JP2022018134A - Fullerene nanosheet, its manufacturing method and crystal oscillator gas sensor using it - Google Patents

Abstract

[Problem] To provide a functional fullerene nanosheet, a method for producing the same, and a crystal oscillator gas sensor using the same. SOLUTION: The fullerene nanosheet of the present invention contains fullerene as a main component, contains nitrogen atoms, has a hexagonal plate-like structure, and is porous. Fullerene nanosheets have a face-centered cubic lattice structure (FCC) and are hydrophilic. The diameter of the hexagonal plate-like structure is in the range of 1 μm or more and 3 μm or less, and the thickness of the hexagonal plate-like structure is in the range of 300 nm or more and 1 μm or less. [Selection diagram] Figure 1A

Description

Application for application of Article 30, Paragraph 2 of the Patent Act (1) Published on December 3, 1st year of Reiwa Published by ROYAL SOCIETY OF CHEMISTRY Materials Horizons, 2020, vol. 7,787-795 DOI: 10.1039 / c9mh01866b (2) Published March 2, 2nd year of Reiwa The 13th MANA International Symposium 2020 jointly with ICYS Proceedings P. 9

The present invention relates to a fullerene nanosheet, a method for producing the same, and a crystal oscillator gas sensor using the same.

In recent years, fullerene nanosheets have been reported by a liquid-liquid interface precipitation method (LLIP method) (see, for example, Non-Patent Document 1). According to Non-Patent Document 1, it is reported that a fullerene _nanosheet composed of C60 is produced at the interface between carbon tetrachloride and isopropanol. It is expected that such fullerene nanosheets will be further improved and new applications using them will be expected.

Marappan Sathish et al., J. Mol. Am. Chem. Soc. , 2007,129,13816-13817

From the above, it is an object of the present invention to provide a fullerene nanosheet having functionality, a method for producing the same, and a crystal oscillator gas sensor using the same.

The fullerene nanosheet containing fullerene as a main component of the present invention has a hexagonal plate-like structure and is porous, and the fullerene contains a nitrogen atom, thereby solving the above-mentioned problems.
The fullerene is selected from at least one group consisting of C ₆₀ fullerene, C ₇₀ fullerene, C ₇₆ fullerene, C ₇₈ fullerene, C ₈₂ fullerene, C ₈₄ fullerene, C ₉₀ fullerene, C ₉₄ fullerene, and derivatives thereof. May be.
The fullerene may be _C60 fullerene and / or a derivative thereof.
It may have a face-centered cubic lattice structure (fcc).
It may have hydrophilicity.
The diameter of the hexagonal plate-shaped structure may be in the range of 1 μm or more and 4 μm or less, and the thickness of the hexagonal plate-shaped structure may be in the range of 300 nm or more and 1 μm or less.
In the FTIR spectrum measured by the Fourier transform infrared spectroscopic altimeter, a peak due to NH expansion and contraction vibration may be present in the range of 3000 cm ^-1 or more and 3450 cm ^-1 or less.
In the XPS spectrum measured by X-ray photoelectron spectroscopy, the N1s peak of nitrogen may be present in the range where the binding energy is 398.5 eV or more and 400.5 eV or less.
The nitrogen atom may be contained in the range of 4 atomic% or more and 10 atomic% or less.
The nitrogen atom may be oxidized.
The surface of the fullerene nanosheet may be aminated.
The method for producing the fullerene nanosheet according to the present invention comprises mixing a fullerene dispersion in which fullerene is dispersed in p-xylene and a lower alcohol having 5 or less carbon atoms to form a fullerene nanosheet by a liquid-liquid interfacial precipitation method. Add ethylenediamine in the range of 2 wt% or more and 10 wt% or less with respect to the total of the p-fullerene and the lower alcohol to obtain a mixed solution, and incubate the mixed solution for a time of 5 minutes or more and 30 minutes or less. And, thereby solving the above-mentioned problems.
Following the incubation may further include washing the product with the mixed solution of p-xylene, lower alcohol and ethylenediamine.
The lower alcohol may be selected from at least one group consisting of methanol, ethanol, propanol, and isopropanol.
The fullerene nanosheet may be formed by ultrasonic treatment.
The mixed solution may be obtained while performing ultrasonic treatment.
The fullerene may be _C60 fullerene and / or a derivative thereof.
In the crystal oscillator gas sensor provided with the gas sensor membrane according to the present invention, the gas sensor membrane contains the fullerene nanosheet, thereby solving the above-mentioned problems.
Acid gases selected from the group consisting of formic acid, acetic acid and propionic acid may be detected.

Since the fullerene nanosheet of the present invention contains nitrogen, it has hydrophilicity. As a result, the fullerene nanosheets of the present invention have excellent dispersibility in water and can be applied to bio-related applications. Since the fullerene nanosheet of the present invention has a hexagonal plate-like structure and is porous, it can be applied to bio-related applications such as encapsulation, transportation, and release of nanometer-sized and submicron-sized objects using pores. Is expected. In addition, the fullerene nanosheets of the present invention show excellent selectivity for volatile acid gases. Therefore, the fullerene nanosheet of the present invention can be used for a crystal oscillator gas sensor.

According to the method for producing fullerene nanosheets of the present invention, the fullerene nanosheets having the above-mentioned hydrophilicity and high functionality can be obtained without newly performing a hydrophilic treatment, so that the production process can be simplified. It is advantageous.

Schematic diagram showing the fullerene nanosheet of the present invention Schematic diagram showing an exemplary fullerene constituting the fullerene nanosheet of the present invention. A flowchart showing a process of manufacturing the fullerene nanosheet of the present invention. Front view of crystal oscillator gas sensor using fullerene nanosheet of the present invention Side view of the crystal oscillator gas sensor using the fullerene nanosheet of the present invention The figure which shows the SEM image of the fullerene nanosheet obtained by the step S210 of FIG. The figure which shows the diameter distribution of a fullerene nanosheet The figure which shows the STEM image of a fullerene nanosheet. The figure which shows the SEM image of the sample of Example 1. The figure which shows the STEM image of the sample of Example 1. The figure which shows the diameter distribution of the sample of Example 1. The figure which shows the TEM image and the HRTEM image of the sample of Example 1. The figure which shows the XRD pattern of the sample of Example 1. The figure which shows the Raman spectrum of the sample of Example 1. The figure which shows the FTIR spectrum on the high frequency side of the sample of Example 1. The figure which shows the FTIR spectrum on the low frequency side of the sample of Example 1. The figure which shows the UV-vis spectrum of the sample of Example 1. The figure which shows the XPS spectrum of the sample of Example 1. The figure which shows the XPS spectrum of the N1s core level of the sample of Example 1. The figure which shows the QCM frequency shift for various volatile organic compounds by the QCM sensor of Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements are designated by the same reference numerals, and the description thereof will be omitted.

(Embodiment 1)
In the first embodiment, the fullerene nanosheet of the present invention and a method for producing the same will be described in detail.
FIG. 1A is a schematic view showing a fullerene nanosheet of the present invention.
FIG. 1B is a schematic diagram showing an exemplary fullerene constituting the fullerene nanosheet of the present invention.

As schematically shown in FIG. 1A, the fullerene nanosheet 100 of the present invention has a hexagonal plate-like structure and is porous with mesopores 110.

The fullerene nanosheet 100 of the present invention contains fullerene as a main component. In the present specification, the fullerene is not particularly limited as long as it is a spherical molecule containing a carbon atom having and / or not having a substituent, but, as an example, C ₆₀ fullerene and C ₇₀ fullerene. , C ₇₆ fullerene, C ₇₈ fullerene, C ₈₂ fullerene, C ₈₄ fullerene, C ₉₀ fullerene, C ₉₄ fullerene, and at least one selected from the group consisting of derivatives thereof. The fullerene derivative means a compound in which at least a part of fullerene is modified.

Among them, fullerene is more preferably _C60 fullerene and / or a derivative thereof. As a result, nanosheets can be produced in high yield by the method described later. When the fullerene is C ₆₀ , the fullerene nanosheets of the present invention preferably have a face-centered cubic lattice structure (fcc).

In the present specification, the term "fullerene as a main component" means that the X-ray diffraction pattern does not have a clear diffraction peak other than fullerene, but in the example, the fullerene nanosheet is 90% by mass or more, preferably 95. It means that it contains fullerene in mass% or more.

In the fullerene nanosheet 100 of the present invention, fullerene contains a nitrogen atom. The nitrogen atom may be substituted with a carbon atom constituting fullerene, or may be contained in a substituent modified to fullerene. The fullerene nanosheet 100 is hydrophilic due to the nitrogen atom.

The nitrogen atom is preferably contained in the range of 4 atom% or more and 10 atom% or less. This shows high hydrophilicity. The nitrogen atom is more preferably contained in the range of 5 atom% or more and 7 atom% or less. As a result, it exhibits even higher hydrophilicity. The nitrogen atom content is measured by X-ray photoelectron spectroscopy (XPS).

The fullerene nanosheet 100 of the present invention preferably has a peak due to NH expansion and contraction vibration in the range of 3000 cm ^-1 or more and 3450 cm ^-1 or less in the FTIR spectrum measured by a Fourier transform infrared spectroscopic altimeter. By having a peak caused by this NH expansion and contraction vibration, hydrophilicity can be exhibited.

The fullerene nanosheet 100 of the present invention more preferably has a peak due to NH expansion and contraction vibration in the range of 3300 cm ^-1 or more and 3350 cm ^-1 or less in the FTIR spectrum measured by a Fourier transform infrared spectroscopic altimeter. Thereby, high hydrophilicity can be exhibited.

The fullerene nanosheet 100 of the present invention preferably has an N1s peak of nitrogen in the range where the binding energy is 398.5 eV or more and 400.5 eV or less in the XPS spectrum measured by X-ray photoelectron spectroscopy. This allows for high hydrophilicity. More preferably, the nitrogen atom contained in the fullerene nanosheet 100 of the present invention is preferably oxidized. This stabilizes the nitrogen atom. It should be noted that the presence of such oxidized nitrogen atoms may be solved by unconvolution of the peak at the core level of N1s in the XPS spectrum.

The surface of the fullerene nanosheet 100 of the present invention is preferably aminated, as shown in FIG. 1B. FIG. 1B shows an example of _C60 as a fullerene, but the present invention is not limited to this. By reacting ethylenediamine used as a raw material with fullerene in the production method described later, the surface is amination, so that high hydrophilicity can be exhibited. Surface amination can be identified by mass spectrum.

As a matter of course, the fullerene nanosheet 100 of the present invention may contain oxidized nitrogen, the surface may be amination, or both.

The hexagonal plate-like structure of the fullerene nanosheet 100 of the present invention preferably has the following sizes.
The diameter is in the range of 1 μm or more and 4 μm or less.
The thickness is in the range of 300 nm or more and 1 μm or less.
Having such a size shows high selectivity for acid.

The hexagonal plate-like structure of the fullerene nanosheet 100 of the present invention more preferably has the following sizes.
The diameter is in the range of 1 μm or more and 2 μm or less.
The thickness is in the range of 400 nm or more and 600 nm or less. Having such a size shows even higher selectivity for acids.

Next, a method for producing the fullerene nanosheet of the present invention will be described.
FIG. 2 is a flowchart showing a process of manufacturing the fullerene nanosheet of the present invention.

The fullerene nanosheets of the present invention are produced by the following steps S210 to S230.
Step S210: A fullerene dispersion in which fullerene is dispersed in p-xylene and a lower alcohol having 5 or less carbon atoms are mixed to form fullerene nanosheets by a liquid-liquid interfacial precipitation method.
Step S220: Ethylenediamine in the range of 2 wt% or more and 10 wt% or less with respect to the total of p-xylene and the lower alcohol is added to obtain a mixed solution.
Step S230: Incubate the mixed solution for a time of 5 minutes or more and 30 minutes or less.

Each step will be described in detail.
Since the fullerene is the same as the above-mentioned fullerene in step S210, the description thereof will be omitted. The obtained fullerene nanosheet has a hexagonal plate-like structure that is not porous, and has, for example, a diameter in the range of 1 μm or more and 4 μm or less, and a thickness in the range of 300 nm or more and 1 μm or less. .. Preferably, the diameter is in the range of 1 μm or more and 3 μm or less, and the thickness is in the range of 500 nm or more and 700 nm or less.

In step S210, p-xylene is a good solvent for fullerenes, so that fullerenes can be well dispersed.

In step S210, the lower alcohol is a poor solvent for fullerenes and can form a liquid-liquid interface with p-xylene. There is no particular limitation as long as the above-mentioned carbon number is satisfied, but at least one is preferably selected from the group consisting of methanol, ethanol, propanol, and isopropanol. These can form a liquid-liquid interface with p-xylene, and fullerene nanosheets can be obtained in good yield.

In step S210, a lower alcohol is preferably added to the fullerene dispersion. This promotes the formation of a liquid-liquid interface. Further, preferably, the lower alcohol is added while sonicating the fullerene dispersion. As a result, a high-quality liquid-liquid interface is formed, and the formation of fullerene nanosheets is promoted.

In step S210, the lower alcohol is preferably added in an amount of 2 times or more and 10 times or less by volume with respect to p-xylene. As a result, a liquid-liquid interface is formed, and the formation of fullerene nanosheets is promoted.

In step S210, the concentration of fullerene (mg / mL) in the fullerene dispersion is preferably in the range of 0.2 mg / mL or more and 0.6 mg / mL or less. Within this range, the formation of fullerene nanosheets is promoted.

The liquid-liquid interface precipitation method in step S210 may be performed in a temperature range of 15 ° C. or higher and lower than 200 ° C. If the temperature exceeds 200 ° C., the reaction may not proceed. It is preferably 15 ° C. or higher and 100 ° C. or lower, and more preferably 15 ° C. or higher and 50 ° C. or lower.

In step S220, addition of the above-mentioned predetermined amount of ethylenediamine causes amination between ethylenediamine and fullerene nanosheets.

In step S220, if the amount of ethylenediamine added is less than 2 wt%, amination may not proceed sufficiently. Even if the amount of ethylenediamine added exceeds 10 wt%, there is no change in the progress of amination, so the upper limit is preferably 10 wt%. More preferably, the amount of ethylenediamine added is in the range of 2 wt% or more and 6 wt% or less with respect to the total of p-xylene and the lower alcohol. Within this range, amination can proceed efficiently.

The inventors of the present application have found that by performing the incubation treatment in step S230, the fullerene nanosheets obtained in step S210 are selectively etched to become porous fullerene nanosheets.

Specifically, in step S230, the plate-like surface of the hexagonal plate-like structure of the fullerene nanosheet is selectively etched by incubating (holding) for 5 minutes or more and 30 minutes or more using ethylenediamine having a predetermined concentration. The hexagonal plate-like structure is maintained even after etching.

In step S230, the incubation may be performed while sonicating. This promotes etching.

Following the incubation, the product may be washed one or more times with a mixed solution of p-xylene, lower alcohol and ethylenediamine. This can further promote etching.

In this way, the fullerene nanosheets of the present invention can be obtained, but the product may be recovered by centrifuging after step S230, washing with a lower alcohol, and then drying the product.

(Embodiment 2)
In the second embodiment, the crystal oscillator gas sensor using the fullerene nanosheet of the present invention described in the first embodiment will be described.
FIG. 3A is a front view showing a crystal oscillator gas sensor using the fullerene nanosheet of the present invention.
FIG. 3B is a side view showing a crystal oscillator gas sensor using the fullerene nanosheet of the present invention.

The crystal oscillator (QCM) electrode 310 of the QCM gas sensor 300 according to the present invention is provided with the gas sensor film 320 containing the fullerene nanosheet described in the first embodiment.

Specifically, the QCM electrode 310 includes a crystal substrate 330, electrodes 340a and 340b formed on the front and back main surfaces thereof, and lead wires 350a and 350b connected to the electrodes 340a and 340b, respectively. The crystal substrate 330 is an AT-cut substrate having a substantially disk shape. The electrodes 340a and 340b are electrodes of gold, platinum, chromium, nickel and the like formed by physical vapor deposition or the like. The lead wires 350a and 350b may be connected to an AC power source or the like, apply a potential to the crystal substrate 330, and be connected to a frequency counter or the like capable of measuring a change in frequency. The gas sensor film 320 is applied on at least one of the electrodes 340a and 340b, but may be formed on both electrodes 340a and 340b.

The gas sensor film 320 may be in the form of a film containing the fullerene nanosheet 100. Such a film can be obtained by dispersing the fullerene nanosheet 100 in water or an organic solvent and applying the fullerene nanosheet 100 on the quartz substrate 330 on which the electrodes 340a and 340b are formed. The organic solvent is exemplified by ethanol, ethylene glycol and α-terpineol. The application is performed by coating, drop casting, spraying, dipping, spin coating, screen printing and the like. Preferably, heating is performed to remove the solvent after application. The gas sensor film 320 has a thickness in the range of 50 nm or more and 500 nm or less. This increases the sensor sensitivity. The gas sensor film 320 may be made of a fullerene nanosheet 100 alone, or may contain an organic binder resin, an organic solvent, or the like.

The operation of the QCM gas sensor 300 of the present invention will be described. An electric potential is applied to the crystal substrate 330 via the lead wires 350a and 350b of the QCM gas sensor 300 and the electrodes 340a and 340b. As a result, the crystal substrate 330 vibrates at a predetermined resonance frequency due to the thickness sliding vibration. Here, when an acid gas is passed through the QCM gas sensor 300, the acid in the gas is adsorbed on the fullerene nanosheet in the gas sensor film 320. As a result, energy loss corresponding to the mass of the adsorbed acid occurs, so that the predetermined resonance frequency changes. The frequency change is measured by a frequency counter or the like via the lead wires 350a and 350b. In this way, if the QCM gas sensor 300 of the present invention is used, the acid in the gas can be detected by changing the frequency.

In particular, the QCM gas sensor 300 of the present invention preferably detects an acid gas selected from the group consisting of formic acid, acetic acid and propionic acid with high accuracy.

The application of the QCM sensor has been described from the high selectivity of the fullerene nanosheet of the present invention to acid gas. However, since the fullerene nanosheet of the present invention has hydrophilicity, nano-sized or submicron-sized objects can be encapsulated and transported / released. It is also possible to apply it to bio-related applications.

Next, the present invention will be described in detail with reference to specific examples, but it should be noted that the present invention is not limited to these examples.

[Example 1]
In Example 1, an attempt was made to produce fullerene nanosheets according to the method shown in FIG.

Fullerene C ₆₀ powder (purity 99.5%, manufactured by MTR Ltd.) was dispersed in p-xylene (purity 98.0%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and sonicated for 1 hour to disperse the fullerene. The liquid was prepared. The fullerene concentration in the fullerene dispersion was 0.4 mg / mL. Fullerene nanosheets were formed by a liquid-liquid interfacial precipitation method using a fullerene dispersion (step S210 in FIG. 2).

Specifically, the fullerene dispersion (1 mL) was placed in a 13.5 mL washed glass bottle, placed in an ultrasonic bath and sonicated. Then, isopropanol (5 mL, purity 99.7%, manufactured by Nacalai Tesque, Inc.) was rapidly added to the fullerene dispersion (about 2 seconds). Sonication was performed for 1 minute, the glass bottle was removed from the ultrasonic bath and held at 25 ° C. for 5 minutes.

The field emission type indicates that some samples are centrifuged, the product is washed with isopropanol, and dried at 80 ° C. for 24 hours to form fullerene nanosheets (hereinafter sometimes referred to as FNS). Confirmation was performed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation), and the diameter distribution was examined. The results are shown in FIGS. 4 to 6.

Ethylenediamine (EDA, purity 99.0%, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the above fullerene dispersion to obtain a mixed solution (step S220 in FIG. 2). At this time, the concentration of ethylenediamine was 4 wt% with respect to the total of p-xylene and isopropanol.

After the addition, the mixed solution was incubated (step S230 in FIG. 2). Incubation (retention of the mixture) was performed at 25 ° C. for 10 minutes while sonicating.

The resulting mixture was brown. Finally, centrifugation was performed, the product was washed 3 times with isopropanol, dried at 80 ° C. for 24 hours, and then observed and evaluated. The sample used for evaluation may be referred to as FNS-EDA.

The sample was observed using a field emission scanning electron microscope and a field emission transmission electron microscope (TEM, manufactured by JEOL Ltd., JEM-2100F). The sample was evaluated using an X-ray diffractometer (XRD, manufactured by Rigaku Co., Ltd., RINT-Ultima III). The surface functional groups of the sample were identified using a total reflection Fourier transform infrared spectrophotometer (ATR-FTIR, Thermo Fisher Scientific Co., Ltd., Nexus 670).

The Raman spectrum of the sample was measured using a triple laser Raman spectroscopic measuring device (T64000, manufactured by Jobin Yvon). A laser with a wavelength of 514.5 nm and a 0.01 mW output was used for the measurement.

The X-ray photoelectron spectrum of the sample was measured using a thetaprobe spectrometer (manufactured by Thermoelectron). An Al—Kα monochromatic line (energy 15 keV) was used for the measurement. C1s (energy peak position of C 1s orbital), O1s (energy peak position of O 1s orbital) and N1s (energy peak position of N 1s orbital) of core level XPS were recorded in 0.05 eV steps. A built-in electroflood gun was used for the measurement to avoid the accumulation of charge on the sample. The UV-vis spectrum of the sample was measured using a spectrophotometer (V-670, manufactured by JASCO Corporation). The mass spectrometric spectrum of the sample was measured using a mass spectrometer (MALDI-TOF-MS, manufactured by Shimadzu Corporation, H17S00282).

The gas sensor capability of the obtained sample was investigated using a quartz crystal microbalance (QCM). Using a resonance frequency of 9 MHz (AT-cut), the frequency change during adsorption / desorption of guest gas was recorded for the Au resonator (QCM electrode) coated with each sample. The QCM electrode was adjusted as follows. The sample (0.5 mg) was dispersed in isopropanol (1 mL) and stirred for 30 seconds. A fixed amount (2 μL) of the obtained suspension was drop cast onto a QCM electrode and dried in vacuum for 12 hours at 80 ° C.

When the frequency change reached equilibrium, the QCM electrode was exposed to air to desorb the adsorbed gas. For the reproducibility test of the QCM electrode, the time dependence of the frequency shift (Δf) during repeated gas exposure and desorption was recorded. The above results are shown in FIGS. 7 to 18.

FIG. 4 is a diagram showing an SEM image of the fullerene nanosheet obtained by step S210 of FIG.
FIG. 5 is a diagram showing the diameter distribution of fullerene nanosheets.
FIG. 6 is a diagram showing a STEM image of fullerene nanosheets.

According to FIG. 4, it can be seen that the sheet (fullerene nanosheet) is made of fullerene having uniform crystallinity. The sheet had a hexagonal plate-like structure and had a smooth surface. A histogram of the diameters of 100 randomly selected sheets from the SEM image is shown in FIG. According to FIG. 5, the diameter of the sheet was in the range of 1 μm or more and 3 μm or less. The average thickness was 600 nm. Further, according to FIG. 6, it was found that the fullerene nanosheet was not porous.

FIG. 7 is a diagram showing an SEM image of the sample of Example 1.
FIG. 8 is a diagram showing a STEM image of the sample of Example 1.
FIG. 9 is a diagram showing the diameter distribution of the sample of Example 1.
FIG. 10 is a diagram showing a TEM image and an HRTEM image of the sample of Example 1.

According to FIGS. 7 and 8, the sample of Example 1 was porous with a large number of pores, and its shape had a hexagonal plate-like structure. The sample of Example 1 had two types of porosity, a macro channel and a micro channel. Comparing the surface of the sample of Example 1 with that of the fullerene nanosheet (FIG. 4), the surface of the sample of Example 1 was rougher than that of the fullerene nanosheet.

A histogram of the diameters of 100 randomly selected sheets from the SEM image is shown in FIG. According to FIG. 9, the diameter of the sample of Example 1 was in the range of 1 μm or more and 2 μm or less, and the average thickness was 500 nm. From these, it is suggested that the sample of Example 1 maintained the size of the fullerene nanosheet before etching even after etching by step S230 in FIG. 2, and the plate-like surface of the fullerene nanosheet was selectively etched.

FIG. 10 shows a TEM image (A) and an HR-TEM image (B) of the sample of Example 1. According to FIG. 10B, it was found that the sample of Example 1 showed lattice fringes derived from fullerene _C60 and had crystallinity even after etching.

FIG. 11 is a diagram showing an XRD pattern of the sample of Example 1.

In FIG. 11, in addition to the XRD pattern of the sample (FNS-EDA) of Example 1, the XRD pattern (FNS) of the fullerene nanosheet before etching is also shown. C ₆₀ is known to have a face-centered cubic lattice (fcc) structure with a lattice constant a = 1.4206 nm and a lattice volume V = 2.867 nm ³ , but the FNS in FIG. 11 is similar to C ₆₀ . Shows diffraction peaks corresponding to the (111), (022), (113), (222), (133), and (024) planes of the face-centered cubic lattice structure (fcc), and the lattice constant a = 1.4177 nm. , Lattice volume V = 2.849 nm ³ .

It was found that the XRD pattern of the sample of Example 1 in FIG. 11 was similar to that of FNS, was indexed to the face-centered cubic lattice structure (fcc), and did not change after etching. The sample of Example 1 had a lattice constant a = 1.4192 nm and a lattice volume V = 2.858 nm ³ .

FIG. 12 is a diagram showing a Raman spectrum of the sample of Example 1.

In FIG. 12, in addition to the Raman spectrum of the sample (FNS-EDA) of Example 1, the Raman spectrum (FNS) of the fullerene nanosheet before etching is also shown. According to FIG. 12, the Raman spectrum of the sample of Example 1 was the same as that of FNS. The pentagonal pinch mode Ag ₍ 2) mode located at 1464 cm ^-1 , which is active against the intermolecular bond of C60, did not shift even after etching with ethylenediamine in step S230. This indicates that C ₆₀ is mainly used in the sample of Example 1 after etching.

FIG. 13 is a diagram showing an FTIR spectrum on the high frequency side of the sample of Example 1.
FIG. 14 is a diagram showing an FTIR spectrum on the low frequency side of the sample of Example 1.

13 and 14 show, in addition to the FTIR spectrum of the sample (FNS-EDA) of Example 1, the FTIR spectrum of the fullerene nanosheet (FNS) before etching. Both FTIRF spectra peaked at 525 cm ^-1 , 575 cm ^-1 , 1181 cm ^-1 and 1427 cm ^-1 , which are characteristic of fullerene C ₆₀ .

In addition, all FTIR spectra showed a small peak at 3018 cm ^-1 to 2900 cm ^-1 . These peaks are due to CH stretching vibrations corresponding to solvent molecules. However, the FTIR spectrum of the sample of Example 1 showed a broad band at 3315 cm ^-1 due to the NH stretching vibration, but not that of FNS. This indicates that the seeds related to ethylenediamine are present on the surface of the sample of Example 1.

FIG. 15 is a diagram showing a UV-vis spectrum of the sample of Example 1.

In FIG. 15, in addition to the UV-vis spectrum of the sample (FNS-EDA) of Example 1, the UV-vis spectrum of the fullerene nanosheet (FNS) before etching is also shown. According to FIG. 15, the intensity of the electron absorption band of the sample of Example 1 was significantly reduced as compared with that of FNS. This is because the color of the sample solution of Example 1 was tan, and the sample of Example 1 contained nitrogen atoms showing vibration and electron interaction of Herzberg-Teller, and electron transitions occurred. Suggests that has decayed.

FIG. 16 is a diagram showing the XPS spectrum of the sample of Example 1.

In FIG. 16, in addition to the XPS spectrum of the sample ₍ FNS-EDA) of Example 1, the XPS spectra of C60 and the fullerene nanosheet (FNS) before etching are also shown. According to FIG. 16, the XPS spectra of C60 and FNS used as raw materials showed core level peaks of C1s and _O1s . Oxygen is due to air oxidation. On the other hand, the XPS spectrum of the sample of Example 1 showed a core level peak of N1s at 400 eV in addition to the core level peak of C1s and O1s. From these, it was shown that the fullerene nanosheet containing a nitrogen atom can be obtained by carrying out the production process of FIG.

Furthermore, when the content of nitrogen atoms was calculated from the XPS spectrum of Example 1, it contained 6.1 atomic% of nitrogen atoms. It was found that the fullerene nanosheets of the present invention contained nitrogen atoms in the range of 5 atomic% or more and 7 atomic% or less.

FIG. 17 is a diagram showing XPS spectra at the N1s core level of the sample of Example 1.

FIG. 17 shows the N1s peak in which the convolution of the sample (FNS-EDA) of the sample 1 was unconvolved, and it was found that the oxidized nitrogen atom was present in the sample of the example 1. Although not shown, when the mass spectrum of the sample of Example 1 was measured, it was found that the sample of Example 1 was mainly composed of fullerene _C60 and the surface was amination.

From these, it was found that by performing the production process of FIG. 2, fullerene and ethylenediamine reacted, and the sample of Example 1 had an aminized surface.

The contact angles of the sample of Example 1 (FNS-EDA) and the fullerene nanosheet (FNS) before etching were examined. As a result, FNS showed high water repellency of more than 140 °, while the sample of Example 1 showed high hydrophilicity of 40 °.

As described above, it has been found that the manufacturing process of FIG. 2 can obtain a porous fullerene nanosheet having a hexagonal plate-like structure containing fullerene containing a nitrogen atom as a main component.

Next, a QCM sensor using the sample of Example 1, which is a porous fullerene nanosheet containing a nitrogen atom and having hydrophilicity, will be described. Hereinafter, the QCM sensor using the sample of Example 1 will be referred to as the QCM sensor of Example 1.

FIG. 18 is a diagram showing QCM frequency shifts for various volatile organic compounds by the QCM sensor of Example 1.

According to FIG. 18, the QCM sensor of Example 1 showed a frequency shift response to formic acid, acetic acid, propionic acid, phenol, formaldehyde, water and the like. Among them, the fullerene nanosheets of the present invention showed a larger frequency shift with respect to the adsorption of acid gases such as formic acid, acetic acid and propionic acid. Although not shown, it was confirmed that the QCM sensor of Example 1 has excellent reproducibility.

Since the fullerene nanosheet of the present invention has hydrophilicity, it is applied to bio-related applications. Since the fullerene nanosheet of the present invention has selective reactivity with a specific acid gas, it is applied to a crystal oscillator gas sensor.

100 Fullerene Nanosheet 110 Mesopore 300 Quartz Crystal Microbalance (QCM) Gas Sensor 310 Quartz Crystal Microbalance (QCM) Electrode 320 Gas Sensor Film 330 Quartz Crystal Substrate 340a, 340b Electrode 350a, 350b Lead Wire

Claims (19)

It is a fullerene nanosheet whose main component is fullerene.
It has a hexagonal plate-like structure and has a hexagonal plate-like structure.
Porous and
The fullerene is a fullerene nanosheet containing a nitrogen atom. The fullerene is selected from at least one group consisting of C ₆₀ fullerene, C ₇₀ fullerene, C ₇₆ fullerene, C ₇₈ fullerene, C ₈₂ fullerene, C ₈₄ fullerene, C ₉₀ fullerene, C ₉₄ fullerene, and derivatives thereof. The fullerene nanosheet according to claim 1. The fullerene nanosheet according to claim 2, wherein the fullerene is _C60 fullerene and / or a derivative thereof. The fullerene nanosheet according to claim 3, which has a face-centered cubic lattice structure (fcc). The fullerene nanosheet according to any one of claims 1 to 4, which has hydrophilicity. The diameter of the hexagonal plate-like structure is in the range of 1 μm or more and 4 μm or less.
The fullerene nanosheet according to any one of claims 1 to 5, wherein the thickness of the hexagonal plate-like structure is in the range of 300 nm or more and 1 μm or less. The fullerene nanosheet according to any one of claims 1 to 6, which has a peak due to NH expansion and contraction vibration in a range of 3000 cm ^-1 or more and 3450 cm ^-1 or less in an FTIR spectrum measured by a Fourier transform infrared spectroscopic altimeter. The fullerene nanosheet according to any one of claims 1 to 7, which has an N1s peak of nitrogen in the range where the binding energy is 398.5 eV or more and 400.5 eV or less in the XPS spectrum measured by X-ray photoelectron spectroscopy. The fullerene nanosheet according to any one of claims 1 to 8, wherein the nitrogen atom is contained in the range of 4 atomic% or more and 10 atomic% or less. The fullerene nanosheet according to any one of claims 1 to 9, wherein the nitrogen atom is oxidized. The fullerene nanosheet according to any one of claims 1 to 10, wherein the surface of the fullerene nanosheet is amination. A fullerene nanosheet is formed by mixing a fullerene dispersion in which fullerene is dispersed in p-xylene and a lower alcohol having 5 or less carbon atoms by a liquid-liquid interfacial precipitation method.
Ethylenediamine in the range of 2 wt% or more and 10 wt% or less with respect to the total of the p-xylene and the lower alcohol was added to obtain a mixed solution.
The method for producing a fullerene nanosheet according to any one of claims 1 to 11, which comprises incubating the mixed solution for a time of 5 minutes or more and 30 minutes or less. 12. The method of claim 12, further comprising washing the product with the mixed solution of p-xylene, lower alcohol and ethylenediamine following the incubation. The method according to any one of claims 12 or 13, wherein the lower alcohol is selected from the group consisting of methanol, ethanol, propanol, and isopropanol. The method according to any one of claims 12 to 14, wherein the fullerene nanosheet is formed while performing ultrasonic treatment. The method according to any one of claims 12 to 15, wherein the mixed solution is obtained while performing ultrasonic treatment. The method according to any one of claims 12 to 16, wherein the fullerene is _C60 fullerene and / or a derivative thereof. A crystal oscillator gas sensor equipped with a gas sensor membrane.
The gas sensor membrane is a crystal oscillator gas sensor containing the fullerene nanosheet according to any one of claims 1 to 11. The crystal oscillator gas sensor according to claim 18, which detects an acid gas selected from the group consisting of formic acid, acetic acid and propionic acid.

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