Mof-derived moo3 photocatalytic material and application thereof
By calcining and reducing Mo-MOF materials, MOF-derived MoO3 photocatalysts were prepared, which solved the problem of low CO2 reduction efficiency in the existing technology, achieved efficient CO2 reduction to CO, expanded the light absorption range and increased the reactive sites, and improved CO selectivity and yield.
Patent Information
- Application Number
- CN202311818645.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2043-12-27
AI Technical Summary
Existing semiconductor photocatalysts have low efficiency in reducing CO2 to CO, lack strong light absorption capacity, fast carrier separation efficiency, and abundant active sites.
MOF-derived MoO3 photocatalytic materials were prepared by calcining and reducing Mo-MOF materials. This process created oxygen vacancies, preserved the morphology and porous structure of the organic framework, extended the light absorption range to the near-infrared region, and increased the number of reactive sites.
The selectivity and efficiency of CO2 reduction to CO were improved, with CO production reaching 13.8766–32.67 μmol g⁻¹ h⁻¹, CH₄ production reaching 0.1445–0.5746 μmol g⁻¹ h⁻¹, and CO selectivity reaching 96.31–99.65%.
Smart Images
Figure CN117884112B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of CO2 catalytic reduction, and particularly relates to a MOF-derived MoO3 photocatalytic material and application. BACKGROUND
[0002] With the development of industry, the increasing consumption of fossil fuels not only depletes natural resources, but also leads to excessive emission of greenhouse gases, such as carbon dioxide (CO2), and energy and environment have become one of the biggest problems faced by mankind today. The traditional treatment method is time-consuming, energy-consuming and complex. Artificial photosynthesis is a promising strategy for solar-driven reduction of CO2 in the atmosphere to value-added chemicals / fuels (such as carbon monoxide (CO), methane (CH4), ethane (C2H6), etc.). The generated CO can be used as an important raw material gas for the Fischer-Tropsch synthesis reaction for the production of high-carbon chemicals.
[0003] At present, semiconductors are widely used in photocatalysts for photocatalytic reduction of CO2 to CO, including metal oxides, metal sulfides, metal carbides and heterostructures based on semiconductors. The photocatalytic CO2 reduction reaction of the semiconductor mainly consists of three steps: light absorption, separation and migration of photo-generated carriers and surface redox reaction. Although some progress has been made in this field, the photocatalytic activity of carbon dioxide reduction is still very low. Therefore, it is necessary to design a photocatalyst with strong light absorption capacity, fast carrier separation efficiency and rich active sites to improve the performance of CO2 reduction. SUMMARY
[0004] In view of the above shortcomings of the prior art, the application provides a MOF-derived MoO3 photocatalytic material and application.
[0005] To achieve the above object, the technical scheme adopted by the application is as follows:
[0006] A MOF-derived MoO3 photocatalytic material is obtained by sequentially calcining and reducing Mo-MOF materials to obtain a material containing oxygen vacancies.
[0007] The preparation method of the MOF-derived MoO3 photocatalytic material comprises the following steps:
[0008] (1) Molybdenum trioxide, organic framework and water are mixed for condensation reflux to obtain a Mo-MOF precursor; the Mo-MOF precursor is subjected to calcination treatment in a muffle furnace to obtain a MOF-derived MoO3 photocatalyst;
[0009] (2) The MOF-derived MoO3 photocatalyst, ascorbic acid and water are mixed and heated and stirred to obtain a MOF-derived MoO3 photocatalytic material.
[0010] In a preferred embodiment of the present application, the organic framework is imidazole, 2-methylimidazole or 2-ethylimidazole.
[0011] As a preferred embodiment of the present application, the molar ratio of the molybdenum trioxide to the organic framework is (0.5-1.2):(0.7-1.3).
[0012] As a preferred embodiment of the present application, the temperature of the condensation reflux is 80-120℃, and the time is 8-16h.
[0013] As a preferred embodiment of the present application, the temperature of the calcination treatment is 300-500℃, the time is 3-6h, the temperature rising speed is 1-5℃ / min, and the atmosphere is air.
[0014] As a preferred embodiment of the present application, the mass ratio of the MOF-derived MoO3 photocatalyst to ascorbic acid is 0.5-2.
[0015] As a preferred embodiment of the present application, the temperature of the heating stirring is 50-90℃, and the heating time is 0.2-6h.
[0016] As a preferred embodiment of the present application, the MOF-derived MoO3 photocatalytic material is orthorhombic crystal structure.
[0017] As a preferred embodiment of the present application, the MOF-derived MoO3 photocatalytic material has a diameter of 400nm-4μm, a pore size of 14-24nm, and a specific surface area of 10-31m 2 / g.
[0018] The present application also claims the MOF-derived MoO 3-x The application of the MOF-derived MoO
[0019] Compared with the prior art, the present application has the following beneficial effects:
[0020] (1) The Mo-MOF-derived MoO3 retains the morphology and porous structure of the Mo-MOF organic framework, which is conducive to the formation of oxygen vacancies during the reduction treatment, and provides more reaction active sites for the reduction of CO2. In addition, the Mo-MOF-derived MoO3 material is a semiconductor defect molybdenum oxide with a local surface plasmon resonance effect, which can expand the light absorption range to the near-infrared region, realize full-spectrum response, greatly strengthen the utilization of sunlight, and realize the photocatalytic reduction of CO2. Moreover, the formation of oxygen vacancies increases the adsorption energy of CO2 and reduces the adsorption energy of CO on the MOF-derived MoO3 photocatalytic material, and makes the intermediate (COOH*) of CO2 generating CO in the reaction process more stable, thereby improving the selectivity of CO generation during the reduction of CO2.
[0021] (2) The MOF-derived MoO3 photocatalytic material according to the present application has a CO production of 13.8766-32.67 μmol g -1 h -1 , a CH4 production of 0.1445-0.5746 μmol g -1 h -1 , and a CO selectivity of 96.31-99.65%. BRIEF DESCRIPTION OF DRAWINGS
[0022] Figure 1 The X-ray diffraction pattern of the MOF-derived MoO 3-x photocatalytic material or the MOF-derived MoO3 photocatalytic material.
[0023] Figure 2 The SEM image of the MOF-derived MoO3 photocatalytic material obtained in Example 3.
[0024] Figure 3 The specific surface area graph of the MOF-derived MoO3 photocatalytic material obtained in Example 1.
[0025] Figure 4 The UV-Vis-IR absorption spectrum of the MOF-derived MoO3 photocatalytic material obtained in Examples 1-3 and the MOF-derived MoO3 photocatalytic material prepared in Comparative Example 1.
[0026] Figure 5 The effect graph of the photocatalytic reduction of CO2 of the MOF-derived MoO3 photocatalytic material obtained in Example 1.
[0027] In the graph, MOF MoO3 is the MOF-derived MoO3 photocatalytic material prepared in Comparative Example 1, MOF MoO32.5h is the MOF-derived MoO3 photocatalytic material prepared in Example 1, MOF MoO31.5h is the MOF-derived MoO3 photocatalytic material prepared in Example 2, and MOF MoO30.5h is the MOF-derived MoO3 photocatalytic material prepared in Example 3. DETAILED DESCRIPTION
[0028] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples.
[0029] Example 1
[0030] A preparation method of a MOF-derived MoO3 photocatalytic material, comprising the following steps:
[0031] (1) 2 mol of MoO3 and 2 mol of imidazole were weighed and dissolved in 200 mL of deionized water, and ultrasonic treatment was performed for 10 min. Then, the solution was transferred into a 250 mL three-necked flask, and heated at 100°C for 12 h. After cooling to room temperature, a white sample was taken out, washed with deionized water by centrifugation for 3 times, washed with ethanol by centrifugation for 2 times, dried at 70°C, and finally ground in an agate mortar for 3 min to obtain a Mo-MOF precursor sample powder.
[0032] (2) The Mo-MOF precursor prepared in step (1) above was placed on a crucible cover and placed in a muffle furnace, and heated at a rate of 3°C / min at 450°C for 4 h. After cooling to room temperature, a sky blue sample was taken out, and ground in an agate mortar for 10 min to obtain a MOF-derived MoO3 photocatalytic material.
[0033] (3) The MOF-derived MoO3 photocatalytic material prepared in step (2) above was mixed with ascorbic acid and deionized water, and the mass ratio of the MOF-derived MoO3 photocatalytic material to ascorbic acid was 1:1.2, and 15 mL of deionized water was added. The mixture was placed on a heating table and stirred at 70°C for 2.5 h, and a dark blue sample was taken out. The sample was washed with deionized water by centrifugation for 3 times, washed with ethanol by centrifugation for 2 times, dried at 70°C, and finally ground in an agate mortar for 10 min to obtain a MOF-derived MoO3 photocatalytic material, which was denoted as MOF MoO32.5h.
[0034] Example 2
[0035] The only difference between the preparation method of the MOF-derived MoO3 photocatalytic material described in this example and that of Example 1 is that in step (3), the mass ratio of the MOF-derived MoO3 photocatalytic material to ascorbic acid is 0.8:1, and the stirring is performed at 80°C for 1.5 h. The finally obtained MOF-derived MoO3 photocatalytic material is denoted as MOF MoO31.5h.
[0036] Example 3
[0037] The difference between the preparation method of the MOF-derived MoO3 photocatalytic material described in this example and that of Example 1 is that in step (1), the heating is performed at 90°C for 12 h, and after cooling to room temperature, a white sample is taken out. In step (3), the stirring is performed at 70°C for 0.5 h, and a dark blue sample is taken out. The finally obtained MOF-derived MoO3 photocatalytic material is denoted as MOF MoO30.5h.
[0038] Example 4
[0039] A preparation method of a MOF-derived MoO3 photocatalytic material, comprising the following steps:
[0040] (1) 2 mol of MoO3 and 1.2 mol of 2-methylimidazole were weighed and dissolved in 200 mL of deionized water, and then ultrasonic treatment was performed for 10 min. Subsequently, the solution was transferred to a 250 mL three-necked flask, and then heated at 120°C for 8 h. After cooling to room temperature, a white sample was taken out, washed with deionized water for 3 times by centrifugation, washed with ethanol for 2 times by centrifugation, dried at 70°C, and finally ground in an agate mortar for 3 min to obtain a Mo-MOF precursor sample powder.
[0041] (2) The Mo-MOF precursor prepared in step (1) above was placed on a crucible cover and placed in a muffle furnace, and then heated at a temperature increasing rate of 5°C / min at 500°C for 6 h. After cooling to room temperature, a sky blue sample was taken out, and then ground in an agate mortar for 10 min to obtain a MOF-derived MoO3 photocatalytic material.
[0042] (3) The MOF-derived MoO3 photocatalytic material prepared in step (2) above was mixed with ascorbic acid and deionized water, and then placed on a heating table and stirred at 50°C for 6 h. A dark blue sample was taken out, washed with deionized water for 3 times by centrifugation, washed with ethanol for 2 times by centrifugation, dried at 70°C, and finally ground in an agate mortar for 10 min to obtain a MOF-derived MoO3 photocatalytic material, which was recorded as MOF MoO36h.
[0043] Example 5
[0044] A method for preparing a MOF-derived MoO3 photocatalytic material, comprising the following steps:
[0045] (1) 2 mol of MoO3 and 5.2 mol of 2-ethylimidazole were weighed and dissolved in 200 mL of deionized water, and then ultrasonic treatment was performed for 10 min. Subsequently, the solution was transferred to a 250 mL three-necked flask, and then heated at 80°C for 16 h. After cooling to room temperature, a white sample was taken out, washed with deionized water for 3 times by centrifugation, washed with ethanol for 2 times by centrifugation, dried at 70°C, and finally ground in an agate mortar for 3 min to obtain a Mo-MOF precursor sample powder.
[0046] (2) The Mo-MOF precursor prepared in step (1) above was placed on a crucible cover and placed in a muffle furnace, and then heated at a temperature increasing rate of 3°C / min at 300°C for 3 h. After cooling to room temperature, a sky blue sample was taken out, and then ground in an agate mortar for 10 min to obtain a MOF-derived MoO3 photocatalytic material.
[0047] (3) The MOF-derived MoO3 photocatalytic material prepared in step (2) above is mixed with ascorbic acid and deionized water, the mass ratio of the MOF-derived MoO3 photocatalytic material to ascorbic acid is 2.0:1, and 15 ml of deionized water is used. The mixture is placed on a heating table and stirred at 90°C for 4 h, and a dark blue sample is taken out. The sample is washed by centrifugation with deionized water for 3 times and then washed by centrifugation with ethanol for 2 times. The sample is dried at 70°C, and finally the sample is ground in an agate mortar for 10 min to obtain the MOF-derived MoO3 photocatalytic material, which is denoted as MOF-MoO34h.
[0048] Figure 1 The XRD pattern of the photocatalytic material prepared in Example 1-3 and Comparative Example 1 shows that the MOF-derived MoO3 photocatalytic material in Example 1-3 has an orthorhombic phase, and the formation of oxygen defects does not change the phase of the material. Compared with the MOF-derived MoO3 photocatalytic material in Comparative Example 1, the (110) peak shifts to a larger angle, and the shift amount increases with the increase of the reduction treatment time. The oxygen vacancy defects on the (110) plane increase, and the compression amount of the crystal along the (110) direction increases.
[0049] Figure 2 The SEM pattern of the photocatalytic material prepared in Example 3 shows that the MOF-derived MoO3 photocatalytic material has a rod-like morphology formed by flakes, and the diameter is 500 nm to 3 μm. The MOF-derived MoO3 photocatalytic materials prepared in Examples 2-5 also have a rod-like morphology formed by flakes, and the diameter is 500 nm to 3 μm. With the increase of the treatment time, the rod-like morphology gradually peels off into a flake-like morphology.
[0050] The specific surface area of the MOF-derived MoO3 photocatalytic material prepared in Example 1 is 12.3745 m 2 / g, which is significantly increased compared with the specific surface area of Comparative Example 1.
[0051] According to Figure 4 It can be seen that, compared with the MOF-derived MoO3 photocatalytic material prepared in Comparative Example 1, the MOF-derived MoO3 photocatalytic materials prepared in Examples 1-3 have good light absorption in the visible light and near-infrared light, which solves the disadvantage that MoO3 only absorbs ultraviolet light.
[0052] Comparative Example 1
[0053] A preparation method of a MOF-derived MoO3 photocatalytic material, comprising the following steps:
[0054] (1) 2 mol MoO3 and 2 mol imidazole were weighed and dissolved in 200 mL of deionized water, and ultrasonic treatment was performed for 10 min. Then the solution was transferred to a 250 mL three-necked flask, and heated at 100°C for 12 h. After cooling to room temperature, the white sample was taken out, washed with deionized water by centrifugation for 3 times, washed with ethanol by centrifugation for 2 times, dried at 70°C, and finally ground in an agate mortar for 3 min to obtain a Mo-MOF precursor sample powder.
[0055] (2) The Mo-MOF precursor prepared in step (1) above was placed on the crucible cover and placed in a muffle furnace, and heated at 450°C for 4 h at a heating rate of 3°C / min. After cooling to room temperature, the sky blue sample was taken out and ground in an agate mortar for 10 min to obtain a MOF-derived MoO3 photocatalytic material.
[0056] The obtained MOF-derived MoO3 photocatalytic material is of orthorhombic system, retains the structure of Mo-MOF, and exists in the form of micrometer and nanometer sized flaky or rod-shaped structures, and the surface is not smooth, and is in the form of flaky stacked porous rods.
[0057] Comparative Example 2
[0058] A method for preparing a hydrothermal MoO3 photocatalytic material, comprising the following steps:
[0059] 0.4 mmol of ammonium molybdate and 25 mL of deionized water were mixed, 5 mL of HNO3 was added, and the mixture was stirred and mixed uniformly. Then the solution was transferred to a 50 mL polytetrafluoroethylene high-pressure reaction kettle, and heated at 180°C for 22 h. After cooling to room temperature, the sample was taken out, washed with deionized water by centrifugation for 3 times, washed with ethanol by centrifugation for 2 times, dried at 70°C, and finally ground in an agate mortar for 10 min to obtain a hydrothermal MoO3 sample powder, which is denoted as hydrothermal MoO3.
[0060] The hydrothermal MoO3 photocatalytic material is of orthorhombic system, and is in the form of rod-shaped structures with a length of tens of micrometers and a width of several hundred nanometers. It is different from the MOF-derived MoO3 in that it is a rod with a smooth surface, rather than a flaky stacked rod.
[0061] Comparative Example 3
[0062] A method for preparing a hydrothermal MoO3 photocatalytic material, comprising the following steps:
[0063] The hydrothermal MoO3 prepared in Comparative Example 2 was mixed with ascorbic acid and deionized water, with a mass ratio of MoO3 to ascorbic acid of 1:1 and 15 ml of deionized water, and placed on a heating table, stirred at 70°C for 2.5 h, and a dark blue sample was taken out. The sample was washed by centrifugation with deionized water for 3 times, and then washed by centrifugation with ethanol for 2 times, dried at 70°C, and finally ground in an agate mortar for 10 min to obtain a MoO3 photocatalytic material, which is denoted as hydrothermal MoO32.5h.
[0064] The obtained hydrothermal MoO32.5h photocatalytic material is of an orthorhombic crystal system and a rod-like structure, and there are more small-sized rod-like structures compared with the hydrothermal MoO3.
[0065] Example 1
[0066] The materials prepared in the examples and comparative examples were subjected to a photocatalytic CO2 reduction simulation experiment.
[0067] 30 mg of the photocatalytic material was dispersed in a 30 mm diameter petri dish and placed in a PARR gas-solid reaction vessel, and 99.99% pure CO2 was used as the CO2 source, and the gas atmosphere was H2:CO2 = 1:6. Each group of experiments was irradiated for 3 hours using a 300 W xenon lamp. The full spectrum was obtained by ultraviolet-visible-infrared full reverse reflection sheet. The gaseous products were evaluated by gas chromatography (GC), and the results are shown in Table 1. After each photocatalytic cycle, the photocatalyst on the quartz plate was collected, washed and dried for next use.
[0068] Table 1
[0069]
[0070] According to Examples 1-3, as the reduction treatment time increases, the catalytic effect of CO2 is significantly increased, and the reduction selectivity of CO is also increased. This is because as the treatment time increases, the content of oxygen vacancy defects increases, providing a larger specific surface area and more reduction reaction sites. In addition, the formation of oxygen vacancies increases the adsorption energy of CO2 and reduces the adsorption energy of CO, and makes the intermediate (COOH*) of CO2 to CO in the reaction process more stable, thereby improving the selectivity of CO generated in the reduction of CO2.
[0071] According to Examples 1-5 and Comparative Examples 1-3, the CO production and selectivity in the examples are much higher than those in Comparative Examples 1-3, the CO production reaches 14.9-20.3 μmol g -1 h -1 , the production of CH4 reaches 0.17-0.46 μmol g -1 h -1 , and the selectivity of CO is 96.99-99.10%.
[0072] According to the embodiments 1 and the comparative examples 1-3, it can be seen that both MOF derivation and oxygen vacancy construction can improve the reducibility of CO2, and they have a synergistic effect, the morphology structure obtained by MOF derivation is more conducive to the construction of oxygen vacancy defects, and further improves the reducibility of CO2.
[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.
Claims
1. The application of a MOF-derived MoO3 photocatalytic material in the photocatalytic reduction of CO2, characterized in that, The MOF-derived MoO3 photocatalytic material is obtained by sequentially calcining and reducing Mo-MOF materials to obtain MoO3 materials containing oxygen vacancies. The preparation method of the MOF-derived MoO3 photocatalytic material includes the following steps: (1) Molybdenum trioxide, organic framework and water were mixed and refluxed to obtain Mo-MOF precursor; the Mo-MOF precursor was calcined in a muffle furnace to obtain MOF-derived MoO3 photocatalyst. (2) Mix MOF-derived MoO3 photocatalyst, ascorbic acid and water, and heat and stir at 50~90℃ for 0.2~6h to obtain MOF-derived MoO3 photocatalytic material; The molar ratio of molybdenum trioxide to organic framework is (0.5-1.2):(0.7-1.3); the mass ratio of MOF-derived MoO3 photocatalyst to ascorbic acid is 0.5-2.
2. The application as described in claim 1, characterized in that, The organic framework is imidazole, 2-methylimidazolium, or 2-ethylimidazolium.
3. The application as described in claim 1, characterized in that, The condensation reflux temperature is 80~120℃, and the time is 8~16h.
4. The application as described in claim 1, characterized in that, The calcination treatment is carried out at a temperature of 300~500℃ for 3~6 hours, with a heating rate of 1~5℃ / min, and the atmosphere is air.