Copper porphyrin modified BiOBr / Bi19S27Br3 catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the field of photocatalysis, and particularly provides a copper porphyrin modified BiOBr / Bi19S27Br3 catalyst as well as a preparation method and application thereof. According to the catalyst, BiOBr / Bi19S27Br3 is successfully synthesized by a one-step solvothermal method, porphyrin copper is introduced to provide a high-strength active copper site, and under the condition that a cocatalyst and a sacrificial agent are not added, the photocatalytic CO2 reduction performance of optimized BBS-CT-2 is 3.5 times that of BiOBr / Bi19S27Br3. The work provides a special engineering strategy for surface charge transfer and development of a near-infrared light catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalysis, and particularly relates to a copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst, its preparation method and application. Background Art

[0002] According to existing research, BiOBr can only absorb visible light and its photocatalytic performance is poor. As is well known, visible light accounts for about 50% of the total energy of solar radiation. However, infrared light accounts for about 43%, and it can be considered that infrared light is as important as visible light. Therefore, it is the general trend to better utilize infrared light in the field of CO2 photocatalysis.

[0003] Bi 19 S 27 Br3, as a metal sulfide, is an extremely important narrow-bandgap semiconductor photocatalyst in Bi III -VII A -VI A and has a relatively high light response ability and sufficient negative band edge in the near-infrared region, ensuring its good application in the field of photocatalytic CO2 reduction. However, due to the narrow bandgap of Bi 19 S 27 Br3, it is difficult for photogenerated carriers to separate, seriously affecting its photocatalytic performance. 19 S 27 Br3's narrow bandgap makes it difficult for photogenerated carriers to separate, seriously affecting its photocatalytic performance.

[0004] According to electrocatalytic CO2 reduction, it has been fully demonstrated that copper is the main metal for converting CO2 into highly reduced products. Due to its special surface properties and excellent electronic conductivity, copper atoms have been developed for catalyzing the reduction of CO2. Porphyrin is an 18π electron heteroaromatic compound, and the aromatic nature of its tetrapyrrole group and the functional groups on its side chains determine its rich chemical properties. At the same time, the porphyrin unit has a strong chelating coordination ability with metal ions, which can be used to design active sites directionally, thereby precisely regulating the state and quantity of active centers. Summary of the Invention

[0005] The purpose of the present invention is to provide a copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst, its preparation method and application, and this catalyst can achieve efficient photocatalytic CO2 reduction through the synergistic effect of near-infrared region expansion and surface interface polarization.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] The present invention provides a copper porphyrin modified BiOBr / Bi 19 S27 Br3 catalyst, with BiOBr / Bi 19 S 27 Br3 as the carrier and CuTCPP as the photocatalytic active component, which is uniformly dispersed on the surface of the carrier. Based on 100 mg of the carrier, the loading amount of CuTCPP is 0.5 - 1.5 mg.

[0008] Preferably, BiOBr / Bi 19 S 27 Br3 is prepared by the following steps: Add Bi(NO3), KBr, thiourea and polyvinylpyridone into a mannitol solution, stir strongly at room temperature for 60 min, then carry out a hydrothermal reaction at 180 - 200 °C for 20 - 30 h, wash and then dry.

[0009] Specifically, the concentration of the mannitol solution is 0.1 M.

[0010] Specifically, the molar ratio of Bi(NO3), KBr, and thiourea is 5:5:4.5.

[0011] Specifically, carry out the hydrothermal reaction at 180 °C for 20 h.

[0012] Copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst preparation method, including the following steps: Add BiOBr / Bi 19 S 27 Br3 into an N,N-dimethylformamide solution, stir vigorously at room temperature for 20 min, then add CuTCPP, continue to stir for 20 min, and then react at 90 °C for 5 h to obtain the copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst.

[0013] The present invention also provides the application of the above copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst in photocatalytic CO2 reduction.

[0014] Preferably, the application includes the following steps:

[0015] Disperse the catalyst in deionized water and place it in a reactor. After reaching adsorption equilibrium under dark reaction conditions, carry out a photocatalytic reaction to complete the process of photocatalytic CO2 reduction.

[0016] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0017] (1) A copper porphyrin modified BiOBr / Bi provided by the present invention 19 S27 The Br3 catalyst, by introducing Bi into BiOBr 19 S 27 The Br3 photocatalyst, the light response of this composite catalyst is extended to the near-infrared (NIR) region, enhancing the utilization efficiency of the photocatalyst for sunlight.

[0018] (2) A copper porphyrin modified BiOBr / Bi provided by the present invention 19 S 27 The Br3 catalyst, the strong coupling interface enhances carrier polarization, and the photo-generated electrons are directionally transferred and aggregated on the Cu atoms.

[0019] (3) A copper porphyrin modified BiOBr / Bi provided by the present invention 19 S 27 The Br3 catalyst, CuTCPP provides a large number of active Cu sites in the composite catalyst, enhancing CO2 photoreduction.

[0020] (4) A copper porphyrin modified BiOBr / Bi provided by the present invention 19 S 27 The Br3 catalyst, the built-in electrons formed at the interface induce the acceleration transfer of electrons from BiOBr / Bi 19 S 27 to the conduction band of Br3 in CuTCPP, inhibiting the accelerated recombination of electrons and holes.

[0021] (5) The application of a copper porphyrin modified BiOBr / Bi 19 S 27 The Br3 catalyst in photocatalytic CO2 reduction, its application operation requirements are not high, the reaction conditions are mild, environmentally friendly, and meet the requirements of industrial production. After the photocatalytic CO2 reduction process is completed, the catalyst can be separated from the reaction solution by centrifugation, and the stability of the composite catalyst is good. The present invention provides a new way for green and efficient heterojunction catalysts. Description of the Drawings

[0022] Figure 1 TEM photograph of BBS prepared in Example 1;

[0023] Figure 2 TEM photograph of the BBS-CT-2 catalyst prepared in Example 3;

[0024] Figure 3 HRTEM image of the BBS-CT-2 catalyst prepared in Example 3;

[0025] Figure 4XRD patterns of BBS, CuTCPP and composites with different loadings (BBS-CT-1, BBS-CT-2 and BBS-CT-3) prepared in Examples 1-5 and BBS-CA catalyst prepared in Comparative Example 1;

[0026] Figure 5 FTIR spectra of BBS, CuTCPP and BBS-CT-2 prepared in Examples 1-3;

[0027] Figure 6 Raman spectra of BBS, BBS-CT-2 and BBS-CA prepared in Examples 1, 3 and Comparative Sample 1;

[0028] Figure 7 XPS full spectrum of BBS-CT-2 prepared in Example 3;

[0029] Figure 8 Bi 4f spectra of BBS, BBS-CT-2 and BBS-CA prepared in Examples 1, 3 and Comparative Sample 1;

[0030] Figure 9 Br 3d spectra of BBS, BBS-CT-2 and BBS-CA prepared in Examples 1, 3 and Comparative Sample 1;

[0031] Figure 10 S2p spectra of BBS, BBS-CT-2 and BBS-CA prepared in Examples 1, 3 and Comparative Sample 1;

[0032] Figure 11 Cu 2p spectrum of BBS-CT-2 prepared in Example 3;

[0033] Figure 12 Photocatalytic activity diagrams of BBS, CuTCPP and composites with different loadings (BBS-CT-1, BBS-CT-2 and BBS-CT-3) prepared in Examples 1-5 and BBS-CA catalyst prepared in Comparative Example 1;

[0034] Figure 13 Stability test of photocatalysis for 20 h of BBS-CT-2 prepared in Example 3; Detailed Description of the Invention

[0035] The present invention will be described in detail below with reference to specific examples. The embodiments of the present invention are not limited to the scope described in the examples.

[0036] The inventors initially intended to prepare Bi 19 S 27Br3 catalyst, but in the preparation process, BiOBr / Bi was successfully synthesized by a one-step hydrothermal method 19 S 27 Br3 heterojunction composite catalyst, and then its photocatalytic performance was tested. It was found that the photocatalytic CO2 performance was excellent. On this basis, the inventor used the BiOBr / Bi 19 S 27 Br3 heterojunction composite catalyst as a carrier and CuTCPP as a photocatalytic active component, and uniformly dispersed it on the surface of the carrier to obtain the copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst.

[0037] Example 1:

[0038] Weigh 5 mmol Bi(NO3), 5 mmol KBr, 4.5 mmol thiourea and 1 g polyvinylpyridone and add them to 60 mL mannitol solution (0.1 M). Stir vigorously at room temperature for 60 min, then transfer to a 100 mL reaction kettle, heat at 180 °C for 20 h, wash with deionized water and ethanol alternately to remove impurities, and place in a blast drying oven to dry at 60 °C for 6 h, marked as BBS.

[0039] Example 2:

[0040] Dissolve CuCl2·2H2O (37.5 μmol, 6.4 mg) and TCPP (12.5 μmol, 9.9 mg) in a mixed solution of DMF (15 mL) and n-hexane (5 mL). After stirring vigorously on a magnetic stirrer for 15 min, add PVP (5 mg) and CF3COOH (20 μL) and continue to stir for 10 min. Finally, transfer the mixture to a round-bottom flask and heat and stir at 80 °C for 2 h. After the reaction is completed, centrifuge the final product and wash it repeatedly with DMF, ethanol and water to obtain CuTCPP.

[0041] Example 3:

[0042] Weigh 0.1 g of BBS prepared in Example 1 and add it to 30 mL of N,N-dimethylformamide solution. Stir vigorously at room temperature for 20 min, then add 1 mg of CuTCPP respectively and continue to stir for 20 min. Then react at 90 °C in a round-bottom flask for 5 h. The prepared substances are named BBS-CT-2 respectively.

[0043] Example 4:

[0044] According to the method of Example 3, copper porphyrin modified BiOBr / Bi 19 S 27Br3 catalyst, except that the addition amount of CuTCPP is 0.5 mg, and the catalyst is named BBS-CT-1.

[0045] Example 5:

[0046] Modify BiOBr / Bi with copper porphyrin according to the method of Example 3 19 S 27 Br3 catalyst, except that the addition amount of CuTCPP is 1.5 mg, and the catalyst is named BBS-CT-3.

[0047] Comparative Example 1:

[0048] Prepare BBS catalyst loaded with copper acetate according to the method of Example 3, except that copper porphyrin is replaced with copper acetate to obtain BBS-CA catalyst.

[0049] Figure 1 It is the TEM photo of BBS prepared in Example 1. BBS consists of a typical BiOBr two-dimensional sheet structure and a typical Bi 19 S 27 Br3 rod-like structure, and the thickness of the nanosheet is about 3 nm.

[0050] Figure 2 It is the TEM photo of BBS-CT-2 prepared in Example 2. The morphology of BBS-CT-2 is similar to that of BBS, but no obvious CuTCPP morphology is found in BBS-CT-2, which may be due to the small addition amount.

[0051] Figure 3 It is the HRTEM image of the BBS-CT-2 catalyst prepared in Example 3. The lattice spacings detected by the HRTEM image are 0.284 nm and 0.204 nm respectively, corresponding to the (022) plane of BiOBr and Bi 19 S 27 Br3's (321) plane. The results show that BiOBr and Bi in BBS-CT-2 19 S 27 Br3 exist in a heterojunction structure.

[0052] Figure 4 It is the XRD pattern of BBS, CuTCPP and composite materials with different loading amounts (BBS-CT-1, BBS-CT-2 and BBS-CT-3) prepared in Examples 1-5 and the BBS-CA catalyst prepared in Comparative Example 1. The XRD results show that the BBS synthesized by the solvothermal method has both the characteristic peaks of BiOBr and Bi 19 S 27The characteristic peak of Br3 indicates the successful preparation of the composite material. Since the doping of CuTCPP does not destroy the BBS crystal structure, the height of the BBS characteristic peak is similar to that of the BBS-CT peak.

[0053] Figure 5 FTIR spectra of BBS, CuTCPP, and BBS-CT-2 prepared in Examples 1 to 3. The characteristic peak observed near 1000 cm -1 of CuTCPP is the stretching vibration of Cu-N. It can be seen in BBS-CT-2 that there is an obvious characteristic peak at a wavelength of 1000 cm -1 , indicating that CuTCPP has been successfully introduced into BBS.

[0054] Figure 6 Raman spectra of BBS, BBS-CT-2, and BBS-CA prepared in Example 1, 3, and Comparative Sample 1. The chemical structures of the prepared materials were characterized by Raman. It can be inferred that the three different characteristic peaks located at 115, 145, and 266 cm -1 are related to Bi-Br / S substances. Compared with BBS, due to the interaction between BBS and CuTCPP, the characteristic peaks of BBS-CT-2 show a blue shift.

[0055] Figure 7 XPS full spectrum of BBS-CT-2 prepared in Example 3. It can be seen from the full spectrum that BBS-CT-2 is composed of 7 chemical elements, indicating the successful preparation of the composite material. This conclusion is consistent with the FTIR results, proving the successful loading of CuTCPP in BBS.

[0056] Figure 8 Bi 4f spectra of BBS, BBS-CT-2, and BBS-CA prepared in Example 1, 3, and Comparative Sample 1. The Bi 4f spectrum of BBS has two characteristic peaks at 158.36 and 163.66 eV, belonging to 4f 7 / 2 and 4f 5 / 2 of Bi 4f, respectively. Compared with BBS, the peaks of BBS-CT-2 show a red shift, confirming the existence of charge transfer at the interface between BBS and CuTCPP. The characteristic peaks of BBS-CA and BBS are the same, with no obvious change.

[0057] Figure 9 Br 3d spectra of BBS, BBS-CT-2, and BBS-CA prepared in Example 1, 3, and Comparative Sample 1. The characteristic peaks of 67.33 and 68.43 eV that appear in the Br 3d spectrum of BBS correspond to 3d 1 / 2 and 3d 3 / 2 , respectively.

[0058] Figure 10 S2p spectra of BBS, BBS-CT-2, and BBS-CA prepared in Examples 1, 3, and Comparative Sample 1. BBS in S2p has two characteristic peaks at 158.37 and 163.70 eV, belonging to S2p 3 / 2 and S2p 1 / 2 . In addition, the characteristic peaks of BBS-CT-2 in S2p and Br 3d shift towards higher binding energies. As is well known, an increase in binding energy indicates a decrease in external electron density, suggesting a decrease in the electron density of Bi 4f, S2p, and Br 3d. This conclusion indicates that electrons flow out of BBS.

[0059] Figure 11 Cu 2p spectrum of BBS-CT-2 prepared in Example 3. Cu 2p 3 / 2 and Cu 2p 1 / 2 are located near 934.55 eV and 951.88 eV respectively, further proving that CuTCPP has been successfully introduced into BBS.

[0060] Figure 12 Photocatalytic activity diagrams of BBS, CuTCPP, and composite materials with different loadings (BBS-CT-1, BBS-CT-2, and BBS-CT-3) prepared in Examples 1-5 and the BBS-CA catalyst prepared in Comparative Example 1. Under the full spectrum of a 300W xenon lamp, photocatalytic CO2 reduction experiments were carried out in pure water medium. BBS-CT-2 has high photocatalytic performance, which is not only 3.5 times that of BBS but also 1.8 times that of BBS-CA within 5h.

[0061] Figure 13 A 20h stability test was carried out on the photocatalysis of BBS-CT-2 prepared in Example 3. The main experimental steps were as follows: After washing the catalyst after the above photocatalytic reaction with absolute ethanol, it was dried at 80°C for 6h to obtain the photocatalyst for the next cycle, and the photocatalytic experiment was continued. After 3 cycles, the 20h photocatalytic cycle performance was obtained. The results show that through 20h of continuous experiments, the durability and stability of BBS-CT-2 during the photocatalytic process were also confirmed. After 20h of sunlight irradiation, the CO production rate was as high as 207.52 μmol·g -1 . It shows that BBS-CT-2 also exhibits excellent stability and durability in the 20h photocatalytic test.

Claims

1. A copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst, characterized in that Using BiOBr / Bi 19 S 27 Br3 heterojunction as the carrier and CuTCPP as the photocatalytic active component, which is uniformly dispersed on the surface of the carrier. Based on 100 mg of the carrier, the loading amount of CuTCPP is 0.5 - 1.5 mg.

2. The copper porphyrin modified BiOBr / Bi as claimed in claim 1 19 S 27 Br3 catalyst, characterized in that Bi OBr / Bi 19 S 27 The Br3 heterojunction is prepared by the following steps: Add Bi(NO3), KBr, thiourea, and polyvinylpyridone to a mannitol solution, stir vigorously at room temperature for 60 min, then carry out a hydrothermal reaction at 180 - 200 °C for 20 - 30 h, wash and dry.

3. The copper porphyrin-modified BiOBr / Bi 19 S 27 Br3 catalyst according to claim 2, characterized in that The concentration of the mannitol solution is 0.1 M.

4. The copper porphyrin-modified BiOBr / Bi 19 S 27 Br3 catalyst according to claim 2, characterized in that The molar ratio of Bi(NO3), KBr, and thiourea is 5:5:4.

5.

5. The copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst according to claim 2, characterized in that Hydrothermal reaction is carried out at 180 °C for 20 h.

6. The preparation method of the copper porphyrin modified BiOBr / Bi 19 S 27 Br3 catalyst, characterized in that, It includes the following steps: adding the BiOBr / Bi 19 S 27 Br3 heterojunction into an N, N-dimethylformamide solution, vigorously stirring at room temperature for 20 min, then adding CuTCPP, continuing to stir for 20 min, and then reacting at 90 °C for 5 h to obtain the copper porphyrin-modified BiOBr / Bi 19 S 27 Br3 catalyst.

7. The application of the copper porphyrin-modified BiOBr / Bi 19 S 27 Br3 catalyst in photocatalytic CO2 reduction as described in any one of claims 1-5. 19 S 27 Br3 catalyst in photocatalytic CO2 reduction.

8. The application according to claim 7, characterized in that The said application comprises the following steps: dispersing the said catalyst in deionized water and placing it in a reactor, after reaching the adsorption equilibrium under dark reaction conditions, carrying out a photocatalytic reaction to complete the process of photocatalytic CO2 reduction.

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