Carbon-supported electron-rich phenolic resin electrocatalyst and method for preparing the same

Abstract

The application belongs to the technical field of electrocatalyst preparation, and discloses a carbon-supported electron-rich phenolic resin electrocatalyst and a preparation method thereof. The electrocatalyst is obtained by in-situ condensation reaction of a phenolic monomer and an aldehyde-containing heterocyclic monomer on the basis of a conductive carbon material as a carrier. The application has the following beneficial effects: a series of efficient electrocatalysts are obtained by in-situ condensation of different phenolic monomers on the carbon material carrier, the obtained polymers have clear connecting units, the structure units can be adjusted at the molecular level to regulate the overall physicochemical properties of the material, and finally the excellent electrocatalytic performance is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalyst preparation, and particularly relates to a carbon-loaded electron-rich phenolic resin electrocatalyst and a preparation method thereof. BACKGROUND

[0002] Traditional electrocatalysts such as platinum (Pt), iridium (lr), ruthenium (Ru), palladium (Pd) and rhodium (Rh) and other noble metal-based nanomaterials play an important role in various catalytic reactions. However, due to the low crust abundance and high price of these noble metals, their wide application is limited. Metal-free catalysts have potential value and application in various electrochemical reactions, and the possibility of replacing various noble metal catalysts. The development of metal-free catalysts aims to solve the problems of high cost and limited resources of noble metal catalysts, while realizing efficient and stable catalytic performance.

[0003] Among them, carbon-based metal-free electrocatalysts are usually made of biomass or polymer-derived carbon materials, which are widely available, low in price, and have good environmental compatibility. And can be regulated by heteroatom doping (such as N, S, etc.), defect introduction and surface functionalization strategies, so as to realize the optimization of catalytic activity and selectivity for specific reactions. However, the existing metal-free catalyst preparation technology is mostly based on the pyrolysis of materials, or is subjected to complex synthesis and post-processing processes, and the activity regulation range of the materials is narrow, which is limited in the selection of reactants. SUMMARY

[0004] The purpose of the present application is to provide a method that is simple, highly feasible, and has a wide range of material activity regulation, to prepare efficient metal-free electrocatalysts. In view of the above shortcomings of the prior art, a carbon-loaded electron-rich phenolic resin electrocatalyst and a preparation method thereof are proposed.

[0005] A carbon-loaded electron-rich phenolic resin electrocatalyst, in which a conductive carbon material is used as a carrier, and an electron-rich phenolic resin is loaded on the surface of the carrier.

[0006] The above technical solution can be further provided as: the electron-rich phenolic resin is obtained by in-situ condensation reaction of a phenolic monomer and an aldehyde group-containing heterocyclic monomer.

[0007] The above technical solution can be further provided as: the conductive carbon material is one or more of carbon nanotubes, graphene, graphite, carbon black, carbon fiber, acetylene black, and graphdiyne.

[0008] The above technical solution can be further provided as: the surface of the conductive carbon material is subjected to hydroxylation or oxidation pretreatment.

[0009] By adopting the technical scheme, the surface of the conductive carbon material is subjected to functionalization pretreatment, the carbon nanotube is a hydroxylated carbon nanotube, and the graphene is surface oxygen-rich functional group graphene. The surface functionalization pretreatment can improve the hydrophilicity of the material, enable the carbon nanotube to be better dispersed in a polar solvent, and can enhance the interaction force with the reaction monomer.

[0010] The technical scheme can be further provided that the phenolic monomer includes one or more of phenol, resorcinol, phloroglucinol, 2-naphthol, 2,3-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 5-chlororesorcinol, 3-chlorophenol, 3,5-dichlorophenol, 4-methoxyphenol, 4-methylphenol, 4-iodophenol, 4-chlorophenol, 4-bromophenol, 4-hydroxythiophenol, 4-aminophenol, and 4-nitrophenol.

[0011] The technical scheme can be further provided that the aldehyde group-containing heterocyclic monomer includes one or more of 2-pyrrolecarboxaldehyde, 2-furan carboxaldehyde, 2-thiophene carboxaldehyde, 1H-pyrazole-3-carboxaldehyde, 4-imidazole carboxaldehyde, oxazole-5-carboxaldehyde, and 5-thiazole carboxaldehyde.

[0012] The technical scheme can be further provided that the molar ratio of the phenolic monomer and the aldehyde group-containing heterocyclic monomer is 1:2-1:2.5.

[0013] The preparation method of the carbon-loaded electron-rich phenolic resin electrocatalyst includes the following steps:

[0014] S1, dispersing the conductive carbon material and the phenolic monomer in an equal proportion of ethanol and water solvent, ultrasonic dispersion, then adding the aldehyde group-containing heterocyclic monomer to the mixed solution, and continuing ultrasonic dispersion;

[0015] S2, adding an alkali solution to the mixed solution of step S1, and reacting at 40-80℃ and 200-400rpm for 8-12h;

[0016] S3, subjecting the reaction solution obtained in step S2 to hydrothermal reaction to obtain the target metal-free catalyst.

[0017] The technical scheme can be further provided that the alkali solution is one of NH3•H2O, sodium hydroxide, or sodium carbonate.

[0018] The technical scheme can be further provided that: ethanol and water are used as a kind of polar reaction solvent, which can ensure the sufficient dissolution of the reaction monomer and indirectly participate in the reaction process. In addition, compared with other organic solvents, the mixed solvent of ethanol and water is more environmentally friendly, which is conducive to reducing costs and reducing environmental pollution.

[0019] NH3•H2O is used as a catalyst to participate in the reaction process, and sodium hydroxide or sodium carbonate can be used as a substitute.

[0020] The technical solution can be further provided that the hydrothermal reaction condition of the step S3 is 150-250℃ for 12-36h.

[0021] Beneficial effects:

[0022] 1. The present application obtains a series of efficient electrocatalysts by in-situ condensation of selected different phenolic monomers on a carbon material carrier. The obtained polymers have clear connection units, and the structure units can be adjusted at the molecular level to regulate the overall physicochemical properties of the material, and finally achieve excellent electrocatalytic performance.

[0023] 2. By condensing different types of phenolic monomers, the electronic properties of the material locally and as a whole are regulated, thereby affecting the adsorption behavior between the reaction molecules and the material in the catalytic process, and the optimal reaction kinetics and thermodynamics can be achieved. Moreover, the related strength and type of the synergistic effect between the phenolic monomers can be realized at the molecular level design, and by adjusting the types and amounts of functional groups, the differential control of the material can be achieved.

[0024] 3. The special core-shell structure obtained by combining the electron-rich phenolic resin with the conductive carbon material has a special morphology structure, such as the one-dimensional tubular structure of carbon nanotubes and the two-dimensional planar structure of graphene, which has a larger specific surface area in space. After loading the polymer on the surface, the obtained catalytic material also has the morphology characteristics of the carrier, which is beneficial to the exposure of active sites. The high electrical conductivity of the conductive carbon material itself is beneficial to the electron transfer of the material during the reaction process and is beneficial to the catalytic process kinetics.

[0025] 4. The existing synthesis method of electrocatalysts is generally complicated and mostly contains metal materials. The synthesis method of the present application is simple, does not add metal, and has strong universality. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The reaction flow for the conductive carbon loaded phenolic polymer.

[0027] Figure 2 The transmission electron microscopy (TEM) image of the carbon nanotube / resorcinol-thiophene type catalyst.

[0028] Figure 3 The oxygen reduction electrocatalytic test results of 2 carbon nanotubes (CNT) / resorcinol-thiophene formaldehyde and resorcinol-thiophene formaldehyde.

[0029] Figure 4 The oxygen reduction electrocatalytic test results of resorcinol-thiophene type catalyst and resorcinol-furfuraldehyde type catalyst.

[0030] Figure 5The results of the oxygen reduction electrocatalysis tests for carbon nanotube (CNT) / resorcinol-thiophene type catalyst and carbon nanotube (CNT) / resorcinol-furfuraldehyde type catalyst. DETAILED DESCRIPTION

[0031] The following are specific embodiments of the present application and further describe the technical solutions of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0032] Example 1 Carbon nanotube / resorcinol-furan type catalyst

[0033] Pre-surface-hydroxylated carbon nanotubes (CNT, 30 mg) and resorcinol (50 mg, 0.4 mmol) were dispersed in an equal proportion of ethanol and water (10 ml, 10 ml) solvent, and ultrasonic dispersion was performed for 1 hour, after which 2-furfuraldehyde (77 mg, 0.8 mmol) was added to the mixture, and ultrasonic dispersion was continued for 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture, and reaction was performed at 50°C and 300 rpm for 10 hours, after which the reaction solution was transferred to a 50 ml hydrothermal reactor, and reaction was continued at 200°C for 24 hours, and the resulting product was the target metal-free catalyst.

[0034] Example 2 Graphene / resorcinol-pyrrole type catalyst

[0035] Surface oxygen-rich functional group graphene (rGO, 30 mg) and resorcinol (44 mg, 0.4 mmol) were dispersed in an equal proportion of ethanol and water (10 ml, 10 ml) solvent, and ultrasonic dispersion was performed for 1 hour, after which 2-pyrrole formaldehyde (76 mg, 0.8 mmol) was added to the mixture, and ultrasonic dispersion was continued for 1 hour. 30% NaOH (0.5 ml) was added to the mixture, and reaction was performed at 70°C and 400 rpm for 12 hours, after which the reaction solution was transferred to a 50 ml hydrothermal reactor, and reaction was continued at 230°C for 24 hours, and the resulting product was the target metal-free catalyst.

[0036] Example 3 Carbon nanotube / resorcinol-thiophene type catalyst

[0037] Pre-surface-hydroxylated carbon nanotubes (CNT, 30 mg) were dispersed with 4- bromophenol (50 mg, 0.4 mmol) in an equal proportion of ethanol and water (10 ml, 10 ml) solvent and ultrasonically dispersed for 1 hour, after which 2-furancarboxaldehyde (77 mg, 0.8 mmol) was added to the mixture and ultrasonically dispersed for 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture, which was reacted at 70°C and 400 rpm for 12 hours, after which the reaction solution was transferred to a 50-ml hydrothermal reaction kettle and reacted at 250°C for 36 hours. The resulting product was the target metal-free catalyst.

[0038] Example 4 Graphdiyne / p-bromophenol-furan-type catalyst

[0039] Surface-functionalized MXenes (30 mg) were dispersed with p-bromophenol (69 mg, 0.4 mmol) in an equal proportion of ethanol and water (10 ml, 10 ml) solvent and ultrasonically dispersed for 1 hour, after which 2-furancarboxaldehyde (77 mg, 0.8 mmol) was added to the mixture and ultrasonically dispersed for 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture, which was reacted at 70°C and 400 rpm for 12 hours, after which the reaction solution was transferred to a 50-ml hydrothermal reaction kettle and reacted at 250°C for 36 hours. The resulting product was the target metal-free catalyst.

[0040] Example 5 Carbon fiber / m-trihydroxybenzene-pyrazole-type catalyst

[0041] Carbon fiber (30 mg) was dispersed with m-trihydroxybenzene (50 mg, 0.4 mmol) in an equal proportion of ethanol and water (10 ml, 10 ml) solvent and ultrasonically dispersed for 1 hour, after which 1H-pyrazole-5-carboxaldehyde (77 mg, 0.8 mmol) was added to the mixture and ultrasonically dispersed for 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture, which was reacted at 40°C and 200 rpm for 12 hours, after which the reaction solution was transferred to a 50-ml hydrothermal reaction kettle and reacted at 160°C for 12 hours. The resulting product was the target metal-free catalyst.

[0042] Example 6 Acetylene black / p-methylphenol-oxazole-type catalyst

[0043] Pre-surface functionalized acetylene black (30 mg) was dispersed in equal proportion of ethanol and water (10 ml, 10 ml) solvent with p-methylphenol (43 mg, 0.4 mmol) and sonicated for 1 hour. Oxazole-5-carboxaldehyde (78 mg, 0.8 mmol) was added to the mixture and sonicated for another 1 hour. 50% Na2CO3(0.6 ml) was added to the mixture and reacted at 50 °C with 300 rpm for 10 hours. The reaction solution was transferred to a 50 ml hydrothermal reactor and reacted at 150 °C for 20 hours. The resulting product was the target metal-free catalyst.

[0044] Example 72 Carbon nanotube / resorcinol-thiophene type catalyst

[0045] Pre-surface hydroxylated carbon nanotube (CNT, 200 mg) was dispersed in equal proportion of ethanol and water (10 ml, 10 ml) solvent with resorcinol (100 mg, 0.8 mmol) and sonicated for 1 hour. 2-Thiophene carboxaldehyde (180 mg, 1.6 mmol) was added to the mixture and sonicated for another 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture and reacted at 80 °C with 300 rpm for 10 hours. The reaction solution was transferred to a 50 ml hydrothermal reactor and reacted at 250 °C for 24 hours. The resulting product was the target metal-free catalyst.

[0046] Comparative Example 1 Resorcinol-thiophene type catalyst

[0047] Resorcinol (50 mg, 0.4 mmol) was dispersed in equal proportion of ethanol and water (10 ml, 10 ml) solvent and sonicated for 1 hour. 2-Thiophene carboxaldehyde (90 mg, 0.8 mmol) was added to the mixture and sonicated for another 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture and reacted at 80 °C with 300 rpm for 10 hours. The reaction solution was transferred to a 50 ml hydrothermal reactor and reacted at 250 °C for 24 hours. The resulting product was the target metal-free catalyst.

[0048] Comparative Example 2 Resorcinol-furfural type catalyst

[0049] Phloroglucinol (50 mg, 0.4 mmol) was dispersed in an equal proportion of ethanol and water (10 ml, 10 ml) solvent, and ultrasonic dispersion was performed for 1 hour, after which 2-furfuryl aldehyde (77 mg, 0.8 mmol) was added to the mixture, and ultrasonic dispersion was continued for 1 hour. 37 wt% NH3•H2O (0.7 ml) was added to the mixture, and reaction was performed at 80°C and 300 rpm for 10 hours, after which the reaction solution was transferred to a 50 ml hydrothermal reactor, and reaction was continued at 250°C for 24 hours, and the resulting product was the target metal-free catalyst.

[0050] Experimental data

[0051] The metal-free catalyst obtained in Example 3 was subjected to transmission electron microscopy testing, and the transmission electron microscopy image is shown in Figure 2 From Figure 2 it can be seen that the phloroglucinol and thiophene formaldehyde condensation polymer is loaded on the carbon nanotube, and it can be found that the final product has a one-dimensional core-shell structure.

[0052] The metal-free catalysts obtained in Example 7 2 carbon nanotube / phloroglucinol-thiophene type catalyst and Comparative Example 1 phloroglucinol-thiophene type catalyst were subjected to oxygen reduction electrocatalysis testing, and the testing method was linear sweep voltammetry, and the testing results are as follows Figure 3 From Figure 3 it can be seen that the introduction of carbon nanotubes significantly enhances the limiting current density of the material, speeds up the overall electron transfer of the material, and the half-wave potential of the catalyst curve with the addition of carbon nanotubes is significantly more positive, indicating that the introduction of carbon nanotubes enhances the catalytic activity and kinetics of the reaction in the oxygen reduction reaction.

[0053] The metal-free catalysts obtained in Comparative Example 1 phloroglucinol-thiophene type catalyst and Comparative Example 2 phloroglucinol-furfuryl aldehyde type catalyst were subjected to oxygen reduction electrocatalysis testing, and the testing method was linear sweep voltammetry, and the testing results are as follows Figure 4 From Figure 4 it can be seen that the phloroglucinol-furfuryl aldehyde type polymer has a greater limiting current density and a more positive half-wave potential, indicating that changing the type of polymer monomer can effectively improve the catalytic activity of the material in the catalytic reaction.

[0054] Example 1 carbon nanotube / phloroglucinol-furfuryl type catalyst and Example 3 carbon nanotube / phloroglucinol-thiophene type catalyst were subjected to oxygen reduction electrocatalysis testing, and the testing results are as follows Figure 5 From Figure 5It can be seen that, in the case of changing the polymer monomer type and adding the same proportion of carbon nanotubes, the carbon nanotube / phloroglucinol-thiophene type catalyst has a more correct half-wave potential and limiting current density, indicating that the condensed thiophene polymer has more excellent electrocatalytic activity than the furan polymer under the same carrier conditions.

[0055] Comparison Figure 4 and Figure 5 It can be seen that the introduction of carbon nanotubes can further expand the performance difference between the phloroglucinol-furan type catalyst and the phloroglucinol-thiophene type catalyst.

[0056] By different monomer combinations in condensation reactions, differences in polymer structure units can be achieved, which changes the overall properties of the material. This change will affect the adsorption characteristics of the material to the reaction molecules, so that according to different needs, the best condensation reaction combination is selected, so that the electrocatalytic reaction has the most appropriate overpotential, thereby having the most optimal reaction activity.

[0057] The above matters not covered are applicable to the prior art.

[0058] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, but will not deviate from the direction of the present application or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modification, equivalent replacement, improvement, etc. made according to the technical essence of the present application to the above embodiments shall be included in the protection scope of the present application.

Claims

1. A carbon-supported electron-rich phenolic resin electrocatalyst, characterized by: The conductive carbon material is used as a carrier, and an electron-rich phenolic resin is loaded on the surface of the carrier; The electron-rich phenolic resin is obtained by in-situ condensation reaction of a phenolic monomer and an aldehyde-containing heterocyclic monomer; The surface of the conductive carbon material is pretreated by hydroxylation or oxidation; The phenolic monomer is one or more of phenol, resorcinol, phloroglucinol, 2-naphthol, 2,3-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 5-chlororesorcinol, 3-chlorophenol, 3,5-dichlorophenol, 4-methoxyphenol, 4-methylphenol, 4-iodophenol, 4-chlorophenol, 4-bromophenol, 4-hydroxythiophenol, 4-aminophenol, and 4-nitrophenol; The aldehyde-containing heterocyclic monomer is one or more of 2-pyrrolecarboxaldehyde, 2-furan carboxaldehyde, 2-thiophene carboxaldehyde, 1H-pyrazole-3-carboxaldehyde, 4-imidazole carboxaldehyde, oxazole-5-carboxaldehyde, and 5-thiazole carboxaldehyde; A preparation method of the carbon-loaded electron-rich phenolic resin electrocatalyst, comprising the following steps S1, dispersing the conductive carbon material and the phenolic monomer in equal volumes of ethanol and water solvent, ultrasonic dispersion, then adding the aldehyde-containing heterocyclic monomer to the mixed solution, and continuing ultrasonic dispersion; S2, adding an alkali solution to the mixed solution of step S1, and reacting at 40-80℃ and 200-400rpm for 8-12h; S3, performing hydrothermal reaction on the reaction solution obtained in step S2 to obtain the target catalyst; The hydrothermal reaction condition is 150-250℃ for 12-36h.

2. The carbon-supported electrophilic phenolic resin electrocatalyst of claim 1, wherein: The conductive carbon material is one or more of carbon nanotubes, graphene, graphite, carbon black, carbon fiber, acetylene black, and graphyne.

3. The carbon-supported electrophilic phenolic resin electrocatalyst of claim 1, wherein: The molar ratio of the phenolic monomer to the aldehyde-containing heterocyclic monomer is 1:2-1:2.

5.

4. The process for the preparation of carbon supported electron-rich phenolic resin electrocatalysts according to any one of claims 1 to 3, characterized in that, comprising the following steps S1, dispersing the conductive carbon material and the phenolic monomer in equal volumes of ethanol and water solvent, ultrasonic dispersion, then adding the aldehyde-containing heterocyclic monomer to the mixed solution, and continuing ultrasonic dispersion; S2, adding an alkali solution to the mixed solution of step S1, and reacting at 40-80℃ and 200-400rpm for 8-12h; S3, performing hydrothermal reaction on the reaction solution obtained in step S2 to obtain the target catalyst; The hydrothermal reaction condition is 150-250℃ for 12-36h.

5. The method for preparing the carbon-supported electron-rich phenolic resin electrocatalyst according to claim 4, characterized in that: The alkali solution is one of NH3•H2O, sodium hydroxide, or sodium carbonate.

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