CN110208168A - A kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture - Google Patents
A kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture Download PDFInfo
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- CN110208168A CN110208168A CN201910571773.8A CN201910571773A CN110208168A CN 110208168 A CN110208168 A CN 110208168A CN 201910571773 A CN201910571773 A CN 201910571773A CN 110208168 A CN110208168 A CN 110208168A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a kind of transmission electron microscopies of the distributed in three dimensions structure of on-spot study alloy nanoparticle during the sintering process, the carbon nano-fiber by electrostatic spinning technique and heat treatment, after obtaining carbonization treatment；And the precursor salt of alloy is loaded on carbon nano-fiber；Metal needle point is packed into the specimen holder fixing end of transmission electron microscope, carbon nano-fiber loads acupuncture needle platform, and acupuncture needle is loaded on specimen holder movable end；On loading in the specimen holder of metal needle point and acupuncture needle insertion transmission electron microscope, adjust specimen holder movable end acupuncture needle height and position, the carbon nano-fiber on acupuncture needle platform is set to be in contact with metal needle point, and apply certain voltage in certain instantaneous time, make the precursor salt for being supported on carbon nano-fiber on acupuncture needle platform that instantaneous carbon-thermal reduction occur and forms alloy nanoparticle, the observation changes in distribution of alloy nanoparticle and sintering situation under electric current field action；Shooting two-dimensional projection's transmission electron microscope photo is aligned electromicroscopic photograph by software, three-dimensionalreconstruction and visualization processing.
Description
Technical field
The present invention relates to on-spot study multicomponent alloy nanometers under a kind of transmission electron microscopy more particularly to transmission electron microscope
The method of distributed in three dimensions situation of the grain under electric current field action.
Technical background
Fossil energy is always basis for the survival of mankind, supports the rapid development of modern society.It is well known that
Fossil energy belongs to non-renewable energy resources, and the demand with human society to the energy is increasing, and international energy situation is increasingly tight
High, exhaustion and the fossil energy of the energy cause the extensive concern of countries in the world using bring problem of environmental pollution.To solve
The non-renewable two fold problem with environmental pollution of traditional fossil energy bring, demand of the mankind to new energy increasingly increase,
Such as solar energy, nuclear energy, wind energy, tide energy etc. are renewable, sustainable energy has obtained the concern and research of energy research person.Its
In, fuel cell is a kind of high efficient energy sources conversion equipment that chemical energy is directly converted to electric energy, spatter property with higher and
Environment friendly, and its fuel is from a wealth of sources, environmentally friendly, lasting, therefore fuel cell becomes the ideal substitution energy that attracts attention
Source selection.
Currently, the catalyst performance in fuel cell becomes the key link for restricting fuel cell development, fuel electricity is pushed
The core of pond development is to prepare the catalyst with high electrocatalysis characteristic, high-durability and low cost.Wherein, regulation catalysis
The size and ingredient of agent are to obtain the important means with desired catalytic performance catalyst.Much studies have shown that nanocatalyst
There are higher catalysis potentiality than traditional large scale catalyst, especially make when catalyst size reaches Nano grade, be catalyzed
Activity obtains large range of raising.This has benefited from the bigger serface and quantum size effect due to nanoscale catalyst.
The alloy of multicomponent is prepared by other alloying components of the introducing of proper proportion compared to traditional single group member metallic catalyst
Catalyst can efficiently use the synergistic effect between different metal element, and the multicomponent alloy for obtaining more high catalytic performance is urged
Agent, and the usage amount of noble metal can also be reduced to a certain extent, lower catalyst cost.In addition, the carrier material of high quality
Material can also effectively improve the activity and stability of catalyst, while can reduce use cost, increase the catalysis of catalyst
Efficiency.The advanced carbon material such as carbon nanotube, carbon nano-fiber, mesoporous carbon is by its higher corrosion resistance, higher at present
Specific surface area, suitable voidage etc., which become, studies relatively broad carrier material.
The method for preparing loaded catalyst at present mainly has dipping-liquid phase reduction, gas phase reduction process, electrochemical deposition
Method, agglutinating nature yeast etc., but above method all exists that metal catalyst particles are oversized, size is not easy to control, dispersion
The disadvantages of property is poor.For this purpose, the Hu Liangbing professor team of University of Maryland innovatively proposes to utilize the preparation of moment Joule heat method more
Constituent element is carried on the alloy nano catalyst granules of carbon nano-fiber.This method can prepare size in the conjunction of 10 nm or so
Gold nano catalyst particle, remarkable advantage are that alloy nano catalyst particle components are evenly distributed, and most multipotency is prepared together
When the alloying pellet comprising eight constituent elements, make full use of the synergistic effect between metallic element to further increase catalytic performance, break through
Traditional preparation methods can only at most prepare the bottleneck of three component alloys beaded catalysts.It is substantially former based on moment joule thermal method
Reason, we utilize in situ TEM technology, realize in situ observe metal catalyst particles forming process, research electric current,
The influence of voltage, group metamember etc. to its formation mechenism and distribution, current field environment locating for catalyst in analog fuel battery,
The sintering behavior of particle and the distributed in three dimensions situation of particle under electric current field action are studied, in situ to prepare more high catalytic performance
Alloy nano catalyst granules improve theories integration.
Summary of the invention
The purpose of the present invention is to provide the multicomponent conjunctions that on-spot study under a kind of transmission electron microscope is carried on carbon nano-fiber
The method of the distributed in three dimensions situation of sintering phenomenon and particle of the gold nano grain under electric current field action.
For achieving the above object, as follows using technical solution.
A kind of on-spot study is carried on sintering of the multicomponent alloy nano particle of carbon nano-fiber under electric current field action
The transmission electron microscopy of phenomenon and the distributed in three dimensions situation of particle, comprising the following steps:
The method for depending on the multicomponent alloy nano particle of carbon fiber is prepared in situ in transmission electron microscope, comprising the following steps:
Step 1: being heat-treated by electrostatic spinning technique and early period, obtain diameter range receiving after 100-200 nm carbonization treatment
Rice carbon fiber；
Step 2: preparing metal precursor salt solution, the carbon nano-fiber that step 1 is obtained are soaked in precursor salt solution, with
Obtain the carbon nano-fiber that load has precursor salt；
Step 3: taking another diameter is the nickel chromium triangle metal needle of 0.2 ~ 0.25mm, prepares metal needle point by electrochemical polish method,
It is 3 ~ 5 mm that this metal needle point, which is cut into length, is then charged into specimen holder fixing end, makes metal needle point outwardly；
Step 4: taking length and width is respectively that the load of 2 mm and 1 mm has the carbon nano-fiber of precursor salt, is used conductive silver glue
Sticking at and being pressed from both sides flat diameter is about that acupuncture needle is packed into specimen holder movable end on the acupuncture needle platform of 0.25 mm；
Step 5: by the specimen holder insertion transmission electron microscope for loading upper metal needle point and acupuncture needle, it is high to adjust specimen holder movable end acupuncture needle
Degree and position make metal needle point and acupuncture needle be located at sustained height and opposite position；
Step 6: applying by making the carbon nano-fiber on acupuncture needle platform be in contact with metal needle point, and in certain instantaneous time
Certain voltage makes the precursor salt for being supported on carbon nano-fiber on acupuncture needle platform that instantaneous carbon-thermal reduction occur and forms alloy nano
Particle；
Step 7: continuing that metal needle point is kept to contact with carbon nano-fiber after forming alloy nanoparticle, and apply lasting
Smaller current, the observation changes in distribution of alloy nanoparticle and sintering situation under electric current field action；
Step 8: thering is the carbon nano-fiber of alloy nanoparticle to carry out 180 degree rotation load, shoot 1 attachment at interval of 2 degree
The center bright field image of the carbon nano-fiber of alloy nanoparticle, to obtain a series of two-dimensional projection's transmission electricity under different angles
Mirror photo；
Step 9: using reconstruction software by two-dimensional projection's transmission electron microscope photo under a series of different angles obtained in step 8 into
Row alignment, three-dimensionalreconstruction and visualization processing.
Further, step 1 is realized by following methods:
Step 1.1: being fitted into syringe after polypropylene fine (PAN) is mixed according to a certain percentage with dimethylformamide (DMF)；
Step 1.2: receiving to shield the substrate for placing carrying carbon nano-fiber, it is preferable to use copper foil or carbon paper are as substrate；Through
It tests and shows since copper foil intensity is relatively high, it is not high with the associativity of carbon nano-fiber, therefore be easy in spinning and heat treatment process
Phenomena such as middle generation carbon nano-fiber is peeled off or is crimped.
Step 1.3: adjustment receives the relative position of screen with injector, starts spinning process；It, will in substrate after spinning
It will form a piece of PAN nanofiber；
Step 1.4: the PAN nanofiber that spinning obtains being heat-treated: first placing PAN nanofiber under air environment
The pre-oxidation treatment that 5 hours are carried out in 260 DEG C, is then placed on carrying out at carbonization in 2 hours at 800 DEG C under protection of argon gas
Reason, can be obtained carbon nano-fiber.
Further, in step 2, the precursor salt with alloying component is mixed in ethanol solution, obtains presoma second
Alkoxide solution；The carbon nano-fiber obtained after carbonization is soaked in take out after soaking it sufficiently in precursor ethanol salting liquid and is set
Its natural drying is waited in glass dish, can be obtained the carbon nano-fiber that load has precursor salt.
Further, the process of metal needle point is prepared in step 3 by electrochemical polish method are as follows:
Step 3.1: configuration corrosive liquid is fitted into glass container, a plastic stent is placed by glass container；
Step 3.2: the conducting wire of two end connection copper sheets being connected with both ends of power, and the copper sheet being connected with cathode is immersed
In the corrosive liquid of glass container, the copper sheet being connected with anode is fixed on plastic stent, is placed in above corrosive liquid；
Step 3.3: the round metal bars corroded will be needed to put on the i.e. upper plastic sheath of two plastic sheaths and lower plastic sheath, pole one end with admittedly
The copper sheet being scheduled on plastic stent is connected；Expose the crack of 0.5 ~ 1.0 mm between upper plastic sheath and lower plastic sheath；Upper plastics
Set upper side is located on liquid level, and lower plastic sheath lower end is located under pole lower end；
Step 3.4: after the completion of arrangement, opening power supply, adjustment voltage value is 5 ~ 20 V, and corrosion reaction occurs；
Step 3.5: crack is broken among two plastic sheaths, and power supply is closed after falling in corrosive liquid in pole lower end, from corrosion
The pole fallen is taken out in liquid, and plastic sheath is taken out from pole tail portion using tweezers, obtains nano level metal needle point.
Further, step 4 is realized by following methods:
Step 4.1: length and width of being torn on the carbon nano-fiber that load has precursor salt with tweezers are respectively the small of 2 mm and 1 mm
Piece, and an apiculus is formed it into during tearing, to be easy to realize the gold with specimen holder fixing end in transmission electron microscope
Belong to the contact of needle point.
Step 4.2: taking length is about 3 mm, and diameter is about the acupuncture needle of 0.25 mm, using the good advantage of metal ductility,
One section is pressed from both sides to chain-wales that are flat, being about 0.05 mm with one thickness of acquisition using flat nose pliers, so as to will by conductive silver glue
The carbon nano-fiber torn in step 4.1 is securely fixed on platform, makes carbon nano-fiber tip outwardly.
Step 4.3: the acupuncture needle for being stained with carbon nano-fiber is packed into specimen holder movable end.
Further, step 5 is realized by following methods:
Step 5.1: by the specimen holder insertion Electronic Speculum for loading upper metal needle point and acupuncture needle, by adjusting Electronic Speculum Z axis height, making sample
Metal needle point at product bar fixing end is in positive coke-like state.
Further, in step 6:
Step 6.1: by adjusting movable end height, making the office of the carbon nano-fiber on the acupuncture needle for needing to carry out instantaneous carbon-thermal reduction
Portion is in positive coke-like state, and the front and back for adjusting specimen holder movable end makes the part of the carbon nano-fiber in positive coke-like state with left and right
It is contacted with the metal needle point of specimen holder fixing end；
Step 6.2: in certain instantaneous time, applying certain instantaneous voltage, home position observation between fixing end and movable end
With the carbon-thermal reduction process of the nanofiber of metal needle point contact portion on acupuncture needle, the forming process of alloy nanoparticle is observed；
Step 6.3: the nanofiber at other mobile positions, which repeats step 5, contacts it with metal needle point, when by changing instantaneous
Between and instantaneous voltage, observation and research different time and voltage influence that alloy nanoparticle is formed.
Further, in step 7, precursor salt is formed after alloy nanoparticle under instantaneous carbon heat effect, after continuation of insurance
The contact condition for holding carbon nano-fiber and metal needle point applies lesser electric current between specimen holder fixing end and movable end, according to
Situation changes current forms and size, and using pulse current or constant current etc., home position observation is under the continuous action of current field
The distribution and sintering situation of alloy nanoparticle.
Further, step 8 is realized by following methods:
Step 8.1: to prevent from needing first since the unstable of movement causes both ends to bump against by sample in the selection course below
Bar movable end moves away from specimen holder fixing end backward；
Step 8.2: to formed alloy nanoparticle carbon nano-fiber carry out rotary taking before, first pass through specimen holder to axis
Operation moves to the carbon nano-fiber on axis using bit shift compensation, so that it is not generated biggish drift in rotary course, makes
At the deviation visual field；
Step 8.3: after axis, by adjusting Electronic Speculum height Z, so that the carbon nano-fiber is in positive coke-like state, then carry out 180
Degree rotation, the center bright field image of the carbon nano-fiber of an attachment alloy nanoparticle is shot at interval of 2 degree, to obtain a system
Two-dimensional projection's transmission electron microscope photo under column different angle.
Further, in step 9, suitable three-dimensionalreconstruction software is selected, by the same root before and after the electric current field action of acquisition
Carbon nano-fiber obtains nano carbon particle before and after electric current field action after image preprocessing, to axis, reconstruct and visualization processing
True distribution situation.
Furthermore in conjunction with step 7,8 and 9, it can be achieved that the Three-dimensional Gravity of alloy nanoparticle distribution of particles before and after electric current field action
Structure analysis, to obtain influence result of the more detailed current field to particle distribution.
The present invention has the advantages that
1, the formation mechenism for fully understanding alloy nanoparticle is conducive to prepare the alloy nano catalyst of higher performance, passes through
This method home position observation precursor salt can form the process of alloy nanoparticle in transmission electron microscope under moment Joule heat.
2, by changing the instantaneous voltage and conduction time moment that are applied on the carbon fiber of load precursor salt, Ke Yiyan
Different voltages and conduction time are studied carefully to precursor salt in the influence for forming alloy nanoparticle process, thus suitable by selection
Voltage and conduction time obtain the alloy nanoparticle of ideal dimensions and shape.
3, the Electronic Speculum environment of high vacuum can provide the vacuum environment of an anaerobic for instantaneous carbon-thermal reduction in situ, avoid
Oxidation of precursor salt during forming alloy nanoparticle.
4, sintering situation and alloy nano of the alloy nanoparticle on carrier under electric current field action are had studied in situ
Distributed in three dimensions situation of the particle on carbon nano-fiber more intuitively discloses true position of the alloy nanoparticle on carrier
It sets.
Detailed description of the invention
1, Fig. 1 is electrostatic spinning schematic diagram.
2, Fig. 2 is metal precursor salt loading process schematic diagram.
3, Fig. 3 is the schematic diagram of electrochemical erosion method corrosion metal needle point.
4, Fig. 4 is the acupuncture needle schematic diagram for being stained with the carbon nano-fiber of load precursor salt
5, Fig. 5 is the transmission electron microscope picture of acquisition alloy nanoparticle after in situ be powered.
6, Fig. 6 is the transmission electron microscope picture of the alloy nanoparticle obtained under different instantaneous voltages.
7, Fig. 7 is the transmission electron microscope picture of alloy nanoparticle before and after electric field action.
8, Fig. 8 is the transmission electron microscope picture and Three-dimensional Gravity composition of alloy nanoparticle.
Above in each figure: 1 is metering pump, and 2 be injector, and 3 be polymer solution, and 4 be jet port, and 5 be carbon nano-fiber,
6 is receive screen, and 7 be high voltage power supply, and 8 be glassware, and 9 be plastic stent, and 10 copper sheets, 11 be round metal bars, and 12 be upper plastics
Set, 13 be lower plastic sheath, and 14 be conducting wire, and 15 be corrosive liquid, and 16 glass containers, 17 be acupuncture needle platform, and 18 be acupuncture needle.
Specific embodiment
Embodiment 1
On-spot study is carried on the multicomponent alloy nano particle of carbon nano-fiber under electric current field action under transmission electron microscope
The method of sintering phenomenon and the distributed in three dimensions situation of particle, comprising the following steps:
1, for obtain carbon nano-fiber, we using electrostatic spinning method.Illustrate according to electrostatic spinning shown in FIG. 1
Before figure carries out spinning, it is molten that polypropylene fine (PAN) is first mixed to form polymer with dimethylformamide (DMF) according to a certain percentage
It is fitted into injector after liquid.Then the suitable position on the receiving screen of jet port right opposite is placed for carrying carbon nano-fiber
Substrate.It selects copper foil or carbon paper as substrate, but is shown according to experiment experience due to compared to carbon paper, the intensity of copper foil
It is relatively high and weaker with the associativity of carbon fiber, therefore be easy that nano-sized carbon occurs during spinning and Post isothermal treatment
The peeling and curling of fiber, therefore select carbon paper to prepare carbon nano-fiber as substrate in this example.After carbon paper is fixed, adjust
The relative position for receiving screen with injector, can start spinning after the experiment parameters such as suitable voltage are arranged, pass through metering pump control
The amount of injection of polymer solution in injector processed applies voltage by high voltage power supply and carries out spinning.It, can be in carbon paper after spinning
One layer of white PAN nanofiber of upper formation.
To obtain carbon nano-fiber, Post isothermal treatment is carried out to the PAN nanofiber that electrostatic spinning obtains.Heat treatment is main
It is divided into two parts, first part is 260 DEG C of the pre-oxidation treatment carried out in air environment 5 hours.Second part is in argon
Under gas shielded, 2 hours 800 DEG C of carbonization treatments are carried out.Carbon nano-fiber is obtained after the completion of heat treatment.
2, it needs to prepare golden nickel alloy nanoparticles in this example, it is therefore desirable to according to the ratio of 1:1 by AuCl2And NiCl2
It is dissolved in ethanol solution, configuration obtains golden nickel precursor ethanol salting liquid.As shown in Fig. 2, the carbon nano-fiber that carbonization is obtained soaks
It steeps in configured golden nickel precursor ethanol salting liquid, taking-up, which is placed in glassware, after soaking it sufficiently waits its nature
It is dry, it can be obtained the carbon nano-fiber that load has precursor salt.
3, metal needle point corrosion device as shown in Figure 3 is arranged, taking a diameter is that 0.25mm nichrome stick carries out needle point
Corrosion.As shown in figure 3, taking a glass container, suitable corrosive liquid prepared is poured into glass container, and in glass container
Place a plastic stent in side；Different materials uses different corrosive liquids.For nichrome, using perchloric acid 10% and alcohol
90% mixed liquor.The conducting wire of two end connection copper sheets is connected with both ends of power, and the copper sheet being connected with cathode is immersed
In the corrosive liquid of glass container, be fixed on bracket with the copper sheet that is connected of anode, be placed in corrosive liquid top, pay attention to being sure not to make its with
Corrosive liquid is in contact.Nichrome round metal bars are put on into two plastic sheaths (respectively upper plastic sheath and lower plastic sheath), metal
Pole one end is connected with the copper sheet being fixed on bracket.Making to expose between plastic sheath and lower plastic sheath is about the small of 0.5mm
Seam, while upper plastics set upper side is located on liquid level, lower plastic sheath lower end is located under round metal bars lower end, as shown in Figure 3.Benefit
Round metal bars are protected with plastic sheath, makes that electrochemical corrosion reaction occurs at its only intermediate crack, can obtain in this way
Longer thinner metal needle point.
Power supply is opened, is adjusted to suitable voltage value, in the present embodiment, adjustment voltage value is 5 ~ 20 V.To two plastic sheaths
Intermediate crack is broken, and power supply is closed after falling in corrosive liquid in round metal bars lower end, and the gold fallen is taken out from corrosive liquid
Belong to pole, using tweezers gently by plastic protective sleeve from round metal bars tail portion take out (round metal bars gap is known as head, with
The opposite one end of round metal bars gap is known as tail portion).Round metal bars are polished into out length 10 ~ 100 by electrochemical polish method
The needle point of micron, and needle point tip diameter is 5 ~ 500 nm, in order to it can be with lens specimen bar movable end
The operations such as carbon nano-fiber contact energization.
Since the top and the bottom of round metal bars are all protected by plastic sheath, at only intermediate crack and corrosive liquid
It directly contacts and electrochemical corrosion reaction occurs；With the progress of reaction, the metal at intermediate crack is slowly corroded, radius
It gradually becomes smaller；Under lower part metals pole gravity, be corroded region under tension at intermediate crack；When corrosion area half
Diameter is small to arrive certain value, that is, when the pulling force being subject to is greater than the maximum pull that can be born, intermediate corrosion area can be pulled off and form gold
Belong to needle point；In addition, corrosion condition should be paid close attention in corrosion process constantly, after disconnecting from round metal bars are from intermediate crack, at once
Power supply is closed, the round metal bars fallen are taken out from corrosive liquid.
The round metal bars corroded are cut into appropriate length, in the present embodiment, the round metal bars corroded are cut into length
For 3 ~ 5 mm；Outwardly, the other end fills in transmission electron microscope sample bar movable end to metal needle point, tightens screw, and with tweezers gently to
It pulls out outside, confirmatory sample clamping is secured
4, it to enable the carbon nano-fiber that can be realized partial region in Electronic Speculum to contact with metal needle point, needs light with tweezers
Length and width of gently tearing on the carbon nano-fiber that load has precursor salt are respectively the small pieces of 2 mm and 1 mm, are paid attention in the process torn
In make to form apiculus as shown in Figure 4 as far as possible.
Taking length as shown in Figure 4 is about 3 mm, and diameter is about the acupuncture needle of 0.25 mm, utilizes good excellent of metal ductility
One section is pressed from both sides acupuncture needle platform that is flat, being about 0.05 mm with one thickness of acquisition using flat nose pliers, so as to pass through conduction by point
The carbon nano-fiber that elargol tears step above is securely fixed on acupuncture needle platform, pays attention to that carbon nano-fiber should be made when adhesion
Tip is outwardly.
The acupuncture needle for being stained with carbon nano-fiber is packed into specimen holder movable end.
5, it will be loaded in the specimen holder insertion Electronic Speculum at both ends, therefore need to first pass through since fixing end does not have freedom degree
Electronic Speculum Z axis height is adjusted, the metal needle point at fixing end is made to be in positive coke-like state.
It is then picked out in the carbon nano-fiber of large stretch of load precursor salt of movable end and carries out instantaneous carbon-thermal reduction
Appropriate area.It is at positive coke-like state using the height that the freedom degree of movable end adjusts movable end, and adjusts movable end
Front and back and left and right contact it with the metal needle point of fixing end.
The instantaneous voltage for applying certain time between fixing end and movable end, can be observed phenomenon as shown in Figure 5, bear
The precursor salt being loaded on carbon fiber occurs instantaneous carbon-thermal reduction and forms a large amount of alloy nanoparticles.
6, in this example, can be made by mobile movable end the load precursor salt of different zones carbon nano-fiber and
Metal needle point contact, and apply different voltage under different instantaneous times, it may be implemented to carry out different condition in different zones
Under instantaneous carbon-thermal reduction, observation and research different time and voltage influence that alloy nanoparticle is formed, if Fig. 6 is difference
The transmission electron microscope picture of the Nanoalloy particle obtained under instantaneous voltage.
7, in this example, form that alloy nanoparticle is subsequent continuous to be kept in contact to having already passed through carbon-thermal reduction in situ instantaneous
State, and apply the 0.5V pulse voltage of 1000 s at both ends, as shown in fig. 7, under the action of current field, carbon nano-fiber
On alloying pellet occur bulky grain size become larger, the short grained gradually smaller sintering phenomenon of size.Studies have shown that
Sintering phenomenon can occur in the case where working long hours for alloy nano catalyst granules, and the generation of the phenomenon and the stability of catalyst have
It closes, and will cause the active decline of catalyst.
8, golden nickel in this example, is prepared on the carbon fiber that load has precursor salt by instantaneous carbon-thermal reduction in situ
After alloy nanoparticle, by driving specimen holder movable end, specimen holder fixing end is made it away from, to prevent rotating through in the later period
Since the unstable of movement causes both ends to bump against in journey.
The carbon nanocoils studied will be needed to move to rotary shaft using bit shift compensation function by operating to axis for specimen holder
On line, it is made to be unlikely to the phenomenon that generating biggish drift, causing a departure the visual field in rotary course.
After axis, by adjusting Electronic Speculum height Z, the carbon nano-fiber is made to be in positive coke-like state.It is better to obtain
Center spot is entangled using three-level lens isis in this example of contrast, shoots center bright field image.By operating rotation process software, make
The carbon nano-fiber realizes that 180 degree rotates in Electronic Speculum, and the carbon Nanowire of an attachment alloy nanoparticle is shot at interval of 2 degree
The center bright field image of dimension, to obtain a series of two-dimensional projection's transmission electron microscope photo under different angles.Fig. 8 left hand view is a certain
Load has the transmission electron microscope picture of the carbon fiber of alloy nanoparticle under angle.
9, the dimension projection transmission Electronic Speculum under a series of different angles that in this example, selection IMOD software obtains shooting
Photo is pre-processed, to axis and reconstruct.The restructing algorithm selected in this example is compared with based on, general weighting back projection just
Method.Then, the file that reconstruct obtains is subjected to visualization processing with Tomviz software, obtains the three-dimensional as shown in Fig. 8 right part of flg
Reconfigured geometry.True three-dimension space distribution situation of the alloy nanoparticle on nanofiber can be specified by this result,
Overcome the defect that traditional two-dimensional transmission Electronic Speculum projection result lacks thickness information.
Claims (10)
1. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture, it is characterised in that: the nano particle
For the multicomponent alloy nano particle for being carried on carbon nano-fiber, the distributed in three dimensions structure refers to the institute under electric current field action
The distributed in three dimensions structure for stating the sintering process of nano particle, comprises the following steps that
Step 1: by electrostatic spinning technique and heat treatment, obtaining nano-sized carbon of the diameter range after 100-200 nm carbonization treatment
Fiber；
Step 2: preparing metal precursor salt solution, the carbon nano-fiber that step 1 is obtained are soaked in precursor salt solution, with
Obtain the carbon nano-fiber that load has precursor salt；
Step 3: taking a diameter is the nickel chromium triangle metal needle of 0.2 ~ 0.25mm, prepares metal needle point by electrochemical polish method, will
It is 3 ~ 5 mm that metal needle point, which is cut into length, is then charged into the specimen holder fixing end of the transmission electron microscope, makes metal needle point outwardly；
Step 4: taking length and width is respectively that the load of 2 mm and 1 mm has the carbon nano-fiber of precursor salt, is used conductive silver glue
Sticking at and being pressed from both sides flat diameter is about that acupuncture needle is packed into the specimen holder movable end of the transmission electron microscope on the acupuncture needle platform of 0.25 mm；
Step 5: by the specimen holder insertion transmission electron microscope for loading upper metal needle point and acupuncture needle, it is high to adjust specimen holder movable end acupuncture needle
Degree and position make metal needle point and acupuncture needle be located at sustained height and opposite position；
Step 6: applying by making the carbon nano-fiber on acupuncture needle platform be in contact with metal needle point, and in certain instantaneous time
Certain voltage makes the precursor salt for being supported on carbon nano-fiber on acupuncture needle platform that instantaneous carbon-thermal reduction occur and forms alloy nano
Particle；
Step 7: continuing that metal needle point is kept to contact with carbon nano-fiber after forming alloy nanoparticle, and apply lasting small
Electric current, the observation changes in distribution of alloy nanoparticle and sintering situation under electric current field action；
Step 8: thering is the carbon nano-fiber of alloy nanoparticle to carry out 180 degree rotation load, shoot 1 attachment at interval of 2 degree
The center bright field image of the carbon nano-fiber of alloy nanoparticle, to obtain a series of two-dimensional projection's transmission electricity under different angles
Mirror photo；
Step 9: using reconstruction software by two-dimensional projection's transmission electron microscope photo under a series of different angles obtained in step 8 into
Row alignment, three-dimensionalreconstruction and visualization processing.
2. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 1 is realized by following methods:
Step 1.1: being fitted into syringe after polypropylene fine (PAN) is mixed according to a certain percentage with dimethylformamide (DMF)；
Step 1.2: receiving to shield the substrate for placing carrying carbon nano-fiber, using copper foil or carbon paper as substrate；
Step 1.3: adjustment receives the relative position of screen with injector, starts spinning process；It, will shape in substrate after spinning
At a piece of PAN nanofiber；
Step 1.4: the PAN nanofiber that spinning obtains being heat-treated: first placing PAN nanofiber under air environment
The pre-oxidation treatment that 5 hours are carried out in 260 DEG C, is then placed on carrying out at carbonization in 2 hours at 800 DEG C under protection of argon gas
Reason, can be obtained carbon nano-fiber.
3. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, in step 2, the precursor salt with alloying component is mixed in ethanol solution, obtains precursor ethanol salting liquid；It will
The carbon nano-fiber obtained after carbonization is soaked in take out after soaking it sufficiently in precursor ethanol salting liquid and be placed in glass dish
Its natural drying is waited, that is, obtains the carbon nano-fiber that load has precursor salt.
4. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, prepares the process of metal needle point in step 3 by electrochemical polish method are as follows:
Step 3.1: configuration corrosive liquid is fitted into glass container, a plastic stent is placed by glass container；
Step 3.2: the conducting wire of two end connection copper sheets being connected with both ends of power, and the copper sheet being connected with cathode is immersed
In the corrosive liquid of glass container, the copper sheet being connected with anode is fixed on plastic stent, is placed in above corrosive liquid；
Step 3.3: the round metal bars corroded will be needed to put on the i.e. upper plastic sheath of two plastic sheaths and lower plastic sheath, pole one end with admittedly
The copper sheet being scheduled on plastic stent is connected；Expose the crack of 0.5 ~ 1.0 mm between upper plastic sheath and lower plastic sheath；Upper plastics
Set upper side is located on liquid level, and lower plastic sheath lower end is located under pole lower end；
Step 3.4: after the completion of arrangement, opening power supply, adjustment voltage value is 5 ~ 20 V, and corrosion reaction occurs；
Step 3.5: crack is broken among two plastic sheaths, and power supply is closed after falling in corrosive liquid in pole lower end, from corrosion
The pole fallen is taken out in liquid, and plastic sheath is taken out from pole tail portion using tweezers, obtains nano level metal needle point.
5. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 4 is realized by following methods:
Step 4.1: length and width of being torn on the carbon nano-fiber that load has precursor salt with tweezers are respectively the small of 2 mm and 1 mm
Piece, and an apiculus is formed it into during tearing, to be easy to realize the gold with specimen holder fixing end in transmission electron microscope
Belong to the contact of needle point；
Step 4.2: taking length is about 3 mm, and diameter is about the acupuncture needle of 0.25 mm, using the good advantage of metal ductility, is used
One section is pressed from both sides chain-wales that are flat, being about 0.05 mm with one thickness of acquisition by flat nose pliers, so as to pass through conductive silver glue for step
The carbon nano-fiber torn in 4.1 is securely fixed on platform, makes carbon nano-fiber tip outwardly；
Step 4.3: the acupuncture needle for being stained with carbon nano-fiber is packed into specimen holder movable end.
6. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 5 is realized by following methods:
Step 5.1: by the specimen holder insertion Electronic Speculum for loading upper metal needle point and acupuncture needle, by adjusting Electronic Speculum Z axis height, making sample
Metal needle point at product bar fixing end is in positive coke-like state.
7. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 6 is realized by following methods:
Step 6.1: by adjusting movable end height, making the office of the carbon nano-fiber on the acupuncture needle for needing to carry out instantaneous carbon-thermal reduction
Portion is in positive coke-like state, and the front and back for adjusting specimen holder movable end makes the part of the carbon nano-fiber in positive coke-like state with left and right
It is contacted with the metal needle point of specimen holder fixing end；
Step 6.2: in certain instantaneous time, applying certain instantaneous voltage, home position observation between fixing end and movable end
With the carbon-thermal reduction process of the nanofiber of metal needle point contact portion on acupuncture needle, the forming process of alloy nanoparticle is observed；
Step 6.3: the nanofiber at other mobile positions, which repeats step 5, contacts it with metal needle point, when by changing instantaneous
Between and instantaneous voltage, observation and research different time and voltage influence that alloy nanoparticle is formed.
8. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 7 is realized by following methods:
Precursor salt is formed after alloy nanoparticle under instantaneous carbon heat effect, continues to keep carbon nano-fiber and metal needle
The contact condition of point applies low current between specimen holder fixing end and movable end, changes current forms and size, uses pulse electricity
Stream or constant current, the distribution and sintering situation of home position observation alloy nanoparticle under the continuous action of current field.
9. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 8 is realized by following methods:
Step 8.1: to prevent from needing first since the unstable of movement causes both ends to bump against by sample in the selection course below
Bar movable end moves away from specimen holder fixing end backward；
Step 8.2: to formed alloy nanoparticle carbon nano-fiber carry out rotary taking before, first pass through specimen holder to axis
Operation moves to the carbon nano-fiber on axis using bit shift compensation, so that it is not generated biggish drift in rotary course, makes
At the deviation visual field；
Step 8.3: after axis, by adjusting Electronic Speculum height Z, so that the carbon nano-fiber is in positive coke-like state, then carry out 180
Degree rotation, the center bright field image of the carbon nano-fiber of an attachment alloy nanoparticle is shot at interval of 2 degree, to obtain a system
Two-dimensional projection's transmission electron microscope photo under column different angle.
10. a kind of transmission electron microscopy of on-spot study nanoparticle three-dimensional distributed architecture according to claim 1, feature
It is, step 9 is realized by following methods:
Using three-dimensionalreconstruction software, by the same root carbon nano-fiber before and after the electric current field action of acquisition by image preprocessing,
To the true distribution situation for obtaining electric current field action front and back nano carbon particle after axis, reconstruct and visualization processing.
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