JP2012250884A - Porous carbon nitride film, method of manufacturing the same, and application using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bimodal porous carbon nitride film having macropores and mesopores, a method of manufacturing the same, and applications using the same.SOLUTION: A porous carbon nitride film is formed by a frame structure composed of carbon nitride. The frame structure has macropores and mesopores having a smaller pore diameter than the macropores. The macropores are regularly arranged in the surface direction of the porous carbon nitride film. The macropores have openings in the surface of the porous carbon nitride film.

Description

  The present invention relates to a carbon nitride film, a manufacturing method thereof, and an application using the carbon nitride film, and more particularly to a bimodal porous carbon nitride film, a manufacturing method thereof, and an application using the same.

  Carbon nitride material has hardness, toughness, low friction coefficient, chemical inertness, stable field emission, wide band gap, biocompatibility, negative electron affinity, high thermal conductivity, acid resistance, water resistance comparable to diamond It is expected to be applied to biocompatible coating materials for biological implants, fuel cell electrodes, gas separation, corrosion prevention, catalysts, lubrication, molecular adsorption and gas sensors.

  The inventors have succeeded in producing a carbon nitride porous body using various templates (for example, Patent Documents 1 to 3). According to Patent Documents 1 and 2, a technique for producing a carbon nitride porous body using SBA-15 as a template is disclosed. Patent Document 3 discloses a technique for producing a carbon nitride porous body using SBA-16 as a template.

  However, all such carbon nitride porous bodies are mesoporous materials having a single pore diameter (50 nm or less), and are preferable for suppressing the diffusion of large molecules.

  Therefore, in order to expand applications, it is desired to develop a hierarchically ordered porous carbon nitride material, that is, a porous carbon nitride material having macropores and mesopores.

  As described above, an object of the present invention is to provide a bimodal porous carbon nitride film having macropores and mesopores, a method for producing the same, and an application using the same.

The porous carbon nitride film according to the present invention is formed by a frame structure made of carbon nitride, and the frame structure has macropores and mesopores having a pore diameter smaller than the pore diameter of the macropores. The macropores are regularly arranged in the surface direction of the porous carbon nitride film, and the macropores have openings on the surface of the porous carbon nitride film, thereby Achieve the challenge.
The pore diameter of the macropores may be in the range of 50 nm to 15 μm.
The mesopores may have a pore diameter ranging from 5 nm to 20 nm.
The carbon nitride contains a metal element and / or a lanthanoid element selected from the group consisting of Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt and Au. Also good.
The carbon nitride may be amorphous carbon nitride.
The N / (C + N) ratio (atomic%) due to nitrogen atoms N and carbon atoms C in the carbon nitride may be in the range of 10% to 25%.
The method for producing a porous carbon nitride film according to the present invention includes a step of applying a first solution containing a silica source and a block copolymer to a macroporous template comprising particles, and the first solution is applied. The macropore template is heated to produce silica from the silica source, and has the macropore template and the mesopore template comprising the block copolymer and the silica. Forming, applying a second solution containing a carbon nitride precursor to the macro mesopore template, and heating the macro mesopore template provided with the second solution. Polymerizing the carbon nitride precursor, and the macro mesopore template having the polymerized carbon nitride precursor. Heating the polymer, carbonizing the polymerized carbon nitride precursor, and removing the particles and the block copolymer from the macro-mesopore template; and the particles and the block copolymer Is removed, and the carbonized carbon nitride precursor and the silica product are treated with an acid or an alkali to remove the silica, thereby achieving the above object.
The silica source may be tetraethoxysilane (TEOS) or sodium silicate.
The block copolymer may be selected from the group consisting of P104, P123, F108 and F127.
The carbon nitride precursor may be selected from the group consisting of polyethyleneimine, aniline, melamine and ethylenediamine.
The second solution contains metal ions and / or lanthanoid ions selected from the group consisting of Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt, and Au. May be.
The particle size may be in the range of 50 nm to 15 μm.
In the step of generating the silica, the macropore template to which the first solution is applied may be heated in a temperature range of 80 ° C. to 150 ° C. for 12 hours to 36 hours.
The step of polymerizing the carbon nitride precursor comprises subjecting the macro mesopore template provided with the second solution to a first temperature range of 50 ° C. to 100 ° C. for 2 hours to 6 hours, You may heat for 2 hours-6 hours in the temperature range of 160 to 200 degreeC higher than a 1st temperature range.
The carbonizing and removing step includes heating the macro mesopore template having the polymerized carbon nitride precursor in a temperature range of 400 ° C. to 600 ° C. for 2 hours to 6 hours in an inert atmosphere. Also good.
In the acid or alkali treatment, hydrofluoric acid or sodium hydroxide may be used.
The macropore template may be a colloidal crystal.
Following the step of removing the silica, a step of ozone treatment of the porous carbon nitride film may be further included.
The sensor according to the present invention includes the porous carbon nitride film, thereby achieving the above object.
The filter according to the present invention includes the porous carbon nitride film, thereby achieving the above object.

  The porous carbon nitride film of the present invention is formed by a frame structure made of carbon nitride. The frame structure has macropores and mesopores having a pore size smaller than the pore size of the macropores. That is, since the porous carbon nitride film of the present invention is a bimodal porous carbon nitride film having macropores and mesopores, it has a large surface area and adsorbs or permeates substances having different sizes. Therefore, the application can be expanded. Furthermore, the macropores are arranged in the surface direction of the porous carbon nitride film, have openings in the cross-sectional direction of the porous carbon nitride film, and are extremely regular. Therefore, quantitative determination of mass transport is possible, which is advantageous. Further, since the porous carbon nitride film of the present invention is in the form of a film, the film thickness can be easily controlled by changing from a single layer to multiple layers. Since the porous carbon nitride film of the present invention has a selective adsorption ability for a catalyst, an adsorbent, a filter, and a predetermined substance, the above-described porous carbon nitride film is similar to the above-mentioned sensor or optical switch or the existing porous material. In addition to applications, it can be used for gas separation, chromatography, energy storage.

  A method for producing a porous carbon nitride film according to the present invention comprises a step of applying a first solution containing a silica source and a block copolymer to a macroporous template comprising particles, and heating the first solution. Generating silica from a silica source to form a macro mesopore template, applying a second solution containing a carbon nitride precursor to the macro mesopore template, and Heating to polymerize the carbon nitride precursor, heating the polymerized carbon nitride precursor and macro-mesopore template, carbonizing the carbon nitride precursor, and removing the block copolymer and particles; And an acid or alkali treatment of the product to remove the silica.

  According to the method of the present invention, since the block copolymer coated with particles and silica is used as a template, the pore diameters of the macropores and the mesopores in the obtained porous carbon nitride film are the same as those of the particles and blocks, respectively. Reflects the size of the copolymer. Therefore, the pore diameters of the macropores and mesopores can be easily controlled by appropriately selecting the sizes of the particles and the block copolymer. Moreover, since the arrangement of macropores in the porous carbon nitride film reflects the arrangement of particles in the template, regular arrangement of macropores can be easily achieved.

  According to the method of the present invention, macropores and mesopores are formed by applying the first solution described above to a macropore template, and forming silica to form a macro mesopore template. A macro mesopore template with a structure that can be produced is produced. Since such a macro mesopore template is used, the porosity is controlled in a bimodal manner and the pore size of macropores and mesopores and / or the arrangement of macropores without complicated control. A carbon nitride film can be easily obtained.

Schematic showing a porous carbon nitride film according to the present invention. The flowchart which shows the process of manufacturing the porous carbon nitride film of this invention Schematic diagram showing the production of the porous carbon nitride film of the present invention Schematic showing a filter using the porous carbon nitride film of the present invention The figure which shows the SEM image of the thin film ₁₄₅₀ by Example 1. The figure which shows the TEM image of the thin film ₁₄₅₀ by Example 1. FIG. The figure which shows the SEM image of the thin films 2 and 3 by Example 2 and 3 The figure which shows the XRD pattern of the thin film ₁₄₅₀ by Example 1 The figure which shows the EELS mapping image of the thin film ₁₄₅₀ by Example 1 The figure which shows the XPS spectrum of the thin film ₁₄₅₀ by Example 1 The figure which shows the FTIR spectrum of the thin film ₁₄₅₀ by Example 1. The figure which shows the heating temperature dependence of N / (C + N) ratio of the thin film 1 by Example 1. The figure which shows the time dependence of the QCM frequency shift amount with respect to aniline and acetic acid of the thin film ₁₄₅₀ by Example 1. The figure which shows the QCM frequency shift amount with respect to the aniline and acetic acid of the thin film ₁₄₅₀ before and behind ozone treatment by Example 1 (treatment time 15 minutes).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same number is attached | subjected to the same element and the description is abbreviate | omitted.

(Embodiment 1)
In Embodiment 1, the structure of the porous carbon nitride film according to the present invention will be described in detail.

  FIG. 1 is a schematic view showing a porous carbon nitride film according to the present invention.

  FIG. 1 (A) is a view showing the surface of a single layer porous carbon nitride film according to the present invention, and FIG. 1 (B) is a view showing an A-B cross section in FIG. 1 (A). .

  The porous carbon nitride film 100 of the present invention is formed by a frame structure 110 made of carbon nitride. Since the carbon nitride constituting the frame structure 110 is amorphous carbon nitride, the porous carbon nitride film 100 according to the present invention is excellent in mechanical and chemical stability. Further, the N / (C + N) ratio (atomic%) of the nitrogen atom (N) to the nitrogen atom (N) and carbon atom (C) in the carbon nitride is in the range of 10% to 25%.

  The carbon nitride further contains a metal element and / or a lanthanoid element selected from the group consisting of Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt and Au. Also good. Since these metal elements and lanthanoid elements have a catalytic action, catalytic activity can be imparted to the porous carbon nitride film 100 of the present invention.

  The frame structure 110 has macro pores 120 and mesopores 130.

  The macro pores 120 are regularly arranged in the surface direction of the porous carbon nitride film 100. In this specification, the “surface direction” of the film means a direction parallel to the surface of the film. The regular arrangement depends on the arrangement of particles, which will be described later, and is, for example, close-packed, colloidal, photonic, or the like. Furthermore, the macropore 120 has an opening 140 on the outermost surface of the porous carbon nitride film 100 as shown in FIG. As shown in FIG. 1B, the cross section of the macropores 120 in the thickness direction (direction perpendicular to the surface direction) is hemispherical.

  In FIG. 1 (A), the macropores 120 are shown as being hollow, but the white portions are part of the frame structure 110 and, as shown in FIG. 1 (B), are hemispherical. Note that it is a sidewall. However, in the manufacturing process described later, when the degree of adhesion between the macropore template (310) and the substrate (320) or a multilayer macropore template is used, a part of the side wall (for example, the bottom portion) ) May penetrate.

  The pore diameter R of the macropore 120 depends on the particle diameter of the particles described later, but is in the range of 50 nm to 15 μm from the range of selectable particles.

  The mesopores 130 have a pore diameter smaller than that of the macropores 120 and are scattered in portions other than the macropores 120 in the frame structure 110. In FIG. 1, the mesopores 130 are shown only partially in order to avoid complicating the figure, but it should be noted that in practice they are scattered throughout the frame structure 110.

  The mesopores 130 are pores generated as replicas of a block copolymer, which will be described later, and the pore diameter is in the range of 5 nm to 20 nm in consideration of the size of the block copolymer that can be selected. In addition, since the mesopores 130 are replicas of the block copolymer, the shape of the mesopores 130 can also be controlled by selecting the block copolymer.

  The film thickness d of the porous carbon nitride film 100 of the present invention depends on the particle size of the particles described later, and can be substantially the same as the selected particle size or slightly smaller than the particle size. Accordingly, when it is desired to increase the film thickness d of the single-layer porous carbon nitride film 100 of the present invention, particles having a large particle diameter may be employed during manufacturing.

  Thus, since the porous carbon nitride film 100 of the present invention is a bimodal porous carbon nitride film having the macropores 120 and the mesopores 130, it has a large surface area, and is used as a catalyst and an adsorbent. Can be used. The porous carbon nitride film 100 of the present invention is suitable as an adsorbent for extremely large substances because the pore diameter of the macropores 120 is in the range of 50 nm to 15 μm.

  Since the porous carbon nitride film 100 of the present invention is bimodal, it adsorbs or permeates substances having different sizes. For example, it is possible to exhibit a multi-functionality such that a large substance is adsorbed on the macropores 120, a small substance is adsorbed on the mesopores 130, and other substances are permeated. If such a function is used, the porous carbon nitride film 100 of the present invention can be used as a filter for filtering various substances and a sensor for sensing various substances.

  The macro pores 120 are arranged in the direction of the surface of the porous carbon carbonitride film 100, have openings 140 on the outermost surface of the porous carbon nitride film 100, and are extremely regular. Therefore, the porous carbon nitride film 100 of the present invention enables quantitative determination of material transport.

  Although the porous carbon nitride film 100 which is a single layer of the present invention has been described with reference to FIG. 1, the porous carbon nitride film of the present invention is not limited to this. The single-layer porous carbon nitride film 100 shown in FIG. 1 may be a multilayer. By making it multilayer, it can be a porous carbon nitride film having a film thickness according to the application.

(Embodiment 2)
In the second embodiment, a method for producing a porous carbon nitride film of the present invention will be described. The present inventors succeeded in producing the porous carbon nitride film described in detail in Embodiment 1 by employing particles as a macropore template and a block copolymer as a mesopore template.

FIG. 2 is a flowchart showing a process for producing the porous carbon nitride film of the present invention.
FIG. 3 is a schematic view showing how the porous carbon nitride film of the present invention is manufactured.

  The manufacturing method of the present invention uses a macropore template 310 composed of particles 300. In FIG. 3, the macropore template 310 composed of particles 300 is located on the substrate 320. If it exists on the board | substrate 320, handling will become easy. The substrate 320 is an arbitrary substrate on which the macropore template 310 can be disposed and can be exposed to a temperature of about 600 ° C., and is, for example, a Si substrate, a glass substrate, or a quartz substrate.

  The particles 300 are polystyrene or polymethyl methacrylate (PMMA). Since these particles do not easily react with the silica source and the carbon nitride precursor in the subsequent steps, a high-purity porous carbon nitride film can be obtained. Since these particles are a polymer material, they can be completely eliminated by firing at a predetermined temperature. These particles are commercially available, and it is easy to obtain particles having an arbitrary particle size. The particle size of the particles is in the range of 50 nm to 15 μm. The particle size selected here is the pore size R of the macropore 120 (FIG. 1) in the porous carbon nitride film 100 (FIG. 1) of the present invention. A porous carbon nitride film having a desired pore diameter can be obtained simply by selecting.

  In particular, in the case of the macroporous template 310 in which only one layer of the particles 300 is arranged as shown in FIG. The range in which the solution penetrates into the macropore template 310) can be the film thickness d of the porous carbon nitride film 100. Therefore, when the porous carbon nitride film 100 having a large film thickness is obtained, the macropore template 310 made of particles having a large particle diameter is selected, and when the porous carbon nitride film 100 having a thin film thickness is obtained. The macropore template 310 made of particles having a small particle size may be selected.

  The arrangement of the particles 300 of the macropore template 310 is the arrangement of the macropores 120 (FIG. 1) in the porous carbon nitride film 100. Therefore, in order to obtain the porous carbon nitride film 100 having the macropores 120 periodically and regularly arranged, the macropore template 310 is close-packed, colloidal, or photonic crystal-like. . In particular, a close-packed colloidal crystal composed of colloidal particles can be regularly arranged to obtain a porous carbon nitride film having a high specific surface area and a large pore volume. Note that the macropore template 310 described above can be easily realized by referring to colloidal crystal manufacturing technology using colloidal particles.

  Step S <b> 210: A first solution containing the silica source 330 and the block copolymer 340 is applied to the macropore template 310 including the particles 300.

  The silica source 330 may be any material that can be converted to silica by heating, but is preferably tetraethoxysilane (TEOS) or sodium silicate. All of these are readily available or synthesized and are known to become silica upon heating.

  Since the block copolymer 340 can serve as a template for the mesopores 130 (FIG. 1), any block copolymer having the desired pore size and shape of the mesopores 130 is adopted, but preferably P104 , P123, F108 and F127. These block copolymers have a track record in forming mesopores and are easily available.

  The first solution is preferably a mixed solution of the block copolymer 340 and water. This mixed solution is stirred at room temperature for several hours (eg, 4 hours), then a silica source 330 is added and stirred at a temperature range of 35 ° C. to 45 ° C. for 10 minutes to 20 minutes. Thus, the block copolymer 340 and the silica source 330 are sufficiently mixed, so that the inside of the block copolymer 340 can be filled with the silica source 330 and covered with the silica source 330 in a capsule shape. The first solution preferably contains an acid. The acid is an arbitrary acid that functions as a catalyst in the reaction of Step S220 described later and promotes the formation of silica, and specifically, hydrochloric acid, sulfuric acid, nitric acid, and the like.

  The application of the first solution to the macropore template 310 is performed by dropping the first solution, immersing the macropore template 310 in the first solution, or the like.

  Prior to application of the solution in step S210 to the macropore template 310, the macropore template 310 and the substrate 320 may be heated. Such heating is performed at 100 ° C. for 10 minutes, for example. Thereby, since the adhesiveness of the macropore template 310 and the board | substrate 320 improves, it can prevent the macropore template 310 falling off from the board | substrate 320 in the middle of manufacture.

  Step S220: The macropore template 310 to which the first solution is applied is heated to generate silica from the silica source 330. The heating is performed for 12 hours to 36 hours in the air at a temperature range of 80 ° C. to 150 ° C. with the macropore template provided with the first solution. As a result, the silica source 330 becomes completely silica, and the block copolymer 340 becomes a silica-block copolymer encapsulated with silica that serves as a template for mesopores. This silica-block copolymer functions as the mesopore template 350.

  Through the above steps S210 and S220, a macro mesopore template 360 for forming macropores and mesopores in the porous carbon nitride film of the present invention is obtained. That is, a macro-meso fine having a macro-pore template 310 composed of particles 300 and a meso-pore template 350 composed of silica and a block copolymer (specifically, a silica-block copolymer covered with silica). A hole template 360 is obtained.

  Step S230: The second solution 370 containing the carbon nitride precursor is applied to the macro mesopore template 360 obtained in Step S220.

  The carbon nitride precursor may be any precursor that becomes carbon nitride upon heating, but is preferably selected from the group consisting of polyethyleneimine, aniline, melamine, and methylenediamine. All of these are easy to obtain or synthesize, are inexpensive, and are surely converted to carbon nitride by steps S240 and S250 described later.

  The second solution 370 contains metal ions and / or lanthanoid ions selected from the group consisting of Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt, and Au. May be. By containing these ions, carbon nitride to which these ions are added can be obtained, and catalytic activity due to these ions can be expected.

  Also here, the application of the second solution 370 to the macro mesopore template 360 is performed in the same manner as in step S210. The dropping of the second solution and the addition of the macro mesopore template 360 into the second solution 370 are performed. It is performed by dipping or the like.

  Step S240: The macro mesopore template 360 provided with the second solution 370 is heated to polymerize the carbon nitride precursor. By heating, the carbon nitride precursor reacts and is polymerized (polymerized carbon nitride precursor 380). Specifically, the polymerization is performed by heating the macro mesopore template 360 provided with the second solution 370 in a first temperature range that is relatively low temperature, and then higher than the first temperature range. It is performed by heating in the second temperature range. By carrying out in two steps, the carbon nitride precursor is heated rapidly and is prevented from vaporizing, and can be polymerized efficiently.

  More preferably, the polymerization is carried out by subjecting the macro mesopore template 360 provided with the second solution 370 to a first temperature range of 50 ° C. to 100 ° C. for 2 hours to 6 hours, and then to a first temperature range. It is carried out by heating at a higher temperature range of 160 ° C. to 200 ° C. for 2 hours to 6 hours. There is no need to control the atmosphere, for example, in the air. When heated under these conditions, the carbon nitride precursor can be reliably polymerized.

  Step S250: heating the macro mesopore template 360 with the polymerized carbon nitride precursor 380, carbonizing the polymerized carbon nitride precursor 380, and particles 300 and blocks from the macro mesopore template 360. Copolymer 340 is removed. By heating, the polymerized carbon nitride precursor 380 is carbonized to become carbon nitride 390. Further, the particles 300 and the block copolymer 340 are burned out from the macro mesopore template 360 by heating.

  Here, macropores 312 are formed by burning out the particles 300. Further, silica 313 with mesopores remains due to the block copolymer 340 being burned out.

  Specifically, the macro mesopore template 360 having the polymerized carbon nitride precursor 380 is heated by heating in a temperature range of 400 ° C. to 600 ° C. for 2 hours to 6 hours in an inert atmosphere. Is called. By heating under this condition, the polymerized carbon nitride precursor 380 can be carbonized, and only the particles 300 and the block copolymer 340 can be reliably removed from the macro mesopore template 360. If it exceeds 600 ° C., the nitrogen content is lowered, and carbon nitride may not be formed. When the temperature is lower than 300 ° C., the particles 300 and the block copolymer 340 may remain. The inert atmosphere is an argon atmosphere, a nitrogen atmosphere, or the like.

  In addition, by appropriately selecting a temperature within the above temperature range, the nitrogen atom and the ratio of nitrogen atom to carbon atom (N / (C + N)) in the finally obtained porous carbon nitride film of the present invention can be controlled. . For example, the nitrogen content can be reduced by selecting the high temperature side, and the nitrogen content can be increased by selecting the low temperature side. The specific N / (C + N) ratio (atomic%) can be controlled in the range of 10% to 25% depending on the temperature range.

  Step 260: Particle 300 and block copolymer 340 are removed, and a product composed of carbonized carbon nitride precursor (carbon nitride 390) and silica (silica 313 with mesopores) is treated with acid or alkali to produce silica. Remove. Silica reacts with acids or alkalis and is etched away.

  The mesopores 314 are formed by etching and removing silica (silica 313 with mesopores). The final carbon nitride 380 is the frame structure 110 (FIG. 1).

  The acid or alkali used for the acid or alkali treatment is hydrofluoric acid or sodium hydroxide. These are both strong acids and strong alkalis, react with silica, and the silica is etched.

  In this way, the porous carbon nitride film 100 of the present invention is obtained on the substrate 320. If the method of the present invention is adopted, the arrangement of the macropores 120 in the porous carbon nitride film 100 reflects the arrangement of the particles 300 in the macropore template 310, so that the regular arrangement of the macropores 120 is easy. Can be achieved. If the method of the present invention is employed, the mesopores 130 are generated by using the block copolymer 340 having a desired shape and size. Therefore, in addition to the macropores 120, the shape and size of the mesopores 130 are formed. It is possible to obtain a bimodal porous carbon nitride film in which the above is controlled.

  Although FIG. 3 shows the macropore template 310 in which only one layer of particles 300 is arranged on the substrate 320, the macropore template 310 used in step S210 is not limited to this. For example, a template in which particles 300 are arranged in multiple layers may be used as the macropore template 310. Thereby, a multilayer porous carbon nitride film having a large thickness can be obtained.

  Next, since the porous carbon nitride film 100 on the substrate 320 thus obtained is a self-supporting film, it can be easily transferred to a desired base material.

  S310: The porous carbon nitride film 100 on the substrate 320 is immersed in water. Thereby, the porous carbon nitride film 100 peels from the substrate 320 and is adsorbed on the water surface.

  S320: The porous carbon nitride film 100 adsorbed on the water surface is brought into contact with another substrate. Thereby, the porous carbon nitride film 100 is easily transferred to another substrate. Here, the another base material is made of an arbitrary material, may be a flat surface, may be curved, may have a curvature, and may be a base material having an arbitrary shape.

(Embodiment 3)
In Embodiment 3, the use of the porous carbon nitride film of the present invention is illustrated.

  FIG. 4 is a schematic view showing a filter using the porous carbon nitride film of the present invention.

  The filter 400 includes the porous carbon nitride film 100 of the present invention. Since porous carbon nitride film 100 has been described in detail in the first embodiment, description thereof is omitted. Here, the porous carbon nitride film 100 is selected from the group consisting of metals such as Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt, Au and / or lanthanoid metals. It further includes a selected metal.

  The operation of the filter 400 will be described. Here, it is assumed that the pore diameter of the macropores 120 (FIG. 1) of the porous carbon nitride film 100 is about 400 nm, the pore diameter of the mesopores is about 10 nm, and the gas 410 has about 400 nm and about 10 nm. It shall contain two types of toxic substances of different sizes.

  A gas 410 containing harmful substances passes through the filter 400. Since the size of the harmful substance in the gas 410 coincides with the pore diameters of the macropores and the mesopores in the porous carbon nitride film 100 of the filter 400, the harmful substances in the gas 410 in the filter 400 become macropores. And trapped in the mesopores. The trapped harmful substances are decomposed and processed by the metal in the carbon nitride film 100. In this way, the gas 420 from which harmful substances have been removed is sent out from the filter 400.

  FIG. 4 shows an example in which the porous carbon nitride film 100 contains a metal having a catalytic action. However, the porous carbon nitride film 100 is used for simply capturing a substance in the macropores and mesopores of the porous carbon nitride film 100. When doing, it does not need to contain the metal which has a catalytic action.

  Since the porous carbon nitride film 100 of the present invention has an adsorbing ability to aromatic hydrocarbons, acidic solvents and the like immediately after production, a specific substance is sensed using the porous carbon nitride film 100 of the present invention. A sensor may be constructed. Among these substances, the porous carbon nitride film 100 of the present invention is suitable as a sensor for sensing aniline or acetic acid because it has an excellent adsorption ability for aniline and acetic acid.

  Further, the adsorption ability of the porous carbon nitride film 100 of the present invention can be controlled by ozone treatment. When the porous carbon nitride film 100 of the present invention is subjected to ozone treatment (ozone irradiation), it is possible to increase the adsorption ability for a substance having an amine (for example, aniline). In a specific ozone treatment, it is desirable to hold the porous carbon nitride film 100 for at least 15 minutes in oxygen, an ultraviolet lamp and nitrogen using an ozone cleaner or the like. If it is shorter than 15 minutes, the effect of ozone treatment cannot be expected. Such an ozone-treated porous carbon nitride film 100 may be used.

  The present invention will now be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples.

  In Example 1, a single-layer colloidal crystal composed of particles (polystyrene) 300 (FIG. 3) having a particle size of 476 nm was used as the macropore template 310 (FIG. 3), and tetraethoxy was used as the silica source 330 (FIG. 3). The porous structure of the present invention uses silane (TEOS), P123 as a block copolymer 340 (FIG. 3), polyethyleneimine as a carbon nitride precursor, hydrochloric acid as an acid, and a Si substrate as a substrate 320 (FIG. 3). A carbon nitride film was produced.

  P123 (0.5 g) and water (5 g) were mixed and stirred at room temperature for 4 hours. Next, 2M hydrochloric acid (15 g) was added thereto, and the mixture was stirred at 40 ° C. for 2 hours. Further, TEOS (1.5 g) was added thereto and stirred at 40 ° C. for 15 minutes. Thus, the 1st solution containing TEOS and P123 was prepared.

  Next, the macropore template, which is a colloidal crystal in which particles are arranged in a single layer on a Si substrate, was heated at 100 ° C. for 10 minutes to improve the adhesion between the Si substrate and the particles (colloidal crystal). The macropore template was immersed in the first solution for about 3 minutes, and the first solution was applied to the macropore template (step S210 in FIG. 2).

  The macroporous template to which the first solution was applied was heated in the atmosphere at 100 ° C. for 24 hours to generate silica from TEOS (step S220 in FIG. 2). Thereby, a macro mesopore template 360 (FIG. 3) having a macropore template 310 made of particles and a mesopore template 350 made of silica and P123 was formed.

  A second solution in which polyethyleneimine (molecular weight 2000, 30 wt%) was dissolved in distilled water was prepared. The second solution was added dropwise to the macro mesopore template (step S230 in FIG. 2). The macro-mesopore template to which the second solution was applied was heated in the atmosphere at 100 ° C. for 6 hours and then at 160 ° C. for 6 hours to polymerize the polyethyleneimine in the second solution (FIG. 2). Step S240).

  Next, the macro-mesopore template having polymerized polyethyleneimine was heated to 450 ° C., 500 ° C., 550 ° C. and 600 ° C. at a heating rate of 3 ° C./min, and heated in an argon atmosphere for 5 hours. The polymerized polyethyleneimine was carbonized (step S250 in FIG. 2). With this heating, the particles and P123 were burned off.

  The remaining polymerized / carbonized polyethyleneimine and silica product was treated with hydrofluoric acid (10 wt%) for 2 hours to etch and remove the silica (step S260 in FIG. 2).

Thin film samples carbonized at 450 ° C., 500 ° C., 550 ° C. and 600 ° C. on the Si substrate thus obtained (hereinafter referred to as thin film 1 or thin film 1 for each sample) ₄₅₀ , thin film 1 ₅₀₀ , thin film 1 ₅₅₀ , and thin film 1 ₆₀₀ ) were examined for structure, physical properties, and the like.

  The morphology of the thin film 1 was observed with a field emission scanning electron microscope FESEM (Hitachi, S-4800). The observation results are shown in FIG. The microstructure of the thin film 1 was observed with a field emission transmission electron microscope TEM (JEOL, JEM-2100F) equipped with Gatan-776 electron energy loss spectroscopy (EELS). The observation results are shown in FIG. The results of mapping by EELS and the ratio of nitrogen atom to nitrogen atom and carbon atom (N / (C + N)) calculated from EELS are shown in FIGS. 9 and 12, respectively.

  The X-ray diffraction pattern of the thin film 1 was measured with an X-ray diffractometer (Rigaku) using CuKα rays (λ = 0.154 nm). The measurement results are shown in FIG. X-ray photoelectron spectroscopy (XPS) analysis of the thin film 1 was performed using a Perkin-Elmer PHI-5600ci. The results are shown in FIG.

  The infrared absorption spectrum of the thin film 1 was measured with an infrared spectrometer (Nicolet Nexus 670). The measurement results are shown in FIG.

  The adsorption ability of the thin film 1 for various substances was measured using a quartz crystal balance QCM (USI system). For measurement, a QCM resonator coated with silver on both sides was used as an electrode, and a shift amount (change amount) of one frequency corresponded to a mass change of about 0.95 ng. The thin film 1 was immersed in water and peeled from the Si substrate (step S310). The thin film 1 (0.3 μg) adsorbed on the water surface was brought into contact with the QCM resonator and transferred (step S320). From the transfer of the thin film 1 to these QCM resonators, it was confirmed that the film obtained by the production method of the present invention is a self-supporting film and can be easily transferred to a desired substrate.

  The QCM resonator to which the thin film 1 was transferred was set as a resonator holder in the QCM device. As various substances, 10 mL of a volatile liquid (aniline as an aromatic hydrocarbon and acetic acid as an acidic solvent) was prepared in a glass container. This was set in the QCM device. In order to prevent leakage due to vaporization, the QCM device was completely covered with a cover during the measurement of the adsorption capacity. After measuring the adsorptive capacity, the cover and the glass container containing the volatile liquid were removed, and the thin film 1 was exposed to the atmosphere. The adsorption capacity was measured at 25 ° C. The measurement results are shown in FIGS.

  Next, the thin film 1 was subjected to ozone treatment. For the ozone treatment, an ozone cleaner (Filgen, UV253S system) was used, and oxygen, an ultraviolet lamp and nitrogen were introduced. The ozone treatment time was 15 minutes. The adsorption ability of the thin film 1 after ozone treatment to aniline and acetic acid was measured under the same conditions using the above-mentioned QCM apparatus. The measurement results are shown in FIG.

  In Example 2, a single-layer colloidal crystal composed of particles (made of polystyrene) having a particle size of 200 nm was used as the macropore template 310, and carbonized at 450 ° C. in the same procedure as in Example 1, The inventive porous carbon nitride film was produced. The thin film sample (hereinafter simply referred to as the thin film 2) obtained on the Si substrate obtained in Example 2 was observed by SEM in the same manner as in Example 1. The observation results are shown in FIG.

  In Example 3, a single-layer colloidal crystal composed of particles (made of polystyrene) having a particle size of 1000 nm (1 μm) was used as the macropore template 310, and carbonized at 450 ° C., and the same procedure as in Example 1 Thus, the porous carbon nitride film of the present invention was produced. The thin film sample (hereinafter simply referred to as the thin film 3) obtained on the Si substrate obtained in Example 3 was observed by SEM in the same manner as in Example 1. The observation results are shown in FIG.

Table 1 shows the production conditions of Examples 1 to 3 described above.

FIG. 5 is a view showing an SEM image of the thin film ₁₄₅₀ according to the first embodiment.

According to FIGS. 5A and 5B, it was confirmed that the thin film 1 ₄₅₀ is formed by the frame structure 510, and the frame structure 510 has the macropores 520. The thickness (wall thickness) of the frame structure 510 between the macropores 520 was 80 nm, and the thickness of the thin film ₁₄₅₀ was about 300 nm.

Further, according to FIG. 5A, the macropores 520 are regularly arranged in the surface direction of the thin film ₁₄₅₀ , and the arrangement of the colloidal crystal particles of the close-packed-like macropore template 310 is as follows. It was the same. Furthermore, according to FIG. 5A, the macropores 520 had an opening on the outermost surface of the thin film ₁₄₅₀ . The pore diameter of the macropores 520 was 470 nm, which coincided with the particle diameter (476 nm) of the macropore template 310 used for production.

FIG. 6 is a view showing a TEM image of the thin film ₁₄₅₀ according to the first embodiment.

  FIG. 6 shows details of the macropores 520. According to FIGS. 6A and 6B, it was confirmed that the macropores 520 are hemispherical having curved wall surfaces. Further, according to FIG. 6B, concentric channels 610 were confirmed on the hemispherical wall surface of the macropore 520. The channel 610 was a mesopore (130 in FIG. 1) and was found to reflect well the shape of P123 used for the template.

Although not shown, similar results were obtained for the thin film 1 ₅₀₀ , the thin film 1 _550, and the thin film 1 ₆₀₀ .

  From the above, if the method of the present invention is adopted, bimodal porosity comprising a frame structure having macropores reflecting the arrangement and size of particles and mesopores reflecting the shape of the block copolymer A thin film was shown to be obtained. This suggests that since the porous thin film of the present invention has macropores and mesopores, it has a large surface area and a large pore volume, and can be used for catalysts, adsorbents, and filters. .

  FIG. 7 is a diagram showing SEM images of thin films 2 and 3 according to Examples 2 and 3.

  7A and 7B are SEM images of the thin film 2, and FIGS. 7C and 7D are SEM images of the thin film 3. According to FIG. 7, both the thin films 2 and 3 were in the same manner as the thin film 1. The pore diameter of the macropore 710 of the thin film 2 was about 200 nm, and the pore diameter of the macropore 720 of the thin film 3 was about 1000 nm (1 μm). Each of these pore sizes matched the particle size of the particles used in the macropore template. Although not shown, it was confirmed by TEM that the thin films 2 and 3 also have mesopores. The film thicknesses of the thin films 2 and 3 were each slightly smaller than the particle size of the selected particles, but were the same size as the particle size.

  From the above, it has been shown that a porous thin film in which the pore diameter of the obtained macropores is controlled can be obtained by changing the particle size of the macropore template particles.

FIG. 8 is a view showing an XRD pattern of the thin film ₁₄₅₀ according to the first embodiment.

According to FIG. 8, the thin film 1 ₄₅₀ showed reflection at 25.8 ° (2θ) corresponding to a lattice spacing of 0.342 nm. This reflection was attributed to the (002) of the graphite-like material due to the turbulent arrangement of carbon and nitrogen atoms in the graphene layer. This suggests that thin film 1 ₄₅₀ is graphitic carbon nitride. Although not shown, similar results were obtained for the thin film 1 ₅₀₀ , the thin film 1 _550, and the thin film 1 ₆₀₀ .

FIG. 9 is a diagram showing an EELS mapping image of the thin film ₁₄₅₀ according to the first embodiment.

  9A is a bright field image, FIG. 9B is a mapping image of carbon atoms, FIG. 9C is a mapping image of nitrogen atoms, and FIG. 9D is an EELS spectrum. .

FIG. 9A shows a frame structure having macropores as in FIGS. In FIGS. 9B and 9C, the bright portions of contrast indicate carbon atoms and nitrogen atoms. The carbon atom and nitrogen atom patterns in the thin film 1 ₄₅₀ all had the same morphology as that in FIGS. 9 (a), 5 and 6. From this, it was found that carbon atoms and nitrogen atoms were uniformly distributed both outside and inside the thin film ₁₄₅₀ . This is considered to be an effect of imparting a single polyethyleneimine, which is a liquid phase, to the macro mesopore template as a carbon nitride precursor in the method of the present invention.

According to FIG. 9D, the thin film 1 ₄₅₀ showed peaks at 284 eV that is the CK edge and 401 eV that is the NK edge. The peak at 284 eV is due to 1s-π * electron transition and is due to sp2 hybrid carbon bonded to the nitrogen atom. This is caused by the high electronegativity of nitrogen, which reduces the electron density at the carbon atom.

  The state of the peak at the NK edge was the same as that at the CK edge. This also suggests that the nitrogen atom forms an sp2 hybrid with the carbon atom.

The N / (C + N) ratio (atomic%) was determined from carbon atoms and nitrogen atoms from FIG. 9 (d), and was about 23%. Although not shown, similar EELS spectra were obtained for the thin film 1 ₅₀₀ , the thin film 1 ₅₅₀ and the thin film 1 ₆₀₀ although the N / (C + N) ratio was different.

  From the above, it was shown that if the method of the present invention is adopted, a porous carbon nitride film having a frame structure having macropores and mesopores, the frame structure being made of carbon nitride, can be obtained.

FIG. 10 is a diagram showing an XPS spectrum of the thin film ₁₄₅₀ according to Example 1.

FIG. 10A shows the C1s spectrum, and FIG. 10B shows the N1s spectrum. According to FIG. 10A, the thin film 1 ₄₅₀ has peaks at 284.2 eV, 285.4 eV, and 288.1 eV, and it was found that three types of carbon atoms exist. The peak at 284.2 eV is due to pure graphite sites in amorphous carbon nitride. The peak at 285.4 eV is attributed to the sp2 carbon atom bonded to the nitrogen atom in the aromatic structure. The peak at 288.1 eV is due to the sp2 hybrid carbon atom in the aromatic ring attached to the NH ₂ group.

According to FIG. 10B, the thin film 1 ₄₅₀ has peaks at 398.0 eV and 400.1 eV, and it was found that different nitrogen bonding states exist in the C—N bond. The peak at 398.0 eV is attributed to the nitrogen atom sp 2 bonded to the carbon atom, more specifically the nitrogen atom in the C═N—C group. The peak at 400.1 eV is attributed to all sp2 carbon atoms or nitrogen atoms bonded in three directions to two sp2 carbon atoms in the amorphous CN network. These results agreed well with the results of the C1s spectrum shown in FIG.

From the above, it was shown that if the method of the present invention is employed, a porous carbon nitride film that is amorphous carbon nitride can be obtained. Although not shown, similar results were obtained for the thin film 1 ₅₀₀ , the thin film 1 _550, and the thin film 1 ₆₀₀ . Further, the nitrogen atom ratio (N / (C + N)) (atomic%) to carbon atoms and nitrogen atoms in the thin film ₁₄₅₀ calculated from FIG. 10 was about 23%, which coincided with the value obtained by EELS.

FIG. 11 is a diagram showing an FTIR spectrum of the thin film ₁₄₅₀ according to Example 1.

The FTIR spectrum shown in FIG. 11 was the same spectrum as other carbon nitride materials. In particular, the absorption between the wave number 500 cm ^-1 and a wavenumber 950 cm ^-1 becomes IR activity by incorporating a nitrogen atom in the network, due to out-of-plane deformation mode of graphitic sp2 domain. Absorption at wavenumber 1436m ⁻¹ is due to the aromatic C—N stretching mode. Absorption at wave number 1620m ⁻¹ is due to the C = N stretching mode. The broad absorption at wave numbers 3150 m ^{−1 to} 3500 cm ⁻¹ is attributed to the NH ₂ group or NH group stretching mode in aromatics. The minute absorption at a wave number of about 2200 cm ⁻¹ is due to the C≡N stretching mode. The absorption band characteristic of the main IR coincided with the general absorption band of other amorphous carbon nitride materials.

Although not shown, similar results were obtained for the thin film 1 ₅₀₀ , the thin film 1 _550, and the thin film 1 ₆₀₀ . From this, it was confirmed that the porous thin film obtained by the method of the present invention was made of carbon nitride.

  FIG. 12 is a graph showing the heating temperature dependence of the N / (C + N) ratio of the thin film 1 according to Example 1.

  In FIG. 12, the heating temperature is the carbonization temperature in step S250 of FIG. The ratio (atomic%) of nitrogen atoms to nitrogen atoms and carbon atoms in the thin film 1 was calculated from the spectrum of EELS.

  As can be seen from FIG. 12, the lower the carbonization temperature, the higher the nitrogen content, and the higher the carbonization temperature, the lower the nitrogen content. Specifically, N / (C + N) changed from 22 to 12 when the carbonization temperature was increased from 450 ° C to 600 ° C. The decrease in nitrogen content is expected to result from the burning out of nitrogen atoms from the polymerized carbon nitride precursor obtained in step S240 of FIG. 2 with increasing carbonization temperature.

  From the above, it was confirmed that the amount of nitrogen in the obtained porous carbon nitride film can be controlled by controlling the carbonization temperature within a temperature range of 400 ° C. to 600 ° C.

FIG. 13 is a diagram showing the time dependency of the QCM frequency shift amount for aniline and acetic acid of the thin film 1 ₄₅₀ according to Example 1. FIG.

In FIG. 13, profiles a and b show QCM frequency changes (shift amounts) for aniline and acetic acid, respectively. All profiles showed QCM frequency changes over time. From this, it was confirmed that the thin film ₁₄₅₀ can adsorb | suck an aromatic hydrocarbon and an acidic solvent.

More specifically, thin film 1 ₄₅₀ had a higher adsorption capacity for acetic acid, which was about 6 times that of aniline. This is because the frame structure in the porous carbon nitride film according to the present invention is a structure in which a basic nitrogen group element is incorporated in a carbon frame structure such as NH, NH ₂ or N bonded to a carbon atom. I think that.

  From this, the porous carbon nitride film of the present invention can be a sensor for sensing a specific substance, preferably an aromatic hydrocarbon or an acidic solvent, more preferably a sensor for sensing acetic acid. It has been shown.

FIG. 14 is a diagram showing the QCM frequency shift amount with respect to aniline and acetic acid of the thin film ₁₄₅₀ before and after the ozone treatment according to Example 1 (treatment time 15 minutes).

The QCM frequency shift amount before ozone treatment in FIG. 14 is based on the results in FIG. According to FIG. 14, the thin film 1 ₄₅₀ after the ozone treatment had adsorption ability in the order of aniline and then acetic acid. This order of adsorption capacity was reversed from that before ozone treatment.

  Since the adsorption ability can be changed by the ozone treatment, that is, the sensing substance can be controlled, the porous carbon nitride film of the present invention may be used as an optical switch.

  Further, the adsorption experiment shown in FIGS. 13 and 14 was repeated a plurality of times, but no substantial change was observed in the adsorption amount. From this, it was confirmed that the porous carbon nitride film of the present invention has high stability and is commercially advantageous.

  Since the porous carbon nitride film of the present invention has macropores and mesopores, it can be used for catalysts, adsorbents, filters, and the like. Since the porous carbon nitride film of the present invention has a selective adsorption ability for a predetermined substance, it is suitable for a sensor or an optical switch. Further, the porous carbon nitride film of the present invention may be used for gas separation, chromatography, and energy storage, in addition to the above-mentioned applications, similarly to the existing porous materials.

100 Porous carbon nitride film 110, 510 Frame structure 120, 312, 520, 710, 720 Macropore 130, 314 Mesopore 140 Opening 300 Particle 310 Macropore template 320 Substrate 330 Silica source 340 Block copolymer 350 Mesopore template 360 Macro mesopore template 370 Second solution 380 Carbon nitride precursor 390 Carbon nitride 313 Silica with mesopores 400 Filter 410 Gas containing harmful substance 420 Gas from which harmful substance has been removed 610 Channel

JP 2006-124250 A JP 2010-030844 A International Publication No. 2008/126799 Pamphlet

Claims (20)

A porous carbon nitride film formed by a frame structure made of carbon nitride,
The frame structure is
Macropores,
And mesopores having a pore size smaller than the pore size of the macropores,
The macropores are regularly arranged in the surface direction of the porous carbon nitride film,
The macropores are porous carbon nitride films having openings on the surface of the porous carbon nitride film.   The porous carbon nitride film according to claim 1, wherein a pore diameter of the macropores is in a range of 50 nm to 15 μm.   The porous carbon nitride film according to claim 1, wherein a pore diameter of the mesopores is in a range of 5 nm to 20 nm.   The carbon nitride contains a metal element and / or a lanthanoid element selected from the group consisting of Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt, and Au. The porous carbon nitride film according to claim 1.   The porous carbon nitride film according to claim 1, wherein the carbon nitride is amorphous carbon nitride.   2. The porous carbon nitride film according to claim 1, wherein an N / (C + N) ratio (atomic%) of nitrogen atoms N and carbon atoms C in the carbon nitride is in a range of 10% to 25%. A method for producing the porous carbon nitride film according to claim 1, comprising:
Applying a first solution containing a silica source and a block copolymer to a macroporous template comprising particles;
Heating the macropore template to which the first solution has been applied to produce silica from the silica source; and the macropore template, and the mesopore template comprising the block copolymer and the silica. Forming a macro mesopore template having:
Applying a second solution containing a carbon nitride precursor to the macro mesopore template;
Heating the macro mesopore template provided with the second solution to polymerize the carbon nitride precursor;
Heating the macro mesopore template having the polymerized carbon nitride precursor, carbonizing the polymerized carbon nitride precursor, and from the macro mesopore template, the particles and the blocks Removing the copolymer;
Removing the particles, the block copolymer, treating the carbonized carbon nitride precursor and the product comprising the silica with an acid or alkali, and removing the silica.   The method of claim 7, wherein the silica source is tetraethoxysilane (TEOS) or sodium silicate.   8. The method of claim 7, wherein the block copolymer is selected from the group consisting of P104, P123, F108 and F127.   The method of claim 7, wherein the carbon nitride precursor is selected from the group consisting of polyethyleneimine, aniline, melamine and ethylenediamine.   The second solution contains metal ions and / or lanthanoid ions selected from the group consisting of Al, Ti, Cr, Fe, Co, Ni, Cu, Mo, Pd, Ag, Ta, W, Pt, and Au. The method of claim 7.   The method according to claim 7, wherein the particle size is in the range of 50 nm to 15 μm.   The method according to claim 7, wherein the step of generating silica heats the macroporous template to which the first solution has been applied in a temperature range of 80 ° C. to 150 ° C. for 12 hours to 36 hours.   The step of polymerizing the carbon nitride precursor comprises subjecting the macro mesopore template provided with the second solution to a first temperature range of 50 ° C. to 100 ° C. for 2 hours to 6 hours, The method according to claim 7, wherein the heating is performed at a temperature range of 160C to 200C higher than the first temperature range for 2 hours to 6 hours.   The carbonizing and removing step comprises heating the macro mesopore template having the polymerized carbon nitride precursor in a temperature range of 400 ° C. to 600 ° C. for 2 hours to 6 hours in an inert atmosphere. The method of claim 7.   The method according to claim 7, wherein the acid or alkali treatment uses hydrofluoric acid or sodium hydroxide.   The method of claim 7, wherein the macropore template is a colloidal crystal.   8. The method of claim 7, further comprising the step of ozone treating the porous carbon nitride film following the step of removing the silica.   A sensor comprising the porous carbon nitride film according to claim 1.   A filter comprising the porous carbon nitride film according to claim 1.