Titanium carbide and carbon composite material, preparation method and application thereof, double-PEM reaction galvanic pile and application of double-PEM reaction galvanic pile
By preparing titanium carbide@carbon composite materials and dual PEM reaction stacks, the problems of hydrogen peroxide decomposition and anion membrane instability in alkaline solutions were solved, and efficient and stable hydrogen peroxide electrical synthesis within the full pH range were achieved.
Patent Information
- Application Number
- CN202510587294.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2025-08-08
AI Technical Summary
In the prior art, the decomposition of hydrogen peroxide in alkaline solutions is easy to occur, and the anion exchange membrane is not as stable as the proton exchange membrane, making it difficult to achieve efficient and stable electrical synthesis of hydrogen peroxide.
The titanium carbide @ carbon composite material was used as the electrode, and prepared by hydrothermal-sintering method, combined with a dual proton exchange membrane reaction stack, three chambers separated by double PEM membranes were constructed to achieve the electrosynthesis of hydrogen peroxide in the full pH range.
The activity and selectivity of the two electron oxygen reduction reaction is significantly improved, the charge transfer resistance is reduced, the catalyst life is extended, and the stable generation of hydrogen peroxide is achieved within the entire pH range.
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Figure CN120443241A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of hydrogen peroxide synthesis, and in particular to a titanium carbide@carbon composite material, a preparation method and application thereof, and a dual PEM reactor stack and application thereof. Background Art
[0002] Hydrogen peroxide (H2O2) is an important green industrial oxidant. The two-electron oxygen reduction reaction (2e - ORR) represents a promising new process for sustainable H2O2 production. For industrial applications, low-cost materials (such as carbon-based catalysts) are used in alkaline solutions at high current densities to achieve small overpotentials and high 2e - ORR is relatively easy to select for H2O2. However, in alkaline solution, H2O2 is deprotonated (pKa = 11.75) and is extremely easy to decompose. In addition, for double membrane electrode assembly (MEA) solid electrolyte (SE) electrolyzers, this type of material needs to be applied on anion exchange membrane (AEM), but unfortunately, anion exchange membrane (AEM) is usually not as stable as proton exchange membrane (PEM). Therefore, in order to realize the practical deployment of large-scale on-site production of H2O2, it is of great significance to develop and optimize a cheap, selective and stable catalyst to achieve an electrochemical reactor that efficiently promotes the continuous electrosynthesis of H2O2. Summary of the Invention
[0003] The purpose of the present invention is to provide a titanium carbide @ carbon composite material and its preparation method and application, dual PEM reactor and application. On the one hand, the titanium carbide @ carbon composite material is used for 2e - ORR generates H2O2 with good activity and selectivity for the two-electron oxygen reduction reaction; on the other hand, the dual-PEM reactor can electrosynthesize hydrogen peroxide over the entire pH range.
[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0005] The present invention provides a method for preparing a titanium carbide@carbon composite material, comprising the following steps:
[0006] The titanium carbide and the sugar precursor aqueous solution are mixed with acid, and a hydrothermal reaction is carried out at a pH of 4 to 6 to obtain a composite;
[0007] The composite is calcined in a protective atmosphere to obtain a titanium carbide@carbon composite material.
[0008] Preferably, the particle size of the titanium carbide is 10 to 100 nm; the sugar precursor in the sugar precursor aqueous solution includes one or more of glucose, sucrose and fructose; the concentration of the sugar precursor aqueous solution is 0.01 to 1 mol / L; and the dosage ratio of the titanium carbide to the sugar precursor aqueous solution is 0.5 g:18 to 38 mL.
[0009] Preferably, the acid comprises any one of citric acid, acetic acid, phosphoric acid, hydrochloric acid and sulfuric acid; the temperature of the hydrothermal reaction is 120-200° C., and the time is 6-24 hours.
[0010] Preferably, the protective atmosphere is nitrogen or argon; the calcination temperature is 400-800° C., the heating rate to the calcination temperature is 1-5° C. / min, and the calcination time is 0.5-3 h.
[0011] The present invention provides a titanium carbide@carbon composite material prepared by the preparation method described in the above technical solution.
[0012] The present invention provides the use of the titanium carbide@carbon composite material described in the above technical solution in an electric reactor for electrosynthesis of hydrogen peroxide.
[0013] The present invention provides a dual-PEM reactor stack, which is composed of an anode chamber, a first proton exchange membrane, a solid electrolyte layer, a second proton exchange membrane and a cathode chamber arranged in sequence;
[0014] The anode chamber contains an anode electrode, and the anode liquid is pure water; the anode electrode is a gas diffusion electrode coated with iridium oxide;
[0015] The cathode chamber contains a cathode electrode, and the cathode liquid is an alkali metal cation solution; the cathode electrode is a porous carbon fiber felt coated with the titanium carbide@carbon composite material described in the above technical solution.
[0016] Preferably, the preparation method of the cathode electrode comprises the following steps: mixing titanium carbide @ carbon composite material, alcohol, ionomer and water to obtain a dispersion, spraying the dispersion on the surface of porous carbon fiber felt to obtain a cathode electrode; the ionomer is a polytetrafluoroethylene solution with a mass fraction of 5 to 60%; the alcohol includes any one of methanol, ethanol, isopropanol and n-propanol; the loading amount of the titanium carbide @ carbon composite material on the porous carbon fiber felt is 1.0 to 5.0 mg / cm 2 .
[0017] Preferably, the alkali metal cations in the alkali metal cation solution include one or more of sodium ions, potassium ions, magnesium ions, calcium ions and lithium ions; the first proton exchange membrane and the second proton exchange membrane are independently one of N117, N115, and N212; the first proton exchange membrane and the second proton exchange membrane are attached to the surfaces of both sides of the substrate, and the cavity inside the substrate is filled with solid electrolyte.
[0018] The present invention provides the use of the dual PEM reactor described in the above technical solution in the electrosynthesis of hydrogen peroxide over the entire pH range.
[0019] The present invention provides a method for preparing a titanium carbide@carbon composite material, comprising uniformly mixing titanium carbide powder and a sugar precursor aqueous solution with an acid, performing a hydrothermal treatment, and calcining the resulting product under a protective atmosphere to obtain a titanium carbide@carbon composite material. The present invention uses titanium carbide with high electrical conductivity as a carrier and coats it with a highly active carbon layer. The titanium carbide@carbon composite material has both the metallic conductivity of titanium carbide and the oxygen-containing functional groups and defect sites on the surface of the carbon layer, significantly accelerating the transfer of reaction electrons, reducing charge transfer resistance, and improving 2e - ORR reaction kinetics. The dual-PEM reactor, constructed with this titanium carbide@carbon composite as electrodes, is a three-chamber solid electrolyte reactor separated by dual PEM membranes, capable of electrosynthesizing hydrogen peroxide across a full pH range. Compared to traditional PEM-AEM reactors, the dual-PEM reactor utilizes two more stable PEM membranes, effectively avoiding the relatively unstable AEM membrane and facilitating long-term stable operation.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] The present invention uses titanium carbide with high electrical conductivity as a carrier, and after hydrothermal calcination, a highly active carbon layer is coated on the surface to form a titanium carbide@carbon composite material. The carbon coating layer can isolate the direct contact between titanium carbide and the electrolyte, preventing TiC from oxidative corrosion under alkaline conditions to form TiO2, significantly extending the life of the catalyst. At the same time, the material has both the metallic conductivity of titanium carbide and strong adsorption of O2 molecules on the surface, as well as oxygen-containing functional groups (C=O, -COOH) and defect sites (sp 3 Hybridized carbon) can significantly accelerate the transfer of reaction electrons, reduce charge transfer resistance, and increase 2e - ORR reaction kinetics.
[0022] The present invention uses a dual PEM reactor. Under the action of the electric field, the alkali metal cations in the solid electrolyte (SE) liquid cavity pass through the second proton exchange membrane and react with the product of the two-electron oxygen reduction reaction at the cathode to form an alkaline H2O2 aqueous solution. +Under the action of the electric field, it passes through the first proton exchange membrane into the liquid cavity of SE and combines with it to form an acidic H2O2 aqueous solution. - The alkaline H2O2 aqueous solution of the group and the SE cavity have exactly the same amount of excess H + Neutralization of the acidic H2O2 aqueous solution can produce a neutral H2O2 aqueous solution.
[0023] Unlike existing reactors for synthesizing hydrogen peroxide (traditional PEM-AEM reactors), the present invention uses a dual proton membrane reactor. The PEM membrane is more stable and can effectively avoid the problem of anion membrane instability. At the same time, maintaining an alkaline environment in the cathode chamber is conducive to fully exerting the activity of the catalyst, thereby reducing energy consumption. It can also achieve the generation of hydrogen peroxide in the entire pH range, which is conducive to long-term stable operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Linear sweep voltammetry curves (a) and the relationship between current and time at a potential of 0.4 V vs. RHE (b) of the titanium carbide@carbon composite materials prepared under different conditions in Examples 1 to 3 and the titanium carbide material in Comparative Example 1;
[0025] Figure 2 The hydrogen peroxide concentration and Faraday efficiency of the titanium carbide@carbon composite materials prepared under different conditions in Examples 1 to 3 and the titanium carbide material in Comparative Example 1;
[0026] Figure 3 Schematic diagram of the continuous production of H2O2 solution over a full pH range using the titanium carbide@carbon composite material prepared in Example 1 in a dual-PEM reactor stack in Application Example 1; wherein, 1-anode chamber, 2-first proton exchange membrane, 3-solid electrolyte layer, 4-second proton exchange membrane, 5-cathode chamber, 11-gas diffusion electrode, 55-cathode electrode, 51-cathode chamber inlet, 52-cathode chamber outlet, 31-solid electrolyte layer outlet, 32-solid electrolyte layer inlet;
[0027] Figure 4 This is a graph showing the relationship between the hydrogen peroxide concentration at the cathode chamber outlet and the SE liquid chamber outlet and the flow rate in the continuous production of H2O2 in a full pH range under a flow state using the titanium carbide@carbon composite material prepared in Example 1 in a dual-PEM reactor stack of Application Example 1;
[0028] Figure 5 Graphs showing the relationship between the Faraday efficiency (a) and pH (b) at the cathode chamber outlet and the SE liquid chamber outlet as a function of flow rate in the continuous production of H2O2 over a full pH range using the titanium carbide@carbon composite material prepared in Example 1 in a dual-PEM reactor stack in Application Example 1;
[0029] Figure 6The Faraday efficiency change curve and current-voltage curve of the continuous production of H2O2 over the entire pH range using the titanium carbide@carbon composite material prepared in Example 1 in the dual-PEM reactor stack of Application Example 2;
[0030] Figure 7 This is a graph showing the relationship between pH and current density when the titanium carbide@carbon composite material prepared in Example 1 is used in the dual-PEM reactor stack of Application Example 2 to continuously produce H2O2. DETAILED DESCRIPTION
[0031] The present invention provides a method for preparing a titanium carbide@carbon composite material, comprising the following steps:
[0032] The titanium carbide and the sugar precursor aqueous solution are mixed with acid, and a hydrothermal reaction is carried out at a pH of 4 to 6 to obtain a composite;
[0033] The composite is calcined in a protective atmosphere to obtain a titanium carbide@carbon composite material.
[0034] In the present invention, the titanium carbide is preferably pretreated before use to remove the oxide layer on the surface. The pretreatment preferably includes: mixing commercially available titanium carbide powder with hydrochloric acid (mass fraction of 35-37%), placing the resulting mixture in a protective atmosphere (nitrogen or argon) for reflux treatment, and after the reflux is completed, the resulting mixed solution is centrifuged to collect black solids, washed with water until neutral, and dried to obtain titanium carbide powder; the reflux treatment temperature is preferably 40-60°C, more preferably 50-60°C, and the time is preferably 0.5-2h, more preferably 1-2h. The present invention has no special restrictions on the usage ratio of the commercially available titanium carbide powder and hydrochloric acid, and sufficient hydrochloric acid can be used.
[0035] In the present invention, the particle size of the titanium carbide is preferably 10 to 100 nm, more preferably 20 to 80 nm, and even more preferably 50 to 60 nm.
[0036] In the present invention, the carbohydrate precursor in the carbohydrate precursor aqueous solution includes one or more of glucose, sucrose and fructose; when the carbohydrate precursor is two or more of the above, the present invention has no special limitation on the ratio of different types of carbohydrate precursors, and any ratio is acceptable; the concentration of the carbohydrate precursor aqueous solution is preferably 0.01-1 mol / L, more preferably 0.05-0.5 M, and more preferably 0.1-0.3 M; the amount ratio of titanium carbide to the carbohydrate precursor aqueous solution is preferably 0.5 g:18-38 mL, more preferably 0.5 g:20-35 mL, and more preferably 0.5 g:25-30 mL.
[0037] In the present invention, the acid preferably includes any one of citric acid, acetic acid, phosphoric acid, hydrochloric acid, and sulfuric acid; the concentration of the acid is preferably 0.05 to 0.5 M, more preferably 0.1 to 0.4 M, and more preferably 0.2 to 0.3 M. The hydrothermal treatment is performed after adjusting the pH value with the acid to 4 to 6, more preferably 5 to 5.5.
[0038] In the present invention, the temperature of the hydrothermal reaction is preferably 120-200° C., more preferably 150-190° C., more preferably 160-180° C.; the time is preferably 6-24 h, more preferably 8-20 h, more preferably 12-16 h.
[0039] After the hydrothermal reaction is completed, the product is preferably centrifuged and washed and dried sequentially to obtain a composite. The drying temperature is preferably 40-80°C, more preferably 45-75°C, and more preferably 60-70°C; the drying time is preferably 5-12 hours, more preferably 6-10 hours, and more preferably 7-8 hours. The centrifugal washing process is not particularly limited in the present invention and can be performed according to procedures well known in the art.
[0040] In the present invention, the protective atmosphere is preferably nitrogen or argon; the calcination temperature is preferably 400-800°C, more preferably 450-700°C, and more preferably 500-550°C; the heating rate to the calcination temperature is preferably 1-5°C / min, more preferably 2-4°C / min, and more preferably 2.5-3°C / min; the calcination time is preferably 0.5-3h, more preferably 1-2.5h, and more preferably 1.5-2h.
[0041] The present invention provides a titanium carbide@carbon composite material prepared by the preparation method described in the above technical solution.
[0042] The present invention provides the use of the titanium carbide@carbon composite material described in the above technical solution in an electric reactor for electrosynthesis of hydrogen peroxide.
[0043] The present invention provides a dual-PEM reactor stack, which is composed of an anode chamber, a first proton exchange membrane, a solid electrolyte layer, a second proton exchange membrane and a cathode chamber arranged in sequence;
[0044] The anode chamber contains an anode electrode, and the anode liquid is pure water; the anode electrode is a gas diffusion electrode coated with iridium oxide;
[0045] The cathode chamber contains a cathode electrode, and the cathode liquid is an alkali metal cation solution; the cathode electrode is a porous carbon fiber felt coated with the titanium carbide@carbon composite material described in the above technical solution.
[0046] In the present invention, the dual PEM reactor stack is a solid electrolyte reactor stack having three chambers, namely, an anode chamber, a cathode chamber, and a solid electrolyte layer, separated by dual PEM membranes.
[0047] In the present invention, the method for preparing the anode electrode preferably comprises the following steps: ultrasonically dispersing iridium oxide, water, ionomer, and alcohol, and then spraying the resulting dispersion onto the surface of the gas diffusion electrode.
[0048] In the present invention, when preparing the anode electrode, the ionomer is preferably a perfluorosulfonic acid naphthol resin with a mass fraction of 5 to 20%, and the mass fraction is further preferably 6 to 15%, and more preferably 8 to 10%; the alcohol is any one of methanol, ethanol, isopropanol and n-propanol; the mass ratio of the iridium oxide, water, ionomer and alcohol is 1 to 2:5 to 30:0.25 to 0.75:5 to 30, and further preferably 1.2 to 1.8:10 to 20:0.3 to 0.6:5 to 20, and more preferably 1.3 to 1.5:12 to 16:0.4 to 0.5:10 to 15.
[0049] In the present invention, when preparing the anode electrode, the power of the ultrasonic dispersion is preferably 500-2230 W, more preferably 800-2000 W, and more preferably 1500-1800 W; the time of the ultrasonic dispersion is preferably 20-120 min, more preferably 40-100 min, and more preferably 60-90 min; the temperature of the ultrasonic dispersion is preferably 5-25°C, more preferably 7-20°C, and more preferably 8-10°C.
[0050] The present invention has no special limitation on the specific parameters of the spraying. The spraying can be carried out according to methods well known in the art. The temperature of the heating platform is 60° C. during the spraying process. Drying is performed while spraying to obtain the anode electrode.
[0051] In the present invention, the reaction occurring at the anode electrode is:
[0052] 2H2O→O2+4H + +4e -
[0053] In the present invention, the gas diffusion electrode is preferably GDS090S, W0S1011, TORAY TGP-H-060, Sigracet 28BC, Sigracet 35BC, Sigracet 39BB, Freudenberg H23C8, more preferably GDS090S, W1S1011, TORAY TGP-H-060, Sigracet28BC, Sigracet 35BC, Sigracet 39BB, more preferably GDS090S, W1S1011 or TORAY TGP-H-060; the iridium oxide loading on the gas diffusion electrode is 0.2 to 1.0 mg / cm 2 , more preferably 0.3 to 0.9 mg / cm 2 , more preferably 0.5 to 0.8 mg / cm 2 .
[0054] In the present invention, the alkali metal cations in the alkali metal cation solution include one or more of sodium ions, potassium ions, magnesium ions, calcium ions, and lithium ions; the alkali metal cation concentration in the alkali metal cation solution is preferably 0.01 to 1M, more preferably 0.05 to 0.5M, and more preferably 0.1 to 0.3M; when the alkali metal cations are two or more of the above, the present invention has no particular limitation on the ratio of the different types of alkali metal cations, and any ratio is acceptable. The present invention has no particular limitation on the type of anion in the alkali metal cation solution, and the corresponding anions well known in the art are sufficient; in an embodiment, the alkali metal cation solution is more preferably a sodium sulfate solution.
[0055] In the present invention, the method for preparing the cathode electrode preferably comprises the following steps: mixing titanium carbide@carbon composite material, alcohol, ionomer and water to obtain a dispersion, and spraying the dispersion on the surface of porous carbon fiber felt to obtain a cathode electrode;
[0056] In the present invention, when preparing the cathode electrode, the ionomer is preferably a polytetrafluoroethylene solution with a mass fraction of 5 to 60%, and the mass fraction is further preferably 10 to 50%, and more preferably 20 to 30%; the alcohol preferably includes any one of methanol, ethanol, isopropanol and n-propanol; the mass ratio of the titanium carbide@carbon composite material, alcohol, ionomer and water is preferably 2 to 4:5 to 10:1 to 5:6 to 12, further preferably 2.5 to 3.5:6 to 8:2 to 4:7 to 10, and more preferably 2.8 to 3:6.5 to 7.5:2.5 to 3.5:8 to 9.
[0057] When preparing the cathode electrode, the mixing is preferably carried out under ultrasonic dispersion conditions, and the power of the ultrasonic dispersion is preferably 500-2230 W, more preferably 800-2000 W, and more preferably 1200-1800 W; the time of the ultrasonic dispersion is preferably 20-120 min, more preferably 40-100 min, and more preferably 60-90 min; the temperature of the ultrasonic dispersion is preferably 5-25°C, more preferably 6-20°C, and more preferably 8-10°C.
[0058] In the present invention, the porous carbon fiber felt is preferably Sigracet ECM 250, Cetech GF020 or Cetech GF065, further preferably Sigracet ECM 250 or Cetech GF020, and more preferably Sigracet ECM250; the loading amount of the titanium carbide @ carbon composite material on the porous carbon fiber felt is preferably 1.0 to 5.0 mg / cm 2 , more preferably 1.5 to 4.5 mg / cm 2 , more preferably 2.0 to 4.0 mg / cm 2 .
[0059] In the present invention, the reaction occurring at the cathode electrode is:
[0060] O2+2H2O+mM n+ +2e - →H2O2+mM(OH) n
[0061] Wherein, M represents an alkali metal cation, and n represents the valence state of the alkali metal cation.
[0062] In the present invention, the first proton exchange membrane and the second proton exchange membrane are independently preferably one of N117, N115, and N212, more preferably N117 or N115, and more preferably N115.
[0063] In the present invention, the solid electrolyte in the solid electrolyte layer is preferably one or more of Dowex 50WX8 ion exchange resin, Amberlyst 15 ion exchange resin, Amberlite IRC120 cation exchange resin (sodium type), Amberlite IR120 cation exchange resin (hydrogen type), Amberlite IRC50, Amberlite 732 strong acid styrene cation exchange resin, macroporous weak acid cation exchange resin and D152 macroporous acrylic weak acid cation exchange resin; further preferably Dowex 50WX8 ion exchange resin, Amberlyst 15 ion exchange resin, Amberlite IRC120 cation exchange resin (sodium type), Amberlite IRC50, Amberlite 732 strong acid styrene cation exchange resin or macroporous weak acid cation exchange resin, more preferably Dowex 50WX8 ion exchange resin, Amberlyst 15 ion exchange resin, Amberlite IRC120 cation exchange resin (sodium type) or Amberlite 732 strong acid styrene cation exchange resin; when the solid electrolyte is two or more of the above, the present invention has no special limitation on the ratio of different types of solid electrolytes, and can be filled according to actual needs.
[0064] In the present invention, the particle size of the solid electrolyte is preferably 25-200 mesh, more preferably 50-100 mesh; the thickness of the solid electrolyte layer formed by the solid electrolyte is preferably 1.5-3 mm, more preferably 1.8-2.58 mm, and more preferably 2.08-2.36 mm.
[0065] In the present invention, the first proton exchange membrane and the second proton exchange membrane are attached to the two side surfaces of the substrate, and the cavity inside the substrate is filled with a solid electrolyte (ion conductor (H + or alkali metal ions); the substrate is preferably an organic glass plate or a polytetrafluoroethylene plate.
[0066] In the present invention, the reaction occurring in the solid electrolyte liquid cavity is:
[0067] H2O2+mM(OH) n +2H + →H2O2+mnH2O+mM n+ +(2-mn)H +
[0068] The present invention does not specifically limit the assembly method of the dual PEM reactor. The anion membrane in the existing PEM-AEM reactor can be replaced with a proton membrane in a manner well known in the art. The water and oxygen in the present invention enter from the cathode chamber inlet 51, flow out from the cathode chamber outlet 52, and are collected in the hydrogen peroxide solution storage tank (alkaline). The liquid in the storage tank is pumped to the solid electrolyte layer inlet 32 by a peristaltic pump, and then flows out from the solid electrolyte layer outlet 31 (acidic). The source of water in the existing PEM-AEM reactor is the humidified air in the cathode chamber, which produces HO2 - Ions are transferred to the solid electrolyte through the anion membrane, and water flows through the solid electrolyte layer, carrying out hydrogen peroxide.
[0069] The present invention provides the use of the dual PEM reactor described in the above technical solution in the electrosynthesis of hydrogen peroxide over the entire pH range.
[0070] The present invention has no particular limitation on the method for electrosynthesizing hydrogen peroxide in a dual-PEM reactor within a full pH range, and the method may be applied according to methods well known in the art.
[0071] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.
[0072] The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and raw materials, unless otherwise specified, are commercially available.
[0073] The titanium carbide powder used in the following examples is pretreated titanium carbide. The specific processing steps are as follows: 0.5 g of commercially available titanium carbide powder is mixed with 30 mL of hydrochloric acid (mass fraction of 35-37%), and the resulting mixture is placed in a nitrogen atmosphere and refluxed at 60°C for 2 h. After the reflux is completed, the resulting mixed solution is centrifuged to collect black solids, washed with water until neutral, and dried to obtain titanium carbide powder with a particle size of 10-100 nm.
[0074] Example 1
[0075] 0.5 g of titanium carbide powder and 35 mL of 0.1 M glucose aqueous solution were mixed evenly, 0.2 M citric acid aqueous solution was added to the mixed solution to adjust the pH to 5.5, and then poured into a 50 mL polytetrafluoroethylene-lined reactor and reacted at a constant temperature of 160 ° C for 12 hours; the reacted solution was centrifuged and washed and dried at 60 ° C for 10 hours to obtain a black solid; the black solid was placed in a nitrogen atmosphere and heated to 550 ° C at a heating rate of 2.5 ° C / min and calcined for 1 hour to obtain a titanium carbide @ carbon composite material.
[0076] Example 2
[0077] 0.5 g of titanium carbide powder and 30 mL of 0.05 M glucose aqueous solution were mixed evenly, 0.2 M citric acid aqueous solution was added to the mixed solution to adjust the pH to 5, and then poured into a 50 mL polytetrafluoroethylene-lined reactor and reacted at a constant temperature of 120 ° C for 16 hours; the reacted solution was centrifuged and washed and dried at 60 ° C for 10 hours to obtain a black solid; then the black solid was placed in an argon atmosphere and heated to 500 ° C at a heating rate of 2.5 ° C / min and calcined for 1 hour to obtain a titanium carbide @ carbon composite material.
[0078] Example 3
[0079] 0.5 g of titanium carbide powder and 30 mL of 0.5 M glucose aqueous solution were mixed evenly, 0.2 M hydrochloric acid aqueous solution was added to the mixed solution to adjust the pH to 5.5, and then poured into a 50 mL polytetrafluoroethylene-lined reactor and reacted at a constant temperature of 180 ° C for 24 hours; the reacted solution was centrifuged and washed and dried at 60 ° C for 10 hours to obtain a black solid; then the black solid was placed in a nitrogen atmosphere and heated to 700 ° C at a heating rate of 5 ° C / min and calcined for 1 hour to obtain a titanium carbide @ carbon composite material.
[0080] Comparative Example 1
[0081] 0.5 g of commercially available titanium carbide powder was mixed with 30 mL of hydrochloric acid (mass fraction of 35-37%), and the resulting mixture was placed in a nitrogen atmosphere and refluxed at 60°C for 2 h. After the reflux period, the resulting mixed solution was centrifuged to collect the black solid, washed with water until neutral, and dried to obtain titanium carbide powder.
[0082] Performance Testing
[0083] Figure 1 The titanium carbide@carbon composite materials prepared under different conditions in Examples 1 to 3 and the titanium carbide material of Comparative Example 1 were sprayed on the gas diffusion layer as electrodes, and the electrochemical performance was tested in an H-type cell with 0.1M KOH. The linear sweep voltammetry curves are as follows: Figure 1As shown in (a), the limiting current density is Example 1>Example 2>Comparative Example 1>Example 3, indicating that Example 1 has the best two-electron oxygen reduction reaction activity.
[0084] The relationship curves of the current and time of the titanium carbide@carbon composite materials prepared under different conditions in Examples 1 to 3 and the titanium carbide material of Comparative Example 1 at a potential of 0.4 V vs. RHE are shown in FIG. Figure 1 As shown in (b). When the ORR potential is 0.4V vs. RHE, the cathode current density of Example 1 is -16.12mA / cm 2 , which is higher than other electrodes with the same effective area, Example 2 (-15.26 mA / cm 2 ), Example 3 (-12.43 mA / cm 2 ), Comparative Example 1 (-12.89 mA / cm 2 ), the wide variation of ORR current response indicates that Example 1 has excellent ORR activity and faster electron-proton transfer ability.
[0085] Figure 2 The titanium carbide@carbon composite materials prepared under different conditions in Examples 1 to 3 and the titanium carbide material of Comparative Example 1 were used as electrodes, and the hydrogen peroxide concentration and Faradaic efficiency were electrosynthesized in an H-type cell, 0.1 M KOH, and 0.4 V vs. RHE potential for 10 min to evaluate their ability to produce H2O2. Figure 2 As shown in the figure, after 10 minutes, the H2O2 concentrations of the electrodes of Example 1, Example 2, Example 3, and Comparative Example 1 were 40.48, 36.8, 27.6, and 29.44 mg / L, respectively. At the same time, the Faradaic efficiencies of the electrodes of Example 1, Example 2, Example 3, and Comparative Example 1 at a potential of 0.4 V vs. RHE were 95.04, 91.25, 84.00, and 86.42%, respectively, indicating that Example 1 had the best ORR activity and selectivity.
[0086] Application Example 1
[0087] like Figure 3 As shown, the double PEM membrane reactor stack is composed of an anode chamber 1, a first proton exchange membrane 2, a solid electrolyte layer 3, a second proton exchange membrane 4 and a cathode chamber 5 in sequence; the anode chamber 1 and the solid electrolyte layer 3 are separated by the first proton exchange membrane 2, and the cathode chamber 5 and the solid electrolyte 3 are separated by the second proton exchange membrane 4; the first proton exchange membrane 2 and the second proton exchange membrane 4 are attached to the surfaces of both sides of a polytetrafluoroethylene plate, and the cavity inside the polytetrafluoroethylene plate is filled with a solid electrolyte to form the solid electrolyte layer 3; water and oxygen flow into the cathode chamber from the cathode chamber inlet 51, flow out from the cathode chamber outlet 52, and are collected in a storage tank (alkaline). The liquid in the beaker is pumped to the solid electrolyte layer inlet 32 by a peristaltic pump, and then flows out from the solid electrolyte layer outlet 31 (acidic):
[0088] Among them, the first proton exchange membrane is N117, and the second proton exchange membrane is N117;
[0089] The anolyte in the anode chamber is pure water, and the anode electrode in the anode chamber is a gas diffusion electrode 11 containing an iridium oxide coating and is connected to the positive electrode of the power supply. The iridium oxide loading is 0.5 mg / cm 2 ;
[0090] Preparation of the anode electrode: 0.25 g of iridium oxide was sequentially mixed with 3.75 g of water, 0.3125 g of 20% perfluoronaphthol sulfonate resin, and 3.75 g of isopropyl alcohol under ultrasonic dispersion power of 800 W and ultrasonic temperature of 10°C for 60 min to obtain a uniform dispersion; the dispersion was then sprayed onto the surface of a W0S1011 gas diffusion electrode until the iridium oxide loading reached 0.5 mg / cm 2 .
[0091] The cathode liquid in the cathode chamber is a 0.5M sodium sulfate aqueous solution. The cathode electrode 55 in the cathode chamber is a porous carbon fiber felt coated with the titanium carbide@carbon composite material of Example 1 and is connected to the negative electrode of the power supply. The loading of the titanium carbide@carbon composite material is 2.5 mg / cm 2 The solid electrolyte is a 2:1 mass ratio of Amberlite IRC120 cation exchange resin (sodium type) and Amberlite 732 strong acid styrene cation exchange resin, the particle size of the solid electrolyte is 25 to 200 mesh, and the thickness of the solid electrolyte layer is 2.36 mm;
[0092] Preparation of cathode electrode: 2.0g titanium carbide@carbon composite material was mixed with 6.54g isopropanol, 7.14g 20% polytetrafluoroethylene solution and 9.32g water in sequence under ultrasonic dispersion power of 1200W and ultrasonic temperature of 6°C for 60min to obtain a uniform dispersion; the dispersion was then sprayed onto the surface of Sigracet ECM 250 porous carbon fiber felt until the titanium carbide@carbon composite material loading was 2.5mg / cm 2 .
[0093] The method for electrosynthesizing H2O2 using the above device is as follows: deionized water with a circulation rate of 40 mL / min is introduced into the anode side. On the cathode side, oxygen (flow rate 800 sccm) is mixed with 0.5M sodium sulfate solution at 8 mL / min, 14 mL / min, and 18 mL / min respectively, and then flows into the cathode chamber to generate excess OH. - The alkaline H2O2 solution of the group flows out into the storage tank, and then the peristaltic pump is turned on to collect the cathode chamber into the storage tank to obtain the alkaline H2O2 solution. Then the alkaline H2O2 solution in the storage tank will be continuously pumped into the SE liquid cavity to obtain the acidic H2O2 solution with excess protons.
[0094] Figure 3 Schematic diagram of continuous production of H2O2 solution in a full pH range using the titanium carbide@carbon composite material prepared in Example 1 in a dual PEM reactor in Application Example 1; Figure 3 It can be seen that the double PEM membrane is divided into three chambers of the double PEM reactor. The cathode chamber and the anode chamber are separated by a solid electrolyte, and two identical PEMs are sandwiched in the middle. The cathode side continuously provides a mixture of O2 flow and water flow for 2e - In the ORR, H2O circulates on the anode side for oxygen evolution reaction. In the middle chamber, a SE layer composed of cation exchange resin is used to minimize the pressure drop between the cathode and anode.
[0095] Figure 4 This is a graph showing the relationship between the hydrogen peroxide concentration at the cathode chamber outlet and the SE liquid chamber outlet and the flow rate change in the continuous production of H2O2 in the full pH range under the overflow state in the dual PEM reactor of Application Example 1 using the titanium carbide @ carbon composite material prepared in Example 1; Figure 4 It can be seen that with the increase of water flow rate, the residence time of H2O2 product in the cathode chamber and SE chamber and the concentration of H2O2 product solution at the outlet can be adjusted. 2 At a current density of 1.5 A (total current 2.5 A), the water flow rates were 8, 14, and 18 mL / min, and the concentrations at the cathode chamber outlet were 3100.06, 1795.48, and 1349.03 mg / L, respectively; the concentrations at the SE chamber outlet were 2930.32, 1709.68, and 1301.29 mg / L, respectively; the concentrations in the cathode chamber were almost equivalent to those in the SE chamber, indicating that H2O2 was effectively discharged.
[0096] Figure 5Figure 1 shows the relationship between the Faraday efficiency (a) and pH (b) at the cathode chamber outlet and the SE liquid chamber outlet under flow conditions for continuous production of H2O2 over a full pH range in a dual-PEM reactor using the titanium carbide@carbon composite material prepared in Example 1. At a water flow rate of 14 mL / min, the cathode chamber and SE chamber both achieved the highest Faraday efficiencies of 95.11% and 90.57%, respectively, compared to 8 mL / min (93.84% and 88.77%) and 18 mL / min (91.88% and 88.63%). The Faraday efficiency increases and then decreases with increasing flow rate. This is because the H2O2 generated at lower flow rates cannot diffuse away from the electrode surface in time, potentially leading to further decomposition and reduced selectivity. Higher flow rates may strip oxygen molecules adsorbed on the electrode surface, reducing the effective area for the reaction and resulting in a decrease in Faraday efficiency. Furthermore, the pH value in the cathode chamber gradually decreases with increasing water flow rate. The pH value within the SE chamber gradually increases as the water flow rate increases. This is due to the dilution effect of the water flow, which causes local pH changes. A neutral H2O2 solution can be obtained by mixing the alkaline H2O2 solution in the cathode chamber with the acidic H2O2 solution in the SE chamber.
[0097] Application Example 2
[0098] The other conditions in Application Example 1 remain unchanged, and the aqueous solution in the cathode chamber is directly introduced into the solid electrolyte chamber.
[0099] Figure 6 In the dual PEM reactor of Application Example 2, the titanium carbide@carbon composite material prepared in Example 1 was used at 25 cm 2 The Faraday efficiency change curve and current-voltage curve of continuous production of H2O2 over the full pH range in a dual PEM reactor; Figure 6 As shown, at 80, 160, and 240 mA cm -2 At the current density, the cell voltage was 2.35, 3, and 3.64 V, respectively. By increasing the current density, the cell voltage of the dual-PEM reactor gradually increased. Especially at higher operating currents, the increased cell voltage indicates a decrease in battery performance. However, the Faradaic efficiency of electrosynthesized H2O2 remained above 70% across the entire cell voltage range (240 mA cm -2 The Faradaic efficiency is 72.11% under 80 mA cm -2 The highest reached 97.74%.
[0100] Figure 7 The titanium carbide@carbon composite material 25cm prepared in Example 1 is used in the dual PEM reactor of Application Example 2. 2 pH variation curve of continuous production of H2O2 in dual PEM reactor; Figure 7 As shown in Figure 3, the pH value barely changes and is approximately 6.5 with the increase of current density.
[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.
Claims
1. A method for preparing a titanium carbide@carbon composite material, characterized in that: The following steps are involved: The titanium carbide and the sugar precursor aqueous solution are mixed with acid, and a hydrothermal reaction is carried out at a pH of 4 to 6 to obtain a composite; The composite is calcined in a protective atmosphere to obtain a titanium carbide@carbon composite material.
2. The preparation method according to claim 1, characterized in that The particle size of the titanium carbide is 10 to 100 nm; the sugar precursor in the sugar precursor aqueous solution includes one or more of glucose, sucrose and fructose; the concentration of the sugar precursor aqueous solution is 0.01 to 1 mol / L; the usage ratio of the titanium carbide to the sugar precursor aqueous solution is 0.5 g:18 to 38 mL.
3. The preparation method according to claim 2, characterized in that The acid includes any one of citric acid, acetic acid, phosphoric acid, hydrochloric acid and sulfuric acid; the temperature of the hydrothermal reaction is 120-200° C., and the time is 6-24 hours.
4. The preparation method according to claim 3, characterized in that The protective atmosphere is nitrogen or argon; the calcination temperature is 400-800° C., the heating rate to the calcination temperature is 1-5° C. / min, and the calcination time is 0.5-3 h.
5. The titanium carbide@carbon composite material prepared by the preparation method according to any one of claims 1 to 4.
6. Use of the titanium carbide@carbon composite material according to claim 5 in a reactor stack for electrosynthesis of hydrogen peroxide.
7. A dual PEM reactor, characterized in that: The dual PEM reactor stack consists of an anode chamber, a first proton exchange membrane, a solid electrolyte layer, a second proton exchange membrane and a cathode chamber arranged in sequence; The anode chamber contains an anode electrode, and the anode liquid is pure water; the anode electrode is a gas diffusion electrode coated with iridium oxide; The cathode chamber contains a cathode electrode, and the cathode liquid is an alkali metal cation solution; the cathode electrode is a porous carbon fiber felt coated with the titanium carbide@carbon composite material according to claim 5.
8. The dual PEM reactor stack according to claim 7, characterized in that: The preparation method of the cathode electrode comprises the following steps: mixing titanium carbide@carbon composite material, alcohol, ionomer and water to obtain a dispersion, and spraying the dispersion on the surface of porous carbon fiber felt to obtain a cathode electrode; the ionomer is a polytetrafluoroethylene solution with a mass fraction of 5 to 60%; the alcohol includes any one of methanol, ethanol, isopropanol and n-propanol; the loading amount of the titanium carbide@carbon composite material on the porous carbon fiber felt is 1.0 to 5.0 mg / cm 2 .
9. The dual PEM reactor stack according to claim 7, characterized in that: The alkali metal cations in the alkali metal cation solution include one or more of sodium ions, potassium ions, magnesium ions, calcium ions and lithium ions; the first proton exchange membrane and the second proton exchange membrane are independently one of N117, N115, and N212; the first proton exchange membrane and the second proton exchange membrane are attached to the surfaces of both sides of the substrate, and the cavity inside the substrate is filled with a solid electrolyte.
10. Use of the dual PEM reactor stack according to any one of claims 7 to 9 in the electrosynthesis of hydrogen peroxide in the full pH range.