Iron molybdate nanorod material, nitrogen-doped carbon-coated iron molybdate nanorod material as well as preparation method and application of iron molybdate nanorod material and nitrogen-doped carbon-coated iron molybdate nanorod material

Abstract

The invention provides an iron molybdate nanorod material, a nitrogen-doped carbon-coated iron molybdate nanorod material and a preparation method and application thereof, and belongs to the technical field of nanomaterials, MoO3 nanorods, ferric iron salt, ferrous iron salt and sodium acetate are used as raw materials, and the Fe2 (MoO4) 3 nanorod material is controllably prepared through one-step hydrothermal treatment and calcination. The material has an excellent sensitive characteristic to hydrogen sulfide gas; a Fe2 (MoO4) 3 nanorod material is further subjected to nitrogen-doped carbon coating, the nitrogen-doped carbon-coated iron molybdate nanorod material is prepared, the material can well relieve an active substance structure collapse phenomenon caused by volume expansion in a battery negative electrode charging and discharging process, and a nitrogen-doped carbon layer can improve the conductivity of the composite material and accelerate transmission of lithium ions and electrons, so that the performance of a lithium ion battery is improved, and the service life of the lithium ion battery is prolonged. Therefore, the rate capability and the cycle performance of the lithium ion battery are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterials, and particularly relates to a ferromolybdate nanorod material, a nitrogen-doped carbon-coated ferromolybdate nanorod material, and a preparation method and application thereof. BACKGROUND

[0002] In recent years, gas sensors have been increasingly widely applied in the fields of environmental monitoring, industrial safety, medical diagnosis, etc. Gas sensors based on semiconductor metal oxides have become a research hotspot due to their low cost, simple preparation process, fast response speed, high stability, etc. However, traditional metal oxide sensors still face challenges such as insufficient selectivity, high working temperature, high detection limit, etc., and it is urgent to improve their sensing performance through material structure design and performance optimization.

[0003] Fe2(MoO4)3 is a typical n-type semiconductor material with a band gap of 2.8 eV. Due to its excellent chemical stability and rich redox active sites, it has broad application prospects in the fields of photocatalysis, lithium ion batteries, supercapacitors, and gas sensing. Studies have shown that the microstructure of metal oxides has a significant impact on their physical and chemical properties, such as size, crystal orientation, aspect ratio, etc. For example, one-dimensional nanostructures (such as nanorods, nanowires) can effectively enhance the exposure of surface active sites, promote gas molecule adsorption and reaction kinetics, and significantly improve the gas sensing performance due to their high specific surface area, anisotropic charge transport characteristics, and structural stability.

[0004] Currently, researchers have successfully prepared ferromolybdate nanoparticles, nanosheets, and porous microspheres through various strategies such as hydrothermal method, solvothermal method, and electrospinning. However, their application in gas sensing is still limited by low sensitivity and low selectivity. In addition, non-spherical complex structures (such as nanorod arrays, core-shell structures) can further optimize the electronic structure and surface activity of materials through heterojunction engineering and morphology control, thereby improving the sensing performance. However, how to construct ferromolybdate nanomaterials with hierarchical structure through simple and controllable synthesis strategies is still a difficult problem to be solved.

[0005] In addition, the negative electrode materials of lithium ion batteries mainly include carbon materials, silicon-based and composite materials, metal oxides, and metal sulfides, etc. The metal oxide materials have the advantages of abundant resources and high theoretical capacity, and are the negative electrode materials with a good application prospect. However, the structure instability and low conductivity of the metal oxide materials result in poor actual performance. Iron molybdate is a widely used semiconductor material, and has good stability and environmental friendliness compared with other metal compounds. However, when used as the negative electrode of a lithium ion battery, the iron molybdate electrode will experience a large volume expansion in the process of lithium ion insertion and extraction, resulting in the destruction of the structure of the electrode material and the pulverization of the electrode material, and thus affecting the cycle stability of the battery. In addition, the poor conductivity of the iron molybdate limits the improvement of the rate performance. These problems seriously restrict the wide application of iron molybdate as the negative electrode material of a lithium ion battery. SUMMARY

[0006] To solve the above technical problems, the application provides a preparation method of Fe2(MoO4)3 nanorod material, which realizes the precise construction of one-dimensional nanostructure through controllable hydrothermal synthesis and calcination process, solves the problems of low specific surface area and limited gas diffusion of traditional Fe2(MoO4)3 material, and significantly improves the sensitive performance of the material to H2S and other gases, thereby providing a new material basis for the development of high-performance gas sensors.

[0007] The application also provides the application of the Fe2(MoO4)3 nanorod material in a gas sensor, which has a high sensitive response to H2S gas and good stability.

[0008] The application also provides a nitrogen-doped carbon-coated iron molybdate nanorod material and a preparation method thereof. The material can well alleviate the structure collapse phenomenon of active substances caused by volume expansion during the charging and discharging process of the battery negative electrode. The nitrogen-doped carbon layer can improve the conductivity of the composite material and accelerate the transmission of lithium ions and electrons, thereby improving the rate performance and cycle performance of the lithium ion battery.

[0009] The application also provides a lithium battery negative electrode prepared by taking the nitrogen-doped carbon-coated iron molybdate nanorod material as the active substance.

[0010] The application also provides a lithium battery assembled by taking the lithium battery negative electrode as the negative electrode, and the battery has good rate performance and cycle performance.

[0011] The technical solutions adopted by the application are as follows.

[0012] The application provides a preparation method of Fe2(MoO4)3 nanorod material, and the preparation method comprises the following steps.

[0013] (1) Disperse MoO3 nanorods, ferric salts, ferrous salts and sodium acetate in deionized water and perform hydrothermal reaction at 100~200℃ for 6~24 h;

[0014] (2) The product obtained in step (1) is calcined at 350~550℃ for 1~6 h to obtain Fe2(MoO4)3 nanorods.

[0015] In step (1), the Fe in the MoO3 nanorods and ferric salts 3+ Fe in ferrous salts 2+ The molar ratio of sodium acetate is 3:1:1:5~10; the concentration of MoO3 nanorods in deionized water is 30~80 g / L, preferably 50~65 g / L.

[0016] The trivalent ferric salt is one or more of ferric sulfate nonahydrate, ferric nitrate nonahydrate, and ferric chloride hexahydrate; the divalent ferric salt is one or more of ferrous sulfate heptahydrate, ferrous ammonium sulfate hexahydrate, and ferrous chloride tetrahydrate.

[0017] In step (1), the hydrothermal reaction is preferably carried out at 120~150℃ for 12~18 h.

[0018] In step (2), the preferred calcination conditions are calcination at 450~500℃ for 2~3 h.

[0019] The present invention also provides the application of the Fe2(MoO4)3 nanorod material in a gas sensor, which has a high sensitivity response to H2S gas and good stability.

[0020] This invention also provides a method for preparing nitrogen-doped carbon-coated iron molybdate nanorods, the method comprising the following steps:

[0021] 1) The Fe2(MoO4)3 nanorod material prepared in this invention is dispersed in deionized water, tris(hydroxymethyl)aminomethane is added, and the pH of the solution is adjusted to 7-10 with acid. Then dopamine hydrochloride is added, and the reaction is stirred for 12-30 h.

[0022] 2) The product obtained in step 1) is heat-treated under the protection of an inert gas.

[0023] In step 1), the mass ratio of Fe2(MoO4)3 nanorod material, tris(hydroxymethyl)aminomethane, and dopamine hydrochloride is 1:0.2~0.4:0.2~0.9, preferably 1:0.2~0.3:0.35~0.55; the concentration of Fe2(MoO4)3 nanorod material in deionized water is 5~50 g / L, preferably 25~35 g / L.

[0024] In step 1), the temperature of the stirring reaction is 5~40℃, preferably 15~30℃; the stirring reaction time is preferably 18~24 h.

[0025] In step 2), the heat treatment conditions are: 350~550℃ for 2~10 h, preferably 400~500℃ for 4~6 h.

[0026] In step 2), the inert gas is nitrogen.

[0027] The present invention also provides a lithium battery anode, wherein the lithium battery anode is prepared using the nitrogen-doped carbon-coated iron molybdate nanorod material described in the present invention as the active material.

[0028] This invention also provides a lithium battery, which is assembled using the lithium battery negative electrode described in this invention as the negative electrode. This battery exhibits good cycle stability at a current density of 0.2 Ah g. −1 Even after 500 cycles, the battery capacity still reaches 825 mAh g. −1 .

[0029] The present invention provides a method for preparing Fe2(MoO4)3 nanorod materials. Using MoO3 nanorods, ferric salts, ferrous salts, and sodium acetate as raw materials, Fe2(MoO4)3 nanorod materials can be controlled to be prepared through a one-step hydrothermal and calcination process. The reaction that occurs in this process is as follows: 9MoO3 + 2Fe 3+ + 4Fe 2+ + 7H2O + O2 → 3Fe2(MoO4)3 + 14H + This material exhibits excellent sensitivity to hydrogen sulfide gas, primarily due to its large specific surface area resulting from its nanorod structure, which effectively increases gas adsorption. The rod-shaped structure forms a sensitive membrane with numerous gas transport channels, facilitating rapid gas diffusion and transfer. Its unique one-dimensional nanostructure enhances internal electron transport efficiency, accelerating the response speed. Furthermore, abundant surface active sites provide more opportunities for adsorption and catalytic reactions. This invention opens up new directions for the development of gas sensor materials, providing a novel solution for the high-sensitivity and high-selectivity detection of hydrogen sulfide gas, and is expected to further promote the development of gas sensing technology in environmental monitoring, industrial safety detection, and other fields.

[0030] The application provides a preparation method of nitrogen-doped carbon-coated iron molybdate nanorod material.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] 1. The Fe2(MoO4)3 nanorod material and the nitrogen-doped carbon-coated iron molybdate nanorod material prepared by the application have high purity, are in nanorod structure, and have uniform nanorod diameter distribution; the preparation process is simple, the conditions are mild, raw materials are cheap and easy to obtain, the cost is low, and batch production can be carried out.

[0033] 2. The Fe2(MoO4)3 nanorod material prepared by the application has good stability, high temperature resistance and large specific surface area, so that the detected gas is fully adsorbed on the outer surface of the material, gas transmission is accelerated, and sensitive performance is improved.

[0034] 3. The Fe2(MoO4)3 nanorod material prepared by the application has high sensitivity, rapid response and high stability when used as a semiconductor gas sensor for hydrogen sulfide gas.

[0035] 4. The nitrogen-doped carbon-coated iron molybdate nanorod material provided by the application has a large contact area with electrolyte when used as an active substance of a lithium battery negative electrode, is beneficial to electron and lithium ion transmission, and has excellent electrochemical performance due to the one-dimensional nanometer structure which can buffer the volume change of the active material in the charging and discharging process. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The SEM image of the MoO3 nanorod material;

[0037] Figure 2 The XRD image of the MoO3 nanorod material;

[0038] Figure 3 The SEM image of the Fe2(MoO4)3 nanorod material prepared in Example 1;

[0039] Figure 4 The SEM image of the NC@Fe2(MoO4)3 nanorod material prepared in Example 1;

[0040] Figure 5 SEM image of Fe2(Mo04)3nanorod material prepared for Example 2;

[0041] Figure 6 SEM image of NC@Fe2(Mo04)3nanorod material prepared for Example 2;

[0042] Figure 7 SEM image of Fe2(Mo04)3nanorod material prepared for Example 3;

[0043] Figure 8 XRD image of Fe2(Mo04)3nanorod material prepared for Example 3;

[0044] Figure 9 Elemental mapping of Fe2(Mo04)3nanorod material prepared for Example 3;

[0045] Figure 10 SEM image of NC@Fe2(Mo04)3nanorod material prepared for Example 3;

[0046] Figure 11 TEM image of NC@Fe2(Mo04)3nanorod material prepared for Example 3;

[0047] Figure 12 XRD image of NC@Fe2(Mo04)3nanorod material prepared for Example 3;

[0048] Figure 13 Elemental mapping of NC@Fe2(Mo04)3nanorod material prepared for Example 3;

[0049] Figure 14 SEM image of Fe2(Mo04)3nanorod material prepared for Example 4;

[0050] Figure 15 SEM image of NC@Fe2(Mo04)3nanorod material prepared for Example 4;

[0051] Figure 16 SEM image of Fe2(Mo04)3nanorod material prepared for Example 5;

[0052] Figure 17 SEM image of NC@Fe2(Mo04)3nanorod material prepared for Example 5;

[0053] Figure 18The response sensitivity of the gas sensor prepared by using the Fe2(MoO4)3 nanorod material in Example 3 as a working electrode to 10 ppm of hydrogen sulfide gas and 100 ppm of 7 kinds of organic gases and ammonia gas at a working temperature of 80℃;

[0054] Figure 19 The cycle stability test results of the lithium battery prepared by using the NC@Fe2(MoO4)3 nanorod material in Example 3 as a negative active material at a current density of 0.2 A g −1 DETAILED DESCRIPTION

[0055] The application will be described in detail below with reference to the examples.

[0056] The preparation method of the MoO3 nanorod material in each example is as follows:

[0057] 2.9 g of ammonium molybdate tetrahydrate and 1.3 g of aspartic acid were dispersed in 16 mL of deionized water, 5 mL of 4 mol / L nitric acid solution was added thereto, and after being uniformly mixed, hydrothermal reaction was carried out at 180℃ for 20 h. After cooling, the product was filtered, washed and dried to obtain MoO3 white powder. The SEM image thereof is shown in Figure 1 , and it can be seen from the image that it is a nanorod. The XRD thereof is shown in Figure 2 . The MoO3 nanorod material prepared by any other method can also be used as the molybdenum trioxide nanorod in the application.

[0058] Example 1

[0059] The preparation method of the iron molybdate nanorod material and the nitrogen-doped carbon-coated iron molybdate nanorod material comprises the following steps:

[0060] (1) Preparation of the iron molybdate nanorod material: 0.3 g of MoO3 nanorod material, 0.188 g of iron trichloride hexahydrate, 0.193 g of ferrous sulfate heptahydrate and 0.473 g of sodium acetate trihydrate were sequentially added to 10 ml of deionized water, and stirred to mix them uniformly. The mixture was transferred to a polytetrafluoroethylene reaction kettle, and hydrothermal reaction was carried out at 200℃ for 6 h. After the reaction was completed, the product was filtered, washed with deionized water and dried at 50℃. Finally, the dried product was placed in a muffle furnace, and heated to 350℃ at a heating rate of 7 ℃ / min, and calcined for 6 h to obtain the Fe2(MoO4)3 nanorod material. The SEM image thereof is shown in Figure 3 .

[0061] ​(2) Preparation of the nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material: 0.25 g of the Fe2(MoO4)3 nanorod material was ultrasonically dispersed in 50 mL of deionized water, 0.1 g of tris-hydroxymethyl aminomethane was added, the pH of the solution was adjusted to 7.0 with a hydrochloric acid solution, 0.225 g of dopamine hydrochloride was further added, and the reaction was stirred at 5°C for 30 h. The product was collected, washed with deionized water by centrifugation for 3 times, and dried at 40°C under vacuum for 24 h. Then the obtained product was heat-treated at 350°C under high-purity nitrogen for 10 h, and naturally cooled to room temperature to obtain the nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material (NC@Fe2(MoO4)3), the SEM of which is shown in FIG. 2. Figure 4

[0062] Example 2

[0063] The preparation method of the iron molybdate nanorod material and the nitrogen-doped carbon-coated iron molybdate nanorod material comprises the following steps:

[0064] (1) Preparation of the iron molybdate nanorod material: 0.5 g of MoO3 nanorod material, 0.313 g of iron trichloride hexahydrate, 0.322 g of ferrous sulfate heptahydrate, and 0.987 g of sodium acetate trihydrate were sequentially added into 10 mL of deionized water, and stirred to mix uniformly. The mixture was transferred into a polytetrafluoroethylene reaction kettle, and hydrothermally reacted at 180°C for 8 h. After the reaction was completed, the product was washed with deionized water and dried at 60°C. Finally, the dried product was placed into a muffle furnace, and heated to 420°C at a heating rate of 6°C / min, and calcined for 4 h to obtain the Fe2(MoO4)3 nanorod material, the SEM of which is shown in FIG. 1. Figure 5

[0065] (2) Preparation of the nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material: 0.5 g of the Fe2(MoO4)3 nanorod material was ultrasonically dispersed in 50 mL of deionized water, 0.2 g of tris-hydroxymethyl aminomethane was added, the pH of the solution was adjusted to 8 with a hydrochloric acid, 0.375 g of dopamine hydrochloride was further added, and the reaction was stirred at 15°C for 26 h. The product was collected, washed with deionized water by centrifugation for 3 times, and dried at 45°C under vacuum for 24 h. Then the obtained product was heat-treated at 400°C under high-purity nitrogen for 8 h, and naturally cooled to room temperature to obtain the NC@Fe2(MoO4)3 nanorod composite material, the SEM of which is shown in FIG. 3. Figure 6

[0066] Example 3

[0067] The iron molybdate nanorod material, the nitrogen-doped carbon-coated iron molybdate nanorod material, and the preparation method thereof, comprise the following steps:

[0068] ​​​(1) Preparation of iron molybdate nanorod material: 0.6 g of MoO3 nanorod material, 0.390 g of iron sulfate nonahydrate, 0.545 g of ferrous ammonium sulfate hexahydrate, and 1.33 g of sodium acetate trihydrate were sequentially added to 10 ml of deionized water, stirred to mix thoroughly, and then transferred to a polytetrafluoroethylene reactor for hydrothermal reaction at 150°C for 18 h. After the reaction, the product was washed with deionized water and dried at 70°C. Finally, the dried product was placed in a muffle furnace and calcined at 450°C for 2 h at a heating rate of 5°C / min to obtain the Fe2(MoO4)3 nanorod material. The SEM image thereof is shown in FIG. 1, and it can be seen that the product is a one-dimensional nanorod structure. The XRD thereof is shown in FIG. 2, and it can be found that all the diffraction peaks match Fe2(MoO4)3 (JCPDS No. 31-0642) and no other impurity peaks are present. The elemental distribution map of the product is shown in FIG. 3, and it can be seen that Fe, Mo, and O are relatively uniformly distributed in the Fe2(MoO4)3 material, and the Fe2(MoO4)3 sample has good consistency and uniformity in the microstructure. Figure 7 Figure 8 Figure 9

[0069] (2) Preparation of nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material: 1.2 g of Fe2(MoO4)3 nanorod material was ultrasonically dispersed in 50 mL of deionized water, 0.3 g of tris-hydroxymethyl aminomethane was added, the pH of the solution was adjusted to 8.5 with hydrochloric acid, 0.55 g of dopamine hydrochloride was added, and the mixture was stirred at 20°C for 22 h. The product was collected, washed with deionized water by centrifugation for 3 times, and dried at 50°C under vacuum for 20 h. Then the obtained product was heat-treated at 450°C for 6 h under high-purity nitrogen, and naturally cooled to room temperature to obtain the NC@Fe2(MoO4)3 nanorod composite material. The SEM, TEM, XRD, and elemental distribution map thereof are shown in FIGS. 4, 5, 6, and 7, respectively. Figures 10-13

[0070] Example 4

[0071] An iron molybdate nanorod material, a nitrogen-doped carbon-coated iron molybdate nanorod material, and a preparation method thereof, comprising the following steps:

[0072] ​​​​(1) Preparation of iron molybdate nanorod material: 0.7 g of MoO3 nanorod material, 0.455 g of iron sulfate nonahydrate, 0.635 g of ferrous ammonium sulfate hexahydrate and 1.69 g of sodium acetate trihydrate were sequentially added to 10 ml of deionized water, stirred to fully mix, and the mixture was transferred to a polytetrafluoroethylene reaction kettle for hydrothermal reaction at 120°C for 20 h. After the reaction was completed, the product was washed with deionized water and dried at 80°C. Finally, the dried product was placed in a muffle furnace and calcined at a temperature of 500°C at a heating rate of 4 ℃ / min for 1.5 h to obtain the iron molybdate nanorod material. The SEM image thereof is shown in FIG. 1. Figure 14

[0073] (2) Preparation of nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material: 1.8 g of Fe2(MoO4)3 nanorod material was ultrasonically dispersed in 50 mL of deionized water, 0.4 g of tris-hydroxymethyl aminomethane was added, the pH of the solution was adjusted to 9 with hydrochloric acid, 0.72 g of dopamine hydrochloride was added, and the reaction was stirred at 25°C for 18 h. The product was collected, washed with deionized water by centrifugation 3 times, and vacuum dried at 70°C for 15 h. Then the obtained product was heat-treated at 500°C for 4 h under high-purity nitrogen, and naturally cooled to room temperature to obtain the NC@Fe2(MoO4)3 nanorod composite material. The SEM thereof is shown in FIG. 2. Figure 15

[0074] Example 5

[0075] An iron molybdate nanorod material, a nitrogen-doped carbon-coated iron molybdate nanorod material and a preparation method thereof, comprising the following steps:

[0076] (1) Preparation of iron molybdate nanorod material: 0.8 g of MoO3 nanorod material, 0.748 g of iron nitrate nonahydrate, 0.368 g of ferrous chloride tetrahydrate and 2.515 g of sodium acetate trihydrate were sequentially added to 10 ml of deionized water, stirred to fully mix, and the mixture was transferred to a polytetrafluoroethylene reaction kettle for hydrothermal reaction at 100°C for 24 h. After the reaction was completed, the product was washed with deionized water and dried at 90°C. Finally, the dried product was placed in a muffle furnace and calcined at a temperature of 550°C at a heating rate of 3 ℃ / min for 1 h to obtain the iron molybdate nanorod material. The SEM image thereof is shown in FIG. 3. Figure 16

[0077] ​​​(2) Preparation of nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material: 2.5 g of Fe2(MoO4)3 nanorod material was ultrasonically dispersed in 50 mL of deionized water, 0.5 g of tris-hydroxymethyl aminomethane was added, the pH of the solution was adjusted to 10 with hydrochloric acid, 0.5 g of hydrochloric acid dopamine was added, and the reaction was stirred at 40 °C for 12 h. The product was collected, washed with deionized water by centrifugation for 3 times, and dried at 80 °C under vacuum for 12 h. Then the obtained product was heat-treated at 550 °C under high-purity nitrogen for 2 h, and naturally cooled to room temperature to obtain NC@Fe2(MoO4)3 nanorod composite material, and the SEM image thereof is shown in FIG. 6. Figure 17

[0078] Application Example 1

[0079] Application of Fe2(MoO4)3 nanorod material in gas sensor

[0080] Fe2(MoO4)3 nanorod material prepared in Example 3 was dispersed in anhydrous ethanol, and then uniformly coated on a ceramic tube with an electrode to make a gas sensor, which was dried at 50 °C for 2 h, and then heat-treated at 200 °C for 2 h. Then, a small nickel-chromium alloy coil was put into the tube as a heater for providing working temperature for the sensor, and the sensor was aged at 250 °C for 48 h, and then tested at working temperature for different volatile organic gases. The specific testing operation steps were as follows: a certain amount of organic vapor was injected into the sensor test box by a syringe, and after waiting for about 2 minutes, the output response value of the sensor was stable, and then dry air was introduced into the test box, and the output response of the sensor gradually recovered. The output response values of the sensor in dry air and in the target gas were tested and recorded by an electrochemical workstation and a computer. The response sensitivity of the sensor to the gas was defined as S = R a / R g (Reductant gas), R a is the resistance of the sensor in dry air, and R g is the resistance of the sensor in the test gas.

[0081] Figure 18 The response sensitivity of the sensor prepared by using Fe2(MoO4)3 nanorod material in Example 3 to 10 ppm H2S and 100 ppm different types of VOCs (including ethanol, isopropyl alcohol, acetone, benzene, toluene, n-butanol, methanol and ammonia, etc.) at a working temperature of 90 °C.

[0082] The experimental results show that the Fe2(MoO4)3 nanorod material prepared in Example 3 has a good sensitive response to common toxic and harmful organic gases in air. For example, Figure 18 ​As shown in the figure, the Fe2(MoO4)3 nanorod material prepared by the method has good selectivity to hydrogen sulfide among different VOCs (including ethanol, isopropyl alcohol, acetone, benzene, toluene, n-butanol, methanol and ammonia, etc.), and thus can be used as a sensitive material for H2S gas to realize high-sensitivity detection of H2S gas.

[0083] Application Example 2

[0084] Application of the NC@Fe2(MoO4)3 nanorod material in a lithium ion battery negative electrode:

[0085] The NC@Fe2(MoO4)3 nanorod material prepared in Example 3 was used as a negative electrode active material of a lithium ion battery. The active material was mixed with acetylene black and polyvinylidene fluoride (PVDF) at a ratio of 7:2:1, and was uniformly stirred with N-methyl pyrrolidone (NMP) as a solvent to form a uniform paste. The paste was coated on a copper foil, and the prepared coating was transferred to an oven and dried at 60°C for 6 h. Then, the sample was transferred to a vacuum drying oven and vacuum dried at 60°C for 12 h. The composite coating was rolled and cut into pieces. A lithium sheet was used as a counter electrode, a commercially available 1M LiPF6 / EC + DMC solution was used as an electrolyte, and a polypropylene film (Celgard 240) was used as a battery separator. The battery was assembled in an argon atmosphere.

[0086] Finally, the charge-discharge performance of the battery was tested by a battery tester. The lithium ion battery negative electrode material obtained had a cycle stability of 825 mAh g-1 at 0.2 A g-1 after 500 cycles. −1 The cycle stability test results of the lithium ion battery negative electrode material at different current densities are shown in FIG. 6. Figure 19 As shown in the figure, the lithium battery prepared by using the nitrogen-doped carbon-coated Fe2(MoO4)3 nanorod material as a negative electrode active material has good cycle stability, and the battery capacity is still as high as 825 mAh g-1 after 500 cycles. −1 .

[0087] The above detailed description of the molybdate nanorod material, the nitrogen-doped carbon-coated molybdate nanorod material, the preparation method and the application thereof in the above reference examples is illustrative rather than limiting, and a number of examples can be listed within the limited range, and thus changes and modifications without departing from the overall concept of the present application shall fall within the protection scope of the present application.

Claims

1. A method for preparing Fe2(MoO4)3 nanorod material, characterized in that, The preparation method comprises the following steps: (1) dispersing MoO3 nanorods, ferric salt, ferrous salt and sodium acetate into deionized water, and carrying out hydrothermal reaction at 100-200 ℃ for 6-24 h; (2) calcining the product obtained in step (1) at 350-550 ℃ for 1-6 h to obtain Fe2(MoO4)3 nanorods.

2. The method for preparing Fe2(MoO4)3 nanorod material according to claim 1, characterized in that, In step (1), the molar ratio of MoO3nanorods, Fe in the trivalent iron salt 3+ , Fe in the divalent iron salt 2+ , sodium acetate is 3:1:1:5-10; the concentration of MoO3nanorods in deionized water is 30-80 g / L.

3. The method for preparing Fe2(MoO4)3 nanorod material according to claim 1 or 2, characterized in that, The ferric salt is one or more of ferric sulfate nonahydrate, ferric nitrate nonahydrate and ferric chloride hexahydrate; and the ferrous salt is one or more of ferrous sulfate heptahydrate, ferrous ammonium sulfate hexahydrate and ferrous chloride tetrahydrate.

4. Application of the Fe2(MoO4)3 nanorod material prepared by the preparation method of claim 1 or 2 to a gas sensor.

5. A method for preparing nitrogen-doped carbon-coated iron molybdate nanorod material, characterized in that, The preparation method comprises the following steps: 1) dispersing the Fe2(MoO4)3 nanorod material prepared by the preparation method of any one of claims 1-3 into deionized water, adding tris-hydroxymethyl aminomethane, adjusting the pH of the solution to 7-10 with an acid, then adding dopamine hydrochloride, and stirring for 12-30 h; 2) subjecting the product obtained in step 1) to heat treatment under the protection of an inert gas. 6.The method of claim 5, wherein the method further comprises the step of: adding a molybdenum source to the mixture of claim 5. In step 1), the mass ratio of the Fe2(MoO4)3 nanorod material, tris-hydroxymethyl aminomethane and dopamine hydrochloride is 1:0.2-0.4:0.2-0.9; and the concentration of the Fe2(MoO4)3 nanorod material in the deionized water is 5-50 g / L.

7. The method for preparing nitrogen-doped carbon-coated iron molybdate nanorods according to claim 5, characterized in that, In step 2), the heat treatment is carried out at 350-550 ℃ for 2-10 h.

8. The nitrogen-doped carbon-coated iron molybdate nanorod material prepared by the preparation method of any one of claims 5-7.

9. A lithium battery anode, characterized by, The lithium battery negative electrode is prepared by using the nitrogen-doped carbon-coated iron molybdate nanorod material of claim 8 as an active material.

10. A lithium battery, characterized by, The lithium battery is assembled by using the lithium battery negative electrode of claim 9 as a negative electrode.

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