An ultrathin trimanganese tetraoxide nanobelt, a preparation method and application thereof

Abstract

The application belongs to the technical field of trimanganese tetroxide material, and specifically discloses an ultrathin trimanganese tetroxide nanobelt which is a nanobelt with a network structure. The ultrathin trimanganese tetroxide nanobelt can efficiently and long-time catalyze and degrade volatile organic compounds at room temperature and low temperature, and has important significance for the wide application of the Mn3O4 nanomaterial. Moreover, the preparation method of the catalytic material is simple, low in cost and long in service life.

Description

Technical Field

[0001] This invention belongs to the technical field of manganese tetroxide materials, specifically relating to an ultrathin manganese tetroxide nanoribbon, particularly to a method for preparing the ultrathin manganese tetroxide nanoribbon, and further relating to the application of the ultrathin manganese tetroxide nanoribbon. Background Technology

[0002] Manganese tetroxide (Mn3O4) has a spinel structure, formed by a combination of tetrahedral and octahedral configurations, in which Mn 2 + Occupying a tetrahedron, Mn 3+ Occupying an octahedral structure, oxygen atoms are densely packed in a tetragonal or cubic arrangement. Compared to MnO2, Mn3O4 exhibits higher thermal stability, moisture resistance, and reactivity, and is frequently used in research across multiple fields such as catalysis, energy storage, energy conversion, and gas sensing. Therefore, applying Mn3O4 to the catalytic decomposition of volatile organic compounds (VOCs) is a promising option. In 2010, Kim et al. from South Korea (Appl. Catal. B, 2010, 98:180-185) studied the catalytic degradation performance of commercial manganese oxides on benzene and toluene, finding that the catalytic activity of commercial Mn3O4 was significantly superior to that of commercial Mn2O3 and MnO2. Russo et al. from the Polytechnic University of Turin (Appl. Catal. B, 2015, 163: 277-287) prepared mesoporous Mn2O3, Mn3O4, and MnxOy (a mixture of Mn2O3 and MnO2) catalysts and tested their catalytic activity against various VOCs (ethylene, propylene, toluene, and their mixtures). The results showed that Mn3O4 exhibited the best catalytic performance for the oxidative decomposition of toluene, achieving a conversion rate of 90% at 248℃. This can be attributed to the abundant oxygen vacancies and surface active oxygen in Mn3O4. Wang Shuang's research group at Taiyuan University of Technology (Chem. Eng. Sci., 2022, 263: 118065) ​​used Mn-MOF with different ligands as precursors. The Mn3O4 catalyst prepared by heat treatment showed excellent performance for the catalytic oxidation of toluene, achieving a toluene conversion rate of 90% at 218℃ (toluene concentration = 1000 ppm, space velocity = 20 Lg). -1 h -1 This catalyst exhibits good stability, recyclability, and moisture resistance. However, most studies on its relatively stable catalytic activity under humid conditions have achieved this at higher reaction temperatures, and the catalysts still slowly deactivate during long-term testing. Furthermore, the catalysts achieve 100% conversion temperatures (above 240°C) for high concentrations of VOCs (1000 ppm), while studies on the decomposition of low concentrations of VOCs (50-1000 ppb) are limited, neglecting the impact of catalyst adsorption of low-concentration pollutants on the reaction.

[0003] Therefore, it is necessary to conduct in-depth research on VOCs catalysts in order to improve the catalytic activity of catalysts at lower reaction temperatures and make them suitable for the decomposition of low concentrations of VOCs. Summary of the Invention

[0004] This invention is based on the inventors' discoveries and understanding of the following facts and problems: the crystal structure and morphology of a catalyst have a significant impact on its catalytic activity. The content and type of surface defects in a catalyst largely depend on its microstructure; materials with smaller particle sizes and higher surface exposure are more conducive to the exposure of active sites, and some catalysts with special morphologies are also more likely to expose active crystal faces. In related technologies, the morphology of Mn3O4 is mainly nanowires, nanosheets, and nanospheres, but these morphologies of Mn3O4 still have insufficient performance and the problem of high catalytic reaction temperature for VOCs decomposition.

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose an ultrathin manganese tetroxide nanoribbon that can efficiently and for extended periods catalyze the degradation of volatile organic compounds at room temperature and low temperatures. This is of great significance for the widespread application of Mn3O4 nanomaterials. Furthermore, the preparation method of this catalytic material is simple, low-cost, and has a long service life.

[0006] The ultrathin manganese tetroxide nanoribbons of this invention are manganese tetroxide nanoribbons with a network structure.

[0007] The advantages and technical effects of the ultrathin manganese tetroxide nanoribbons in this invention are as follows: the manganese tetroxide in this invention has the morphology of nanoribbons and self-assembles to form a network structure. This morphology provides excellent catalytic performance for manganese tetroxide, enabling efficient and long-term catalytic degradation of volatile organic compounds at room temperature and low temperature. In addition, this material has the advantages of low cost and long service life.

[0008] In some embodiments, the aspect ratio of the manganese tetroxide nanoribbons is 30-600, preferably 100-600, and more preferably 200-600.

[0009] In some embodiments, the thickness of the manganese tetroxide nanoribbons is 1-5 nm.

[0010] This invention also provides a method for preparing ultrathin manganese tetroxide nanoribbons, comprising the following steps:

[0011] a. Add potassium permanganate to deionized water and stir to dissolve it, thus obtaining a potassium permanganate solution;

[0012] b. Mix oleylamine, ethylene glycol and deionized water to form an emulsion;

[0013] c. Add the potassium permanganate solution obtained in step a to the emulsion in step b, heat in a water bath, and react, wherein the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is not less than 1.5:1;

[0014] d. Add an aqueous solution of H2SO4 to the reaction solution from step c, and continue the reaction. The concentration of H2SO4 in 1 ml of the aqueous solution is [missing value]. + The volume ratio of the H2SO4 aqueous solution to the reaction solution obtained in step c is 1:80-120, not exceeding 10 mmol.

[0015] e. The product obtained in step d is centrifuged, washed, and dried to obtain ultrathin manganese tetroxide nanoribbons.

[0016] The advantages and technical effects of the preparation method of ultrathin manganese tetroxide nanoribbons in this invention are as follows: 1. In the method of this invention, by adding oleylamine as a structure directing agent and dispersant, manganese tetroxide can form an ultrathin structure, thereby improving the catalytic activity of manganese tetroxide; 2. In the method of this invention, ethylene glycol is added as a reducing agent to react with potassium permanganate to obtain manganese tetroxide; 3. In the method of this invention, after the reaction of diethanol with potassium permanganate has proceeded for a period of time, sulfuric acid is added, which can promote the vigorous reaction and directional adhesion growth, thereby promoting the formation of nanoribbons; 4. In this invention... In this method, by strictly controlling the amounts of ethylene glycol and sulfuric acid, manganese tetroxide forms ultrathin nanoribbons and self-assembles into a network structure. If the amount of ethylene glycol is too small, the reaction will be incomplete, resulting in the inability to form an ultrathin nanoribbon structure. If the amount of sulfuric acid is too large, the crystals will be excessively corroded, which will also result in the inability to form an ultrathin nanoribbon structure. 5. In the method of this embodiment, a water bath method is used for synthesis, which is simple, low-cost, and easy to promote and apply. 6. The ultrathin manganese tetroxide nanoribbons prepared by the method of this embodiment can efficiently and for a long time catalytically degrade volatile organic compounds at room temperature and low temperature.

[0017] In some embodiments, in step a, the concentration of potassium permanganate is 0.01-0.07 mol / L; in step b, the volume ratio of oleylamine, ethylene glycol, and deionized water is (0.01-0.06):(0.01-0.05):1; and in step c, the volume ratio of the potassium permanganate solution to the emulsion is (5-7):(3-5).

[0018] In some embodiments, in step c, the molar ratio of ethylene glycol to potassium permanganate is (2-25):1.

[0019] In some embodiments, in step c, the reaction temperature is 50-90°C and the reaction time is 1-4 hours.

[0020] In some embodiments, in step d, after adding the H2SO4 aqueous solution, the reaction time is 1-8 hours.

[0021] In some embodiments, in step e, the washing process involves sequentially washing with cyclohexane, ethanol, and deionized water 1-5 times.

[0022] This invention also provides an application of ultrathin manganese tetroxide nanoribbons in the degradation of volatile organic compounds. Attached Figure Description

[0023] Figure 1 These are scanning electron microscope (SEM) images of the ultrathin manganese tetroxide nanoribbons prepared in Example 1; where a is low magnification and b is high magnification.

[0024] Figure 2 These are scanning electron microscope (SEM) images of the ultrathin manganese tetroxide nanoribbons prepared in Example 2; where a is low magnification and b is high magnification.

[0025] Figure 3 These are atomic force microscopy images of the ultrathin manganese tetroxide nanoribbons prepared in Example 2;

[0026] Figure 4 This is the XRD pattern of the ultrathin manganese tetroxide nanoribbons prepared in Example 2;

[0027] Figure 5 These are scanning electron microscope (SEM) images of the ultrathin manganese tetroxide nanoribbons prepared in Example 3; where a is low magnification and b is high magnification.

[0028] Figure 6 These are scanning electron microscope (SEM) images of the ultrathin manganese tetroxide nanoribbons prepared in Example 4; where a is low magnification and b is high magnification.

[0029] Figure 7 These are scanning electron microscope (SEM) images of manganese tetroxide prepared in Comparative Example 1; where a is low magnification and b is high magnification.

[0030] Figure 8 This is a comparison of electron paramagnetic resonance (EPR) images of the ultrathin manganese tetroxide nanoribbons prepared in Example 2 and the manganese tetroxide nanoparticles prepared in Comparative Example 1. a) hydroxyl radicals (·OH); b) superoxide radicals (·O). 2- );

[0031] Figure 9 These are scanning electron microscope (SEM) images of manganese tetroxide prepared in Comparative Example 2; where a is low magnification and b is high magnification.

[0032] Figure 10 This is a comparison chart showing the effects of manganese tetroxide prepared in Examples 1-4 and Comparative Example 1 on the catalytic degradation of toluene;

[0033] Figure 11 This is a comparison chart showing the effects of continuous use at room temperature of manganese tetroxide prepared in Example 2 and Comparative Example 1. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0035] The ultrathin manganese tetroxide nanoribbons of this invention are manganese tetroxide nanoribbons with a network structure.

[0036] The ultrathin manganese tetroxide nanoribbons of this invention have the morphology of manganese tetroxide as nanoribbons and they self-assemble to form a network structure. This morphology provides manganese tetroxide with excellent catalytic performance, enabling efficient and long-term catalytic degradation of volatile organic compounds at room temperature and low temperature. In addition, this material has the advantages of low cost and long service life.

[0037] In some embodiments, the aspect ratio of the manganese tetroxide nanoribbons is 30-600, preferably 100-600, and more preferably 200-600. In these embodiments, the preferred aspect ratio of the manganese tetroxide nanoribbons is beneficial for further improving the catalytic activity of manganese tetroxide, reducing the reaction temperature for degrading volatile organic compounds, and increasing the removal rate of volatile organic compounds.

[0038] In some embodiments, the thickness of the manganese tetroxide nanoribbons is 1-5 nm, preferably 1-4 nm, and more preferably 1-3 nm. In this embodiment of the invention, the preferred thickness of the manganese tetroxide nanoribbons results in an ultrathin nanoribbon structure, which is beneficial for improving the catalytic activity of manganese tetroxide and can achieve a 100% removal rate of volatile organic compounds at room temperature.

[0039] This invention also provides a method for preparing ultrathin manganese tetroxide nanoribbons, comprising the following steps:

[0040] a. Add potassium permanganate to deionized water and stir to dissolve it, thus obtaining a potassium permanganate solution;

[0041] b. Mix oleylamine, ethylene glycol and deionized water to form an emulsion;

[0042] c. Add the potassium permanganate solution obtained in step a to the emulsion in step b, heat in a water bath, and react. The molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is not less than 1.5:1, preferably (2-25):1, more preferably (4-10):1, and even more preferably (5-8):1.

[0043] d. Add an aqueous solution of H2SO4 to the reaction solution from step c, and continue the reaction. The concentration of H2SO4 in 1 ml of the aqueous solution is [missing value]. + The volume ratio of the H2SO4 aqueous solution to the reaction solution obtained in step c is 1:80-120, not exceeding 10 mmol, preferably 2-10 mmol.

[0044] e. The product obtained in step d is centrifuged, washed, and dried to obtain ultrathin manganese tetroxide nanoribbons.

[0045] The method for preparing ultrathin manganese tetroxide nanoribbons in this embodiment of the invention involves adding oleylamine as a structure directing agent and dispersant, enabling manganese tetroxide to form an ultrathin structure and improving its catalytic activity. In this embodiment, ethylene glycol is added as a reducing agent to react with potassium permanganate to obtain manganese tetroxide. In this embodiment, sulfuric acid is added after the reaction of diethanol and potassium permanganate has proceeded for a period of time, promoting vigorous reaction and directional adhesion growth, thus promoting the formation of nanoribbons. In this embodiment, the amounts of ethylene glycol and sulfuric acid are strictly controlled to allow manganese tetroxide to form ultrathin nanoribbons and self-assemble into a network structure. Insufficient ethylene glycol will result in incomplete reaction, preventing the formation of ultrathin nanoribbon structures; excessive sulfuric acid will cause excessive corrosion of the crystals, also preventing the formation of ultrathin nanoribbon structures. This embodiment employs a water bath synthesis method, which is simple, low-cost, and easy to promote and apply. The ultrathin manganese tetroxide nanoribbons prepared by this method can efficiently and for extended periods catalyze the degradation of volatile organic compounds at room temperature and low temperature.

[0046] In some embodiments, in step a, the concentration of potassium permanganate is 0.01-0.07 mol / L; in step b, the volume ratio of oleylamine, ethylene glycol, and deionized water is (0.01-0.06):(0.01-0.05):1; and in step c, the volume ratio of the potassium permanganate solution to the emulsion is (5-7):(3-5).

[0047] In some embodiments, in step c, the reaction temperature is 50-90°C, and the reaction time is 1-4 hours. In this embodiment, the water bath reaction temperature and time are further preferred to control the aspect ratio of the nanoribbons within a suitable range. If the reaction temperature is too high, the thickness and width will increase, and the aspect ratio will decrease. If the reaction temperature is too low, the reaction will be incomplete, resulting in a shorter length and a smaller aspect ratio. If the reaction time is too long, the aspect ratio of the nanoribbons will be too small, which is not conducive to improving catalytic activity. If the reaction time is too short, the reaction time will be insufficient, resulting in too little manganese tetroxide generated, which cannot be directionally attached and grown to form nanoribbons.

[0048] In some embodiments, in step d, after adding the H2SO4 aqueous solution, the reaction time is 1-8 hours. In this embodiment of the invention, the reaction time after adding sulfuric acid is further controlled and preferred to ensure that the nanoribbons obtain a suitable aspect ratio. If the reaction time is too long, the thickness and width will increase, the aspect ratio will decrease, and the catalytic activity will deteriorate. If the reaction time is too short, the nanoribbons cannot be oriented and grow.

[0049] In some embodiments, in step e, the washing process involves sequentially washing with cyclohexane, ethanol, and deionized water 1-5 times.

[0050] This invention also provides an application of ultrathin manganese tetroxide nanoribbons in the degradation of volatile organic compounds. The ultrathin manganese tetroxide nanoribbons of this invention exhibit excellent catalytic activity, enabling efficient and prolonged catalytic degradation of volatile organic compounds at room temperature and low temperatures.

[0051] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0052] Example 1

[0053] a. Add potassium permanganate to 70 mL of deionized water and stir until completely dissolved to prepare a potassium permanganate solution with a concentration of 0.01 mol / L.

[0054] b. Mix oleylamine, ethylene glycol and deionized water in a volume ratio of 0.02:0.03:1 in an Erlenmeyer flask and sonicate for 10 min to form a 30 mL emulsion.

[0055] c. Then, the potassium permanganate solution is added directly to the continuously stirred emulsion, wherein the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 22:1. To prevent splashing, the Erlenmeyer flask is sealed and transferred to a 50°C water bath, and the mixture is stirred continuously for 2 hours.

[0056] d. Add 1 mL of H2SO4 aqueous solution to the reaction solution, wherein 1 mL of H2SO4 aqueous solution contains H + The concentration was 10 mmol, and the reaction continued for 4 hours.

[0057] e. The reaction product was centrifuged and washed twice with cyclohexane, ethanol and deionized water in sequence, and dried at 160℃ for 6 h to prepare ultrathin manganese tetroxide nanoribbons with a network structure.

[0058] The scanning electron microscope image of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is shown below. Figure 1 Figures a and 1b show that the aspect ratio of Mn3O4 nanoribbons is 30-100 and they have a network structure.

[0059] The thickness of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is 3.5-5 nm.

[0060] Example 2

[0061] a. Add potassium permanganate to 70 mL of deionized water and stir until completely dissolved to prepare a potassium permanganate solution with a concentration of 0.04 mol / L.

[0062] b. Mix oleylamine, ethylene glycol and deionized water in a volume ratio of 0.03:0.04:1 in an Erlenmeyer flask and sonicate for 10 min to form a 30 mL emulsion.

[0063] c. Then, potassium permanganate solution is added directly to the continuously stirred emulsion, wherein the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 7:1. The Erlenmeyer flask is sealed and transferred to an 80°C water bath, and the mixture is stirred continuously for 3 hours.

[0064] d. Add 1 mL of H2SO4 aqueous solution to the reaction solution, wherein 1 mL of H2SO4 aqueous solution contains H + 5 mmol H + Continue the reaction for 6 hours;

[0065] e. The reaction product was centrifuged and washed twice with cyclohexane, ethanol and deionized water in sequence, and dried at 105℃ for 16h to prepare ultrathin manganese tetroxide nanoribbons with a network structure.

[0066] The scanning electron microscope image of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is shown below. Figure 2 Figures a and 2b show that the aspect ratio of Mn3O4 nanoribbons is 200-600, and they have a network structure.

[0067] The atomic force microscope image of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is shown below. Figure 3 The thickness of the nanoribbons was observed to be approximately 1-1.5 nm, indicating that ultrathin Mn3O4 nanoribbons were successfully synthesized.

[0068] The XRD pattern of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is shown in the figure. Figure 4 ,pass Figure 4 It can be proven that the prepared material is manganese tetroxide crystal.

[0069] Example 3

[0070] a. Add potassium permanganate to 70 mL of deionized water and stir until completely dissolved to prepare a potassium permanganate solution with a concentration of 0.07 mol / L.

[0071] b. Mix oleylamine, ethylene glycol and deionized water in a volume ratio of 0.01:0.05:1 in an Erlenmeyer flask and sonicate for 10 min to form a 30 mL emulsion.

[0072] c. Then, potassium permanganate solution is added directly to the continuously stirred emulsion, wherein the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 5:1. The Erlenmeyer flask is sealed and transferred to a 70°C water bath, and the mixture is stirred continuously for 2 hours.

[0073] d. Add 1 mL of H2SO4 aqueous solution to the reaction solution, wherein 1 mL of H2SO4 aqueous solution contains H + The concentration was 2 mmol, and the reaction continued for 5 hours.

[0074] e. The reaction product was centrifuged and washed twice with cyclohexane, ethanol and deionized water in sequence, and dried at 60°C for 12 h to prepare ultrathin manganese tetroxide nanoribbons with a network structure.

[0075] The scanning electron microscope image of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is shown below. Figure 5 Figures a and 5b show that the aspect ratio of the Mn3O4 nanoribbons is 100-400, and they have a network structure.

[0076] The thickness of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is 3-4 nm.

[0077] Example 4

[0078] a. Add potassium permanganate to 70 mL of deionized water and stir until completely dissolved to prepare a potassium permanganate solution with a concentration of 0.06 mol / L.

[0079] b. Mix oleylamine, ethylene glycol and deionized water in a volume ratio of 0.04:0.05:1 in an Erlenmeyer flask and sonicate for 10 min to form a 30 mL emulsion.

[0080] c. Then, potassium permanganate solution is added directly to the continuously stirred emulsion, wherein the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 6:1. The Erlenmeyer flask is sealed and transferred to a 60°C water bath, and the mixture is stirred continuously for 3 hours.

[0081] d. Add 1 mL of H2SO4 aqueous solution to the reaction solution, wherein 1 mL of H2SO4 aqueous solution contains H + The concentration was 7 mmol, and the reaction continued for 3 hours.

[0082] e. The reaction product was centrifuged and washed twice with cyclohexane, ethanol and deionized water in sequence, and dried at 180℃ for 20h to prepare ultrathin manganese tetroxide nanoribbons with a network structure.

[0083] The scanning electron microscope image of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is shown below. Figure 6 Figures a and 6b show that the Mn3O4 nanoribbons have an aspect ratio of 300-500 and a network structure.

[0084] The thickness of the ultrathin manganese tetroxide nanoribbons prepared in this embodiment is 1.5-3 nm.

[0085] Example 5

[0086] The method is the same as in Example 2, except that in step c, the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 4:1.

[0087] Example 6

[0088] The method is the same as in Example 2, except that in step c, the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 8:1.

[0089] Example 7

[0090] The method is the same as in Example 2, except that in step c, the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 10:1.

[0091] Example 8

[0092] The method is the same as in Example 2, except that in step d, the H2SO4 in 1 mL of aqueous H2SO4 solution... + The value was 3 mmol.

[0093] Example 9

[0094] The method is the same as in Example 2, except that in step d, the H2SO4 in 1 mL of aqueous H2SO4 solution... + It was 8 mmol.

[0095] Example 10

[0096] The method is the same as in Example 2, except that in step d, the H2SO4 in 1 mL of aqueous H2SO4 solution... + The value is 10 mmol.

[0097] Example 11

[0098] The method is the same as in Example 2, except that in step c, the temperature of the water bath is 50°C.

[0099] Example 12

[0100] The method is the same as in Example 2, except that in step c, the temperature of the water bath is 60°C.

[0101] Example 13

[0102] The method is the same as in Example 2, except that in step c, the reaction time is 2 hours.

[0103] Example 14

[0104] The method is the same as in Example 2, except that in step c, the reaction time is 4 hours.

[0105] Example 15

[0106] The method is the same as in Example 2, except that in step d, the reaction time is 3 hours.

[0107] Example 16

[0108] The method is the same as in Example 2, except that in step d, the reaction time is 8 hours.

[0109] Comparative Example 1

[0110] The method is the same as in Example 2, except that in step c, the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 1:1.

[0111] The scanning electron microscope image of manganese tetroxide prepared in Comparative Example 1 is shown below. Figure 7 In samples a and 7b, the morphology of manganese tetroxide can be observed to be nanoparticles.

[0112] pass Figure 8 The electron paramagnetic resonance (EPR) comparison images show that the ultrathin manganese tetroxide nanoribbons prepared in Example 2 generate hydroxyl radicals (·OH) and superoxide radicals (·O). 2- The signal intensity was significantly stronger than that of the manganese tetroxide nanoparticles prepared in Comparative Example 1, indicating that the ultrathin manganese tetroxide nanoribbons have more oxygen vacancies and higher catalytic activity.

[0113] Comparative Example 2

[0114] The method is the same as in Example 2, except that in step d, the H2SO4 in 1 mL of aqueous H2SO4 solution... + The value was 12 mmol.

[0115] The scanning electron microscope image of manganese tetroxide prepared in Comparative Example 2 is shown below. Figure 9 In samples a and 9b, the morphology of manganese tetroxide can be observed to be nanoparticles.

[0116] Comparative Example 3

[0117] The method is the same as in Example 2, except that oleylamine is not added in step b.

[0118] Comparative Example 3 yielded manganese tetroxide nanoparticles.

[0119] Comparative Example 4

[0120] The method is the same as in Example 2, except that oleylamine is replaced with oleic acid in step b.

[0121] Comparative Example 4 yielded manganese tetroxide nanoparticles.

[0122] Comparative Example 5

[0123] The method is the same as in Example 2, except that step d is omitted.

[0124] Comparative Example 5 yielded manganese tetroxide nanoparticles.

[0125] Comparative Example 6

[0126] The method is the same as in Example 2, except that step d is omitted. In step c, after adding potassium permanganate solution to the emulsion, H2SO4 aqueous solution is added dropwise, and the reaction is carried out in a water bath at 60°C for 6 hours.

[0127] Comparative Example 6 yielded manganese tetroxide nanoparticles.

[0128] Performance testing:

[0129] 1. The manganese tetroxide products prepared in Examples 1-16 and Comparative Examples 1-6 were used in the catalytic degradation of toluene. The initial concentration of toluene gas was controlled at 10 ppm and the space velocity was 60 Lg. -1 h -1 The experimental results are shown in Table 1 and... Figure 10 .

[0130] Table 1

[0131]

[0132] As can be seen from Table 1, the catalytic degradation efficiency of toluene by the ultrathin manganese tetroxide nanoribbons prepared in the embodiments of the present invention is higher than that of the manganese tetroxide nanoparticles prepared in the comparative example. Furthermore, the ultrathin manganese tetroxide nanoribbons prepared in the embodiments of the present invention can achieve efficient degradation of toluene at a lower temperature. In particular, the ultrathin manganese tetroxide nanoribbons prepared in Example 2 can achieve a 100% removal rate of toluene at room temperature.

[0133] 2. The ultrathin manganese tetroxide nanoribbons prepared in Example 2 and the manganese tetroxide nanoparticles prepared in Comparative Example 1 were subjected to a comparative test of continuous use at room temperature.

[0134] Experimental conditions: initial toluene gas concentration 1 ppm, space velocity: 600 Lg -1 h -1The results are shown Figure 11 .

[0135] from Figure 11 It can be seen that the ultrathin manganese tetroxide nanoribbons prepared in Example 2 have a significantly higher adsorption capacity for low concentrations of toluene at room temperature than the manganese tetroxide nanoparticles prepared in Comparative Example 1, and also have a longer service life.

[0136] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0137] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. The application of ultrathin manganese tetroxide nanoribbons in the degradation of volatile organic compounds, characterized in that, The volatile organic compound is toluene, and the manganese tetroxide is a nanoribbon with a network structure. Its preparation method includes the following steps: a. Add potassium permanganate to deionized water and stir to dissolve it, thus obtaining a potassium permanganate solution; b. Mix oleylamine, ethylene glycol and deionized water to form an emulsion; c. Add the potassium permanganate solution obtained in step a to the emulsion in step b, heat in a water bath at 80-90°C, and react for 3-4 hours, wherein the molar ratio of ethylene glycol in the emulsion to potassium permanganate in the potassium permanganate solution is 7:

1. d. Add an aqueous solution of H2SO4 to the reaction solution from step c, and continue the reaction for 6-8 hours. The concentration of H2SO4 in 1 ml of the aqueous solution should be [missing information]. + The concentration is 5-8 mmol, and the volume ratio of the H2SO4 aqueous solution to the reaction solution obtained in step c is 1:80-120; e. The product obtained in step d is centrifuged, washed, and dried to obtain ultrathin manganese tetroxide nanoribbons.

2. The application of the ultrathin manganese tetroxide nanoribbons according to claim 1 in the degradation of volatile organic compounds, characterized in that, The aspect ratio of the manganese tetroxide nanoribbons is 100-600.

3. The application of the ultrathin manganese tetroxide nanoribbons according to claim 1 in the degradation of volatile organic compounds, characterized in that, The aspect ratio of the manganese tetroxide nanoribbons is 200-600.

4. The application of the ultrathin manganese tetroxide nanoribbons according to claim 1 or 2 in the degradation of volatile organic compounds, characterized in that, The thickness of the manganese tetroxide nanoribbons is 1-3.5 nm.

5. The application of the ultrathin manganese tetroxide nanoribbons according to claim 1 in the degradation of volatile organic compounds, characterized in that, In step a, the concentration of potassium permanganate is 0.01-0.07 mol / L; in step b, the volume ratio of oleylamine, ethylene glycol and deionized water is (0.01-0.06):(0.01-0.05):1; in step c, the volume ratio of potassium permanganate solution to emulsion is (5-7):(3-5).

6. The application of the ultrathin manganese tetroxide nanoribbons according to claim 1 in the degradation of volatile organic compounds, characterized in that, In step e, the washing process involves sequentially washing with cyclohexane, ethanol, and deionized water 1-5 times.

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