Flake nano β-cobalt hydroxide is prepared using liquid phase cathode glow discharging plasma
Method
Technical field
The invention belongs to technical field of nanometer material preparation, are related to a kind of flake nanoβ-Co(OH)2Preparation method, it is special
It is not related to a kind of directly preparing flake nano by positive C o piece using liquid phase cathode glow discharging plasma techniqueβ-Co(OH)2
Method.
Background technique
Co(OH)2It is to prepare one of critical materials of rechargeable batteries such as Ni-Cd, MH-Ni and lithium ion.As battery
Additive, Co (OH)2The charge-discharge performance that battery can be significantly improved, improves the electric conductivity and charge efficiency of electrode, and extension is filled
Discharge cycles service life and the utilization rate of active material etc..In addition, Co (OH)2And prepare anode material for lithium-ion batteries LiCoO2
Excellent presoma;Meanwhile Co (OH)2Still the raw material of cobalt compound are prepared.Therefore, with the industry of China's high-energy battery
Fast development, market is to Co (OH)2Demand increasingly increase that (Xu Qiuhong waits application chemical industry, 2006,35 (7): 504).
Co(OH)2There are mainly two types of structures, respectivelyαWithβType.β-Co(OH)2Withβ-Ni(OH)2Structure it is similar, be
Hexagonal crystal system (CdI2Type).Co(OH)2The nanosizing of particle is to realize the basis of its excellent chemical property.β-Co(OH)2System
Preparation Method mainly has precipitation transformation method, inert gas shielding method, electrolysis method and solid reaction process etc..Xie Ming etc. (power technology,
1998,22 (4): it 148) is prepared by electrolysis-precipitation methodβ-Co(OH)2.Li Yangxing etc. (power technology, 1999,23
(6): 325) by preparing under inert gas protectionβ-Co(OH)2Platelet fine powder.Wang Wendi etc. (process engineering journal,
2006,6 (1): it 128) is examined under condition of different pH using hydro-thermal methodβ-Co(OH)2Nanocrystalline synthesis and performance.Merchant
Hall gives etc. that (2005,21 (4): Chinese Journal of Inorganic Chemistry 535) is synthesized with solid reaction processβ-Co(OH)2Nanometer rods.So
And at Co (OH)2Preparation process can encounter many difficulties, Co (OH)2Colloid easy to form is difficult to filter when precipitating;It is in alkali
Property solution in be easy by the dioxygen oxidation in air be sepia Co (OH)3Deng.Although above-mentioned preparation method is preventing Co
(OH)2Colloid forms aspect and obtains certain achievement, but inert gas method is still used in terms of preventing oxidation.This certainly will be to technique item
Part and production equipment propose higher requirement, not only make that the production cost increases, and are difficult in the subsequent handlings such as being filtered, washed
Avoid product not oxidized.Due to severe reaction conditions, Co (OH)2Industrialized production difficulty larger (Xu Qiuhong waits to answer
With chemical industry, 2006,35 (7): 504).In addition, Co (OH)2Preparation process in, be with Co (NO3)2·6H2O、CoSO4Etc. for
Cobalt salt presoma reacts under inert gas protection using ammonia spirit as precipitating reagent, and process is complicated, expensive, is also easy to produce two
Secondary pollution.
Liquid phase cathode glow discharging is a kind of electrochemical method of novel non-equilibrium low temperature plasma of generation.Common electricity
In solution preocess, if cobalt piece anode and platinum needle point cathode are inserted into electrolyte solution simultaneously, and apply certain direct current
After pressure, the liquid water around cathode is breakdown, generates ultraviolet light and high activity particle such as HO, H, O, HO2And H2O2, these
Active particle can cause many solution chemistry reactions, as material surface modifies (Joshi R, et al, Plasma Chem.
Plasma Process., 2013,33:291), prepare high-performance polymer (Yu J, et al. Colloid Polym
Sci, 2016,294:1585), organic wastewater degraded (Zheng Jidong etc., ACTA Scientiae Circumstantiae, 2017,37 (6): 2164)
Deng.However, up to the present, preparing nanometer with liquid phase cathode glow discharging plasma techniqueβ-Co(OH)2Research it is domestic
It yet there are no document report outside.
Summary of the invention
The purpose of the present invention is be directed to existing nanometerβ-Co(OH)2Preparation process it is complicated, condition is harsh, production cost is inclined
The defects of high, provides a kind of convenient, fast synthesis nanometerβ-Co(OH)2Method --- utilize the liquid phase negative glow of sacrificial anode
Light discharge plasma technique prepares flake nanoβ-Co(OH)2Method.
One, flake nanoβ-Co(OH)2Preparation process and device
The present invention prepares flake nano using liquid phase cathode glow discharging plasmaβ-Co(OH)2Method, be with cobalt
Piece (Co) is anode, and needle-shaped platinum filament (Pt) is cathode, 2 ~ 4g/L of concentration NaNO3Solution is electrolyte, and high-voltage DC power supply provides
Electric energy applies 150 ~ 250V voltage between two electrode of yin-yang, and carries out continuing stirring (80 ~ 150r/ of mixing speed to electrolyte
Min), cathode generates aura and forms stable glow discharge plasma, and anode cobalt piece constantly consumes, and solution is from colourless to brown
Transformation;Keep the temperature of electrolyte at 10 ~ 40 DEG C, 0.5 ~ 2.0h of continuous discharge obtains brown turbid;Then brown turbid is surpassed
Sound disperses (10 ~ 15min), and high speed centrifugation (10000 ~ 15000r/min of revolving speed) is first washed with distilled water to remove electrolyte, then
It is washed with dehydrated alcohol, constant weight is then dried under vacuum at 40 ~ 60 DEG C, product is received with agate mortar is finely ground to get to sheet
Riceβ-Co(OH)2。
Positive C o piece is handled by following technique: being impregnated with first after liquid honing, polishing, then existed in acetone respectively
Supersound washing in ethyl alcohol and deionized water, to remove the grease on surface.
Nanometerβ-Co(OH)2Preparation principle: liquid phase cathodic discharge plasma technique i.e. applied voltage effect under, will
Anode metal cobalt piece is oxidized to Co2+, hydrone restored on yin liberation of hydrogen generate OH-, Co2+It moves to cathode glow space and generates Co
(OH)2.Its key reaction is as follows:
Anode: Co → Co2++2e (1)
Cathode: 2H2O+2e →2OH- +H2↑ (2)
Plasma-solution interface: Co2+ +2OH- →Co(OH)2↓ (3)
Overall reaction are as follows: Co+2H2O→Co(OH)2↓+H2 (4)
By controlling discharge voltage, OH in solution can control-And Co2+Generation speed and concentration, to push (4)
Formula carries out to the right, generates Co (OH)2Crystal grain and nucleation and growth process.Due to having H in solution2It generates, therefore can prevent to generate in solution
Co(OH)2It is oxidized to Co (OH)3。
Two, nanometerβ-Co(OH)2Characterization
Below by, come to illustrate discharge process not be common electrolytic process, passing through measurement to current -voltage curve analysis
PH value of solution explains reaction mechanism, is carried out using infrared spectroscopy, X-ray powder diffraction, scanning electron microscope to the structure and pattern of material
Characterization.
1, current -voltage curve
With LW100J2 DC current regulator power supply (0 ~ 1000 V of voltage, the electric current 0 of Shanghai Li You Electrical Appliances Co., Ltd
~ 1 A) electric current under different voltages is measured.Fig. 1 is that anode cobalt piece is placed in 2g/L NaNO3For electrolyte, by adjusting not
Same voltage, the current -voltage curve of the discharge plasma of drafting.As shown in Figure 1, entire discharge process be divided into three sections it is whole: 0 ~
100V sections, Current Voltage variation is in moderate tone, and general electrolytic occurs;100 ~ 140V sections, with the increase of voltage, current fluctuation compared with
It is high.When more than 140V, glow discharge is generated, continues to increase voltage, electric current increases with it, aura enhancing.Due to preparing nanometerβ-
Co(OH)2Voltage range of choice be 150 ~ 250V, therefore belong to plasma discharging Antibody Production Techniques.
2, it preparesβ-Co(OH)2The variation of pH value of solution in the process
Using anode as cobalt piece, under 200V discharge voltage, determines solution ph in discharge process and changes with time relationship,
As a result see Fig. 2.It can be seen that neutrality is presented in the pH of system before starting, after electric discharge starts, the pH value of solution increases sharply, and solution is in
It is now alkalinity, pH value of solution is being maintained at 11.0 or so fluctuations later, illustrate that whole process is carried out in alkaline environment, generation
Product is Co (OH)2。
3, infrared test
Using U.S.'s Digilab FTS3000 type Fourier infrared spectrograph in 400 ~ 4000 cm–1Table is carried out to product
Sign, is as a result shown in Fig. 3.It can be seen that 3631 cm–1Place corresponds to Co (OH)2The stretching vibration of middle O-H;3446 and 1646 cm–1
Correspond respectively to the stretching vibration and flexural vibrations peak of absorption water O-H;494cm–1The strong peak at place is attributed to Co (OH)2Middle Co-O
Thus the stretching vibration of key primarily determines that product is Co (OH)2。
4, XRD is tested
The structure of product is tested using Rigaku D/max-2400 type x-ray diffractometer (XRD).Fig. 4 is institute
Obtain the XRD spectrum of product.As seen from the figure, there are 8 apparent diffractive features peaks within the scope of 2 θ=5 ~ 90 °, be located at 2θ=
19.14 °, 32.45 °, 37.98 °, 39.90 °, 57.83 °, 61.45 °, 69.51 ° and 72.04 °, (001) is corresponded respectively to,
(100), (101), (102), (110), (111), (103) and (201) crystallographic plane diffraction peak, by withβ-Co(OH)2Standard x RD
Spectrogram (JCPDS No. 30-0443) control finds that all diffraction peak and standard card peak position coincide preferably, illustrates to prepare
Obtained Co (OH)2For hexagonal system structureβType Co (OH)2, belong to P3The space m1 group.From Fig. 4 it can easily be seen that in spectrogram
Do not occur apparent other impurities diffraction maximum, show that product purity is higher, crystallization degree is good, no miscellaneous phase.In addition, withβ-Co
(OH)2Standard x RD spectrogram (JCPDS No. 30-443) is compared, this 8 diffraction maximums have obviously widthization phenomenon.Due to
Diffraction peaks broadening is one of characteristic of nanoparticle, shows that prepared sample particle diameter is smaller, generates small-size effect, in receiving
Rice magnitude, influences the XRD diffraction maximum of its own.According to Debye-Scherrer formulaD=kλ/(βcosθ) (whereink=0.89,λ
=0.1542nm,βFor half width), it is calculated by the halfwidth of main peak (001) diffraction maximumβ-Co(OH)2Crystallite dimension be about
19.24nm。
5, sem test
Using Japanese JSM-6700F type scanning electron microscope (SEM) to nanometerβ-Co(OH)2It is scanned, to see
Examine the size and pattern of sample.Sample metal spraying after 60 DEG C of vacuum drying before observing.Fig. 5 is nanometerβ-Co(OH)2Scanning electricity
Mirror.From fig. 5, it can be seen that prepared product is mainly in hexagon flat crystal structure, hexagonal flake under different discharge voltages
Size is between 300 ~ 500nm.
The present invention has the advantage that compared with the prior art
1, using liquid phase cathodic discharge plasma, flake nano is made by sacrificial anode cobalt pieceβ-Co(OH)2, can lead to
Regulation concentration of electrolyte, discharge voltage, discharge time etc. are spent, the Co (OH) of different-grain diameter is obtained2Nano particle;
2, it is prepared using liquid phase cathodic discharge plasmaβ-Co(OH)2Nano particle, impurity in products are few, with high purity, brilliant
It spends, good dispersion, convenient for separation, industrialized production can be carried out;
3, simple process, easy to operate, mild condition (room temperature is not necessarily to other gas shields), chemical reagent type is few, uses
Measure it is low, it is without secondary pollution, it is environmentally protective.
Detailed description of the invention
Fig. 1 is the current -voltage curve of liquid phase cathode glow discharging.
Fig. 2 is the variation of pH value of solution in different discharge times.
Fig. 3 is nanometerβ-Co(OH)2Infrared spectroscopy.
Fig. 4 is nanometerβ-Co(OH)2XRD spectrum.
Fig. 5 is the nanometer that the present invention is prepared at different conditionsβ-Co(OH)2SEM pattern (a be 2g/L NaNO3It is molten
Liquid, 120r/min, 150V, 148mA, electric discharge 2.0h;B is the NaNO of 2g/L3Solution, 120r/min, 180V, 178mA, electric discharge
2.0h;C is the NaNO of 2g/L3Solution, 120r/min, 200V, 204mA, 1.5 h of electric discharge;D is the NaNO of 2g/L3Solution, 120r/
Min, 220V, 230 mA, electric discharge 1h).
Fig. 6 is that liquid phase cathode glow discharging of the invention prepares nanometerβ-Co(OH)2Schematic device.
Specific embodiment
Prepared by nanometer to the present invention below by specific embodimentβ-Co(OH)2Device and method be described further.
Embodiment 1
Liquid phase cathode glow discharging plasma device: the reaction vessel 1 including 250mL, the bottom end setting of reaction vessel 1
Have cathodic acicular platinum filament 3(0.5mm, long 1mm, and be sealed in quartz ampoule and expose quartz ampoule 1mm), the top of reaction vessel 1
It is provided with anode cobalt piece 4(long 1.0cm, width 1.0cm, thickness 0.5mm;It is soaked in acetone using preceding with first after liquid honing, polishing
10min is steeped, then the supersound washing 10min in ethyl alcohol and deionized water respectively, to remove the grease on surface.);Cathode platinum filament 3
It is disposed vertically with anode cobalt piece 4, and the spacing of the two is 1.5cm.Anode cobalt piece, cathodic acicular platinum filament are connected by conductor wire respectively
Meet high-voltage DC power supply 5(LW100J2) positive and negative electrode;It is loaded with sodium nitrate electrolyte 2 in reaction vessel 1, and anode cobalt piece 4,
Cathodic acicular platinum filament 3 is dipped in electrolyte;The top of reaction vessel 1 is equipped with sealing cover, has gas discharge outlet 9 on sealing cover.
Water jacket 11 is equipped with outside reaction vessel 1, water jacket is equipped with water inlet 7 and water outlet 8;Constantly into and out of cooling water in water jacket.Reaction
Stirrer 10(is placed in container 1 referring to Fig. 6).
Flake nanoβ-Co(OH)2Preparation process: in reaction vessel 1, be added 200mL concentration be 2.0g/L nitric acid
Sodium solution carries out solution with 120r/min to continue stirring as electrolyte, and is kept for 25 DEG C of temperature.Control the electricity of yin-yang interpolar
Pressing is 150V, electric current 148mA, and cathode generates aura, forms stable glow discharge plasma 6.In discharge process, anode
Cobalt piece constantly consumes, and solution is changed into brown by colourless, after continuous discharge 2.0h, obtains Co (OH)2Turbid.By turbid ultrasound
Disperse 10min, be centrifugated with the revolving speed of 12000r/min, distills water washing, then washed for several times with dehydrated alcohol.45 DEG C of vacuum
Drying is ground to constant weight to get nano Co (OH)2.Its SEM is shown in Fig. 5 a.
Embodiment 2
Liquid phase cathode glow discharging plasma device: with embodiment 1.
Prepare nanometerβ-Co(OH)2Technique: concentration of electrolyte be 2.0g/L sodium nitrate, stirred, put with 120r/min
Piezoelectric voltage is adjusted to 180V, electric current 178mA, discharge time 2h, other are same with embodiment 1.Gained nanometerβ-Co(OH)2SEM
Pattern is shown in Fig. 5 b.
Embodiment 3
Liquid phase cathode glow discharging plasma device: with embodiment 1.
Prepare nanometerβ-Co(OH)2Technique: control voltage 200V, electric current 204 mA, discharge time 1.5h.Other with
Embodiment 1 is same.Gained nanometerβ-Co(OH)2SEM pattern see Fig. 5 c.
Embodiment 4
Liquid phase cathode glow discharging plasma device: with embodiment 1.
Prepare nanometerβ-Co(OH)2Technique: control voltage 220V, electric current 230 mA, discharge time 1h.Other and reality
It is same to apply example 1.Gained nanometerβ-Co(OH)2SEM pattern see Fig. 5 d.
By the SEM pattern of embodiment 1-4 it is found that by changing technological parameter, such as concentration of electrolyte, voltage or electric current
Size, conduction time etc. can obtain the nano material of different structure, different-grain diameter.