A rare earth Er single atom and S doped induced BiVO4 phase change heterojunction photocatalytic material and a preparation method and application thereof
By constructing heterojunctions using rare-earth Er single atoms and S-doped BiVO4, the problem of low photogenerated carrier separation efficiency in BiVO4 photocatalytic materials was solved, resulting in improved photocatalytic activity and a significant increase in urea synthesis rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2026-01-29
- Publication Date
- 2026-05-29
AI Technical Summary
The low photogenerated carrier separation efficiency and slow migration rate of BiVO4 photocatalytic materials limit their practical application.
By constructing heterojunctions using rare-earth Er single atoms and S doping, an internal electric field is induced by Er-S to optimize the migration efficiency of photogenerated charges, promote directional electron transport, and enhance the photocatalytic activity of BiVO4.
The photocatalytic activity of BiVO4 was significantly improved, promoting the urea synthesis rate. The efficiency of photocatalytic N2 reduction coupled with methanol oxidation to synthesize urea reached 136.78 μmol/g/h, which is 4.88 times and 3.02 times that of ZnCdS and BiVO4, respectively.
Smart Images
Figure CN122098613A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalytic materials technology, and relates to a heterojunction photocatalytic material with rare earth Er single atom and S doping-induced BiVO4 phase transition, its preparation method and application. Background Technology
[0002] Solar energy is a renewable energy source with virtually no limitations. It can be directly developed and utilized, is easy to collect without the need for specialized mining and transportation, and is one of the cleanest energy sources. Therefore, the utilization of solar energy has received widespread attention.
[0003] Converting solar energy into chemical energy is one of the ways to utilize solar energy on a large scale. Photocatalytic materials are typical conversion materials for this purpose, and the separation of photogenerated charges is crucial for advancing the design and efficiency improvement of solar energy conversion materials. Therefore, technologies that improve the separation efficiency of photogenerated charges in the bulk and surface phases of photocatalytic materials are essential.
[0004] Among numerous photocatalytic materials, bismuth-based catalysts possess a unique layered structure, consisting of [Bi₂O₂] layers interspersed with interlayer ions or functional groups, exhibiting both enrichment and low toxicity. BiVO₄ has been extensively studied due to its suitable wide bandgap and excellent visible light response. However, despite the superior light absorption performance of monoclinic BiVO₄, its low photogenerated carrier separation efficiency and slow migration rate severely limit its practical applications.
[0005] Therefore, it is necessary to provide a heterojunction photocatalytic material with rare earth Er single atom and S doping-induced BiVO4 phase transition, as well as its preparation method and application, in order to improve the photocatalytic activity of BiVO4. Summary of the Invention
[0006] To overcome the problems in the prior art, this invention utilizes rare-earth Er single atoms as electron bridges to promote directional electron transport. It constructs a heterojunction through Er-S induction (wherein, the heterojunction is an interface formed between semiconductors with the same chemical composition and similar crystal structure but slightly different energy bands; an internal electric field is formed at the heterojunction interface, serving as the driving force for photogenerated charge separation at the nanoscale, thus improving charge separation and interface dynamics). The heterojunction synergistically optimizes the migration efficiency of photogenerated charges, effectively enhancing the photocatalytic activity of BiVO4. Furthermore, its application in urea synthesis significantly promotes the urea synthesis rate, resulting in a substantial increase in urea production efficiency.
[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention proposes a method for preparing a heterojunction photocatalytic material with rare-earth Er single atom and S doping-induced BiVO4 phase transition, characterized in that the preparation method includes the following steps: (1) Bi(NO3)3·5H2O and NH4VO3 were added sequentially to a dilute nitric acid solution and sonicated until Bi(NO3)3·5H2O and NH4VO3 were completely dissolved. Then Er(NO3)3·5H2O was added and sonicated until Er(NO3)3·5H2O was completely dissolved. At the same time, the pH of the solution was adjusted to neutral. After hydrothermal reaction, the solution was filtered, washed and dried to obtain Er single-atom doped BiVO4 powder (BiVO4-Er).
[0008] In this step, conventional ultrasonic treatment is used to ensure that Bi(NO3)3·5H2O, NH4VO3, and Er(NO3)3·5H2O are completely dissolved in the nitric acid solution.
[0009] The amount of dilute nitric acid solution used is sufficient to completely dissolve Bi(NO3)3·5H2O, NH4VO3, and Er(NO3)3·5H2O; an excess is acceptable.
[0010] (2) The Er single-atom doped BiVO4 powder from step (1) is ultrasonically dispersed in water, and Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S are added sequentially for ultrasonic treatment to completely dissolve Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S. Then, a hydrothermal reaction is carried out. After the hydrothermal reaction, the solid substance is obtained by filtration.
[0011] In this step, BiVO4-Er powder, Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S are completely dissolved in water by conventional ultrasonic treatment.
[0012] The amount of water used should be sufficient to completely dissolve BiVO4-Er powder, Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S; an excess amount is acceptable.
[0013] (3) After calcining, washing, centrifuging and drying the solid material obtained in step (2), a heterojunction photocatalytic material with Er single atom and S doping-induced BiVO4 phase transition is obtained.
[0014] Preferably, in step (1), the molar ratio of Bi(NO3)3·5H2O, NH4VO3 and Er(NO3)3·5H2O is Bi(NO3)3·5H2O:NH4VO3:Er(NO3)3·5H2O=1:1:0.01.
[0015] Preferably, in step (1), the concentration of the dilute nitric acid solution is 2 mol / L.
[0016] Preferably, in step (1), the hydrothermal reaction temperature is 180°C and the reaction time is 6 hours.
[0017] Preferably, in step (2), the molar ratio of Er-doped BiVO4 powder, Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S is Er-doped BiVO4 powder: Cd(NO3)2·4H2O: Zn(NO3)2·6H2O: CH4N2S = 2:0.8:0.2:1.
[0018] Preferably, in step (2), the hydrothermal reaction temperature is 180°C and the reaction time is 4 hours.
[0019] Preferably, in step (3), the calcination temperature is 400℃ and the calcination time is 2h.
[0020] Further optimization involves a heating rate of 5°C / min during the calcination process.
[0021] Preferably, in step (1), ammonia is used to adjust the pH.
[0022] In another aspect, this invention proposes a heterojunction photocatalytic material with rare earth Er single atoms and S doping-induced BiVO4 phase transition prepared by the above preparation method.
[0023] This invention also proposes the application of the above-mentioned photocatalytic material in the photocatalytic N2 reduction coupled with methanol oxidation to synthesize urea.
[0024] The beneficial effects of this invention are: 1. This invention utilizes rare-earth single atoms as electron bridges to accelerate cross-interface transport and promote directional electron transport. Simultaneously, it constructs heterojunctions through Er-S induction, builds built-in electric fields through the heterostructure to promote carrier separation, and optimizes the migration efficiency of photogenerated charges at the interface by leveraging the lattice matching advantage at the heterojunction interface. The two work synergistically to effectively improve the separation efficiency and migration rate of photogenerated carriers in the photocatalytic material, thereby enhancing its photocatalytic activity.
[0025] 2. In the heterojunction photocatalytic material of rare earth Er single atom and S doping induced BiVO4 phase transition of the present invention, the separation effect of photogenerated electrons-holes is effectively improved, so that photogenerated electrons and holes can be used to simultaneously consume N2 reduction and methanol (CH3OH) oxidation, thereby accelerating urea synthesis.
[0026] 3. The photocatalyst of this invention exhibits excellent catalytic performance. When used in the photocatalytic N2 reduction coupled with methanol oxidation to synthesize urea, it can promote the urea synthesis rate to reach 136.78 μmol / g / h, which is 4.88 times and 3.02 times that of ZnCdS and BiVO4, respectively. Attached Figure Description
[0027] Figure 1 The photocatalytic activity diagrams of the photocatalytic materials prepared in Examples 1 and 2 (Comparative Example 8) are shown.
[0028] Figure 2 The XRD patterns of the photocatalytic materials prepared in Examples 3, 4, 6, and 7 are shown. Figure 3 Er 4d XPS diagram of the photocatalytic material prepared for the example.
[0029] Figure 4 The photocatalytic activity diagrams are shown for the photocatalytic materials prepared in Examples 1-7 and Comparative Examples 1-7. Detailed Implementation
[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0031] Example This embodiment prepares rare-earth Er single-atom and S-doped induced BiVO4 heterojunction photocatalytic materials using the following method: (1) Weigh 10 mmol Bi(NO3)3·5H2O and 10 mmol NH4VO3 and add them to 40 mL of 2 mol / L dilute nitric acid solution. After sonication for 30 min, Bi(NO3)3·5H2O and NH4VO3 completely dissolve to obtain a bright yellow solution. Add 0.1 mmol Er(NO3)3·5H2O to the above solution and sonicate for 30 min. Er(NO3)3·5H2O completely dissolves. At the same time, adjust the pH of the solution to neutral using ammonia water. After stirring thoroughly, transfer the solution to a polytetrafluoroethylene reactor and react at 180 °C for 6 h. Filter the reaction product to obtain a precipitate. Wash the precipitate three times with deionized water and dry it at 80 °C for 12 h to obtain BiVO4-Er powder.
[0032] (2) Disperse BiVO4-Er powder in deionized water by ultrasonication, and add Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S in sequence for ultrasonic treatment until BiVO4-Er powder, Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S are completely dissolved, wherein BiVO4-Er:Cd(NO3)2·4H2O:Zn(NO3)2·6H2O:CH4N2S=2:0.8:0.2:1. Transfer the reaction solution to a polytetrafluoroethylene reactor and react at 180℃ for 4h. Filter to obtain solid material.
[0033] (3) The solid material was placed in a muffle furnace and calcined at 400℃ for 2h with a heating rate of 5℃ / min. The calcined product was washed with deionized water, centrifuged, and dried at 80℃ for 12h to obtain a rare earth Er single atom and S doping induced BiVO4 heterojunction photocatalytic material, denoted as 1Er / BVO-ZCS.
[0034] Comparative Example 1 In this comparative example, BiVO4 photocatalytic materials were prepared according to the following method: (1) Weigh 10 mmol Bi(NO3)3·5H2O and 10 mmol NH4VO3 and add them to 40 mL of 2 mol / L dilute nitric acid solution. Sonicate for 30 min to obtain a bright yellow solution. Adjust the pH of the solution to neutral using ammonia water. After stirring thoroughly, transfer the solution to a polytetrafluoroethylene reactor and react at 180 °C for 6 h. Filter the reaction product to obtain a precipitate. Wash the precipitate three times with deionized water and dry it at 80 °C for 12 h to obtain a dry solid.
[0035] (2) The dried solid was placed in a muffle furnace and calcined at 400℃ for 2 hours with a heating rate of 5℃ / min. The calcined product was washed with deionized water, centrifuged, and dried at 80℃ for 12 hours to obtain BiVO4 photocatalytic material, denoted as BVO.
[0036] Comparative Example 2 In this comparative example, Er / BiVO4 photocatalyst material was prepared according to the following method: (1) Weigh 10 mmol Bi(NO3)3·5H2O and 10 mmol NH4VO3 and add them to 40 mL of 2 mol / L dilute nitric acid solution. Sonicate for 30 min to obtain a bright yellow solution. Add 0.1 mmol Er(NO3)3·5H2O to the above solution and sonicate for 30 min. At the same time, adjust the pH of the solution to 7 with ammonia water. After stirring thoroughly, transfer the solution to a polytetrafluoroethylene reactor and react at 180 °C for 6 h. Filter the reaction product to obtain a precipitate. Wash the precipitate three times with deionized water and dry it at 80 °C for 12 h to obtain a dried precipitate.
[0037] (2) The dried precipitate was placed in a muffle furnace and calcined at 400℃ for 2h with a heating rate of 5℃ / min. The calcined product was washed with deionized water, centrifuged, and dried at 80℃ for 12h to obtain Er / BiVO4 photocatalytic material, denoted as 1Er / BVO.
[0038] Comparative Example 3 In this comparative example, BiVO4-ZnCdS photocatalytic material was prepared according to the following method: (1) Weigh 10 mmol Bi(NO3)3·5H2O and 10 mmol NH4VO3 and add them to 40 mL of 2 mol / L dilute nitric acid solution. Stir for 30 min to obtain a bright yellow solution. Adjust the pH of the solution to neutral using ammonia water. After stirring thoroughly, transfer the mixture to a polytetrafluoroethylene reactor. React at 180 °C for 6 h. Filter the reaction product to obtain a precipitate. Wash the precipitate three times with deionized water and dry at 80 °C for 12 h to obtain BiVO4 powder.
[0039] (2) Disperse BiVO4 powder in deionized water by ultrasonication, and add Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S in sequence and stir. The ratio of BiVO4-Er:Cd(NO3)2·4H2O:Zn(NO3)2·6H2O:CH4N2S is 2:0.8:0.2:1. Transfer the reaction solution to a polytetrafluoroethylene reactor and react at 180℃ for 4 hours. Filter to obtain solid material.
[0040] (3) The solid material was placed in a muffle furnace and calcined at 400℃ for 2 hours with a heating rate of 5℃ / min. The calcined product was washed with deionized water, centrifuged, and dried at 80℃ for 12 hours to obtain BiVO4-ZnCdS photocatalytic material, denoted as BVO-ZCS.
[0041] Comparative Example 4 This comparative example prepared ZnCdS photocatalytic materials according to the following method: (1) Weigh out Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S according to the molar ratio of Cd(NO3)2·4H2O:Zn(NO3)2·6H2O:CH4N2S=0.8:0.2:1 and add them to 80mL of deionized water. Stir for 30min and then perform hydrothermal reaction at 180℃ for 4h. Filter the reaction product to obtain a precipitate.
[0042] (2) The precipitate was placed in a muffle furnace and calcined at 400℃ for 2h with a heating rate of 5℃ / min. The calcined product was washed with deionized water, centrifuged, and dried at 80℃ for 12h to obtain ZnCdS photocatalyst, denoted as ZCS.
[0043] Comparative Example 5 In this comparative example, BiVO4-ZnCdS-Er photocatalytic materials were prepared according to the following method: (1) Weigh 10 mmol Bi(NO3)3·5H2O and 10 mmol NH4VO3 and add them to 40 mL of 2 mol / L dilute nitric acid solution. Stir for 30 min and adjust the pH of the solution to neutral using ammonia water to obtain a bright yellow solution. After stirring thoroughly, transfer the solution to a polytetrafluoroethylene reactor and react at 180 °C for 6 h. Filter the reaction product to obtain a precipitate. Wash the precipitate three times with deionized water and dry it at 80 °C for 12 h to obtain a powder sample.
[0044] (2) The powder sample was ultrasonically dispersed in deionized water, and Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S were added sequentially and stirred. The molar ratio of Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S was Cd(NO3)2·4H2O:Zn(NO3)2·6H2O:CH4N2S = 0.8:0.2:1. 0.1 mmol Er(NO3)3·5H2O was added to the above solution, and the mixture was stirred for 30 min. After thorough mixing, the solution was transferred to a polytetrafluoroethylene reactor and reacted at 180℃ for 4 h. The solid product was obtained by filtration.
[0045] (3) The solid product was placed in a muffle furnace and calcined at 400℃ for 2h with a heating rate of 5℃ / min. The calcined product was washed with deionized water, centrifuged, and dried at 80℃ for 12h to obtain BiVO4-ZnCdS-Er photocatalytic material, denoted as BVO-ZCS-1Er.
[0046] Comparative Example 6 The photocatalytic material in this comparative example was prepared using the same method as in Example 1, except that the amount of Er(NO3)3·5H2O added was 0.3 mmol, and the photocatalytic material in this comparative example was denoted as 3Er / BVO-ZCS.
[0047] Comparative Example 7 The photocatalytic material in this comparative example was prepared using the same method as in Example 1, except that the amount of Er(NO3)3·5H2O added was 0.5 mmol. The photocatalytic material in this comparative example is denoted as 5Er / BVO-ZCS. Comparative Example 8 The photocatalytic material in this comparative example was prepared using the same method as in Example 1, except that the hydrothermal reaction temperature in steps (1) and (2) was 160°C.
[0048] Experimental tests were conducted on the materials obtained in Comparative Example 1 and Comparative Example 8, such as... Figure 1 As shown.
[0049] pass Figure 1 It can be seen that, under visible light irradiation, the performance of the photocatalytic material in Comparative Example 8 is far lower than that of the photocatalytic material in Example 1.
[0050] Example of effect The materials prepared in Examples 1-7 and Comparative Examples 1-7 were subjected to relevant performance tests, and the results are as follows: pass Figure 2 It can be seen that the peak marked with a black heart shape is consistent with the characteristic diffraction peak of ZCS. The peak marked with a red quadrilateral is consistent with the characteristic diffraction peak of BVO, pointing to the monoclinic phase BVO (JCPDS No. 14-0688), and the peak marked with a magenta plum blossom is consistent with the characteristic diffraction peak of the tetragonal phase BVO (JCPDS No. 14-0133). With the increase of Er content, BVO gradually transforms from the monoclinic phase to the tetragonal phase. In addition, when the Er content is 1% and 3%, the tetragonal and monoclinic phases of BVO coexist. However, the tetragonal phase accounts for a smaller proportion in the sample with 1% Er content, while the tetragonal phase accounts for a larger proportion in the sample with 3% Er content. In the sample with 5% Er content, BVO completely transforms from the monoclinic phase to the tetragonal phase. Based on these results, it is judged that Er may induce lattice distortion in BVO, making its lattice unstable. After the addition of ZCS, the S-Er-O bond coordination induces a phase transition, promoting the stable existence of the metastable phase of BVO.
[0051] pass Figure 3 It can be seen that the peak of Er 4d is located between 168.7 eV and 169.2 eV, proving that Er does not exist in the form of ions, but in the form of a special coordinated single atom in the support.
[0052] The photocatalytic performance of the prepared catalyst was evaluated by its activity in the urea production reaction coupled with N2 and CH3OH. Figure 4 It can be seen that the urea yield is very low when using BVO and ZCS. Introducing Er-S to induce the construction of a heterojunction (1Er / BVO-ZCS) can significantly improve its activity, further increasing the yield of urea synthesized by photocatalytic coupling of N2 and CH3OH. Under visible light irradiation, 1Er / BVO-ZCS exhibits excellent urea synthesis performance, with a synthesis rate of 136.78 μmol / g / h, which is 4.88 times (28.01 μmol / g / h) and 3.02 times (45.21 μmol / g / h) of ZCS and BVO, respectively.
[0053] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.
Claims
1. A method for preparing a heterojunction photocatalytic material with rare earth Er single atom and S doping-induced BiVO4 phase transition, characterized in that: The preparation method includes the following steps: (1) Bi(NO3)3·5H2O and NH4VO3 were added sequentially to a dilute nitric acid solution and sonicated until Bi(NO3)3·5H2O and NH4VO3 were completely dissolved. Then Er(NO3)3·5H2O was added and sonicated until Er(NO3)3·5H2O was completely dissolved. At the same time, the pH of the solution was adjusted to neutral. After hydrothermal reaction, the solution was filtered, washed and dried to obtain Er single-atom doped BiVO4 powder. (2) The Er single-atom doped BiVO4 powder from step (1) is ultrasonically dispersed in water, and Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S are added sequentially for ultrasonic treatment to completely dissolve Cd(NO3)2·4H2O, Zn(NO3)2·6H2O and CH4N2S. Then, a hydrothermal reaction is carried out. After the hydrothermal reaction, the solid substance is obtained by filtration. (3) After calcining, washing, centrifuging and drying the solid material obtained in step (2), a heterojunction photocatalytic material with Er single atom and S doping-induced BiVO4 phase transition is obtained.
2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of Bi(NO3)3·5H2O, NH4VO3 and Er(NO3)3·5H2O is Bi(NO3)3·5H2O:NH4VO3:Er(NO3)3·5H2O=1:1:0.
01.
3. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the dilute nitric acid solution is 2 mol / L.
4. The preparation method according to claim 1, characterized in that: In step (1), the hydrothermal reaction temperature is 180℃ and the reaction time is 6h.
5. The preparation method according to claim 1, characterized in that: In step (2), the molar ratio of Er single-atom doped BiVO4 powder, Cd(NO3)2·4H2O, Zn(NO3)2·6H2O, and CH4N2S is Er single-atom doped BiVO4 powder: Cd(NO3)2·4H2O: Zn(NO3)2·6H2O: CH4N2S = 2:0.8:0.2:
1.
6. The preparation method according to claim 1, characterized in that: In step (2), the hydrothermal reaction temperature is 180℃ and the reaction time is 4h.
7. The preparation method according to claim 1, characterized in that: In step (3), the calcination temperature is 400℃ and the calcination time is 2h.
8. The preparation method according to claim 1, characterized in that: In step (1), ammonia is used to adjust the pH.
9. The heterojunction photocatalytic material with rare earth Er single atom and S doping-induced BiVO4 phase transition prepared by the preparation method according to any one of claims 1-8.
10. The application of the heterojunction photocatalytic material of claim 9, which is a rare earth Er single atom and S doping-induced BiVO4 phase transition, in the photocatalytic N2 reduction coupled with methanol oxidation to synthesize urea.