Preparation method of surface-roughened iron oxide nanotube

Abstract

The present application relates to a kind of preparation methods of surface roughness iron oxide nanotube, belong to battery material technical field.The method of the present application is on the anodic aluminum oxide template of double-pass nanometer channel, using electrochemical hydrogen assisted deposition method to prepare Fe nanotube array.Fe nanotube array is slowly oxidized in secondary oxidation process, and forms surface roughness iron oxide nanotube.This method prepares the surface roughness iron oxide nanotube, and surface effect will be more obvious, which is beneficial to its application in lithium ion battery, chemical sensor and water splitting hydrogen electrode and other fields.

Description

Technical Field

[0001] This invention relates to a method for preparing iron oxide nanotubes with rough surfaces, belonging to the field of battery materials technology. Background Technology

[0002] In lithium-ion batteries, iron oxide is one of the most promising anode materials to replace graphite. Iron oxide possesses excellent reversibility and a high theoretical capacity, but it suffers from poor capacity retention and low efficiency. To overcome these drawbacks, considerable effort has been devoted to researching various iron oxide-based electrode materials. One feasible solution is to fabricate iron oxide with specific nanostructures, such as nanoparticles, nanorods, nanotubes, and microspheres. The one-dimensional nanostructure of iron oxide nanotubes exhibits significant advantages, including increased contact surface area between the electrolyte and active material and shortened electron migration paths. Therefore, the fabrication of iron oxide nanotubes, especially those with high specific surface area, presents an attractive challenge.

[0003] The main method for preparing iron oxide nanotubes is currently anodic oxidation. CN102311153A uses metallic iron as the substrate, which serves as the working electrode, and a platinum sheet as the counter electrode. Electrochemical anodic oxidation is performed in an electrolyte to obtain an ordered array of iron oxide nanotubes on the iron substrate surface. The principle of this method is to first prepare FeOOH nanotubes via anodic oxidation, followed by heat treatment to produce iron oxide nanotubes. The literature doi:10.1021 / jp904560n also uses anodic oxidation to prepare iron oxide nanotubes, resulting in nanotubes with uniform wall thickness and smooth surfaces. Summary of the Invention

[0004] This invention provides a method for preparing iron oxide nanotubes with rough surfaces. This method can stably prepare iron oxide nanotubes with rough surfaces and large specific surface areas, and the operation process is simple.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing iron oxide nanotubes with roughened surfaces, the method comprising the following steps: Preparation of anodic alumina template with dual-channel nanopores Pretreated high-purity aluminum sheets are placed in an oxalic acid solution for a first anodization to obtain a primary aluminum oxide sheet with an oxide film formed on the surface. Then, the oxide film is removed by placing the sheet in a mixed aqueous solution of phosphoric acid and chromic acid. The aluminum sheet is then placed in an oxalic acid solution for a second anodization, and then placed in an aqueous solution of copper chloride to remove the substrate. Finally, the sheet is placed in an aqueous solution of phosphoric acid to expand the pores, resulting in an anodized aluminum template with dual-channel nanopores.

[0006] (b) Potentially constant deposition of Fe nanotubes (b-1) Sputtering conductive layer: A copper film is sputtered by fixing an anodic aluminum oxide template in a magnetron sputtering fixture; (b-2) Constant potential electrodeposition: In the three-electrode system, the anodic aluminum oxide template treated in (b-1) is used as the working electrode, the platinum sheet is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. The saturated calomel electrode is immersed in a saturated KCl solution, and the working electrode and the counter electrode are immersed in an electrolyte containing ferrous iron. The saturated KCl solution and the electrolyte are connected by a salt bridge to perform electrodeposition. (c) Oxygenated Fe nanotubes (c-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (b-2) is cleaned with deionized water and ethanol; (c-2) First oxidation: The (c-1) alumina template is placed in a high-temperature and high-humidity oven for baking; (c-3) Second oxidation: The (c-2) alumina template is placed in a tube furnace and baked in high temperature pure oxygen; (d) Releasing iron oxide nanotubes: Immerse the anodic aluminum oxide template from step (c-2) in the post-treatment solution to remove the aluminum oxide template and copper film, thereby obtaining the roughened iron oxide nanotubes.

[0007] Preferably, in step (b-2), the electrolyte contains soluble deposited salt, boric acid, and soluble electrolyte salt. Specifically, the electrolyte composition includes 10~30 g / L FeSO4•6H2O, 6~8 g / L NaCl, 3~5 g / L H3BO3, and 1-2 g / L ascorbic acid.

[0008] Preferably, step (b-2) further includes immersing the working electrode and the counter electrode in the electrolyte, stirring at a stirring rate of 200 r / min for 30 min and then stopping the stirring, connecting the saturated KCl solution and the electrolyte with a salt bridge, and performing electrodeposition.

[0009] Preferably, the deposition conditions in step (b-2) are pH 3-4, deposition voltage 2-3V, deposition time 150-300s, and deposition temperature 20-30℃.

[0010] Preferably, the baking temperature in step (c-2) is 65-95℃, the humidity during baking is 35-85%, and the baking time is 12-18h.

[0011] Preferably, in step (c-3), the temperature of the tubular furnace is 150-200℃, the holding time is 0.5-1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0012] Preferably, in step (d), the post-treatment solution is a 0.5~1.0 mol / L sodium hydroxide solution, and the soaking time is 50-70 min.

[0013] Step (a) specifically includes the following detailed process: (a-1) Primary oxidation: High-purity aluminum sheets that have undergone annealing and ultrasonic washing pretreatment are placed in an oxalic acid aqueous solution for primary anodizing to obtain primary aluminum oxide sheets with an oxide film formed on the surface; (a-2) Removal of primary oxide film: Take a primary alumina sheet, immerse it in a mixed aqueous solution of phosphoric acid and chromic acid, and then rinse it with water to obtain an aluminum sheet with the surface oxide film removed; (a-3) Secondary oxidation: The aluminum sheet with the surface oxide film removed is placed in an oxalic acid aqueous solution for secondary anodizing. During the oxidation process, the oxidation voltage gradually decreases. (a-4) Removing the substrate: Take out the aluminum sheet after secondary oxidation, wash it with water, then soak it in copper chloride solution, and then wash it clean with water; (a-5) Pore enlargement: The aluminum sheet without substrate is placed in a phosphoric acid aqueous solution to enlarge the pores, thereby obtaining anodized aluminum template with double nanopores.

[0014] The alumina template produced has open channels both top and bottom. A copper film is then sputtered onto one side as a conductive film, while the other side serves as a liquid inflow channel. The purpose of the two oxidation processes is to make the channels of the oxidized AAO template more ordered. After the first oxidation, the oxide layer is removed, resulting in oxide pits on the aluminum sheet. These pits serve as sites for the second oxidation, thus making the channels more ordered.

[0015] This invention describes a method for preparing Fe nanotube arrays using secondary-oxidized AAO as a template via electrochemical hydrogen-assisted deposition. The Fe nanotube array undergoes slow oxidation during the secondary oxidation process, forming rough-surfaced iron oxide nanotubes. The rough surface of the iron oxide nanotubes prepared by this method results in more pronounced surface effects, which is beneficial for their application in lithium-ion batteries, chemical sensors, and photocatalytic water splitting hydrogen production electrodes. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the preparation process of the roughened iron oxide nanotubes of the present invention.

[0017] Figure 2 This is a scanning electron microscope image of the surface-roughened iron oxide nanotubes prepared in Example 1.

[0018] Figure 3 This is the XRD pattern of the nanotubes prepared in Example 1.

[0019] Figure 4This is a scanning electron microscope image of the surface-roughened iron oxide nanotubes prepared in Example 2.

[0020] Figure 5 This is a scanning electron microscope image of the surface-roughened iron oxide nanotubes prepared in Example 3.

[0021] Figure 6 This is a scanning electron microscope image of the iron nanowires prepared in Comparative Example 1.

[0022] Figure 7 This is the XRD pattern of the nanotubes prepared in Comparative Example 2.

[0023] Figure 8 This is the XRD pattern of the nanotubes prepared in Comparative Example 3.

[0024] Figure 9 The image shows a comparison of SEM images of nanotubes prepared in Comparative Example 4 and Example 1.

[0025] Figure 10 This is the XRD pattern of the nanotubes prepared in Comparative Example 5.

[0026] Figure 11 This is the XRD pattern of the nanotubes prepared in Comparative Example 6. Detailed Implementation

[0027] Example

[0028] (1) Template preparation (1-1) Select high-quality, high-purity (99.999wt%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0029] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8h, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0030] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0031] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed was placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage was 80V, the oxidation time was 30 min, it was taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0032] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0033] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97 ml of distilled water and 3 g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30 g of KCl to dissolve it completely. Finally, pour the solution into a U-shaped thin glass tube while it is still hot. After the agar solidifies, the salt bridge is obtained.

[0034] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4 × 10⁻⁶. -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0035] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0036] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0037] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned 3 times with deionized water and 1 time with ethanol.

[0038] (3-2) First oxidation: The cleaned Fe nanotube-containing alumina template was placed in a high temperature and high humidity chamber at a temperature of 95℃ and a humidity of 35% for 18 hours.

[0039] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0040] (4) Release nanotubes: The anodic aluminum oxide template of (3-3) is soaked in the post-treatment solution (1mol / L NaOH) for 1h to fully remove the oxide film, thereby obtaining the rough iron oxide nanotubes. Example

[0041] (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0042] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8h, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0043] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 hours to remove the primary oxide film, and then rinse with deionized water.

[0044] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed was placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage was 80V, the oxidation time was 30 min, it was taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0045] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0046] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97ml of distilled water and 3g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0047] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0048] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 300s, and deposition temperature 20℃.

[0049] The electrolyte composition is: 30 g / L FeSO4•6H2O, 8 g / L NaCl, 5 g / L H3BO3, and 2 g / L ascorbic acid.

[0050] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0051] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity machine at a temperature of 95℃ and a humidity of 35% for 18 hours.

[0052] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0053] (4) Release nanotubes: The anodic aluminum oxide template of (3-3) is soaked in the post-treatment solution (1mol / L NaOH) for 1h to fully remove the oxide film, thereby obtaining the rough iron oxide nanotubes. Example

[0054] (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0055] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8h, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0056] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0057] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed was placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage was 80V, the oxidation time was 30 min, it was taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0058] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0059] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97 ml of distilled water and 3 g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30 g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0060] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0061] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150 s, and deposition temperature 20℃.

[0062] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0063] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0064] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity machine at a temperature of 65℃ and a humidity of 85% for 12 hours.

[0065] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0066] (4) Release nanotubes: The electrodeposited anodic aluminum oxide template is immersed in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining the rough iron oxide nanotubes.

[0067] Comparative Example 1 (1) Template preparation (1-1) Select high-quality, high-purity (99.999wt%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0068] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8 hours, with an electrolyte concentration of 0.3mol / L oxalic acid.

[0069] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 hours to remove the primary oxide film, and then rinse with deionized water.

[0070] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed is placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage is 80 V, the oxidation time is 30 min, it is taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0071] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0072] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97 ml of distilled water and 3 g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30 g of KCl to dissolve it completely. Finally, pour the solution into a U-shaped thin glass tube while it is still hot. After the agar solidifies, the salt bridge is obtained.

[0073] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0074] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0075] The electrolyte consists of 10 g / L FeSO4•6H2O, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0076] (3) Release of nanowires: The electrodeposited anodic aluminum oxide template is soaked in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining Fe nanowires.

[0077] Comparative Example 2 (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0078] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8 hours, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0079] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0080] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed is placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage is 80 V, the oxidation time is 30 min, it is taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0081] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0082] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97 ml of distilled water and 3 g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30 g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0083] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4 × 10⁻⁶. -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0084] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0085] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0086] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0087] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity machine at a temperature of 100℃ and a humidity of 35% for 18 hours.

[0088] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0089] (4) Release nanotubes: The electrodeposited anodic aluminum oxide template is immersed in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining the rough iron oxide nanotubes.

[0090] Comparative Example 3 (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0091] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8 hours, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0092] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0093] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed is placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage is 80 V, the oxidation time is 30 min, it is taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0094] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0095] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97ml of distilled water and 3g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0096] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0097] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0098] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0099] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0100] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity machine at a temperature of 95℃ and a humidity of 25% for 18 hours.

[0101] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0102] (4) Release nanotubes: The electrodeposited anodic aluminum oxide template is immersed in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining the rough iron oxide nanotubes.

[0103] Comparative Example 3 (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0104] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8 hours, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0105] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0106] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed is placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage is 80 V, the oxidation time is 30 min, it is taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0107] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0108] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97ml of distilled water and 3g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0109] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0110] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0111] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0112] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0113] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity machine at a temperature of 95℃ and a humidity of 25% for 18 hours.

[0114] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0115] (4) Release nanotubes: The electrodeposited anodic aluminum oxide template is immersed in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining the rough iron oxide nanotubes.

[0116] Comparative Example 4 (1-1) Use 1200 ml of 0.5 mm iron sheet (99.9%) to... # Sand it with sandpaper, and then ultrasonically clean it for 20 minutes each in distilled water and acetone.

[0117] (1-2) In the electrolytic solution, the iron sheet from (1-1) is used as the working electrode, the platinum sheet is used as the counter electrode, the voltage is 45V, the temperature is 60℃, and the electrochemical oxidation time is 15 minutes. (2-1) The iron electrode of (1-2) was ultrasonically cleaned in isopropanol and then heat-treated in a muffle furnace at a temperature of 500℃, a heating rate of 1℃ / min, an oxygen atmosphere, and a heat treatment time of 1 hour.

[0118] (1-2) The electrolyte is an ethylene glycol solution of 0.3wt% NaF, 0.5wt% HF, and 3% vol H2O.

[0119] Comparative Example 5 (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0120] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8 hours, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0121] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0122] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed is placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage is 80 V, the oxidation time is 30 min, it is taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0123] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0124] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97ml of distilled water and 3g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0125] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0126] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0127] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0128] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0129] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity machine at a temperature of 95℃ and a humidity of 95% for 18 hours.

[0130] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0131] (4) Release nanotubes: The electrodeposited anodic aluminum oxide template is immersed in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining the rough iron oxide nanotubes.

[0132] Comparative Example 6 (1) Template preparation (1-1) Select high-quality, high-purity (99.999%) aluminum sheets and anneal them at 500℃ for 4 hours. Then, sonicate them in acetone for 10 minutes, soak them in 5% (wt) sodium hydroxide for 5 minutes, and finally sonicate them in acetone for 3 minutes to complete the pretreatment of the aluminum sheets.

[0133] (1-2) First oxidation: The pretreated aluminum sheet was etched at 80V and 0℃ for 8 hours, with an electrolyte concentration of 0.3 mol / L oxalic acid.

[0134] (1-3) Removal of primary oxide film: After removal, immerse in a mixed solution of 50℃, 6% (wt) phosphoric acid and 1.5% (wt) chromic acid for 12 h to remove the primary oxide film, and then rinse with deionized water.

[0135] (1-4) Second oxidation: The aluminum sheet with the first oxide film removed is placed in a 0.7 mol / L oxalic acid aqueous solution, the oxidation voltage is 80 V, the oxidation time is 30 min, it is taken out and washed with deionized water, and then soaked in a 3 mol / L CuCl2 aqueous solution for 20 min, and then washed clean with deionized water to obtain an alumina template containing double nanopores.

[0136] (1-5) Hole expansion: The aluminum sheet was placed in 8% (wt) H3PO4 at 40℃ for 30 min to expand the hole and obtain the anodic aluminum template.

[0137] (2) Potentially constant deposition of Fe nanotubes (2-1) Preparation of salt bridge: Add 97ml of distilled water and 3g of agar to a beaker and heat in a water bath until completely dissolved. Then add 30g of KCl to dissolve it completely. Finally, pour it into a U-shaped thin glass tube while hot and wait for the agar to solidify to obtain the salt bridge.

[0138] (2-2) Sputtering the conductive layer: The anodic aluminum oxide template obtained in step (a) is fixed in the magnetron sputtering fixture, and the argon flow rate is 20 sccm and the gas pressure is 4×10 -4 A copper film was sputtered under a self-bias voltage of 175 Pa. After copper plating, the electrolyte and the anodic aluminum oxide template were placed under a nitrogen atmosphere for 2 hours.

[0139] (2-3) Potentially constant deposition: In the three-electrode system, the anodic aluminum oxide template obtained in step (2-2) was used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the auxiliary electrode. The auxiliary electrode was immersed in a saturated KCl solution, and the saturated KCl solution and the electrolyte were connected by a salt bridge. After adding the electrodeposition solution, the stirring rate was 200 r / min for 30 min. After stirring was stopped, electrodeposition was carried out under the following conditions: pH=3, deposition voltage 3V, deposition time 150s, and deposition temperature 20℃.

[0140] The electrolyte composition is: 10 g / L FeSO4•6H2O, 6 g / L NaCl, 3 g / L H3BO3, and 1 g / L ascorbic acid.

[0141] (3) Oxygenated Fe nanotubes: (3-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (2-3) was cleaned three times with deionized water and once with ethanol.

[0142] (3-2) First oxidation: The cleaned and dried Fe nanotube-containing alumina template was placed in a high temperature and high humidity chamber at a temperature of 60℃ and a humidity of 35% for 18 hours.

[0143] (3-3) Second oxidation: The alumina template of (3-2) is placed in a tube furnace. The temperature of the tube furnace is 150℃, the holding time is 1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen.

[0144] (4) Release nanotubes: The electrodeposited anodic aluminum oxide template is immersed in a post-treatment solution (1 mol / L NaOH) for 1 h to fully remove the oxide film, thus obtaining the rough iron oxide nanotubes.

[0145] Summary of the examples and comparative examples: 1. Compared with Example 1, Comparative Example 1 did not add NaCl, such as Figure 6 The electrochemical deposition of Fe nanowires instead of nanotubes shows that nanotubes cannot be deposited without the addition of soluble electrolyte salts.

[0146] 2. Compared to Example 1, Comparative Example 2 increased the oxidation temperature to 100°C. Figure 7 XRD analysis showed a distinct iron tetroxide peak, indicating that the oxidation temperature was not suitable for being too high.

[0147] 3. Compared to Example 1, Comparative Example 3 reduced the humidity to 25%. Figure 8 XRD analysis showed that it did not undergo significant oxidation and was mostly elemental Fe, indicating that the humidity should not be too low.

[0148] 4. Compared with Example 1, Comparative Example 4 used an electrochemical oxidation method to prepare iron oxide nanotubes. Figure 9 SEM images show that the nanotube surface is smooth, similar to Example 1. Figure 9 The surfaces of b nanotubes show obvious differences.

[0149] 5. Compared to Example 1, Comparative Example 5 increased the humidity to 95%. Figure 10XRD analysis showed the presence of some iron(III) oxide, indicating that the humidity level should not be too high.

[0150] 6. Compared to Example 1, Comparative Example 6 reduced the oxidation temperature to 60°C. Figure 11 XRD analysis showed the presence of iron tetroxide peaks, indicating that the temperature was not suitable for being too low.

Claims

1. A method for preparing iron oxide nanotubes with a rough surface, characterized in that, The preparation method includes the following steps: (a) Preparation of anodized aluminum template with dual-channel nanopores Pretreated high-purity aluminum sheets are placed in oxalic acid solution for a first anodization to obtain a primary aluminum oxide sheet with an oxide film formed on the surface. Then, the oxide film is removed by placing the sheet in a mixed aqueous solution of phosphoric acid and chromic acid. The aluminum sheet is then placed in oxalic acid solution for a second anodization. The substrate is then removed by placing the sheet in an aqueous solution of copper chloride. Finally, the sheet is placed in an aqueous solution of phosphoric acid to expand the pores, resulting in an anodized aluminum template with dual-channel nanopores. (b) Potentially constant deposition of Fe nanotubes (b-1) Sputtering conductive layer: A copper film is sputtered by fixing an anodic aluminum oxide template in a magnetron sputtering fixture; (b-2) Constant potential electrodeposition: In the three-electrode system, the anodic aluminum oxide template treated in (b-1) is used as the working electrode, the platinum sheet is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. The saturated calomel electrode is immersed in a saturated KCl solution, and the working electrode and the counter electrode are immersed in an electrolyte containing ferrous iron. The saturated KCl solution and the electrolyte are connected by a salt bridge to perform electrodeposition. In step (b-2), the electrolyte composition includes 10-30 g / L FeSO4•6H2O, 6-8 g / L NaCl, 3-5 g / L H3BO3, and 1-2 g / L ascorbic acid. The deposition conditions are pH 3-4, deposition voltage 2-3V, deposition time 150-300s, and deposition temperature 20-30℃. (c) Oxygenated Fe nanotubes (c-1) Cleaning Fe nanotubes: The alumina template with Fe nanotubes deposited in step (b-2) is cleaned with deionized water and ethanol; (c-2) First oxidation: The (c-1) alumina template is placed in a high temperature and high humidity oven for baking; the baking temperature in step (c-2) is 65-95℃, the humidity is 35-85%, and the baking time is 12-18h; (c-3) Second oxidation: The (c-2) alumina template is placed in a tube furnace for high-temperature pure oxygen baking; in step (c-3), the temperature of the tube furnace is 150-200℃, the holding time is 0.5-1h, the heating rate is 0.2℃ / min, and the atmosphere is oxygen. (d) Releasing iron oxide nanotubes: Immerse the anodic aluminum oxide template from step (c-3) in the post-treatment solution to remove the aluminum oxide template and copper film, thereby obtaining the roughened iron oxide nanotubes.

2. The preparation method according to claim 1, characterized in that, In step (b-2), the working electrode and the counter electrode are immersed in the electrolyte, stirred at a stirring rate of 200 r / min for 30 min and then the stirring is stopped. A salt bridge is used to connect the saturated KCl solution and the electrolyte for electrodeposition.

3. The preparation method according to claim 1, characterized in that, In step (d), the post-treatment solution is a 0.5-1.0 mol / L sodium hydroxide solution, and the soaking time is 50-70 min.

4. The preparation method according to claim 1, characterized in that, Step (a) specifically includes the following detailed process: (a-1) Primary oxidation: High-purity aluminum sheets that have undergone annealing and ultrasonic washing pretreatment are placed in an oxalic acid aqueous solution for primary anodizing to obtain primary aluminum oxide sheets with an oxide film formed on the surface; (a-2) Removal of primary oxide film: Take a primary alumina sheet, immerse it in a mixed aqueous solution of phosphoric acid and chromic acid, and then rinse it with water to obtain an aluminum sheet with the surface oxide film removed; (a-3) Secondary oxidation: The aluminum sheet with the surface oxide film removed is placed in an oxalic acid aqueous solution for secondary anodizing. During the oxidation process, the oxidation voltage gradually decreases. (a-4) Removing the substrate: Take out the aluminum sheet after secondary oxidation, wash it with water, then soak it in copper chloride solution, and then wash it clean with water; (a-5) Pore enlargement: The aluminum sheet without substrate is placed in a phosphoric acid aqueous solution to enlarge the pores, thereby obtaining anodized aluminum template with double nanopores.

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