Carbon dioxide-derived porous carbon material with improved performance by polymer treatment and electrochemical method of producing hydrogen peroxide using same

Abstract

The present invention relates to a carbon dioxide-derived porous carbon material with improved performance by polymer treatment and an efficient electrochemical method of producing hydrogen peroxide using same. More specifically, the present invention includes a porous carbon material synthesis method wherein carbon dioxide-containing exhaust gas or production-process waste gas is converted into porous carbon by reaction with a reducing agent containing boron, and an oxygen functional group is further introduced by heat treatment with a polymer containing the oxygen functional group.

Description

Carbon dioxide-derived porous carbon material with improved performance through polymer treatment and electrochemical method for producing hydrogen peroxide using the same

[0001] The present invention relates to a porous carbon material derived from carbon dioxide with improved performance through polymer treatment and an electrochemical method for producing hydrogen peroxide using the same, and more specifically, to a porous carbon material derived from carbon dioxide with improved performance through polymer treatment that can be used as a catalyst for electrochemical production of hydrogen peroxide by reacting exhaust gas or production process waste gas containing carbon dioxide with a reducing agent containing boron and heat-treating the material with a polymer containing oxygen functional groups to introduce oxygen functional groups.

[0002]

[0003] Hydrogen peroxide is an environmentally friendly oxidizing agent. Its large-scale production and rapid market growth have led to its widespread use in various fields, including wastewater treatment, semiconductors, and medicine. Currently, hydrogen peroxide is produced on a large scale in industry through hydrogenation and oxidation reactions, primarily via the anthraquinone process. However, this method has drawbacks, including excessive energy consumption, the use of expensive palladium catalysts, complex reprocessing procedures, and environmental concerns due to chemical waste. As an alternative, there is a method for directly synthesizing hydrogen peroxide, but this involves a partially explosive process and requires the use of expensive precious metal catalysts. As an alternative to these two methods for hydrogen peroxide synthesis, the two-electron oxygen reduction reaction (2e) has been proposed. - An electrochemical synthesis method using the two-electron oxygen reduction reaction (ORR) has been proposed. This method has the advantages of being environmentally friendly as it does not produce byproducts or organic waste, consuming less energy, and not posing a risk of explosion. The reaction equation for the two-electron oxygen reduction reaction is as follows.

[0004] O2+ 2 (H + + e - ) → OOH * + (H + + e - ) → H2O2

[0005]

[0006] Precious metals such as Pd, Au, and Pt-Hg are used as catalysts in the two-electron oxygen reduction reaction to increase activity, but their high cost limits mass production. As an alternative, carbon-based materials are attracting attention as catalysts for the oxygen reduction reaction. Carbon-based catalysts have fewer side reactions and high cycle characteristics than metal-based catalysts, and are cheaper than non-precious metal-based materials, which makes them advantageous for mass production. However, the catalytic activity of carbon materials themselves is low, so active research is being conducted to improve activity by doping with heterogeneous elements such as boron, nitrogen, oxygen, fluorine, phosphorus, and sulfur. In particular, the introduction of oxygen functional groups can improve the hydrogen peroxide selectivity of carbon-based materials for electrochemical hydrogen peroxide synthesis (A. Byeon et al, ChemElectroChem, 2023, 10, e202300234).

[0007]

[0008] Among the electrocatalysts used in the two-electron oxygen reduction reaction, various studies on homogeneous catalysts are being conducted, and among them, metal phthalocyanines are synthetic analogs of naturally occurring porphyrins, and when utilized as single-atom catalysts, they have shown high catalytic activity. The central metal ion coordinated to the four isoindole subunits of phthalocyanines contributes to this activity, and in particular, metal phthalocyanines (MPCs), such as iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc), have shown promising results as two-electron oxygen reduction electrocatalysts (WJ Zhang et al., Appl. Catal. B: Environ., 2023, 331, 122712). However, metal phthalocyanines tend to deteriorate electrochemical performance by reducing active sites and hindering electron transfer due to aggregation, and further research is needed on strategies such as better dispersion techniques or appropriate supports to alleviate aggregation (S. Yang. et al., Chem. Soc. Rev., 2021,50, 12985-13011).

[0009]

[0010] As a result of efforts to solve the above problems, the present inventors have manufactured a catalyst by introducing oxygen functional groups into a porous carbon material derived from carbon dioxide having a large surface area by heat-treating it with a polymer containing oxygen functional groups, such as polyethylene oxide, and then further dispersing and adsorbing a small amount of cobalt phthalocyanine molecules in a single form, and have confirmed that the catalyst exhibits excellent performance in the electrochemical production of hydrogen peroxide by utilizing the synergistic effect of the oxygen functional groups and / or single-atom structures introduced into the micro- and meso-porous structures in a simple manner under atmospheric pressure conditions, thereby completing the present invention.

[0011]

[0012] This invention was carried out with the support of the national project (50% contribution) titled “Distributed Low-Carbon Hydrogen Production Research Center (2024)” and the Artificial Photosynthesis Research Institute Co., Ltd. project (50% contribution) titled “Research on Artificial Photosynthesis Technology (APLAB-2024-02) (2024)” of the 1st year (2024).

[0013]

[0014] The purpose of the present invention is to provide a method for producing a porous carbon material derived from carbon dioxide with improved performance through polymer treatment and a method for producing electrochemical hydrogen peroxide using a catalyst utilizing the carbon material produced by the method.

[0015]

[0016] To achieve the above object, the present invention provides a method for producing a boron-doped carbon dioxide-derived porous carbon material, comprising the steps of (a) reacting a reducing agent containing boron with a carbon dioxide-containing gas to obtain a porous solid product; and (b) heat-treating the porous carbon material with a polymer containing an oxygen functional group to obtain a porous carbon material into which an oxygen functional group has been introduced.

[0017] The present invention is manufactured by the above method, and has a BET surface area of ​​400-500 m 2 / g, mesopore volume is 0.5-1.0cm 3 / g, micropore volume is 0.1-0.2cm 3 / g is provided as a porous carbon material derived from carbon dioxide doped with boron.

[0018] The present invention is manufactured by the above method, and has a BET surface area of ​​900-1000 m 2 / g, mesopore volume is 2.0-3.0cm 3 / g, micropore volume is 0.01-0.3cm 3 / g is provided as a porous carbon material derived from carbon dioxide doped with boron.

[0019] The present invention is manufactured by the above method, and 0.05 to 10 parts by weight of metal phthalocyanine is adsorbed based on 100 parts by weight of carbon material, and I indicates the degree of structural development of the carbon material by Raman analysis. D / I G A porous carbon material derived from boron-doped carbon dioxide characterized by a value of 0.7 to 1 through polymer treatment and cobalt phthalocyanine adsorption is provided.

[0020] The present invention provides an electrochemical method for producing hydrogen peroxide by producing H2O2 from O2 using the porous carbon material derived from carbon dioxide doped with boron.

[0021]

[0022] The hierarchical porous carbon material synthesized using carbon dioxide as a raw material according to the present invention provides an eco-friendly and energy-saving economical process by forming a single-atom catalyst through polymer treatment under atmospheric pressure conditions and simple ultrasonic treatment rather than a supercritical process.

[0023] These materials possess hierarchical micropores and mesopores, and can be used to catalyze the two-electron oxygen reduction reaction (ORR) due to the synergistic effect of doped oxygen functional groups and adsorbed single-atom structures, achieved through simple polymer heat treatment. These materials hold promising potential as replacements for expensive palladium catalysts.

[0024]

[0025] Figure 1 is a flowchart showing the steps for manufacturing a hierarchical porous carbon material derived from carbon dioxide according to Example 1 of the present invention.

[0026] Figure 2 is a flowchart showing the steps for manufacturing a porous carbon material doped with boron according to Example 2 of the present invention.

[0027] Figure 3 is a flowchart showing the steps for manufacturing a porous carbon material with an oxygen functional group introduced using a polymer according to Example 2 of the present invention.

[0028] Figure 4 is a flowchart showing the steps for manufacturing a hierarchical porous carbon material with an oxygen functional group introduced using a polymer according to Example 3 of the present invention.

[0029] FIG. 5 is a flowchart showing the steps for manufacturing a hierarchical porous carbon material into which a cobalt single-atom catalyst is introduced according to Example 4 of the present invention.

[0030] Figure 6 is a flowchart showing the steps for manufacturing a porous carbon material by heat-treating a polymer without an oxygen functional group according to Example 5 of the present invention.

[0031] Figure 7 is an SEM photograph of a porous carbon material derived from carbon dioxide obtained in Examples 2 and 5 of the present invention.

[0032] Figure 8 is an SEM photograph of a hierarchical porous carbon material derived from carbon dioxide obtained in Example 1 and Examples 3-4 of the present invention.

[0033] Figure 9 is a STEM dark field mode photograph of a cobalt single-atom catalyst adsorbed on a hierarchical porous carbon material obtained in Example 4 of the present invention.

[0034] Figure 10 is a TEM EDS photograph of a cobalt single-atom catalyst adsorbed on a hierarchical porous carbon material obtained in Example 4 of the present invention.

[0035] Figure 11 shows the XRD analysis results of the porous carbon material obtained in Example 1-5 of the present invention.

[0036] Figure 12 shows nitrogen adsorption / desorption isotherm curves and BET surface area results of the porous carbon material obtained in Example 1-5 of the present invention.

[0037] Figure 13 is an NLDFT result for the distribution of micropores of porous carbon materials obtained in Examples 2 and 5 of the present invention.

[0038] Figure 14 is an NLDFT result for the distribution of micropores of porous carbon materials obtained in Example 1 and Examples 3-4 of the present invention.

[0039] Figure 15 shows the XPS results and element ratio results of the porous carbon material obtained in Example 1-5 of the present invention.

[0040] Figure 16 is an XPS result for the form of boron bonds in porous carbon materials obtained in Examples 2 and 5 of the present invention.

[0041] Figure 17 is an XPS result for the form of oxygen bonding in the hierarchical porous carbon material obtained in Example 1 and Examples 3-4 of the present invention.

[0042] Figure 18 shows the results of Raman analysis of carbon materials obtained in Example 1 and Examples 3-4 of the present invention.

[0043] Figure 19 shows the results of current-potential curves and selectivity of hydrogen peroxide in an oxygen reduction reaction by linear cyclic voltammetry (LSV) in a basic electrolyte using a hierarchical porous carbon material according to Example 1-5 of the present invention as an electrode.

[0044] Figure 20 shows the results of current potential curves and selectivity of hydrogen peroxide in an oxygen reduction reaction by linear cyclic voltammetry (LSV) in a neutral electrolyte using hierarchical porous carbon materials according to Examples 1 and 3-4 of the present invention as electrodes.

[0045] Figure 21 shows the results of current potential curves and selectivity of hydrogen peroxide in an oxygen reduction reaction by linear cyclic voltammetry (LSV) in an acidic electrolyte using hierarchical porous carbon materials according to Examples 1 and 3-4 of the present invention as electrodes.

[0046] Figure 22 is a photograph of an H-type cell composed of two chambers for evaluating an oxygen reduction reaction in a basic electrolyte using the porous carbon material of the present invention as an electrode.

[0047] FIG. 23 shows the results of a chronoamperometry (CA) curve and Faraday efficiency and concentration of generated hydrogen peroxide at 4 hours through analysis of an H-type cell in a basic electrolyte using a porous carbon material as an electrode according to Example 2 of the present invention.

[0048] Figure 24 shows UV-Vis absorption spectra of various Ce(SO4)2 concentrations in 0.5 M H2SO4 solution for H-type cell analysis of porous carbon material according to Example 2 of the present invention and various Ce at a wavelength of 320 nm. 4+ This is the result of absorbance of concentration.

[0049] FIG. 25 shows the results of the Faraday efficiency of hydrogen peroxide synthesis at each hourly interval, the amount of hydrogen peroxide produced, and the hydrogen peroxide production rate when 0.4 V vs. RHE was applied in an H-type cell analysis for 4 hours in a basic electrolyte using a porous carbon material as an electrode according to Example 2 of the present invention.

[0050] FIG. 26 shows the results of a chronoamperometry (CA) curve and the faradaic efficiency and concentration of hydrogen peroxide generated at 18 hours through analysis of an H-type cell in a basic electrolyte using a porous carbon material as an electrode according to Example 2 of the present invention.

[0051] FIG. 27 shows the results of the hydrogen peroxide production rate for 12 hours when 0.3 V vs. RHE was applied in an H-type cell analysis for 12 hours in a neutral electrolyte using a hierarchical porous carbon material as an electrode according to Example 4 of the present invention.

[0052]

[0053] Specific details for carrying out the invention

[0054] All technical and scientific terms used herein, unless specifically defined otherwise, have the same meaning as would be commonly understood by a skilled practitioner in the art to which the present invention pertains. Furthermore, the nomenclature of terms used herein is widely known and commonly used in the art.

[0055]

[0056] The present invention provides a porous solid product obtained by reacting a reducing agent containing boron with a carbon dioxide-containing gas, heat-treating the porous solid product with a polymer containing an oxygen functional group such as polyethylene oxide, and using cobalt phthalocyanine molecule adsorption to produce a carbon dioxide-based hierarchical porous carbon material, whereby micropores and mesopores exist hierarchically and the polymer treatment results in a synergistic effect between the doped oxygen functional group and the monoatomic structure adsorbed thereon, thereby confirming that the porous solid product can be utilized to catalyze a two-electron oxygen reduction reaction.

[0057] Accordingly, the present invention relates to a method for producing a boron-doped carbon dioxide-derived porous carbon material, comprising, in one aspect, the steps of (a) reacting a reducing agent containing boron with a carbon dioxide-containing gas to obtain a porous solid product; and (b) heat-treating the porous carbon material with a polymer containing an oxygen functional group to obtain a porous carbon material into which an oxygen functional group has been introduced.

[0058]

[0059] Hereinafter, the process of the present invention will be described in detail.

[0060] One embodiment of the present invention provides a method for producing a cobalt single-atom catalyst using a carbon dioxide-derived porous carbon material with improved performance through polymer treatment, comprising the steps of mixing a catalyst and a carbon raw material to produce a mixture and heating the mixture in a carbon dioxide or inert gas environment.

[0061] The present invention provides a method for producing a carbon dioxide-based hierarchical porous carbon material using polyethylene oxide polymer treatment and cobalt phthalocyanine adsorption. This carbon material can be used as a catalyst for a two-electron oxygen reduction reaction, and has been confirmed to exhibit excellent performance as an electrochemical material.

[0062]

[0063] The present invention manufactures a porous carbon material derived from carbon dioxide doped with boron by the steps of (a) reacting a reducing agent containing boron with a carbon dioxide-containing gas to obtain a porous solid product; and (b) heat-treating the porous carbon material with a polymer containing an oxygen functional group to obtain a porous carbon material into which an oxygen functional group has been introduced.

[0064] In the present invention, a step of adding a nano-mold to a reducing agent may be additionally included before the step (a), wherein the nano-mold used in the reduction reaction may be in the form of a transition metal, an alkali metal, an alkaline earth metal or a noble metal, and may be an oxide (MetalxOy), carbonate (Metalx(CO3)) thereof. y ), or may be in the form of chloride, etc. The transition metal may be nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), titanium (Ti), iron (Fe), or manganese (Mn), the alkali metal may be lithium (Li), sodium (Na), or cesium (Cs), the alkaline earth metal may be magnesium (Mg), calcium (Ca), or strontium (Sr), and the precious metal may be gold (Au), platinum (Pt), or silver (Ag).

[0065] In the present invention, the nano mold is CaO, MgO, Fe2O3, Fe3O4, CaCO 3, Na2CO 3, It is preferable to select at least one from the group consisting of NiCO3, CoCO3, Li2CO3, and FeCO3.

[0066] In the present invention, the polymer including an oxygen functional group may be at least one selected from the group consisting of polyethylene oxide, polypropylene glycol, polyoxymethylene, polycarbonate, and polycarprolactone, and polyethylene oxide is preferably used, but is not limited thereto.

[0067] In the present invention, a step of dispersing and adsorbing a cobalt phthalocyanine metal catalyst may be additionally included after step (b).

[0068] In the present invention, a step of washing and drying the porous carbon material may be additionally included after step (b).

[0069] In the present invention, the reducing agent containing boron may be selected from the group consisting of boron oxide (B2O3), boric acid (H3BO3), lithium boron hydride (LiBH4), sodium boron hydride (NaBH4), potassium boron hydride (KBH4), magnesium boron hydride (Mg(BH4)2), calcium boron hydride (Ca(BH4)2), strontium boron hydride (Sr(BH4)2), sodium detraborate (Na2B4O5(OH)48H2O), and barium tetraborate (BaB2O4), but is not limited thereto.

[0070]

[0071] A method for manufacturing a hierarchical porous carbon material according to a preferred embodiment of the present invention may include a heat treatment step of physically mixing a reducing agent with a nano-mold having a size of several nanometers to several hundred nanometers and then reacting it with a gas containing carbon dioxide (hereinafter, step 1 manufacturing method).

[0072] In the present invention, after the first manufacturing process, a step of continuously performing heat treatment under inert gas conditions may be included (hereinafter, the second manufacturing method).

[0073] In the present invention, a step of performing heat treatment under inert gas conditions after physical mixing with a polymer after the continuous manufacturing method may be included (hereinafter, a three-step manufacturing method).

[0074] In the present invention, after the continuous manufacturing method, an ultrasonic treatment and freeze drying step under inert gas conditions for adsorbing metal phthalocyanine molecules may be included (hereinafter, a 4-step manufacturing method).

[0075] In the present invention, the reduction reaction process of the reducing agent and the polymer heat treatment process among the 1-3 step manufacturing methods can be performed at an absolute pressure of 0.01-100 atm, and preferably can be performed in a pressure range of 0.05-50 atm.

[0076] In the step 1 reduction reaction process, the gas containing carbon dioxide can be pure carbon dioxide, exhaust gas, or waste gas generated from the production process, and the carbon dioxide content contained in the gas can be 1-100 moles.

[0077] The above reducing agent reduction reaction and polymer heat treatment process can be performed at a temperature of 400°C or higher, preferably 500-700°C. A temperature of 500°C or higher is required to completely convert carbon dioxide into activated carbon, and in order to enhance electrochemical performance in the reducing agent reduction reaction, the temperature can be increased to 700°C or higher to enhance the specific surface area characteristics.

[0078] The temperature increase rate of the above reducing agent reduction reaction and polymer heat treatment process is 1 to 10 ℃min -1 It can be and preferably 2-5 ℃min -1 It could be.

[0079] In the present invention, after manufacturing the hierarchical porous carbon material in steps 1-2, the material is sequentially washed with acid, distilled water, and alcohol to remove unreacted nano-templates and unreacted polymers from step 3, and dried to obtain a porous carbon material. Specifically, hydrochloric acid, sulfuric acid, etc. can be used as the acid, and methanol, ethanol, etc. can be used as the alcohol. The washing temperature can be 0-100°C.

[0080] The step of drying the hierarchically porous carbon material washed through the above process can be performed at 40-120°C, preferably 60-90°C, under conditions of absolute pressure of 0-1 atm until all liquid evaporates.

[0081] After the temperature is raised in the above heat treatment step, the temperature can be maintained for 1 to 10 hours, preferably 2 to 3 hours.

[0082] In the present invention, any material including polyethylene oxide (PEO), polypropylene glycol, polyoxymethylene, polycarbonate, polycarprolactone, poly(p-phenylene oxide) (PPO), polyacetates, polyesters, and polyethers may be used as a polymer used when treating a polymer containing an oxygen functional group in a porous carbon material in a three-step manufacturing method.

[0083] In the present invention, it may be characterized that dispersion in the dispersion preparation step is performed using an ultrasonic processor. The dispersion time may be at least 30 minutes to ensure complete dispersion.

[0084] Nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), titanium (Ti), iron (Fe), or manganese (Mn) may be used as the transition metal in the above four-step manufacturing method, and the above compounds may be used alone or in combination of two or more. Preferably, cobalt (Co) is used, but the present invention is not limited thereto.

[0085]

[0086] According to a preferred embodiment of the present invention, a porous carbon material having micropores (< 2 nm) and mesopores (2 - 50 nm) is obtained by adding a boron-containing reducing agent to a carbon dioxide-containing gas using calcium carbonate as a nano-template and reacting the material at 500-1000°C, and then oxygen functional groups are imparted to the porous carbon material through a series of heat treatments using a polyethylene oxide polymer under an inert gas condition, and cobalt phthalocyanine, which has a stable planar structure surrounded by four nitrogen atoms to which cobalt ions can bind, is adsorbed to the carbon surface in a weakly bonded state through ultrasonic treatment, thereby manufacturing a catalyst for electrochemical production of hydrogen peroxide.

[0087] Therefore, the present invention is manufactured by the above method from another viewpoint, and the BET surface area is 400-500 m 2 / g, mesopore volume is 0.5-1.0cm 3 / g, micropore volume is 0.1-0.2cm 3 / g. The present invention relates to a porous carbon material derived from carbon dioxide doped with boron, characterized in that the oxygen ratio on the carbon surface increases according to polymer treatment.

[0088] The present invention is manufactured by a method utilizing the above nano mold from another aspect, and the BET surface area is 900-1000 m 2 / g, mesopore volume is 2.0-3.0cm 3 / g, micropore volume is 0.01-0.3cm 3 / g. It relates to a porous carbon material derived from carbon dioxide doped with boron, characterized by being.

[0089] The present invention is manufactured by the above method from another viewpoint, and I showing the degree of structural development of carbon material by Raman analysis D / I G The present invention relates to a porous carbon material derived from carbon dioxide doped with boron, characterized in that the value is 0.7 to 1 through polymer treatment and cobalt phthalocyanine adsorption. Preferably, the value of the Tafel slope may be 15-30 mV / dec in a basic electrolyte, 65-100 mV / dec in a neutral electrolyte, and 130-240 mV / dec in an acidic electrolyte.

[0090] In the present invention, the term “Tafel slope (unit: mV / dec)” refers to the change in overvoltage required when the current density in a Tafel plot increases by a factor of 10. Since the x-axis in a Tafel plot is a log scale of the current density and the y-axis corresponds to the voltage, the slope shown in the Tafel plot corresponds to mV / dec and can be obtained thereby.

[0091] The Tafel slope relates the rate of an electrochemical reaction to the overpotential and indicates the speed of electrochemical kinetics. A gentler slope indicates a more favorable reaction, indicating an efficient electron transfer process. A steeper slope indicates a slower electron transfer and reaction rate. The Tafel slope (b-factor) typically ranges from 30 to 120 mV / dec and can be used to determine whether the rate-controlling step in a process is the first or second electron transfer step, or whether a chemical reaction is involved.

[0092] The Tafel plot typically shows a linear relationship between the logarithmic value of the current and the overvoltage. Therefore, the Tafel slope is calculated as follows:

[0093] η=b×logj+a, where η, j, and b are the overvoltage, current density, and Tafel slope, respectively.

[0094] The Tafel slope is obtained from a linear fit of overvoltage versus log j, or, for linear sweep voltammetry (LSV) and impedance spectroscopy, from overvoltage versus log 1 / Rct (charge transfer resistance).

[0095] From another perspective, the present invention relates to an electrochemical method for producing hydrogen peroxide by producing H2O2 from O2 using the porous carbon material derived from carbon dioxide doped with boron.

[0096]

[0097] The BET (Brunauer-Emmett-Teller) surface area of ​​the carbon material according to the present invention is 800-1300 m 2 / g, and the pore volume is 2.5-4.0cm 3 / g, and the volume of mesopores is 1.5-3.0cm 3 / g, and I, which indicates the degree of structural development of carbon materials by Raman analysis D / I GThe value is 0.7 to 1, and the value of the Tafel slope can be 15-30 mV / dec in basic electrolytes.

[0098] The ratio of constituent elements of the surface of the carbon material according to the present invention may be carbon at ~90 at%, boron at ~10 at%, and oxygen at ~15 at%.

[0099] In addition, the onset potential for the two-electron oxygen reduction reaction of the above carbon material in a 0.1 M KOH basic solution is 0.65 to 0.90 V, and the hydrogen peroxide selectivity can be 70 to 100%.

[0100] In addition, the onset potential for the two-electron oxygen reduction reaction of the above carbon material in a 0.1 M K2SO4 neutral solution is 0.4 to 0.6 V, and the hydrogen peroxide selectivity can be 70 to 100%.

[0101] In addition, the onset potential for the two-electron oxygen reduction reaction of the above carbon material in a 0.05 M H2SO4 acidic solution is 0.3 to 0.5 V, and the hydrogen peroxide selectivity can be 40 to 80%.

[0102]

[0103] Hereinafter, embodiments of the present invention will be described in detail for reference, but are not intended to limit the scope thereof. Various modifications and variations are possible within the scope and technical spirit of the present invention, and such modifications and variations are also within the scope of the appended claims.

[0104]

[0105] [Example]

[0106] Example 1: Preparation of hierarchically porous carbon materials derived from carbon dioxide

[0107] A hierarchical porous carbon material was manufactured through a heat treatment process with carbon dioxide gas using a nano mold and a boron-containing reducing agent according to the sequence shown in Fig. 1.

[0108] 4 g of sodium borohydride (NaBH4, >99%, Sigma-Aldrich) and calcium carbonate (CaCO3, 15-40 nm, UniNanoTech Co., Ltd.) were physically mixed using a vortex mixer, placed in an alumina crucible, and then placed in a reactor (furnace). Carbon dioxide (CO2, >99.99%, Samo Co., Ltd) was then flowed at a volumetric flow rate of 80 ml / min at room temperature for 30 minutes. The temperature was then increased to 500°C at a heating rate of 5°C / min and maintained at that temperature for 2 hours. The process of converting carbon dioxide to argon inert gas (Ar, >99.9%, Samo Co., Ltd) at 600°C was included in the process of increasing the temperature again to 700°C at a heating rate of 5°C / min, and the temperature was maintained at 700°C for 2 hours. After the reactor cooled, the generated sample was washed several times with 5 molar hydrochloric acid, distilled water, and ethanol to remove unreacted nanomolds and salts.

[0109] The initial washing process involved adding 100-150 ml of distilled water to a 250 ml beaker, preparing a 5 molar concentration hydrochloric acid solution, stirring at 350 rpm at 80°C for 30 minutes, and then filtering the washed product through a 0.1 μm polycarbonate filter paper. This process was repeated a total of 3 times. The next distilled water and ethanol washing process involved stirring the filtrate with distilled water and ethanol in the same 250 ml beaker at 350 rpm for more than 1 hour, filtering the washed product through a 0.1 μm polycarbonate filter paper, and repeating the washing processes in distilled water and ethanol a total of 3 times each.

[0110] The filtrate after the above washing process was dried in an 80°C heating mantle for one day. Through the above process, a hierarchical porous carbon material was manufactured from carbon dioxide gas. The carbon material synthesized in Example 1 was named CPC (CaCO3-templated porous carbon) as shown in the drawing.

[0111]

[0112] Example 2: Preparation of a porous carbon material with oxygen functional groups introduced using a polymer

[0113] A porous carbon material with oxygen functional groups introduced was manufactured using a polymer according to the sequence shown in Figure 2-3.

[0114] 4.0 g of sodium borohydride was placed in an alumina crucible, and argon gas was flowed at a volumetric flow rate of 80 ml / min at room temperature for 30 minutes. The temperature was then increased from 25°C to 500°C at a heating rate of 5°C / min. After reaching 500°C, the argon gas was replaced with carbon dioxide gas and maintained at 500°C for 2 hours. After the reactor cooled, the generated byproducts were removed by washing several times with 5 molar hydrochloric acid, distilled water, and ethanol, and the filtrate was dried for one day. The obtained product was named BPC (Boron-doped porous carbon).

[0115] After the washing and drying process described above, polyethylene oxide (PEO, Sigma-Aldrich) and BPC synthesized by the above manufacturing method were physically mixed at a mass ratio of 4:1 using a vortex mixer, placed in an alumina crucible, and then placed in a reactor, where argon inert gas (Ar, >99.9%, Samo Co., Ltd) was flowed at a volumetric flow rate of 80 ml / min at room temperature for 30 minutes. Then, the temperature was increased to 500°C at a heating rate of 5°C / min and maintained at that temperature for 2 hours. After the reactor cooled, it was washed twice each with 5 molar concentration hydrochloric acid, distilled water, and ethanol in the same manner as the CPC washing process. The carbon material synthesized in Example 3 was named PEO-BPC as shown in the drawing.

[0116]

[0117] Example 3: Preparation of hierarchically porous carbon materials with oxygen functional groups introduced using polymers

[0118] A hierarchical porous carbon material with oxygen functional groups introduced was manufactured using a polymer according to the sequence shown in Fig. 4.

[0119] Polyethylene oxide and the CPC manufactured in Example 1 were physically mixed in a mass ratio of 4:1 using a vortex mixer, placed in an alumina crucible, and then placed in a reactor, where argon inert gas was passed through at a volume flow rate of 80 ml / min at room temperature for 30 minutes. The temperature was then increased to 500°C at a heating rate of 5°C / min and maintained at that temperature for 2 hours. After the reactor cooled, it was washed twice each with 5 molar concentration hydrochloric acid, distilled water, and ethanol in the same manner as the CPC washing process. The carbon material synthesized in Example 3 was named PEO-CPC as shown in the drawing.

[0120]

[0121] Example 4: Preparation of hierarchically porous carbon materials with cobalt single-atom catalysts

[0122] A hierarchical porous carbon material with oxygen functional groups introduced by dispersing and adsorbing a cobalt single-atom catalyst was manufactured according to the sequence shown in Fig. 5.

[0123] 30 mg of PEO-CPC manufactured in Example 3 and 30 mg of dimethylformamide solvent were placed in a 70 ml vial and sonicated for 1 hour. Then, a 2.5 wt% cobalt phthalocyanine sample was added to the vial and sonicated for 30 minutes. Centrifugation was performed at 8000 rpm for 20 minutes using a centrifuge, and the obtained precipitate was washed several times with dimethylformamide solvent and ethanol.

[0124] The initial washing process involved adding 100-150 ml of distilled water to a 250 ml beaker, preparing a 5 molar hydrochloric acid solution, stirring at 350 rpm at room temperature for more than 30 minutes, and then filtering the washed product through a 0.02 μm polytetrafluoroethylene (poly(1,1,2,2-tetrafluoroethylene)) filter paper. This process was repeated three times in total. The next ethanol washing process involved stirring the filtrate and ethanol in the same 250 ml beaker at 350 rpm for more than 1 hour, and then filtering the washed product through a 0.1 μm polycarbonate filter paper, a process repeated three times in total.

[0125] The filtrate after the above washing process was freeze-dried. The hierarchical porous carbon material with the cobalt single-atom catalyst introduced through the above process was named CoPc-PEO-CPC (CoPc: Cobalt Phthalocyanine) as shown in the drawing.

[0126]

[0127] Example 5: Preparation of porous carbon materials using polymers without oxygen functional groups

[0128] A porous carbon material was manufactured using a polymer without oxygen functional groups according to the sequence shown in Fig. 6.

[0129] Polyethylene (Sigma-Aldrich) and BPC synthesized by the manufacturing method presented in Example 2 were physically mixed at a mass ratio of 4:1 using a vortex mixer, placed in an alumina crucible, and then placed in a reactor, where argon inert gas (Ar, >99.9%, Samo Co., Ltd) was flowed at a volume flow rate of 80 ml / min at room temperature for 30 minutes. Then, the temperature was increased to 500°C at a heating rate of 5°C / min and maintained at that temperature for 2 hours. After the reactor cooled, it was washed twice each with 5 molar concentration hydrochloric acid, distilled water, and ethanol in the same manner as the washing process described above. The carbon material synthesized in Example 3 was named PE-BPC as shown in the drawing.

[0130]

[0131] Experimental Example 1: Comparison of the Morphological Structures of Hierarchically Porous Carbon Materials

[0132] To compare the morphological structures of the carbon materials manufactured through Examples 1-5, SEM analysis was performed and shown in Figures 7-8. The porosity of the materials is inherent in the pure materials of CPC and BPC manufactured in Examples 1 and 2. The pore structural characteristics of the carbon materials are formed through interaction with carbon dioxide. Furthermore, it was confirmed that high-temperature treatment and thermal decomposition of the polymer did not significantly affect the carbon structure.

[0133]

[0134] Experimental Example 2: Confirmation of Cobalt Single-Atom Catalyst Adsorption in Hierarchically Porous Carbon Materials

[0135] In order to confirm the adsorption of the cobalt single-atom catalyst on the carbon material manufactured through the above Example 4, STEM dark field mode analysis and TEM EDS analysis were performed, and the results are shown in Figs. 9 and 10, respectively. It was confirmed that a small amount of cobalt was effectively adsorbed in a single-atom form through ultrasonic treatment.

[0136]

[0137] Experimental Example 3: Comparison of the Crystal Structures of Hierarchically Porous Carbon Materials

[0138] XRD analysis was performed to compare the crystal structures of the carbon materials manufactured through Examples 1-5, and the results are presented in Fig. 11. It was confirmed that the amorphous nature of the materials was inherent in the pure materials of CPC and BPC manufactured in Examples 1 and 2, and that high-temperature treatment and thermal decomposition of the polymer did not significantly affect the crystal structure of the carbon.

[0139]

[0140] Experimental Example 4: Comparison of adsorption isotherms, BET surface areas, and pore volume distributions of hierarchically porous carbon materials.

[0141] The N2 adsorption-desorption isotherms, BET surface areas, mesopore distributions according to the Barrett-Joyner-Halenda (BJH) desorption method, and t-plot micropore distributions of the carbon materials manufactured through Examples 1-5 are shown in FIGS. 12-14, respectively. As a result, the BET surface areas of the carbon materials manufactured through Examples 1-5 were confirmed to be 1293.93 m² / g (Example 1), 463.03 m² / g (Example 2), 1035.34 m² / g (Example 3), 942.88 m² / g (Example 4), and 487.42 m² / g (Example 5), respectively, and the detailed values ​​are presented in Table 1. Due to the effect of the nano-template, the surface areas of Examples 1, 3, and 4 showed significantly larger values ​​than that of Example 2. As a result of pore distribution analysis using the BJH method, the mesopore volumes of the carbon materials manufactured in Examples 1-4 were 2.699 cm³ / g, 0.635 cm³ / g, 2.922 cm³ / g, 2.672 cm³ / g, and 0.785 cm³ / g, respectively, and the micropore volumes were confirmed to be 0.15 cm³ / g, 0.13 cm³ / g, 0.055 cm³ / g, 0.038 cm³ / g, and 0.121 cm³ / g, respectively. As with the BET surface area analysis results, the carbon material of Example 2 had less mesopore formation than Examples 1, 3, and 4 due to the effect of the nano-template. In addition, the reason why the BET surface area slightly decreased when the polymer was treated can be interpreted as a decrease in the micropore volume due to the collapse of the existing carbon structure and destruction of pores caused by the thermal decomposition of the polymer on the carbon surface.

[0142]

[0143] Experimental Example 5: Comparison of the Surface Element Ratios and the Differences in the Boron-Carbon and Oxygen-Carbon Arrangement Structures of Hierarchically Porous Carbon Materials

[0144] The amount of elements contained in the hierarchical porous carbon materials manufactured by Examples 1-5 was analyzed by X-ray photoelectron spectroscopy (XPS), and the results are presented in Figs. 15-17. The exact atomic percentages (at%) of the porous carbon materials obtained in Examples 1-5 are presented in detail in Table 2. The hierarchical porous carbon materials manufactured using CaCO₃ as a nano-template in Examples 1 and 3-4 had relatively low boron contents, and it was confirmed that the at% of oxygen increased through the polyethylene oxide polymer treatment. In particular, when comparing the PEO-BPC manufactured in Example 2 with the PE-BPC manufactured in Example 5, a distinct difference in the oxygen atomic percentage was confirmed depending on whether the polymer contained an oxygen functional group. In Fig. 16, the boron-carbon arrangement structure of the porous carbon obtained by Example 2 was analyzed through deconvolution of the XPS B1s peak. Figure 17 shows the results of analyzing the oxygen-carbon arrangement structure of the hierarchical porous carbon obtained by Example 1 and Examples 3-4 through deconvolution of the XPS O1s peak.

[0145]

[0146] Experimental Example 6: Comparison of Defect Distributions in Hierarchically Porous Carbon Materials

[0147] Raman analysis was performed to investigate the defect distribution of the hierarchical porous carbon materials manufactured by the above Examples 1, 3 and 4, and the analysis results are shown in Fig. 18. I indicating the degree of structural development of the carbon material by Raman analysis D / I GThe values ​​are 0.7757 (Example 1), 0.8827 (Example 3), and 0.9647 (Example 4), respectively, and it can be confirmed that the hierarchical porous carbon material including cobalt single atoms manufactured in Example 4 has the highest degree of defects.

[0148]

[0149] Experimental Example 7: Comparison of Current-Potential Curves by Linear Cyclic Voltammetry (LSV) of Hierarchically Porous Carbon Materials

[0150] The current-potential curves of the porous carbon materials manufactured by the above Examples 1-5 by linear cyclic voltammetry (LSV) are shown in Figs. 19-21. Linear cyclic voltammetry is a method of obtaining current data according to the voltage while measuring at a constant voltage change rate. In this study, a catalyst was placed on a glassy carbon electrode, and the rotation speed of the electrode was set to 1600 rpm. In the case of the two-electron oxygen reduction reaction, the higher the current density value, the higher the catalytic activity, and the selectivity for hydrogen peroxide is expressed as the ratio between the two-electron reaction and the four-electron reaction, which can be measured as the ratio of the disk current and the ring current values, and this is expressed by the following equation. (N is the collection efficiency)

[0151] H2O2Selectivity = 200*(I r / N) / (I d +(I r / N)), N = 0.25

[0152]

[0153] In Fig. 19, it can be seen that the catalysts synthesized in Examples 1 and 3-4 under basic conditions have a larger surface area than the catalyst synthesized in Example 2, resulting in a significant increase in current, and that the catalytic activity and hydrogen peroxide selectivity are improved when polymer treatment is performed. In addition, it can be confirmed that the catalytic active site is increased through cobalt phthalocyanine adsorption in Example 4, resulting in an improvement in current and hydrogen peroxide selectivity.

[0154] At 0.65 V vs. RHE voltage, the selectivities of the catalysts synthesized in Examples 1-5 were high, 76.8% (Example 1), 89.3% (Example 2), 85.2% (Example 3), 90.0% (Example 4), and 85.7% (Example 5), respectively. In particular, when comparing Examples 1 and 3, and also comparing the BPC material (82.1% (0.65 V vs. RHE)) with the material of Example 2, it can be confirmed that the polymer treatment provides a higher hydrogen peroxide selectivity. This shows that oxygen acts as an active site of the catalyst.

[0155] The effect of enhancing the catalyst through the polymer can also be confirmed in Fig. 20. Under neutral conditions, the selectivity was very high at 78.5% (Example 1), 96.5% (Example 3), and 99.7% (Example 4) at 0.65 V vs. RHE voltage, respectively, and the current was also enhanced by the two-electron oxygen reduction reaction.

[0156] In Fig. 21, the selectivity was 47.6% (Example 1), 57.6% (Example 3), and 75.8% (Example 4) at 0.1 V vs. RHE voltage under acidic conditions, respectively. This is the result of improved selectivity due to the effect of polymer treatment and cobalt phthalocyanine catalyst, similar to the above results.

[0157]

[0158] Experimental Example 8: Comparison of the Oxygen Reduction Reaction Kinetics of Hierarchically Porous Carbon Materials

[0159] In order to compare the oxygen reduction reaction kinetics of the porous carbon materials manufactured by the above Examples 1 and 3-4, the Tafel slopes were compared. The Tafel slope values ​​were 34.21 mv / dec (Example 1), 21.03 mv / dec (Example 3), and 17 mv / dec (Example 4) under alkaline conditions, 94.27 mv / dec (Example 1), 82.41 mv / dec (Example 3), and 66.88 mv / dec (Example 4) under neutral conditions, and 230.56 mv / dec (Example 1), 158.25 mv / dec (Example 3), and 134.11 mv / dec (Example 4) under acidic conditions. A smaller Tafel slope indicates a faster oxygen reduction reaction rate, indicating a more suitable catalyst for oxygen reduction. It was confirmed that the Tafel slope decreased as oxygen functional groups were formed through polymer treatment and as cobalt atoms were adsorbed.

[0160]

[0161] Experimental Example 9: Comparison of Current-Potential Curves Using an H-Type Cell Using Porous Carbon Materials

[0162] In order to evaluate the oxygen reduction reaction in the bulk electrolyte of the porous carbon material manufactured by Example 2 in Fig. 22, an H-type cell consisting of two chambers was constructed. 100 mg cm was prepared through the drop method. -2 The electrode was constructed by coating the catalyst on both sides in an amount of . Graphite was constructed as a counter electrode, Ag / AgCl as a reference electrode, and Nafion 117 was used as a separator. 40 ml of 0.1 M KOH solution was used as an electrolyte, and the IV curve of the porous carbon material manufactured in Example 2 in Fig. 23 was performed using chronoamperometry. It was continuously and stably maintained within the range of 2-3.5 mA at 0.4 V vs. RHE, indicating continuous hydrogen peroxide production through ORR.

[0163]

[0164] Experimental Example 10: Quantitative analysis of hydrogen peroxide electrochemically generated by an H-type cell using porous carbon materials and calculation of the faradaic efficiency (FE).

[0165] A relatively low overpotential of 0.4 V was applied to synthesize hydrogen peroxide, and the concentration of the generated hydrogen peroxide was quantitatively analyzed using the Ce(SO4)2 titration method. Hydrogen peroxide generated by the following formula reacted with Ce(SO4)2 in a 0.5 M H2SO4 solution, and was measured by UV-spectroscopy, and the amount of hydrogen peroxide was titrated. The results of the absorbance according to the amount of added hydrogen peroxide using the absorbance at 320 nm are shown in Figure 24.

[0166] H2O2+ 2Ce(SO4)2→ Ce2(SO4)3+ H2SO4+ O2

[0167]

[0168] As a result of using the porous carbon material produced by Example 2 as a hydrogen peroxide production catalyst, 4.78 mM of hydrogen peroxide was produced over 4 hours, and the Faraday efficiency (FE) reached approximately 90%, as shown in Fig. 25. The Faraday efficiency of hydrogen peroxide synthesis was maintained at ~90% for 4 hours, and high hydrogen peroxide production could be continuously maintained in the bulk system. The average hydrogen peroxide production rate measured based on the amount of hydrogen peroxide produced over 4 hours was 452.96 mmol g cat -1 h -1As can be seen in Fig. 26, the initial current was maintained during the 18-hour hydrogen peroxide generation test, and the faradaic efficiency also maintained a high efficiency of 92%. The average hydrogen peroxide generation rate measured based on the amount of hydrogen peroxide generated for 18 hours was 393.5 mmol g cat -1 h -1 was. (Fig. 26)

[0169]

[0170] Experimental Example 11: Quantitative Analysis of Electrochemically Generated Hydrogen Peroxide by an H-Type Cell Using Hierarchically Porous Carbon Materials

[0171] As a result of using the porous carbon material manufactured in Example 4 as a hydrogen peroxide production catalyst under chronoamperometry conditions of 0.3 V vs. RHE in a central electrolyte in Fig. 27, 619.95 mmol g for 12 hours cat -1 h -1 The average hydrogen peroxide production rate was shown.

[0172]

[0173] While specific aspects of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific descriptions merely represent preferred embodiments and are not intended to limit the scope of the present invention. Therefore, the substantial scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for producing a porous carbon material derived from boron-doped carbon dioxide, comprising the following steps: (a) a step of reacting a reducing agent containing boron with a gas containing carbon dioxide to obtain a porous solid product; and (b) A step of obtaining a porous carbon material into which oxygen functional groups are introduced by heat-treating a polymer including oxygen functional groups.

2. A method for producing a porous carbon material derived from carbon dioxide doped with boron, further comprising a step of adding a nano mold to a reducing agent prior to step (a) in the first paragraph.

3. A method for producing a porous carbon material derived from carbon dioxide doped with boron, characterized in that in paragraph 1, the polymer including an oxygen functional group is at least one selected from the group consisting of polyethylene oxide, polypropylene glycol, polyoxymethylene, polycarbonate, polycarprolactone, poly(p-phenylene oxide) (PPO), polyacetates, polyesters, and polyethers.

4. A method for producing a porous carbon material derived from carbon dioxide doped with boron, further comprising a step of dispersing or adsorbing metal phthalocyanine molecules after step (b) in the first paragraph.

5. A method for producing a porous carbon material derived from carbon dioxide doped with boron, characterized in that in the fourth paragraph, the metal of the metal phthalocyanine molecule is at least one selected from the group consisting of nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), titanium (Ti), iron (Fe), and manganese (Mn).

6. A method for producing a porous carbon material derived from carbon dioxide doped with boron, characterized in that in paragraph 1, the reducing agent containing boron is selected from the group consisting of boron oxide (B2O3), boric acid (H3BO3), lithium boron hydride (LiBH4), sodium boron hydride (NaBH4), potassium boron hydride (KBH4), magnesium boron hydride (Mg(BH4)2), calcium boron hydride (Ca(BH4)2), strontium boron hydride (Sr(BH4)2), sodium detraborate (Na2B4O5(OH)48H2O), and barium tetraborate (BaB2O4).

7. A method for producing a porous carbon material derived from carbon dioxide doped with boron, further comprising a step of washing and drying the porous carbon material after step (b) in the first paragraph.

8. A method for producing a porous carbon material derived from carbon dioxide doped with boron, characterized in that in the second paragraph, the nano mold is at least one selected from the group consisting of transition metals, alkali metals, alkaline earth metals, noble metals, oxides of the metals, carbonates of the metals, and chlorides of the metals.

9. A method for producing a porous carbon material derived from carbon dioxide doped with boron, characterized in that in paragraph 8, the transition metal is nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn), titanium (Ti), iron (Fe), or manganese (Mn), the alkali metal is lithium (Li), sodium (Na), or cesium (Cs), the alkaline earth metal is magnesium (Mg), calcium (Ca), or strontium (Sr), and the precious metal is gold (Au), platinum (Pt), or silver (Ag).

10. In the second paragraph, the nano mold is CaO, MgO, Fe2O3, Fe3O4, CaCO 3, Na2CO 3, A method for producing a porous carbon material derived from carbon dioxide doped with boron, characterized in that at least one material is selected from the group consisting of NiCO3, CoCO3, Li2CO3, and FeCO3.

11. Manufactured by the method of paragraph 1, and having a BET surface area of ​​400-500 m 2 / g, mesopore volume is 0.5-1.0cm 3 / g, micropore volume is 0.1-0.2cm 3 A porous carbon material derived from carbon dioxide doped with boron, characterized by having / g.

12. Manufactured by the method of paragraph 2, and has a BET surface area of ​​900-1000 m 2 / g, mesopore volume is 2.0-3.0cm 3 / g, micropore volume is 0.01-0.3cm 3 A porous carbon material derived from carbon dioxide doped with boron, characterized by having / g.

13. Manufactured by the method of Article 4, 0.05 to 10 parts by weight of metal phthalocyanine is adsorbed per 100 parts by weight of carbon material, and I indicating the degree of structural development of the carbon material by Raman analysis D / I G A porous carbon material derived from carbon dioxide doped with boron, characterized by a value of 0.7 to 1.

14. A porous carbon material derived from carbon dioxide doped with boron, characterized in that the value of the Tafel slope in the 13th paragraph is 15-30 mV / dec in a basic electrolyte, 65-100 mV / dec in a neutral electrolyte, and 130-240 mV / dec in an acidic electrolyte.

15. An electrochemical method for producing hydrogen peroxide by producing H2O2 from O2 using a porous carbon material derived from carbon dioxide doped with boron according to any one of claims 11 to 14.

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