A BiOBr 0.875 I 0.125 / TiO2 photocatalyst and preparation method and application thereof

Abstract

The application discloses a BiOBr 0.875 I 0.125 / TiO2 photocatalyst and a preparation method and application thereof, bismuth salt powder is dissolved in acetic acid and deionized water to obtain liquid A; anatase TiO2, KBr powder and KI powder are mixed, deionized water is added to the mixture, and ultrasonic dispersion is performed to uniformly disperse TiO2 particles in the aqueous solution to obtain liquid B; liquid B is added dropwise into liquid A, and stirring is continuously performed to fully react and age the mixture to obtain a suspension; a molar ratio of bismuth in the bismuth salt, bromine in the KBr and iodine in the KI is 1:0.875:0.125; the suspension is left to stand to remove supernatant, and the precipitate is centrifuged, washed, dried and ground to obtain BiOBr 0.875 I 0.125 / TiO2 photocatalyst. The BiOBr 0.875 I 0.125 / TiO2 photocatalyst and the preparation method and application thereof, and the prepared BiOBr 0.875 I 0.125 / TiO2 heterojunction has excellent visible light response photocatalytic activity and stability, the degradation efficiency of the BiOBr 0.875 I 0.125 / TiO2 on a rhodamine B solution can reach 45%, which is much higher than that of TiO2, and is also higher than that of BiOBr 0.875 I 0.125 +TiO2 group.

Description

Technical Field

[0001] This invention relates to the field of photocatalyst technology, and in particular to a BiOBr... 0.875 I 0.125 / TiO2 photocatalysts, their preparation methods, and applications. Background Technology

[0002] Photocatalysis utilizes a catalyst to generate photogenerated electrons and holes with high redox capabilities under specific light source irradiation, achieving efficient degradation of organic pollutants and hydrogen production. TiO2, as a representative n-type semiconductor photocatalyst, exhibits excellent photocatalytic degradation of pollutants and hydrogen production performance under ultraviolet light, and has attracted widespread attention due to its good photochemical stability, lack of secondary pollution, and low cost. However, TiO2 is a wide-bandgap (3.2 eV) semiconductor material with a weak response to visible light and low light energy utilization (only 5% of the solar spectrum); at the same time, the easy recombination of photogenerated electrons and holes in TiO2 further limits the industrialization process of TiO2.

[0003] Modification of TiO2 is a key factor in improving its photocatalytic performance. The overall photocatalytic efficiency mainly depends on factors such as band gap, carrier separation and transport, and energy conversion. Currently employed modification methods include morphology control, metal and non-metal doping, and heterojunction formation. Among these, forming heterojunctions with other substances is an effective method for modifying TiO2. Patent CN115487799A discloses a lithium strontium titanate / titanium dioxide heterojunction photocatalyst, constructing a heterojunction composite structure to improve the performance of SrLi2Ti6O2. 14 The / TiO2 band structure enhances charge separation efficiency, and combined with its specific microscopic hollow spherical structure, this makes SrLi2Ti6O 14 / TiO2 photocatalyst has the performance of highly efficient photocatalytic hydrogen production.

[0004] In recent years, bismuth halogen oxide nanomaterials (BiOX, X = Cl, Br, I) have been extensively studied for their excellent visible light response, unique crystal and electronic structure, and chemical stability in the construction of heterojunction photocatalysts. Currently, there are studies on using BiOX to composite with TiO2 to improve the reactivity of TiO2 under visible light. The prepared composite photocatalysts have shown excellent performance in degrading organic pollutants, photoelectric response, and hydrogen production through water electrolysis. However, no research has been found on BiOBr... x I 1-x Research on / TiO2. Summary of the Invention

[0005] The purpose of this invention is to provide a BiOBr 0.875 I 0.125This paper presents a method for preparing and applying TiO2 photocatalysts to address the limitations of existing methods for modifying TiO2 by constructing heterojunctions.

[0006] To achieve the above objectives, the first aspect of the present invention provides a BiOBr 0.875 I 0.125 The preparation method of / TiO2 photocatalyst includes the following steps:

[0007] (1) Dissolve bismuth salt powder in acetic acid and deionized water to obtain solution A;

[0008] (2) Mix anatase TiO2, KBr powder and KI powder, add deionized water, and ultrasonically disperse the mixture to make TiO2 particles uniformly dispersed in the aqueous solution to obtain solution B.

[0009] (3) Add liquid B dropwise to liquid A, continue stirring to allow it to react fully and age, and obtain a suspension;

[0010] The molar ratio of bismuth in bismuth salt, bromine in KBr, and iodine in KI is 1:0.875:0.125.

[0011] (4) Allow the suspension to stand to remove the supernatant, centrifuge, wash, dry, and grind the precipitate to obtain BiOBr. 0.875 I 0.125 / TiO2 photocatalyst.

[0012] Preferably, the bismuth salt in step (1) is Bi(NO3)3·5H2O, the amount of bismuth salt added is 0.312g, the amount of acetic acid added is 3ml, and the amount of deionized water added is 30ml.

[0013] Preferably, in step (2), the amount of anatase TiO2 added is 4.6g, the amount of KBr powder added is 0.0670g, the amount of KI powder added is 0.0134g, and the amount of deionized water added is 60ml.

[0014] Preferably, the ultrasound time in step (2) is 5-10 min.

[0015] Preferably, the stirring time in step (3) is 6 hours and the aging time is 6 hours.

[0016] Preferably, in step (4), the centrifugal speed is 8000 r / min, the vacuum drying temperature is 100℃, the drying time is 12h, and the dried powder is ground in a mortar and pestle for later use.

[0017] A second aspect of the present invention provides a BiOBr prepared by the preparation method described above. 0.875 I 0.125 / TiO2 photocatalyst.

[0018] Preferably, TiO2 and BiOBr 0.875 I 0.125 The mass ratio is 23:1.

[0019] A third aspect of the present invention provides a BiOBr 0.875 I 0.125 / Application of TiO2 photocatalyst in the degradation of pollutant Rhodamine B.

[0020] Therefore, the present invention adopts a BiOBr with the above-described structure. 0.875 I 0.125 / TiO2 photocatalyst, its preparation method and application, have the following beneficial effects:

[0021] (1) BiOBr was successfully synthesized at room temperature by chemical precipitation. 0.875 I 0.125 In the / TiO2 complex, a pn-type heterojunction is formed at the interface between the two compounds. The morphology of this heterojunction is based on BiOBr. 0.875 I 0.125 Irregular aggregates composed of nanosheets and TiO2 particles. High-resolution XPS analysis of the elemental spectra of Bi, Ti, O, Br, and I in the composite, combined with ESR results, revealed BiOBr... 0.875 I 0.125 Oxygen vacancies exist in TiO2.

[0022] (2)BiOBr 0.875 I 0.125 / TiO2 heterojunctions exhibit excellent visible-light-responsive photocatalytic activity and stability. Using RhB as the target pollutant, after a reaction under visible light irradiation for 30 min, BiOBr... 0.875 I 0.125 TiO2 can achieve a degradation efficiency of up to 45% for Rhodamine B solution, which is much higher than that of TiO2 and also higher than that of BiOBr. 0.875 I 0.125 +TiO2 group. Photodegradation experiments verified the promoting effect of heterojunction formation on photocatalytic activity enhancement. Compared to pure TiO2, BiOBr... 0.875 I 0.125 / TiO2 heterojunction photocatalysts exhibit a wider light response range and superior photocatalytic activity. 0.875 I 0.125 The TiO2 heterojunction photocatalyst maintained a high and stable photodegradation efficiency even after five photocatalytic cycle experiments.

[0023] (3) Further analysis using DRS, PL, ESR, and XPS revealed the true nature of BiOBr.0.875 I 0.125 / TiO2 heterojunction visible light photocatalysis mechanism: BiOBr with a narrow bandgap 0.875 I 0.125 A novel photocatalyst, BiOBr, is formed by constructing a heterojunction between TiO2 (Eg = 3.10 eV) and TiO2 (Eg = 1.88 eV). 0.875 I 0.125 The band gap (Eg = 2.94 eV) of / TiO2 is significantly lower than that of TiO2, and BiOBr 0.875 I 0.125 The addition of [a specific component] extended the photoresponse range of TiO2, with the absorption sideband expanding from 400 nm to 470 nm. BiOBr 0.875 I 0.125 The TiO2 heterojunction effectively promotes the separation between photogenerated carriers, thereby further improving quantum efficiency; BiOBr 0.875 I 0.125 Oxygen vacancies are formed during the preparation of the TiO2 heterojunction, which helps to narrow the band gap, increase the concentration of photogenerated carriers, and promote the separation of photogenerated carriers, thereby further enhancing the photocatalytic activity.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 These are the XRD patterns of Example 1, Comparative Example 1, and TiO2;

[0026] Figure 2 These are SEM images of Example 1 and Comparative Example 1;

[0027] Figure 3 These are EDS elemental analysis diagrams of Example 1 and Comparative Example 1;

[0028] Figure 4 These are the nitrogen adsorption-desorption isotherms of Example 1, Comparative Example 1, and TiO2;

[0029] Figure 5 These are XPS images of Example 1, Comparative Example 1, and TiO2;

[0030] Figure 6 These are the high-resolution XPS spectra of Bi 4f from Example 1 and Comparative Example 1;

[0031] Figure 7 These are the high-resolution XPS spectra of O1s for Example 1 and Comparative Example 1;

[0032] Figure 8 These are high-resolution XPS spectra of Ti 2p from Example 1 and Comparative Example 1;

[0033] Figure 9 These are the ESR spectra of Example 1, Comparative Example 1, and TiO2;

[0034] Figure 10 Examples 1, 1 Comparative Example, TiO2, and BiOBr are mentioned. 0.875 I 0.125 Photodegradation efficiency of Rhodamine B by photocatalysts mixed with TiO2;

[0035] Figure 11 This is a cyclic degradation diagram of Rhodamine B by the photocatalyst in Example 1;

[0036] Figure 12 These are the UV-Vis diffuse reflectance spectra and bandgap diagrams of Example 1, Comparative Example 1, and TiO2;

[0037] Figure 13 When the excitation wavelength is 325nm, BiOBr, BiOI, and BiOBr 0.875 I 0.125 BiOBr 0.875 I 0.125 / TiO2 and TiO2 at room temperature photoluminescence spectrum;

[0038] Figure 14 It is TiO2 and BiOBr 0.875 I 0.125 Band structure and BiOBr 0.875 I 0.125 / Schematic diagram of the generation and transfer process of charge carriers in TiO2 heterojunction. Detailed Implementation

[0039] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0040] Example 1

[0041] BiOBr 0.875 I 0.125 The preparation method of / TiO2 photocatalyst includes the following steps:

[0042] Solution A: Weigh 0.312g of Bi(NO3)3·5H2O powder and dissolve it in 3ml of acetic acid and 30ml of deionized water;

[0043] Solution B: Weigh 4.6g of anatase TiO2 (P25), 0.0670g of KBr powder and 0.0134g of KI powder, mix the three powders, add 60ml of deionized water, and sonicate for 5 minutes to make TiO2 (P25) particles uniformly dispersed in the aqueous solution.

[0044] After solution A has completely clarified, solution B is added dropwise to solution A, and magnetic stirring continues for 6 hours to allow for complete reaction and aging. After 6 hours, the pale yellow suspension is allowed to stand for a few minutes, the supernatant is discarded, and the precipitate is transferred to a 10ml centrifuge tube. The mixture is centrifuged at 8000 rpm and washed three times with deionized water for 10 minutes each time. The washed powder is then placed in a vacuum drying oven and dried at 100℃ for 12 hours. The dried powder yields TiO2 and BiOBr. 0.875 I 0.125 BiOBr with a mass ratio of 23:1 0.875 I 0.125 / TiO2, grind it in a mortar and pestle and set it aside for later use.

[0045] Comparative Example 1

[0046] BiOBr 0.875 I 0.125 The preparation method of photocatalyst includes the following steps:

[0047] Weigh 3.1202g of Bi(NO3)3·5H2O powder into a beaker, add 5ml of acetic acid and 50ml of deionized water to the beaker, and stir magnetically to completely dissolve the Bi(NO3)3·5H2O powder.

[0048] Weigh 0.6699 g of KBr powder and 0.1335 g of KI powder. Mix KBr and KI and dissolve them in a small amount of deionized water. Add the KBr and KI mixture dropwise to Bi(NO3)3·5H2O solution, resulting in a yellow turbidity. Continue magnetic stirring for 6 hours to allow for complete reaction and aging. After 6 hours, let the yellow suspension stand for a few minutes, discard the supernatant, and transfer the yellow precipitate to a 10 ml centrifuge tube. Centrifuge at 8000 rpm and wash three times with deionized water for 10 minutes each time. Place the washed powder in a vacuum drying oven and dry under vacuum at 100℃ for 12 hours. Remove the dried BiOBr powder. 0.875 I 0.125 Grind it in a mortar and pestle and set aside for later use.

[0049] Comparative Example 2

[0050] The preparation method of BiOBr / TiO2 photocatalyst includes the following steps:

[0051] Solution A: Weigh 0.312g of Bi(NO3)3·5H2O powder and dissolve it in 3ml of acetic acid and 30ml of deionized water;

[0052] Solution B: Weigh 4.6g of anatase TiO2 (P25) and 0.0765g of KBr powder, mix the two powders, add 60ml of deionized water, and sonicate for 5 minutes to make TiO2 (P25) particles uniformly dispersed in the aqueous solution.

[0053] After solution A has completely clarified, solution B is added dropwise to solution A, and magnetic stirring continues for 6 hours to allow for complete reaction and aging. After 6 hours, the pale yellow suspension is allowed to stand for a few minutes, the supernatant is discarded, and the precipitate is transferred to a 10ml centrifuge tube. The mixture is centrifuged at 8000 rpm and washed three times with deionized water for 10 minutes each time. The washed powder is then placed in a vacuum drying oven and dried at 100℃ for 12 hours. The dried powder is then ground in a mortar and pestle for later use.

[0054] Comparative Example 3

[0055] The preparation method of BiOI / TiO2 photocatalyst includes the following steps:

[0056] Solution A: Weigh 0.312g of Bi(NO3)3·5H2O powder and dissolve it in 3ml of acetic acid and 30ml of deionized water;

[0057] Solution B: Weigh 4.6g of anatase TiO2 (P25) and 0.1068g of KI powder, mix the two powders, add 60ml of deionized water, and sonicate for 5 minutes to make TiO2 (P25) particles uniformly dispersed in the aqueous solution.

[0058] After solution A has completely clarified, solution B is added dropwise to solution A, and magnetic stirring continues for 6 hours to allow for complete reaction and aging. After 6 hours, the pale yellow suspension is allowed to stand for a few minutes, the supernatant is discarded, and the precipitate is transferred to a 10ml centrifuge tube. The mixture is centrifuged at 8000 rpm and washed three times with deionized water for 10 minutes each time. The washed powder is then placed in a vacuum drying oven and dried at 100℃ for 12 hours. The dried powder is then ground in a mortar and pestle for later use.

[0059] Experimental Example 1

[0060] The catalysts prepared in Example 1 and Comparative Example 1 were characterized by XRD, SEM, EDS, BET, and XPS.

[0061] (1) The crystal phase of the prepared sample powder was analyzed by XRD. Figure 1 Includes BiOBr 0.875 I0.125 TiO2 and BiOBr 0.875 I 0.125 XRD patterns of the TiO2 photocatalyst, and standard diffraction patterns of BiOBr (JCPDS 09-0393), BiOI (JCPDS10-0445), and anatase TiO2 (JCPDS21-1272). 0.875 I 0.125 The main diffraction peaks are located at 2θ = 10.58°, 25.00°, 31.32°, and 32.16°. Compared with the standard diffraction pattern of BiOBr, the crystal planes corresponding to these diffraction peaks are (001), (101), (102), and (110), respectively. For BiOBr... 0.875 I 0.125 The formation of [a specific type of Br] can be understood as the result of a certain amount of Br being replaced by I in the BiOBr crystal. Therefore, influenced by the doping of I, BiOBr [a specific type of Br]... 0.875 I 0.125 Some diffraction peaks of BiOBr show a significant redshift compared to BiOBr, indicating lattice distortion with a tendency to increase in size. 0.875 I 0.125 The diffraction peaks at 2θ = 33.98° and 43.66° correspond to the standard diffraction peaks of BiOI. Furthermore, in BiOBr... 0.875 I 0.125 BiOBr can be observed in / TiO2. 0.875 I 0.125 The diffraction peaks of both the TiO2 and BiOBr phases coexist. The diffraction peaks at 2θ of 36.96°, 37.76°, 38.54°, 48.02°, and 62.66° belong to anatase titanium dioxide and correspond to the (103), (004), (112), (200), and (204) crystal planes, respectively. These results all indicate that BiOBr... 0.875 I 0.125 and BiOBr 0.875 I 0.125 Successful synthesis of TiO2 photocatalyst.

[0062] (2) Figure 2 It is BiOBr 0.875 I 0.125 and BiOBr 0.875 I 0.125 Scanning electron microscope (SEM) images of the / TiO2 complex at different magnifications. From Figure 2 (a) It can be seen that BiOBr 0.875 I 0.125 The particles are microspheres, with a diameter of approximately 5 μm. As the magnification increases, from... Figure 2From (b) and (c), we can see that BiOBr 0.875 I 0.125 The microspheres have a hierarchical structure and are assembled from a large number of nanosheets with a diameter of 400–600 nm.

[0063] In addition, by Figure 2 (d) It can be found that BiOBr 0.875 I 0.125 The microstructure of TiO2 shows that it is composed of irregular aggregates. From... Figure 2 As can be observed in (e) and (f), these aggregates are composed of two different types of nanosheets and 3D bulk particles. In BiOBr 0.875 I 0.125 In the TiO2 scanning electron microscope image, the nanosheet structure and BiOBr 0.875 I 0.125 The morphology is consistent with that of titanium dioxide, and the overall state of the 3D blocky particles and irregular aggregates is consistent with that of titanium dioxide.

[0064] (3) Energy-dispersive X-rays (EDS) were used to study BiOBr. 0.875 I 0.125 and BiOBr 0.875 I 0.125 The elemental composition and distribution of the TiO2 heterojunction photocatalyst were determined. Figure 3 As shown in (b)-(e), BiOBr 0.875 I 0.125 The EDS plot of the compound shows that BiOBr 0.875 I 0.125 The photocatalyst is composed of Ti, O, Bi, Br, and I elements, and each element has a specific composition relative to BiOBr. 0.875 I 0.125 The microspheres are uniformly distributed. (BiOBr) 0.875 I 0.125 The elemental content results of the composite material are as follows: Figure 3 As shown in (f), the molar ratio of Bi:O:Br:I is 31.26:32.98:30.62:5.13, which is within the error range and close to that of BiOBr. 0.875 I 0.125 The theoretical ratio is 8:8:7:1. From... Figure 3 (h)-(l) shows that BiOBr 0.875 I 0.125 The TiO2 heterojunction material contains Ti, O, Bi, Br, and I elements, with Ti and O being the main components. The other elements are present in BiOBr. 0.875 I 0.125 The / TiO2 heterojunction material exhibits uniform distribution. The above EDS results further demonstrate that BiOBr...0.875 I 0.125 and BiOBr 0.875 I 0.125 Successful synthesis of / TiO2 heterojunction photocatalyst.

[0065] (4) Sample BiOBr 0.875 I 0.125 BiOBr 0.875 I 0.125 / TiO2 and N2 adsorption-desorption isotherms of TiO2 are as follows Figure 4 As shown. According to the classification of adsorption isotherms by the International Union of Pure and Applied Chemistry (IUPAC), BiOBr 0.875 I 0.125 BiOBr 0.875 I 0.125 The N2 adsorption-desorption isotherms of TiO2 and TiO2 powder belong to type IV isotherms. Hysteresis loops appear in the medium-high pressure region (0.4–1.0 relative pressure), and the pore size distribution is concentrated in the mesopore region. Furthermore, BiOBr... 0.875 I 0.125 BiOBr 0.875 I 0.125 The hysteresis loops of both TiO2 and TiO2 belong to the H3 type, indicating that they are slit holes formed between stacked thin sheets.

[0066] BiOBr 0.875 I 0.125 BiOBr 0.875 I 0.125 The specific surface area and pore volume data of / TiO2 and TiO2 are shown in Table 1. Combining the data in Table 1, it can be found that: BiOBr 0.875 I 0.125 The specific surface area of ​​TiO2 heterojunction photocatalysts is smaller than that of BiOBr. 0.875 I 0.125 And TiO2, BiOBr 0.875 I 0.125 The pore size of TiO2 material is between that of BiOBr 0.875 I 0.125 Between and TiO2. Combining SEM results, BiOBr 0.875 I 0.125 In TiO2 materials, BiOBr 0.875 I 0.125 The nanosheets and TiO2 nanoparticles bind and overlap with each other, resulting in the synthesized BiOBr 0.875 I 0.125 The specific surface area of ​​the TiO2 material is reduced. Considering the hysteresis loop type, all three catalysts have pore types classified as slit pores. Therefore, compared to TiO2 microparticles, BiOBr... 0.875 I0.125 The nanosheets are relatively large and embedded between TiO2 particles, increasing the porosity between TiO2 particles and thus enhancing the BiOBr... 0.875 I 0.125 / TiO2 material has a larger pore volume; while compared to BiOBr 0.875 I 0.125 TiO2 particles are smaller than BiOBr particles. 0.875 I 0.125 Nanosheets, BiOBr 0.875 I 0.125 The porosity formed by the combination with TiO2 is higher than that of BiOBr. 0.875 I 0.125 The gaps in it are more compact, so BiOBr 0.875 I 0.125 / The pore volume of TiO2 material is smaller than that of BiOBr 0.875 I 0.125 The capacity of the hole.

[0067] Table 1 BiOBr 0.875 I 0.125 BiOBr 0.875 I 0.125 / TiO2 and TiO2 specific surface area and pore volume

[0068] Sample <![CDATA[S BET (m 2 / g)]]> <![CDATA[V pore (cm 3 / g)]]> <![CDATA[TiO2]]> 7.710 0.01871 <![CDATA[BiOBr 0.875 I 0.125 ]]> 8.121 0.03127 <![CDATA[BiOBr 0.875 I 0.125 / TiO2]]> 7.004 0.02305

[0069] (5)BiOBr 0.875 I 0.125 BiOBr 0.875 I 0.125 The XPS test results for / TiO2 and TiO2 are as follows: Figure 5 .Depend on Figure 5 It can be seen that BiOBr 0.875 I 0.125 The XPS spectrum of the sample showed peaks representing Bi 4f (159.12 eV), O 1s (529.98 eV), Br 3d (68.30 eV), and I 3d (618.93 eV). BiOBr 0.875 I 0.125 The overall spectrum of the / TiO2 sample showed peaks representing Ti 2p (458.68 eV), Bi 4f (158.99 eV), O1s (529.96 eV), Br 3d (68.17 eV), and I 3d (618.62 eV). XPS results indicated that BiOBr 0.875 I 0.125 and BiOBr 0.875 I 0.125 Successful synthesis of / TiO2 compounds.

[0070] Further research on BiOBr0.875 I 0.125 Peak fitting and discussion were performed on the high-resolution XPS spectra of each element in TiO2. Meanwhile, the results were compared with those of TiO2 or BiOBr. 0.875 I 0.125 The elements in the comparison are compared.

[0071] Figure 6 The high-resolution XPS spectrum of Bi4f shows typical spin-orbit duality splitting. For BiOBr... 0.875 I 0.125 / TiO2, the characteristic peaks appear at 159.00 eV and 164.29 eV, which belong to the 4f group of Bi, respectively. 7 / 2 and 4f 5 / 2 Peak; with BiOBr 0.875 I 0.125 Comparing the characteristic peak positions of 159.12 eV and 164.42 eV in the high-resolution spectrum of Bi4f, BiOBr 0.875 I 0.125 The red shift in / TiO2 was 0.12 eV and 0.13 eV, respectively, which can be attributed to the breaking of Bi-O bonds due to oxygen vacancies.

[0072] Figure 7 The high-resolution XPS spectrum of O1s shows three characteristic peaks at 529.91 eV, 531.18 eV, and 532.00 eV, corresponding to lattice oxygen, defect sites, and hydroxyl groups, respectively; while in BiOBr... 0.875 I 0.125 Only two characteristic peaks appear: lattice oxygen (529.91 eV) and hydroxyl oxygen (532.20 eV), with no oxygen defect peaks.

[0073] Figure 8 For BiOBr 0.875 I 0.125 High-resolution XPS image of TiO2 and Ti 2p, Ti 2p 1 / 2 and 2p 3 / 2 The peaks appeared at 464.41 eV and 458.69 eV, respectively. Compared to the high-resolution XPS spectrum of Ti 2p for TiO2, BiOBr... 0.875 I 0.125 Ti 2p in TiO2 composites 1 / 2 Peaks and Ti 2p 3 / 2 The obvious displacement further proves the relationship between TiO2 and BiOBr. 0.875 I 0.125 The interaction occurs between Bi and Ti atoms.

[0074] (6) XPS confirmed the presence of surface oxygen vacancies. Next, ESR characterization further revealed the role of oxygen vacancies in influencing BiOBr. 0.875 I 0.125 / The role of TiO2 in photocatalytic performance. For example Figure 9 As shown, BiOBr 0.875 I 0.125 The ESR spectrum of the sample showed almost no obvious signal response, indicating that there may be almost no oxygen vacancies present. For the pure TiO2 sample, a significant signal response was observed at a g-factor of 2.000. In contrast, the sample doped with a small amount of BiOBr... 0.875 I 0.125 BiOBr after 0.875 I 0.125 / TiO2 has a much higher peak intensity at the same g-factor, which means that BiOBr 0.875 I 0.125 The formation of numerous oxygen vacancies in the TiO2 sample. The generation of oxygen vacancies is accompanied by the formation of donor levels. The donor levels generated below the conduction band of titanium dioxide will reduce the potential for BiOBr. 0.875 I 0.125 The band gap of hybridized titanium dioxide leads to BiOBr 0.875 I 0.125 The light absorption edge of the / TiO2 material is expanded, which is related to Figure 12 The results are consistent with the analysis results of DRS spectroscopy; the presence of oxygen vacancies can also increase the concentration of photogenerated carriers and promote the separation of photogenerated carriers, which is beneficial to further improving photocatalytic activity.

[0075] Experimental Example 2

[0076] Example 1, TiO2, Comparative Example 1, and BiOBr 0.875 I 0.125 The photocatalytic activity of the mechanical mixture with TiO2 was tested.

[0077] Four photocatalysts, TiO2 and BiOBr, were investigated. 0.875 I 0.125 BiOBr 0.875 I 0.125 / TiO2 and BiOBr 0.875 I 0.125 Mechanical mixture with TiO2 (abbreviated as BiOBr) 0.875 I 0.125 The photocatalytic activity of Rhodamine B by TiO2 under visible light irradiation was evaluated by measuring its photodegradation efficiency. This experiment simulated visible light conditions using a 500W xenon lamp with a 420nm filter. Performance test results are shown below. Figure 10 As shown.

[0078] Depend on Figure 10 It can be observed that when 100 mg of each of the four catalysts is added to 100 ml of a 10 mg / L Rhodamine B solution, and the solution is irradiated with visible light for 30 min, the BiOBr... 0.875 I 0.125 The degradation efficiencies of TiO2 and BiOBr for RhB were 99% and 5.4%, respectively. A small amount of BiOBr was doped into TiO2. 0.875 I 0.125 Afterwards, the photodegradation efficiency was greatly improved. Similarly, after 30 minutes of visible light irradiation, BiOBr... 0.875 I 0.125 / TiO2 can achieve a photodegradation efficiency of 45% for Rhodamine B. That is, under the same conditions, the heterojunction photocatalyst BiOBr... 0.875 I 0.125 / TiO2 has more than 7 times the photocatalytic activity of pure TiO2.

[0079] In addition, to further verify BiOBr 0.875 I 0.125 The promoting effect of the heterostructure formed by TiO2 on the photocatalytic reaction was determined by setting an equal amount of BiOBr. 0.875 I 0.125 Mechanical mixture with TiO2 sample as BiOBr 0.875 I 0.125 / TiO2 control group, labeled as BiOBr 0.875 I 0.125 +TiO2. Under the same experimental conditions, after 30 minutes of visible light irradiation, BiOBr 0.875 I 0.125 The photodegradation efficiency of the +TiO2 group was only 12%, far lower than that of BiOBr. 0.875 I 0.125 / TiO2 is 45%. This indicates that BiOBr 0.875 I 0.125 In TiO2, the formation of heterojunctions plays a key and major role in enhancing photocatalytic activity.

[0080] Photocatalytic activity tests were conducted on comparative examples 2-3.

[0081] After 30 minutes of visible light irradiation, the catalysts prepared in Comparative Examples 2 and 3 showed degradation efficiencies of 30% and 25% for RhB, respectively. This is significantly lower than that of the BiOBr catalyst prepared in Example 1. 0.875 I 0.125 / TiO2 photodegradation efficiency of Rhodamine B. This indicates the efficiency of BiOBr. 0.875 I 0.125Compared with catalysts prepared by constructing heterojunctions with TiO2, catalysts prepared by combining BiOBr and BiOI with TiO2 have more advantages.

[0082] Experimental Example 3

[0083] The catalyst of Example 1 was subjected to stability testing.

[0084] The stability of catalysts is one of the important factors affecting their practical application. This was investigated by examining the recycling of BiOBr. 0.875 I 0.125 The effect of TiO2 on the photodegradation efficiency of Rhodamine B was evaluated to assess BiOBr. 0.875 I 0.125 The stability of the TiO2 heterojunction photocatalyst. Experimental results are as follows: Figure 11 As shown, BiOBr is used 5 times. 0.875 I 0.125 After applying TiO2, its degradation efficiency for Rhodamine B did not decrease; instead, it increased by 11%, indicating that the heterojunction photocatalyst BiOBr... 0.875 I 0.125 TiO2 has good stability and high recyclability.

[0085] The stability of the catalysts in Comparative Examples 1-3 was tested using the same method as described above.

[0086] The catalyst BiOBr prepared in Comparative Example 1 0.875 I 0.125 The degradation efficiency of Rhodamine B decreased significantly with increasing cycle number, which is highly detrimental to the subsequent utilization of the photocatalyst. The same phenomenon was observed in the BiOBr / TiO2 photocatalyst prepared in Comparative Example 2 and the BiOI / TiO2 photocatalyst prepared in Comparative Example 3; the degradation efficiency of Rhodamine B decreased with increasing cycle number. However, the photocatalyst BiOBr from Example 1... 0.875 I 0.125 / TiO2 increases the degradation efficiency of Rhodamine B with increasing cycle number, which has a positive impact on the subsequent utilization of photocatalysts and makes it more conducive to applying photocatalysts in actual production processes.

[0087] Test Example 4

[0088] The catalysts prepared in Example 1 and Comparative Example 1 were characterized by DRS and PL to further elucidate the BiOBr prepared in this invention. 0.875 I 0.125 / Photocatalytic mechanism of TiO2 heterojunction.

[0089] (1) The UV-Vis diffuse reflectance spectrum of the prepared sample is as follows: Figure 12As shown in (a). Due to their inherent band gap, the photocatalysts TiO2 and BiOBr... 0.875 I 0.125 The absorption sidebands are located at approximately 400 nm and 585 nm, respectively. Compared to TiO2, BiOBr... 0.875 I 0.125 The absorption sideband of / TiO2 shows a significant red shift, with the absorption sideband located around 470 nm. This indicates that BiOBr 0.875 I 0.125 / TiO2 has a stronger absorption capacity for visible light than pure TiO2, i.e., BiOBr 0.875 I 0.125 The addition of [a specific ingredient] improves the visible light response of TiO2.

[0090] The band gap widths of the three samples are calculated using the following formula: ɑhv=A(hv-E) g ) n / 2 (1)

[0091] In the formula: α - absorbance index, the numerical value is related to... Figure 12 In (a), the vertical coordinates are equal, h is Planck's constant, and its value is 6.63 × 10⁻⁶. -34 (J·s), v - frequency, v = c / λ, c = 3 × 10 8 m / s, λ is the wavelength (nm), A is a constant, E g - Semiconductor bandgap (eV), where the exponent n is determined by the type of semiconductor itself. Since they all belong to indirect bandgap semiconductors, TiO2 and BiOBr... 0.875 I 0.125 and BiOBr 0.875 I 0.125 The value of n for / TiO2 is set to 4. Then, the absorption coefficient (Ahv) is used. 1 / 2 The vertical axis represents the light energy system.

Claims

1. A type of BiOBr 0.875 I 0.125 The method for preparing TiO2 photocatalyst is characterized by: Includes the following steps: (1) Dissolve 0.312g Bi(NO3)3·5H2O in 3ml acetic acid and 30ml deionized water to obtain solution A; (2) Mix 4.6g of anatase TiO2, 0.0670g of KBr powder and 0.0134g of KI powder, add 60ml of deionized water, and ultrasonically disperse the TiO2 particles evenly in the aqueous solution to obtain solution B. (3) Add liquid B dropwise to liquid A, continue stirring for 6 hours to allow it to react fully, and then age for 6 hours to obtain a suspension; The molar ratio of bismuth in bismuth salt, bromine in KBr, and iodine in KI is 1:0.875:0.

125. (4) Allow the suspension to stand to remove the supernatant, centrifuge, wash, dry, and grind the precipitate to obtain BiOBr. 0.875 I 0.125 / TiO2 photocatalyst; BiOBr 0.875 I 0.125 The TiO2 photocatalyst is a pn heterojunction composed of irregular aggregates, which are made up of two different types of nanosheets and 3D bulk particles; BiOBr 0.875 I 0.125 / Oxygen vacancies exist in TiO2 photocatalysts.

2. A BiOBr according to claim 1 0.875 I 0.125 The method for preparing TiO2 photocatalyst is characterized by: The ultrasound time in step (2) is 5-10 min.

3. A BiOBr according to claim 1 0.875 I 0.125 The method for preparing TiO2 photocatalyst is characterized by: In step (4), the centrifugal speed is 8000 r / min, the vacuum drying temperature is 100℃, the drying time is 12h, and the dried powder is ground in a mortar and pestle for later use.

4. A BiOBr prepared by the preparation method according to any one of claims 1 to 3 0.875 I 0.125 / TiO2 photocatalyst.

5. A BiOBr according to claim 4 0.875 I 0.125 / TiO2 photocatalyst, characterized in that: TiO2 and BiOBr 0.875 I 0.125 The mass ratio is 23:

1.

6. A BiOBr according to claim 5 0.875 I 0.125 / Application of TiO2 photocatalyst in the degradation of pollutant Rhodamine B.

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