CN114804080A - Method for preparing graphene film in low cost and large area - Google Patents
Method for preparing graphene film in low cost and large area Download PDFInfo
- Publication number
- CN114804080A CN114804080A CN202210391231.4A CN202210391231A CN114804080A CN 114804080 A CN114804080 A CN 114804080A CN 202210391231 A CN202210391231 A CN 202210391231A CN 114804080 A CN114804080 A CN 114804080A
- Authority
- CN
- China
- Prior art keywords
- graphene oxide
- reduction
- oxide films
- films
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 186
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 178
- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000010410 layer Substances 0.000 claims abstract description 54
- 230000009467 reduction Effects 0.000 claims abstract description 49
- 239000002356 single layer Substances 0.000 claims abstract description 28
- 238000009413 insulation Methods 0.000 claims abstract description 7
- 239000010408 film Substances 0.000 claims description 81
- 239000010409 thin film Substances 0.000 claims description 21
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 238000006722 reduction reaction Methods 0.000 abstract description 46
- 238000011946 reduction process Methods 0.000 abstract description 16
- 238000006243 chemical reaction Methods 0.000 abstract description 7
- 230000008569 process Effects 0.000 abstract description 6
- 238000007540 photo-reduction reaction Methods 0.000 abstract description 3
- 230000001960 triggered effect Effects 0.000 abstract description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000003990 capacitor Substances 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 5
- 238000001228 spectrum Methods 0.000 description 5
- 239000007772 electrode material Substances 0.000 description 4
- 238000004146 energy storage Methods 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- 238000001069 Raman spectroscopy Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000003775 Density Functional Theory Methods 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 230000002269 spontaneous effect Effects 0.000 description 2
- 238000004627 transmission electron microscopy Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006392 deoxygenation reaction Methods 0.000 description 1
- 238000001938 differential scanning calorimetry curve Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000024 high-resolution transmission electron micrograph Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/184—Preparation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/04—Specific amount of layers or specific thickness
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/20—Graphene characterized by its properties
- C01B2204/32—Size or surface area
Abstract
The invention provides a method for preparing a graphene film with low cost and large area, which comprises the steps of firstly, stacking single-layer graphene oxide films, utilizing energy transfer generated by the graphene oxide films in the photo-reduction process to initiate reduction of adjacent graphene oxide films so as to initiate self-triggered chain reduction of graphene oxide, and simultaneously carrying out heat insulation treatment on the stacked graphene oxide films, fully preserving heat released in the reaction and ensuring the continuous reaction. According to the invention, the heat generated in the photo-thermal reduction process is managed, and the heat is utilized to realize large-scale reduction of the independent graphene oxide film. Without further energy input, the stack of multilayer graphene oxide films (e.g., 25 layers) can be rapidly deoxygenated from the self-sustaining chain reduction process. The resulting reduced graphene oxide film showed higher quality in terms of conductivity and porosity.
Description
Technical Field
The invention belongs to the technical field of porous graphene film preparation, and particularly relates to a method for preparing a graphene film with low cost and large area.
Background
Supercapacitors (also called "double layer capacitors") are electrochemical capacitors with much higher capacitance values than other capacitors. Supercapacitors are widely used for energy storage and energy supply due to their high energy density, fast charge/discharge capability, long life over one million charge cycles and ability to operate over a wide temperature range of-40 ℃ to 70 ℃.
A typical supercapacitor includes two electrodes separated by an ion-permeable membrane ("separator layer"), and a pair of current collectors connected to the electrodes, respectively.
The activated carbon is conventional superThe most widely used electrode materials in capacitors. Although activated carbon theoretically provides a large specific surface area to accommodate a large number of ions, most of the pores are not interconnected and the ions cannot effectively utilize their surface area, resulting in a low specific capacitance and a maximum energy density of about 5 to 7Wh kg -1 . Therefore, in order to further increase the specific capacitance and energy density of the supercapacitor, it is necessary to develop an electrode material having a large specific surface area and high conductivity.
The pure graphene material has 2630m 2 (g) an extra large theoretical specific surface area and excellent electrical conductivity>1000S/m). More importantly, as a two-dimensional layered material, the pores inside the material are all interconnected, so that ions can be fully attached to the surface of the material. Thus, graphene has been considered as the most promising electrode material for high-performance supercapacitors. In the past decade, graphene and its derivatives have been widely developed as supercapacitor electrode materials to replace activated carbon. There have been some studies to achieve high performance graphene supercapacitors.
The application of the super capacitor has to produce the porous graphene film on a large scale. Therefore, several methods have been used to manufacture porous graphene thin films on a large scale. The oxidation-reduction method can be used for producing the graphene porous material in a large quantity at low cost. However, this approach has shown relatively low conductivity and a large number of material defects, which limit the performance of the fabricated supercapacitor. Accordingly, what is needed is a solution or improvement to one or more of the disadvantages or limitations associated with the prior art, or at least to provide a useful alternative.
Chemical or thermal reduction of graphene oxide requires hazardous chemicals or high temperatures. In recent years, photoreduction strategies, including photothermal and photochemical reduction, have become attractive processes for the rapid production of high quality graphene. In particular, reduction of graphene oxide by a simple flash lamp is a clever approach, as it is green, efficient and low cost. The energy from the flash lamp will cause intense heating of the graphene oxide and instant deoxygenation of the graphene oxide within a few milliseconds. Rapid degassing during reduction, including water vapor, carbon monoxide and carbon dioxide, can create micropores, cracks and voids in the reduced graphene oxide, which is particularly advantageous for their applications in energy storage and catalysis. Despite the advantages, the productivity of flash lamp reduction is limited by the depth of light penetration, the exposure area, and the form and microstructure of the graphene oxide precursor, due to the limited power output of the flash lamp. Normally, only a certain thickness of graphene oxide film can be properly reduced, and for a graphene oxide film with a larger thickness, the power of a flash lamp needs to be correspondingly increased, but if the control is not proper, the too high power of the flash lamp easily causes violent explosion, which greatly limits the application of the method. Controlling the power of the flash lamp and increasing its reduction efficiency is an urgent solution to expand its application range and bring about more economical and green production techniques.
Disclosure of Invention
The invention aims to provide a method for preparing a graphene film with low cost and large area, which can realize large-scale preparation of the graphene film without additional energy input by managing heat generated in a photo-thermal reduction process.
The invention provides a method for preparing a graphene film with low cost and large area, which comprises the following steps:
the method comprises the steps of stacking a plurality of single-layer graphene oxide films, carrying out heat insulation treatment, reducing the single-layer graphene oxide films by using a flash lamp, and carrying out self-sustaining chain reduction on the single-layer graphene oxide films through thermal management.
Preferably, the thickness of the single-layer graphene oxide thin film is 1 to 100 μm, more preferably 5 to 90 μm, such as 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, and preferably ranges with any of the above values as an upper limit or a lower limit.
Preferably, the number of stacked layers of the single-layer graphene oxide thin film is 2 to 100, more preferably 10 to 90, such as 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, and preferably any of the above values is an upper limit or a lower limit.
Preferably, the power of the flash lamp is 2.5-640 Ws, more preferably 10-600 Ws, such as 2.5Ws, 5Ws, 10Ws, 50Ws, 100Ws, 150Ws, 200Ws, 250Ws, 300Ws, 350Ws, 400Ws, 450Ws, 500Ws, 550Ws, 600Ws, preferably any of the above values as upper or lower limit.
Preferably, the material of the heat insulation container is paper and/or metal.
Preferably, the metal is aluminum.
Preferably, a plurality of single-layer graphene oxide films are stacked, the top of each single-layer graphene oxide film does not completely cover the paper, and then a flash lamp is placed on the top of the paper for reduction;
or, a plurality of single-layer graphene oxide films are stacked and placed in a container with an open top and a metal reflective layer inside, and then a flash lamp is placed on the top of the container for reduction.
The invention provides a method for preparing a graphene film with low cost and large area, which comprises the following steps: the method comprises the steps of stacking a plurality of single-layer graphene oxide films, carrying out heat insulation treatment, reducing the single-layer graphene oxide films by using a flash lamp, and carrying out self-sustaining chain reduction on the single-layer graphene oxide films through thermal management. According to the method, the single-layer graphene oxide films are stacked, energy generated by the graphene oxide films is transferred in the photoreduction process to initiate reduction of the adjacent graphene oxide films, so that self-triggered chain reduction of the graphene oxide is initiated, and meanwhile, the stacked graphene oxide films are subjected to heat insulation treatment, so that heat released in the reaction is fully stored, and the continuous reaction is ensured. According to the invention, the heat generated in the photo-thermal reduction process is managed, and the heat is utilized to realize large-scale reduction of the independent graphene oxide film. Without further energy input, the stack of multilayer graphene oxide films (e.g., 25 layers) can be rapidly deoxygenated from the self-sustaining chain reduction process. The resulting reduced graphene oxide films exhibit a high quality in terms of conductivity and porosity, which is desirable for their applications in catalysis and energy storage. The use of the manufactured electrodes demonstrates their application as supercapacitor electrodes with high specific capacitance and energy density.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a flow chart of a method for manufacturing a graphene electrode and a super capacitor by a flash lamp chain reduction method;
fig. 2 is an illustration of a setup of a flash-triggered self-reduction process showing the reduction of 5 graphene oxide layers for demonstration, the time scale being based on experimental observations;
FIG. 3 is a still frame image of the chain reduction process (25 individual graphene oxide films, each film having a thickness of 20 μm), with elapsed time recorded in milliseconds;
fig. 4(a) is a photograph from self-reduced graphene oxide thin films obtained from stacked layers 1 st, 5 th, 10 th, 15 th and 25 th, from left to right; (b) TEM and (c) HRTEM images of a typical reduced graphene oxide thin film; (d) SEM images of typical reduced graphene oxide films; (e) and (f): raman and XPS results of reduced graphene oxide films of different layers;
FIG. 5 is a DFT calculation for graphene oxide reduction; (a) graphene oxide of θ 1/18; (b) graphene; (c) graphene oxide of θ 1/18; carbon and oxygen are shown as gray and red spheres, and the graphene oxide reduced Δ E and Δ G (a → b and c → b) have been listed in units of eV;
figure 6(a) shows a Fourier Transform Infrared (FTIR) spectrum of graphene oxide stored in nitrogen, in air, heated at 120 ℃ for 5 hours, and reduced graphene oxide after flash lamp reduction; (b) TGA results before and after drying of the graphene oxide sample in a nitrogen atmosphere;
FIG. 7 shows two reduction modes for realizing multiple reduction; (a) the top layer covered a sheet of paper, but the edges of the lower layer were exposed to a flash lamp; (b) all layers were wrapped with aluminum foil, only the first layer was exposed to the flash lamp;
FIG. 8 is an XRD spectrum of the free-standing graphene oxide film before flash reduction;
fig. 9 is a BET nitrogen (77K) adsorption isotherm of flash lamp reduced graphene oxide of the first and second layers; BET surface areas of 198 and 178m, respectively 2 g -1 ；
Fig. 10 is XPS results of flash reduced graphene oxide films; (a) wide scanning; (b) a C1s spectrum of the flashed reduced graphene oxide from the first layer; (c) a C1s spectrum of flash reduced graphene oxide from layer 5;
fig. 11 is a BET nitrogen (77K) adsorption isotherm of flash reduced graphene oxide having a size of 8 x 12cm x cm; BET surface area of 220m 2 g -1 ；
FIG. 12 is a schematic of heat flow and heat loss with and without (a) thermal management; (c) a DSC curve of the graphene oxide film under a nitrogen atmosphere; (d) the temperature detected by a laser thermal infrared imager; (e) calculating DFT of reduction of the graphene oxide; (1) graphene oxide of θ 1/18; (2) graphene; (3) 1/18 graphene oxide; carbon and oxygen are shown as gray and red spheres; Δ E and Δ G (1 to 2 and 3 to 2) for graphene oxide reduction have been listed in units of eV;
figure 13 is BET nitrogen (77K) adsorption isotherm of flash reduced graphene oxide with a size of 2 x 3 cm; BET area of 258m 2 g -1 ；
FIG. 14 is the electrochemical performance of reduced graphene oxide thin films from self-reduced layer 1 and layer 25; an EIS curve (a), a CV curve (b), and a charge-discharge curve (c).
Detailed Description
The invention provides a method for preparing a graphene film with low cost and large area, which comprises the following steps:
the method comprises the steps of stacking a plurality of single-layer graphene oxide films, carrying out heat insulation treatment, reducing the single-layer graphene oxide films by using a flash lamp, and carrying out self-sustaining chain reduction on the single-layer graphene oxide films through thermal management.
An overall flow chart for manufacturing a graphene electrode and a supercapacitor by a flash lamp chain reduction method is shown in fig. 1. As shown in fig. 2, in order to achieve chain reduction, the multilayer freestanding graphene oxide thin film needs to be orderly stacked. Due to the low cross-sectional thermal conductivity of graphene oxide and the air gaps introduced between the graphene oxide films, the multi-layer stacked configuration can effectively inhibit parasitic heat dissipation during the reduction process. Once the top layer is exposed to the flash lamp and reduced, the other layers are also quickly and completely reduced. In the present invention, the "top layer" refers to the graphene oxide layer exposed to the flash lamp, and the "top layer" may be in any direction according to the structure and position of the actual device.
The reduction process was recorded by a high speed video camera as shown in fig. 3, where the entire reduction process for 25 layers of 20 μm thick graphene oxide film took only 208 ms. The mass and area of the 25-layer film were 0.75g and 0.06m, respectively 2 Converted to 3.6 g.s -1 And 0.3m 2 ·s -1 The production speed of the method can meet the requirement of large-scale industrial production. At the same time, the energy cost of this process is only one flash pulse, which is much more economical than other reduction methods.
A photograph of the reduced graphene oxide thin film after the self-reduction process is shown in fig. 4 a. Compared with the graphene oxide precursor, the reduced graphene oxide film has half weight reduction, but shows a complete film without breakage, and no obvious difference is observed among films of different layers. The microstructure of the reduced graphene oxide thin film was examined by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) (fig. 4 b-d). As shown in fig. 4b and c, the product showed a typical two-dimensional sheet structure with a lattice distance of 0.33nm, consistent with the values reported for graphene. From the SEM image (FIG. 4d), we can observe that the reduced graphene oxide thin film is reducedBecomes very porous. For the graphene oxide precursor, it shows a peak at 2 θ (9.12 °) in the XRD pattern (fig. 8), corresponding to a distance between stacked graphene oxide sheets of
Consistent with the apparent thickness of the graphene oxide monolayer. After the flash lamp reduction, the oxidized graphene peak disappears, and a reduced oxidized graphene film has a broad peak with 22.5 degrees as the center. X-ray photoelectron spectroscopy (XPS) was used to further quantify the degree of reduction. XPS spectra of reduced graphene oxide thin films from different layers are given in fig. 4e and 6. Table 1 summarizes the proportions of the different ingredients. The removal of oxygen content after flash lamp reduction is evident, and the C-O peak is significantly reduced, which means the recovery of pure C-C bonds. It can be concluded that chain reduction can produce reduced graphene oxide films of high and consistent quality.
TABLE 1
| C-C | C-O | C＝O | O＝C＝OH | C-N | |
| Graphene oxide-air | 50.41 | 41.3 | 3.13 | 5.16 | |
| Graphene oxide-N 2 | 47.16 | 45.8 | 3.17 | 3.97 | |
| FR graphene oxide-1-25 | 61.23 | 23.44 | 6.85 | 8.48 | |
| FR graphene oxide-5-25 | 59.63 | 23.69 | 9.14 | 7.53 | |
| FR graphene oxide-25 | 57.53 | 24.81 | 5.59 | 1.61 | 10.57 |
| C | O | N | C/O | ||
| Graphene oxide-air | 67.46 | 32.54 | NA | 2.07 | |
| Graphene oxide-N 2 | 65.19 | 33.82 | 0.98 | 1.92 | |
| FR graphene oxide-1-25 | 91.8 | 8.2 | NA | 11.1 | |
| FR graphene oxide-5-25 | 90.58 | 8.80 | 0.62 | 10.2 | |
| FR graphene oxide-25 | 87.64 | 9.61 | 2.75 | 9.1 |
In table 1, "graphene oxide-air" represents graphene oxide stored in the air; "graphene oxide-N 2 "represents graphene oxide stored in nitrogen; "FR" in "FR graphene oxide-1-25" represents flash lamp reduction, FR graphene oxide-1-25 "represents the 1 st layer of flash lamp reduced 25-layer graphene oxide," FR graphene oxide-5-25 "represents the 5 th layer of flash lamp reduced 25-layer graphene oxide, and so on.
Raman spectroscopy is an effective tool for probing the microstructure of graphene-based materials. As shown in FIG. 4f, a typical Raman peak of reduced graphene oxide occurs at 1348cm wavelength D -1 And the G wave band is 1583cm -1 And 2D band 2450cm -1 . For reduced graphene oxide samples from different layers, they show very close D/G strengths, e.g., I for layers 1, 5 and 25 of reduced graphene oxide D /I G The ratio is 0.908. 0.901 and 0.909 respectively. We further analyzed the surface area of the flash-reduced graphene oxide thin films by measuring nitrogen gas absorption using Brunaur-Emmett-teller (bet) analysis method (fig. 7 and 8). The surface area of a graphene oxide thin film having a thickness of 20 μm was measured to be 10m before flashing 2 (ii) in terms of/g. After flash reduction, the surface areas of the reduced graphene oxide films of layer 1 and layer 25 were 178m, respectively 2 G and 175m 2 And the volume/g shows that the reduced graphene oxide thin film obtained by the self-reduction process has consistent quality.
Another advantage of this strategy is that the thickness of the graphene oxide film can be very wideRanging from 1 to 100 μm or more. This further highlights the importance of such a multi-layer configuration. Typically, a single layer graphene oxide film must be thinner than 10 μm to be properly reduced by a flash lamp. However, when the multilayer graphene oxide film (>5 layers), even thick films can be completely reduced. We successfully reduced graphene oxide films with thicknesses of 50 and 100 μm, both of which were fully reduced and maintained the integrity of the films. We also sought to prepare very dense graphene oxide films (thickness 50 μm, density 1250 mg/cm) 3 ) And such films can be fully reduced by similar strategies. The surface area of the 50 μm film after reduction was 108m 2 In terms of/g (FIG. 9). Graphene oxide films of different sizes (thickness 20 μm) were also investigated, with dimensions of 8 x 12 and 2 x 3(cm, width x length) being tried respectively. For large area (8 x 12) (cm, width x length) reduced graphene oxide films, the surface area was 220m 2 In terms of/g (FIG. 10). For small area (2 x 3) (cm, width x length) reduced graphene oxide films, the surface area was 258m 2 In terms of/g (FIG. 11). This indicates that the microstructure of the reduced graphene oxide film can be flexibly adjusted simply by changing the size of the graphene oxide film.
A mechanism for this rapid self-reduction process is proposed. Fig. 12(a) and (b) illustrate heat flow and energy loss with and without proper thermal management. In the photothermal reduction process, light is utilized by the absorber and converted into heat energy. The energy input of the flash illumination may be expressed as
E flash ＝AαQ flash (1)
A is the surface area facing the flash lamp, and depends mainly on the size of the graphene oxide film. α is absorption. Q flash Is the power density of the flash illumination. Energy input initiates reduction of the graphene oxide film and generates a large amount of heat during the exothermic reduction of the graphene oxide (E) exo ). Taking into account the energy (E) required for the reduction red ) And energy losses (e.g., radiation, conduction, and convection), the heat transferred from the upper layer for the 2 nd layer of graphene oxide film (the unexposed layer) can be expressed as:
ΔE 2 ＝E flash -E red +E exo -E loss (2)
due to the high absorption of graphene oxide films, E flash Is completely absorbed by the top layer, thus for the second layer E flash Should be about 0. Therefore, the net energy input to the reduction process depends primarily on the term (E) exo -E red ) It describes the difference between the energy produced in the exothermic process and the energy consumed in the reduction process. By DSC measurement (FIG. 12c), we found E exo Is about E red 10 times of, thus (E) exo -E red ) Will always be positive and energy can be fed to the underlying layer for reduction. It is assumed that the thickness and size of all graphene oxide thin films are uniform. For the graphene oxide film of the nth layer, the heat transferred from the other layers can be simplified as follows:
ΔE n ＝(n-1)(E exo -E red )-E loss (3)
where n is the number of layers. Based on this model, when E loss When properly managed, the energy generated will be proportional to the number of graphene oxide films present. Therefore, a large amount of graphene oxide thin films can be self-reduced without consuming external energy. To verify this, the temperature during the reaction was recorded by an infrared laser thermometer, and the relationship between time and temperature for different layers of graphene oxide films is shown in fig. 12 d. By increasing the number of layers, not only is the peak temperature higher (from 550 ℃ for a single layer to 650 ℃ for 25 layers), but the high temperature can be maintained for a longer time (over 2400 milliseconds from 600ms 25 for a single layer).
To understand the energetics associated with graphene oxide reduction, theoretical calculations were used to examine the reaction energy of graphene oxide to form oxygen. We started with a (3 × 3) graphene super cell, adsorbing a single oxygen through a C — O — C bond, as shown in fig. 12e (1), where the oxygen coverage is θ ═ 1/18. This graphene oxide was reduced to graphene (see fig. 12e (2), 1/2O was released by graphene oxide 2 (θ＝1/18)G+1/2O 2 . The calculated reaction energies Δ E and free energy changes Δ G were-1.08 eV and-1.40 eV at room temperature, which is clearThe exothermic and spontaneous nature of this reduction is demonstrated. We further increased the oxygen coverage to 1/9 by loading two oxygen atoms, as shown in fig. 12e (3), which are in graphene oxide (θ ═ 1/9) G + O 2 Δ E and Δ G are-2.39 eV and-3.03 eV, respectively, the exothermic and spontaneous properties do not change, but more energy is released, consistent with our observations, high oxygen coverage is crucial for vigorous reduction. It is noteworthy that treating the graphene oxide film in a nitrogen atmosphere not only eliminates the energy required for water evaporation, but also improves the coverage of oxygen-containing functional groups (OCFGs), which can be confirmed by comparing XPS results to place the graphene oxide film in air and nitrogen (fig. 13).
As shown by the above results, the reduced graphene oxide produced by our strategy exhibits abundant porosity while maintaining the integrity of the thin film structure. This unique structure is very advantageous for use as a stand-alone electrode for energy storage or catalytic applications, which would significantly simplify the device fabrication process. To demonstrate their potential applications, we directly used free-standing reduced graphene oxide films as electrodes for sandwich-type symmetric supercapacitors. The electrochemical properties of the reduced graphene oxide electrode were studied and the performance of the reduced graphene oxide thin films of different layers were compared to further confirm the scalability of our strategy. Using ionic liquids EMIMBF 4 (1M in acetonitrile) as electrolyte, all supercapacitors were charged to 3V. As shown in fig. 14a-c, layers 1 and 25 of the reduced graphene oxide films exhibited similar charge resistances, and specific capacitances calculated from CV spectra were 158 and 150F/g, respectively. The energy density calculated from the CC results was 38.6Wh kg -1 . Flash lamp reduction is more advantageous than other thermal reduction methods in terms of large-scale scalability and lower cost.
The present patent successfully demonstrates that large graphene oxide films can be deoxygenated without adjusting their size, thickness, and microstructure even with low energy power supplies such as camera flashes, through proper thermal management of the reduction system. Can be successfully reduced to have high density (1250 mg/cm) by one flash 3 ) The multilayer thick film of (2). Furthermore, can be replaced byThe size and thickness of the graphene oxide film are changed to fine-tune the microstructure of the reduced graphene oxide film. This work demonstrates the scalability of camera flashes, and advances in such low cost and green technology will further push the commercialization and application of graphene-based materials.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A method for preparing a graphene film with low cost and large area comprises the following steps:
the method comprises the steps of stacking a plurality of single-layer graphene oxide films, carrying out heat insulation treatment, reducing the single-layer graphene oxide films by using a flash lamp, and carrying out self-sustaining chain reduction on the single-layer graphene oxide films through thermal management.
2. The method according to claim 1, wherein the thickness of the single-layer graphene oxide film is 1-100 μm.
3. The method according to claim 2, wherein the number of stacked layers of the single-layer graphene oxide thin film is 2 to 100.
4. The method of claim 1, wherein the power of the flash lamp is 2.5-640 Ws.
5. The method of claim 1, wherein the insulated container is made of paper and/or metal.
6. The method of claim 5, wherein the metal is aluminum.
7. The method according to any one of claims 1 to 6, characterized in that a plurality of single-layer graphene oxide thin films are stacked, the top of the single-layer graphene oxide thin films does not completely cover the paper, and then a flash lamp is placed on the top of the paper for reduction;
or, a plurality of single-layer graphene oxide films are stacked and placed in a container with an open top and a metal reflective layer inside, and then a flash lamp is placed on the top of the container for reduction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210391231.4A CN114804080A (en) | 2022-04-14 | 2022-04-14 | Method for preparing graphene film in low cost and large area |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210391231.4A CN114804080A (en) | 2022-04-14 | 2022-04-14 | Method for preparing graphene film in low cost and large area |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114804080A true CN114804080A (en) | 2022-07-29 |
Family
ID=82537331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210391231.4A Pending CN114804080A (en) | 2022-04-14 | 2022-04-14 | Method for preparing graphene film in low cost and large area |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114804080A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103964424A (en) * | 2014-05-13 | 2014-08-06 | 桂林理工大学 | Method for preparing photoreduction graphene oxide thin film |
| CN106865528A (en) * | 2017-02-24 | 2017-06-20 | 湖北大学 | A kind of oxidation graphene film and its preparation method and application |
| CN109906499A (en) * | 2016-08-30 | 2019-06-18 | 斯威本科技大学 | Capacitor, electrode, redox graphene and the method and apparatus of manufacture |
| EP3702327A1 (en) * | 2019-02-27 | 2020-09-02 | Fundació Institut Català de Nanociència i Nanotecnologia (ICN2) | Amorphous highly porous reduced graphene oxide film and its applications |
| CN111943178A (en) * | 2020-08-21 | 2020-11-17 | 伊诺福科光学技术有限公司 | Method for preparing graphene material through self-sufficient reduction, graphene material, graphene film, electrode and capacitor |
-
2022
- 2022-04-14 CN CN202210391231.4A patent/CN114804080A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103964424A (en) * | 2014-05-13 | 2014-08-06 | 桂林理工大学 | Method for preparing photoreduction graphene oxide thin film |
| CN109906499A (en) * | 2016-08-30 | 2019-06-18 | 斯威本科技大学 | Capacitor, electrode, redox graphene and the method and apparatus of manufacture |
| CN106865528A (en) * | 2017-02-24 | 2017-06-20 | 湖北大学 | A kind of oxidation graphene film and its preparation method and application |
| EP3702327A1 (en) * | 2019-02-27 | 2020-09-02 | Fundació Institut Català de Nanociència i Nanotecnologia (ICN2) | Amorphous highly porous reduced graphene oxide film and its applications |
| CN111943178A (en) * | 2020-08-21 | 2020-11-17 | 伊诺福科光学技术有限公司 | Method for preparing graphene material through self-sufficient reduction, graphene material, graphene film, electrode and capacitor |
Non-Patent Citations (1)
| Title |
|---|
| SHAO ING WONG ET AL.: ""Triggering a Self-Sustaining Reduction of Graphenes Oxide for High-Performance Energy Storage Devices"", 《ACS APPLIED NANO MATERIALS》, vol. 3, no. 9, pages 9117 - 9126 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Li et al. | Scalable combustion synthesis of graphene-welded activated carbon for high-performance supercapacitors | |
| Zhao et al. | Status and prospects of MXene‐based lithium–sulfur batteries | |
| Wu et al. | A review of three-dimensional graphene-based materials: Synthesis and applications to energy conversion/storage and environment | |
| Li et al. | Three‐dimensional MXenes for supercapacitors: a review | |
| Park et al. | Characteristics tuning of graphene-oxide-based-graphene to various end-uses | |
| Yu et al. | Supercapacitor electrode materials: nanostructures from 0 to 3 dimensions | |
| Fan et al. | Carbon nanosheets: synthesis and application | |
| Chowdhury et al. | Three-dimensional graphene-based macrostructures for sustainable energy applications and climate change mitigation | |
| US20170047588A1 (en) | Porous graphene network electrodes and an all-carbon lithium ion battery containing the same | |
| Geng et al. | Constructing hierarchical carbon framework and quantifying water transfer for novel solar evaporation configuration | |
| US20150104634A1 (en) | Synthesis of three-dimensional graphene foam: use as supercapacitors | |
| CN112479189A (en) | Laser-induced graphene materials and their use in electronic devices | |
| Wen et al. | Design and fabrication of carbonized rGO/CMOF-5 hybrids for supercapacitor applications | |
| Li et al. | Recent progress of hollow carbon nanocages: general design fundamentals and diversified electrochemical applications | |
| WO2012148880A2 (en) | A method for the preparation of doped single graphene sheets | |
| Hou et al. | Scalable porous Al foil/reduced graphene oxide/Mn3O4 composites for efficient fresh water generation | |
| Tawalbeh et al. | Insights on the applications of metal oxide nanosheets in energy storage systems | |
| Sawant et al. | Advances in chemical and biomass-derived graphene/graphene-like nanomaterials for supercapacitors | |
| Gao et al. | Micro silicon–graphene–carbon nanotube anode for full cell lithium-ion battery | |
| Li et al. | A novel etching and reconstruction route to ultrathin porous TiO2 hollow spheres for enhanced photocatalytic hydrogen evolution | |
| Tang et al. | Two-dimensional materials towards separator functionalization in advanced Li–S batteries | |
| WO2019033360A1 (en) | Carbon microtube composite film electrode | |
| Chen et al. | Advanced Electrode Materials for Potassium‐Ion Hybrid Capacitors | |
| Peng et al. | Three-dimensional honeycomb-like porous carbon strutted nickel phosphide grown by analogous gel blowing for aqueous asymmetric supercapacitor | |
| CN114804080A (en) | Method for preparing graphene film in low cost and large area |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |