Broadband spectral response type BiVO4-based photocatalytic electrode as well as preparation method and application thereof

Abstract

The invention discloses a broad-spectrum response type BiVO4-based photocatalytic electrode and a preparation method and application thereof, and belongs to the technical field of photocatalytic electrodes, the broad-spectrum response type BiVO4-based photocatalytic electrode comprises a conductive substrate and a photocatalyst loaded on the surface of the conductive substrate, and the photocatalyst is composed of BiVO4, a narrow-band gap semiconductor material and a cocatalyst; the preparation method comprises the following specific preparation steps: S1, preparing BiVO4 on the surface of a conductive substrate to obtain a BiVO4 electrode; s2, immersing the BiVO4 electrode into a Co salt solution, and applying potential to enable Co ions to be adsorbed on the surface of the BiVO4 electrode; and S3, immersing the BiVO4 electrode adsorbed with Co ions into a Na2S solution, washing and drying to obtain the wide-spectrum response type photocatalytic electrode. The narrow-band-gap semiconductor material Bi2S3 and the cocatalyst CoSx are prepared on the surface of BiVO4 in situ through an ion exchange method, the light absorption range of the BiVO4-based photocatalytic material can be effectively widened, and the photoelectric response signal of the BiVO4-based photocatalytic electrode under the excitation of visible light and near-infrared light is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic electrodes, and in particular to a wide-spectrum-responsive BiVO4-based photocatalytic electrode and a preparation method and application thereof. Background Art

[0002] The self-powered photoelectrochemical sensing method based on the development of photocatalytic fuel cells has the advantages of low cost, no need for external power supply, and easy miniaturization, and has emerged in the field of bioanalysis. In order to avoid damage to the biological molecules in this sensing system caused by high-energy photons, long-wave visible light or near-infrared light with good biocompatibility is often used as the excitation light source to construct the sensing system. Bismuth vanadate (BiVO4) is widely used in photocatalysis-related research due to its good optical properties, high carrier mobility and excellent anti-photocorrosion stability. However, the large bandgap width (~2.5eV) of bismuth vanadate means that it can only be excited by visible light with a wavelength less than 520nm, and it cannot effectively utilize the long-wave visible light and near-infrared light with a high proportion of sunlight and good biocompatibility.

[0003] Based on this, a wide-spectrum-responsive BiVO4-based photocatalytic electrode is proposed, which can not only improve its utilization efficiency of sunlight, but also promote its application in photoelectrochemical biosensors. Summary of the invention

[0004] The purpose of the present invention is to provide a BiVO4-based photocatalytic electrode with a wide spectrum response and a preparation method and application thereof, so as to solve the problems in the background technology.

[0005] To achieve the above object, the present invention provides a wide-spectrum-responsive BiVO4-based photocatalytic electrode, comprising a conductive substrate and a photocatalyst loaded on the surface of the conductive substrate, wherein the photocatalyst is composed of BiVO4, a narrow-bandgap semiconductor material and a co-catalyst.

[0006] Preferably, the narrow bandgap semiconductor material is Bi2S3, and the co-catalyst is CoS x .

[0007] Preferably, the conductive substrate is a conductive glass electrode, a glassy carbon electrode, a graphite electrode or a titanium electrode.

[0008] The present invention also provides a method for preparing a wide-spectrum-responsive BiVO4-based photocatalytic electrode, the steps of which are as follows:

[0009] S1, preparing BiVO4 on the surface of a conductive substrate to obtain a BiVO4 electrode;

[0010] S2, immersing the BiVO4 electrode in a Co salt solution, and applying a potential to adsorb Co ions on the surface of the BiVO4 electrode;

[0011] S3. Immerse the BiVO4 electrode adsorbed with Co ions in a Na2S solution, rinse and dry to obtain a wide-spectrum-responsive photocatalytic electrode.

[0012] Preferably, the specific steps of S1 are:

[0013] S11, electrodepositing a BiOI thin film on a conductive substrate;

[0014] S12. Using acetylacetonatovanadium as the vanadium source, BiOI is converted into BiVO4 at high temperature.

[0015] Preferably, the specific steps of S11 are:

[0016] 1) adding a bismuth salt solution to a solution containing KI, adjusting the pH, adding an ethanol solution of p-benzoquinone, and stirring to obtain an electrolyte;

[0017] 2) The conductive substrate is ultrasonically cleaned; then the conductive substrate after ultrasonic cleaning is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum sheet is used as a counter electrode, and a three-electrode system is used to electrodeposit the BiOI film.

[0018] Preferably, the specific steps of S12 are:

[0019] The electrodeposited BiOI film is dried, and after cooling, a dimethyl sulfoxide solution of vanadium acetylacetonate is drop-coated on the surface of the BiOI film, which is then placed in a muffle furnace for calcination. After cooling to room temperature, the film is immersed in a NaOH solution, rinsed with pure water, and dried in air to obtain a BiVO4 anode.

[0020] Preferably, in S12, the drying temperature is 80-120° C., the time is 30-45 min, the calcination temperature is 400-500° C., and the calcination time is 1.5-3 h.

[0021] Preferably, in S2, the Co salt concentration is 1 mmol / L -1 ~10mmolL -1 , the Co salt is one of cobalt nitrate, cobalt acetate or cobalt chloride; and the applied potential is 1V to 2V.

[0022] The invention applies a wide-spectrum-responsive BiVO4-based photocatalytic electrode to a near-infrared light-induced self-powered photoelectrochemical sensor.

[0023] Therefore, the present invention provides a wide spectrum response BiVO4-based photocatalytic electrode and its preparation method and application, and in situ prepares narrow bandgap semiconductor Bi2S3 and co-catalyst CoS on the BiVO4 surface by ion exchange. x, which solves the problem that BiVO4 is not easily excited by long-wavelength visible light and near-infrared light, and at the same time improves the photoelectrocatalytic performance of the BiVO4 electrode.

[0024] Specifically, bismuth sulfide is selected as a narrow bandgap semiconductor in the photocatalyst. It has a wide light absorption range and can form a wide spectrum response photocatalytic material with a matching energy level structure after coupling with BiVO4. The photogenerated electrons generated by the photocatalytic material after being excited can be spontaneously transferred from bismuth sulfide to bismuth vanadate, while the holes are transferred from bismuth vanadate with a lower valence band energy level to bismuth sulfide, so that the recombination of electron-hole pairs is significantly suppressed.

[0025] CoS catalyst x The loading of can increase the photocurrent of the photocatalytic electrode by reducing the activation energy of the oxygen evolution reaction, and further enhance the photoelectrochemical response of the composite photoelectrode under a wide spectrum; in the method of the present invention, the narrow bandgap semiconductor material Bi2S3 and the co-catalyst CoS are in situ prepared on the BiVO4 surface by an ion exchange method. x , realizing the construction of BiVO4-based photocatalytic electrode with wide spectrum response.

[0026] In addition, the wide spectrum response electrode prepared by the present invention is applied to a self-powered photoelectrochemical biosensor triggered by near-infrared light, which takes advantage of the low bleaching and low biological toxicity of near-infrared light, thereby improving the sensitivity and practicality of the sensing method.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The micro-region structure diagram of the photoelectrode prepared in the embodiment and comparative example of the present invention, wherein a is the embodiment and b is the comparative example;

[0029] Figure 2 The UV-Vis-NIR diffuse reflectance spectra of the photoelectrodes prepared in the examples and comparative examples of the present invention, wherein a is the example and b is the comparative example;

[0030] Figure 3 The photocurrent response diagram of the photoelectrodes prepared in the embodiments of the present invention and the comparative examples under illumination in the visible light (405 nm) band;

[0031] Figure 4 The photocurrent response diagram of the photoelectrodes prepared in the embodiments of the present invention and the comparative examples under near-infrared light (808 nm) band illumination;

[0032] Figure 5 A schematic diagram of a photocatalytic cell in an application example of the present invention;

[0033] Figure 6The following are the response diagrams and linear fitting diagrams of the self-powered photoelectrochemical sensor constructed based on the photocatalytic electrode prepared in the application example of the present invention to targets of different concentrations, wherein a is the response diagram to targets of different concentrations, and b is the linear fitting diagram. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0036] Example

[0037] The wide-spectrum-responsive BiVO4-based photocatalytic electrode was prepared using fluorine-doped tin oxide (FTO) conductive glass as the conductive substrate and BiVO4, Bi2S3, CoS x As a photocatalyst, the specific steps are as follows:

[0038] S1. Prepare BiVO4 on the surface of a conductive substrate to obtain a BiVO4 electrode, specifically:

[0039] 1) Add 0.97 g of Bi(NO3)3·5H2O to 50 mL of a solution containing 3.32 g of KI (the pH was adjusted to 1.7±0.1 in advance), then add 20 mL of an ethanol solution containing 0.49 g of p-benzoquinone, and stir to obtain an electrolyte;

[0040] 2) Cut the fluorine-doped tin oxide (FTO) conductive glass into small pieces of 2 cm × 2.5 cm, ultrasonically treat them in ethanol and saturated potassium carbonate methanol solution for 20 minutes respectively, and blow dry them with nitrogen. The cleaned FTO was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the platinum sheet was used as the counter electrode. Electrodeposition was performed at -0.1 V (vs SCE) for 300 s under a three-electrode system to obtain a uniform BiOI thin film electrode.

[0041] 3) Dry the BiOI thin film electrode at 100°C for 30 minutes, and after cooling, drop 200 μL of 0.2M acetylacetonato vanadyl dimethyl sulfoxide solution on the surface, calcine to 450°C at a heating rate of 2°C / min in a muffle furnace, and keep it for 2 hours; after cooling to room temperature, soak the electrode in 1M NaOH solution and shake it slowly to remove excess V2O5. Rinse with pure water and dry in air to obtain a BiVO4 photoanode.

[0042] S2. Immerse the BiVO4 electrode in a Co salt solution and apply a potential to adsorb Co ions on the surface of the BiVO4 electrode, specifically:

[0043] 80 mg of cobalt acetate tetrahydrate was dissolved in 120 mL of deionized water to form an electrolyte containing Co ions. A three-electrode system was built with BiVO4 electrode, saturated calomel electrode and platinum sheet as working electrode, reference electrode and counter electrode respectively, and the deposition was carried out at 2 V for 20 minutes to allow Co ions to be adsorbed on the surface of the BiVO4 electrode through the electric field.

[0044] S3, immerse the BiVO4 electrode adsorbed with Co ions in 0.03M Na2S solution and keep it for 10 minutes, and use the in-situ ion exchange reaction between Co ions, BiVO4 and Na2S to generate CoS on the surface x -Bi2S3, to obtain a BiVO4-based photocatalytic electrode with a wide spectrum response.

[0045] Comparative Example

[0046] In this comparative example, fluorine-doped tin oxide (FTO) conductive glass is used as the conductive substrate, BiVO4 is used as the photocatalyst, and the specific steps are the same as those in the embodiment, except that Bi2S3 and CoS x Steps to remove.

[0047] The products obtained in the examples and comparative examples were analyzed and tested, and their microstructures are shown in the following figure: Figure 1 The photocatalyst electrodes prepared in the examples and comparative examples were characterized by UV-visible-near infrared diffuse reflectance spectroscopy. Figure 2 shown.

[0048] UV-visible-near infrared diffuse reflectance spectroscopy shows that thanks to the narrow band gap of Bi2S3 (about 1.5 eV), CoS is in situ modified on the surface of BiVO4 photoelectrode. x -Bi2S3 can significantly enhance the absorption of visible and near-infrared light by BiVO4 photoelectrodes, so the photoelectrochemical system constructed based on the modified electrode can improve the utilization efficiency of the solar spectrum.

[0049] The photocatalytic electrodes prepared in the examples and comparative examples were subjected to photocurrent tests. During the test, the photocatalytic electrode was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the Pt wire electrode was used as the counter electrode to form a three-electrode system. The results are shown in FIG. Figure 3 , 4 As shown; it can be seen that under the excitation of visible light (405nm) or near-infrared light (808nm), CoS x-Bi2S3 can significantly improve the photoelectric signal of BiVO4 electrode, which is mainly due to the fact that the narrow-bandgap semiconductor bismuth sulfide enhances the absorption of light and promotes the migration of photogenerated carriers of BiVO4, as well as the catalyst CoS x Catalytic effect on water oxidation reaction.

[0050] The photocatalyst electrode prepared in the example is applied to a near-infrared light-induced self-powered photoelectrochemical sensor, as follows:

[0051] Application Examples

[0052] like Figure 5 As shown, the prepared CoS x -Bi2S3 / BiVO4 photocatalytic electrode was used as the photoanode, and the Prussian blue modified electrode was inserted into a quartz reaction cell filled with K2SO4 solution as the cathode, and connected through an external circuit to assemble into a single-chamber photocatalytic cell.

[0053] The photoanode is irradiated with an 808nm near-infrared light source, and the photoanode is excited to produce effective electron-hole pairs that separate and form a current path with the cathode, thereby generating electrical energy. The output performance of the battery is recorded and analyzed by an electrochemical workstation. The aptamer that can specifically recognize the target analyte, ethinyl estradiol, is modified on the surface of the photoanode as a recognition element. The determination of ethinyl estradiol is achieved by the decrease in battery output performance caused by the capture of the target analyte by the aptamer. The response diagram and linear fitting diagram of its self-powered photoelectrochemical sensor to different concentrations of targets are shown in the figure. Figure 6 As shown in the figure, the output performance of the photocatalytic cell constructed by the photoanode that captures different concentrations of ethinyl estradiol is demonstrated; the maximum output power of the photocatalytic cell has a good linear relationship with the logarithmic value of the ethinyl estradiol concentration, thereby realizing the near-infrared induced self-powered photoelectrochemical detection of ethinyl estradiol.

[0054] Therefore, the present invention provides a wide spectrum response BiVO4-based photocatalytic electrode and its preparation method and application, and in situ prepares narrow bandgap semiconductor material Bi2S3 and co-catalyst CoS on the BiVO4 surface by ion exchange method. x , realizing the construction of a BiVO4-based photocatalytic electrode with a wide spectrum response; and applying it to a self-powered photoelectrochemical biosensor triggered by near-infrared light, taking advantage of the low bleaching and low biological toxicity of near-infrared light, which is beneficial to improving the sensitivity and practicality of the sensing method.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A wide spectrum responsive BiVO4-based photocatalytic electrode, characterized in that: The invention comprises a conductive substrate and a photocatalyst loaded on the surface of the conductive substrate, wherein the photocatalyst is composed of BiVO4, a narrow bandgap semiconductor material and a co-catalyst.

2. A wide spectrum responsive BiVO4-based photocatalytic electrode according to claim 1, characterized in that: The narrow bandgap semiconductor material is Bi2S3, and the co-catalyst is CoS x .

3. The wide spectrum responsive BiVO4-based photocatalytic electrode according to claim 1, characterized in that: The conductive substrate is a conductive glass electrode, a glassy carbon electrode, a graphite electrode or a titanium electrode.

4. A method for preparing a wide-spectrum-responsive BiVO4-based photocatalytic electrode according to any one of claims 1 to 3, characterized in that: Here are the steps: S1, preparing BiVO4 on the surface of a conductive substrate to obtain a BiVO4 electrode; S2, immersing the BiVO4 electrode in a Co salt solution, and applying a potential to adsorb Co ions on the surface of the BiVO4 electrode; S3. Immerse the BiVO4 electrode adsorbed with Co ions in a Na2S solution, rinse and dry to obtain a wide-spectrum-responsive photocatalytic electrode.

5. The method for preparing a BiVO4-based photocatalytic electrode with a wide spectrum response according to claim 4, characterized in that: The specific steps of S1 are: S11, electrodepositing a BiOI thin film on a conductive substrate; S12. Using acetylacetonatovanadium as the vanadium source, BiOI is converted into BiVO4 at high temperature.

6. The method for preparing a BiVO4-based photocatalytic electrode with a wide spectrum response according to claim 5, characterized in that: The specific steps of S11 are: 1) adding a bismuth salt solution to a solution containing KI, adjusting the pH, adding an ethanol solution of p-benzoquinone, and stirring to obtain an electrolyte; 2) ultrasonically cleaning the conductive substrate; Then, the ultrasonicated conductive substrate was used as the working electrode, a saturated calomel electrode was used as the reference electrode, and a platinum sheet was used as the counter electrode, and a three-electrode system was used to electrodeposit the BiOI film.

7. The method for preparing a BiVO4-based photocatalytic electrode with a wide spectrum response according to claim 6, characterized in that: The specific steps of S12 are: The electrodeposited BiOI film is dried, and after cooling, a dimethyl sulfoxide solution of vanadium acetylacetonate is drop-coated on the surface of the BiOI film, which is then placed in a muffle furnace for calcination. After cooling to room temperature, the film is immersed in a NaOH solution, rinsed with pure water, and dried in air to obtain a BiVO4 anode.

8. The method for preparing a BiVO4-based photocatalytic electrode with a wide spectrum response according to claim 7, characterized in that: In the S12, the drying temperature is 80-120°C, the time is 30-45 minutes, the calcination temperature is 400-500°C, and the calcination time is 1.5-3 hours.

9. The method for preparing a BiVO4-based photocatalytic electrode with a wide spectrum response according to claim 4, characterized in that: In the S2, the Co salt concentration is 1mmolL -1 ~10mmolL -1 , the Co salt is one of cobalt nitrate, cobalt acetate or cobalt chloride; and the applied potential is 1V to 2V.

10. An application of the wide spectrum responsive BiVO4-based photocatalytic electrode according to any one of claims 1 to 3, characterized in that: The wide-spectrum-responsive BiVO4-based photocatalytic electrode was applied to a near-infrared light-induced self-powered photoelectrochemical sensor.

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