Monoclinic phase bi4v o4 and monoclinic phase bi6o5 (oh) 3 (no3) 5 (h2o) 3 two-phase coexisting high regular micron rod and preparation method thereof

Abstract

The application discloses a monoclinic phase BiVO4 and monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrod and a preparation method thereof. The method uses analytical pure bismuth nitrate pentahydrate Bi(NO3)3.5H2O and analytical pure ammonium metavanadate NH4VO3 as raw materials, distilled water as a solvent, and analytical pure 1-butyl-3-methyl imidazole bromide BMIMBr or analytical pure polyethylene glycol PEG as a surfactant, and prepares the monoclinic phase BiVO4 and monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrod through a simple microwave irradiation technology. The monoclinic phase BiVO4 and monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrod prepared by the method has high crystallinity, high specific surface area and high-regularity morphology size, and the preparation process is simple, is suitable for large-scale preparation, and provides a technical basis for development of a new semiconductor catalyst. The monoclinic phase BiVO4 and monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 prepared by the microwave irradiation method form a heterostructure, can reduce the recombination rate of electrons and holes, and is of great significance for improving the photocatalytic activity of BiVO4.

Description

Technical Field

[0001] This invention relates to a highly ordered microrod with two phases coexisting, namely monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3, and its preparation method, belonging to the field of photocatalytic functional materials. Background Technology

[0002] In recent years, energy depletion and environmental pollution have become increasingly serious problems, and the development and utilization of new secondary energy sources have gradually attracted people's attention. Photocatalysis technology, due to its advantages such as low cost and no pollution, has been widely used to utilize solar energy to degrade pollutants, produce hydrogen through photocatalytic water splitting, and reduce carbon dioxide through photocatalysis, and has gradually become one of the effective ways to solve the energy crisis and environmental pollution (REBlankenship, DMT Tiede, J. Barber, et al. Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement[J]. Science, 2011, 332(6031): 805-809). In the field of photocatalysis, the type of photocatalyst is the key factor determining its photocatalytic performance. Among them, semiconductor materials such as titanium dioxide (TiO2) have attracted widespread attention from researchers due to their good chemical stability, low toxicity, and low cost, and have been widely used as photocatalytic materials. However, TiO2 photocatalysts have a large band gap energy (Eg = 3.2 eV), resulting in low utilization of natural or artificial visible light, which limits their application in photocatalysis and environmental pollution control (X. Pan, Y. Zhao, S. Liu, et al. Comparing graphene-TiO2 nanowire and graphene-TiO2 nanoparticle composite photocatalysts[J]. ACS Applied Materials & Interfaces, 2012, 4(8): 3944-3950.). Therefore, developing and utilizing novel, highly active semiconductor photocatalytic materials and realizing their practical applications in daily life has gradually become a key task in the field of photocatalysis.

[0003] Bismuth vanadate (BiVO4) is a novel n-type semiconductor material. Initially used in coatings for rubber products, plastic products, paints, and printing inks (Xia Yin. Development Status and Trends of Polarized Microscopy in Pigment Research [J]. Cultural Relics Protection and Archaeological Science, 2008, 20(S1): 131-135), recent studies have found that the band gap of BiVO4 can be adjusted between 2.4 and 2.9 eV, and is close to the center of the solar spectrum at 2.6 eV, exhibiting excellent optical properties and photocatalytic performance (Y. Lin, C. Lu, C. Wei. Microstructure and photocatalytic performance of BiVO4 prepared by hydrothermal method [J]. Journal of Alloys and Compounds, 2019, 781: 56-63.). In addition, BiVO4 is chemically stable, non-polluting, green, and low-cost, and is widely used in photocatalytic degradation of pollutants and photocatalytic water splitting for hydrogen and oxygen production (S. Dong, J. Feng, Y. Li, et al. Shape-controlled synthesis). of BiVO4 hierarchical structures with unique natural-sunlight-driven photocatalytic activity[J]. Applied Catalysis B: Environmental, 2014, 152: 413-424.). Currently, BiVO4 mainly has three different crystal structures: monoclinic scheelite (ms-BiVO4), tetragonal scheelite (ts-BiVO4), and tetragonal zircon (tz-BiVO4). BiVO4 materials with different crystal structures have different properties and photocatalytic performance. BiVO4 materials with different structures can be prepared according to actual needs and give full play to their respective functions (A. Kudo, K. Omori, H. Kato. A novel aqueous process for preparation of crystal form-controlled and highly crystalline BiVO4 powder from layered vanadates at room temperature and its photocatalytic and photophysical properties[J]. Journal of the American Chemical Society, 1999, 121(49): 11459-11467.).Therefore, the rapid, efficient, and morphology-controllable preparation methods for BiVO4 materials with different structures and phases are of great significance for leveraging their optical properties and photocatalytic performance, and have potential application value and broad research value in the field of photocatalytic materials. Furthermore, forming a heterostructure with basic bismuth nitrate can greatly enhance the visible light harvesting ability of BiVO4 materials (Shen Jie, Li Zhongfu, Zhang Shiying. Basic bismuth nitrate and bismuth oxyiodide composite photocatalysts and their preparation methods and applications [P]. 201910540596.7, 2019.06.21). However, preparing BiVO4 and basic bismuth nitrate two-phase coexistence materials that can form heterostructures remains a significant challenge. Summary of the Invention

[0004] The purpose of this invention is to propose a highly ordered microrod with two phases coexisting, namely monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3, prepared by a simple microwave radiation technique, and its synthesis method.

[0005] This invention is implemented using the following scheme:

[0006] 1. A method for preparing highly ordered microrods with monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 coexisting, characterized in that: the method for preparing highly ordered microrods with monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 coexisting uses analytically pure 1-butyl-3-methylimidazolium bromide (BMIMBr) as a surfactant;

[0007] The standard card number for the monoclinic phase BiVO4 is 14-0688, and the standard card number for the monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 is 70-1226.

[0008] The high-order microrods with the coexistence of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 have a length of 3.95–16.95 μm and a width of 1.03–4.64 μm.

[0009] Its preparation method includes the following steps:

[0010] a. Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 1.3974 g of analytical grade 1-butyl-3-methylimidazole bromide, and add them sequentially to 115 mL of distilled water at room temperature (25 °C). Then, stir the mixture for 15 min at 800 rpm to ensure complete dissolution and obtain a homogeneous mixed solution A.

[0011] b. Accurately weigh 0.7457 g of analytical grade ammonium metavanadate, add it to 85 mL of distilled water at room temperature (25 °C), and then stir it for 15 min at 800 rpm with a magnetic stirrer to fully dissolve it, so as to obtain a homogeneous solution B. Place it in a 500 mL round bottom three-necked flask for later use.

[0012] c. Place the 500mL round-bottom three-necked flask containing solution B from step b into a Midea PJ21C-AU microwave oven equipped with an atmospheric pressure reflux device. Add solution A from step a dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature is 50-100℃, the power is 500-700W, the frequency is 2.45GHz, and the reflux condenser is activated. Microwave the reaction until the last drop is added.

[0013] d. Turn on the microwave oven reactor again. The microwave oven temperature is 50-100℃, the power is 500-700W, the frequency is 2.45GHz, and the reflux condenser is started. The reaction continues for 110-130 minutes, and then it is allowed to cool naturally to room temperature at 25℃.

[0014] e. Transfer the solution cooled to room temperature in step d to a clean and dried 30 mL centrifuge tube, centrifuge for 2 min in a Xiangyi H1650 centrifuge at 5000 rpm, then filter to obtain a precipitate. Wash the precipitate 5-10 times with deionized water and 2-3 times with analytical grade ethanol. Collect the solid and dry it in a 70℃ oven for 24 h to obtain a high-order microrod with two phases coexisting: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3.

[0015] 2. A highly ordered microrod with monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 coexisting two phases and its preparation method, characterized in that: the preparation method of the highly ordered microrod with monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 coexisting two phases uses analytical grade polyethylene glycol (PEG) as a surfactant;

[0016] The standard card number for the monoclinic phase BiVO4 is 14-0688, and the standard card number for the monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 is 70-1226.

[0017] The high-order microrods with the coexistence of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 have a length of 2.94–19.42 μm and a width of 0.58–4.16 μm.

[0018] Its preparation method includes the following steps:

[0019] f. Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 1-10 g of analytical grade polyethylene glycol, and add them sequentially to 115 mL of distilled water at room temperature (25 °C). Then, stir the mixture for 15 min at 800 rpm to ensure complete dissolution and obtain a homogeneous mixed solution A.

[0020] g. Accurately weigh 0.7457 g of analytical grade ammonium metavanadate, add it to 85 mL of distilled water at room temperature (25 °C), and then stir it for 15 min at 800 rpm with a magnetic stirrer to fully dissolve it, so as to obtain a homogeneous solution B. Place it in a 500 mL round bottom three-necked flask for later use.

[0021] h. Place the 500mL round-bottom three-necked flask containing solution B from step g into a Midea PJ21C-AU microwave oven equipped with an atmospheric pressure reflux device. Add solution A from step f dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature is 50-100℃, the power is 500-700W, the frequency is 2.45GHz, and the reflux condenser is activated. Microwave the reaction until the last drop is added.

[0022] i. Turn on the microwave oven reactor again. The microwave oven temperature is 50-100℃, the power is 500-700W, the frequency is 2.45GHz, and the reflux condenser is started. The reaction continues for 150 minutes, and then it is allowed to cool naturally to room temperature at 25℃.

[0023] j. Transfer the solution cooled to room temperature in step i to a clean and dried 30 mL centrifuge tube, centrifuge for 2 min in a Xiangyi H1650 centrifuge at 5000 rpm, then filter to obtain a precipitate. Wash the precipitate 5-10 times with deionized water and 2-3 times with analytical grade ethanol. Collect the solid and dry it in a 70℃ oven for 24 h to obtain a high-order microrod with two phases coexisting: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3.

[0024] Furthermore, in steps a and b, the molar ratio of analytically pure bismuth nitrate pentahydrate Bi(NO3)3·5H2O, 1-butyl-3-methylimidazolium bromide BMIMMBr, and ammonium metavanadate NH4VO3 is 2:3:3.

[0025] Furthermore, in steps f and g, the molar ratio of analytically pure bismuth nitrate pentahydrate Bi(NO3)3·5H2O, analytically pure polyethylene glycol PEG, and ammonium metavanadate NH4VO3 is 1:0.0001 to 0.001:1.5.

[0026] In a highly ordered microrod containing both monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 phases, the monoclinic BiVO4 (JCPDS-ICDD: 14-0688) phase has a peak percentage of 50.00%–85.91%, and its cell parameters are as follows: α=γ=90° and β=90.38°, space group I2 / a(15), its strongest peak corresponds to the monoclinic phase BiVO4 (JCPDS-ICDD: 14-0688). The crystal plane has a lattice spacing of 0.309 nm; the peak percentage of the monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1266) is 14.09%–50%, and the cell parameters are as follows. and α=γ=90.0° and β=127.83°.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] 1. This invention utilizes the role of surfactants to prepare highly ordered monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting highly ordered microrods using a simple microwave irradiation method. The preparation process is simple and efficient, and the post-processing is simple, making it suitable for large-scale preparation. This provides a good technical foundation for the photocatalytic application of bismuth vanadate.

[0029] 2. The blended monoclinic phase BiVO4 and monoclinic phase Bi6O5(OH)3(NO3)5(H2O)3 prepared by the present invention can form a heterojunction structure, reduce the recombination rate of electrons and holes, and thus greatly improve the photocatalytic activity.

[0030] 3. The blended monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 microrods prepared by this invention have high regularity and are expected to promote practical applications in photocatalysis.

[0031] Microwave radiation is a novel heating method widely used in chemical reactions, offering advantages such as high selectivity, low energy consumption, cleanliness, and high yield, making it a highly efficient heating method. PEG is a nonionic surfactant that inhibits the aggregation of BiVO4 particles by having different parts of its molecule adhere to the gas-liquid interface. In this process, both phases are considered as components of BiVO4 crystal nuclei, and PEG molecules are arranged between the BiVO4 crystal nuclei, effectively transferring into the interior of the PEG molecules, ultimately inducing the formation of a well-dispersed product with a specific morphology. Simultaneously, the morphology of the product is highly dependent on the amount of PEG used. When the PEG concentration is too high or too low, phenomena such as non-micelle formation or particle aggregation may occur, thus affecting the synthesis of BiVO4. Therefore, under microwave radiation, and with specific parameters such as PEG dosage, reactant concentration, and temperature, this patented method can controllably synthesize monoclinic BiVO4 microtubes. Attached Figure Description

[0032] Figure 1 X-ray diffraction (XRD) patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 110 min.

[0033] Figure 2 The XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 110 min show the proportion of each phase in the samples.

[0034] Table 1 shows the proportion of each phase in the XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 110 min.

[0035] Figure 3 The crystal structure diagram of monoclinic BiVO4 (JCPDS-ICDD: 14-0688);

[0036] Figure 4 The crystal structure diagram of monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1226);

[0037] Figure 525kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 130 min.

[0038] Figure 6 4kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 110 min.

[0039] Figure 7 Schematic diagram of the synthesized morphology of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with two coexisting phases;

[0040] Figure 8 X-ray diffraction (XRD) patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 130 min.

[0041] Figure 9 The XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 130 min show the proportion of each phase in the samples.

[0042] Table 2 shows the proportion of each phase in the XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 130 min.

[0043] Figure 10 13kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 110 min.

[0044] Figure 11 13kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a molar ratio of Bi:BMIMBr:V of 2:3:3 and a microwave reaction time of 130 min.

[0045] Figure 12 X-ray diffraction (XRD) patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.0001:1.5 and a microwave reaction time of 150 min.

[0046] Figure 13 The XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.0001:1.5 and a microwave reaction time of 150 min show the proportion of each phase in the samples.

[0047] Table 3 shows the proportion of each phase in the XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.0001:1.5 and a microwave reaction time of 150 min.

[0048] Figure 14 5kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.0001:1.5 and a microwave reaction time of 150 min.

[0049] Figure 15 10kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.0001:1.5 and a microwave reaction time of 150 min.

[0050] Figure 16 X-ray diffraction (XRD) patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.001:1.5 and a microwave reaction time of 150 min.

[0051] Figure 17 The XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.001:1.5 and a microwave reaction time of 150 min show the proportion of each phase in the samples.

[0052] Table 4 shows the proportion of each phase in the XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.001:1.5 and a microwave reaction time of 150 min.

[0053] Figure 18 4kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.001:1.5 and a microwave reaction time of 150 min.

[0054] Figure 19 25kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.001:1.5 and a microwave reaction time of 150 min.

[0055] Figure 20 X-ray diffraction (XRD) patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.01:1.5 and a microwave reaction time of 150 min.

[0056] Figure 21 The XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.01:1.5 and a microwave reaction time of 150 min show the proportion of each phase in the samples.

[0057] Table 5 shows the proportion of each phase in the XRD patterns of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.01:1.5 and a microwave reaction time of 150 min.

[0058] Figure 22 7kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.01:1.5 and a microwave reaction time of 150 min.

[0059] Figure 2313kx scanning electron microscope (SEM) images of monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 samples with a Bi:PEG:V molar ratio of 1:0.01:1.5 and a microwave reaction time of 150 min. Detailed Implementation

[0060] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0061] Example 1:

[0062] (1) Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 1.3974 g of analytical grade 1-butyl-3-methylimidazole bromide, and add them sequentially to 115 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to ensure complete dissolution and obtain a homogeneous mixed solution A. (2) Accurately weigh 0.7457 g of analytical grade ammonium metavanadate, and add it to 85 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to ensure complete dissolution and obtain a homogeneous solution B. Place the solution B in a 500 mL round-bottom three-necked flask for later use. (3) Place the 500 mL round-bottom three-necked flask containing solution B from step (2) into a Midea PJ21C-AU microwave oven equipped with a normal pressure reflux device. Add solution A from step (1) dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature was 100℃, the power was 700W, the frequency was 2.45GHz and the reflux condenser was started. The microwave reaction continued until the last drop was added. (4) The microwave oven reactor was turned on again. The microwave oven temperature was 100℃, the power was 700W, the frequency was 2.45GHz and the reflux condenser was started. The reaction continued for 110 minutes and then cooled naturally to room temperature at 25℃. (5) The solution cooled to room temperature in step (4) was transferred to a clean and dried 30mL centrifuge tube and centrifuged for 2 minutes in a Xiangyi H1650 centrifuge with a speed of 5000rpm. Then the precipitate was obtained by filtration. The precipitate was washed 10 times with deionized water and 2 times with analytical grade ethanol. The solid was collected and dried in a 70℃ oven for 24 hours to obtain a high-order microrod with two phases coexisting: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3.

[0063] Depend on Figure 1X-ray diffraction results showed that the synthesized product consisted of two phases: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3. The characteristic peaks at 2θ = 18.669°, 18.988°, 28.586°, 28.822°, 28.947°, 30.548°, and 46.711° were similar to those of monoclinic BiVO4 (JCPDS-ICDD: 14-0688) at (110) and (011) Å. The peak percentages corresponding to the (121), (040), and (240) crystal planes are 76.39%. Figure 2 Table 1), the unit cell parameters are as follows: α = γ = 90.0° and β = 90.38°, space group I2 / a, crystal plane indices corresponding to the strongest peak are The lattice spacing is 0.309 nm, and the crystal structure is as follows: Figure 3 As shown; simultaneously, at 2θ = 6.519 ° 10.030 ° 11.291 ° 11.511 ° 11.634 ° 20.141 ° and 23.170 ° The characteristic peak at the location is similar to that of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1226) (100), The peak percentages corresponding to the (011), (110), (211), and (202) crystal planes are 23.61%. Figure 2 Table 1), the unit cell parameters are as follows: α=γ=90.0° and β=127.83°, space group P21 / c, crystal structure as follows Figure 4 As shown; Scanning electron microscope (SEM) image ( Figure 5 , 6 This indicates that the product is a microrod with a length of 3.95–11.25 μm and a width of 1.31–2.97 μm, as shown in the schematic diagram below. Figure 7 As shown.

[0064] Example 2:

[0065] (1) Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 1.3974 g of analytical grade 1-butyl-3-methylimidazole bromide, and add them sequentially to 115 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to ensure complete dissolution and obtain a homogeneous mixed solution A. (2) Accurately weigh 0.7457 g of analytical grade ammonium metavanadate, and add it to 85 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to ensure complete dissolution and obtain a homogeneous solution B. Place the solution B in a 500 mL round-bottom three-necked flask for later use. (3) Place the 500 mL round-bottom three-necked flask containing solution B from step (2) into a Midea PJ21C-AU microwave oven equipped with a normal pressure reflux device. Add solution A from step (1) dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature was 100℃, the power was 700W, the frequency was 2.45GHz and the reflux condenser was started. The microwave reaction continued until the last drop was added. (4) The microwave oven reactor was turned on again. The microwave oven temperature was 100℃, the power was 700W, the frequency was 2.45GHz and the reflux condenser was started. The reaction continued for 130 minutes and then cooled naturally to room temperature at 25℃. (5) The solution cooled to room temperature in step (4) was transferred to a clean and dried 30mL centrifuge tube and centrifuged for 2 minutes in a Xiangyi H1650 centrifuge with a speed of 5000rpm. Then the precipitate was obtained by filtration. The precipitate was washed 10 times with deionized water and 2 times with analytical grade ethanol. The solid was collected and dried in a 70℃ oven for 24 hours to obtain a high-order microrod with two phases coexisting: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3.

[0066] Depend on Figure 8 X-ray diffraction results showed that the synthesized product consisted of two phases: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3. The characteristic peaks at 2θ = 18.988°, 28.586°, 28.822°, 28.947°, 30.548°, 39.782°, and 47.305° were similar to those of monoclinic BiVO4 (JCPDS-ICDD: 14-0688) (011). The peak percentages corresponding to the (121), (040), (211), and (042) crystal planes are 50.00%. Figure 9 (Table 2), the unit cell parameters are α = γ = 90.0° and β = 90.38°, space group I2 / a, crystal plane indices corresponding to the strongest peak are The lattice spacing is 0.309 nm, and the crystal structure is as follows: Figure 3 As shown; simultaneously, at 2θ = 6.519° 10.030 ° 11.162°, 11.634 ° 12.616 ° 17.878 ° and 21.935 ° The characteristic peak at the location is similar to that of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1226) (100), (110), (002) and Corresponding to the crystal plane, its peak percentage is 50.00% ( Figure 9 (Table 2), the unit cell parameters are α=γ=90.0° and β=127.83°, space group P21 / c, crystal structure as follows Figure 4 As shown; Scanning electron microscope (SEM) image ( Figure 10 , 11 This indicates that the product is a microrod with a length of 4.24–16.95 μm and a width of 1.03–4.64 μm, as shown in the schematic diagram below. Figure 7 As shown.

[0067] Example 3:

[0068] (1) Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 1 g of analytical grade polyethylene glycol. Add them sequentially to 115 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to fully dissolve the bismuth nitrate, resulting in a homogeneous mixed solution A. (2) Accurately weigh 0.7457 g of analytical grade ammonium metavanadate. Add it to 85 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to fully dissolve the ammonium metavanadate, resulting in a homogeneous solution B. Place the solution B in a 500 mL round-bottom three-necked flask for later use. (3) Place the 500 mL round-bottom three-necked flask containing solution B from step (2) into a Midea PJ21C-AU microwave oven equipped with a normal pressure reflux device. Add solution A from step (1) dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature is [temperature missing]. 100℃, power of 700W, frequency of 2.45GHz and start the reflux condenser, microwave reaction until the last drop is added; (4) turn on the microwave oven reactor again, microwave oven temperature of 100℃, power of 700W, frequency of 2.45GHz and start the reflux condenser, continue the reaction for 150min, and then cool naturally to room temperature at room temperature of 25℃; (5) transfer the solution cooled to room temperature in step (4) to a clean and dried 30mL centrifuge tube, centrifuge for 2min in a Xiangyi H1650 centrifuge with a speed of 5000rpm, then filter to obtain precipitate, wash the precipitate 10 times with deionized water and 2 times with analytical grade ethanol, collect the solid and dry it in a 70℃ oven for 24h to obtain monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-order microrods.

[0069] Depend on Figure 12 X-ray diffraction results showed that the synthesized product consisted of two phases: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3. The characteristic peaks at 2θ = 8.669°, 28.586°, 28.822°, 28.947°, 34.494°, 35.221°, and 50.314° were similar to those of monoclinic BiVO4 (JCPDS-ICDD: 14-0688) (110). The peak percentages corresponding to the (121), (200), (002), and (202) crystal planes are 67.75%. Figure 13 (Table 3), the cell parameters are as follows: α = γ = 90.0° and β = 90.38°, space group I2 / a, crystal plane indices corresponding to the strongest peak are The lattice spacing is 0.309 nm, and the crystal structure is as follows: Figure 3 As shown; simultaneously, at 2θ = 6.519 °10.030°, 13.919 ° 14.857 ° 17.878 ° 22.615 ° and 23.170 ° The characteristic peak at the location is similar to that of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1226) (100), Corresponding to crystal planes (121) and (202), their peak percentage is 32.25%. Figure 13 (Table 3), the cell parameters are as follows: α=γ=90.0° and β=127.83°, space group P21 / c, crystal structure as follows Figure 4 As shown; Scanning electron microscope (SEM) image ( Figure 14 , 15 This indicates that the product is a microrod with a length of 4.92–19.42 μm and a width of 1.03–4.10 μm, as shown in the schematic diagram below. Figure 7 As shown.

[0070] Example 4:

[0071] (1) Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 2 g of analytical grade polyethylene glycol. Add them sequentially to 115 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to fully dissolve the bismuth nitrate, resulting in a homogeneous mixed solution A. (2) Accurately weigh 0.7457 g of analytical grade ammonium metavanadate. Add it to 85 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to fully dissolve the ammonium metavanadate, resulting in a homogeneous solution B. Place the solution B in a 500 mL round-bottom three-necked flask for later use. (3) Place the 500 mL round-bottom three-necked flask containing solution B from step (2) into a Midea PJ21C-AU microwave oven equipped with a normal pressure reflux device. Add solution A from step (1) dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature is [temperature missing]. 100℃, power of 700W, frequency of 2.45GHz and start the reflux condenser, microwave reaction until the last drop is added; (4) turn on the microwave oven reactor again, microwave oven temperature of 100℃, power of 700W, frequency of 2.45GHz and start the reflux condenser, continue the reaction for 150min, and then cool naturally to room temperature at room temperature of 25℃; (5) transfer the solution cooled to room temperature in step (4) to a clean and dried 30mL centrifuge tube, centrifuge for 2min in a Xiangyi H1650 centrifuge with a speed of 5000rpm, then filter to obtain precipitate, wash the precipitate 10 times with deionized water and 2 times with analytical grade ethanol, collect the solid and dry it in a 70℃ oven for 24h to obtain monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-order microrods.

[0072] Depend on Figure 16 X-ray diffraction results showed that the synthesized product consisted of two phases: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3. The characteristic peaks at 2θ = 18.669°, 28.586°, 28.822°, 35.221°, 40.040°, 42.339°, and 49.960° were similar to those of monoclinic BiVO4 (JCPDS-ICDD: 14-0688) (110). (002) (150) and Corresponding to the crystal plane, its peak percentage is 85.91% ( Figure 17 (Table 4), the cell parameters are as follows: α = γ = 90.0° and β = 90.38°, space group I2 / a, crystal plane indices corresponding to the strongest peak are The lattice spacing is 0.309 nm, and the crystal structure is as follows: Figure 3As shown; simultaneously, the characteristic peaks at 2θ = 6.519°, 10.030°, 11.634°, 12.616°, 13.919°, 25.559° and 27.770° are similar to those of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1226) (100), (110), (002) Corresponding to the (415) crystal plane, its peak percentage is 14.09%. Figure 17 (Table 4), the cell parameters are as follows: α=γ=90.0° and β=127.83°, space group P21 / c, crystal structure as follows Figure 4 As shown; Scanning electron microscope (SEM) image ( Figure 18 , 19 This indicates that the product is a microrod with a length of 3.36–15.22 μm and a width of 0.73–4.16 μm, as shown in the schematic diagram below. Figure 7 As shown.

[0073] Example 5:

[0074] (1) Accurately weigh 2.0615 g of analytical grade bismuth nitrate pentahydrate and 10 g of analytical grade polyethylene glycol. Add them sequentially to 115 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to fully dissolve the bismuth nitrate, resulting in a homogeneous mixed solution A. (2) Accurately weigh 0.7457 g of analytical grade ammonium metavanadate. Add it to 85 mL of distilled water at room temperature (25°C). Then, stir the mixture for 15 min at 800 rpm to fully dissolve the ammonium metavanadate, resulting in a homogeneous solution B. Place the solution B in a 500 mL round-bottom three-necked flask for later use. (3) Place the 500 mL round-bottom three-necked flask containing solution B from step (2) into a Midea PJ21C-AU microwave oven equipped with a normal pressure reflux device. Add solution A from step (1) dropwise into solution B. Turn on the microwave oven when adding the first drop. The microwave oven temperature is [temperature missing]. 100℃, power of 700W, frequency of 2.45GHz and start the reflux condenser, microwave reaction until the last drop is added; (4) turn on the microwave oven reactor again, microwave oven temperature of 100℃, power of 700W, frequency of 2.45GHz and start the reflux condenser, continue the reaction for 150min, and then cool naturally to room temperature at room temperature of 25℃; (5) transfer the solution cooled to room temperature in step (4) to a clean and dried 30mL centrifuge tube, centrifuge for 2min in a Xiangyi H1650 centrifuge with a speed of 5000rpm, then filter to obtain precipitate, wash the precipitate 10 times with deionized water and 2 times with analytical grade ethanol, collect the solid and dry it in a 70℃ oven for 24h to obtain monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-order microrods.

[0075] Depend on Figure 20 X-ray diffraction results showed that the synthesized product consisted of two phases: monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3. The characteristic peaks at 2θ = 18.988°, 28.822°, 28.947°, 30.548°, 39.545°, 42.464°, and 53.310° were similar to those of monoclinic BiVO4 (JCPDS-ICDD: 14-0688) (011). The peak percentages corresponding to the (121), (040), (141), (051), and (161) crystal planes are 83.19%. Figure 21 (Table 5), the cell parameters are as follows: α = γ = 90.0° and β = 90.38°, space group I2 / a, crystal plane indices corresponding to the strongest peak are The lattice spacing is 0.309 nm, and the crystal structure is as follows: Figure 3As shown; simultaneously, the characteristic peaks at 2θ = 6.519°, 11.511°, 25.389°, 27.209°, 28.746°, 29.972° and 31.049° are similar to the (100), (011), (004), (014) peaks of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1226). and Corresponding to the crystal plane, its peak percentage is 16.81% ( Figure 21 (Table 5), the cell parameters are as follows: α=γ=90.0° and β=127.83°, space group P21 / c, crystal structure as follows Figure 4 As shown; Scanning electron microscope (SEM) image ( Figure 22 , 23 This indicates that the product is a microrod with a length of 2.94–11.74 μm and a width of 0.58–3.09 μm, as shown in the schematic diagram below. Figure 7 As shown.

[0076] The above descriptions are merely five embodiments of the present invention, and not all embodiments. Any equivalent modifications made by those skilled in the art to the technical solutions of the present invention by reading the present invention specification are covered by the claims of the present invention.

[0077] Comparative Example 1:

[0078] In (L. Chen, SFYin, R. Huang, Q. Zhang, SLLuo, CTAu. Hollow peanut-like m-BiVO4: facile synthesis and solar-light-induced photocatalytic property[J], CrystEngComm, 2012, 14, 4217-4222), Chen et al. synthesized peanut-like hollow m-BiVO4 using 1-lysine as a surfactant. The specific operation was as follows: 0.4 g of 1-lysine was dissolved in 40 mL of distilled water, and then 1.17 g of NH4VO3 (10 mmol) was added and stirred for 1 h to obtain an emulsion solution (named solution A). 4.85 g (10 mmol) of Bi(NO3)35H2O was dissolved in 40 mL of ethylene glycol (EG) and stirred to obtain a transparent solution (named solution B). Then, solution B was added dropwise to solution A and stirred continuously to obtain a yellow substance (suspension). The mixture was transferred to a 100 mL PTFE autoclave and maintained at the selected temperature (120, 160, or 200 °C) for 24 h. The autoclave was then cooled to room temperature (RT), the solids were collected by filtration, washed several times with deionized water and anhydrous ethanol, and dried in air at 80 °C for 4 h. The collected sample was then dried at 3 °C for 1 min. -1 The mixture is heated to a selected temperature (350, 450 or 550 °C) on a temperature ramp and calcined at this temperature for 3 hours to obtain m-BiVO4 with a peanut-like hollow structure.

[0079] The method, innovation, and technical effects disclosed in this invention are fundamentally different from those of the comparative example.

[0080] Comparative Example 2:

[0081] In (XJWang,HLLiu,XLWan,JRWang,LLChang. Additive-free solvothermal synthesis of peanut-like BiVO4 powders with enhanced photocatalysis activity. Crystal Research and Technology. 2013, 48, 1066-1072), Wang et al. synthesized peanut-like BiVO4 powders via a solvothermal method. The specific procedure was as follows: 1 mmol Bi(NO3)3·5H2O and 1 mmol NH4VO3 were dissolved in 5 mL glacial acetic acid and 55 mL 2 mol / L NH3·H2O solution, respectively. Each solution was stirred at room temperature for 1 h. After both solutions clarified, the two mixtures were combined in a 1:1 molar ratio and stirred for 1 h to obtain a stable, salmon-pink homogeneous solution. The resulting suspension was then transferred to an 80 mL polytetrafluoroethylene-lined autoclave and maintained at 180 °C for 12 h. After the product was naturally cooled to room temperature in an autoclave, it was collected, washed several times with deionized water and anhydrous alcohol, and then dried at 70°C for 12 hours to obtain peanut-shaped BiVO4.

[0082] The method, innovation, and technical effects disclosed in this invention are fundamentally different from those of the comparative example.

[0083] Comparative Example 3:

[0084] (Shang Jun, Chen Tingzhen, Huang Guo, Wang Xianwei, Zhou Fei, Ma Yimeng, Feng Gang. A method for preparing a gray basic bismuth nitrate photocatalyst material with visible light response. 201711058898.8, 2017.11.01.) In this paper, Shang et al. prepared a gray basic bismuth nitrate photocatalyst material Bi6O5(OH)3(NO3)5(H2O)3 with visible light response. The specific operation is as follows: (1) Place 4.85g of bismuth nitrate pentahydrate in a beaker and add deionized water. Stir the beaker with a magnetic stirrer at 400n / Stir at a rate of min for 60 min, let stand at room temperature, rinse repeatedly until the solution is neutral, take out the precipitate and place it in a drying oven at 100℃ for 150 min to obtain the hydrolysis product white powder material; (2) Place 0.65 g of the obtained hydrolysis product white powder material in a beaker and add deionized water, stir on a magnetic stirrer and irradiate with a 300W mercury lamp for 30 min, let stand, pour off the upper clear liquid, and heat the remaining product in a water bath to dry to obtain the target product gray basic bismuth nitrate photocatalytic material with visible light response.

[0085] The method, innovation, and technical effects disclosed in this invention are fundamentally different from those of the comparative example.

Claims

1. A method for preparing a highly ordered microrod with both monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 phases coexisting, characterized in that: The preparation method of the monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrods adopts analytical pure 1-butyl-3-methyl imidazole bromide BMIMBr as a surfactant; The standard card number of the monoclinic BiVO4 is 14-0688, and the standard card number of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 is 70-1226; The length of the monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrods is 3.95-16.95 μm, and the width is 1.03-4.64 μm; The preparation method comprises the following steps: a. accurately weigh 2.0615 g of analytical pure bismuth nitrate pentahydrate and 1.3974 g of analytical pure 1-butyl-3-methyl imidazole bromide, and add them into 115 mL of distilled water at room temperature 25 ℃, and then stir them in a magnetic stirrer at a speed of 800 rpm for 15 min to make them fully dissolved, to obtain a uniform mixed solution A; b. accurately weigh 0.7457 g of analytical pure ammonium metavanadate, and add it into 85 mL of distilled water at room temperature 25 ℃, and then stir it in a magnetic stirrer at a speed of 800 rpm for 15 min to make it fully dissolved, to obtain a uniform solution B, which is placed in a 500 mL round-bottom three-necked flask for standby; c. place the 500 mL round-bottom three-necked flask containing solution B in step b in a Midea PJ21C-AU microwave oven with a normal-pressure reflux device, and add solution A in step a drop by drop into solution B, and start the microwave oven when the first drop is added, the microwave oven temperature is 50-100 ℃, the power is 500-700 W, the frequency is 2.45 GHz, and the reflux condensing device is started, and the microwave reaction is continued until the last drop is added; d. start the microwave oven reactor again, the microwave oven temperature is 50-100 ℃, the power is 500-700 W, the frequency is 2.45 GHz, and the reflux condensing device is started, and the reaction is continued for 110-130 min, and then the solution is naturally cooled to room temperature at room temperature 25 ℃; e. transfer the solution cooled to room temperature in step d to a washed and dried 30 mL centrifuge tube, centrifuge it in a centrifuge with a model of Xiangyin H1650 and a speed of 5000 rpm for 2 min, and then filter the precipitate to obtain a precipitate, wash the precipitate with deionized water for 5-10 times, and wash it with analytical pure ethanol for 2-3 times, collect the solid, and dry it in a 70 ℃ oven for 24 h to obtain the monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrods.

2. A method for preparing a monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrod, characterized in that: The preparation method of the monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrods adopts analytical pure polyethylene glycol (PEG) as a surfactant; in steps f and g, the molar ratio of analytical pure bismuth nitrate pentahydrate Bi(NO3)3·5H2O, analytical pure polyethylene glycol (PEG) and ammonium metavanadate NH4VO3 is 1:0.0001-0.001:1.5; The standard card number of the monoclinic BiVO4 is 14-0688, and the standard card number of the monoclinic Bi6O5(OH)3(NO3)5(H2O)3 is 70-1226. The length of the monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrods is 2.94-19.42 μm, and the width is 0.58-4.16 μm. The preparation method comprises the following steps: f. accurately weigh 2.0615 g of analytical pure bismuth nitrate pentahydrate and 1-10 g of analytical pure polyethylene glycol (PEG), and then add them into 115 mL of distilled water at room temperature 25°C, and then stir them in a magnetic stirrer at a speed of 800 rpm for 15 min to make them fully dissolved, to obtain a uniform mixed solution A; g. accurately weigh 0.7457 g of analytical pure ammonium metavanadate, and then add it into 85 mL of distilled water at room temperature 25°C, and then stir it in a magnetic stirrer at a speed of 800 rpm for 15 min to make it fully dissolved, to obtain a uniform solution B, which is placed in a 500 mL round-bottom three-necked flask for standby; h. place the 500 mL round-bottom three-necked flask containing solution B in step g in a Midea PJ21C-AU microwave oven with a normal-pressure reflux device, and then add solution A in step f into solution B drop by drop, and start the microwave oven when the first drop is added, and the microwave oven temperature is 50-100°C, the power is 500-700 W, the frequency is 2.45 GHz, and the reflux condensing device is started, and the microwave reaction is continued until the last drop is added; i. start the microwave oven reactor again, the microwave oven temperature is 50-100°C, the power is 500-700 W, the frequency is 2.45 GHz, and the reflux condensing device is started, and the reaction is continued for 150 min, and then the solution is naturally cooled to room temperature at room temperature 25°C; j. transfer the solution cooled to room temperature in step i into a washed and dried 30 mL centrifuge tube, centrifuge it in a centrifuge with a model of Xiangyin H1650 and a speed of 5000 rpm for 2 min, and then filter the precipitate to obtain a precipitate, wash the precipitate with deionized water for 5-10 times, and then wash it with analytical pure ethanol for 2-3 times, collect the solid, and then dry it in a 70°C oven for 24 h to obtain the monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrods.

3. The method for preparing monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high regular micron rods according to claim 1, characterized in that: In steps a and b, the molar ratio of analytical pure bismuth nitrate pentahydrate Bi(NO3)3·5H2O, 1-butyl-3-methyl imidazole bromide (BMIMBr) and ammonium metavanadate NH4VO3 is 2:3:

3.

4. The monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 two-phase coexisting high-regularity microrod according to any one of claims 1-3, characterized in that: The sample prepared belongs to blended monoclinic BiVO4 and monoclinic Bi6O5(OH)3(NO3)5(H2O)3 powder by powder XRD diffraction analysis of the sample; the peak value of monoclinic BiVO4 (JCPDS-ICDD: 14-0688) accounts for 50.00% to 85.91%, and the cell parameters are α=γ=90° and β=90.38°, and the space group is I2 / a (15), and the strongest peak corresponds to the crystal face of monoclinic BiVO4 (JCPDS-ICDD: 14-0688), and the lattice spacing is 0.309 nm; the peak value of monoclinic Bi6O5(OH)3(NO3)5(H2O)3 (JCPDS-ICDD: 70-1266) accounts for 14.09% to 50%, and the cell parameters are and α=γ=90.0° and β=127.83°.

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