CN104085884B

CN104085884B - A kind of with hydrogen (H2) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property

Info

Publication number: CN104085884B
Application number: CN201410331508.XA
Authority: CN
Inventors: 李洁; 王奇; 韦娟; 陈长伦; 王祥科
Original assignee: Institute of Plasma Physics of CAS
Current assignee: Institute of Plasma Physics of CAS
Priority date: 2014-07-11
Filing date: 2014-07-11
Publication date: 2016-05-18
Anticipated expiration: 2034-07-11
Also published as: CN104085884A

Abstract

The present invention relates to a kind of with hydrogen (H₂) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property, GO is spin-coated on ITO electro-conductive glass, oven dry is placed in plasma discharge chamber, in arc chamber, be connected to graphite electrode, electrode connects a radio frequency AC power, and this power supply can produce inductively-coupled plasma sources, before electric discharge, first pass into argon gas, drive air away, then open vavuum pump and be evacuated to 2? Pa left and right, passes into H₂With Ar mist. H₂With Ar total gas couette be 3? sccm, H₂With the flow-rate ratio of Ar be 2/1, now open AC power and produce hydrogen and argon hybrid plasma, does is AC power 70? does w, act directly on this plasma flow on GO film, electric discharge 5? after min, obtain redox graphene (rGO) film. The method can not only effectively be reduced GO, and fast, efficient, the green impurity of not introducing simultaneously. Does is as electrode material, the specific capacity of rGO film 211.8 by the rGO film making? F/g, the specific capacity of the reduced graphene obtaining higher than other method of reducing.

Description

A kind of with hydrogen (H2) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property

Technical field

The present invention relates to a kind of with hydrogen (H₂) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property.

Background technology

Graphene has unique performances such as high, the theoretical specific area of electric conductivity is large, is a kind of desirable electrode material for super capacitor. Graphene oxide (GO), can be produced in batches by cheap graphite powder, but the existence of oxygen functional group has changed the electrical properties of Graphene. Prepare Graphene by reduction GO and be considered to produce in a large number a kind of the most promising method of Graphene. The method of existing reduction GO is mainly to use various strong reductants, for example: hydrazine hydrate, anhydrous hydrazine, boric acid hydrogen sodium etc. This method is consuming time, production efficiency is low, process is complicated, and hydrazine hydrate and anhydrous hydrazine be the chemical substance of poisonous danger, also can introduce impurity simultaneously. Plasma technique is lower temperature plasma technology particularly, has advantages of that additive method is incomparable preparing aspect material. In low temperature plasma, contain various active particles and make it have efficient electrochemical properties, therefore, utilize gas discharge to produce the particle with reproducibility, thereby reduction GO is quick, efficient, green, simple, is a kind of method of novelty.

According to the difference of working gas character, plasma can be divided into reactive gas plasma and inert gas plasma. Inert gas plasma is taking Ar plasma as representative, and this plasma mainly plays bombardment and corrasion to material, is a kind of physical action. And between various reactive gas plasmas, there is larger difference. H₂The features such as plasma has concentration of energy, and heat enthalpy value is high, and thermal conductivity is strong, at high temperature H₂Reducing power also greatly improve. Ar can promote H by ionization₂The increase of plasma quantity. H₂With Ar mixed gas discharge, merge bombardment effect and the H of Ar₂Reduction. Lower temperature plasma technology has boundless prospect in nano material aspect preparing.

Summary of the invention

In order to overcome existing preparation method's process complexity, be easy to introduce impurity, consuming time, etc. deficiency, the invention provides one and should apply H₂Method with Ar hybrid plasma reduction GO. The method can not only efficiently be reduced GO, can also make preparation time shorten dramatically, and process is greatly simplified. The redox graphene (rGO) obtaining has very high specific discharge capacity.

To achieve these goals, the present invention adopts following technical scheme:

A kind of with hydrogen (H₂) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property, it is characterized in that, comprise the following steps:

A, by ultrasonic dispersed a certain amount of Graphene GO solution, then with spin coating instrument, Graphene GO is spin-coated in the substrate of tin indium oxide ITO electro-conductive glass, spin coating instrument speed is 2950-3050rpm, the spin coating time is 88-92s, then be placed in dry 4-6min on the warm table of 58-62 ° of C, obtain the Graphene GO film of oven dry;

B, the ITO electro-conductive glass that is loaded with Graphene GO film is placed in to plasma discharge chamber, by regulating parameter, in arc chamber, produces H₂With Ar hybrid plasma stream, this hybrid plasma stream is acted directly on to the surface of GO film, after electric discharge certain hour, make reduced graphene (rGO) film.

Described hydrogen (H for one₂) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property, it is characterized in that: the GO dispersion liquid concentration described in steps A is 5mg/mL, spin speed is 3000rpm, the spin coating time is 90s, baking temperature is 60 ° of C, and be 5min drying time.

Described hydrogen (H for one₂) and argon (Ar) hybrid plasma redox graphene (GO) improve the method for chemical property, it is characterized in that: in the plasma discharge chamber described in step B, connect by graphite electrode, electrode connects an AC power that can produce inductively-coupled plasma sources, before electric discharge, first pass into Ar, with deaeration, then be evacuated to 2Pa left and right, open H₂With Ar valve, H in adjust flux meter₂With the flow of Ar, then regulate the pressure in plasma discharge chamber, finally regulate AC power power, the hybrid plasma stream of generation acts directly on the surface of GO film, and the pressure in plasma discharge chamber is 4.7Pa, and total gas couette is 3sccm, H₂With Ar flow-rate ratio be 2:1, action time is 5min, AC power is 70w.

Beneficial effect of the present invention:

1、H₂Plasma has reproducibility, can reduce to the oxygen-containing functional group on GO surface. Ar can promote H by ionization₂The increase of plasma quantity. This hybrid plasma method has merged bombardment effect and the H of Ar₂Reduction, also do not introduce unnecessary impurity element, efficient, green, be the very promising technology of preparing of one;

2, this hybrid plasma method can not only be reduced GO efficiently, and electro-chemical test shows, as electrode material, the GO electrochemical impedance after reduction has reduced, and specific capacity is greatly improved simultaneously.

The rGO thin film electrochemistry performance that the inventive method obtains is greatly improved, and as electrode material, the GO film specific capacity obtaining is 22.7F/g, and the specific capacity of rGO film is 211.8F/g.

Brief description of the drawings

Fig. 1 is the present invention's auto levelizer schematic diagram used,

In Fig. 1: 1, plasma discharge chamber; 2, graphite electrode; 3, AC power; 4, flowmeter; 5, mechanical pump; 6, molecular pump; 7, pressure gage.

Fig. 2 is H₂With the emission spectrum OES figure of Ar hybrid plasma, in figure, transverse axis wavelength is wavelength, and longitudinal axis Intensity is intensity.

Fig. 3 A is that the SEM (SEM) of GO characterizes, and Fig. 3 B is that the SEM (SEM) of rGO characterizes.

Fig. 4 is the C1sXPS collection of illustrative plates of GO and rGO, and in figure, transverse axis Bindingenergy is that longitudinal axis Intensity is intensity in conjunction with energy.

Fig. 5 is that the Raman of GO and rGO characterizes, and in figure, transverse axis wavelength is wavelength, and longitudinal axis Intensity is intensity.

Fig. 6 is GO and the cyclic voltammetry curve of rGO in the 5mmol/L potassium ferricyanide/potassium ferrocyanide electrolyte.

Fig. 7 is GO and the cyclic voltammetry curve of rGO in 6mol/L potassium hydroxide electrolyte, and in figure, transverse axis potential is voltage, and longitudinal axis currentdensity is current density.

Fig. 8 be GO and rGO in 6mol/L potassium hydroxide electrolyte charging and discharging curve, in figure, transverse axis T ime is the time, longitudinal axis potential is voltage.

Fig. 9 is GO and the Nyquist curve of rGO in 6mol/L potassium hydroxide electrolyte, and in figure, transverse axis potential is voltage, and longitudinal axis currentdensity is current density.

Detailed description of the invention

Embodiment 1

One H₂Method with Ar plasma deoxidization GO raising chemical property, comprises the following steps:

A, by ultrasonic dispersed the GO solution of 5mg/mL, then with spin coating instrument, GO is spin-coated in the substrate of ITO electro-conductive glass, spin coating instrument speed is 3000rpm, the spin coating time is 90s, is then placed in dry 5min on the warm table of 60 ° of C, obtains the GO film of oven dry;

B, the ITO electro-conductive glass that is loaded with GO film is placed in to plasma discharge chamber 1 (see figure 1), in arc chamber, be connected to graphite electrode 2, electrode connects an AC power 3, this power supply can produce inductively-coupled plasma sources, in arc chamber, first pass into argon gas, drive air away, then open vavuum pump and be evacuated to 2Pa, now open AC power 3 and produce H₂With Ar hybrid plasma stream, this hybrid plasma stream is acted directly on to the surface of film, discharge and made rGO film.

The H that applies₂See Fig. 2 with the OES of Ar hybrid plasma stream, Fig. 3 is shown in by ESEM (SEM) photo of prepared GO and rGO film.

In the C1sXPS spectrogram (Fig. 4) of GO and rGO, can find out in the peak of C1s of GO and contain C=C (284.6eV), C-O (286.1eV), C=O (287.5eV) peak, illustrates in the structure of Graphene and contains the carbon and oxygen functional group such as carboxyl, hydroxyl. And C-O (286.1eV) intensity obviously reduces in the peak of the C1s of rGO, C=O (287.5eV) peak has disappeared, and C=C (284.6eV) peak intensity increases greatly, and this absolutely proves that GO has obtained reduction significantly.

Fig. 5 is the Raman collection of illustrative plates of GO and rGO, and the absworption peak of G band is corresponding to carbon atom Mian center E in graphite-structure₂Vibration, the absworption peak of D band is corresponding to the carbon atom vibration on edge, defect and carbon and oxygen functional group in graphene-structured. D band and the G band that can find out GO and rGO all do not have significantly skew, the I of GO and rGO_D/I_GValue is respectively 0.9966 and 0.9370, and the I of Graphene in plasma treatment procedure is described_D/I_GThere is reduction in value, the removing of this minimizing owing to carbon and oxygen functional group in middle graphene-structured and carbonyl functional group can be reduced the quantity at edge and defect in rGO.

Fig. 6 carries out with three-electrode system 100mV/s in the potassium ferricyanide/potassium ferrocyanide solution of 5mmol/L the cyclic voltammetry curve that cyclic voltammetry scan obtains, and in figure, transverse axis potential is voltage, and longitudinal axis currentdensity is current density. As can be seen from the figure, after GO reduction, chemical property is greatly improved.

Fig. 7 is that in the potassium hydroxide solution of 6mol/L, 100mV/s carries out the cyclic voltammetry curve that cyclic voltammetry scan obtains with three-electrode system. As we can see from the figure, with respect to GO, rGO cyclic voltammetry curve shows as irregular rectangle and has larger integral area, illustrates that rGO has relatively high specific capacity. Calculating GO specific capacity is 22.7F/g, and the specific capacity of rGO is 211.8F/g. The specific capacity of rGO prepared by the present invention is greater than the specific capacity of the rGO that other method of reducing obtain.

Fig. 8 be GO and rGO in 6mol/L potassium hydroxide electrolyte charging and discharging curve. The charging and discharging curve of GO and rGO all shows as symmetrical triangle, but in the time that electric discharge starts, the potential drop of rGO is lower than GO, illustrates as electrode material, and the internal resistance of rGO is less than GO.

Fig. 9 is GO and the Nyquist curve of rGO in 6mol/L potassium hydroxide electrolyte. Illustration is electrochemical impedance spectroscopy simulating equivalent circuit figure. From figure, can obviously find out GO and rGO ohmage (RS) be worth almost equal, but rGORCt value is obviously less than GO, illustrates that rGO material has less electrochemical impedance, has better electric conductivity, has further proved that it has more superior chemical property.

Claims

1. a method that improves chemical property with hydrogen and argon hybrid plasma redox graphene, is characterized in that, comprises the following steps:

A, by ultrasonic dispersed a certain amount of graphene oxide GO solution, then with spin coating instrument, Graphene GO is spin-coated in the substrate of tin indium oxide ITO electro-conductive glass, spin coating instrument speed is 2950-3050rpm, the spin coating time is 88-92s, then be placed in dry 4-6min on the warm table of 58-62 ° of C, obtain the graphene oxide GO film of oven dry;

B, the ITO electro-conductive glass that is loaded with graphene oxide GO film is placed in to plasma discharge chamber, by regulating parameter, in arc chamber, produces H₂With Ar hybrid plasma stream, this hybrid plasma stream is acted directly on to the surface of GO film, after electric discharge certain hour, make reduced graphene film;

In plasma discharge chamber described in step B, connect by graphite electrode, electrode connects an AC power that can produce inductively-coupled plasma sources, first passes into Ar before electric discharge, with deaeration, is then evacuated to 2Pa left and right, opens H₂With Ar valve, H in adjust flux meter₂With the flow of Ar, then regulate the pressure in plasma discharge chamber, finally regulate AC power power, the hybrid plasma stream of generation acts directly on the surface of GO film, and the pressure in plasma discharge chamber is 4.7Pa, and total gas couette is 3sccm, H₂With Ar flow-rate ratio be 2:1, action time is 5min, AC power is 70w.

2. a kind of method that improves chemical property with hydrogen and argon hybrid plasma redox graphene according to claim 1, it is characterized in that: the GO dispersion liquid concentration described in steps A is 5mg/mL, spin speed is 3000rpm, the spin coating time is 90s, baking temperature is 60 ° of C, and be 5min drying time.