Nanogold-doped porous reduced graphene oxide electrode and preparation method thereof

Abstract

The invention discloses a nanogold-doped porous reduced graphene oxide electrode and a preparation method thereof.The electrode comprises a reduced graphene oxide conducting layer and a flexible substrate layer, and the reduced graphene oxide conducting layer is fixedly attached to the flexible substrate layer; the surface, facing the flexible substrate layer, of the reduced graphene oxide conducting layer is doped with nano-gold particles in a dispersed mode. The nanogold-doped porous reduced graphene oxide electrode can be prepared by taking graphene oxide, single-sided composite copper foil, chloroauric acid and the like as raw materials under conventional reaction conditions; the reduced graphene oxide conductive layer of the electrode has a certain amount of oxygen-containing functional groups, has a certain degree of surface defects and is properly doped with nanogold, so that the electrode can show relatively high and stable specific capacity when being used as a negative electrode of a lithium battery, and a measured value is stabilized at 650mAh / g or above; meanwhile, the flexible substrate layer with the overall thickness of micron order is further arranged, the flexibility is good, and great potential application to wearable equipment is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrode preparation, in particular to a kind of nano gold doped porous reduced graphene oxide electrode and preparation method thereof. BACKGROUND

[0002] Graphene is a kind of single substance of carbon, which has excellent electrical properties, and has great application value in lithium battery negative electrode material and flexible electrode etc.. Pure graphene material cannot be directly used as lithium battery negative electrode material due to the high charge-discharge platform and the lack of cycle stability, but the graphene doped or with moderate defects on the surface is a kind of composite material, which is more beneficial to the adsorption and storage of lithium ions or shows more prominent in the combination of biological probe and other specific functional structures due to the increase of sheet spacing and more active sites.

[0003] At present, graphene is mainly prepared by mechanical exfoliation or chemical vapor deposition method, and these two methods have obvious limitations, which are difficult to directly prepare the doped graphene electrode or the graphene electrode with moderate defects on the surface. Especially when graphene is used as a flexible electrode, graphene on the substrate by mechanical exfoliation and chemical vapor deposition is not convenient to combine with the flexible substrate, and there is no report on the preparation of flexible electrode by doped graphene in the prior art. SUMMARY

[0004] The present application provides a kind of nano gold doped porous reduced graphene oxide electrode and preparation method thereof, to overcome the above-mentioned deficiencies in the prior art.

[0005] The technical scheme for solving the above technical problems is as follows: a kind of nano gold doped porous reduced graphene oxide electrode, which comprises a reduced graphene oxide conductive layer and a flexible substrate layer, the reduced graphene oxide conductive layer is fixedly attached to the flexible substrate layer, and the surface of the reduced graphene oxide conductive layer towards the flexible substrate layer is dispersedly doped with nano gold particles.

[0006] On the basis of the above technical scheme, the present application can also be further selected as follows.

[0007] Specifically, the reduced graphene conductive layer is single-layer or few-layer graphene.

[0008] Specifically, the flexible substrate layer is PI film, PET film, Parylene film or PEEK film, and the thickness of the flexible substrate layer is 1-10 μm.

[0009] Specifically, the particle size of the nano gold particles is 40-120 nm.

[0010] The present application also provides a method for preparing the above-mentioned nano gold doped porous reduced graphene oxide electrode, which comprises the following steps:

[0011] S1. Preparation of graphene oxide electrolyte: graphene oxide and potassium chloride are dissolved in deionized water to obtain graphene oxide electrolyte, which is ready for use;

[0012] S2. Preparation of reduced graphene oxide conductive layer: a single-sided composite copper foil with a polished and cleaned surface is used as a cathode, and an inert electrode is used as an anode, which is immersed in the graphene oxide electrolyte prepared in S1, and electrolysis is carried out to form a reduced graphene oxide conductive layer on the surface of the single-sided composite copper foil, which is cleaned and dried to obtain a composite film material 1, which is ready for use;

[0013] S3. Surface treatment of reduced graphene oxide conductive layer: the reduced graphene oxide conductive layer on the composite film material 1 is subjected to plasma etching treatment by oxygen plasma to form a relatively uniform defect on the surface of the reduced graphene oxide conductive layer, and the composite film material 2 is obtained, which is ready for use;

[0014] S4. Nano-gold doping of reduced graphene oxide conductive layer: an aqueous solution of chloroauric acid is prepared, and the composite film material 2 with a surface defect in S3 is immersed in the aqueous solution of chloroauric acid, and after sufficient soaking, heating, slow stirring, and dropwise addition of sodium citrate aqueous solution, the composite film material 3 is obtained after sufficient reaction, ultrasonic cleaning, and drying, which is ready for use;

[0015] S5. Preparation of flexible substrate layer: a flexible substrate layer is deposited on the surface of the composite film material 3 doped with nano-gold by physical vapor deposition to obtain a composite film material 4, which is ready for use;

[0016] S6. Removal of single-sided composite copper foil: the inherent plastic film layer on the single-sided composite copper foil in the composite film material 4 is removed by plasma etching, and then the composite film material 4 is immersed in an electrolyte, and the composite film material 4 is used as an anode for electrolysis to remove the copper foil layer on the single-sided composite copper foil, and then the composite film material 4 is washed, dried, and cut to obtain a nano-gold doped porous reduced graphene oxide electrode.

[0017] On the basis of the above preparation method, the present application has the following further specific selection.

[0018] Specifically, the concentration of graphene oxide and potassium chloride in the graphene oxide electrolyte of step S1 is 0.6-1.2 mg / mL and 0.04-0.06 mol / L, respectively.

[0019] Specifically, the copper foil layer on the single-sided composite copper foil is uniformly polished by using 800-1000 grit sandpaper in step S2, and the reaction conditions for electrolysis are as follows: scan rate 80-120 mV / s, and duration 80-100 min.

[0020] Specifically, the process conditions of the plasma etching treatment in step S3 are as follows: oxygen flow rate 80-100 mL / min, power 240-260 W, uniform etching, and average etching time of each place 8-12 s.

[0021] Specifically, the concentration of the chloroauric acid aqueous solution in step S4 is 0.8-1.1 mmol / L, and the concentration of the sodium citrate is 25-35 mmol / L.

[0022] Specifically, the sulfuric acid used in the acid washing in step S6 has a concentration of 0.5-1 mol / L, and the electrolysis is stopped when gas is generated on the anode.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The present application successfully prepares a nano-gold-doped porous reduced graphene oxide electrode under conventional reaction conditions by using graphene oxide, single-sided composite copper foil, chloroauric acid and the like as raw materials. The electrode has a reduced graphene oxide conductive layer and a flexible substrate layer, and nano-gold is doped and dispersed between the two layers. The nano-gold is combined with the defect sites on the reduced graphene oxide conductive layer, and is positioned by the covered flexible substrate layer, thereby avoiding agglomeration and ensuring long-term stability and excellent electrical performance of the electrode. The reduced graphene oxide conductive layer of the electrode has a certain amount of oxygen-containing functional groups and a certain degree of surface defects, and is moderately doped with nano-gold. Therefore, the electrode can exhibit a high and stable specific capacity when used as a lithium battery negative electrode, and the measured value is stably above 650 mAh / g. The present application provides a new method for combining single-layer or few-layer graphene doped with nano-gold on the surface of a flexible plastic film. The electrode prepared by the method is a flexible electrode that can be cut arbitrarily, has good conductivity and weather resistance, is resistant to washing, and has great potential application value in the field of flexible wearable electronic devices. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A cross-sectional schematic view of a nano-gold-doped porous reduced graphene oxide electrode provided by the present application is shown in the figure.

[0026] Figure 2 A flowchart of the preparation of a nano-gold-doped porous reduced graphene oxide electrode by the present application is shown in the figure.

[0027] In the figure, the components represented by each number are listed as follows:

[0028] 1. Reduced graphene oxide conductive layer; 2. Flexible substrate layer; 3. Nano-gold; 4. Copper foil layer; 5. Plastic film layer. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be clearly and completely described below with reference to the drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0030] For the sake of brevity, the raw materials used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0031] As shown in Figure 1 The present application provides a kind of nano gold doped porous reduced graphene oxide electrode, it includes reduced graphene oxide conductive layer 1 and flexible substrate layer 2, reduced graphene oxide conductive layer is fixedly attached to the flexible substrate layer 2, the surface of the flexible substrate layer 2 is dispersedly doped with nano gold particles 3 towards the reduced graphene oxide conductive layer, and the reduced graphene oxide conductive layer is single-layer or few-layer graphene.

[0032] It should be noted that the flexible substrate layer is a PI film, a PET film, a Parylene film or a PEEK film, and the thickness of the flexible substrate layer is 1-10 μm; the particle size of the nano gold particles is 40-120 nm, and the detected distribution density of the nano gold particles on the surface of the reduced graphene oxide conductive layer is about 15-65 per square micron.

[0033] Example 1

[0034] A nano gold doped porous reduced graphene oxide electrode is prepared by the following method:

[0035] S1. Preparation of graphene oxide electrolyte: graphene oxide and potassium chloride are dissolved in deionized water to obtain a graphene oxide electrolyte, wherein the concentrations of graphene oxide and potassium chloride in the graphene oxide electrolyte are 0.6 mg / mL and 0.06 mol / L, respectively;

[0036] S2. Preparation of reduced graphene oxide conductive layer: the surface of the copper foil layer 4 on the single-sided composite copper foil is uniformly polished using No. 800 sandpaper, then the single-sided composite copper foil after polishing is used as a cathode, an inert electrode is used as an anode, the single-sided composite copper foil is immersed in the graphene oxide electrolyte prepared in S1, and electrolysis is carried out at a scanning rate of 120 mV / s for 80 min, to form a reduced graphene oxide conductive layer on the surface of the single-sided composite copper foil, which is then washed and dried to obtain a composite film material one for standby use;

[0037] S3. Surface treatment of the reduced graphene oxide conductive layer: the reduced graphene oxide conductive layer on the composite material one is subjected to plasma etching treatment by oxygen plasma, the oxygen flow rate is 100 mL / min, the power is 240 W, uniform etching, the average etching time of each place is between 12 s, and a relatively uniform defect is formed on the surface of the reduced graphene oxide conductive layer after the treatment, thereby obtaining a composite material two for standby;

[0038] S4. Nano-gold doping of the reduced graphene oxide conductive layer: an aqueous solution of chloroauric acid is prepared, and the composite material two with a surface defect in S3 is immersed in the aqueous solution of chloroauric acid, the concentration of the aqueous solution of chloroauric acid is 1.1 mmol / L, after sufficient soaking, heating, slow stirring, and dropwise addition of an aqueous solution of sodium citrate, the concentration of the aqueous solution of sodium citrate is 25 mmol / L, after sufficient reaction, ultrasonic cleaning, and drying, a composite material three is obtained for standby;

[0039] S5. Preparation of a flexible substrate layer: a flexible substrate layer is deposited on the surface of the composite material three doped with nano-gold by physical vapor deposition, thereby obtaining a composite material four for standby;

[0040] S6. Removal of a single-sided composite copper foil: the inherent plastic film layer 5 on the single-sided composite copper foil of the composite material four is removed by plasma etching, 0.5 mol / L sulfuric acid is used for acid washing (to remove possible copper oxide on the surface), and then the composite material four is used as an anode in a 1-2 mol / L copper sulfate solution to electrolytically remove the copper foil layer 4 on the single-sided composite copper foil (when the plastic film layer is etched, it is not necessary to completely remove the plastic film layer, as long as the copper foil layer is exposed to a considerable extent, after the copper foil layer is removed by electrolysis, the remaining residual plastic film layer is automatically detached), the electrolysis is stopped when gas is generated at the anode, washed, dried, and cut, thereby obtaining a nano-gold doped porous reduced graphene oxide electrode.

[0041] Example 2

[0042] A nano-gold doped porous reduced graphene oxide electrode is prepared by the following method:

[0043] S1. Preparation of an oxidized graphene electrolyte: oxidized graphene and potassium chloride are dissolved in deionized water to obtain an oxidized graphene electrolyte, wherein the concentrations of the oxidized graphene and the potassium chloride in the oxidized graphene electrolyte are 0.9 mg / mL and 0.05 mol / L, respectively;

[0044] S2. Preparation of reduced graphene oxide conductive layer: The surface of the copper foil layer on the single-sided composite copper foil was uniformly polished using 1000-grit sandpaper. Then, the polished single-sided composite copper foil was used as the cathode, and an inert electrode was used as the anode. The electrodes were immersed in the graphene oxide electrolyte prepared in S1, and electrolysis was performed at a scan rate of 100 mV / s for 90 min. A reduced graphene oxide conductive layer was formed on the surface of the single-sided composite copper foil. After cleaning and drying, a composite film material 1 was obtained for standby use.

[0045] S3. Surface treatment of reduced graphene oxide conductive layer: The reduced graphene oxide conductive layer on the composite film material 1 was subjected to plasma etching treatment using oxygen plasma. The oxygen flow rate was 90 mL / min, and the power was 250 W. The average etching time for each location was between 10 s. After treatment, a relatively uniform defect was formed on the surface of the reduced graphene oxide conductive layer, and a composite film material 2 was obtained for standby use.

[0046] S4. Nano-gold doping of reduced graphene oxide conductive layer: An aqueous chloroauric acid solution was prepared, and the composite film material 2 with surface defects from S3 was immersed in the aqueous chloroauric acid solution. The concentration of the aqueous chloroauric acid solution was 0.9 mmol / L. After sufficient soaking, heating and slow stirring were performed, and an aqueous sodium citrate solution was added dropwise. The concentration of the aqueous sodium citrate solution was 30 mmol / L. After sufficient reaction, ultrasonic cleaning was performed, and the composite film material 3 was obtained for standby use after drying.

[0047] S5. Preparation of flexible substrate layer: A flexible substrate layer was deposited on the surface of the composite film material 3 doped with nano-gold using physical vapor deposition, and a composite film material 4 was obtained for standby use.

[0048] S6. Removal of single-sided composite copper foil: The inherent plastic film layer on the single-sided composite copper foil in the composite film material 4 was removed using plasma etching. Acid washing was performed using sulfuric acid with a concentration of 0.8 mol / L, followed by electrolysis in a copper sulfate solution with a concentration of 1-2 mol / L, using the composite film material 4 as the anode. The electrolysis was stopped when gas was generated at the anode. After washing and drying, the nano-gold doped porous reduced graphene oxide electrode was obtained by cutting.

[0049] Example 3

[0050] A nano-gold doped porous reduced graphene oxide electrode is prepared by the following method:

[0051] S1. Preparation of graphene oxide electrolyte: Graphene oxide and potassium chloride were dissolved in deionized water to obtain a graphene oxide electrolyte. The concentrations of graphene oxide and potassium chloride in the graphene oxide electrolyte were 1.2 mg / mL and 0.04 mol / L, respectively.

[0052] S2. Preparation of reduced graphene oxide conductive layer: the surface of the copper foil layer on the single-sided composite copper foil was uniformly polished using No. 900 sandpaper, then the single-sided composite copper foil after polishing was used as the cathode, the inert electrode was used as the anode, and the single-sided composite copper foil was immersed in the graphene oxide electrolyte prepared in S1, and electrolysis was carried out at a scanning rate of 80 mV / s for 100 min. A reduced graphene oxide conductive layer was formed on the surface of the single-sided composite copper foil, which was washed and dried to obtain composite film material 1 for standby;

[0053] S3. Surface treatment of reduced graphene oxide conductive layer: the reduced graphene oxide conductive layer on the composite film material 1 was subjected to plasma etching treatment with oxygen plasma, the oxygen flow rate was 80 mL / min, the power was 260 W, and the average etching time of each place was between 8 s. After treatment, a relatively uniform defect was formed on the surface of the reduced graphene oxide conductive layer to obtain composite film material 2 for standby;

[0054] S4. Nano-gold doping of reduced graphene oxide conductive layer: an aqueous solution of chloroauric acid was prepared, and the composite film material 2 with surface defects in S3 was immersed in the aqueous solution of chloroauric acid. The concentration of the aqueous solution of chloroauric acid was 0.8 mmol / L. After sufficient soaking, heating, slow stirring, and dropwise addition of an aqueous solution of sodium citrate with a concentration of 35 mmol / L, the reaction was carried out. After sufficient reaction, ultrasonic cleaning and drying, composite film material 3 was obtained for standby;

[0055] S5. Preparation of flexible substrate layer: a flexible substrate layer was deposited on the surface of the composite film material 3 doped with nano-gold by physical vapor deposition to obtain composite film material 4 for standby;

[0056] S6. Removal of single-sided composite copper foil: the inherent plastic film layer on the single-sided composite copper foil in the composite film material 4 was removed by plasma etching, and the composite film material 4 was used as the anode in a 1-2 mol / L copper sulfate solution. When gas was generated at the anode, the electrolysis was stopped, and the composite film material 4 was washed and dried. The nano-gold doped porous reduced graphene oxide electrode was obtained by cutting.

[0057] The performance of the nano-gold doped porous reduced graphene oxide electrode prepared in Embodiments 1 to 3 is tested, and when used as a lithium battery negative electrode material, each embodiment is detected for multiple times, and the detection results show that the specific capacity measurement value is stable at above 650 mAh / g, and after standing for 60 days under indoor daily environment, the measurement value is not obviously changed, while the corresponding specific capacity of a commercially available graphite negative electrode detected by the same method is about 330 mAh / g, that is, the nano-gold doped porous reduced graphene oxide electrode prepared in the application has excellent performance. In addition, the nano-gold doped porous reduced graphene oxide electrode prepared in the application has only a micron-level thickness and excellent flexibility, and can still maintain good conductive performance when cut to a millimeter level, and has good potential application value on wearable devices.

[0058] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A nano-gold doped porous reduced graphene oxide electrode, characterized in that: The invention comprises a reduced graphene oxide conductive layer and a flexible substrate layer, wherein the reduced graphene oxide conductive layer is fixedly attached to the flexible substrate layer, and the surface of the reduced graphene oxide conductive layer facing the flexible substrate layer is doped with nano-gold particles.

2. The nano-gold-doped porous reduced graphene oxide electrode according to claim 1, characterized in that: The reduced graphite oxide conductive layer is a single layer or a few layers of graphene.

3. The nano-gold-doped porous reduced graphene oxide electrode according to claim 1, characterized in that: The flexible substrate layer is a PI film, a PET film, a Parylene film or a PEEK film, and the thickness of the flexible substrate layer is 1-10 μm.

4. The gold nanoparticle-doped porous reduced graphene oxide electrode according to any one of claims 1 to 3, characterized in that: The particle size of the gold nanoparticles is 40-120 nm.

5. A method for preparing the nano-gold-doped porous reduced graphene oxide electrode according to any one of claims 1 to 4, characterized in that: The steps include: S1. Preparation of graphene oxide electrolyte: dissolving graphene oxide and potassium chloride in deionized water to obtain graphene oxide electrolyte, set aside; S2. Preparation of a conductive layer of reduced graphene oxide: A single-sided composite copper foil with a polished and cleaned surface was used as a cathode and an inert electrode as an anode. The cathode was immersed in the graphene oxide electrolyte prepared in S1 and electrolyzed to form a conductive layer of reduced graphene oxide on the surface of the single-sided composite copper foil. The conductive layer was washed and dried to obtain a composite film material for standby use. S3. Surface treatment of the reduced graphene oxide conductive layer: plasma etching of the reduced graphene oxide conductive layer on a composite film material using oxygen plasma to form relatively uniform defects on the surface of the reduced graphene oxide conductive layer to obtain a composite film material II, set aside; S4. The conductive layer of reduced graphene oxide was doped with gold nanoparticles: an aqueous solution of chloroauric acid was prepared, and the composite film material with surface defects in S3 was immersed in an aqueous solution of chloroauric acid. After sufficient immersion, the composite film material was heated, slowly stirred, and an aqueous solution of sodium citrate was added dropwise. After sufficient reaction, the composite film material was ultrasonically cleaned and dried to obtain a composite film material three for later use. S5. Preparation of a flexible substrate layer: A flexible substrate layer is deposited on the surface of the composite film material three doped with nano-gold by physical vapor deposition to obtain a composite film material four, set aside; S6. Removal of single-sided composite copper foil: Use plasma etching to remove the inherent plastic film layer on the single-sided composite copper foil in composite film material four, pickle it, and then immerse it in an electrolyte. Use composite film material four as the anode to perform electrolysis to remove the copper foil layer on the single-sided composite copper foil. Wash, dry, and cut it to obtain a nano-gold-doped porous reduced graphene oxide electrode.

6. The method for preparing a nano-gold-doped porous reduced graphene oxide electrode according to claim 5, characterized in that: The concentrations of graphene oxide and potassium chloride in the graphene oxide electrolyte of step S1 are 0.6-1.2 mg / mL and 0.04-0.06 mol / L, respectively.

7. The method for preparing a nano-gold-doped porous reduced graphene oxide electrode according to claim 5, characterized in that: In step S2, the surface of the copper foil layer on the single-sided composite copper foil is evenly polished using 800-1000 sandpaper, and the reaction conditions for electrolysis are: scanning rate 80-120mV / s, lasting 80-100min.

8. The method for preparing a nano-gold-doped porous reduced graphene oxide electrode according to claim 5, wherein: The process conditions for the plasma etching treatment in step S3 are: oxygen flow rate 80-100 mL / min, power 240-260 W, uniform etching, and an average etching time of 8-12 s per location.

9. The method for preparing a nano-gold-doped porous reduced graphene oxide electrode according to claim 5, characterized in that: In step S4, the concentration of the chloroauric acid aqueous solution is 0.8-1.1 mmol / L, and the concentration of sodium citrate is 25-35 mmol / L.

10. The method for preparing a nano-gold-doped porous reduced graphene oxide electrode according to any one of claims 5 to 9, characterized in that: In step S6, sulfuric acid with a concentration of 0.5-1 mol / L is used for pickling, and the electrolysis is stopped when gas is generated on the anode during electrolysis to remove the copper foil layer.

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