Method for detecting catalytic performance of photocatalyst based on crystal face effect

Abstract

The invention relates to the technical field of photocatalysts, in particular to a method for detecting the catalytic performance of a photocatalyst based on a crystal face effect. The microscopic confocal Raman spectrometer is combined with the surface enhanced Raman technology, so that the spatial resolution is relatively high, and the method can be used for revealing a microscopic mechanism generated by photocatalytic ROS. According to the method, SERS substrates are modified on different crystal faces of the Pt / BiVO4 crystal, after a catalytic light source is applied, ROS signals amplified after the SERS substrates are adsorbed on the specific crystal faces can be detected along with illumination time, the variety and yield of ROS generated by the different crystal faces of the Pt / BiVO4 crystal can be analyzed through Raman spectrum analysis, and then the regulation and control mechanism of crystal face modification on photocatalytic ROS can be explained.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalysts, and in particular to a method for detecting the catalytic performance of a photocatalyst based on a crystal plane effect. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The rapid economic development and continuous environmental changes have caused a series of environmental pollution problems. At present, a variety of organic pollutants have been detected in water bodies, and effective methods are urgently needed to degrade these organic pollutants. Among the many degradation methods, photocatalytic degradation is undoubtedly one of the most promising methods. Photocatalytic degradation refers to the use of light energy to excite photocatalysts to produce reactive oxygen species (ROS), thereby degrading organic pollutants.

[0004] However, traditional photocatalysts have problems such as low separation efficiency of electrons and holes and easy recombination, which makes the photocatalytic degradation efficiency low. In recent years, scientists have proposed various methods to optimize the activity of photocatalysts, including constructing heterojunctions, generating oxygen vacancies, constructing Schottky junctions and crystal face engineering. Selective modification of metals on the surface of photocatalysts with crystal face effects is a flexible and controllable activity regulation strategy, which has attracted the attention of a large number of researchers. Due to the crystal face effect, the electrons and holes generated by the photocatalyst will be directional and separated to different crystal faces. The modification of metals on different crystal faces will affect the path of their electrons and holes being converted into ROS on the catalytic surface, resulting in differences in the reactive oxygen species and yields generated on different crystal faces. However, the path of ROS generation between crystal faces and the mechanism of metal regulation on photocatalytic efficiency on different crystal faces are still unclear. In addition, the process of photocatalytic ROS generation is dynamic and is affected by factors such as different crystal faces of the photocatalyst and the metal materials modified on the surface. These processes are not only spatial and temporal states, but also involve surface reactions at the microscopic scale. To study the regulatory effect of the selective modification of noble metals to different crystal faces of photocatalysts on ROS, a real-time in situ characterization technology is needed. However, it is difficult to detect the ROS generated by different crystal faces of photocatalyst particles under light conditions using existing technical methods, and it is even more difficult to analyze the mechanism of catalyst performance improvement by analyzing the types of ROS generated by different crystal faces of photocatalysts. Summary of the invention

[0005] In order to overcome the above problems, the present invention provides a method for detecting the catalytic performance of a photocatalyst based on the crystal plane effect.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A method for detecting the catalytic performance of a photocatalyst based on a crystal face effect, comprising:

[0008] SERS substrates were modified on different crystal faces of photocatalysts based on crystal face effect, and a single photocatalyst modified with SERS substrate was transferred to a gold-coated glass slide. A cover glass was used to assemble the single photocatalyst modified with SERS substrate and the gold-coated glass slide into a sandwich structure. Water was dripped into the sandwich structure under the irradiation of visible light, and a Raman spectrometer was used to detect the types and yields of ROS generated by the photocatalyst based on crystal face effect.

[0009] In one or more embodiments, the photocatalyst based on the crystal plane effect is preferably a Pt / BiVO4 crystal, and the Pt / BiVO4 crystal includes a 010 crystal plane and a 110 crystal plane.

[0010] Preferably, the preparation method of the Pt / BiVO4 crystal comprises:

[0011] BiVO4 crystals are dispersed in an ethanol aqueous solution, to which an H2PtCl6 aqueous solution is added. At room temperature, a 455nm wavelength lamp is used for continuous illumination for 2 to 4 hours. After the reaction is completed, Pt / BiVO4 crystals are obtained.

[0012] In one or more embodiments, the SERS substrate is Au@Pt core-shell nanoparticles.

[0013] Preferably, the method for modifying Au@Pt core-shell nanoparticles on the 010 crystal plane and the 110 crystal plane of the Pt / BiVO4 crystal comprises:

[0014] Gold nanoparticles (Au NPs) are synthesized by a seed growth method, and Au@Pt core-shell nanoparticles (Au@Pt NPs) are synthesized by a seed-mediated method; the Au@Pt core-shell nanoparticles are dispersed in water to form an Au@Pt core-shell nanoparticle dispersion;

[0015] The Au@Pt core-shell nanoparticle dispersion was placed in a photoreaction tube, and Pt / BiVO4 crystals were added. The mixture was stirred in the dark, and then the entire photoreaction tube was placed in a photoreactor for reaction for 1 to 2 hours, so that the Au@Pt core-shell nanoparticles were modified on the 010 crystal surface of the Pt / BiVO4 crystal.

[0016] The Au@Pt core-shell nanoparticle dispersion was placed in a photoreaction tube, polyaniline (PDDA) was added, the reaction was stirred, centrifuged and washed to obtain polyaniline-modified Au@Pt core-shell nanoparticles, the polyaniline-modified Au@Pt core-shell nanoparticles were dispersed in water, Pt / BiVO4 crystals were added, and then isopropanol was added and the pH value of the solution was adjusted to 4 using a buffer solution. The solution was stirred in the dark, and the entire photoreaction tube was placed in a photoreactor to react for 1 to 2 hours, thereby modifying the Au@Pt core-shell nanoparticles on the 110 crystal plane of the Pt / BiVO4 crystal.

[0017] Under the condition of light, the electrons and holes of the photocatalyst are directionally separated to different crystal planes, and the electrons transfer holes to the 010 crystal plane and transfer electrons to the 110 crystal plane. Therefore, under the condition of light, the 010 crystal plane has a positive charge and the 110 crystal plane has a negative charge; the surface of Au@Pt core-shell nanoparticles synthesized by the seed-mediated method has a negative charge, so the Au@Pt core-shell nanoparticles will be adsorbed on the 010 crystal plane through electrostatic action; the Au@Pt core-shell nanoparticles are modified by polyaniline, so that the surface of the polyaniline-modified Au@Pt core-shell nanoparticles has a positive charge, and the positively charged polyaniline-modified Au@Pt core-shell nanoparticles are again adsorbed on the 110 crystal plane through electrostatic action.

[0018] In one or more embodiments, the thickness of gold on the gold-plated glass sheet is 40-60 nm, preferably 50 nm.

[0019] In one or more embodiments, the sandwich structure includes a gold-coated glass sheet, on which a single photocatalyst modified with a SERS substrate is placed, a first cover glass is arranged on both sides of the photocatalyst, a second cover glass is arranged above the photocatalyst, and the second cover glass is connected to the first cover glass. The first cover glass arranged on both sides of the photocatalyst leaves a gap between the upper surface of the catalyst and the second cover glass, and there is also a gap between the first cover glass and the catalyst, and the gap here can be used to add solvent water. At the same time, since the amount of ROS generated by a single photocatalyst is limited, a large amount of water will interfere with the measurement of the ROS signal, so the large gap between the first cover glass and the second cover glass can eliminate the interference of a large amount of water.

[0020] In one or more embodiments, a HORIBA confocal Raman spectrometer is used to detect the generation of ROS by photocatalysts based on the crystal face effect, wherein the HORIBA confocal Raman spectrometer uses an excitation wavelength of 633 nm, a 50x telephoto objective lens, a laser attenuation power of 10%, and a wavelength collection range of 400 to 1300 cm -1 , all calibrated using silicon wafers.

[0021] In one or more embodiments, the power of the visible light source is 5-20 W, preferably 10 W, and the wavelength is 405 nm.

[0022] The beneficial effects of the present invention are:

[0023] (1) Microscopic confocal Raman spectrometer combined with surface enhanced Raman technology has high spatial resolution and can be used to reveal the microscopic mechanism of photocatalytic ROS generation. In the present invention, SERS substrates are modified on different crystal faces of Pt / BiVO4 crystals. After applying a catalytic light source, the ROS signal amplified by the adsorption of the SERS substrate on a specific crystal face can be detected with the illumination time. By analyzing the Raman spectrum, the types and yields of ROS generated by different crystal faces of Pt / BiVO4 crystals can be analyzed, and then the regulatory mechanism of crystal face modification on photocatalytic ROS can be explained.

[0024] (2) Au@Pt NPs have a plasma resonance effect, and Pt easily bonds with O, playing the role of ROS capture and surface enhanced Raman signal. The gold-coated glass sheet can ensure light transmittance while eliminating the Raman signal interference of the glass sheet. By modifying the SERS substrate on different crystal faces of the photocatalyst with crystal face effect, the ROS signal amplification detection of a single crystal face can be achieved.

[0025] (3) The method provided by the present invention for detecting the catalytic performance of a photocatalyst based on the crystal face effect is applicable to the detection of ROS on different crystal faces of all photocatalysts based on the crystal face effect, and has universal applicability.

[0026] (4) The method provided by the present invention for detecting the catalytic performance of photocatalysts based on crystal face effect makes it possible to study the mechanism of ROS generation by small particle photocatalysts with crystal face effect, and has good practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] Figure 1 a is the SEM image of decahedral BiVO4 crystal, b and c are the SEM images and HRTEM images of Pt / BiVO4 crystal;

[0029] Figure 2 XRD diagrams of BiVO4 crystal and Pt / BiVO4 crystal;

[0030] Figure 3Transmission electron microscopy images of Au NPs, Au@Pt NPs and polyaniline-modified Au@Pt core-shell nanoparticles; A is Au NPs; B is Au@Pt NPs; C is Au@Pt NP (scale bar: 100nm), inset: local morphology of Au@Pt NP (scale bar: 1nm); D is modified Au@PtNPs+PDDA, scale bar in A, B, D: 400nm;

[0031] Figure 4 A is a single molecule image of BiVO4 photocatalyst in 500nM AR fluorescent probe solution, B is a single molecule image of BiVO4 photocatalyst in 500nM Re fluorescent probe solution; C is the Zeta potential diagram of Au NPs, Au@Pt NPs and Au@PtNPs+PDDA;

[0032] Figure 5 A is a SEM image of Au@Pt NPs selectively adsorbed on the 110 crystal plane of the photocatalyst Pt / BiVO4 crystal, and B is a SEM image of polyaniline-modified Au@Pt NPs selectively adsorbed on the 010 crystal plane of the photocatalyst Pt / BiVO4 crystal;

[0033] Figure 6 Schematic diagram of using Raman spectroscopy to detect the types of ROS generated by photocatalysts based on crystal face effects;

[0034] Figure 7 A diagram of a device for detecting the types of ROS generated by a photocatalyst based on the crystal face effect using a Raman spectrometer;

[0035] Figure 8 To verify whether Au@Pt NPs will produce active intermediate signals under light conditions to interfere with the ROS signal measurement results generated by the photocatalyst, A is Au@Pt NPs; B is modified Au@Pt NPs;

[0036] Fig. 9 To verify whether the selective modification of the SERS substrate affects the intrinsic peak of the photocatalyst, A is the standard Raman peak of decahedral BiVO4; B is the Raman peak of the SERS substrate adsorbed on different crystal planes;

[0037] Fig.10 Time-dependent Raman spectra of ROS generated by Pt / BiVO4 crystals on different crystal planes, A is the 010 crystal plane and B is the 110 crystal plane. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0041] Example 1

[0042] 1.1 First, completely dissolve 3mmol Bi(NO3)3·5H2O in 30mL of 1M HNO3 aqueous solution and stir at room temperature for 30min to form a solution. Then, add 3mmol NH4VO3 to the solution and stir vigorously for 1h to obtain a solution. Then adjust the pH value of the solution to 1.25 with ammonia water until an orange precipitate is formed. After aging for 30min, transfer the precipitate to a 100mL polytetrafluoroethylene autoclave and hydrothermally treat it at 100℃ for 48h. Decahedral BiVO4 crystals are obtained. The SEM image of the decahedral BiVO4 crystals is shown in the figure. Figure 1 As shown in a.

[0043] Add 0.2 mL of anhydrous ethanol, 1.8 mL of deionized water, 20 mg of BiVO4 and 22.8 μL of 1 g / L H2PtCl6 aqueous solution to the photoreaction tube. Irradiate continuously for 3 hours at room temperature using a 455 nm wavelength lamp. After the reaction is completed, wash three times with deionized water, centrifuge at 3000 rpm for 3 minutes, and then dry in an oven at 80°C overnight to obtain BiVO4 crystals loaded with Pt co-catalysts, namely Pt / BiVO4 crystals. The SEM and HRTEM images of the Pt / BiVO4 crystals are shown in Figure 1. Figure 1 As shown in b and c.

[0044] BiVO4 crystal and Pt / BiVO4 crystal XRD Figure 2 As shown, from Figure 2It can be seen that the diffraction peaks of BiVO4 crystal and Pt / BiVO4 crystal are basically the same. The diffraction peaks at 18.53°, 18.85°, 28.77°, 30.38°, 34.38°, and 35.05° can be divided into {110}, {011}, {121}, {040}, {200}, and {002} crystal planes of BiVO4. All diffraction peaks show monoclinic phase BiVO4 (JCPDS No.14–0688). Due to the low content and small size of Pt NPs, Pt / BiVO4 does not show Pt diffraction peaks. The XRD spectrum shows that the modification of Pt NPs will not affect the crystal structure of BiVO4.

[0045] 1.2 Preparation of Au NPs

[0046] Au NPs were prepared using the seed growth method. Step 1: Synthesis of seed solution: In a 200mL round-bottom flask, heat 150mL of 2.2mM sodium citrate solution to boiling, then inject 1mL of 25mM (i.e., HAuCl4 with a mass fraction of 1%, the same concentration is used in the subsequent steps) chloroauric acid (HAuCl4) solution, the solution color changes from yellow to blue-gray and then to pink; cool to 90°C, inject 1mL of HAuCl4 solution, react for 30min; then inject 1mL of HAuCl4 solution, react for 30min. Step 2: Take 55mL of the seed solution from the first step, add 53mL and 2mL of 60mM sodium citrate solution, heat to boiling, inject 1mL of HAuCl4 solution, react for 30min; cool to 90°C, inject 1mL of HAuCl4 solution, react for 30min; then inject 1mL of HAuCl4 solution, react for 30min. Step 3: Treat the solution synthesized in the second step as a seed and repeat the experimental operation in the second step. This process was repeated five times in total to obtain an Au NPs solution of about 120 nm.

[0047] Preparation of Au@Pt NPs

[0048] Au NPs solution (30 mL) was stirred vigorously in a round-bottom flask, 18.5 μL (3.8 mg / mL, Pt) H2PtCl6 solution was added, heated to 80°C, and 180 μL ascorbic acid (1.721 mg dissolved in 1 mL water) was added under stirring. After thorough mixing, it was stored at 80°C for 30 min and then cooled to room temperature. Au@Pt core-shell nanoparticles were obtained by centrifugal washing three times.

[0049] Polyaniline modified Au@PtNPs

[0050] Take 15mL Au@Pt NPs in an eggplant-shaped bottle, add 1mL PDDA, and stir in a magnetic stirrer for 1h. Take out and ultrasonicate for 1min every 20min, for a total of three times. After the reaction is complete, centrifuge and ultrasonicate for washing, repeat three times, and store in aqueous solution.

[0051] Figure 3 Transmission electron microscopy images of Au NPs, Au@Pt NPs, and polyaniline-modified Au@Pt core-shell nanoparticles. Figure 3 As can be seen in the figure, the synthesized Au NPs are evenly dispersed and spherical; the surface of a single Au@Pt NP is rough, and the Pt layer is composed of uniform and dense nanoparticles, and the thickness of the Pt layer is about 0.32nm. After the Au@Pt NPs were treated with the strong cationic polymer PDDA, the particle size did not change, but there was aggregation and adhesion, and it was easy to restore the uniform dispersion state under ultrasonic conditions.

[0052] 1.3 Take 2 mL of Au@Pt NPs in a photoreaction tube, add 5 mg of Pt / BiVO4, mix and stir evenly in the dark for 5 minutes, and place it in a photoreactor to react for 1 hour, that is, Au@Pt core-shell nanoparticles are modified on the 010 crystal surface of the Pt / BiVO4 crystal.

[0053] Take 2mL of Au@Pt NPs modified with polyaniline in a photoreaction test tube, add 5mg of Pt / BiVO4, add 0.3mL of isopropanol and use buffer solution to adjust the pH value of the solution to 4, mix and stir evenly in the dark for 5min, place it in a photoreactor to react for 1h, and after the reaction, the precipitate is washed three times with water and stored for later use, that is, Au@Pt core-shell nanoparticles are modified on the 110 crystal face of the Pt / BiVO4 crystal.

[0054] Figure 4 A is the single molecule image of BiVO4 photocatalyst in 500nM AR fluorescent probe solution, B is the single molecule image of BiVO4 photocatalyst in 500nM Re fluorescent probe solution; C is the Zeta potential diagram of Au NPs, Au@Pt NPs and Au@PtNPs+PDDA.

[0055] like Figure 4 As shown in Figure A, under illumination conditions, the fluorescence signal of the BiVO4 photocatalyst in a 500nM AR fluorescent probe solution with the addition of the electron sacrificial agent methyl viologen is mainly distributed on the 110 face of the particles. The experimental results show that under illumination conditions, the holes of the BiVO4 photocatalyst gather on the 110 crystal face of the particles. Figure 4As shown in Figure B, under illumination, in a 500nM Re fluorescent probe solution with methanol as a hole sacrificial agent, the fluorescence signal of the BiVO4 photocatalyst is mainly distributed on the 010 face of the particle. The experimental results show that under illumination, the electrons of the BiVO4 photocatalyst gather on the 010 crystal face of the particle. The decahedral BiVO4 photocatalyst can achieve a good directional separation of electrons and holes under illumination. Figure 4 As shown in C, Au NPs and Au@Pt NPs are negatively charged; after modifying the surface of Au@Pt NPs with a strong cationic polymer PDDA, the modified Au@Pt NPs dispersed in water after three centrifugal washings are positively charged. Therefore, it is feasible to achieve selective adsorption of SERS substrates by relying on the mutual attraction between the positive and negative charges of the particles. Under the condition of light, the electrons and holes of the photocatalyst are directionally separated to different crystal planes, and the electrons transfer holes to the 010 crystal plane and transfer electrons to the 110 crystal plane. Therefore, under the condition of light, the 010 crystal plane has a positive charge and the 110 crystal plane has a negative charge; the surface of Au@Pt core-shell nanoparticles synthesized by the seed-mediated method has a negative charge, so the Au@Pt core-shell nanoparticles will be adsorbed on the 010 crystal plane through electrostatic action; the Au@Pt core-shell nanoparticles are modified by polyaniline, so that the surface of the polyaniline-modified Au@Pt core-shell nanoparticles has a positive charge, and the positively charged polyaniline-modified Au@Pt core-shell nanoparticles are again adsorbed on the 110 crystal plane through electrostatic action.

[0056] Figure 5 In the figure, A represents Au@Pt NPs selectively adsorbed on the 110 crystal plane of the photocatalyst Pt / BiVO4 crystal, and B represents polyaniline-modified Au@Pt NPs selectively adsorbed on the 010 crystal plane of the photocatalyst Pt / BiVO4 crystal.

[0057] Example 2

[0058] The gold-plated glass sheet used in this embodiment has the following specific dimensions: width 2.5 cm, length 7.6 cm, Au thickness 50 nm, and is then cut into 5×5 mm. The thickness of the first cover glass and the second cover glass are 0.17 mm and 18×18 mm, respectively.

[0059] In order to reduce the interference of dust and organic pollutants on the Raman signal under the excitation light source, the gold-coated glass slide, glass slide and cover glass were first thoroughly cleaned.

[0060] The specific method includes: immersing the gold-plated glass sheet, glass sheet and cover glass in glass cleaner, and performing ultrasonic cleaning for three times for 5 minutes. After being fully rinsed with deionized water, they are immersed in anhydrous ethanol separately, and ultrasonic cleaning is performed for three times for 5 minutes. Finally, after being fully rinsed with deionized water, they are placed in a blast drying oven, dried and sealed for storage.

[0061] 2.1 The liquid after the reaction in the photoreactor in Example 1.3 (including Pt / BiVO4 crystals modified with Au@Pt core-shell nanoparticles on the 010 crystal plane and Pt / BiVO4 crystals modified with Au@Pt core-shell nanoparticles on the 110 crystal plane) was directly dropped onto a gold-coated glass sheet. Since the concentration of crystals in the dispersion was very low, the crystals were dispersed in a single particle. The interface of a single catalyst was selected through a microscope, and the entire device was placed in an oven and dried at 80°C overnight.

[0062] A single photocatalyst modified with a SERS substrate and a gold-coated glass sheet are assembled into a sandwich structure using a cover glass. Specifically, the sandwich structure includes a gold-coated glass sheet, on which a single photocatalyst modified with a SERS substrate is placed, a first cover glass is arranged on both sides of the photocatalyst, a second cover glass is arranged above the photocatalyst, and the second cover glass is connected to the first cover glass. The first cover glass arranged on both sides of the photocatalyst leaves a gap between the upper surface of the catalyst and the second cover glass, and there is also a gap between the first cover glass and the catalyst, and the gap here can be used to add solvent water. At the same time, since the amount of ROS generated by a single photocatalyst is limited, a large amount of water will interfere with the measurement of the ROS signal, so the large gap between the first cover glass and the second cover glass can eliminate the interference of a large amount of water.

[0063] 2.2 Raman spectroscopy is used to detect the types of ROS generated by photocatalysts based on the crystal face effect. The schematic diagram of the detection process is shown in Figure 6 shown.

[0064] The HORIBA confocal Raman spectrometer was used to detect the generation of ROS by photocatalysts based on the crystal face effect. The HORIBA confocal Raman spectrometer used an excitation wavelength of 633 nm, a 50x telephoto objective lens, a laser attenuation power of 10%, and a wavelength collection range of 400 to 1300 cm -1 , all calibrated with silicon wafers. A visible light source with a power of 10w and a wavelength of 405nm is set just below the detection window of the confocal Raman spectrometer. Figure 7 shown.

[0065] Raman spectroscopy was started as soon as the catalytic light source was turned on, and a Raman spectrum was collected every 10 seconds, with a total collection time of two minutes.

[0066] 2.21 First, verify whether Au@Pt NPs will produce active intermediate signals under light conditions to interfere with the ROS signal measurement generated by the photocatalyst (such as Figure 8 ). Under the illumination of 455nm blue LED light, the SERS substrate signal changes over time are collected. All Raman spectra are calibrated with silicon wafers before testing. Figure 8 As shown in A, under light conditions, no obvious active intermediate signal is generated in the aqueous solution of Au@Pt NPs. Figure 8 As shown in B, under illumination, there is no obvious peak in the aqueous solution of modified Au@Pt NPs. The experimental results show that the SERS substrate does not generate ROS under illumination.

[0067] In order to verify whether the selective modification of the SERS substrate affects the intrinsic peak of the photocatalyst, the Raman peak of the photocatalyst adsorbed on the SERS substrate was detected in a dark environment. Fig. 9 A shows the standard Raman peak of decahedral BiVO4. The standard peak position of BiVO4 is 324.6 cm -1 、367.5cm -1 、640.4cm -1 、709.9c m-1 and 828.9cm -1 .like Fig. 9 As shown in B, compared with the standard Raman peak of BiVO4, adsorbing the SERS substrate on different crystal planes does not change the intrinsic peak position of the photocatalyst.

[0068] 2.22 Fig.10 Time-dependent Raman spectra of ROS generated by Pt / BiVO4 crystals on different crystal planes, A is the 010 crystal plane and B is the 110 crystal plane.

[0069] like Fig.10 As shown in A, two active oxygen species were detected on the 010 crystal surface of Pt / BiVO4: OOH and O2 ·- , the peak positions are 737cm -1 and 1077cm -1 .like Fig.10 As shown in B, two active oxygen species were detected on the 110 crystal plane of Pt / BiVO4: ·OOH and ·OH, with peaks at 695 cm -1 、727cm -1 and 958cm -1 The experimental results show that the 110 crystal plane of Pt / BiVO4 undergoes electrons and O2 to generate O2 ·- The reaction and O2 ·- To ·OOH; On the 110 crystal plane, not only the reaction of holes and H2O to generate ·OH but also the reaction of electrons and O2 to generate O2 ·- The Pt NPs on the 110 crystal plane and the Pt NPs on the 010 crystal plane both have the ability to adsorb oxygen and transfer electrons, resulting in O2 ·- and the production of its transformation products.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting the catalytic performance of a photocatalyst based on a crystal face effect, characterized in that: include: SERS substrates were modified on different crystal faces of photocatalysts based on crystal face effect, and a single photocatalyst modified with SERS substrate was transferred to a gold-coated glass slide. A cover glass was used to assemble the single photocatalyst modified with SERS substrate and the gold-coated glass slide into a sandwich structure. Water was added to the sandwich structure under the irradiation of visible light, and a Raman spectrometer was used to detect the types of ROS generated by the photocatalyst based on crystal face effect.

2. The method according to claim 1, characterized in that The photocatalyst based on the crystal plane effect is a Pt / BiVO4 crystal, and the Pt / BiVO4 crystal includes a 010 crystal plane and a 110 crystal plane.

3. The method according to claim 2, characterized in that The preparation method of the Pt / BiVO4 crystal comprises: BiVO4 crystals are dispersed in an ethanol aqueous solution, to which an H2PtCl6 aqueous solution is added. At room temperature, a 455nm wavelength lamp is used for continuous illumination for 2 to 4 hours. After the reaction is completed, Pt / BiVO4 crystals are obtained.

4. The method according to claim 2, characterized in that The SERS substrate is Au@Pt core-shell nanoparticles.

5. The method according to claim 4, characterized in that The method for modifying Au@Pt core-shell nanoparticles on the 010 crystal plane of Pt / BiVO4 crystal includes: synthesizing gold nanoparticles by a seed growth method, and then synthesizing Au@Pt core-shell nanoparticles by a seed-mediated method; dispersing the Au@Pt core-shell nanoparticles in water to form an Au@Pt core-shell nanoparticle dispersion; The Au@Pt core-shell nanoparticle dispersion was placed in a photoreaction tube, Pt / BiVO4 crystals were added, stirred in the dark, and the entire photoreaction tube was placed in a photoreactor to react for 1 to 2 hours, thereby modifying the Au@Pt core-shell nanoparticles on the 010 crystal surface of the Pt / BiVO4 crystal.

6. The method according to claim 5, characterized in that The method for modifying Au@Pt core-shell nanoparticles on the 110 crystal plane of Pt / BiVO4 crystal includes: The Au@Pt core-shell nanoparticle dispersion was placed in a photoreaction tube, polyaniline was added, the reaction was stirred, centrifuged and washed to obtain polyaniline-modified Au@Pt core-shell nanoparticles, the polyaniline-modified Au@Pt core-shell nanoparticles were dispersed in water, Pt / BiVO4 crystals were added, and then isopropanol was added and the pH value of the solution was adjusted to 4 using a buffer solution. The solution was stirred in the dark, and the entire photoreaction tube was placed in a photoreactor to react for 1 to 2 hours, thereby modifying the Au@Pt core-shell nanoparticles on the 110 crystal plane of the Pt / BiVO4 crystal.

7. The method according to claim 1, characterized in that The sandwich structure includes a gold-plated glass sheet, on which a single photocatalyst modified with a SERS substrate is placed, first cover glass sheets are arranged on both sides of the photocatalyst, a second cover glass sheet is arranged above the photocatalyst, and the second cover glass sheet is connected to the first cover glass sheet.

8. The method according to claim 1, characterized in that The HORIBA confocal Raman spectrometer was used to detect the generation of ROS by photocatalysts based on the crystal face effect. The HORIBA confocal Raman spectrometer used an excitation wavelength of 633 nm, a 50x telephoto objective lens, a laser attenuation power of 10%, and a wavelength collection range of 400 to 1300 cm -1 , all calibrated using silicon wafers.

9. The method according to claim 1, characterized in that The power of the visible light source is 5-20W, preferably 10W; and the wavelength is 405nm.

10. The method according to claim 1, characterized in that The thickness of gold on the gold-plated glass sheet is 40-60 nm, preferably 50 nm.

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