CN106268820A - The nanocrystalline graphene composite material of cobalt protoxide, its preparation method and application - Google Patents
The nanocrystalline graphene composite material of cobalt protoxide, its preparation method and application Download PDFInfo
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- CN106268820A CN106268820A CN201610649362.2A CN201610649362A CN106268820A CN 106268820 A CN106268820 A CN 106268820A CN 201610649362 A CN201610649362 A CN 201610649362A CN 106268820 A CN106268820 A CN 106268820A
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Abstract
The embodiment of the invention discloses a kind of nanocrystalline graphene composite material of cobalt protoxide, Graphene in this composite is in the form of sheets, and cobalt protoxide is nanocrystalline is dispersed on Graphene, the embodiment of the invention also discloses the preparation method of this composite and in the application of catalytic field.With Graphene as substrate in the present invention, obtain the nanocrystalline graphene composite material of cobalt protoxide by the reduction of thermal decomposition method one step, without Co in this composite3O4Or simple substance Co, has obtained pure CoO, and CoO is nanocrystalline is uniformly dispersed, and soilless sticking phenomenon, so that this composite is while having good absorbing property and magnetic property so that it is catalytic performance has obtained the biggest improvement.
Description
Technical field
The present invention relates to field of material preparation, particularly to a kind of cobalt protoxide nanocrystalline-graphene composite material, its system
Preparation Method and application.
Background technology
Cobalt protoxide (CoO), as typical transition metal oxide, has a thing phase of two kinds of typical stable existences, i.e. in
(space group is P6 for the rock-salt phase (space group is Fm3m) of buff and greeny wurtzit phase3mc).CoO is excellent
Magnetic material, near its Neel temperature (298K), there is paramagnetic and the transformation of diamagnetic body.Block CoO material is insulation
Antiferromagnetic materials, but the CoO of nanostructured (nano Co O) material shows good ferromagnetism or superparamagnetism.Receive
Rice CoO material has physically better and chemical property, and it is at lithium ion battery, electro-magnetic wave absorption, catalysis, gas transmission and magnetic
The aspects such as data storage device are respectively provided with and are widely applied.
In many application of nano Co O material, catalytic performance is the focus of research.Such as, CoO nano wire can be catalyzed and divide
Solve the harmful organic substance in air and water body, mesoporous Mn3O4CO catalysis oxidation and redox reactions (ORR) are presented by-CoO
Preferably catalytic performance etc..
But, in existing nano Co O material, often contain Co3O4Or simple substance Co, obtains pure CoO and has one
Fixed difficulty.Meanwhile, the nanocrystalline easy reunion of CoO, affect the catalytic performance of nano Co O material.
Summary of the invention
The embodiment of the invention discloses a kind of cobalt protoxide nanocrystalline-graphene composite material, its preparation method and application,
Impurity and the problem of the nanocrystalline easy reunion of nano Co O is contained with the existing nano Co O material of solution.Technical scheme is as follows:
First aspect, embodiments provide a kind of cobalt protoxide nanocrystalline-graphene composite material, described graphite
In the form of sheets, and described cobalt protoxide is nanocrystalline is dispersed on described Graphene for alkene.
Wherein, described cobalt protoxide is nanocrystalline for face-centred cubic structure.
Wherein, the nanocrystalline particle diameter of described cobalt protoxide is 1-6nm, and mean diameter is 3nm.
Second aspect, the embodiment of the present invention additionally provides the preparation method of described composite, including:
Graphite oxide joined in N-Methyl pyrrolidone and carry out dispersion process, obtaining mixed liquor；
Acetylacetone cobalt and 18-amine. are added to described mixed liquor, under stirring, described mixed liquor is heated to
120-140 DEG C, it is incubated more than 30 minutes, then proceedes to, under stirring, be heated to 190-202 DEG C, be incubated more than 2 hours；
Add organic solvent to stop sudden for reaction, isolate product, and described product is washed and is dried
Process；
Wherein, described acetylacetone cobalt and described graphite oxide ratio are 1mol:(20-40) g, described graphite oxide and institute
The mass ratio stating 18-amine. is 1:(12.5-50), described N-Methyl pyrrolidone is 1L:1g with the ratio of described graphite oxide.
Preferably, described dispersion is processed as ultrasonic disperse process.
Preferably, it is heated to 190-202 DEG C, particularly as follows: be heated to 202 DEG C described in.
Preferably, described organic solvent is ethanol.
Preferably, described carrying out washing treatment is: carry out alternately carrying out washing treatment with normal hexane and acetone.
The third aspect, the embodiment of the present invention additionally provides the application at catalytic field of the described composite.
Visible, with Graphene as substrate in this programme, by thermal decomposition method one step reduction obtain cobalt protoxide nanocrystalline-stone
Ink alkene composite, without Co in this composite3O4Or simple substance Co, has obtained pure CoO, and the nanocrystalline dispersion of CoO is equal
Even, soilless sticking phenomenon, so that this composite is while having good absorbing property and magnetic property so that it is catalytic performance
Obtain the biggest improvement.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to
Other accompanying drawing is obtained according to these accompanying drawings.
Fig. 1 be graphite oxide (GO), Graphene (GN) and the embodiment of the present invention 1 preparation cobalt protoxide nanocrystalline-graphite
The XRD figure of alkene composite；
Fig. 2 be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-the XPS spectrum figure of graphene composite material；
Fig. 3 be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-electron microscope picture of graphene composite material；
Fig. 4 be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-loss of the microwave reflection rate of graphene composite material
Value and thickness of sample, the graph of a relation of frequency；
Fig. 5 be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-intensity of magnetization of graphene composite material and temperature
Graph of a relation；
Fig. 6 be the embodiment of the present invention 1 preparation cobalt protoxide nanocrystalline-graphene composite material catalysis reduction CO2Electricity
Current density and the graph of a relation of current potential.
Detailed description of the invention
The embodiment of the invention discloses a kind of cobalt protoxide nanocrystalline-graphene composite material, wherein, Graphene (GN) in
Two-dimensional slice stratiform, on the nanocrystalline lamella being dispersed in Graphene of cobalt protoxide (CoO).This cobalt protoxide is nanocrystalline-and Graphene is multiple
CoO in condensation material is nanocrystalline for face-centred cubic structure, and particle diameter is 1-6nm, and mean diameter is about 3nm.
The embodiment of the invention also discloses this cobalt protoxide nanocrystalline-preparation method of graphene composite material, can wrap
Include following steps:
Graphite oxide joined in N-Methyl pyrrolidone and carry out dispersion process, obtaining mixed liquor；
Acetylacetone cobalt and 18-amine. are added to described mixed liquor, under stirring, described mixed liquor is heated to
120-140 DEG C, it is incubated more than 30 minutes, then proceedes to, under stirring, be heated to 190-202 DEG C, be incubated more than 2 hours；
Add organic solvent to stop sudden for reaction, isolate product, and described product is washed and is dried
Process；
Wherein, described acetylacetone cobalt and described graphite oxide ratio are 1mol:(20-40) g, described graphite oxide and institute
The mass ratio stating 18-amine. is 1:(12.5-50), described N-Methyl pyrrolidone is 1L:1g with the ratio of described graphite oxide.
Graphene is the two dimensional crystal of the only one layer of atomic thickness being made up of carbon atom, and its lattice is former by six carbon
The hexagon that son surrounds.Graphene is known, the thinnest, the hardest nano material, and its surface area is big, and light weight is led
The most fabulous, there is good pliability and corrosion resistance so that it is can be combined with other materials as base material, this
Being combined as base material is nanocrystalline with CoO by Graphene in invention, nanocrystalline can being highly dispersed of CoO is grown in stone
On the two-dimensional slice of ink alkene.
Reality prepare this cobalt protoxide nanocrystalline-graphene composite material time, first graphite oxide can be joined N-
In methyl pyrrolidone and carry out dispersion process, obtain mixed liquor.Concrete, N-Methyl pyrrolidone and the ratio of graphite oxide
Can be 1L:1g.This dispersion processes can use the dispersing mode such as ultrasonic disperse, mechanical agitation dispersion process, the most ultrasonic
Dispersion processes.When this mixed liquor does not exist float, when obtaining the brown mixed solution of color even, this mixed liquor is described
It is dispersed through uniformly, just can stop dispersion and process.It should be noted that this dispersion is processed as processing mode commonly used in the art,
Do not illustrate at this.
Needing further exist for explanation, graphite oxide can be buied from market, it is also possible to by existing preparation method system
, those skilled in the art can select according to actual needs, is not specifically limited at this.Oxygen used in the present invention
Graphite is prepared by the Hummers method of following improvement, and the graphite oxide degree of oxidation using the method to prepare is high, dispersion effect
The best, more conducively cobalt protoxide nanocrystalline-preparation of graphene composite material.
Concrete preparation method is as follows:
Weigh 2.5g graphite powder, 2.5g sodium nitrate and 115mL concentrated sulphuric acid, be placed in ice-water bath, under stirring slowly
Add 15g KMnO4；After about 15 minutes, remove ice-water bath, put in 35 DEG C of water-baths, be slowly added to 230mL distilled water, product
Brown is become from black；It is then placed in 98 DEG C of oil baths, after being incubated 15 minutes, removes oil bath, add 700mL warm water, stir shape
Adding 50mL hydrogen peroxide under state, product becomes golden yellow；After product is carried out filtration treatment, with mass percent be 5% dilute
HCl solution washs, then with distilled water wash 5-10 time, until in filtrate without SO4 2-Till；By products therefrom in 70 DEG C of drying baker
In be dried process, obtain graphite oxide.
After obtaining above-mentioned finely dispersed mixed liquor, acetylacetone cobalt and 18-amine. are added to this mixed liquor,
Under stirring, this mixed liquor is heated to 120-140 DEG C, is incubated more than 30 minutes, then proceedes under stirring, heating
To 190-202 DEG C, it is incubated more than 2 hours.Concrete, acetylacetone cobalt and graphite oxide ratio can be 1mol:(20-40) g,
It is preferably 1mol:20g.Graphite oxide can be 1:(12.5-50 with the mass ratio of 18-amine .), preferably 1:12.5.
Wherein, 18-amine., as confinement agent, on the one hand is used for preventing the nanocrystalline growth of CoO uneven, advantageously forms list
Scattered CoO is nanocrystalline, and on the other hand, 18-amine., as a kind of reducing agent, can avoid Co3+Generation, reduction-oxidation simultaneously
Graphite is the generation of Graphene, beneficially composite.Inventor finds when the mass ratio of graphite oxide and 18-amine. is 1:12.5
More economical effectively, the beneficially generation of composite.
This mixed liquor is heated to 120-140 DEG C, is incubated more than 30 minutes, the nanocrystalline nucleation of CoO can be made and grow, can
To be understood by, temperature retention time is the longest, and the effect of the nanocrystalline nucleation of CoO and growth is the best, but temperature retention time is long not only can
Make preparation efficiency reduce, also can increase the cost preparing composite.Inventor finds this mixed liquor is heated to 120 DEG C, protects
When warm 30 minutes, preparation efficiency is high and cost is relatively low, is therefore preferably and this mixed liquor is heated to 120 DEG C, be incubated 30 minutes.
Further, carry out heating under stirring and isothermal holding can make acetylacetone cobalt, graphite oxide and ten
It is more uniform that eight amine mix in N-Methyl pyrrolidone, and then makes reaction more uniform, the beneficially generation of composite.
Preferably, this stirring can be magnetic agitation state.Can certainly be other alr modes, as long as not affecting composite wood
Material generation and can reach stir purpose, be not specifically limited at this.
In like manner, after above-mentioned isothermal holding, in order to provide favorable environment for growth nanocrystalline for CoO further, permissible
Continue under stirring, be heated to 190-202 DEG C, be incubated more than 2 hours.In view of preparation efficiency and the requirement of cost, excellent
Elect as and be heated to 202 DEG C (boiling point of N-Methyl pyrrolidone is 202 DEG C), be incubated 2 hours.This stirring can also be magnetic force
Stirring, naturally it is also possible to for other alr modes, as long as not affecting the generation of composite and can reaching to stir purpose
, it is not specifically limited at this.
Nanocrystalline in order to prepare the CoO of size uniform, can stop sudden for reaction after above-mentioned second time isothermal holding.
Specifically mixed liquor can be made to lower the temperature rapidly after adding organic solvent in the way of using addition organic solvent, and then will reaction
Sudden stopping, this organic solvent is preferably ethanol.
After sudden for reaction stopping, needing to carry out separating treatment, cobalt protoxide that will be prepared is nanocrystalline-Graphene composite wood
Material is separated with mixed liquor, can be centrifuged or the mode such as filtration carries out separating treatment, preferably centrifugation to use.Separation is produced
After thing, product normal hexane and acetone can be carried out alternately carrying out washing treatment, then be dried process, obtain cobalt protoxide and receive
Meter Jing-graphene composite material.For washing times, can be selected according to actual product situation by those skilled in the art
Select, such as, can be 3 times or 4 times, be not specifically limited at this.In 40 DEG C, product can be carried out vacuum for dried to do
Dry process, naturally it is also possible to use other dried mode, be not specifically limited at this.
Present invention also offers the cobalt protoxide prepared by said method nanocrystalline-graphene composite material is for being catalyzed neck
The purposes in territory.
It should be noted that above-mentioned dispersion, stir, be centrifuged, filter, wash and dried is place commonly used in the art
Reason method, those skilled in the art can prepare situation according to reality and operate, are not specifically limited at this and illustrate.
Need further exist for explanation, raw material used in preparing this composite material, all can be commercially
Buy or make by oneself, be not specifically limited at this.
Below in conjunction with the embodiment of the present invention, the technical scheme in the embodiment of the present invention is described, it is clear that described
Embodiment be only a part of embodiment of the present invention rather than whole embodiments.Based on the embodiment in the present invention, ability
The every other embodiment that territory those of ordinary skill is obtained under not making creative work premise, broadly falls into the present invention and protects
The scope protected.
Embodiment 1
40mg graphite oxide (GO) is joined in 40mL N-Methyl pyrrolidone, after carrying out ultrasonic disperse about 2 hours,
Obtain finely dispersed brown mixture；
By 2mmol acetylacetone cobalt (Co (acac)2) and 0.5g 18-amine. add in above-mentioned brown mixture, at magnetic force
Being heated to 120 DEG C under stirring, be incubated 30 minutes, then proceed to be heated under magnetic agitation state 202 DEG C, insulation 2 is little
Time；
Add 20mL ethanol to stop sudden for reaction, be then centrifuged process, isolate product, and with normal hexane, third
After ketone alternately washs 3 times, product is vacuum dried in 40 DEG C.
Embodiment 2
40mg graphite oxide (GO) is joined in 40mL N-Methyl pyrrolidone, after carrying out ultrasonic disperse about 2 hours,
Obtain finely dispersed brown mixture；
By 1mmol acetylacetone cobalt (Co (acac)2) and 1.4g 18-amine. add in above-mentioned brown mixture, at magnetic force
Being heated to 125 DEG C under stirring, be incubated 40 minutes, then proceed to be heated under magnetic agitation state 190 DEG C, insulation 3 is little
Time；
Add 20mL ethanol to stop sudden for reaction, be then centrifuged process, isolate product, and with normal hexane, third
After ketone alternately washs 4 times, product is vacuum dried in 40 DEG C.
Embodiment 3
30mg graphite oxide (GO) is joined in 30mL N-Methyl pyrrolidone, after carrying out ultrasonic disperse about 2 hours,
Obtain finely dispersed brown mixture；
By 1mmol acetylacetone cobalt (Co (acac)2) and 1.5g 18-amine. add in above-mentioned brown mixture, at magnetic force
Being heated to 140 DEG C under stirring, be incubated 60 minutes, then proceed to be heated under magnetic agitation state 195 DEG C, insulation 4 is little
Time；
Add 20mL ethanol to stop sudden for reaction, be then centrifuged process, isolate product, and with normal hexane, third
After ketone alternately washs 5 times, product is vacuum dried in 40 DEG C.
Characterize and analyze
1, X-ray diffraction (X-ray Diffraction, XRD) is analyzed
The x-ray powder diffraction instrument (model: X Pert PRO MPD) using PAN alytical company of Holland to produce is right
Graphene (GN) used by graphite oxide (GO) prepared by the present invention, the present invention and the cobalt protoxide of the embodiment of the present invention 1 preparation
Nanocrystalline-graphene composite material carries out characterizing the XRD figure recorded as shown in Figure 1.
In Fig. 1, (a) is the XRD figure that the present invention prepares graphite oxide, as seen from the figure, obtains by aoxidizing graphite
The interlamellar spacing of GO be(original graphite is about), there is a typical diffraction in 2 positions, θ=10.8 ° simultaneously
Peak, and the typical diffractive peak of original graphite (2 θ=26.5 °) disappear, and illustrate that the GO obtained effectively is aoxidized.
In Fig. 1, (b) is the XRD figure of the Graphene used by the present invention, as seen from the figure, occurs in that in the range of 2 θ=20-30 °
One obvious diffraction corona, has a weak diffraction maximum, respectively (002) and (100) face of correspondence GN simultaneously in 2 θ=43.2 °,
Show that amorphous carbon exists, and GO is reduced to GN.
In Fig. 1 (c) be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-XRD figure of graphene composite material, by
Scheme visible, cobalt protoxide prepared by the embodiment of the present invention is nanocrystalline-diffraction peak of graphene composite material in 2 θ=36.5 °,
42.4 °, 61.6 °, 73.5 ° and 77.0 °, by with the standard card comparison that PDF card number is 48-1719, it was demonstrated that acquisition be
CoO.Indexing understands further, and it is brilliant that the diffraction maximum of sample corresponds respectively to (111), (200), (220), (311) and (222)
Face, interlamellar spacing is respectively 0.246,0.213,0.150,0.128 and 0.123nm, and corresponding face-centred cubic structure, space group is
Fm3m.Meanwhile, the cobalt protoxide prepared in the embodiment of the present invention is nanocrystalline-graphene composite material in, the diffraction maximum of GO disappears,
Proving to there is not GO, it is relevant that this may be reduced into unbodied GN with GO.Cobalt protoxide prepared by the embodiment of the present invention is received
The XRD diffraction maximum of meter Jing-graphene composite material is significantly broadened, thus it is speculated that the nanocrystalline size of CoO obtained is less.
2, x-ray photoelectron power spectrum (X-ray Photoelectron Spectroscopy, XPS) is analyzed
Use XPS spectrum instrument (model: ESCALAB 250Xi) cobalt protoxide prepared by the embodiment of the present invention 1 nanocrystalline-
The surface composition of graphene composite material and the valence state of cobalt carry out characterizing the XPS spectrum figure recorded as shown in Figure 2.
In Fig. 2 (a) be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-XPS of the C1s of graphene composite material
Collection of illustrative plates.For material with carbon element, general 288.9,287.7,286.0 and 284.7eV the most corresponding O=C-O, C=O, O-C-O and C-
The combination energy of C.From in Fig. 2 (a), cobalt protoxide nanocrystalline-graphene composite material in, peak corresponding for 288.9eV disappears
Losing, 287.7 and about 286.0eV corresponding peaks weaken, and cobalt protoxide that i.e. prepared by the embodiment of the present invention is nanocrystalline-and Graphene is multiple
Condensation material is practically free of O=C-O functional group, and the content of O=C and O-C-O is little, mainly exists with C-C structure.Show this
Cobalt protoxide prepared by inventive embodiments is nanocrystalline-graphene composite material in, oxygen-containing functional group is reduced effectively.
In Fig. 2 (b) be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-the Co 2p of graphene composite material
XPS spectrum figure.Peak corresponding near 780.72eV in figure belongs to the 2p of cobalt3/2Peak, corresponding defending near simultaneous 786.10eV
Star peak (satellite peak).Peak corresponding near 796.75eV belongs to the 2p of cobalt1/2Peak, simultaneous 802.69eV is attached
Near corresponding satellites.The Δ E i.e. 2p of cobalt can be differed from it can be seen that combine3/2The combination energy 796.75eV that peak is corresponding,
2p with cobalt1/2The difference of the combination energy 780.72eV that peak is corresponding is 16.03eV.Owing to when Δ E is 16eV, being shown to be bivalence
Cobalt (CoO)；When Δ E is 15eV, it is shown to be the cobalt (Co of trivalent2O3)；When Δ E is 15.2eV, it is shown to be bivalence and trivalent
The mixed valence of cobalt, such as Co3O4, so cobalt protoxide prepared by the embodiment of the present invention nanocrystalline-graphene composite material in
Obtain is bivalence cobalt, i.e. CoO, does not contains trivalent cobalt.Meanwhile, near 778.10eV, there is no the peak of correspondence, show the present invention
Cobalt protoxide prepared by embodiment is nanocrystalline-graphene composite material in do not contain metal Co simple substance.XPS spectrum data and XRD
Data consistent, show cobalt protoxide nanocrystalline-graphene composite material can by method provided by the present invention prepare.
3, electron microscopy image analysis
In Fig. 3, (a) is scanning electron microscope (the Scanning Electron using Hitachi company
Microscope, SEM, model: S-4800, accelerating potential: 5kV) to the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-
Graphene composite material carries out characterizing the SEM figure recorded.As seen from the figure, large stretch of graphene-supported tiny CoO is nanocrystalline,
CoO is nanocrystalline to be uniformly dispersed on graphene sheet layer, illustrates that the preparation method provided by the present invention can be prepared on a large scale
Go out cobalt protoxide nanocrystalline-graphene composite material.
In Fig. 3 (b)-(d) be use transmission electron microscope cobalt protoxide prepared by the embodiment of the present invention 1 nanocrystalline-
Graphene composite material carry out characterizing record transmission electron microscope (Transmission Electron Microscope,
TEM) figure.From Fig. 3 (b) and (c) it can be seen that the cobalt protoxide prepared of the embodiment of the present invention nanocrystalline-Graphene composite wood
CoO in material is nanocrystalline for spheroidal particle, is distributed on the lamella of Graphene CoO nanocrystalline high-density, single dispersing.In Fig. 3
C figure that () upper right corner is inserted is the particle diameter chi nanocrystalline for CoO counted according to the particle diameter nanocrystalline for CoO in multiple TEM figures
Very little scattergram, it can be seen in the figure that the nanocrystalline particle diameter of CoO is about 1-6nm, preferably 1.5-4.5nm, mean diameter is about
3nm.From 3, (d) is it will be clear that the edge of Graphene, almost without the superposition phenomenon of graphene sheet layer, invention is described
Cobalt protoxide prepared by embodiment is nanocrystalline-graphene composite material in Graphene the thinnest, and there is no agglomeration.Meanwhile,
CoO is nanocrystalline to be grown on graphene sheet layer firmly.
In Fig. 3, (e) and (f) is for using high resolution electron microscope (High Resolution Transmission
Electron Microscopy, HRTEM, model: JEM-2010, accelerating potential: 200kV) to the embodiment of the present invention 1 preparation
Cobalt protoxide is nanocrystalline-and graphene composite material carries out characterizing the HRTEM figure recorded.From Fig. 3, (e) can significantly more see
The edge of Graphene, almost without the superposition of graphene sheet layer, again demonstrates cobalt protoxide nanometer prepared by inventive embodiments
Graphene in crystalline substance-graphene composite material is the thinnest, and does not has agglomeration, and nanoparticle is grown in graphene sheet layer firmly
On.From Fig. 3, (f) can be seen that the nanocrystalline lattice clearly of CoO, and its spacing of lattice is 0.213nm, with (200) crystal face of CoO
Correspondence, illustrates that the CoO of Emission in Cubic is nanocrystalline and grows along (200) crystal face.
In Fig. 3 (g) be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-Selected area electron of graphene composite material
Diffraction (Selected Area Electron Diffraction, SAED) figure, from Fig. 3, (g) is it can be seen that the present invention implements
Cobalt protoxide prepared by example is nanocrystalline-and graphene composite material has three rings clearly, learnt by calculating, respectively correspondence
(111), (200), (220) and (311) crystal face nanocrystalline for CoO, consistent with XRD and XPS data.(wherein (222) crystal face is very
Weak, do not show.)
4, absorbing property result
For the assessment cobalt protoxide prepared of the embodiment of the present invention nanocrystalline-microwave absorbing property of graphene composite material,
Cobalt protoxide prepared by the embodiment of the present invention 1 is nanocrystalline-and graphene composite material uniformly mixes (the embodiment of the present invention with paraffin
The cobalt protoxide of 1 preparation is nanocrystalline-and graphene composite material mass percent in the mixture is 60%, and paraffin does not has electromagnetism
Ripple absorbent properties), it is assembled into an electro-magnetic wave absorption device, the external diameter of this device and internal diameter are 7.00nm and 3.04nm respectively,
Agilent E8362B vector network analyzer is used to characterize.Test is carried out, instead under fixing frequency and thickness of sample
Penetrating loss value (RL) to calculate according to microwave transmission theory, formula is as follows:
RL (dB)=20log | (Zin-Z0)/(Zin+Z0)|
Wherein, ZinFor input impedance, Z0For air impedance, μrFor relative permeability, εrFor relative dielectric constant, f is microwave
Frequency, d is thickness of sample, and c is the light velocity.
Fig. 4 be the cobalt protoxide of the embodiment of the present invention 1 preparation recorded by above-mentioned electro-magnetic wave absorption device nanocrystalline-stone
The microwave reflection rate loss value of ink alkene composite and the graph of a relation of thickness of sample.At 1.0-18.0GHz frequency range build-in test
The reflection loss value of different thickness of sample is with the variation relation of frequency.When the reflection loss value of absorbing material is-10dB, table
Showing that the electromagnetic wave of 90% is absorbed, the electromagnetic wave of only 10% is reflected, and this absorbing material is considered to have actual application value.
As seen from Figure 4, along with the increase of thickness of sample, occur that the adsorption frequency of minimal losses value moves to low frequency, absorption intensity simultaneously
Increasing, absorption band increases.By regulating the thickness of sample, sample is at low frequency (1-6GHz), intermediate frequency (7-12GHz) and high frequency (13-
Reflection loss value 18GHz) all can be less than-10dB.
Concrete, it can be seen from figure 4 that when thickness of sample is 2mm, absorbs the most by force and occur in 15.0GHz, reflection is damaged
Consumption value is-8.9dB；When thickness of sample is 3mm, absorbing the most by force and occur in 9.5GHz, reflection loss value is-11.0dB；Work as sample
When product thickness is 4mm, absorbing the most by force and occur in 6.9GHz, reflection loss value is-11.8dB；When thickness of sample is more than 4mm, go out
Existing two absworption peaks the strongest, when being 5mm such as thickness of sample, are absorbed as the most by force 5.2GHz, and reflection loss value is-13.1dB, and
17.6GHz, reflection loss value is-22.7dB；When thickness of sample is 6mm, it being absorbed as the most by force 4.1GHz, reflection loss value is-
16.3dB, and 14.6GHz, reflection loss value is-20.6dB；When thickness of sample is 7mm, it is absorbed as the most by force 2.8GHz, reflection
Loss value is-24.0dB, and 10.6GHz, and reflection loss value is-19.5dB.Minimal reflection loss value is
During 9mm, frequency is to reach-31.1dB during 2.3GHz.Meanwhile, when thickness of sample is 9mm, three effective absworption peak (RL occur
<-10dB), respectively appear in low frequency 2.3GHz, reflection loss value is-31.1dB, intermediate frequency 9.2GHz, reflection loss value is-
15.7dB and high frequency 16.3GHz, reflection loss value is-13.6dB, i.e. thickness of sample is to be attained by all band during 9mm
Effect absorbs.
It is known that when the reflection loss value of absorbing material is less than-10dB, such absorbing material just has reality
Using value, thus cobalt protoxide prepared by the embodiment of the present invention nanocrystalline-graphene composite material have excellence wave absorbtion
Can, actual application value can be reached.It addition, along with the increase of absorbent thickness, its absorption intensity increases, and absorption band to
Low frequency moves.By regulating the thickness of sample, reflection loss can cover 1-18GHz frequency band, it was demonstrated that prepared by the embodiment of the present invention
Cobalt protoxide nanocrystalline-graphene composite material can by regulation thickness reach all band absorb actual application valency
Value.
5, magnetic property result
The magnetization curve test instrunment (model: MPMS-s-SQUID) using Quantum Design company of the U.S. to produce exists
Magnetic field intensity be under the conditions of 100Oe to the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-graphene composite material carries out table
Levy the graph of a relation of the intensity of magnetization and the temperature recorded as shown in Figure 5.Wherein, M represents that the intensity of magnetization, T represent kelvin degree.
In Fig. 5 (a) be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-null field of graphene composite material is cold
(ZFC) magnetization curve, in Fig. 5 (b) be the cobalt protoxide of the embodiment of the present invention 1 preparation nanocrystalline-field of graphene composite material
Cold (FC) magnetization curve.As seen from Figure 5, the cobalt protoxide that prepared by the embodiment of the present invention is nanocrystalline-and graphene composite material is zero
During field cooling is measured, temperature is almost nil more than intensity of magnetization during 0K.And during having field cooling to measure, temperature is big
The intensity of magnetization when 0K is not zero, and shows magnetic.And the cobalt protoxide that as can be seen from Figure 5 prepared by the embodiment of the present invention receives
Meter Jing-graphene composite material does not has hysteresis, and therefore, cobalt protoxide prepared by the embodiment of the present invention is nanocrystalline-Graphene
Composite material exhibits has gone out superparamagnetism.
6, catalytic performance result
Use linear sweep voltammetry test instrunment (model: Zahner IM6) at CO2Real to the present invention with in Ar atmosphere
The cobalt protoxide of executing example 1 preparation is nanocrystalline-and graphene composite material carries out characterizing the catalysis CO recorded2Electric current density and current potential
Graph of a relation as shown in Figure 6.
As seen from the figure, at CO2Electric current density absolute value corresponding in atmosphere is significantly greater than electric current corresponding in Ar atmosphere
Density absolute value, this be due to electrolysis water while also at electroreduction CO2, so electric current density absolute value can only exist by ratio
The electric current density absolute value being electrolysed water in Ar atmosphere is bigger.Typically, reduction CO2The suddenly required current potential of rate determining step be the highest
, for-1.2V, this is also reduction CO in prior art2A maximum bottleneck.It can be seen that it is real with the present invention
Execute cobalt protoxide prepared by example nanocrystalline-graphene composite material as catalyst, by CO2Reduction potential be reduced to-
0.7V.And, along with current potential continues to raise, electric current density absolute value continues to increase, and shows oxidation prepared by the embodiment of the present invention
Sub-cobalt nanocrystal-graphene composite material is as catalyst, to CO2Electro-catalysis reduction has extraordinary catalytic performance.
Visible, with Graphene as substrate in this programme, by thermal decomposition method one step reduction obtain cobalt protoxide nanocrystalline-stone
Ink alkene composite, without Co in this composite3O4Or simple substance Co, has obtained pure CoO, and the nanocrystalline dispersion of CoO is equal
Even, soilless sticking phenomenon, so that this composite is while having good absorbing property and magnetic property so that it is catalytic performance
Obtain the biggest improvement.
Above to cobalt protoxide provided by the present invention nanocrystalline-graphene composite material, its preparation method and apply into
Go and be discussed in detail.Principle and the embodiment of the present invention are set forth by specific embodiment used herein, above reality
The explanation executing example is only intended to help to understand method and the central idea thereof of the present invention.It should be pointed out that, for this area is common
For technical staff, under the premise without departing from the principles of the invention, it is also possible to the present invention is carried out some improvement and modification, these
Improve and modify the protection domain also falling into the claims in the present invention.
Claims (9)
1. a cobalt protoxide nanocrystalline-graphene composite material, it is characterised in that described Graphene in the form of sheets, and described oxygen
Change sub-cobalt nanocrystal to be dispersed on described Graphene.
2. composite as claimed in claim 1, it is characterised in that described cobalt protoxide is nanocrystalline for face-centred cubic structure.
3. composite as claimed in claim 1, it is characterised in that the nanocrystalline particle diameter of described cobalt protoxide is 1-6nm, flat
All particle diameters are 3nm.
4. the preparation method of the composite as described in any one of claim 1-3, it is characterised in that including:
Graphite oxide joined in N-Methyl pyrrolidone and carry out dispersion process, obtaining mixed liquor；
Acetylacetone cobalt and 18-amine. are added to described mixed liquor, under stirring, described mixed liquor is heated to 120-
140 DEG C, it is incubated more than 30 minutes, then proceedes to, under stirring, be heated to 190-202 DEG C, be incubated more than 2 hours；
Add organic solvent to stop sudden for reaction, isolate product, and described product is washed and dried；
Wherein, described acetylacetone cobalt and described graphite oxide ratio are 1mol:(20-40) g, described graphite oxide and described ten
The mass ratio of eight amine is 1:(12.5-50), described N-Methyl pyrrolidone is 1L:1g with the ratio of described graphite oxide.
5. preparation method as claimed in claim 4, it is characterised in that described dispersion is processed as ultrasonic disperse and processes.
6. preparation method as claimed in claim 4, it is characterised in that described in be heated to 190-202 DEG C, particularly as follows: be heated to
202℃。
7. preparation method as claimed in claim 4, it is characterised in that described organic solvent is ethanol.
8. preparation method as claimed in claim 4, it is characterised in that described carrying out washing treatment is: carry out with normal hexane and acetone
Alternately carrying out washing treatment.
9. the composite as described in any one of claim 1-3 is in the application of catalytic field.
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