Graphene-metal oxide composite fiber as well as preparation method and application thereof

Abstract

The invention relates to the field of new material preparation, and discloses a graphene-metal oxide composite fiber as well as a preparation method and application thereof. The graphene-metal oxide composite fiber comprises a graphene fiber and a metal oxide loaded on the graphene fiber; the metal oxide is selected from one or more than two of oxides of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al; on the basis of the total weight of the graphene-metal oxide composite fiber, the loading capacity of the metal oxide is 0.05-5 wt%; the specific surface area of the graphene-metal oxide composite fiber is 80-150m < 2 > / g. The surface of the graphene-metal oxide composite fiber has a large number of wrinkles, the loading capacity of the metal oxide on the surface of the graphene fiber is high, and application of the graphene-metal oxide composite fiber in the aspects of gas sensing and the like is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of new material preparation, and in particular to a graphene-metal oxide composite fiber and a preparation method and application thereof. Background Art

[0002] In recent years, graphene has been widely used due to its excellent electrical conductivity (conductivity reaches 108S m -1 ), thermal conductivity (thermal conductivity can reach 5300W m -1 K -1 ), mechanical properties (Young's modulus reaches 1TPa) and large specific surface area (2630m 2 g -1 ), becoming one of the hot topics in the research of nano gas-sensitive materials.

[0003] Common graphene materials can be divided into one-dimensional nanofibers, two-dimensional nanofilms and three-dimensional graphene spheres according to their dimensions. One-dimensional graphene fibers have great development potential in the fields of energy, catalysis and sensing due to their good flexibility, conductivity and processability. However, pure-phase graphene fibers have a single surface structure and few functional groups, which limits their further application.

[0004] Nano-metal oxides include nano-iron oxide (Fe 2 O 3 ), cobalt tetraoxide (Co 3 O 4 ), tungsten trioxide (WO 3 ), molybdenum trioxide (MoO 3 ), copper oxide (CuO), zinc oxide (ZnO), etc., due to their unique crystal structure, morphology, composition, physical and chemical properties, etc., they are widely used in catalysis, energy storage, sensing and other fields, but their shortcomings of easy agglomeration and high resistance have a certain impact on their application. Combining one-dimensional graphene fibers with nano-metal oxides can achieve complementary advantages of the two, while further enhancing their performance and expanding their application range by utilizing heterojunctions and synergistic effects. However, in the graphene and metal oxide composites prepared so far, the metal oxide loading is low and unevenly distributed, which limits its further application.

[0005] In addition, there are two common methods for preparing one-dimensional graphene-metal oxide composite fibers. One is to directly add nano-metal oxides to the graphene oxide solution, and then obtain a one-dimensional structure by wet spinning or electrostatic spinning. The other is to immerse the graphene fiber in a metal oxide precursor solution and generate metal oxides on its surface by chemical reduction or hydrothermal reduction. In the former, the metal oxide and graphene are only connected by physical interaction, and the stability and electrochemical properties are poor. In the latter, the reaction conditions are demanding and it is only suitable for the composite of a small amount of metal oxides. At the same time, the method is complicated and not suitable for the preparation of large quantities of one-dimensional graphene-metal oxide composite fibers. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems existing in the prior art, such as the low metal oxide loading and uneven distribution in the graphene-metal oxide composite fiber, the complicated preparation method, and the harsh reaction conditions, and to provide a graphene-metal oxide composite fiber and a preparation method and application thereof. The surface of the graphene-metal oxide composite fiber has a large number of wrinkles, and the metal oxide is evenly loaded on the surface of the graphene fiber with a high loading, which is beneficial to the application of the graphene-metal oxide composite fiber in gas sensing, catalysis and energy storage.

[0007] In order to achieve the above-mentioned object, the present invention provides a graphene-metal oxide composite fiber on one hand, wherein the graphene-metal oxide composite fiber comprises a graphene fiber and a metal oxide supported on the graphene fiber;

[0008] The metal oxide is selected from one or more of the oxides of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al;

[0009] The specific surface area of ​​the graphene-metal oxide composite fiber is 80-150m 2 / g;

[0010] Based on the total weight of the graphene-metal oxide composite fiber, the loading amount of the metal oxide is 0.05-5wt%.

[0011] Preferably, the metal oxide is selected from one or more of Zn, Cu, Co, Fe and Mn.

[0012] A second aspect of the present invention provides a method for preparing a graphene-metal oxide composite fiber, the method comprising the following steps:

[0013] (1) mixing alginate, graphene oxide and water to obtain a mixed dispersion;

[0014] (2) mixing the mixed dispersion with a solution containing calcium ions to obtain graphene oxide hydrogel fibers;

[0015] (3) Immersing the graphene oxide hydrogel fiber in a metal salt solution and then sintering it.

[0016] Preferably, the weight ratio of graphene oxide, alginate and metal salt is 1:0.8-10:5-50, wherein the weight of the metal salt is calculated as metal element.

[0017] Preferably, in the mixed dispersion, the mass concentration of the alginate is 0.01-5%;

[0018] Preferably, in the mixed dispersion, the concentration of the graphene is 1-15 mg / mL.

[0019] Preferably, the mass concentration of calcium ions in the solution containing calcium ions is 1-10%.

[0020] Preferably, in step (2), the mixed dispersion is mixed with a solution containing calcium ions using a microinjection pump;

[0021] Preferably, the flow rate of the microinjection pump is 0.05-0.15 mL / min.

[0022] Preferably, the concentration of the metal salt in the metal salt solution is 0.05-0.2 mol / L.

[0023] Preferably, in step (1), the mixing method is ultrasonic mixing;

[0024] Preferably, the power of ultrasonic mixing is 100-500 W, and the time of ultrasonic mixing is 10-120 min.

[0025] Preferably, the heating temperature is 60-100°C.

[0026] Preferably, in step (3), the graphene oxide hydrogel fiber is wound on a roller and immersed in a metal salt solution.

[0027] Preferably, the sintering conditions include: a temperature of 200-700° C. and a time of 1-4 hours.

[0028] Preferably, the atmosphere during sintering is an inert atmosphere.

[0029] The third aspect of the present invention provides a graphene-metal oxide composite fiber prepared by the above method.

[0030] A fourth aspect of the present invention provides an application of the above-mentioned graphene-metal oxide composite fiber in the field of gas sensing, catalysis or energy storage.

[0031] The surface of the graphene-metal oxide composite fiber described in the present invention has a large number of wrinkles and a large specific surface area, which provides more metal oxide loading sites, and the metal oxide is evenly dispersed on the surface of the graphene fiber. In addition, in the graphene-metal oxide composite fiber described in the present invention, the loading amount of the metal oxide is large, and the metal oxide and the graphene fiber are tightly combined, which is conducive to its application in gas sensing, catalysis and energy storage fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a surface morphology image of the graphene-ZnO composite fiber prepared in Example 1 of the present invention;

[0033] Figure 2 The graphene-CO prepared in Example 2 of the present invention 3 O 4 Surface morphology of composite fibers;

[0034] Figure 3 The graphene-Fe prepared in Example 3 of the present invention 2 O 3 Surface morphology of composite fibers;

[0035] Figure 4 This is the surface morphology of pure graphene oxide. DETAILED DESCRIPTION

[0036] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0037] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0038] The graphene-metal oxide composite fiber of the present invention comprises a graphene fiber and a metal oxide supported on the graphene fiber. In the present invention, the metal in the metal oxide can be a divalent metal and / or a trivalent metal, and the valence state of the metal element can be +2 and / or +3.

[0039] In a specific embodiment, the metal oxide is selected from one or more of the oxides of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al.

[0040] In the present invention, there are a large number of wrinkles on the surface of the graphene fiber, which increases the specific surface area of ​​the graphene-metal oxide composite fiber. In addition, the metal oxide is evenly distributed on the surface of the graphene fiber and has a large loading capacity, so that the performance of the metal oxide in subsequent applications is increased. The specific surface area of ​​the graphene-metal oxide composite fiber is 80-150m 2 / g. Specifically, the specific surface area of ​​the graphene-metal oxide composite fiber can be 80m 2 / g, 90m 2 / g、100m 2 / g, 110m 2 / g, 120m 2 / g, 130m 2 / g, 140m 2 / g or 150m 2 / g.

[0041] In the present invention, based on the total weight of the graphene-metal oxide composite fiber, the loading amount of the metal oxide is 0.05-5wt%, preferably 2.8-4wt%.

[0042] In a preferred embodiment, in order to further improve the performance of the graphene-metal oxide composite fiber and reduce its preparation cost and facilitate its better application, the metal oxide is selected from one or more of Zn, Cu, Co, Fe and Mn.

[0043] The present invention also provides a method for preparing graphene-metal oxide composite fibers, the method comprising the following steps:

[0044] (1) mixing alginate, graphene oxide and water to obtain a mixed dispersion;

[0045] (2) mixing the mixed dispersion with a solution containing calcium ions to obtain graphene oxide hydrogel fibers;

[0046] (3) Immersing the graphene oxide hydrogel fiber in a metal salt solution and then sintering it.

[0047] In a specific embodiment, the process of step (1) includes: mixing graphene oxide with water to obtain a graphene oxide dispersion, and then mixing sodium alginate with the graphene oxide dispersion to obtain a mixed dispersion.

[0048] In the present invention, due to the addition of alginate, the viscosity of the material obtained by mixing alginate and graphene oxide dispersion increases, thereby avoiding the agglomeration of graphene oxide caused by the addition of alginate. In step (1), ultrasonic mixing is used to evenly disperse the material obtained by mixing graphene oxide and alginate, and the graphene oxide sheets are completely peeled off to obtain a single-layer graphene sheet, thereby further increasing the specific surface area of ​​the prepared graphene-metal oxide composite fiber.

[0049] In a preferred embodiment, in order to facilitate better dispersion of graphene oxide, the power of the ultrasonic mixing is controlled to be 100-500 W, preferably 200-400 W, and the time of the ultrasonic mixing is 10-120 min, preferably 20-50 min.

[0050] In the present invention, in step (1), the solubility of alginate in water is increased by heating, so that the alginate is completely dissolved and the agglomeration of graphene oxide is prevented. Preferably, the heating temperature is 60-100° C. In the present invention, the heating time is not limited, and it only needs to be heated until the added alginate is completely dissolved, for example, it can be 3-5 hours.

[0051] In the present invention, the alginate may be a commercially available alginate product commonly found in the art, for example, sodium alginate and / or potassium alginate.

[0052] In the present invention, alginate is added to the graphene oxide dispersion to improve the viscosity and strength of the mixed dispersion, thereby preventing deformation due to too low strength during the subsequent preparation of graphene oxide hydrogel fibers, thereby affecting the morphology and specific surface area of ​​the obtained graphene-metal oxide composite fibers, thereby affecting the performance of the product.

[0053] In a preferred embodiment, in the mixed dispersion, the mass concentration of the alginate is 0.01-5%, preferably 1-3%. Specifically, the mass concentration of the alginate can be 1%, 1.5%, 2%, 2.5% or 3%.

[0054] In a preferred embodiment, in the mixed dispersion, the concentration of the graphene oxide is 1-15 mg / mL, preferably 3-10 mg / mL. Specifically, the concentration of the graphene oxide can be 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL or 8 mg / mL.

[0055] In the present invention, in step (2), the mixed dispersion is mixed with a solution containing calcium ions for cross-linking, and the calcium ions in the solution react with the negative ions on the graphene oxide and the alginate to perform physical cross-linking, thereby combining the graphene oxide and the alginate to prepare graphene oxide hydrogel fibers.

[0056] In a preferred embodiment, the mass concentration of calcium ions in the solution containing calcium ions is 1-10%. When the concentration of calcium ions in the solution containing calcium ions is too low, the strength of the prepared graphene oxide hydrogel fiber will be too low. However, when the concentration of calcium ions is too high, the residual calcium-containing substances in the prepared graphene oxide hydrogel fiber will be too much, thereby affecting the structure and performance of the graphene-metal oxide composite fiber prepared subsequently. Specifically, the mass concentration of calcium ions in the solution containing calcium ions can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0057] In a specific embodiment, the solution containing calcium ions can be a calcium chloride solution, a calcium nitrate solution or a calcium sulfate solution.

[0058] In a preferred embodiment, in step (2), in order to ensure the morphology of the obtained graphene oxide hydrogel fibers, a microinjection pump can be used to inject the mixed dispersion into a solution containing calcium ions to form uniform graphene oxide hydrogel fibers.

[0059] In a preferred embodiment, the flow rate of the microinjection pump is controlled to be 0.05-0.15 mL / min. Specifically, the flow rate of the microinjection pump can be 0.05 mL / min, 0.1 mL / min or 0.15 mL / min.

[0060] In the present invention, when the graphene oxide hydrogel fiber is immersed in the metal salt solution, the volume of the metal salt solution used is not limited, and it is only necessary to ensure that the graphene oxide hydrogel fiber is completely immersed in the metal salt solution.

[0061] In a specific embodiment, the metal salt is selected from one or more of salts of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al.

[0062] In a specific embodiment, in step (3), the soaking time is 10-15 hours.

[0063] In the present invention, the soaking temperature in step (3) is not limited, and can be, for example, room temperature 25°C.

[0064] In the present invention, after the graphene oxide hydrogel fiber is prepared in step (2), solid-liquid separation is performed, and the graphene oxide hydrogel fiber is taken out and directly immersed in a metal salt solution. When the graphene oxide hydrogel fiber is dried and then immersed in a metal salt solution, it will lead to problems such as low subsequent metal oxide loading.

[0065] In a preferred embodiment, in order to make the graphene oxide hydrogel fiber soaked more fully in the metal salt solution in step (3), the graphene oxide hydrogel fiber can be wound on a roller and soaked in the metal salt solution. In addition, winding the graphene oxide hydrogel fiber on a roller and soaking it is also conducive to facilitating the collection of the fiber and the drying of subsequent products.

[0066] In a preferred embodiment, in order to further improve the performance of the prepared graphene-metal oxide composite fiber, the weight ratio of graphene oxide, alginate and metal salt is 1:0.8-10:5-50, preferably 1:1-5:6-30, wherein the weight of the metal salt is calculated as the metal element.

[0067] In a preferred embodiment, the concentration of the metal salt in the metal salt solution is 0.05-0.2 mol / L. Specifically, the concentration of the metal salt may be 0.05 mol / L, 0.08 mol / L, 0.1 mol / L, 0.15 mol / L or 0.2 mol / L.

[0068] In the present invention, sodium alginate and graphene oxide are combined to form graphene oxide hydrogel fibers. When the graphene oxide hydrogel fibers are immersed in a metal salt solution, the adsorption amount of the metal salt is increased, and the adsorbed metal salt is more evenly distributed on the fiber surface. The composite fiber finally obtained has higher strength and better performance.

[0069] In the present invention, the sodium alginate in the material can be removed by sintering the soaked material. In addition, the graphene oxide can be reduced to further improve its conductivity and electrical properties, and a metal oxide structure with a more stable crystal form can be obtained.

[0070] In a preferred embodiment, in order to further improve the performance of the graphene-metal oxide composite fiber, the sintering temperature is controlled to be 200-700° C., preferably 300-600° C.; and the sintering time is 1-4 hours.

[0071] In the present invention, when the sintering temperature is too high, the metal oxide and graphene will undergo a carbon thermal reaction, and the graphene will react to generate CO. 2, resulting in a reduction in the carbon content in the final product and more carbon defects, which is not conducive to improving the performance of the graphene-metal oxide composite fiber. When the sintering temperature is too low, the metal salt precursor cannot be effectively decomposed to produce metal oxides, resulting in too little content of metal oxides.

[0072] In a specific embodiment, in step (3), the sintering atmosphere is an inert atmosphere, which can be a nitrogen atmosphere, an argon atmosphere or an argon atmosphere.

[0073] The present invention further provides a graphene-metal oxide composite fiber prepared by the above method.

[0074] In the present invention, the added alginate is cross-linked with graphene oxide to obtain graphene oxide hydrogel fibers. Although alginate exists therein, in the subsequent sintering process, due to the small molecular weight of alginate and the low carbonization rate, the residual carbon after high-temperature sintering is very small and can be ignored.

[0075] The present invention also provides an application of the graphene-metal oxide composite fiber in the field of gas sensing, catalysis or energy storage.

[0076] The graphene-metal oxide composite fiber described in the present invention has a large specific surface area and high strength performance, and the graphene-metal oxide composite fiber has a higher metal oxide loading capacity. When applied to the fields of gas sensing, catalysis and active energy storage, it can provide more active sites and adsorption sites, thereby improving the performance of the material.

[0077] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0078] Example 1

[0079] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.1 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely exfoliate the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 300 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 1%).

[0080] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 mL / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0081] (3) The graphene oxide hydrogel fiber is immersed in 200mL of zinc nitrate aqueous solution (the concentration of zinc nitrate is 0.1mol / L, the weight ratio of graphene oxide, sodium alginate and zinc nitrate is 1:2:26.152, and the weight of zinc nitrate is calculated as zinc element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 500°C, the sintering time is 2 hours, and after sintering, a graphene-ZnO composite fiber is obtained. After thermal gravimetric test, it can be seen that the content of ZnO in the graphene-ZnO composite fiber is 3.8wt%.

[0082] Example 2

[0083] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.2 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely exfoliate the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 200 W and the ultrasonic time was 40 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 2%).

[0084] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 mL / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0085] (3) The graphene oxide hydrogel fiber is immersed in 200 mL of cobalt nitrate aqueous solution (the concentration of cobalt nitrate is 0.1 mol / L, the weight ratio of graphene oxide, sodium alginate and cobalt nitrate is 1:4:23.6, where the weight of cobalt nitrate is calculated as cobalt element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 600°C, the sintering time is 2 hours, and after sintering, graphene-Co 3 O 4 Composite fiber. After thermal gravimetric testing, it is known that graphene-Co 3 O 4 Co in composite fiber 3 O 4 The content is 2.7wt%.

[0086] Example 3

[0087] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.1 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion, so that the graphene oxide sheets were completely peeled off and evenly dispersed in water, the ultrasonic power was 350 W, and the ultrasonic time was 35 min; then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 1%);

[0088] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 mL / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0089] (3) The graphene oxide hydrogel fiber is immersed in 200 mL of ferric nitrate aqueous solution (the concentration of ferric nitrate is 0.1 mol / L, the weight ratio of graphene oxide, sodium alginate and ferric nitrate is 1:2:22.32, and the weight of ferric nitrate is calculated as iron element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then, the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 400°C, the sintering time is 2 hours, and after sintering, graphene-Fe 2 O 3 Composite fiber. After thermal gravimetric testing, it is known that graphene-Fe 2 O 3 Fe in composite fiber 2 O 3 The content is 2.9wt%.

[0090] Example 4

[0091] (1) 100 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.1 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely exfoliate the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 300 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 10 mg / mL and the mass concentration of sodium alginate was 0.5%).

[0092] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 mL / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0093] (3) Immerse the graphene oxide hydrogel fiber uniformly into a mixed solution of 200 mL of an aqueous ferric nitrate solution and an aqueous cobalt nitrate solution (the concentrations of ferric nitrate and cobalt nitrate are both 0.2 mol / L, the molar ratio of ferric nitrate to cobalt nitrate is 10:1, and the dosage ratio of graphene oxide, sodium alginate, and the total weight of ferric nitrate and cobalt nitrate is 1:1:22.68, where the total weight of ferric nitrate and cobalt nitrate is calculated based on iron and cobalt elements), soak it, and wind it onto a roller for 12 h. Then dry the soaked graphene oxide hydrogel fiber in an oven at 80 °C for 24 h, and then place it in a tube furnace for sintering in a nitrogen atmosphere; the sintering temperature is 550 °C, the sintering time is 2 h, and after sintering, a graphene-Fe 2 O 3 / Co 3 O 4 composite fiber is obtained. Through thermogravimetric detection, it can be known that the content of Fe 2 O 3 / Co 3 O 4 in the graphene-Fe 2 O 3 / Co 3 O 4 composite fiber is 3.1 wt%.

[0094] Example 5

[0095] (1) Disperse 100 mg of graphene oxide in 10 mL of deionized water to obtain a graphene oxide dispersion, and then add 0.1 g of sodium alginate to the graphene oxide dispersion for ultrasonic dispersion to completely exfoliate the graphene oxide sheets and uniformly disperse them in water. The ultrasonic power is 400 W, and the ultrasonic time is 25 min; then heat it at 70 °C for 4 h to obtain a mixed dispersion (where the concentration of graphene oxide is 10 mg / mL and the mass concentration of sodium alginate is 1%);

[0096] (2) Add the mixed dispersion to a micro-injection pump, control the flow rate of the micro-injection pump to be 0.1 mL / min, and uniformly inject the mixed dispersion into an aqueous calcium chloride solution (the mass concentration of calcium chloride is 5%) to form a graphene oxide hydrogel fiber;

[0097] (3) The graphene oxide hydrogel fiber is immersed in a mixed solution of 200 mL of an aqueous solution of iron nitrate and an aqueous solution of copper nitrate at a uniform speed (the concentration of iron nitrate and copper nitrate is 0.06 mol / L, the molar ratio of iron nitrate to copper nitrate is 1:1, and the total weight ratio of graphene oxide, sodium alginate and iron nitrate to copper nitrate is 1:1:7.163, wherein the total weight of iron nitrate and copper nitrate is calculated as iron and copper elements), and then wound onto a roller and immersed for 12 hours. The immersed graphene oxide hydrogel fiber is then dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 600°C, the sintering time is 2 hours, and after sintering, graphene-Fe 2 O 3 / CuO composite fiber. Thermogravimetric test shows that graphene-Fe 2 O 3 Fe / CuO composite fiber 2 O 3 / CuO content is 3.5wt%.

[0098] Example 6

[0099] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.1 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely peel off the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 400 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 1%).

[0100] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 mL / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0101] (3) The graphene oxide hydrogel fiber is immersed in 200mL of zinc nitrate aqueous solution (the concentration of zinc nitrate is 0.1mol / L, the weight ratio of graphene oxide, sodium alginate and zinc nitrate is 1:2:26.152, and the weight of zinc nitrate is calculated as zinc element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then, the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 700°C, the sintering time is 2 hours, and after sintering, a graphene-ZnO composite fiber is obtained. After thermal gravimetric detection, it can be seen that the content of ZnO in the graphene-ZnO composite fiber is 3.4wt%.

[0102] Example 7

[0103] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.1 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely peel off the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 400 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 1%).

[0104] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 ml / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0105] (3) The graphene oxide hydrogel fiber is immersed in 200mL of zinc nitrate aqueous solution (the concentration of zinc nitrate is 0.1mol / L, the weight ratio of graphene oxide, sodium alginate and zinc nitrate is 1:2:26.152, and the weight of zinc nitrate is calculated as zinc element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then, the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 650°C, the sintering time is 2 hours, and after sintering, a graphene-ZnO composite fiber is obtained. After thermal gravimetric detection, it can be seen that the content of ZnO in the graphene-ZnO composite fiber is 3.1wt%.

[0106] Example 8

[0107] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 0.1 g of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely peel off the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 400 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 1%).

[0108] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 ml / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0109] (3) The graphene oxide hydrogel fiber is immersed in 200mL of zinc nitrate aqueous solution (the concentration of zinc nitrate is 0.1mol / L, the weight ratio of graphene oxide, sodium alginate and zinc nitrate is 1:2:26.152, and the weight of zinc nitrate is calculated as zinc element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then, the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 250°C, the sintering time is 2 hours, and after sintering, a graphene-ZnO composite fiber is obtained. After thermal gravimetric detection, it can be seen that the content of ZnO in the graphene-ZnO composite fiber is 2.6wt%.

[0110] Example 9

[0111] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 350 mg of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely exfoliate the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 300 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 3.3%).

[0112] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 ml / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0113] (3) The graphene oxide hydrogel fiber is immersed in 200mL of zinc nitrate aqueous solution (the concentration of zinc nitrate is 0.1mol / L, the weight ratio of graphene oxide, sodium alginate and zinc nitrate is 1:7:26.152, and the weight of zinc nitrate is calculated as zinc element) at a uniform speed, and then wound on a roller and soaked for 12 hours. Then, the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 500°C, the sintering time is 2 hours, and after sintering, a graphene-ZnO composite fiber is obtained. After thermal gravimetric detection, it can be seen that the content of ZnO in the graphene-ZnO composite fiber is 4.2wt%.

[0114] Example 10

[0115] (1) 50 mg of graphene oxide was dispersed in 10 mL of deionized water to obtain a graphene oxide dispersion, and then 40 mg of sodium alginate was added to the graphene oxide dispersion for ultrasonic dispersion to completely exfoliate the graphene oxide sheets and evenly disperse them in water. The ultrasonic power was 300 W and the ultrasonic time was 30 min. The mixture was then heated at 70° C. for 4 h to obtain a mixed dispersion (wherein the concentration of graphene oxide was 5 mg / mL and the mass concentration of sodium alginate was 0.4%).

[0116] (2) adding the mixed dispersion into a microinjection pump, controlling the flow rate of the microinjection pump to 0.1 ml / min, and uniformly injecting the mixed dispersion into a calcium chloride aqueous solution (the mass concentration of calcium chloride is 5%) to form graphene oxide hydrogel fibers;

[0117] (3) The graphene oxide hydrogel fiber is immersed in 200mL of zinc nitrate aqueous solution (the concentration of zinc nitrate is 0.1mol / L, the weight ratio of graphene oxide, sodium alginate and zinc nitrate is 1:0.8:26.152, where the weight of zinc nitrate is calculated as zinc element) at a uniform speed, and is wound on a roller and soaked for 12 hours. Then the soaked graphene oxide hydrogel fiber is dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature is 500°C, the sintering time is 2 hours, and after sintering, a graphene-ZnO composite fiber is obtained. After thermal gravimetric detection, it can be seen that the content of ZnO in the graphene-ZnO composite fiber is 1.8wt%.

[0118] Comparative Example 1

[0119] The method of Example 1 was followed, except that the zinc nitrate aqueous solution was replaced with an equal volume of nano ZnO dispersion, wherein the weight of the nano ZnO was equal to the weight of the zinc nitrate. Thermogravimetric test showed that the content of ZnO in the graphene-ZnO composite fiber was 0.046wt%.

[0120] Comparative Example 2

[0121] The method of Example 1 was used, except that the mixed dispersion in step (1) and the zinc nitrate aqueous solution in step (3) were mixed evenly and allowed to stand for 12 h, and then the obtained mixed solution was added to a microinjection pump, the flow rate of the microinjection pump was controlled to be 0.1 mL / min, and the mixed solution was evenly injected into a calcium chloride aqueous solution (the mass concentration of calcium chloride was 5%). Graphene fibers could not be formed, and only a graphene dispersion was obtained. The final product was in powder form.

[0122] Thermogravimetric analysis showed that the content of ZnO in the graphene-ZnO composite powder was 0.028 wt%.

[0123] Comparative Example 3

[0124] The preparation was carried out according to the method of Example 1, except that sodium alginate was not added in step (1), and in step (2), the graphene oxide dispersion was directly injected into the calcium chloride aqueous solution to prepare the graphene-ZnO composite fiber.

[0125] Thermogravimetric analysis showed that the content of ZnO in the graphene-ZnO composite fiber was 0.031 wt%.

[0126] Comparative Example 4

[0127] The preparation was carried out according to the method of Example 1, except that the graphene oxide hydrogel fiber was immersed in 200 mL of zinc nitrate aqueous solution (the concentration of zinc nitrate was 0.1 mol / L) at a uniform speed, and then placed in a hydrothermal kettle for hydrothermal reaction at 180°C for 24 hours. It was then dried in an oven at 80°C for 24 hours, and then placed in a tubular furnace for sintering in a nitrogen atmosphere; the sintering temperature was 500°C, the sintering time was 2 hours, and after the sintering was completed, a graphene-ZnO composite fiber was obtained.

[0128] Thermogravimetric analysis showed that the content of ZnO in the graphene / ZnO composite fiber was 6.7 wt%.

[0129] Test Case

[0130] Test Example 1

[0131] The morphology of the products prepared in Examples 1-3 and graphene oxide was tested using a scanning electron microscope. The results are as follows: Figures 1 to 4 shown.

[0132] Figure 1 The surface morphology of the graphene-ZnO composite fiber prepared in Example 1 is shown in FIG. Figure 1 It can be seen that the graphene surface has many wrinkles, which come from the stacking that occurs during the reduction of graphene oxide. At the same time, there are particles of about 10nm evenly distributed on the surface. These particles are nano-ZnO, and the distribution of nano-ZnO is even.

[0133] Figure 2 The graphene-Co prepared in Example 2 3 O 4 Surface morphology of composite fibers. Figure 2 It can be seen that nanoparticles with a particle size of about 10 nm are also distributed on the surface of graphene fibers. These particles are Co 3 O 4 Particles, and Co 3 O 4 The particles are evenly distributed on the surface of graphene fibers.

[0134] Figure 3 The graphene-Fe prepared in Example 3 2 O 3 Surface morphology of composite fibers. Figure 2 It can be seen that nanoparticles with a particle size of about 10 nm are also distributed on the surface of graphene fibers. These particles are Fe 2 O 3 Particles, and Fe 2 O 3 The particles are evenly distributed on the surface of graphene fibers.

[0135] Figure 4 is the surface morphology of pure graphene oxide. Figure 4 It can be seen that the surface of graphene oxide is smooth, without the loading of nanoparticles, and without too many wrinkles. It can be seen that the carrier graphene fiber in the graphene-metal oxide composite fiber prepared by the present invention has a larger specific surface area and can provide more active sites.

[0136] Test Example 2

[0137] The specific surface areas of the products prepared in Examples 1-10 and Comparative Examples 1-4 were tested using BET. The results are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141] It can be seen from the results in Table 1 that the graphene-metal oxide composite fiber of the present invention can have both a large specific surface area and a high metal oxide loading, and can be well applied in the fields of gas sensing, catalysis and energy storage.

[0142] Test Example 3

[0143] The products prepared in Examples 1-10 and Comparative Examples 1-4 were installed as gas-sensitive materials in hydrogen sulfide gas sensors to detect hydrogen sulfide gas, and the response values ​​of the prepared hydrogen sulfide gas sensors to hydrogen sulfide gas were tested.

[0144] Test method: Place the hydrogen sulfide gas sensor in a sealed cavity, apply working voltage to the hydrogen sulfide gas sensor, then introduce hydrogen sulfide gas (the concentration of hydrogen sulfide is 10ppm), and measure its response value to hydrogen sulfide. During the test, the response value of the hydrogen sulfide gas sensor S (Sensitivity) = (R x -R 0 ) / R 0 , where R0 is the resistance value of the hydrogen sulfide gas sensor in the air, R x is the resistance value of the hydrogen sulfide gas sensor after hydrogen sulfide gas is introduced. The test results are shown in Table 2.

[0145] Table 2

[0146]

[0147]

[0148] According to the results in Table 2, the graphene-metal oxide composite fiber of the present invention has high sensitivity to hydrogen sulfide gas and can be well used as a gas-sensitive material in the field of gas sensing. In addition, the preparation method is simple and has great industrial application prospects.

[0149] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A graphene-metal oxide composite fiber, It is characterized in that The graphene-metal oxide composite fiber comprises graphene fiber and metal oxide supported on the graphene fiber; The metal oxide is selected from one or more of the oxides of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al; The specific surface area of ​​the graphene-metal oxide composite fiber is 80-150m 2 / g; Based on the total weight of the graphene-metal oxide composite fiber, the loading amount of the metal oxide is 0.05-5wt%.

2. The graphene-metal oxide composite fiber according to claim 1, It is characterized in that The metal oxide is selected from one or more of Zn, Cu, Co, Fe and Mn.

3. A method for preparing graphene-metal oxide composite fibers, It is characterized in that The method comprises the following steps: (1) mixing alginate, graphene oxide and water to obtain a mixed dispersion; (2) mixing the mixed dispersion with a solution containing calcium ions to obtain graphene oxide hydrogel fibers; (3) soaking the graphene oxide hydrogel fiber in a metal salt solution and then sintering it; The metal salt is selected from one or more of salts of Zn, Cd, Cu, Ni, Pd, Pt, Co, Ir, Fe, Mn, Cr, Mo, W, V, Ti, Mg and Al.

4. The method according to claim 3, It is characterized in that The weight ratio of graphene oxide, alginate and metal salt is 1:0.8-10:5-50, wherein the weight of the metal salt is calculated as metal element.

5. The method according to claim 3 or 4, It is characterized in that In the mixed dispersion, the mass concentration of the alginate is 0.01-5%; Preferably, in the mixed dispersion, the concentration of graphene oxide is 1-15 mg / mL.

6. The method according to claim 3, It is characterized in that The mass concentration of calcium ions in the solution containing calcium ions is 1-10%.

7. The method according to claim 3, It is characterized in that In step (2), the mixed dispersion is mixed with a solution containing calcium ions using a microinjection pump; Preferably, the flow rate of the microinjection pump is 0.05-0.15 mL / min.

8. The method according to claim 3 or 4, It is characterized in that The concentration of the metal salt in the metal salt solution is 0.05-0.2 mol / L.

9. The method according to claim 3, It is characterized in that In step (1), the mixing method is ultrasonic mixing; Preferably, the power of ultrasonic mixing is 100-500 W, and the time of ultrasonic mixing is 10-120 min.

10. The method according to claim 3, It is characterized in that The sintering conditions include: temperature of 200-700° C. and time of 1-4 hours.

11. The method according to claim 3 or 10, It is characterized in that The atmosphere during the sintering is an inert atmosphere.

12. The method according to claim 3, It is characterized in that In step (3), the graphene oxide hydrogel fiber is wound on a roller and immersed in a metal salt solution.

13. Graphene-metal oxide composite fiber prepared according to the method according to any one of claims 3 to 12.

14. Use of the graphene-metal oxide composite fiber according to any one of claims 1 to 2 or the graphene-metal oxide composite fiber according to claim 13 in the field of gas sensing, catalysis or energy storage.

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