FeOOH nanorod / reduced graphene oxide aerogel material and preparation method and application thereof

Abstract

The application belongs to the technical field of energy storage and conversion materials and its preparation, and particularly relates to a FeOOH nanorod / reduced graphene oxide aerogel material, a preparation method and application thereof. The application dissolves iron acetate tetrahydrate, urea, ascorbic acid and graphene oxide prepared by a Hummers' method in water to form a uniform mixed solution; then the mixed solution is loaded into a glass sample bottle, the bottle cap is screwed tightly, and the bottle is placed in an oven to react at a certain temperature to obtain a FeOOH / RGO composite hydrogel; and then the FeOOH / RGO composite hydrogel is freeze-dried to obtain a dried FeOOH / RGO aerogel. The prepared aerogel has a porous structure, the average length of the FeOOH nanorod is less than 10 nm, and the FeOOH nanorod is uniformly loaded on the surface of the graphene. The prepared aerogel has good capacitive performance and good application prospect in supercapacitors.

Description

Technical Field

[0001] This invention belongs to the field of energy storage and conversion materials and their preparation technology, specifically a FeOOH nanorod / reduced graphene oxide aerogel material, its preparation method, and its application. Background Technology

[0002] Supercapacitors are a novel type of energy storage device that falls between traditional electrolytic capacitors and secondary batteries. They possess significant advantages such as high power density, fast charge and discharge speeds, long cycle life, and high safety. These unique properties make them promising for applications in new energy vehicles, wind and solar power grid integration, rail transit energy recovery, smart grid frequency regulation, and portable electronic devices. However, the relatively low energy density of supercapacitors has always been a key bottleneck restricting their further large-scale application. Electrode materials are the core factor determining the performance of supercapacitors. Currently, commercial supercapacitors mainly use activated carbon with high specific surface area as the electrode material. Their energy storage mechanism is based on the double-layer capacitance of ion adsorption / desorption. Although they exhibit excellent power characteristics and cycle stability, their specific capacity is limited due to the physical adsorption energy storage mechanism, making it difficult to achieve a breakthrough in energy density. Therefore, developing novel electrode materials that combine high capacity, high rate performance, and good cycle stability has become a research hotspot in the field of supercapacitors.

[0003] To improve energy density, researchers have turned their attention to pseudocapacitive materials. Among them, iron hydroxyl oxide (FeOOH) has attracted much attention as a promising electrode material due to its high theoretical specific capacity, abundant resources, low cost, environmental friendliness, and the ability to undergo a reversible Faraday reaction within a specific potential window. However, the poor intrinsic conductivity of FeOOH severely limits its capacity utilization and practical application at high rates. Combining FeOOH with highly conductive carbon materials is an effective strategy to solve this problem. Studies have shown that loading FeOOH nanostructures onto porous carbon fibers or three-dimensional carbon frameworks through hydrothermal methods can significantly improve the electrochemical performance of the composite materials.

[0004] Graphene aerogel, a three-dimensional interconnected network structure material assembled from graphene sheets, not only inherits the advantages of graphene's high conductivity and high specific surface area, but its unique porous structure also provides a fast channel for ion transport and effectively buffers the volume expansion of electrode materials during charging and discharging. In recent years, functionalized graphene aerogels have demonstrated superior performance in supercapacitors. If the high capacity properties of FeOOH and the high conductivity and structural advantages of graphene aerogel can be fully utilized to construct a FeOOH nanorod / graphene aerogel composite material, it is expected to achieve a significant improvement in specific capacity and optimization of rate performance.

[0005] Currently, although there are reports on FeOOH composites with carbon materials, achieving uniform and controllable growth of FeOOH nanostructures on a three-dimensional graphene framework and forming stable interfacial bonds to maximize synergistic effects remains a technical challenge. Therefore, developing a simple and structurally controllable FeOOH nanorod / graphene aerogel composite material and its preparation method is of significant practical importance for obtaining high-energy-density and high-power-density supercapacitor electrode materials and promoting the development of supercapacitor technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a FeOOH nanorod / reduced graphene oxide aerogel material, its preparation method, and its application.

[0007] In this invention, ferric acetate tetrahydrate, urea, ascorbic acid, and graphene oxide prepared by Hummers' method are first dissolved in water to form a homogeneous mixture. The mixture is then placed in a glass sample vial, the cap is tightened, and the vial is placed in an oven for reaction at a specific temperature to obtain a FeOOH nanorod / reduced graphene oxide composite hydrogel. Finally, freeze-drying yields a dried FeOOH nanorod / reduced graphene oxide aerogel. The prepared aerogel has a porous structure, with FeOOH nanorods having an average length of less than 10 nm, uniformly loaded on the surface of reduced graphene oxide. The prepared aerogel exhibits excellent capacitance properties and shows promising application prospects in supercapacitors.

[0008] Technical solution: This invention discloses a method for preparing FeOOH nanorod / reduced graphene oxide aerogel material, the specific steps of which are as follows:

[0009] Step 1: Dissolve ferric acetate tetrahydrate, urea, ascorbic acid, and graphene oxide (GO) prepared by Hummers' method in water to form a homogeneous mixture;

[0010] Step 2: Pour the mixture prepared in Step 1 into a glass sample bottle, tighten the cap, and then place it in an oven to react at a certain temperature to obtain FeOOH nanorod / reduced graphene oxide composite hydrogel.

[0011] Step 3: Dry the composite hydrogel prepared in Step 2 to obtain dried FeOOH nanorod / reduced graphene oxide aerogel material.

[0012] Furthermore, in step two, the reaction temperature is 85~100 °C, and the reaction time is 4~8 h. Preferably, the reaction temperature is 95 °C, and the reaction time is 6 h.

[0013] Furthermore, in step three, the drying process is freeze-drying. The freeze-drying conditions are: cold trap temperature -55 °C, drying time 36 h.

[0014] Further, in step one, the mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is (0.5~2):(0.16~3.3):(1~3):(5~10):500. Preferably, in step one, the mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is 1:1.32:2:7.5:500.

[0015] The FeOOH nanorod / reduced graphene oxide aerogel material prepared by the above method is also within the scope of protection of this invention.

[0016] The application of the FeOOH nanorod / reduced graphene oxide aerogel material prepared by the above method in the preparation of flexible supercapacitors is also within the scope of protection of this invention.

[0017] Beneficial effects:

[0018] (1) This invention provides a new method for preparing FeOOH nanorod / reduced graphene oxide aerogel material. The prepared aerogel material has application prospects as a composite electrode material in energy storage and conversion. The FeOOH nanorod / reduced graphene oxide aerogel prepared by this invention has excellent capacitance performance and has good application prospects in supercapacitors.

[0019] (2) In this invention, by rationally designing the reaction conditions, the nucleation and growth of FeOOH nanorods on graphene oxide are carried out simultaneously with the reduction and self-assembly of graphene oxide, thereby obtaining a reduced graphene oxide hydrogel with FeOOH nanorods loaded on the surface in one step.

[0020] (3) The preparation method of the present invention has mild preparation conditions, simple and easy-to-control process, and the content of FeOOH in the composite material can be easily controlled by the amount of FeOOH precursor added.

[0021] (5) The microstructure and capacitance performance of the prepared FeOOH nanorod / reduced graphene oxide aerogel were studied, showing that the FeOOH nanorod / reduced graphene oxide aerogel prepared by the present invention has excellent capacitance performance. The specific capacitance at a current density of 1.0 A / g reaches 516.2 F / g, and the specific capacitance retention rate is 90.1% after 10,000 continuous charge-discharge cycles, which proves the good application prospects of the FeOOH nanorod / reduced graphene oxide aerogel provided by the present invention in supercapacitors. Attached Figure Description

[0022] Figure 1The images show the FeOOH nanorod / reduced graphene oxide (FeOOH / RGO) hydrogels prepared in Examples 1-5 of this invention and the reduced graphene oxide (RGO) hydrogel of Comparative Example 1.

[0023] Figure 2 The images are transmission electron microscope (TEM) images of the FeOOH / RGO aerogel prepared in Example 4 of the present invention and the RGO aerogel prepared in Comparative Example 1; wherein, a is a TEM image of the FeOOH / RGO aerogel prepared in Example 4, and b is a TEM image of the RGO aerogel prepared in Comparative Example 1.

[0024] Figure 3 The X-ray diffraction (XRD) spectra of the FeOOH / RGO aerogel prepared in Example 4 of this invention and the RGO aerogel prepared in Comparative Example 1 are shown.

[0025] Figure 4 The graph shows a comparison of the electrochemical performance of the FeOOH / RGO aerogel prepared in Example 4 of this invention with that of the RGO aerogel prepared in Comparative Example 1. In the graph, a is the cyclic voltammetry curve measured at a potential scan rate of 20 mV / s; b is the galvanostatic charge-discharge curve measured at a current density of 2 A / g; c is the specific capacitance-current density relationship curve; and d is the cycling performance of the FeOOH / RGO aerogel prepared in Example 4. Detailed Implementation

[0026] The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0027] Example 1:

[0028] A method for preparing FeOOH nanorod / reduced graphene oxide aerogel material includes the following steps:

[0029] Step (1): Disperse the graphene oxide prepared by Hummers' method in water, then add urea, ascorbic acid, and ferric acetate tetrahydrate, and stir to form a uniform mixture. The mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is 1:0.33:2:7.5:500.

[0030] Step (2): Pour the mixture prepared in step (1) into a glass sample bottle, tighten the cap, and then place it in an oven at 95°C. o After reacting at C for 6 h, FeOOH nanorods / reduced graphene oxide composite hydrogel was obtained.

[0031] Step (3): Freeze-dry the composite hydrogel prepared in step (2) to obtain dried FeOOH nanorod / reduced graphene oxide aerogel electrode material. Freeze dryer model: Shanghai Bilang FD-1A-50, cold trap temperature -55 °C, drying time 36 h.

[0032] The electrochemical performance of the prepared carbon foam material was determined using a CHI 660E electrochemical workstation. A three-electrode system was employed for electrochemical testing. The electrolyte was a 3 mol / L KOH solution. The reference electrode and counter electrode were Hg / HgO and a graphite rod, respectively. The working electrode was prepared by pressing the sample between two sheets of nickel foam under a pressure of 10 MPa using a tablet press. The specific capacitance of the carbon foam was calculated using the discharge time of a galvanostatic charge-discharge (GCD) curve. The specific capacitance was calculated using the formula: C = It / ΔV, where C (F / g) is the specific capacitance, I (A / g) is the current density, t (s) is the discharge time on the GCD curve, and ΔV (1.0 V) is the voltage window. At a current density of 1.0 A / g, the specific capacitance of the prepared FeOOH nanorod / reduced graphene oxide aerogel was 369.4 F / g.

[0033] Example 2:

[0034] A method for preparing FeOOH nanorod / reduced graphene oxide aerogel material includes the following steps:

[0035] Step (1): Disperse the graphene oxide prepared by Hummers' method in water, then add urea, ascorbic acid, and ferric acetate tetrahydrate, and stir to form a uniform mixture. The mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is 1:0.66:2:7.5:500.

[0036] Step (2): Pour the mixture prepared in step (1) into a glass sample bottle, tighten the cap, and then place it in an oven at 95°C. o After reacting at C for 6 h, FeOOH nanorods / reduced graphene oxide composite hydrogel was obtained.

[0037] Step (3): Freeze-dry the composite hydrogel prepared in step (2) to obtain dried α-FeOOH nanorod / reduced graphene oxide aerogel electrode material. Freeze dryer model: Shanghai Bilang FD-1A-50, cold trap temperature -55 °C, drying time 36 h.

[0038] At a current density of 1.0 A / g, the specific capacitance of the prepared FeOOH nanorod / reduced graphene oxide aerogel was 428.3 F / g.

[0039] Example 3:

[0040] A method for preparing FeOOH nanorod / reduced graphene oxide aerogel material includes the following steps:

[0041] Step (1): Disperse the graphene oxide prepared by Hummers' method in water, then add urea, ascorbic acid, and ferric acetate tetrahydrate, and stir to form a uniform mixture. The mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is 1:0.99:2:7.5:500.

[0042] Step (2): Pour the mixture prepared in step (1) into a glass sample bottle, tighten the cap, and then place it in an oven at 95°C. o After reacting at C for 6 h, FeOOH nanorods / reduced graphene oxide composite hydrogel was obtained.

[0043] Step (3): Freeze-dry the composite hydrogel prepared in step (2) to obtain dried FeOOH nanorod / reduced graphene oxide aerogel electrode material. Freeze dryer model: Shanghai Bilang FD-1A-50, cold trap temperature -55 °C, drying time 36 h.

[0044] At a current density of 1.0 A / g, the specific capacitance of the prepared FeOOH nanorod / reduced graphene oxide aerogel was 462.5 F / g.

[0045] Example 4:

[0046] A method for preparing FeOOH nanorod / reduced graphene oxide aerogel material includes the following steps:

[0047] Step (1): Disperse the graphene oxide prepared by Hummers' method in water, then add urea, ascorbic acid, and ferric acetate tetrahydrate, and stir to form a uniform mixture. The mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is 1:1.32:2:7.5:500.

[0048] Step (2): Pour the mixture prepared in step (1) into a glass sample bottle, tighten the cap, and then place it in an oven at 95°C. o After reacting at C for 6 h, FeOOH nanorods / reduced graphene oxide composite hydrogel was obtained.

[0049] Step (3): Freeze-dry the composite hydrogel prepared in step (2) to obtain dried FeOOH nanorod / reduced graphene oxide aerogel electrode material. Freeze dryer model: Shanghai Bilang FD-1A-50, cold trap temperature -55 °C, drying time 36 h.

[0050] At a current density of 1.0 A / g, the specific capacitance of the prepared FeOOH nanorod / reduced graphene oxide aerogel was 516.2 F / g.

[0051] Example 5:

[0052] A method for preparing FeOOH nanorod / reduced graphene oxide aerogel material includes the following steps:

[0053] (1) Disperse the graphene oxide prepared by Hummers' method in water, then add urea, ascorbic acid, and ferric acetate tetrahydrate, and stir to form a uniform mixture. The mass ratio of graphene oxide:ferric acetate tetrahydrate:ascorbic acid:urea:water is 1:2.64:2:7.5:500.

[0054] (2) Pour the mixture prepared in (1) into a glass sample bottle, tighten the cap, and then place it in an oven at 95°C. o After reacting at C for 6 h, FeOOH nanorods / reduced graphene oxide composite hydrogel was obtained.

[0055] (3) The composite hydrogel prepared in (2) was freeze-dried to obtain dried FeOOH nanorod / reduced graphene oxide aerogel electrode material. Freeze dryer model: Shanghai Bilang FD-1A-50, cold trap temperature -55 °C, drying time 36 h.

[0056] At a current density of 1.0 A / g, the specific capacitance of the prepared FeOOH nanorod / reduced graphene oxide aerogel was 503.1 F / g.

[0057] Comparative Example 1:

[0058] Reduced graphene oxide aerogel was prepared using a method similar to that in Example 1, including the following steps:

[0059] Step (1): Disperse the graphene oxide prepared by Hummers' method in water, then add urea and ascorbic acid, and stir to form a uniform mixture. The mass ratio of graphene oxide:ascorbic acid:urea:water is 1:2:7.5:500.

[0060] Step (2): Pour the mixture prepared in step (1) into a glass sample bottle, tighten the cap, and then place it in an oven at 95°C. o After reacting at C for 6 h, a reduced graphene oxide hydrogel was obtained.

[0061] Step (3): Freeze-dry the hydrogel prepared in step (2) to obtain dried reduced graphene oxide aerogel electrode material. Freeze dryer model: Shanghai Bilang FD-1A-50, cold trap temperature -55 °C, drying time 36 h.

[0062] At a current density of 1.0 A / g, the mass specific capacitance of the prepared reduced graphene oxide aerogel was 194.2 F / g.

[0063] Comparative Example 2:

[0064] FeOOH / RGO aerogels were prepared using a two-step method: first, an RGO hydrogel was prepared, and then FeOOH was loaded onto the RGO surface using the prepared RGO hydrogel as a carrier. The specific steps are as follows:

[0065] Step (1), Preparation of RGO hydrogel: Graphene oxide prepared by Hummers' method is dispersed in water, and ascorbic acid is added. A homogeneous mixture is formed under stirring. The mass ratio of graphene oxide:ascorbic acid:water is 1:2:500. The prepared mixture is poured into a glass sample bottle, the cap is tightened, and then the bottle is placed in an oven at 95°C. o After reacting at C for 6 h, a reduced graphene oxide hydrogel was obtained.

[0066] Step (2), Loading FeOOH onto RGO hydrogel: Prepare a mixed solution of ferric acetate and urea, with a mass ratio of ferric acetate:urea:water of 1.32:7.5:500; pour the above mixed solution into a glass sample bottle, immerse the reduced graphene oxide hydrogel prepared in step (1) in the mixed solution, tighten the cap of the glass sample bottle, and then place it in an oven at 95°C. o After reacting at C for 6 h, FeOOH / reduced graphene oxide hydrogel was obtained.

[0067] The FeOOH / reduced graphene oxide hydrogel prepared by the above two-step method exhibits a color difference from the outer surface to the interior, which can be observed with the naked eye. The outer surface of the hydrogel is light yellowish-brown, while the interior is black, gradually darkening from the outside to the inside, indicating that the FeOOH is not uniformly loaded on RGO. This is due to the bulk FeOOH content in the solution. 3+ Ions need to overcome resistance to diffuse into the hydrogel, causing Fe from the outer surface to the interior of the hydrogel to diffuse. 3+ The ion concentration gradually decreased, resulting in uneven loading of FeOOH on RGO. However, the FeOOH / RGO hydrogel prepared by the one-step method (Examples 1-5) exhibited uniform color throughout, and transmission electron microscopy revealed that FeOOH nanorods were uniformly dispersed on the RGO surface. This is due to the interaction between graphene oxide and FeOOH in the one-step reaction solution. 3+ The ions can be mixed uniformly, ensuring a uniform loading of FeOOH on the RGO surface.

[0068] Comparative Example 3:

[0069] In this comparative example, commonly used Fe-containing compounds such as FeCl3 and Fe2(NO3)3 are used. 3+ The effect of replacing ferric acetate with an ionic salt on the preparation was investigated.

[0070] Experiments revealed that the addition of FeCl3 and Fe2(NO3)3 caused graphene oxide to condense and precipitate from water. This is because FeCl3 and Fe2(NO3)3 are strong acid-weak base salts; their addition to water lowers the pH, leading to a reduction in the surface charge of the graphene oxide and subsequent condensation. Therefore, FeCl3 and Fe2(NO3)3 are unsuitable as precursors for the preparation of FeOOH / RGO hydrogels. Ferric acetate, on the other hand, is a weak acid-weak base salt; its addition to the reaction system does not cause a significant change in pH, and the reaction system remains stable.

[0071] Performance characterization:

[0072] 1. Figure 1 The images show the FeOOH nanorod / reduced graphene oxide (FeOOH / RGO) hydrogels prepared in Examples 1-5 of this invention and the reduced graphene oxide (RGO) hydrogel of Comparative Example 1.

[0073] like Figure 1 As shown, the hydrogels were placed in water. Due to the different FeOOH contents in each sample, the density of the FeOOH / RGO composite hydrogels varied. Examples 3, 4, and 5 had higher FeOOH contents, resulting in higher densities of the FeOOH / RGO composite hydrogels, which sank to the bottom. Examples 1 and 2 had lower FeOOH contents, resulting in lower densities of the FeOOH / RGO composite hydrogels, which floated on the surface. Comparative Example 1, a reduced graphene oxide hydrogel, also had a lower density and floated on the surface.

[0074] 2. The microstructure of the FeOOH nanorod / reduced graphene oxide (FeOOH / RGO) aerogel prepared in Example 4 and the reduced graphene oxide (RGO) aerogel prepared in Comparative Example 1 were characterized using transmission electron microscopy (TEM). The results are as follows: Figure 2 As shown, where Figure 2 Image a shows a TEM image of the RGO aerogel prepared in Comparative Example 1. Figure 2 Image b is a TEM image of the FeOOH / RGO aerogel prepared in Example 4; from Figure 2 As can be seen, the reduced graphene oxide in Comparative Example 1 is in the form of thin sheets with a clean surface. In contrast, the FeOOH / RGO aerogel prepared in Example 4 has a large number of nanoparticles on its surface, which are short rod-shaped with an average length of less than 10 nm. Furthermore, both FeOOH / RGO aerogel and RGO aerogel possess abundant porous structures. When used as electrode materials, the porous structure facilitates electrolyte transport and ion diffusion, contributing to improved electrochemical performance.

[0075] 3. The structures of the FeOOH / RGO aerogel prepared in Example 4 and the RGO aerogel prepared in Comparative Example 1 were characterized by X-ray diffraction (XRD), and the results are as follows: Figure 3 As shown. By Figure 3 As can be seen, the RGO aerogel prepared in Comparative Example 1 has two broad diffraction peaks, which are caused by the (002) and (100) planes of the graphite structure, respectively. The FeOOH / RGO aerogel prepared in Example 4, in addition to the diffraction peaks generated by RGO, also exhibits other sharp diffraction peaks. The positions and relative intensities of these diffraction peaks are consistent with the standard X-ray diffraction pattern of α-FeOOH (JPCDS no. 29-0713), proving that FeOOH nanorod / reduced graphene oxide aerogel was successfully prepared using the method of this invention.

[0076] 4. The electrochemical performance of the FeOOH / RGO aerogel prepared in Example 4 and the RGO aerogel prepared in Comparative Example 1 were characterized using a CHI660E electrochemical workstation. The cyclic voltammetry (CV) curves at a voltage scan rate of 20 mV / s and the galvanostatic charge-discharge (GCD) curves at a current density of 2 A / g are shown below. Figure 4 As shown, by Figure 4 As can be seen in Figure a, the CV curve of the RGO aerogel is approximately rectangular, exhibiting typical double-layer energy storage characteristics. In contrast, the FeOOH / RGO aerogel prepared in Example 4 shows a pair of redox peaks in its CV curve, exhibiting characteristics of a pseudocapacitive material. Correspondingly, the GCD curve of the RGO aerogel (…) Figure 4 In figure b), the curve is approximately isosceles triangular, while the GCD curve of FeOOH / RGO aerogel is distorted and deviates from linearity. This is due to the redox transition between Fe in different oxidation states during charge and discharge. Figure 4 As shown in the specific capacitance-current density curve in Figure c, the specific capacitance of FeOOH / RGO aerogel is higher than that of RGO aerogel at every current density. The FeOOH / RGO aerogel prepared in this invention also exhibits good cycling stability, such as... Figure 4 As shown in Figure d, after 10,000 charge-discharge cycles, the capacitance retention rate is 90.1%.

[0077] By combining Examples 1-5 and the comparative examples, the innovative points of this invention can be found as follows:

[0078] (1) Preparation method of FeOOH nanorods / reduced graphene oxide aerogel: By rationally designing the reaction conditions, the nucleation and growth of FeOOH on the graphene oxide surface are synchronized with the reduction and self-assembly of graphene oxide, ultimately obtaining FeOOH / RGO composite hydrogel. The preparation method of this invention is beneficial to the uniform distribution of FeOOH on the graphene surface. The preparation conditions of this invention are mild, the preparation process is simple and easy to control, and the content of FeOOH in the composite electrode material can be easily controlled by the amount of FeOOH precursor ferric acetate tetrahydrate added.

[0079] (2) Structure of FeOOH nanorods / reduced graphene oxide aerogel: FeOOH / RGO hydrogel was dried by freeze-drying. Due to the template effect of ice, the resulting FeOOH / RGO aerogel has a connected porous structure, which is beneficial for the diffusion of electrolyte ions when used as an electrode material, thus contributing to the improvement of electrochemical performance. The FeOOH nanorods prepared in this invention have an average length of less than 10 nm. The small size gives FeOOH a large specific surface area, which greatly improves the utilization rate of FeOOH. The small size also shortens the electron flow path and improves the conductivity of FeOOH. Combining the nanostructured FeOOH with highly conductive and porous RGO can form a synergistic effect, thereby improving the capacitance performance of the composite material.

[0080] In summary, this invention provides a novel method for preparing FeOOH nanorod / reduced graphene oxide aerogel. This method, through rationally designed reaction conditions, allows the nucleation and growth of FeOOH on graphene oxide to occur simultaneously with the reduction and self-assembly of graphene oxide, thus obtaining a FeOOH nanorod / reduced graphene oxide composite hydrogel in one step. The FeOOH nanorod / reduced graphene oxide aerogel obtained after freeze-drying combines the advantages of pseudocapacitive materials and electric double-layer capacitor materials. The synergistic effect of FeOOH and reduced graphene oxide gives the composite electrode material excellent capacitance performance, achieving a specific capacitance of 516.2 F / g at a current density of 1.0 A / g. After 10,000 cycles, the capacitance retention rate is 90.1%, showing promising application prospects in supercapacitors.

[0081] This invention provides a FeOOH nanorod / reduced graphene oxide aerogel, its preparation method, and its application. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing FeOOH nanorod / reduced graphene oxide aerogel material, characterized in that, The specific steps are as follows: Step 1: Disperse the graphene oxide prepared by Hummers' method in water, then add Fe... 3+ The salts of ions, urea, and ascorbic acid form a homogeneous mixture; Step 2: Pour the mixture prepared in Step 1 into a glass sample bottle, tighten the cap, and then place it in an oven to react at a certain temperature for a period of time to obtain FeOOH nanorod / reduced graphene oxide composite hydrogel. Step 3: Dry the composite hydrogel prepared in Step 2 to obtain dried FeOOH nanorod / reduced graphene oxide aerogel material.

2. The preparation method according to claim 1, characterized in that, In step one, it contains Fe 3+ The salt of the ion is ferric acetate tetrahydrate.

3. The preparation method according to claim 1, characterized in that, In step one, the mass ratio of graphene oxide: ferric acetate tetrahydrate: ascorbic acid: urea: water is (0.5~2): (0.16~3.3): (1~3): (5~10):

500.

4. The preparation method according to claim 3, characterized in that, In step one, the mass ratio of graphene oxide: ferric acetate tetrahydrate: ascorbic acid: urea: water is 1:1.32:2:7.5:

500.

5. The preparation method according to claim 1, characterized in that, In step two, the reaction temperature is 85~100℃. o C, reaction time 4~8 h.

6. The preparation method according to claim 5, characterized in that, In step two, the reaction temperature is 95℃ and the reaction time is 6 h.

7. The preparation method according to claim 1, characterized in that, In step three, the drying process is freeze drying.

8. The FeOOH nanorod / reduced graphene oxide aerogel material prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the FeOOH nanorod / reduced graphene oxide aerogel material as described in claim 8 in supercapacitors.

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