WO2021022800A1

WO2021022800A1 - Surface preparation method capable of preparing various nanowire structures

Info

Publication number: WO2021022800A1
Application number: PCT/CN2020/073161
Authority: WO
Inventors: 马学虎; 杨思艳; 温荣福; 杜宾港; 于星瞳; 陶沿宪; 郝婷婷; 兰忠; 白涛
Original assignee: 大连理工大学
Priority date: 2019-08-02
Filing date: 2020-01-20
Publication date: 2021-02-11
Also published as: CN111218702A; CN111218702B; CN110387565A

Abstract

A surface preparation method capable of preparing various nanowire structures, belonging to the technical field of surface treatment. In said method, a template-assisted electroplating method is used to form, by changing the hole spacing and hole diameter and duration of electroplating of the template, various structural morphologies, such as an upright structural morphology, an agglomerated structural morphology and a round-pit structural morphology, and the structural heights and angles of the upright structural morphology and the agglomerated structural morphology can be changed. The height of the nanowire is 4-50 μm, the center distance of the nanowire is 60-500 nm, and the diameter of the nanowire is 5-400 nm. The upright structural morphology, the agglomerated structural morphology and the round-pit structural morphology which are prepared by means of said preparation method have a controllable surface morphology and a diversified structural form and can span scales, the upright structural morphology and the agglomerated structural morphology can be applied to condensation, and the round-pit structural morphology can be applied to the field of phase change heat transfer, such as boiling.

Description

Surface preparation method capable of preparing multiple nanowire structures

Technical field

The invention relates to a copper nanowire surface, in particular to a method for preparing a copper nanowire surface that can form upright, agglomerated, and round pit shapes. Its main feature is that it uses a template to assist the preparation by electroplating The surface of copper nanowires with different pitches and wire diameters can be used to effectively enhance the field of phase change heat transfer such as condensation and boiling due to its different structure and morphology, and belongs to a functional structure.

Background technique

How to improve the surface structure to maximize the effects of condensation heat transfer and boiling heat transfer has always been a research hotspot in the field of heat management and water collection. In the field of condensation heat transfer, the extremely small condensation droplets on the surface of nanostructures can cause coalescing and induce droplets to bounce and get rid of the restriction of gravity. However, most nanostructures are limited to only a small amount of heat transfer efficiency. Surface subcooling (△T<5K). In a larger surface subcooling range, uncontrollable heterogeneous nucleation will cause the appearance of condensation flooding mode, which greatly limits the improvement of the heat transfer performance of the nanostructured surface . Compared with the traditional wettability control surface, the upright and agglomerated nanowire surface with high aspect ratio, due to its good spatial confinement effect, can fully reduce the entry of water vapor molecules into the superhydrophobic nanometer on the condensation surface The possibility inside the wire structure limits the appearance of the submerged mode within a large subcooling range, which can greatly increase the heat transfer flux. The literature "Hydrophobic copper nanowires for enhancingcondensation heat transfer.(Nano Energy,2017,33:177–183)" and "Three-Dimensional Superhydrophobic Nanowire Networks for Enhancing Condensation Heat Transfer (Joule,2018,2(2)269-279) "Both use copper nanowires to achieve a substantial increase in condensation heat transfer performance under large subcooling. In the field of boiling heat transfer, the surface with micro-nanoporous structure also shows excellent advantages in improving boiling heat transfer performance. The document "Effects of nanowire height on pool boiling performance of water on silicon chips (International Journal of Thermal Sciences) , 2011, 50: 2084-2090)” reported that the hole-like structure formed by silicon nanowires has significantly improved boiling heat transfer effect compared to vertical silicon nanowires and vertical copper nanowires. The document "Enhancement of Saturation Boiling of PF-5060 on Microporous Copper Dendrite Surfaces (Journal of Heat Transfer, 2010, 132:071501-1)" utilizes the pit structure formed by copper nanowires. The larger the hole, the greater the heat transfer effect. Great. In the preparation of copper nanowires, gas phase method, liquid phase method, solvothermal method, and template method are more commonly used, and there are fewer studies on the preparation of copper nanowires by electrodeposition. In the literature "Large-scale synthesis of high-quality ultralong copper nanowires. (Langmuir, 2005, 21(9): 3746-3748.)", high-quality copper nanowires were synthesized by the liquid phase method. The literature "Sythesis of ultralong copper nanowires for high-performance transparent electrode. (Journal of the American Chemical Society, 2012, 134(35): 14283-14286)" developed a synthesis of 78nm in diameter and length from an organic amine system. The method of copper nanowires from ten to several hundred microns. Patent CN201810220699.0 discloses a copper nanowire prepared by the solvothermal method of organic amine hexadecane and reducing sugar in copper chloride powder using copper nitrate. Patent CN201610837753.7 discloses a method for preparing copper nanowires by first baking and then chemical reduction. Patent CN201810454313.2 discloses a method for preparing copper nanowires by a sol-gel method. In summary, at present, researchers in related fields have used a variety of methods to prepare copper nanowires, but there are rare reports on the use of template method combined with electrochemical deposition to prepare copper nanowires. Patent CN105483795 discloses a method for preparing composite copper nanowires using underpotential deposition technology. Copper nano. A metal monoatomic layer is deposited on the surface of copper by under-potential to prepare composite metal nanowires. First of all, this patent uses a template-assisted electrochemical deposition method like this patent, but this patent uses a double-pass AAO (porous anodic aluminum oxide) template, and the prepared nanowires grow directly on the cathode surface; The patent uses a single-pass AAO template, and the prepared nanowires are dispersed in the solution after the template is dissolved, with no place to attach. Secondly, this patent only needs self-assembled hydrophobic substance to achieve the effect of preventing the oxidation of copper nanowires, which is simpler and easier than the patent of depositing a metal monoatomic layer to resist oxidation. Finally, this patent uses only one method to prepare micro-nano composite structures with multiple morphologies formed by multiple nanowires. Upright and agglomerated types can be used to effectively improve condensation heat transfer, while round pits can be used to effectively improve Boiling heat transfer, in general, shows great potential in the field of phase change heat transfer; the patent is a single dispersed nanowire used in a transparent electrode, and the uses of the two are quite different.

Summary of the invention

In order to solve the problems in the prior art, the present invention provides a surface preparation method of copper nanowires containing a variety of micro-nano composite structures. A single method can be used to prepare micro-shaped microstructures formed by multiple nanowires. Nanocomposite structure, upright type and agglomeration type can be used to effectively improve condensation heat transfer, while round pit type can be used to effectively improve boiling heat transfer, showing great potential in the field of phase change heat transfer.

The technical scheme adopted by the present invention is: a surface preparation method capable of preparing a variety of nanowire structures. By controlling the template hole spacing, aperture, and electroplating time, it can form upright, agglomerated, and round pit structures with a height of about 4 -50μm, the distance between the centers of the nanowires is between 60-500nm, and the diameter of the nanowires is between 5-400nm.

The method includes the following steps:

Step 1 Take the red copper block, polish and degrease it ultrasonically. Using the two-electrode system, put the organic glass block, the cathode red copper block connected to the working electrode, the porous anodic aluminum oxide template (AAO), and the electroplating solution in the fixture from bottom to top. Wet the filter paper, the anode copper block and the plexiglass block connected to the counter electrode, and the entire system is fully clamped, and the electrochemical workstation is set to voltage and time for electroplating;

Step 2 On the basis of the two-electrode system in step 1, add a reference electrode to an electroplating device to form a three-electrode system, so that the distance between the anode copper block and the cathode copper block is 10-30mm, and the distance between the reference electrode and the two electrodes The distance is equal, and the electrochemical workstation is set to voltage and time for electroplating;

Step 3 Dissolve the anodic aluminum oxide template with NaOH, rinse and dry the upright and agglomerated surfaces and put them in octadecyl mercaptan in a water bath at 70°C for 1 hour. This step is ignored for round pit-shaped surfaces. The electroplating solution is prepared according to the mass ratio of copper pyrophosphate: potassium pyrophosphate: triammonium citrate: deionized water = 5:30:3:100, and the pH value should be between 7-9.

In the step 1, the voltage is set to -0.5 to -1.5V, and the time is set to 600-1200s.

In the step 2, the voltage is set to -0.5 to -1.5V, and the time is set to 1800-18000s.

The beneficial effects of the present invention are: a method for preparing copper nanowire surfaces with various morphologies of upright, agglomerated and round pits. The upright and agglomerated surfaces are superhydrophobic and can be used for effective strengthening Condensation heat transfer; the pit-shaped surface is super-hydrophilic and can be used to effectively enhance boiling heat transfer. The copper nanowire surface prepared by this patent can show great potential in the field of phase change heat transfer. Compared with other patents, this patent can use one preparation method to prepare micro-nano composite surfaces with different structures and morphologies, and can use different structures and morphologies to achieve different purposes. This method uses a template-assisted electroplating method. By changing the template hole spacing, aperture and electroplating time, it can form upright, agglomerated, round pit and other structural morphologies, and can change the height and structure of the upright and agglomerated types. Included angle. The height of the nanowire is 4-50μm, the center distance of the nanowire is 60-500nm, and the diameter of the nanowire is 5-400nm. The surface morphology obtained by the preparation method is controllable, the structure is diversified, and can be cross-scaled. The upright type and the agglomerated type can be used for condensation, and the round pit type can be used for phase change heat transfer fields such as boiling. This application uses only one method to prepare micro-nano composite structures with multiple morphologies formed by multiple nanowires. The upright type and the agglomeration type can be used to effectively improve the condensation heat transfer, and the round pit type can be used to effectively improve the boiling transfer. Heat, in general, shows great potential in the field of phase change heat transfer.

Description of the drawings

Fig. 1 is a structural diagram of a clamp device used in an embodiment of the present invention.

Figure 2 is a schematic flow diagram of the present invention.

Fig. 3 is an SEM image of the surface of the copper nanowire structure of upright, agglomerated and round pit in Example 1 of the present invention. Among them: the magnification is 10000 times, the scale is 20μm. Upright type: (a) The average center distance of nanowires prepared with 450-360 template is about 450nm, and the wire diameter is 360nm; (b) The average center distance of nanowires prepared with 450-200 template is about 432nm, and the wire diameter It is 280nm, the average spacing of the microgrooves formed after the nanowires agglomerates is 2.8μm; agglomeration type: (c) The average center distance of the nanowires prepared by the 450-200 template is 335nm, the wire diameter is 200nm, and the nanowires agglomerate The average spacing of the microgrooves formed afterwards is 8.5μm; (d) The average center distance of the nanowires prepared using the 450-110 template is 278nm, the wire diameter is 110nm, and the average microgrooves formed after the nanowires agglomerate The pitch is 21μm; the round pit type: (e) the diameter of the nanowire prepared by the 125-30 template is 30nm, the average diameter of the pit formed after the nanowire agglomeration is 12μm, the average center distance of the pit is 15μm, The average thickness of the pits is 3μm; (f) the diameter of the nanowires prepared by the 65-10 template is 10nm, the average diameter of the pits formed after the nanowires agglomerates is 10μm, the average center distance of the pits is 17μm, and the pits The average thickness is 2μm.

Fig. 4 is an SEM image of the surface of the upright and agglomerated copper nanowires with different heights in Example 2 of the present invention. Among them: the pictures are all enlarged 10000 times, the scale bar is 20μm. (a) The height of the nanowires prepared by using the 450-200 template after electroplating for 3 hours is about 10.9 μm; (b) The height of the nanowires prepared by using the 450-200 template after electroplating for 4 hours is about 42 μm; (c) The height of the nanowires prepared with the 450-200 template is over 50μm after 5h of electroplating; (d) the height of the nanowires prepared with the 450-360 template is about 4.5μm after 1h of electroplating; (e) using 450- The height of the nanometer prepared by 360 template is about 9.4 μm after electroplating for 2 hours; (f) the height of the nanometer prepared by using the 450-360 template after electroplating for 3 hours is about 11.2 μm.

detailed description

The following examples are used to illustrate the present invention.

Example 1

Surface preparation of upright, agglomerated and round pit copper nanowire structures

A. Take the red copper block and polish it with sandpaper, and put it in acetone, ethanol, and deionized water for 10 minutes, and then take it out and blow dry with nitrogen.

B. Put the plexiglass block, the red copper block connected to the working electrode, the porous anodic aluminum oxide template, the filter paper dripped with electroplating solution, the red copper block connected to the counter electrode, the plexiglass block in sequence from bottom to top, and fully clamp Tight, template models are 450-360, 450-280, 450-200, 450-110, 125-30, 65-10. The electrochemical workstation voltage is set to -0.8V, and the time is set to 900s.

The clamp used in this embodiment is shown in Figure 1. When in use, on the bottom plate 4 of the clamp shown, put the organic glass block, the red copper block connected to the working electrode, the porous anodized aluminum template, and the electroplating from bottom to top. Liquid filter paper, copper block and organic glass block connected to the electrode, and rotate the screw 1 to move the middle plate 3 downwards until the entire system is fully clamped.

C. Working options of the three-electrode system: the distance between the copper block covered with the template and the other copper block is 20mm, and the distance between the reference electrode and the two electrodes is 10mm. The electrochemical workstation voltage is set to -0.8V, and the time is set to 10800s.

D. Rinse the copper block with deionized water and then dissolve the porous anodic aluminum oxide template with 2mol/L NaOH, thoroughly rinse the copper block with deionized water and then dry it with nitrogen, then put it in a 0.0025mol/L Place the stearyl mercaptan in a beaker and seal it tightly. Put the beaker in a 70°C water bath, take out the beaker after 1 h, and take out the copper block in the beaker and blow dry with nitrogen.

E. Use 450-360 and 450-280 models of porous anodic aluminum oxide templates, and the copper nanowire surface is upright, as shown in Figure 3 (a) and (b); models 450-200 and 450-110 are used The porous anodic alumina template of the copper nanowires is agglomerated, as shown in Figure 3 (c) and (d); the 125-30 and 65-10 porous anodic alumina templates are used, and the copper nanowires The surface is round pits, as shown in Figure 3 (e) and (f). Therefore, by controlling the wire spacing and wire diameter, it can present a variety of structural morphologies such as upright, agglomerated, and round pits. Among them, the upright and agglomerated structure surfaces are conducive to condensation heat transfer, and the round pits are conducive to boiling heat transfer. .

Example 2

Surface preparation of upright and agglomerated copper nanowires with different heights

B. In the two-electrode system provided by the fixture, put the plexiglass block, the red copper block connected to the working electrode, the porous anodized aluminum template, the filter paper dripped with electroplating solution, the red copper block connected to the counter electrode, and the organic glass from bottom to top. Block, and fully clamped, the template model is 450-360, 450-200. The electrochemical workstation voltage is set to -0.8V, and the time is set to 900s.

The clamp used in this embodiment is shown in Figure 1. When in use, on the bottom plate 4 of the clamp, put the plexiglass block, the red copper block connected to the working electrode, the porous anodized aluminum template, and the electroplating solution from bottom to top. Filter paper, copper block and organic glass block connected to the electrode, and rotate the screw 1 to move the middle plate 3 downwards until the entire system is fully clamped.

C. In the three-electrode system provided by the electroplating bath, the distance between the cathode copper block and the anode copper block is 20mm, and the distance between the reference electrode and the two electrodes is 10mm. The voltage is set to -0.8V. When the 450-360 model is selected, the time is set to 3600s, 7200s, and 10800s. When the 450-200 template is selected, the time is set to 10800s, 14400s, and 18000s respectively.

D. Rinse the copper block with deionized water and then dissolve the porous anodic aluminum oxide template with 2mol/L NaOH, thoroughly rinse the copper block with deionized water and then dry it with nitrogen, then put it in a 0.0025mol/L Put the octadecyl mercaptan in the beaker into a 70°C water bath, take out the beaker after 1 h, and take out the copper block in the beaker and blow dry with nitrogen.

F. Use 450-200 model porous anodic aluminum oxide template. The second electroplating time is 3h, 4h and 5h respectively. The height of 3h is about 10.9μm, the height of 4h is about 42μm, and the height of electroplating 5h is greater than 50μm; -360 type porous anodic aluminum oxide template, the second electroplating time is 1h, 2h and 3h respectively. The height of 1h is about 4.5μm, the height of 2h is about 9.4μm, and the height of 3h is about 11.2μm. For the surface of agglomerated (450-200) nanowires, the higher the height, the more conducive it is to restrict water molecules from entering the structure under low-pressure experimental conditions to form the phenomenon of submergence, which is conducive to achieving a larger subcooling range Condensation in drops to enhance heat transfer; for nanowires with an upright (450-360) morphology, the higher the height, the more obvious the agglomeration phenomenon, and the larger the angle of the structure formed after agglomeration. Under the appropriate angle, It is beneficial to promote the merging of droplets to induce bounce under normal pressure experimental conditions, thereby helping to enhance heat transfer.

Claims

A surface preparation method capable of preparing a variety of nanowire structures, which is characterized in that it can form upright, agglomerated, and round pit-shaped structures by controlling the template hole spacing, aperture, and electroplating time, with a height of about 4-50μm, and nanowires The theoretical center distance is between 60-500nm, and the diameter of the nanowire is between 5-400nm;

The method includes the following steps:

Step 1 Take the red copper block, polish and degrease it ultrasonically. Using the two-electrode system, put the plexiglass block, the cathode red copper block connected to the working electrode, the porous anodic aluminum oxide template, and the one wetted by the electroplating solution in the fixture from bottom to top. Filter paper, anode copper block and plexiglass block connected to the counter electrode, and fully clamped, electrochemical workstation set voltage and time for electroplating;

Step 2 On the basis of the two-electrode system in step 1, add a reference electrode to an electroplating device to form a three-electrode system so that the distance between the anode copper block and the cathode copper block is 10-30mm, and the distance between the reference electrode and the two electrodes The distance is equal, and the electrochemical workstation is set to voltage and time for electroplating;

Step 3 Use NaOH to dissolve the anodic aluminum oxide template, rinse and dry the surfaces of the upright and agglomerated types, and put them in stearyl mercaptan, and heat in a water bath at 70°C for 1 hour.
The surface preparation method capable of preparing multiple nanowire structures according to claim 1, wherein the electroplating solution is based on a mass ratio of copper pyrophosphate: potassium pyrophosphate: triammonium citrate: deionized water = 5: The ratio is 30:3:100, and the pH value is between 7-9.
The surface preparation method capable of preparing multiple nanowire structures according to claim 1, wherein in step 1, the voltage is set to -0.5 to -1.5V, and the time is set to 600-1200s.
The surface preparation method capable of preparing multiple nanowire structures according to claim 1, wherein in step 2, the voltage is set to -0.5 to -1.5V, and the time is set to 1800-18000s.