Molybdenum-doped chromium CoMo1-yCryO4.( H2O) 0.75 material as well as preparation method and application of molybdenum-doped chromium CoMo1-yCryO4.( H2O) 0.75 material

Abstract

The invention discloses a preparation method of a molybdenum-doped chromium element CoMo (1-y) CryO4. (H2O) 0.75 material, and belongs to the field of inorganic materials. The preparation method comprises the following steps: dissolving cobalt nitrate hexahydrate, ammonium molybdate tetrahydrate, ammonium fluoride and potassium dichromate in purified water, carrying out constant-temperature reaction in a hydrothermal reaction kettle, filtering, drying a product in a drying oven, calcining in a muffle furnace, and cooling to obtain the CoMo (1-y) CryO4. (H2O) 0.75 material. According to the method, the electrochemical performance is improved by doping the chromium element metal at the molybdenum site, the coexistence of split cells and a rod-like form is observed in the microscopic form, and the surface of the form is full of wrinkles, so that the specific surface area of the material can be well increased, the contact area with an electrolyte is increased, and the active sites of the reaction are improved.

Description

Technical Field

[0001] The present invention discloses a cobalt molybdate 1-y Cr y O4·(H2O) 0.75 material, its preparation method and application, belonging to the technical field of supercapacitors in inorganic materials. Background Art

[0002] With the rapid development of human society and the progress of technology, the dependence on traditional fossil fuels such as oil has become increasingly obvious. This not only causes significant pollution to the environment but also accelerates the process of global warming. Therefore, the international community has paid more and more attention to the optimization of the energy structure, actively promoting the development and application of clean energy in order to reduce the dependence on fossil fuels and alleviate the impact of climate change to a certain extent. Clean energy, such as solar energy and wind energy, has become an important development direction in the energy field due to its renewable and low-pollution characteristics. However, these renewable energies have obvious limitations, that is, they are restricted by region and time, which leads to the instability and intermittency of solar and wind energy in power supply and cannot ensure continuous and stable energy output.

[0003] To overcome the above problems and achieve the efficient utilization of clean energy, a supporting energy storage system is particularly important. Energy storage technology can not only balance the problem of supply-demand mismatch but also store excess energy during low demand and release it during high demand, thus realizing the stable supply of energy, which plays a key role in maintaining the stability of the power grid and increasing the application proportion of clean energy. As a new energy storage technology, supercapacitors have received extensive attention in the energy storage field due to their advantages such as high power density, fast charge-discharge ability, and long service life. With the popularization of clean energy and the development of energy storage technology, supercapacitors play an increasingly important role in modern energy systems. It can not only support the stable output of renewable energy but also provide an efficient energy storage solution for electric vehicles, promoting the further application and development of green technologies. Therefore, it is urgent to modify supercapacitor materials to improve the stability and specific capacitance of supercapacitors. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a cobalt molybdate 1-y Cr y O4·(H2O) 0.75 material. Cobalt nitrate hexahydrate, ammonium molybdate tetrahydrate, ammonium fluoride, and potassium dichromate are successively added to pure water and stirred evenly. After the mixed solution is stirred sufficiently, it is put into a hydrothermal reaction kettle and reacted at a constant temperature in an oven. After the reaction is completed, the reaction product is taken out and washed, and then dried at a constant temperature and put into a muffle furnace for calcination at a constant temperature. After cooling with the furnace, this material is obtained. This synthesis method is simple and low-cost, and is suitable for large-scale industrial production.

[0005] The cobalt molybdenum (CoMo) with chromium element doped at the molybdenum site according to the present invention 1-y Cr y O4·(H2O) 0.75 Material: This material coexists in a rod-like structure and a split-cell-like structure. In XRD, 2θ is 9.8°, 13.5°, 29.5°, 32.9°; the peaks in XPS appear at 796.59 eV, 780.68 eV, 234.71 eV, 231.58 eV; the valence state of the Mo element is +6; y = 0.01, 0.02, 0.03, 0.05.

[0006] The cobalt molybdenum (CoMo) with chromium element doped at the molybdenum site according to the present invention 1-y Cr y O4·(H2O) 0.75 Preparation method of the material, comprising the following steps:

[0007] First step, disperse cobalt nitrate hexahydrate in deionized water, add ammonium molybdate tetrahydrate and ammonium fluoride, and stir evenly;

[0008] Second step, add potassium dichromate, stir evenly, then place the mixed solution in a hydrothermal reaction kettle, carry out a constant-temperature reaction in an oven, and then naturally cool down;

[0009] Third step, take out the product from the hydrothermal reaction kettle, wash and filter it, and put the product in an oven to dry;

[0010] Fourth step, put the dried product into a muffle furnace for calcination, and cool down to obtain CoMo 1-y Cr y O4·(H2O) 0.75 Material.

[0011] Further, in the above technical solution, y = 0.01, 0.02, 0.03, 0.05.

[0012] Further, in the above technical solution, in the first step, the molar ratio of cobalt nitrate hexahydrate, ammonium molybdate tetrahydrate to ammonium fluoride is 1:1:3.

[0013] Further, in the above technical solution, in the second step, the molar ratio of ammonium molybdate tetrahydrate to potassium dichromate is 99:1, 98:2, 97:3, 95:5.

[0014] Further, in the above technical solution, in the second step, the constant-temperature reaction temperature is 140 °C and the constant-temperature reaction time is 8 hours.

[0015] Further, in the above technical solution, in the third step, the reaction product is washed and filtered with pure water. The reaction product is placed in pure water to form a suspension, and ultrasonic treatment is carried out in an ultrasonic cleaner for 3 minutes, and then the suspension is suction filtered, and the total washing is carried out 3 times.

[0016] Further, in the above technical solution, in the third step, the drying temperature is 80 °C and the drying time is 1 hour.

[0017] Further, in the above technical solution, in the fourth step, the calcination temperature is 250 °C, the constant-temperature calcination time is 3 hours, and the heating program is set to 2 hours, and the temperature is reduced to below 200 °C for 2 hours.

[0018] The present invention also provides the application of the foregoing molybdenum-site doped chromium element CoMo 1-y Cr y O4·(H2O) 0.75 material in a supercapacitor.

[0019] Advantages of the invention:

[0020] The invention provides a molybdenum-site doped chromium element CoMo 1-y Cr y O4·(H2O) 0.75 material. The material coexists in a rod-like structure and a split-cell-like structure. Its synthesis method is simple and easy to operate, and the raw materials used are cheap and easily available. After doping with chromium element, the electrochemical performance of the material can be well improved, and a split-cell morphology can also be observed in the microscopic morphology. This morphology is covered with wrinkles, which can well increase the specific surface area of the material, and thus increase the contact area with the electrolyte. The preparation process is also relatively environmentally friendly and does not pollute the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 XRD pattern of the molybdenum-site doped chromium element CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material in Example 3 of the present invention;

[0022] Figure 2 XPS pattern of the molybdenum-site doped chromium element CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material in Example 3 of the present invention;

[0023] Figure 3 SEM image of the molybdenum-site doped chromium element CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material in Example 3 of the present invention;

[0024] Figure 4 For CoMo with chromium element doped at the molybdenum site in Example 3 of the present invention 0.97 Cr 0.03 O4·(H2O) 0.75 GCD diagram of the material at a current density of 0.001 A / cm2;

[0025] Figure 5 For CoMo with chromium element doped at the molybdenum site in Example 3 of the present invention 0.97 Cr 0.03 O4·(H2O) 0.75 EDS diagram of the material; where: a is the EDS spectrum of the rod-like structure, b is the EDS spectrum of the split cell-like structure;

[0026] Figure 6 For CoMo with chromium element doped at the molybdenum site in Example 3 of the present invention 0.97 Cr 0.03 O4·(H2O) 0.75 Element distribution diagram of the material; where: a is the Co element distribution diagram, b is the Mo element distribution diagram, c is the O element distribution diagram;

[0027] Figure 7 For CoMo with chromium element doped at the molybdenum site in Example 3 of the present invention 0.97 Cr 0.03 O4·(H2O) 0.75 Infrared spectrum diagram of the material;

[0028] Figure 8 For CoMo with chromium element doped at the molybdenum site in Example 3 of the present invention 0.97 Cr 0.03 O4·(H2O) 0.75 Raman spectrum diagram of the material;

[0029] Figure 9 For CoMo with chromium element doped at the molybdenum site in Example 5 of the present invention 1-y Cr y O4·(H2O) 0.75 Specific capacity diagram of the material. Detailed implementation manners

[0030] The present invention is further described below through specific examples. However, these examples are merely exemplary and are not limited to the protection scope of the present invention being only the embodiments. In the following embodiments, the reagents, materials, and instruments used, if not otherwise specified, are all conventional reagents, conventional materials, and conventional instruments, which can be commercially obtained, and the reagents involved can also be obtained by conventional synthesis methods.

[0031] Example 1

[0032] First step: Weigh 1.16 g of cobalt nitrate hexahydrate, disperse it in deionized water and stir. Then, successively add 4.8940 g of ammonium molybdate tetrahydrate and 0.444 g of ammonium fluoride, and stir.

[0033] Second step: Add 0.0118 g of potassium dichromate to the uniformly mixed solution and stir for 2 hours; the molar ratio of potassium dichromate to ammonium molybdate tetrahydrate is 1:99.

[0034] Third step: Continuously stir the above mixed solution for 2 h, then put it into a hydrothermal reaction kettle, keep it at a constant temperature of 140 °C in an oven for 8 hours, and then cool down naturally.

[0035] Fourth step: Take out the reaction product from the hydrothermal reaction kettle, carry out the cleaning operation, wash and filter the reaction product with pure water, place the reaction product in pure water to form a suspension, and perform ultrasonic treatment for 3 minutes in an ultrasonic cleaner, then carry out suction filtration on the suspension, and wash a total of 3 times.

[0036] Fifth step: Put the washed and filtered product into an oven and dry it at 80 °C for 1 hour.

[0037] Sixth step: Calcine the dried product in a muffle furnace. After the calcination is completed, cool it down with the furnace to obtain CoMo 0.99 Cr 0.01 O4·(H2O) 0.75 material. The calcination temperature is 250 °C, where the heating program is set for 2 hours, the temperature is reduced to below 200 °C for 2 hours, and the constant-temperature calcination time is 3 hours.

[0038] Example 2

[0039] First step: Weigh 1.16 g of cobalt nitrate hexahydrate, disperse it in deionized water and stir. Then, successively add 4.8446 g of ammonium molybdate tetrahydrate and 0.444 g of ammonium fluoride, and stir.

[0040] Second step: Add 0.0236 g of potassium dichromate to the uniformly mixed solution and stir for 2 hours; the molar ratio of potassium dichromate to ammonium molybdate tetrahydrate is 2:98.

[0041] Third step: Continuously stir the above mixed solution for 2 h, then put it into a hydrothermal reaction kettle, keep it at a constant temperature of 140 °C in an oven for 8 hours, and then cool down naturally.

[0042] Fourth step: Take out the reaction product from the hydrothermal reaction kettle, carry out the cleaning operation, wash and filter the reaction product with pure water, place the reaction product in pure water to form a suspension, and perform ultrasonic treatment for 3 minutes in an ultrasonic cleaner, then carry out suction filtration on the suspension, and wash a total of 3 times.

[0043] Step 5: Put the washed filtered product into an oven and dry it at 80 °C for 1 hour.

[0044] Step 6: Place the dried product in a muffle furnace for calcination. After the calcination is completed, cool it down with the furnace to obtain CoMo 0.98 Cr 0.02 O4·(H2O) 0.75 material. The calcination temperature is 250 °C, where the heating program is set for 2 hours, cooled down to below 200 °C for 2 hours, and the constant-temperature calcination time is 3 hours.

[0045] Example 3

[0046] Step 1: Weigh 1.16 g of cobalt nitrate hexahydrate, disperse it in deionized water and stir, then successively add 4.7952 g of ammonium molybdate tetrahydrate and 0.444 g of ammonium fluoride, and stir.

[0047] Step 2: Add 0.0354 g of potassium dichromate to the uniformly mixed solution and stir for 2 hours; the molar ratio of potassium dichromate to ammonium molybdate tetrahydrate is 3:97;

[0048] Step 3: Continuously stir the above mixed solution for 2 h, then put it into a hydrothermal reaction kettle, keep it at a constant temperature of 140 °C in an oven for 8 hours, and then cool it down naturally.

[0049] Step 4: Take out the reaction product from the hydrothermal reaction kettle, carry out a cleaning operation, wash and filter the reaction product with pure water, place the reaction product in pure water to form a suspension, and carry out ultrasonic treatment in an ultrasonic cleaner for 3 minutes, then carry out suction filtration on the suspension, and wash a total of 3 times.

[0050] Step 5: Put the washed filtered product into an oven and dry it at 80 °C for 1 hour.

[0051] Step 6: Place the dried product in a muffle furnace for calcination. After the calcination is completed, cool it down with the furnace to obtain CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material. The calcination temperature is 250 °C, where the heating program is set for 2 hours, cooled down to below 200 °C for 2 hours, and the constant-temperature calcination time is 3 hours.

[0052] It can be seen from Figure 1 that the XRD pattern of the CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material synthesized by the hydrothermal method, compared with CoMoO4·(H2O) 0.75The card (JCPDS 97-015-3169) corresponds well. The main diffraction peaks at 9.8°, 13.5°, 29.5° and 32.9° were observed in the XRD pattern. These characteristic peaks correspond to the (001), (100), (201) and (201) crystal planes of the CoMoO4·(H2O) 0.75 phase. The positions of these diffraction peaks indicate that the crystal structure of the material is consistent with the standard sample, verifying the successful synthesis of CoMoO4·(H2O) 0.75 material by the hydrothermal method. In addition, the peak position shift is within 0.5°, showing a slight effect of Cr doping on the lattice structure, and this slight shift is also within the reasonable error range, indicating that doping does not significantly change the crystal structure of the material. In addition, except for the CoMoO4·(H2O) 0.75 diffraction peaks, no other miscellaneous peaks were observed, which further verified the high purity of the prepared sample. Through comprehensive analysis, it can be seen that the doping element Cr has been successfully introduced into the CoMoO4·(H2O) 0.75 lattice without introducing other impurity phases, meaning that doping with Cr elements may affect the properties of the material through minor lattice distortions or local strains without changing its overall crystal phase structure.

[0053] Figure 2 is CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 For the XPS full spectrum of the material, the characteristic peaks of cobalt, molybdenum and oxygen elements can be clearly observed. Fitting this energy spectrum, the characteristic peak at 796.59 eV represents the Co2p 1 / 2 peak, and the characteristic peak at 780.68 eV is the Co2p 3 / 2 characteristic peak, and two relatively strong satellite peaks accompany the main peak at the same time, which constitute the Co 2+ typical characteristic peaks. The peak of the Co2p 3 / 2 orbital shifts from 781.3 eV to 780.68 eV relative to the pure phase material, indicating that the XPS peak of the Co 2+ ion shifts due to the addition of Cr ions, indicating that the addition of Cr ions affects the Co 2+ chemical environment, but the degree of shift is relatively small. The binding energy at 234.71 eV represents the Mo3d 3 / 2 orbital, and the binding energy at 231.58 eV represents the Mo3d 5 / 2 orbital. From this, it can be judged that the valence state of the Mo element is +6, showing that the doping of Cr elements at the molybdenum site and the chemical state of Mo remains stable.

[0054] Figure 3 is CoMo 0.97 Cr 0.03 O4·(H2O) 0.75SEM images of the material, doped and modified with Cr element, show that the main morphology of the material in the microstructure is rod-shaped, as Figure 3 (a) shows. This consistency indicates that the doping element does not significantly change the basic morphology of the material, but may affect its electrochemical performance by changing the surface characteristics of the material. The surface of the rod-shaped structure is covered with wrinkles, which is very beneficial for supercapacitor materials. The wrinkled surface provides a larger specific surface area, creating more active sites for the adsorption of the electrolyte. This geometric feature enables the material particles to be fully wetted, ensuring the uniform distribution of the electrolyte on the surface and in the pores of the material. Good electrolyte contact can improve the ion transport efficiency, thereby enhancing the electrochemical activity and capacity of the electrode material. In addition, split cell-like particles were also observed, as Figure 3 (b) shows. Some of these particles show obvious lobed splitting, and this morphology further enhances the ability of the material to store the electrolyte, because the splitting morphology in the structure provides more storage space for the electrolyte and may also extend the discharge time of the material by increasing the infiltration depth of the electrolyte. By comparison, it can be seen that the doping of chromium element has a certain influence on the surface characteristics and particle morphology of the material.

[0055] In Figure 4 For CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 The galvanostatic charge-discharge graph of the material shows that the extension of the charge-discharge time is usually associated with the high specific capacity and excellent cycle stability of the material, which indicates that CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 The material has better charge storage and release capabilities, so its electrochemical performance is relatively good. Through calculation, it can be known that at a current density of 0.001 A / cm 2 , the capacity of the doped CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 The material can reach up to 19.86 F / cm 2 , which is much higher than the materials prepared by doping other elements.

[0056] Figure 5 For CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 The element distribution map of the material, Figure 5 (a) is the EDS map of the rod-shaped structure. It can be seen from this map that the distributions of Co, Mo and O elements are very uniform. This element distribution uniformity ensures the uniformity and stability of charge transport during the charge-discharge process of the material, thereby improving the overall performance of the material. However, in the split cell-like structure morphology, the element distributions show different characteristics. FromFigure 5 (b) It can be seen from the EDS diagram that this morphology is mainly composed of Mo oxides, while the cobalt content is relatively low. This indicates that in a specific morphology, the Mo element may play a more dominant role in the structure formation, while the Co element participates less. This non-uniform element distribution may be due to different crystal growth kinetics or heat treatment conditions. The dominant position of Mo oxides in the cellular structure may affect the local electrochemical properties of the material. The high Mo content may endow this region with different charge storage capabilities and reaction paths, thus affecting the overall material properties. Although the Co element content is low in this morphology, its uniform distribution in other regions still plays an important role in the overall conductivity and stability of the material.

[0057] Figure 6 It is CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 For the element distribution diagram of the material, it can be seen that the distributions of Co, Mo, and O elements are very uniform.

[0058] Figure 7 It is CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 For the infrared spectrum of the material, the characteristic absorption peaks shown in the infrared spectrum are mainly composed of Mo-O bonds and Co-O bonds. Below 1000 cm -1 The spectral bands are mainly attributed to the stretching vibrations of metal-oxygen. These vibration modes are characteristic manifestations of metal-oxygen bonds in the material structure. Especially at 840 cm -1 the absorption peak at this position marks the stretching vibration of the Co-O bond, while the strong absorption peaks at 950 cm -1 and 430 cm -1 represent the characteristic peaks of the Mo-O bond. The existence of these characteristic peaks indicates that despite the Cr doping, the basic structural framework of the material is still dominated by Co-O and Mo-O bonds.

[0059] Figure 8 It shows the Raman spectrum of CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 For the Raman spectrum of the material, it provides more information about molecular vibrations. In the Raman spectrum, the peak located at 332 cm -1 corresponds to the Co-O-Mo vibration mode, while the peak near 810 cm -1 is related to the vibration of the O-Mo-O bond. The peak at 931 cm -1 has the largest intensity, reflecting the vibration mode of the Mo-O bond. The identification of these vibration modes further confirms the existence of Co and Mo oxides. CoMo 0.97 Cr 0.03 O4·(H2O) 0.75The peak position of the Raman spectrum of the material shows a slight shift, which may be caused by the doping element Cr. Different types of doping ions may change the local electronic environment and intermolecular interactions of the material, thus affecting the peak intensity and peak position. Although such subtle changes do not significantly alter the macroscopic structure of the material.

[0060] Example 4

[0061] First step, weigh 1.16 g of cobalt nitrate hexahydrate, disperse it in deionized water and stir, then successively add 4.6963 g of ammonium molybdate tetrahydrate and 0.444 g of ammonium fluoride, and stir.

[0062] Second step, add 0.059 g of potassium dichromate to the uniformly mixed solution and stir for 2 hours; the molar ratio of potassium dichromate to ammonium molybdate tetrahydrate is 5:95;

[0063] Third step, continuously stir the above mixed solution for 2 h, then put it into a hydrothermal reaction kettle, keep it at a constant temperature of 140 °C in an oven for 8 hours, and then cool it naturally.

[0064] Fourth step, take out the reaction product from the hydrothermal reaction kettle, carry out cleaning operations, wash and filter the reaction product with pure water, place the reaction product in pure water to form a suspension, and perform ultrasonic treatment in an ultrasonic cleaner for 3 minutes, then carry out suction filtration on the suspension, and wash a total of 3 times.

[0065] Fifth step, put the washed and filtered product into an oven and dry it at 80 °C for 1 hour.

[0066] Sixth step, calcine the dried product in a muffle furnace. After the calcination is completed, cool it with the furnace to obtain CoMo 0.95 Cr 0.05 O4·(H2O) 0.75 material. The calcination temperature is 250 °C, where the heating program is set for 2 hours, the temperature is reduced to below 200 °C for 2 hours, and the constant-temperature calcination time is 3 hours.

[0067] Example 5

[0068] Prepare the CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material into a supercapacitor working electrode in-situ grown on nickel foam.

[0069] First step, weigh 1.16 g of cobalt nitrate hexahydrate, disperse it in deionized water and stir, then successively add 4.7952 g of ammonium molybdate tetrahydrate and 0.444 g of ammonium fluoride, and stir.

[0070] Step 2: Add 0.0354 g of potassium dichromate to the uniformly mixed solution and stir for 2 hours. The molar ratio of potassium dichromate to ammonium molybdate tetrahydrate is 3:97.

[0071] Step 3: After continuously stirring the above mixed solution for 2 h, add nickel foam with a size of 1 cm × 1 cm × 1.5 mm. Subsequently, the mixed solution and the nickel foam are placed together in a hydrothermal reaction kettle and reacted at a constant temperature of 140 °C in an oven for 8 hours, and then naturally cooled.

[0072] Step 4: Take out the nickel foam from the hydrothermal reaction kettle and perform a cleaning operation. Wash and filter the nickel foam with pure water. Place the reaction product in pure water to form a suspension and perform ultrasonic treatment in an ultrasonic cleaner for 3 minutes, with a total of 3 washes.

[0073] Step 5: Put the washed nickel foam into an oven and dry it at 80 °C for 1 hour.

[0074] Step 6: Place the dried nickel foam in a muffle furnace for calcination. After the calcination is completed, cool it with the furnace to obtain nickel foam grown with CoMo 0.97 Cr 0.03 O4·(H2O) 0.75 material. The calcination temperature is 250 °C, where the heating program is set for 2 hours, cooled to below 200 °C for 2 hours, and the constant-temperature calcination time is 3 hours.

[0075] Step 7: The platinum electrode is selected as the counter electrode, mainly because of its excellent electrical conductivity and stable electrochemical performance. The mercury oxide electrode is used as the reference electrode to provide a stable potential reference, and 3 mol / L KOH solution is used as the electrolyte.

[0076] Figure 9 For the constant current charge-discharge diagram of CoMo 1-y Cr y O4·(H2O) 0.75 material in-situ grown on nickel foam, at a current density of 0.001 A / cm 2 the capacity of the material prepared by doping 3% Cr element can reach up to 19.86 F / cm 2 , which is much higher than the materials prepared by doping other elements. And after doping with Cr element modification, the electrochemical properties of the four materials prepared are significantly better than those of the materials modified by doping other elements.

[0077] According to the description of the above specification, those skilled in the art to which the present invention pertains can also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. Cobalt molybdenum doped with chromium element 1-y Cr y O4·(H2O) 0.75 The material is characterized in that: The material coexists in a rod-like structure and a split-cell-like structure, with 2θ values of 9.8°, 13.5°, 29.5°, and 32.9° in XRD; the XPS peaks appear at 796.59 eV, 780.68 eV, 234.71 eV, and 231.58 eV; the valence state of the Mo element is +6; y = 0.01, 0.02, 0.03, 0.

05.

2. The CoMo with chromium element doped at molybdenum position as described in claim 1 1-y Cr y O4·(H2O) 0.75 The preparation method of the material is characterized in that It includes the following steps: In the first step, cobalt nitrate hexahydrate is dispersed in deionized water, and ammonium molybdate tetrahydrate and ammonium fluoride are added in sequence and stirred evenly. In the second step, potassium dichromate is added and stirred evenly. The mixed solution is placed in a hydrothermal reactor and reacted at a constant temperature in an oven, and then cooled naturally. In the third step, the product in the hydrothermal reactor is washed and filtered, and the product is placed in an oven for drying. Step 4: Calcinate the dried product in a muffle furnace and cool down to obtain CoMo 1-y Cr y O4·(H2O) 0.75 material.

3. The preparation method of the material according to claim 2, characterized in that: In the first step, the molar ratio of cobalt nitrate hexahydrate, ammonium molybdate tetrahydrate to ammonium fluoride is 1:1:

3.

4. The preparation method of the material according to claim 2, characterized in that: In the second step, the molar ratio of ammonium molybdate tetrahydrate to potassium dichromate is 99:1, 98:2, 97:3, 95:

5.

5. The preparation method of the material according to claim 2, characterized in that: In the second step, the constant temperature reaction temperature is 140 °C and the constant temperature reaction time is 8 hours.

6. The preparation method of the material according to claim 2, characterized in that: In the third step, the reaction product is washed and filtered with pure water. The reaction product is placed in pure water to form a suspension, and ultrasonic treatment is carried out in an ultrasonic cleaner for 3 minutes, and then the suspension is suction filtered, and the total washing is carried out 3 times.

7. The preparation method of the material according to claim 1, characterized in that: In the third step, the drying temperature is 80 °C and the drying time is 1 hour.

8. The preparation method of the material according to claim 1, characterized in that: In the fourth step, the calcination temperature is 250 °C and the constant temperature calcination time is 3 hours, where the heating program is set for 2 hours and the temperature is lowered to below 200 °C for 2 hours.

9. The application of the molybdenum-site doped chromium element CoMo 1-y Cr y O4 . (H2O) 0.75 material in supercapacitors.

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