by temperature, the adsorption capacity of carbonate at the interface between the catalyst and the electrolyte and the reaction activity of catalyzing the conversion of carbonate into an important intermediate (percarbonate) are greatly enhanced, thereby significantly improving the selectivity and yield of H2O2. On this basis, by matching the interface between different metal mixed titanium oxide catalysts and the electrolyte, the ratio of carbonate to bicarbonate in the electrolyte system can be flexibly adjusted, and the 2e -The WOR reaction pathway further improves the yield and selectivity of H2O2; the entire electrolysis process relies only on water as a single reactant, and efficient and green synthesis of H2O2 can be achieved without the introduction of additional gas; the present invention not only simplifies the production process of the catalyst, but also greatly reduces the production cost and potential safety risks, opening up a novel and efficient way for the on-site preparation of H2O2 in the industrial sector. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the X-ray diffraction pattern of the metal mixed titanium oxide catalyst of Example 1;

[0028] Figure 2 is a transmission electron microscope image of the metal mixed titanium oxide catalyst of Example 1;

[0029] Figure 3 is the energy dispersive X-ray spectrum of the metal mixed titanium oxide catalyst of Example 1;

[0030] Figure 4 is the X-ray diffraction pattern of the metal mixed titanium oxide catalyst of Example 2;

[0031] Figure 5 is a transmission electron microscope image of the metal mixed titanium oxide catalyst of Example 2;

[0032] Figure 6 is the energy dispersive X-ray spectrum of the metal mixed titanium oxide catalyst of Example 2;

[0033] Figure 7 is the linear sweep voltammogram of the working electrode in Example 3;

[0034] Figure 8 is a selectivity curve diagram of the working electrode at different voltages in Example 3;

[0035] Fig. 9 This is a graph showing the yield of the working electrode at different voltages in Example 3;

[0036] Fig.10 is the linear sweep voltammogram of the working electrode in Example 4;

[0037] Fig.11 is a selectivity curve diagram of the working electrode at different voltages in Example 4;

[0038] Fig.12 This is a graph showing the yield of the working electrode at different voltages in Example 4;

[0039] Fig.13 is the X-ray diffraction pattern of the titanium oxide catalyst of Comparative Example 1;

[0040] Fig.14is the X-ray diffraction pattern of the titanium oxide catalyst of Comparative Example 2;

[0041] Fig.15 Carbonate mediated 2e - Schematic diagram of the WOR reaction mechanism;

[0042] Fig.16 The in-situ infrared test results at different voltages are shown;

[0043] Fig.17 The selectivity curve of rutile phase manganese mixed titanium oxide catalyst in different electrolyte systems;

[0044] Fig.18 This is a selectivity curve diagram of the working electrode of the metal mixed titanium oxide catalyst in Example 1 in different electrolyte systems;

[0045] Fig.19 This is a selectivity curve diagram of the working electrode of the metal mixed titanium oxide catalyst in different electrolyte systems of Example 2;

[0046] Fig. 20 This is a selectivity curve diagram of the working electrode of the titanium oxide catalyst in Comparative Example 1 in different electrolyte systems;

[0047] Fig.21 This is the selectivity curve diagram of the working electrode of the titanium oxide catalyst of Comparative Example 2 in different electrolyte systems. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0049] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0050] The features and performance of the present invention are further described in detail below in conjunction with embodiments.

[0051] Example 1

[0052] A metal mixed titanium oxide catalyst, wherein the metal in the metal mixed titanium oxide catalyst is manganese; the metal mixed titanium oxide catalyst is anatase titanium dioxide phase.

[0053] This embodiment also provides a method for preparing the above metal mixed titanium oxide catalyst, comprising the following steps:

[0054] (1) Weigh 1 mL of tetrabutyl titanate and add it dropwise into 3 mL of ethanol to obtain solution A;

[0055] (2) Weigh 0.03 g of anhydrous manganese chloride and dissolve it in 4 mL of ethanol to obtain solution B;

[0056] (3) adding solution B to solution A and mixing evenly to obtain a mixed solution;

[0057] (4) Add 1 mL of acetic acid and 1 mL of water to the mixed solution, mix well, and react in an oil bath at 75 °C for 24 h to obtain a dry gel;

[0058] (5) The dry gel was placed in an oven at 70°C for overnight drying and then taken out and placed in a porcelain boat. The porcelain boat was then placed in a tubular furnace and calcined at 400°C for 3 hours in an air atmosphere to obtain the dry gel.

[0059] The metal mixed titanium oxide catalyst obtained in this example was subjected to X-ray diffraction, transmission electron microscopy and EDS analysis. The results are as follows: Figures 1 to 3 As shown. Figure 1 It can be seen from the figure that the metal mixed titanium oxide catalyst obtained in this example is anatase titanium dioxide phase without other diffraction peaks; Figure 2 It can be seen that the metal mixed titanium oxide catalyst obtained in this example has an irregular nanoparticle morphology with a particle size of 10 to 20 nm; manganese atoms account for 8% and titanium atoms account for 92% ( Figure 3 ).

[0060] Example 2

[0061] A metal mixed titanium oxide catalyst, wherein the metal in the metal mixed titanium oxide catalyst is chromium; the metal mixed titanium oxide catalyst is a heterogeneous mixed phase of rutile titanium dioxide and chromite chromium trioxide.

[0062] This embodiment also provides a method for preparing the above metal mixed titanium oxide catalyst, comprising the following steps:

[0063] (1) Weigh 1 mL of tetrabutyl titanate and add it dropwise into 3 mL of ethanol to obtain solution A;

[0064] (2) Weigh 1.12 g of chromium nitrate nonahydrate and dissolve it in 4 mL of ethanol to obtain solution B;

[0065] (3) adding solution B to solution A and mixing evenly to obtain a mixed solution;

[0066] (4) Add 1 mL of acetic acid and 1 mL of water to the mixed solution, mix well, and react in an oil bath at 70 °C for 24 h to obtain a dry gel;

[0067] (5) The dry gel was placed in an oven at 70°C for drying overnight, then taken out and placed in a porcelain boat. The porcelain boat was then placed in a tubular furnace and calcined at 700°C for 4 hours in an air atmosphere to obtain the dry gel.

[0068] The metal mixed titanium oxide catalyst obtained in this example was subjected to X-ray diffraction, transmission electron microscopy and EDS analysis. The results are as follows: Figures 4 to 6 As shown. Figure 4 It can be seen from the figure that the metal mixed titanium oxide catalyst obtained in this example is a heterogeneous mixed phase of rutile titanium dioxide and chromite chromium trioxide, without other diffraction peaks; Figure 5 It can be seen that the metal mixed titanium oxide catalyst obtained in this example has the morphology of irregular nanoparticles with a particle size between 50 and 150 nm; the chromium atoms account for 40% and the titanium atoms account for 60% ( Figure 6 ).

[0069] Example 3

[0070] The application of a metal mixed titanium oxide catalyst in the electrocatalytic oxidation of water to prepare hydrogen peroxide comprises the following steps:

[0071] (1) The metal mixed titanium oxide catalyst obtained in Example 1 was ground in a mortar, and after grinding, 5 mg of the metal mixed titanium oxide catalyst was weighed and added to a mixed solution of 0.5 mL of isopropanol, 0.5 mL of water and 20 μL of Nafion, and the catalyst slurry was obtained after ultrasonic dispersion;

[0072] (2) Evenly apply the catalyst slurry on the carbon fiber paper 1 cm thick. 2 In the area of ​​, the working electrode is obtained;

[0073] (3) In the electrocatalytic system, the anode region and the cathode region are separated by an ion exchange membrane, which is a Nafion membrane; the reference electrode is a saturated calomel electrode, the counter electrode is a carbon rod, the working electrode is the working electrode obtained in step (2), and the electrolyte is a mixed solution of potassium carbonate and potassium bicarbonate with a concentration of 4 mol / L, wherein the molar ratio of potassium carbonate to potassium bicarbonate is 3:1, and hydrogen peroxide is prepared.

[0074] The electrochemical test was carried out by the H-type test system, and the results were as follows Figures 7 to 9 As shown. Figure 7 It can be seen from the linear sweep voltammetry curve that when the current density reaches 10 mA cm -2When the onset potential is about 2.0 V, it means that the electrode is inert to oxygen evolution reaction, and in this electrolyte system, the current density can reach up to 320 mA cm -2 ; Different potentials of 2.1 to 2.7 V were applied by an electrochemical workstation to test the changes in the electrode selectivity and yield at different voltages. The results are as follows Figures 8-9 As shown, when the applied potential is 2.6 V, the working electrode is at 2e - The selectivity of WOR to produce H2O2 reached the highest level, up to 56%; the maximum H2O2 yield per square centimeter of electrode was 49.3 μmol cm -2 min -1 .

[0075] Example 4

[0076] The application of a metal mixed titanium oxide catalyst in the electrocatalytic oxidation of water to prepare hydrogen peroxide comprises the following steps:

[0077] (1) The metal mixed titanium oxide catalyst obtained in Example 2 was ground in a mortar, and after grinding, 5 mg of the metal mixed titanium oxide catalyst was weighed and added to a mixed solution of 0.5 mL of isopropanol, 0.5 mL of water and 20 μL of Nafion, and the catalyst slurry was obtained after ultrasonic dispersion;

[0078] (2) Evenly apply the catalyst slurry on the carbon fiber paper 1 cm thick. 2 In the area of ​​, the working electrode is obtained;

[0079] (3) In the electrocatalytic system, the anode region and the cathode region are separated by an ion exchange membrane, which is a Nafion membrane; the reference electrode is a saturated calomel electrode, the counter electrode is a carbon rod, the working electrode is the working electrode obtained in step (2), and the electrolyte is a mixed solution of potassium carbonate and potassium bicarbonate with a concentration of 4 mol / L, wherein the molar ratio of potassium carbonate to potassium bicarbonate is 2:2, and hydrogen peroxide is prepared.

[0080] The electrochemical test was carried out by the H-type test system, and the results were as follows Figures 10-12 As shown. Fig.10 The linear sweep voltammetry curve shows that the current density reaches 10 mA cm -2 When the onset potential is about 1.95 V, it means that the electrode is inert to oxygen evolution reaction, and in this electrolyte system, the current density can reach up to 350 mA cm -2 ; Different potentials of 2.1 to 2.7 V were applied by an electrochemical workstation to test the changes in the electrode selectivity and yield at different voltages. The results are as follows Figures 11-12 As shown in the figure, in a 2:2 mixed solution of potassium carbonate and potassium bicarbonate, when the applied potential is 2.6V, the working electrode is at 2e -The selectivity of WOR to produce H2O2 reached up to 71%, and the H2O2 yield per square centimeter of electrode reached up to 62.9 μmol cm -2 min -1 .

[0081] Comparative Example 1

[0082] A titanium oxide catalyst is in anatase phase.

[0083] This comparative example also provides a method for preparing the titanium oxide catalyst, comprising the following steps:

[0084] (1) Weigh 1 mL of tetrabutyl titanate and add it dropwise into 3 mL of ethanol to obtain solution A;

[0085] (2) Add 4 mL of ethanol to solution A to obtain solution B;

[0086] (3) Add 1 mL of acetic acid and 1 mL of water to solution B, mix well, and react in an oil bath at 70 °C for 24 h to obtain a dry gel;

[0087] (5) The dry gel was placed in an oven at 70°C for overnight drying and then taken out and placed in a porcelain boat. The porcelain boat was then placed in a tubular furnace and calcined at 400°C for 3 hours in an air atmosphere to obtain the dry gel.

[0088] The titanium oxide catalyst obtained in this comparative example was subjected to X-ray diffraction analysis, and the results were as follows: Fig.13 As shown. Fig.13 It can be seen that the titanium oxide catalyst obtained in this comparative example is anatase phase without other diffraction peaks.

[0089] Comparative Example 2

[0090] A titanium oxide catalyst is in rutile phase.

[0091] This comparative example also provides a method for preparing the titanium oxide catalyst. The difference from comparative example 1 is that the calcination temperature in step (5) is 900° C. and the calcination time is 3 h; the remaining steps and parameters are the same as those in comparative example 1.

[0092] The titanium oxide catalyst obtained in this comparative example was subjected to X-ray diffraction analysis, and the results were as follows: Fig.14 As shown. Fig.14 It can be seen that the titanium oxide catalyst obtained in this comparative example is in rutile phase and has no other diffraction peaks.

[0093] Comparative Example 3

[0094] A metal mixed titanium oxide catalyst, wherein the metal in the metal mixed titanium oxide catalyst is manganese; the metal mixed titanium oxide catalyst is a rutile titanium dioxide phase.

[0095] This comparative example also provides a method for preparing the metal mixed titanium oxide catalyst. The difference from Example 1 is that the calcination temperature in step (5) is 800° C. and the calcination time is 3 h; the remaining steps and parameters are the same as those in Example 1.

[0096] Experimental example

[0097] 1. Strategic analysis of catalyst and electrolyte regulation and matching

[0098] Preparation of electrolytes with different molar ratios: Under dry conditions, potassium carbonate and potassium bicarbonate were weighed in order according to the molar ratios of 0:4, 0.5:3.5, 1:3, 2:2, 3:1, 3.5:0.5 and 4:0, the potassium carbonate and potassium bicarbonate were quickly mixed and dissolved in 500 mL of deionized water, and the mixture was sealed and stirred for 12 h for use.

[0099] According to the steps of Example 3, the catalysts obtained in Examples 1 to 2 and Comparative Examples 1 to 3 were prepared as working electrodes, and electrochemical tests were carried out in electrolyte systems with different molar ratios using an H-type test system. The electrocatalytic reaction mechanism and analysis are as follows: Figures 15 to 17 The test results are shown in Figures 18 to 21 .from Fig.15 It can be seen that in the process of electrocatalytic production of hydrogen peroxide, carbonate in the electrolyte first needs to be oxidized and adsorbed to the catalyst surface, and then further coupled with carbonate in the electrolyte to be oxidized to percarbonate. Percarbonate will desorb and spontaneously hydrolyze in the electrolyte to generate H2O2 and bicarbonate, and finally bicarbonate will be recycled back to carbonate ions through the carbonate / bicarbonate equilibrium reaction; in this cycle, carbonate only plays a mediating role, and water is a consumed reactant. This mechanism has been proven to be reasonable by in situ infrared tests at different potentials on the electrode surface ( Fig.16 As shown in Figure 3, with the increase of voltage, the consumption of carbonate near the electrode, the accumulation of bicarbonate and the presence of important intermediate percarbonate were detected. In addition, 2e - The mechanism-assisted analysis of WOR is provided by Fig.17The results show that in the absence of carbonate, the selectivity of hydrogen peroxide is very low in both neutral and strongly alkaline systems, and only in carbonate / bicarbonate systems is the selectivity of hydrogen peroxide partially improved; it can be seen that if the catalyst surface adsorbs water molecules or *OH in the electrolyte system, it will eventually drive four-electron water oxidation, that is, oxygen evolution reaction, and only when carbonate is adsorbed will the carbonate-mediated pathway be used to produce hydrogen peroxide. Based on this phenomenon and mechanism, it can be concluded that there are three factors affecting the selectivity of hydrogen peroxide. The first is the concentration of carbonate. As a reactant, the higher the concentration of carbonate, the better the selectivity. Different metal mixed titanium oxide catalysts have different surface and electrolyte concentrations. The forces of electrolyte ions at the electrolyte interface are different, so different catalysts have different effects on this factor; the second is the concentration of bicarbonate. As a product of the hydrolysis of percarbonate, the lower the concentration of bicarbonate, the more the reaction tends to produce hydrogen peroxide. Therefore, the lower the concentration of bicarbonate, the higher the selectivity of hydrogen peroxide; the third is the pH value of the carbonate / bicarbonate buffer solution. The pH value is directly related to the carbonate / bicarbonate ratio. Although the carbonate-mediated mechanism seems to point to the result that the system using only carbonate will have the highest Faraday efficiency, the pH in the electrolyte system of pure carbonate is relatively high, generally above 12, which leads to OH in the solution. - With the presence of a large amount of *OH, more *OH will be adsorbed on the catalyst surface, thereby driving the OER reaction and affecting the selectivity of H2O2. The introduction of an appropriate amount of bicarbonate can effectively reduce the pH of the electrolyte system. At the same time, during the electrolysis process, the pH of the system is stabilized through the equilibrium reaction of carbonate / bicarbonate to achieve the best selectivity. In this reaction process, the reactant is still water in essence, and the electrolyte ions only play a mediating role. Therefore, finding the best ratio is meaningful and crucial for the production and application of H2O2. Fig.18 It can be seen that the working electrode obtained by the metal mixed titanium oxide catalyst of Example 1 has a very poor performance in the carbonate-free electrolyte system, while its selectivity for producing H2O2 in the carbonate / bicarbonate electrolyte system is significantly improved, and can be regulated and optimized by the ratio of the electrolyte, and its selectivity for producing H2O2 is the highest at a molar ratio of 3:1; while the working electrode obtained by the metal mixed titanium oxide catalyst of Example 2 has a very poor performance in the carbonate-free electrolyte system, while its selectivity for producing H2O2 in the carbonate / bicarbonate electrolyte system is significantly improved, and can be regulated and optimized by the ratio of the electrolyte, and its selectivity for producing H2O2 has reached the highest at a molar ratio of 2:2 ( Fig.19 ).from Figures 20-21It can be seen that different proportions of electrolyte can still improve the selectivity of H2O2 production, but the selectivity of the working electrode obtained by the anatase-type titanium oxide catalyst in Comparative Example 1 can only reach 19% at most, and the selectivity of the working electrode obtained by the rutile-type titanium oxide catalyst in Comparative Example 2 can only reach 15% at most. Therefore, the electrode obtained in Comparative Examples 1-2 has poor effect, and the selectivity and yield of H2O2 production are much lower than those of the catalyst in the embodiment of the present invention.

[0100] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the scope of the present invention.

Claims

1. A metal mixed titanium oxide catalyst, characterized in that: The metal in the metal mixed titanium oxide catalyst is vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium or tin; each element in the metal mixed titanium oxide catalyst exists in the form of a single titanium oxide lattice or a bimetallic mixed oxide.

2. The method for preparing the metal mixed titanium oxide catalyst according to claim 1, characterized in that: The following steps are involved: (1) dissolving a titanium source and a metal salt in alcohol respectively and then mixing them evenly to obtain a mixed solution; (2) adding acid and water to the mixed solution and reacting at 50-150° C. for 12-24 hours to obtain a dry gel; (3) Drying and calcining the dry gel to obtain a product.

3. The method for preparing a metal mixed titanium oxide catalyst according to claim 2, characterized in that: The titanium source is tetrabutyl titanate, isopropyl titanate or titanium tetrachloride; the metal salt is manganese nitrate, manganese chloride, manganese acetylacetonate, manganese acetate, chromium nitrate nonahydrate, chromium chloride, chromium acetylacetonate, zinc nitrate, zinc chloride or zinc acetylacetonate; and the acid is hydrochloric acid, acetic acid or oxalic acid.

4. The method for preparing a metal mixed titanium oxide catalyst according to claim 2, characterized in that: The element molar ratio of the metal salt to the titanium source is 1:100 to 3:

2.

5. The method for preparing the metal mixed titanium oxide catalyst according to claim 2, characterized in that: In the step (3), the calcination temperature is 200 to 900° C. and the calcination time is 1 to 12 hours.

6. Use of the metal mixed titanium oxide catalyst according to claim 1 in preparing hydrogen peroxide by electrocatalytic water oxidation.

7. The use according to claim 6, characterized in that The following steps are involved: The metal mixed titanium oxide catalyst is loaded on a conductive substrate to obtain a working electrode; Hydrogen peroxide was prepared in an electrolyte using a saturated calomel electrode as a reference electrode, a carbon rod as a counter electrode, and a Nafion membrane as an ion exchange membrane.

8. The use according to claim 7, characterized in that The conductive substrate is carbon fiber paper, titanium sheet, titanium felt or fluorine antimony tin oxide; the electrolyte is a mixed solution of carbonate and bicarbonate.

9. The use according to claim 7 or 8, characterized in that The concentration of the electrolyte is 1-5 mol / L.

10. The use according to claim 7 or 8, characterized in that: The molar ratio of carbonate to bicarbonate in the electrolyte is 0.5:3.5 to 3.5:0.5.

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