Preparation method of silver monatomic anchoring oxygen-rich defect bromine tri-bismuth oxide nanosheet photocatalyst and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EAST CHINA UNIV OF SCI & TECH
- Filing Date
- 2026-04-16
- Publication Date
- 2026-06-30
Smart Images
Figure CN122298457A_ABST
Abstract
Description
Technical Field
[0001] This invention provides a method for preparing a silver single-atom anchored oxygen-rich defect bismuth tetroxide nanosheet photocatalyst (AgSAs-Bi3O4Br, AgSAs-BOB) and its application. Background Technology
[0002] Currently, with the massive combustion of fossil fuels, greenhouse gases, primarily carbon dioxide (CO2), are being emitted in large quantities, causing global temperatures to rise continuously. The development of CO2 conversion and utilization technologies is urgently needed. Photocatalytic CO2 reduction (PCRR) technology utilizes visible sunlight to reduce CO2 into compounds with high economic value. This technology greatly contributes to achieving the dual-carbon goal. It is an ideal technology for carbon conversion. Although PCRR technology has been extensively studied, simple semiconductor catalysts still suffer from low conversion rates and low selectivity.
[0003] Bismuth oxybromide (BiOBr) is a typical layered semiconductor with the properties [Bi₂O₂]. 2+ Layers and Br - The alternating stacked two-dimensional layered structure of BiOBr exhibits strong internal electric field and anisotropy, which is beneficial for carrier separation and directional transport. A suitable band gap allows the material to respond to natural visible light, and through surface modification and doping, the band structure can be tuned to further enhance its catalytic effect under visible light.
[0004] Single-atom catalysts possess high atom utilization and excellent catalytic performance, capable of altering the adsorption and desorption of different molecules by the active components on the catalyst, as well as the electronic structure of the active sites. Single atoms provide ample reaction sites during the reaction process, promoting the migration of reaction intermediates and greatly optimizing the adsorption, activation, and reduction processes of CO2. Previous studies have reported that introducing single-atom catalysts such as silver, copper, and gold onto semiconductor materials is a highly efficient catalyst modification method, which can significantly improve the yield and selectivity of the products.
[0005] Therefore, this study provides a method for preparing a silver single-atom-anchored photocatalyst of oxygen-rich defective bismuth tetroxide (BTO) nanosheets. Using ethylene glycol (EG) as a solvent and silver nitrate as the silver source, AgSAs-BOB nanosheets were synthesized via a one-step hydrothermal method. The nanosheet morphology of BOB significantly increases the specific surface area of the catalyst and reduces the migration distance of photogenerated electrons within the catalyst. Simultaneously, the anchoring of silver single atoms provides more reactive sites, achieving a substantial improvement in photocatalytic CO2 reduction performance with a relatively low silver content. Experimental verification shows that the synergistic effect of silver single atoms and oxygen vacancies promotes CO2 activation, lowers the energy barrier of key steps in subsequent PCRR, and effectively improves the yield and selectivity of CH4. Summary of the Invention
[0006] This invention provides a method for preparing a silver single-atom anchored oxygen-rich defect bismuth tetroxide nanosheet photocatalyst. Using bismuth nitrate pentahydrate as a precursor, hexadecyltrimethylammonium bromide is used to replace part of polyvinylpyrrolidone as a surfactant, and ethylene glycol is used as a solvent. AgNO3 is added to the solution, and AgSAs-BOB is synthesized via a one-step hydrothermal method. A series of characterization methods confirmed the successful preparation of this composite material, which exhibits excellent photocatalytic carbon dioxide reduction ability. This is because the BOB nanosheet structure and the incorporation of silver single atoms provide a higher specific surface area. The oxygen vacancies in BOB synergistically interact with AgSAs, providing multiple active sites for the reaction and improving the yield and selectivity of the CH4 product. Under the optimal silver loading of 1%, the CO2 reduction performance of this catalyst is significantly improved, with a CH4 yield as high as 37.6 μmol g in a 4-h test. −1 h −1 The CO yield was 7.35 μmol g. −1 h −1 The overall CO2 product selectivity is over 90%. This catalyst maintains good high efficiency and stability during a 16-hour long-term test.
[0007] A method for preparing a silver single-atom anchored oxygen-rich defect bismuth tetroxide nanosheet photocatalyst, characterized by comprising the following steps:
[0008] 1) Dissolve bismuth nitrate pentahydrate in ethylene glycol and label it as solution A.
[0009] 2) Dissolve hexadecyltrimethylammonium bromide and polyvinylpyrrolidone in ethylene glycol and label it as solution B;
[0010] 3) Sonicate solutions A and B for 5 minutes each to ensure uniform dispersion.
[0011] 4) Slowly add solution A to B, and add AgNO3 to adjust the pH to 11.5.
[0012] 5) Transfer the mixed solution to a stainless steel high-pressure reactor and keep it at 160 °C for 12 h. Finally, wash the obtained precipitate with deionized water and ethanol alternately six times, collect the solid precipitate after centrifugation, dry it, and obtain AgSAs-BOB nanosheets.
[0013] Furthermore, in Ag SAs-BOB nanosheets, the loading of silver single atoms is 0.5-3 wt%, with BOB nanosheets as 100%.
[0014] Furthermore, in step 1, 3184.88 mg of bismuth nitrate pentahydrate was weighed and dissolved in 25 mL of ethylene glycol.
[0015] Furthermore, in step 2, 1457.80 mg of cetyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were weighed and dissolved in 25 mL of ethylene glycol.
[0016] Furthermore, in step 4, the added AgNO3 is 14.70 mg to 88.20 mg depending on the loading amount.
[0017] Furthermore, in step 4, the pH of the solution is adjusted to 11.5 using 2 mol / L NaOH.
[0018] Furthermore, in step 5, the stainless steel high-pressure reactor is lined with Teflon, and the hydrothermal reactor is kept at 160 °C for 12 h.
[0019] Furthermore, in step 5, the solid precipitate is dried in a vacuum oven at 60 °C for more than 12 h.
[0020] The beneficial effects of the present invention
[0021] 1) This invention significantly improves the internal electron distribution of the material by anchoring silver in the form of single atoms within the BOB nanosheet structure, forming stable local charge regulation centers in the crystal lattice. Silver single atoms have higher atomic utilization efficiency and can serve as effective electron trapping sites, accelerating the migration of photogenerated electrons from the BOB host to surface active sites, significantly suppressing electron-hole recombination, thereby improving the separation efficiency of photogenerated carriers and the overall photocatalytic reaction activity.
[0022] 2) The Ag SAs-BOB nanosheets obtained in this invention have a higher density and more uniformly distributed surface active sites, which can significantly enhance the adsorption and activation capabilities of reactant molecules. The silver single atom forms a special coordination environment with the surrounding Bi, O, and Br atoms, which is beneficial for inducing the formation of charge-rich regions on the surface, improving the adsorption capacity for linear inert molecules such as CO2, and reducing the reaction energy barrier in the formation of key intermediate products, thereby improving the catalytic reaction rate and product selectivity.
[0023] 3) The synergistic effect of oxygen vacancies and Ag SAs provides multiple reactive sites for the PCRR system. Oxygen vacancies effectively regulate the band structure of the material, enhancing its absorption capacity in the visible light region. This promotes CO2 adsorption and activation; silver single atoms significantly improve the photocatalytic CO2 reduction performance of BOB under low loading conditions.
[0024] 4) Ag SAs-BOB nanosheets can be synthesized via a simple one-step hydrothermal method, which is low in cost and has a simple process, making it suitable for large-scale industrial production. Attached Figure Description
[0025] Figure 1 (a) Hydrothermal synthesis of x% Ag SAs-BOB (x = 0.5, 1, 2, 3); (b) XRD patterns of 1% Ag SAs-BOB synthesized by photodeposition methods with different light sources.
[0026] Figure 2 (ab) Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of 1% Ag SAs-BOB; (c) Lattice spacing diagram of 1% Ag SAs; (d) HRTEM elemental mapping image of Ag SAs-BOB.
[0027] Figure 3 (ad) High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of 1% Ag SAs-BOB.
[0028] Figure 4 (a) CO of 1% Ag SAs-BOB in-suit DRIFTS spectrum; (b) Raman spectra of 1% Ag NPs-BOB and 1% AgSAs-BOB.
[0029] Figure 5 (ab) Relationship between product yield and CH4 product selectivity of BOB, 1% Ag SAs-BOB and 1% Ag NPs-BOB, and CH4 yield over time; (c) PCR performance of 1% Ag SAs-BOB under different conditions; (de) CH4 and CO yield over time in four cycles of 1% Ag SAs-BOB, and total product and CH4 selectivity; (f) XRD patterns of 1% Ag SAs-BOB and 1% Ag NPs-BOB after reaction.
[0030] Figure 6 XPS spectra of 1% Ag NPs-BOB and 1% Ag SAs-BOB: (a) Ag 3d, (b) Bi 4f, (c) Br 3d, (d) O 1s.
[0031] Figure 7(ab) UV-Vis diffuse reflectance (UV vis-DRS) spectra of BOB, 1% Ag SAs-BOB, and 1% Ag NPs-BOB and Tauc spectra obtained by Kubelka-Munk transformation function; (c) Valence band XPS spectra of Ag SAs-BOB and Ag NPs-BOB; (de) Mott-Schottky diagrams of 1% Ag NPs-BOB and 1% Ag SAs-BOB; (f) Band structure diagrams of BOB, 1% Ag SAs-BOB, and 1% Ag NPs-BOB.
[0032] Figure 8 Electrochemical impedance spectroscopy, photocurrent response spectroscopy, fluorescence emission spectrum, and time-resolved fluorescence decay spectrum of (ad) BOB, 1% Ag SAs-BOB, and 1% Ag NPs-BOB. Detailed Implementation
[0033] Example: Preparation of Ag SAs-BOB nanosheets
[0034] Example
[0035] 3184.88 mg of bismuth nitrate pentahydrate and 14.70 mg of silver nitrate were dissolved in 25 mL of ethylene glycol and labeled A. Simultaneously, 1457.80 mg of hexadecyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were dissolved in 25 mL of ethylene glycol and labeled B. Both solutions were sonicated for 5 min to ensure uniform dispersion. Solution A was then slowly added dropwise to solution B while stirring uniformly for 30 min. Finally, the pH was adjusted to 11.5 using 2 M NaOH solution. The mixed solution was then transferred to a 100 mL Teflon-lined stainless steel autoclave and incubated at 160 °C for 12 h. The resulting precipitate was washed six times alternately with deionized water and ethanol. After centrifugation, the solid precipitate was collected and vacuum dried at 60 °C for more than 12 h to obtain 0.5% silver single-atom anchored bismuth tetroxide ultrathin nanosheets, labeled 0.5% Ag SAs-BOB.
[0036] Example
[0037] 3184.88 mg of bismuth nitrate pentahydrate and 29.40 mg of silver nitrate were dissolved in 25 mL of ethylene glycol and labeled A. Simultaneously, 1457.80 mg of hexadecyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were dissolved in 25 mL of ethylene glycol and labeled B. Both solutions were sonicated for 5 min to ensure uniform dispersion. Solution A was then slowly added dropwise to solution B while stirring uniformly for 30 min. Finally, the pH was adjusted to 11.5 using 2 M NaOH solution. The mixed solution was then transferred to a 100 mL Teflon-lined stainless steel autoclave and incubated at 160 °C for 12 h. The resulting precipitate was washed six times alternately with deionized water and ethanol. After centrifugation, the solid precipitate was collected and vacuum dried at 60 °C for over 12 h to obtain 1% silver single-atom anchored bismuth tetroxide ultrathin nanosheets, labeled 1% Ag SAs-BOB.
[0038] Example
[0039] 3184.88 mg of bismuth nitrate pentahydrate and 58.80 mg of silver nitrate were dissolved in 25 mL of ethylene glycol and labeled A. Simultaneously, 1457.80 mg of hexadecyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were dissolved in 25 mL of ethylene glycol and labeled B. Both solutions were sonicated for 5 min to ensure uniform dispersion. Solution A was then slowly added dropwise to solution B while stirring uniformly for 30 min. Finally, the pH was adjusted to 11.5 using 2 M NaOH solution. The mixed solution was then transferred to a 100 mL Teflon-lined stainless steel autoclave and incubated at 160 °C for 12 h. The resulting precipitate was washed six times alternately with deionized water and ethanol. After centrifugation, the solid precipitate was collected and vacuum dried at 60 °C for more than 12 h to obtain 2% silver single-atom anchored bismuth tetroxide ultrathin nanosheets, labeled 2% Ag SAs-BOB.
[0040] Example
[0041] 3184.88 mg of bismuth nitrate pentahydrate and 88.20 mg of silver nitrate were dissolved in 25 mL of ethylene glycol and labeled A. Simultaneously, 1457.80 mg of hexadecyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were dissolved in 25 mL of ethylene glycol and labeled B. Both solutions were sonicated for 5 min to ensure uniform dispersion. Solution A was then slowly added dropwise to solution B while stirring uniformly for 30 min. Finally, the pH was adjusted to 11.5 using 2 M NaOH solution. The mixed solution was then transferred to a 100 mL Teflon-lined stainless steel autoclave and incubated at 160 °C for 12 h. The resulting precipitate was washed six times alternately with deionized water and ethanol. After centrifugation, the solid precipitate was collected and vacuum dried at 60 °C for more than 12 h to obtain 3% silver single-atom anchored bismuth tetroxide ultrathin nanosheets, labeled 3% Ag SAs-BOB.
[0042] Comparative Example 1
[0043] Preparation of BOB nanosheets
[0044] 3184.88 mg of bismuth nitrate pentahydrate was dissolved in 25 mL of ethylene glycol and labeled A. Simultaneously, 1457.80 mg of hexadecyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were dissolved in 25 mL of ethylene glycol and labeled B. Both solutions were sonicated for 5 min to ensure uniform dispersion. Solution A was then slowly added dropwise to solution B while stirring uniformly for 30 min. Finally, the pH was adjusted to 11.5 using 2 M NaOH solution. The mixed solution was then transferred to a 100 mL Teflon-lined stainless steel autoclave and incubated at 160 °C for 12 h. The resulting precipitate was washed six times alternately with deionized water and ethanol. After centrifugation, the solid precipitate was collected and vacuum dried at 60 °C for more than 12 h to obtain bismuth tetroxide nanosheets, labeled BOB.
[0045] Comparative Example 2
[0046] 1% Ag NPs-BOB (Silver Nanoparticle Loading)
[0047] Photochemical deposition was used to synthesize the silver nanoparticle catalyst. First, 100 mg BOB and 1.58 mg AgNO3 were dispersed in 100 mL of ethanol and ultrasonically dispersed until homogeneous. The suspension was then placed in a sealed stainless steel container. Before irradiation, the system was continuously evacuated for 5 min to ensure complete removal of air, and then argon gas at 0.2 MPa was introduced. Then, the samples were irradiated at 25 °C for 1 h using a 300 W xenon lamp and an LED lamp, respectively, to obtain silver nanoparticle samples synthesized under different light source conditions. Finally, the precipitate was washed three times with deionized water, the solid precipitate was collected by centrifugation, and then vacuum dried at 60 °C for more than 12 h.
[0048] Experiments and data
[0049] The method for evaluating the photocatalytic reduction of CO2 provided by this invention is as follows.
[0050] Weigh 20 mg of catalyst into a 2 ml centrifuge tube, shake and sonicate to disperse in 1 mL of deionized water. Place a glass fiber filter membrane in a glass petri dish, uniformly disperse it on the surface, and then transfer it to a 60 ℃ forced-air drying oven for drying. After drying, place the corresponding glass petri dish on a support in a 300 mL sealed glass reactor, set the circulating water temperature to 40 ℃, and pump 2 mL of ultrapure water under the support. Evacuate the entire system to a vacuum, introduce approximately 0.1 MPa of CO2, turn on the plunger pump, and allow CO2 to circulate throughout the system for 5-10 min. Then evacuate again, circulate twice, and finally inject 90 kPa of CO2 as the reaction gas. After allowing CO2 to adsorb on the catalyst surface for 30 min, turn on a 300 W xenon lamp to irradiate and start the reaction. Gas chromatography automatically injects samples every 30 min to analyze the gaseous products. The performance of the examples and comparative examples in the 4 h test is shown in the table below.
[0051] Table 1 shows the performance of the examples and comparative examples in the 4h photocatalytic CO2 reduction experiment.
[0052] Sample Name <![CDATA[CH4 production (μmol·g -1 h -1 ).]]> <![CDATA[CO production (μmol·g -1 h -1 ).]]> <![CDATA[CH4 Electroselectivity]]> Example 1 (0.5% Ag SAs-BOB) 27.1 1.67 98.5% Example 2 (1% Ag SAs-BOB) 37.6 7.35 95.3% Example 3 (2% Ag SAs-BOB) 11.2 1.01 97.8% Example 4 (3% Ag SAs-BOB) 9.03 0.594 98.4% Comparative Example 1 (BOB) 3.8 0.379 97.6% Comparative Example 2 (1% Ag NPs-BOB) 12.8 19.2 72.7%
[0053] Figure 1XRD patterns of 0.5% Ag SAs-BOB, 1% Ag SAs-BOB, 2% Ag SAs-BOB and 3% Ag SAs-BOB are shown. The main XRD characteristic peaks at 23.9°, 29.2°, 31.6°, 42.6°, 45.1°, 50.2°, 53.4°, 54.9° and 56.5° are attributed to the (112), (114), (020), (206), (220), (033), (110), (314) and (315) crystal planes of the Bi3O4Br standard card. No Ag-related XRD diffraction peaks were observed in the x% Ag SAs-BOB sample, which is partly due to the low Ag loading and partly due to the high dispersion of silver single atoms. After the introduction of Ag, the characteristic diffraction peaks of all samples were consistent with those of BOB, indicating that the substrate material had not changed. However, the characteristic peaks of BOB shifted slightly, indicating that silver single atoms were successfully anchored into the BOB lattice.
[0054] Figure 2 The images show TEM, HRTEM, and elemental mapping images of 1%Ag SAs-BOB. At a 50 nm scale, the sheet-like structure of 1%Ag SAs-BOB is clearly visible. At a 10 nm scale, a clear lattice spacing of 0.285 nm is observed, belonging to the (200) crystal plane of Bi3O4Br. No obvious nanoparticles or nanoclusters were observed, indicating that silver single atoms were successfully introduced into Bi3O4Br, and that the four elements Bi, O, Br, and Ag are uniformly distributed on the catalyst surface, with shapes consistent with the TEM images of 1%Ag SAs-BOB.
[0055] Figure 3 The image shows a HAADF-STEM image of 1%Ag SAs-BOB. The surface of 1%Ag SAs-BOB exhibits a uniform atomic arrangement, with no obvious silver nanoparticles detected. Both Ag and Bi atoms are heavy atoms, making it impossible to observe single Ag atoms based on obvious atomic dark spots. In contrast, the (311) crystal plane of Bi3O4Br has a lattice spacing of 0.354 nm. The anchoring of silver atoms causes lattice distortion, reducing the lattice spacing to 0.352 nm. Therefore, this study determined the presence of single silver atoms based on the lattice distortion caused by the anchoring of metal atoms due to differences in atomic radius.
[0056] Figure 4 CO for Ag SAs-BOB in-suit DRIFTS spectra and Raman spectra of Ag NPs-BOB and Ag SAs-BOB. In-situ infrared spectra of Ag SAs-BOB under a CO probe show its activity at 20-25 cm⁻¹. −1The presence of a distinct CO linear adsorption peak at this location further confirms that Ag species in Ag SAs-BOB exist as highly dispersed atoms within the BOB. This is also evident in the Raman spectrum shown in Figure b, at approximately 136 cm⁻¹. −1 The peak value is attributed to the Bi−Br stretching pattern; approximately 136 cm⁻¹ −1 The peak is attributed to the Bi−O bond; approximately 318 cm⁻¹ −1 The peak is attributed to the motion of O atoms; approximately 470 cm⁻¹ −1 The peaks are attributed to Bi−O covalent bonds; the Bi−O and Bi−Br of Ag SAs-BOB catalysts are shifted compared to Ag NPs-BOB, which may be because the anchoring of silver single atoms causes a certain degree of distortion in the BOB lattice structure, proving the existence of silver in single-atom form.
[0057] Figure 5 The graphs show the relationship between product yield and CH4 selectivity for x%wt Ag SAs-BOB (x = 0.5–3) and CH4 yield over time (b); and the relationship between product yield and CO selectivity for 1%wt Ag SAs-BOB synthesized under different light sources (c) and CO yield over time (d). After the introduction of silver single atoms, the CH4 yield of the x% Ag SAs-BOB series catalysts was significantly increased. After 4 hours of reaction, the CH4 yield of BOB was 15.20 μmol·g⁻¹. -1 The highest CH4 yield was observed with 1% Ag SAs-BOB, at 150.40 μmol·g. -1 It increased by 9.89 times. Figure 5 (d)(e) show the yield of CH4 and CO over time, as well as the total product and CH4 selectivity in the four-cycle experiment of Ag SAs-BOB. In the long-term test, the yield and selectivity of CH4 and CO did not change much, indicating that Ag SAs-BOB has high long-term stability.
[0058] Figure 6 XPS spectra of Ag NPs-BOB and Ag SAs-BOB: (a) Ag 3d, (b) Bi 4f, (c) Br 3d, (d) O 1s. The fine XPS spectra of both catalysts show clear signals of Ag, Bi, Br, and O elements. Analysis of the Ag 3d XPS spectrum indicates that the studied Ag element exists in its oxidized state. However, the peak of the silver single-atom catalyst shows a rightward shift compared to the silver nanoparticle catalyst, indicating a higher electron cloud density at the Ag sites in the silver single-atom catalyst. For the Bi 4f XPS spectrum, both catalysts show Bi... 3+ and Bi + The two oxidation states of Bi are due to the lattice oxygen (O) in BOB.2− The generation of oxygen vacancies during the synthesis process proves the existence of oxygen vacancies in Ag SAs-BOB. Comparison with the fine elemental spectra of XPS shows that the elemental binding energy of silver single atoms is lower than that of silver nanoparticles, indicating that the introduction of single-atom-sized Ag can improve the electron density on the catalyst surface to a greater extent than that of nanoparticle Ag.
[0059] Figure 7 (a) shows the UV-Vis DRS spectra of BOB, Ag SAs-BOB and Ag NPs-BOB. The light absorption capacity of Ag SAs-BOB photocatalyst is significantly better than that of BOB and Ag NPs-BOB. Figure 7 (b) is the Tauc spectrum obtained by the Kubelka-Munk conversion function. The incorporation of single-atom silver reduces the band gap of the photocatalyst to 2.06 eV, which is better than that of silver nanoparticle loading. Figure 7 (c) shows the valence band XPS spectra of Ag SAs-BOB and Ag NPs-BOB. It is clear that the photoluminescence signal intensity of Ag SAs-BOB is significantly reduced, indicating that the photogenerated electron-hole recombination process of Ag SAs-BOB is effectively suppressed compared with Ag NPs-BOB and BOB. Figure 7 (d) and (e) show the Mott-Schottky diagrams of Ag NPs-BOB and Ag SAs-BOB, and the valence band bottom (VBM) level positions of BOB, Ag SAs-BOB, and Ag NPs-BOB are systematically analyzed. Through slope analysis of the linear region of the Mott-Schottky (MS) curves, both Ag NPs-BOB and Ag SAs-BOB exhibit typical N-type semiconductor characteristics. 7(f) shows the band structure diagrams of BOB, Ag SAs-BOB, and Ag NPs-BOB.
[0060] Figure 8 (a) Electrochemical impedance spectroscopy (EIC) plots for BOB, Ag SAs-BOB, and Ag NPs-BOB. Ag SAs-BOB exhibits a smaller radius of curvature than Ag NPs-BOB and BOB, indicating that the Ag SAs-BOB catalyst has a lower interfacial charge transfer resistance. Figure 8 (b) shows the photocurrent response diagram. The photocurrent response of Ag SAs-BOB has a higher photocurrent density, indicating that the single-atom-sized Ag significantly promotes the separation process of photogenerated carriers and accelerates their transfer rate. Figure 8 (c) The photoluminescence signal intensity of the fluorescence emission spectrum is significantly reduced, indicating that the recombination process of photogenerated electron-hole in Ag SAs-BOB is effectively suppressed compared with Ag NPs-BOB and BOB. Figure 8(d) shows the time-resolved fluorescence decay spectrum of Ag SAs-BOB. It is evident that the average lifetime of photogenerated electrons in Ag SAs-BOB is increased to 750 ps compared to Ag NPs-BOB (595 ps) and BOB (279 ps). This indicates that single-atom-sized silver effectively suppresses the recombination process of photogenerated carriers and effectively prolongs the lifetime of photogenerated electrons, which is beneficial for driving the deep reduction and efficient conversion of photocatalyzed CO2.
[0061] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention.
Claims
1. A method for preparing silver-atom-anchored oxygen-rich defect bromine tri-bismuth oxide nanosheet photocatalyst, characterized in that, Includes the following steps: 1) Dissolve bismuth nitrate pentahydrate and silver nitrate in ethylene glycol and label the solution as solution A; 2) Dissolve hexadecyltrimethylammonium bromide and polyvinylpyrrolidone in ethylene glycol and label it as solution B; 3) Sonicate solutions A and B for 5 minutes each to ensure uniform dispersion; Slowly add solution A to B and adjust the pH to 11.5; 4) The mixed solution was transferred to a stainless steel high-pressure reactor and kept at 160 °C for 12 h. Finally, the precipitate was washed six times with deionized water and ethanol alternately. After centrifugation, the solid precipitate was collected, dried, and silver single-atom anchored oxygen-rich defect bismuth tetroxide nanosheets (Ag SAs-Bi3O4Br, Ag SAs-BOB) were obtained.
2. The production method according to claim 1, wherein In Ag SAs-BOB nanosheets, with Bi3O4Br nanosheets as the base (100%), the loading of silver single atoms is 0.5-3 wt%.
3. The preparation method according to claim 1, characterized in that, In step 1, 3184.88 mg of bismuth nitrate pentahydrate was weighed and dissolved in 25 mL of ethylene glycol.
4. The preparation method according to claim 1, characterized in that, In step 1, the added AgNO3 was 14.70 mg to 88.20 mg depending on the loading amount.
5. The preparation method according to claim 1, characterized in that, In step 2, 1457.80 mg of cetyltrimethylammonium bromide and 5 mg of polyvinylpyrrolidone were weighed and dissolved in 25 mL of ethylene glycol.
6. The preparation method according to claim 1, characterized in that, In step 4, the pH of the solution is adjusted to 11.5 using 2 mol / L sodium hydroxide (NaOH).
7. The preparation method according to claim 1, characterized in that, In step 5, the stainless steel high-pressure reactor is lined with Teflon, and the hydrothermal reactor is kept at 160 °C for 12 h.
8. The preparation method according to claim 1, characterized in that, In step 5, the solid precipitate is dried in a vacuum oven at 60 °C for more than 12 h.