Method for efficiently oxidizing glycerol into glyceraldehyde under high-potential condition
By constructing a TiO2-modified graphite felt cathode activated by pulse voltage, active hydrogen and hydroxyl radical compounds are generated, which solves the problem of low selectivity in the electrocatalytic oxidation of glycerol, realizes the efficient conversion of glycerol into glyceraldehyde, and enhances the economic value of biomass resources.
Patent Information
- Application Number
- CN202511219766.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2025-10-10
AI Technical Summary
In the existing technology, the C3 product selectivity in the glycerol electrocatalytic oxidation process is low and over-oxidation is serious. Traditional cathode materials have low active hydrogen yield or are easily oxidized and inactivated at high potentials, making it difficult to achieve the synergistic effect of active hydrogen and hydroxyl radicals.
A specific electro-Fenton cathode system was constructed, and TiO2-modified graphite felt was activated by pulse voltage to generate active hydrogen, which combined with hydroxyl radicals to form hydrogen-bound hydroxyl radicals with moderate oxidative activity, thereby regulating the oxidation reaction path and inhibiting the breakage of CC bonds.
The efficient and highly selective conversion of glycerol into glyceraldehyde at high current density was achieved, breaking through the bottleneck of traditional technology where both yield and selectivity cannot be achieved simultaneously, and providing a green and efficient path for the high-value conversion of glycerol.
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Figure CN120758893A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electrocatalytic synthesis and high-value utilization of biomass, and specifically relates to a method for achieving directional oxidation of glycerol by regulating reactive species (hydroxyl radicals and active hydrogen) under high potential (high current density) conditions. The method is particularly suitable for efficiently converting glycerol, a by-product of biodiesel, into the high-value-added chemical glyceraldehyde, providing key technical support for green catalysis and low-carbon chemical industry. Background Art
[0002] As the global "dual carbon" goals advance, the replacement of fossil fuels with renewable energy is becoming an inevitable trend. Biodiesel, a typical renewable liquid fuel, has seen rapid growth in production in recent years. During biodiesel production, 1 ton of glycerin byproduct is produced for every 10 tons of biodiesel, leading to a severe oversupply of glycerin in the global market. The accumulation of glycerin at low prices not only wastes biomass resources but also poses environmental risks. Therefore, developing pathways for the high-value conversion of glycerin has become a key bottleneck restricting the sustainable development of the biodiesel industry.
[0003] Converting glycerol into C3 oxygenated chemicals such as glyceraldehyde and dihydroxyacetone can not only preserve the integrity of the carbon chain (avoiding low-carbon by-products) but also significantly increase added value, making it the most economically beneficial utilization direction at present. Electrochemical oxidation technology is considered one of the core technologies for the targeted synthesis of glycerol C3 products due to its mild reaction conditions and environmental friendliness. However, this technology has a difficult-to-break-through "selectivity-yield trade-off": the yield of glycerol oxidation products is limited at low current density; and when the potential (or current density) is increased, the CC bond in the glycerol molecule will break, generating low-value products such as formic acid and CO2, resulting in a sharp drop in the selectivity of C3 products.
[0004] As an advanced oxidation technology based on the in-situ generation of ·OH, the electro-Fenton method has been tried for glycerol oxidation, but it also faces the problem of over-oxidation of ·OH. Due to the high oxidation potential of ·OH, it will indiscriminately attack the hydroxyl group and carbon chain in the glycerol molecule, resulting in very low selectivity for C3 products. Studies have shown that if reducing species can be introduced into the system to regulate the activity of ·OH, its effect on the breakage of CC bonds can be effectively inhibited, thereby improving the selectivity of C3 products. Among them, active hydrogen (*H), as a highly active reducing intermediate, can effectively reduce the oxidative activity of ·OH by forming hydrogen bonds or covalent bonds (such as *H-OH) with it, while promoting the dehydrogenation reaction of the hydroxyl group in the glycerol molecule (to form aldehyde groups). In theory, this can simultaneously increase the rate of glycerol oxidation and the selectivity of C3 products.
[0005] However, existing technologies have struggled to achieve efficient production of active hydrogen and targeted regulation of ·OH. Conventional cathode materials (such as carbon materials and precious metals) either have low active hydrogen yields or are easily deactivated by ·OH oxidation at high potentials, making it impossible to stably construct a synergistic "active hydrogen-·OH" system. Therefore, developing a cathode catalytic system that can generate active hydrogen at high potentials and precisely regulate the activity of the ·OH reaction has become a key technical challenge in achieving efficient and targeted oxidation of glycerol to glyceraldehyde, and is of great significance for promoting the high-value utilization of biomass resources and upgrading electrocatalytic synthesis technologies. Summary of the Invention
[0006] The present invention aims to overcome the defects of low selectivity and severe over-oxidation of C3 products in the electrocatalytic oxidation of glycerol in the prior art. By constructing a novel electro-Fenton cathode catalytic system, the efficient generation of reductively active hydrogen (*H) is achieved, and its directed binding with the hydroxyl radicals (·OH) generated in situ by the electro-Fenton method is achieved to form hydrogen-bound hydroxyl radicals (*H-OH) with moderate oxidative activity. This allows precise control of the oxidation reaction pathway, inhibits C-C bond cleavage, and ultimately achieves the efficient and highly selective conversion of biomass feedstocks such as glycerol into high-value-added C3 products such as glyceraldehyde at high current density.
[0007] In order to achieve the purpose, the present invention adopts the following technical solutions:
[0008] The present invention discloses a method for efficiently oxidizing glycerol to glyceraldehyde under high-potential conditions. By constructing a specific electro-Fenton cathode system, the reactive species are regulated to achieve the targeted conversion of glycerol. The preparation method of a TiO2-modified graphite felt activated by a pulsed voltage as the cathode comprises the following steps:
[0009] S1. Graphite felt surface activation
[0010] The graphite felt is immersed in a concentrated nitric acid solution, heated and stirred in a water bath at 50-70° C. for surface activation; after activation, it is first washed with ultrapure water until neutral and dried, and then ultrasonically washed in ethanol, acetone, and ultrapure water in sequence to remove surface grease and impurities, and then dried to obtain a surface-activated graphite felt.
[0011] S2, Growth of TiO2 on graphite felt surface and activation
[0012] Tetrabutyl titanate, ultrapure water, and concentrated hydrochloric acid are mixed in a volume ratio of 0.5-1:10-40:10-25, and then ammonium fluorotitanate is added at a concentration of 1-2 g / 100 mL, and stirred for 10-30 minutes until completely dissolved to prepare a precursor solution.
[0013] The surface-activated graphite felt obtained in step S1 is immersed in the above-mentioned precursor solution, placed in a hydrothermal reactor, and subjected to a constant temperature hydrothermal reaction at 120-180°C for 10-16 hours; after the reaction is completed, it is washed with acetone and ethanol in sequence to remove unreacted impurities, and after drying, it is annealed at 400-600°C in a nitrogen atmosphere for 1-3 hours to obtain TiO2-modified graphite felt.
[0014] In a three-electrode system, the TiO2-modified graphite felt is used as the working electrode, a high-purity nickel plate or platinum plate is used as the counter electrode, and Ag / AgCl is used as the reference electrode. The electrodes are immersed in an electrolyte solution (electrolyte selected from sodium sulfate, potassium sulfate, sodium perchlorate, or a mixture of sodium sulfate and sodium bisulfate); a periodic rectangular wave pulse voltage (high potential segment -2V to -4V, low potential segment 0V, frequency 1Hz to 100Hz, duty cycle 70%-90%) is applied for electrolysis for 2-4 hours to activate TiO2. The high potential segment drives oxygen vacancies and Ti 3+ Active sites are generated to improve the electron transfer efficiency, and the titanium dioxide structure is stabilized in the low potential range to prevent collapse, and finally a TiO2-modified graphite felt cathode activated by pulse voltage is obtained.
[0015] The present invention provides a method for efficiently oxidizing glycerol to glyceraldehyde under high-potential conditions. The specific steps are as follows: in a three-electrode system, the aforementioned pulse-voltage-activated TiO2-modified graphite felt is used as the cathode, forming an electrolysis circuit with the anode; in a reaction system containing glycerol and a supporting electrolyte, a high voltage is applied to generate a high current density. Under this high-voltage condition, the pulse-voltage-activated TiO2-modified graphite felt can efficiently promote the dissociation of water to produce active hydrogen (*H); simultaneously, an electro-Fenton reaction generates hydroxyl radicals (·OH) in situ, and *H combines with ·OH to form a hydrogen-bound hydroxyl radical (*H-OH) with moderate oxidative activity. This species can not only efficiently oxidize glycerol, but also significantly inhibit C-C bond cleavage, thereby regulating the glycerol oxidation pathway to achieve highly selective conversion to glyceraldehyde.
[0016] Furthermore, the amount of glycerol added to the reaction system is 50-400 mM, and the high voltage is -2.5 V to -4 V, so that the glycerol undergoes oxidation reaction under constant current (100-400 mA) conditions.
[0017] Furthermore, the supporting electrolyte is sodium sulfate, potassium sulfate, sodium perchlorate, or a mixture of sodium sulfate and sodium bisulfate, and the supporting electrolyte concentration is 80-100 mmol / L.
[0018] Furthermore, the anode material is selected from a titanium-based ruthenium-iridium coated electrode, a boron-doped diamond electrode, or a platinum electrode;
[0019] Furthermore, before applying a high voltage to initiate the reaction, oxygen is introduced into the reaction system to saturate it with oxygen. The reaction is carried out under acidic to neutral conditions (pH = 1-7), which can be adjusted by adding 0.5-2 mM hydrochloric acid or sodium hydroxide. When the reaction system is acidic, 0.2-0.5 mmol / L of ferrous salt (ferrous sulfate or ferrous chloride) can be added to the system to promote the formation of hydroxyl groups in the electro-Fenton process.
[0020] By regulating the synergistic effects of active species, this invention overcomes the trade-off between glycerol oxidation yield and selectivity in traditional electrocatalysis, providing an efficient and green technical path for high-value-added conversions such as glycerol. Compared with existing technologies, the present invention has the following advantages:
[0021] (1) This invention achieves the directional generation of hydrogen-bound hydroxyl radicals (*H-OH) for the first time through the design of a TiO2-modified graphite felt cathode activated by pulse voltage, solving the problem of CC bond breakage caused by the excessive oxidative activity of hydroxyl radicals (·OH) in traditional electro-Fenton systems. This strategy, based on the regulation of active species, achieves highly selective conversion of glycerol to glyceraldehyde without the need for complex equipment, breaking through the bottleneck of the existing technology of "high yield and high selectivity cannot be achieved at the same time."
[0022] (2) The present invention proposes a new mechanism for the TiO2 cathode to produce active hydrogen (*H) by pulse voltage activation and synergistic action with ·OH: by driving oxygen vacancies and TiO2 to form a new structure, the TiO2 cathode generates active hydrogen (*H) by pulse voltage activation and synergistic action with ·OH. 3+ The formation of active sites enhances the efficiency of active hydrogen generation. At the same time, the precise combination of active hydrogen and ·OH is used to regulate the oxidation activity, achieving molecular-level precise regulation of the glycerol oxidation pathway, and providing a new idea for the design of active species for selective oxidation reactions of biomass.
[0023] (3) This invention establishes a green conversion pathway using glycerol, a byproduct of biodiesel, as raw material. Through electrocatalysis, high-value-added glyceraldehyde can be efficiently prepared under mild conditions (acidic to neutral, at room temperature and pressure). The entire process requires no external chemical oxidants and relies solely on electrons as a "cleaning agent." This not only addresses the environmental issues caused by excess glycerol, but also enhances the economic value of biomass resources, providing a feasible solution for the coordinated development of low-carbon chemical and sustainable energy industries.
[0024] (4) This invention reveals the core role of "active hydrogen regulating hydroxyl activity" in glycerol oxidation and clarifies the critical significance of *H-OH as a mild oxidizing species in preserving carbon chain integrity. This discovery not only provides theoretical support for the high-value conversion of glycerol, but also expands the research dimension of the coordinated regulation of active species in electrocatalytic systems, providing a universal principle that can be used as a reference for the selective conversion of other polyhydroxy compounds. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0026] Figure 1 This is the SEM image of the activated TiO2 modified graphite felt prepared in Example 1 of the present invention.
[0027] Figure 2 2 is the oxidation product distribution diagram and glyceraldehyde selectivity curve at different glycerol concentrations in Example 2.
[0028] Figure 3 This is the curve of product change over time at 200 mM glycerol concentration in Example 2.
[0029] Figure 4 This is the electron paramagnetic resonance detection diagram of the reaction system in Example 2.
[0030] Figure 5 This is a SEM image of the activated TiO2-modified graphite felt cathode after reaction for 16 hours under 200 mM glycerol concentration conditions in Example 2.
[0031] Figure 6 This is a high-resolution transmission electron microscopy image of the activated TiO2-modified graphite felt cathode after 16 hours of reaction under 200 mM glycerol concentration conditions in Example 2.
[0032] Figure 7 3 shows the oxidation product distribution diagram and glyceraldehyde selectivity curve at different glycerol concentrations in Example 3.
[0033] Figure 8 This is the curve of product change over time at 200 mM glycerol concentration in Example 3.
[0034] Figure 9 This is a comparison diagram of oxidation products at different voltages in Example 3.
[0035] Figure 10 These are the solid-state nuclear magnetic resonance test images of the activated TiO2-modified graphite felt in Example 3, which were unreacted, reacted at a low voltage (-1.5V) for 16h, and reacted at a high voltage (-3V) for 16h. DETAILED DESCRIPTION
[0036] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.
[0037] The materials and instruments used in the following examples are all commercially available.
[0038] Example 1
[0039] In this embodiment, TiO2 modified graphite felt activated by pulse voltage (hereinafter referred to as activated TiO2 modified graphite felt) was prepared according to the following steps:
[0040] S1. Graphite felt surface activation
[0041] Concentrated nitric acid (HNO3) was measured and the graphite felt was immersed in the concentrated nitric acid. The surface was activated by heating and stirring in a water bath at 60°C for 4 hours. After activation, the graphite felt was washed with ultrapure water until neutral, dried in an oven at 60°C for 12 hours, and then ultrasonicated in ethanol, acetone, and ultrapure water for 15 minutes each to remove residual grease and impurities on the surface. Finally, the graphite felt was dried in an oven at 60°C for 12 hours to obtain surface-activated graphite felt.
[0042] S2, TiO2 grows on the surface of graphite felt and activates
[0043] Tetrabutyl titanate, ultrapure water, and concentrated hydrochloric acid were mixed in a volume ratio of 1:35:25, and ammonium fluorotitanate was added at a concentration of 1g / 100mL. The mixture was stirred for 20 minutes until completely dissolved to prepare a precursor solution. The surface-activated graphite felt prepared in step S1 was immersed in the precursor solution and placed in a hydrothermal reactor for a hydrothermal reaction at a constant temperature of 180°C for 16 hours. After the reaction, the electrode was washed with acetone and then ethanol to remove unreacted impurities. The electrode was removed and dried in a 60°C oven for 12 hours. It was then annealed at 550°C in a nitrogen atmosphere for 2 hours to obtain TiO2-modified graphite felt.
[0044] In a three-electrode system, the above-mentioned TiO2-modified graphite felt was used as the cathode, the platinum electrode as the anode, and Ag / AgCl as the reference electrode. Sodium sulfate / sodium bisulfate buffer solution (the concentrations of sodium sulfate and sodium bisulfate were both 0.05 mol / L) was used as the electrolyte solution. A pulse voltage (high potential section -3V, low potential section 0V, frequency 20Hz, duty cycle 70%) was applied for electrolysis for 2h to obtain activated TiO2-modified graphite felt.
[0045] See also Figure 1 The surface morphology of the activated TiO2 modified graphite felt prepared in this example was characterized by SEM. It can be clearly observed from the figure that titanium dioxide is uniformly loaded on the surface of the graphite felt to form a continuous and stable covering layer.
[0046] Example 2
[0047] This example uses the activated TiO2-modified graphite felt cathode prepared in Example 1 to directionally catalyze the high-value conversion of glycerol under acidic conditions:
[0048] In a three-electrode system, the activated TiO2-modified graphite felt prepared in Example 1 was used as the cathode, a platinum electrode was used as the anode, and an Ag / AgCl reference electrode was used. 50 mmol, 100 mol, 200 mmol, 250 mmol, 300 mmol, and 400 mmol of glycerol (corresponding to a concentration of 50-400 mM) were dissolved in 1000 mL of water. Sodium bisulfate and sodium sulfate were added as supporting electrolytes (total concentration of 100 mmol / L, 50 mmol / L each), and 0.2 mmol of ferrous sulfate was added to form a reaction system (at an acidic pH of approximately 1.2, without adding acid or base to adjust the pH). Oxygen was introduced into the reaction system at a rate of 0.5 L / min for 10 minutes, and then a high voltage of -3 V was applied, generating a high current density of approximately 150 mA to carry out the glycerol oxidation reaction.
[0049] After filtering the solution after the above reaction, the product was detected by liquid chromatography. Under the condition of 200mM glycerol concentration, 400μL of the reaction solution was taken every 2h during the reaction, filtered, and the product changes were analyzed by liquid chromatography. In addition, to verify that the activated TiO2-modified graphite felt cathode produced active hydrogen (*H) during the reaction, 5,5-dimethyl-1-pyrroline oxide (DMPO) was used to capture the active hydrogen in the system after 1 hour of reaction.
[0050] refer to Figure 2 (Oxidation product distribution diagram and glyceraldehyde selectivity curve at different glycerol concentrations in Example 2): After 16 hours of reaction, liquid chromatography detection results showed that at each glycerol concentration, the activated TiO2-modified graphite felt cathode could highly selectively oxidize glycerol to glyceraldehyde, confirming the precise regulatory effect of hydrogen-bound hydroxyl groups (*H-OH) on the oxidation pathway.
[0051] refer to Figure 3 (Product change curve at 200 mM glycerol concentration in Example 2 over time): Under the condition of 200 mM glycerol concentration, sampling and detection every 2 hours showed that glyceraldehyde was continuously and efficiently generated during the reaction process, further proving that this method can stably inhibit the breakage of CC bonds and achieve targeted conversion of glycerol.
[0052] See also Figure 4 (Electron paramagnetic resonance detection image of the reaction system in Example 2): Electron paramagnetic resonance detection was performed on the reaction system with a glycerol concentration of 200 mM. The results showed the presence of a clear nine peaks (characteristic signals of active hydrogen *H) in the system, directly confirming that titanium dioxide after current activation can efficiently produce active hydrogen. The characteristic *OOH signal was also detected.
[0053] refer to Figure 5(SEM image of the activated TiO2-modified graphite felt cathode after 16 hours of reaction at 200 mM glycerol concentration): It can be clearly seen from the image that nanosphere structures have grown on the TiO2 nanosheets loaded on the electrode surface, and the basic morphology of the TiO2 nanosheets has not been destroyed. This phenomenon directly proves that TiO2 is successfully activated and stably participates in the reaction after high voltage.
[0054] refer to Figure 6 (High-resolution transmission electron microscopy image of the activated TiO2-modified graphite felt cathode after 16 hours of reaction at 200 mM glycerol concentration): The image clearly shows that the nanosphere structure grown on the TiO2 nanosheets has a nanoflower morphology, further revealing the microscopic morphological evolution of TiO2 during the reaction.
[0055] Example 3
[0056] This example uses the activated TiO2-modified graphite felt cathode prepared in Example 1 to directionally catalyze the high-value conversion of glycerol under neutral conditions:
[0057] In a three-electrode system, the activated TiO2-modified graphite felt prepared in Example 1 was used as the cathode, the titanium-based ruthenium-iridium-coated electrode was the anode, and the reference electrode was Ag / AgCl. 50 mmol, 100 mol, 200 mmol, 250 mmol, 300 mmol, and 400 mmol of glycerol (corresponding to a concentration of 50-400 mM) were dissolved in 1000 mL of water, and sodium sulfate (concentration of 100 mmol / L) was added as a supporting electrolyte to form a reaction system (neutral conditions, no acid or base was added after the electrolyte was added to adjust the pH). Oxygen was introduced into the reaction system at a rate of 0.5 liters / minute for 10 minutes, and then a high voltage of -3 V was applied to generate a high current density of approximately 150 mA to carry out the glycerol oxidation reaction.
[0058] The reaction solution was filtered and the product was detected by liquid chromatography. Under the condition of 200 mM glycerol concentration, 400 μL of the reaction solution was taken every 2 hours during the reaction, filtered, and the product changes were analyzed by liquid chromatography.
[0059] At the same time, under the condition of 200 mM glycerol concentration, the high voltage was set to -3 V and the low voltage was set to -1.5 V respectively. After 16 hours of reaction, the reaction liquid was filtered and the product was detected by liquid chromatography to compare the voltage effect.
[0060] refer to Figure 7(Oxidation product distribution map and glycerol aldehyde selectivity curve under different glycerol concentrations in Example 3): After 16h of reaction, the results showed that glycerol aldehyde was produced with high selectivity under different glycerol concentrations, indicating that the hydrogen-bonded hydroxyl (*H-OH) could also achieve precise regulation of the oxidation pathway under neutral conditions.
[0061] Reference Figure 8 (Product change curve over time under 200mM glycerol concentration in Example 3): Under the condition of 200mM glycerol concentration, the sampling and detection every 2h showed that glycerol aldehyde was continuously and efficiently produced during the reaction process, and maintained a selectivity of more than 80%, proving that the method could stably inhibit C-C bond cleavage under neutral conditions, and achieve directional conversion of glycerol.
[0062] Reference Figure 9 (Oxidation product comparison chart under different voltages in Example 3): Under the condition of 200mM glycerol concentration, the product detection results after 16h of high and low voltage reaction showed that only under high voltage (-3V) condition, titanium dioxide could be effectively activated and active hydrogen (*H) was produced, and then hydrogen-bonded hydroxyl (*H-OH) was formed, which promoted the high selective and efficient production of glycerol aldehyde, which confirmed the key role of high voltage in the regulation of active species.
[0063] Reference Figure 10 Solid-state nuclear magnetic resonance test was performed on activated TiO2 modified graphite felt after 16h of reaction at low voltage (-1.5V) and activated TiO2 modified graphite felt after 16h of reaction at high voltage (-3V), respectively, and the results showed that titanium dioxide under high voltage condition was effectively activated and could produce active hydrogen (*H) efficiently, which provided direct evidence for the generation of hydrogen-bonded hydroxyl (*H-OH).
[0064] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any skilled person in the art can make many possible changes and modifications to the technical solutions of the present application, or modify equivalent embodiments, without departing from the spirit and technical solutions of the present application, by using the disclosed methods and technical contents. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments made according to the technical essence of the present application, without departing from the technical solutions of the present application, are still within the scope of protection of the technical solutions of the present application.
Claims
1. A method for efficiently oxidizing glycerol to glyceraldehyde under high potential conditions, characterized in that: A TiO2-modified graphite felt activated by pulse voltage is used as the cathode, forming an electrolysis circuit with the anode. In a reaction system containing glycerol and a supporting electrolyte, a high voltage is applied to generate a large current density, and the active hydrogen *H generated at the cathode combines with the hydroxyl radical ·OH generated in situ by electro-Fenton to form a hydrogen-bound hydroxyl radical *H-OH with moderate oxidative activity, regulating the glycerol oxidation pathway and inhibiting the breakage of the CC bond, thereby achieving highly selective conversion of glycerol to glyceraldehyde.
2. The method according to claim 1, wherein: The TiO2 modified graphite felt activated by pulse voltage is obtained by growing TiO2 nanosheets on the surface of the graphite felt by a hydrothermal method and then applying pulse voltage for activation.
3. The method according to claim 2, wherein: The preparation of the TiO2 modified graphite felt activated by pulse voltage comprises the following steps: S1. Graphite felt surface activation The graphite felt is immersed in a concentrated nitric acid solution and heated in a water bath for surface activation; after activation, it is first washed with ultrapure water until neutral and dried, and then ultrasonically washed in ethanol, acetone, and ultrapure water in sequence to remove surface grease and impurities, and then dried to obtain a surface-activated graphite felt; S2, Growth of TiO2 on graphite felt surface and activation Tetrabutyl titanate, ultrapure water, concentrated hydrochloric acid and ammonium fluorotitanate are mixed to form a precursor solution; the surface-activated graphite felt obtained in step S1 is immersed in the precursor solution and placed in a hydrothermal reactor for a constant-temperature hydrothermal reaction. After the reaction is completed, the graphite felt is washed with acetone and ethanol in sequence, dried and annealed in nitrogen to obtain TiO2-modified graphite felt; the TiO2-modified graphite felt is immersed in an electrolyte solution and activated by applying a pulse voltage to obtain the TiO2-modified graphite felt cathode activated by the pulse voltage.
4. The method according to claim 3, wherein: In step S2, the temperature of the constant temperature hydrothermal reaction is 120-180° C., and the time is 10-16 hours; the temperature of the annealing in nitrogen is 400-600° C., and the time is 1-3 hours.
5. The method according to claim 3, wherein: In step S2, the pulse voltage is a periodically changing rectangular wave with a high potential segment and a low potential segment, wherein the voltage value of the high potential segment is -2V to -4V, the voltage value of the low potential segment is 0V, the electrolysis time is 2-4h, and the duty cycle of the pulse voltage is 70%-90%; when the pulse voltage is applied, a high-purity nickel plate or a platinum plate is used as a counter electrode, and the TiO2-modified graphite felt is used as a working electrode; the pulse voltage drives oxygen vacancies and TiO2 in the high potential segment. 3+ Active sites are generated to stabilize the titanium dioxide structure in the low potential range.
6. The method according to claim 3, wherein: In step S2, the electrolyte in the electrolyte solution is sodium sulfate, potassium sulfate, sodium perchlorate, or a mixture of sodium sulfate and sodium bisulfate.
7. The method according to claim 1, wherein: The high voltage is -2.5V to -4V, and the high current density formed is 100-400 mA.
8. The method according to claim 1, wherein: Before applying high voltage to carry out the reaction, oxygen is introduced into the reaction system to saturate the reaction system with oxygen.
9. The method according to claim 1, wherein: The glycerol oxidation reaction is carried out under acidic to neutral conditions; when the system is acidic, ferrous salt is added to the system.
10. The method according to claim 1, characterized in that The supporting electrolyte is sodium sulfate, potassium sulfate, sodium perchlorate, or a mixture of sodium sulfate and sodium bisulfate; the anode is a titanium-based ruthenium-iridium coating electrode, a boron-doped diamond electrode, or a platinum electrode.