Preparation method and application of cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst

Abstract

The invention relates to a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, wherein the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction is composed of a (001) diffraction crystal plane of mesoscopic niobium pentoxide and a (002) diffraction crystal plane of cadmium zinc sulfide. Preparation method: adding mesoscopic niobium pentoxide during the hydrothermal growth of cadmium zinc sulfide, and obtaining the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst through secondary hydrothermal treatment. Application of the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst in catalytic oxidation degradation and reduction of antibiotics under visible light. Application of the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst in catalytic oxidation degradation and reduction of antibiotics to produce hydrogen under visible light. Beneficial effects are as follows: the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst has superior photocatalytic performance, and due to the formation of the S-type heterojunction, it has stronger light absorption capacity and higher carrier separation efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalysis, and in particular to a preparation method and application of a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst. Background Art

[0002] The domestic sewage generated rapidly in the process of industrialization and urbanization has exceeded the self-purification capacity of natural water bodies; the excessive discharge of comprehensive sewage has also caused damage to the water environment and the survival of various aquatic plants and animals, thus affecting human health and development. The ecological environment in my country's traditional energy-rich areas is mostly fragile. Energy development and utilization will put great pressure on the ecological environment, affecting my country's ecological security and social stability. Therefore, effectively alleviating environmental pollution problems and developing clean, cheap, and renewable energy are major scientific and technological challenges facing my country in achieving sustainable development and improving people's quality of life, which has attracted widespread attention from scientific and technological workers.

[0003] As a secondary energy source, hydrogen energy has the advantages of high energy density and only produces water as a combustion product. It is considered to be one of the best candidates to replace traditional fossil energy. The reaction of decomposing water to produce hydrogen and the reaction of degrading pollutants in wastewater have the same liquid phase carrier. If hydrogen energy is obtained and organic pollutants in wastewater are degraded at the same time, it will achieve the effect of killing two birds with one stone. Therefore, developing clean energy represented by hydrogen energy and degrading pollutants in water at the same time is an effective strategy to solve the problems of fossil fuel shortage and environmental pollution.

[0004] In recent years, photocatalytic technology, as a clean, efficient and environmentally friendly technology, has shown good application prospects in the fields of pollution control, environmental restoration and clean energy development. Niobium pentoxide nanofibers prepared by electrospinning can also be assembled into a unique three-dimensional network, which is more conducive to the reuse of photocatalysts in the field of photocatalytic hydrogen production. It has the advantages of large specific surface area, short ion migration path, and unique one-dimensional electron transfer orbit, which can greatly improve the efficiency of photocatalytic water decomposition to produce hydrogen. However, there is no public report on the use of niobium pentoxide fibers in the treatment of antibiotic-containing wastewater.

[0005] In summary, we proposed a preparation method of CdZnS nanosheets / mesoscopic NbO2 nanofibers for the simultaneous production of clean hydrogen during antibiotic wastewater treatment. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method and application of a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst to solve the problems of high cost of photocatalytic degradation of antibiotics and low efficiency of a single niobium pentoxide catalyst in the above-mentioned prior art.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, wherein the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction is composed of the (001) diffraction crystal plane of the mesoscopic niobium pentoxide and the (002) diffraction crystal plane of the cadmium zinc sulfide.

[0008] The beneficial effects of the present invention are as follows: the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst has excellent photocatalytic performance, and due to the formation of the S-type heterojunction, it has stronger light absorption capacity and higher carrier separation efficiency.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, in the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, cadmium zinc sulfide is uniformly attached to the surface of mesoscopic niobium pentoxide to form a closely contacted heterojunction structure.

[0011] Based on the above technical scheme, the present invention also provides a method for preparing a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, in which mesoscopic niobium pentoxide is added during the hydrothermal growth process of cadmium zinc sulfide, and a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst is obtained through secondary hydrothermal growth.

[0012] The above further beneficial effect is: a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst for antibiotic degradation and hydrogen energy generation is prepared by a simple hydrothermal method, and the synthesis process is simple and the cost is low.

[0013] Furthermore, the mass fraction of mesoscopic niobium pentoxide in the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst is 10% to 40%.

[0014] The above further beneficial effect is: by changing Cd 0.5 Zn 0.5 By adjusting the ratio of S and Nb2O5, photocatalysts with different mass ratios can be obtained.

[0015] Further, the specific preparation steps of cadmium zinc sulfide are as follows:

[0016] A1. Mix zinc acetate, ultrapure water and ethylenediamine and perform hydrothermal reaction to obtain a white powder;

[0017] A2, dispersing the white powder obtained in A1 in ethylene glycol, adding cadmium chloride, and hydrothermally reacting to obtain a yellow powder;

[0018] A3. Disperse the yellow powder obtained in A2 in ultrapure water and perform hydrothermal reaction to obtain a light yellow powder, namely cadmium zinc sulfide.

[0019] Further, the specific preparation steps of mesoscopic niobium pentoxide are as follows:

[0020] B1. Dissolve niobium ethoxide in ethanol and acetic acid, and add PVP K90 to obtain a transparent solution;

[0021] B2. Add the transparent solution into the syringe, connect the syringe needle to a self-flowing high-voltage power supply, adjust the voltage and injection rate, and obtain a white fiber membrane;

[0022] B3. Calcine the white fiber membrane to obtain mesoscopic niobium pentoxide.

[0023] Furthermore, the specific preparation steps of the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst are as follows:

[0024] The yellow powder obtained in A2 is dispersed in ultrapure water, and the mesoscopic niobium pentoxide obtained in B3 is added to undergo a hydrothermal reaction to obtain a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst.

[0025] Furthermore, the hydrothermal reaction temperature in A1 was 160 °C and the time was 20 h;

[0026] In A2, the hydrothermal reaction temperature is 160 °C and the time is 8 h;

[0027] In A3, the hydrothermal reaction temperature is 120 °C and the time is 6 h;

[0028] In B2, the voltage was 16 kV and the injection rate was 500 μL / h;

[0029] The calcination temperature in B3 is 750°C and the calcination time is 2h.

[0030] Based on the above technical solution, the present invention also provides an application of a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst in catalytic oxidation degradation and reduction of antibiotics under visible light.

[0031] The above further beneficial effects are: in situ X-ray photoelectron spectroscopy analysis proves that the composite photocatalyst is an S-type heterojunction photocatalyst, and the photocatalytic performance test results show that the photocatalyst can effectively degrade or completely mineralize antibiotic pollutants in wastewater under visible light irradiation, with an efficiency of more than 90%, and the degradation rate is still more than 90% after five cycles, proving that the S-type heterojunction photocatalyst has excellent activity and stability under visible light irradiation, and is an efficient, green and safe environmental purification technology.

[0032] Based on the above technical solution, the present invention also provides an application of a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst to produce hydrogen in the catalytic oxidation degradation and reduction of antibiotics under visible light.

[0033] The above further beneficial effect is that hydrogen can be produced while treating wastewater, and its average hydrogen production rate reaches Cd 0.5 Zn 0.5 More than 3 times of S. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Cd 0.5 Zn 0.5 S, Nb2O5 and series Cd 0.5 Zn 0.5 X-ray diffraction pattern of S / Nb2O5 sample;

[0035] Figure 2 Cd 0.5 Zn 0.5 Transmission electron microscopy image of S / 20% Nb2O5;

[0036] Figure 3 Cd 0.5 Zn 0.5 S, Nb2O5 and series Cd 0.5 Zn 0.5 In-situ X-ray photoelectron spectroscopy of S / 20% Nb2O5 sample;

[0037] Figure 4 Cd 0.5 Zn 0.5 S, Nb2O5 and series Cd 0.5 Zn 0.5 Photocatalytic degradation of antibiotics by S / Nb2O5 sample;

[0038] Figure 5 Cd 0.5 Zn 0.5 Photocatalytic degradation of antibiotics coupled with hydrogen production performance of S / 20% Nb2O5. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0040] Example 1

[0041] A cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst. The cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction is composed of the (001) diffraction crystal plane of the mesoscopic niobium pentoxide and the (002) diffraction crystal plane of the cadmium zinc sulfide. The cadmium zinc sulfide is uniformly attached to the surface of the mesoscopic niobium pentoxide to form a closely contacted heterojunction structure.

[0042] The preparation method of cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst comprises the following specific steps:

[0043] Preparation of cadmium zinc sulfide:

[0044] A1, 0.44 g of zinc acetate was dissolved in a mixed solution of 20 mL of ultrapure water and 50 mL of ethylenediamine, and subjected to hydrothermal reaction at 160 °C for 20 h to obtain a white powder;

[0045] A2, disperse the white powder in A1 into 60 mL of ethylene glycol, take 0.0839 g of cadmium chloride and dissolve it in the mixed solution, and perform hydrothermal reaction at 160 °C for 8 h to obtain a yellow powder;

[0046] A3, disperse the yellow powder in A2 into 60 mL of ultrapure water and perform hydrothermal reaction at 120 °C for 6 h to obtain a light yellow powder;

[0047] Step A4, washing and drying the light yellow precipitate in A3 in sequence to obtain cadmium zinc sulfide;

[0048] Preparation of mesoscopic niobium pentoxide:

[0049] B1, dissolve 0.78g of niobium ethoxide in a mixed solution of 5mL of ethanol and 2mL of acetic acid, dissolve 0.35g of PVP K90 in the mixed solution, and stir vigorously to obtain a transparent solution;

[0050] B2, add the transparent solution obtained in B1 into the syringe, connect the needle to the DC high voltage power supply, adjust the voltage to 16kV, and the injection rate is 500μL / h to obtain a white fiber membrane;

[0051] B3, the white fiber membrane obtained in B2 was placed in a muffle furnace and calcined at 750°C for 2 hours to obtain a white substance, thereby obtaining mesoscopic niobium pentoxide;

[0052] Preparation of CdZnS / mesoscopic NbO2 S-type heterojunction fiber photocatalyst:

[0053] C1, dispersing the yellow powder obtained in A2 into ultrapure water, and adding the mesoscopic niobium pentoxide obtained in B3, wherein the yellow powder obtained in A2 and the mesoscopic niobium pentoxide obtained in B3 are mixed in a mass ratio of 90:10, and subjected to hydrothermal reaction at 120° C. for 6 hours to obtain a light yellow substance;

[0054] C2, the light yellow substance obtained in C1 was washed and dried in sequence to obtain cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, marked as Cd 0.5 Zn 0.5 S / 10%Nb2O5.

[0055] Example 2

[0056] The difference between this embodiment and embodiment 1 is that the yellow powder obtained in A2 and the mesoscopic niobium pentoxide obtained in B3 are mixed in a mass ratio of 80:20, and are marked as Cd 0.5 Zn 0.5 S / 20%Nb2O5.

[0057] Example 3

[0058] The difference between this embodiment and embodiment 1 is that the yellow powder obtained in A2 and the mesoscopic niobium pentoxide obtained in B3 are mixed in a mass ratio of 60:40, and are marked as Cd 0.5 Zn 0.5 S / 40%Nb2O5.

[0059] The present invention changes Cd 0.5 Zn 0.5 The photocatalysts with different mass ratios can be obtained by adjusting the ratio of S and Nb2O5. The in-situ X-ray photoelectron spectroscopy analysis proves that the composite photocatalyst is an S-type heterojunction fiber photocatalyst. For the above embodiments, cadmium zinc sulfide is in the form of cadmium zinc sulfide nanosheets, and the mesoscopic niobium pentoxide is in the form of mesoscopic niobium pentoxide nanofibers. The photocatalytic performance test results show that the photocatalyst can effectively degrade the antibiotic molecules in the wastewater under visible light irradiation with an efficiency of more than 90%, and the degradation rate is still more than 90% after five cycles, which proves that the S-type heterojunction fiber photocatalyst has excellent activity and stability under visible light irradiation; while treating wastewater, it can produce hydrogen, and its average hydrogen production rate reaches Cd 0.5 Zn 0.5 The catalyst is easy to prepare and has low cost.

[0060] from Figure 1 It can be seen that the synthesized Cd 0.5 Zn 0.5 S and Nb2O5 and different proportions of Cd 0.5 Zn 0.5 The crystal structure and composition of S / Nb2O5 composite photocatalyst were characterized;

[0061] In the XRD spectrum of the composite sample, Cd 0.5 Zn 0.5 S / 10%Nb2O5、Cd 0.5 Zn 0.5 S / 20% Nb2O5 and Cd 0.5 Zn 0.5 Cd can be observed in the XRD diffraction pattern of S / 40% Nb2O5 0.5 Zn 0.5The characteristic peaks of S and Nb2O5, the typical characteristic peaks correspond to the (001) diffraction crystal plane of Nb2O5, Cd 0.5 Zn 0.5 The (002) diffraction crystal plane of S preliminarily confirmed that the composite photocatalyst has good crystallinity and possesses the common properties of the two monomers.

[0062] from Figure 2 It can be seen that Nb2O5 exhibits a typical mesoscopic fibrous morphology with a thin layer of nanosheets attached to the surface, which is Cd 0.5 Zn 0.5 S;

[0063] In addition, the heterojunction interface of the two monomers intertwined can be clearly observed from the figure, confirming the formation of the heterojunction photocatalyst.

[0064] from Figure 3 It can be seen that Cd 0.5 Zn 0.5 The binding energy of Nb 3d orbital of S / 20% Nb2O5 shifts toward the low binding energy direction compared with Nb2O5, and shifts toward the high binding energy direction under UV irradiation. This result indicates that the photogenerated electrons are hybridized from Nb2O5 to Cd 0.5 Zn 0.5 S is offset, constructing an S-type electron transfer path that stabilizes the electron flow and generates a built-in electric field on the heterojunction interface. This built-in electric field helps Cd 0.5 Zn 0.5 S / Nb2O5 and effectively separate the charge carriers.

[0065] Combination Figure 2 and Figure 3 , which can confirm that Cd 0.5 Zn 0.5 The S / Nb2O5 composite photocatalyst is an S-type heterojunction photocatalyst.

[0066] Figure 4 Cd under visible light irradiation 0.5 Zn 0.5 S, Nb2O5 and series Cd 0.5 Zn 0.5 The photocatalytic degradation of antibiotics by S / Nb2O5 samples shows that compared with monomers Nb2O5 and Cd 0.5 Zn 0.5 S, the series of composite catalysts all showed better photocatalytic degradation activity than the monomers, among which Cd 0.5 Zn 0.5 S / 20%Nb2O5 sample compared with Cd 0.5 Zn 0.5 S / 10% Nb2O5 and Cd0.5 Zn 0.5 S / 40% Nb2O5 has the best photocatalytic degradation activity. After 60 minutes of visible light irradiation, more than 90% of ciprofloxacin molecules were effectively degraded.

[0067] from Figure 5 It can be seen that Cd 0.5 Zn 0.5 S / Nb2O5 catalyst can effectively degrade antibiotics and produce hydrogen at the same time; as shown in the figure, Cd 0.5 Zn 0.5 In the S / 20% Nb2O5 sample, ciprofloxacin molecules were degraded under visible light, and hydrogen was detected to continue to grow, with an average hydrogen production rate of 97 μmol g -1 h -1 , higher than Cd 0.5 Zn 0.5 S / 10% Nb2O5 and Cd 0.5 Zn 0.5 Hydrogen production effect of S / 40%Nb2O5.

[0068] The present invention uses photocatalytic technology: using light as energy, antibiotic pollutants can be completely mineralized. It is an efficient, green and safe environmental purification technology. A cadmium sulfide zinc / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst used for antibiotic degradation and generating hydrogen energy is prepared by a simple hydrothermal method. It has a simple synthesis process and low cost. The cadmium sulfide zinc / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst has excellent photocatalytic performance. Due to the formation of the S-type heterojunction, it has stronger light absorption ability and higher carrier separation efficiency.

[0069] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, It is characterized in that The cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction is composed of the (001) diffraction crystal plane of the mesoscopic niobium pentoxide and the (002) diffraction crystal plane of the cadmium zinc sulfide; The preparation method of cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst is as follows: B1. Dissolve niobium ethoxide in ethanol and acetic acid, and add PVP K90 to obtain a transparent solution; B2. Add the transparent solution into the syringe, connect the syringe needle to a self-flowing high-voltage power supply, adjust the voltage and injection rate, and obtain a white fiber membrane; B3, calcining the white fiber membrane to obtain mesoscopic niobium pentoxide; A1. Mix zinc acetate, ultrapure water and ethylenediamine and perform hydrothermal reaction to obtain a white powder; A2, dispersing the white powder obtained in A1 in ethylene glycol, adding cadmium chloride, and hydrothermally reacting to obtain a yellow powder; A3. The yellow powder obtained in A2 is dispersed in ultrapure water, and the mesoscopic niobium pentoxide obtained in B3 is added to carry out a hydrothermal reaction to obtain a cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst.

2. A cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst according to claim 1, Features: In the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst, cadmium zinc sulfide is uniformly attached to the surface of mesoscopic niobium pentoxide to form a closely contacted heterojunction structure.

3. The cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst according to claim 1, Features: The mass fraction of mesoscopic niobium pentoxide in the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst is 10% to 40%.

4. The cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst according to claim 1, Features: In A1, the hydrothermal reaction temperature was 160 °C and the time was 20 h; In A2, the hydrothermal reaction temperature is 160 °C and the time is 8 h; In A3, the hydrothermal reaction temperature is 120 °C and the time is 6 h; In B2, the voltage was 16 kV and the injection rate was 500 μL / h; The calcination temperature in B3 is 750°C and the calcination time is 2h.

5. Use of the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst as claimed in any one of claims 1 to 4 in catalytic oxidation degradation and reduction of antibiotics under visible light.

6. Use of the cadmium zinc sulfide / mesoscopic niobium pentoxide S-type heterojunction fiber photocatalyst as claimed in any one of claims 1 to 4 to produce hydrogen in the catalytic oxidation degradation and reduction of antibiotics under visible light.

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