Tin sulfide-resorcinol formaldehyde ladder-type photocatalyst with bionic structure as well as synthesis method and application of tin sulfide-resorcinol formaldehyde ladder-type photocatalyst

Abstract

The invention relates to a tin sulfide-resorcinol formaldehyde ladder type photocatalyst with a bionic structure. The tin sulfide-resorcinol formaldehyde ladder type photocatalyst is composed of resorcinol formaldehyde microspheres and a (002) diffraction crystal face of tin sulfide. The synthetic method of the tin sulfide-resorcinol formaldehyde ladder type photocatalyst with the bionic structure comprises the following step: adding resorcinol formaldehyde microspheres in a solvothermal growth process of tin sulfide to obtain the tin sulfide-resorcinol formaldehyde ladder type photocatalyst with the bionic structure. The tin sulfide-resorcinol formaldehyde ladder type photocatalyst with the bionic structure is applied to preparation of methanol by photocatalytic reduction of CO2 under visible light. The tin sulfide-resorcinol formaldehyde ladder-type photocatalyst with the bionic structure has the beneficial effects that the photocatalytic performance is excellent, due to the formation of a ladder-type heterojunction, the ladder-type photocatalyst has stronger light absorption capacity and higher carrier separation efficiency, the photocatalyst can reduce CO2 into liquid fuel methanol under the irradiation of visible light, and the methanol yield is 45.6 micromoles g <-1 > h <-1 >.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and particularly relates to a bionic structure tin sulfide - resorcinol formaldehyde ladder - type photocatalyst, a synthesis method thereof, and an application thereof. Background Art

[0002] In recent years, the energy crisis and environmental pollution problems are among the most severe problems currently faced globally. As a clean, efficient, and environmentally friendly technology, photocatalysis technology shows good application prospects in the fields of pollution treatment, environmental remediation, and clean energy development. The energy required for photocatalysis technology comes from solar energy, and solar energy has rich reserves and the advantages of being "inexhaustible and renewable", making it an ideal renewable energy source. Photocatalytic CO 2 reduction to produce solar fuels has the advantages of mild reaction conditions, low energy consumption, and simple operation, and is considered a clean energy technology with application prospects.

[0003] Among many semiconductor materials, metal sulfides are widely used due to their high electron mobility, large exciton binding energy, stable physical and chemical properties, non - toxicity, and low preparation cost. However, as a photocatalytic material, single - metal sulfides have problems such as narrow light absorption range, small particle size, difficult recovery, easy photocorrosion, and high surface free energy leading to easy agglomeration, which become the main obstacles to their efficient utilization. To obtain more ideal photocatalytic performance, the current main modification methods include: ion doping, noble metal modification, and construction of heterojunction photocatalysts, etc. Generally, the modification of a single semiconductor can improve its photocatalytic performance to a certain extent. However, its redox ability is inevitably restricted by the positions of the valence band and the conduction band. Therefore, constructing a multi - component heterojunction photocatalyst system can not only expand the light absorption range of the composite photocatalyst but also enhance the separation of photo - generated electron - hole pairs. If another type of semiconductor material with stable chemical properties can be selected to construct a heterojunction photocatalytic system with a metal sulfide photocatalyst, it can not only play the advantages of a single photocatalyst but also reduce costs and comprehensively improve the photocatalytic performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a bionic structure tin sulfide - resorcinol formaldehyde ladder - type photocatalyst, a synthesis method thereof, and an application thereof, so as to solve the problems of high cost and low efficiency of single - metal sulfide photocatalysts in the above - mentioned photocatalytic CO 2 reduction reaction.

[0005] The technical solution of the present invention to solve the above - mentioned technical problems is as follows:

[0006] The bionic structure tin sulfide - resorcinol formaldehyde ladder - type photocatalyst is composed of resorcinol formaldehyde microspheres and the (002) diffraction crystal plane of tin sulfide.

[0007] On the basis of the above technical solution, the present invention can be further improved as follows.

[0008] Further, in the bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst, tin sulfide is uniformly attached to the surface of the resorcinol formaldehyde microspheres, forming a bionic heterojunction structure with close contact.

[0009] Further, the tin sulfide in the bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst is 10% - 30% of the mass of the resorcinol formaldehyde microspheres.

[0010] Based on the above technical solution, the present invention also provides a method for synthesizing a bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst, comprising the following steps:

[0011] Add resorcinol formaldehyde microspheres during the solvothermal growth process of tin sulfide to obtain a bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst.

[0012] Further, the specific synthesis steps of the bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst are as follows:

[0013] S11. Mix tin chloride, ultrapure water, and ethanol, and continuously stir to obtain a transparent solution;

[0014] S12. Add resorcinol formaldehyde microspheres and thioacetamide to the transparent solution obtained in S11, and carry out a solvothermal reaction to obtain a bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst.

[0015] Furthermore, the continuous stirring time in S11 is 1 h.

[0016] Furthermore, the solvothermal reaction temperature is 160 °C - 200 °C, and the time is 3 h - 6 h.

[0017] Further, the synthesis steps of the resorcinol formaldehyde microspheres are as follows:

[0018] S21. Add resorcinol monomers to ultrapure water and continuously stir;

[0019] S22. While gradually dropping formaldehyde solution and concentrated ammonia water, and continuously carry out water bath heating to obtain a brown precipitate;

[0020] S23. Wash and dry the brown precipitate in sequence to obtain resorcinol formaldehyde microspheres.

[0021] Furthermore, the continuous stirring time in S21 is 1 h.

[0022] Furthermore, the dropping rate of formaldehyde is 1.0 mL / h - 2.0 mL / h, and the dropping rate of concentrated ammonia water is 0.2 mL / h - 0.5 mL / h.

[0023] Furthermore, the concentrated ammonia water is commercially available ammonia water with a concentration of 28%.

[0024] Furthermore, the water bath temperature is 80 °C and the time is 1 h to 4 h.

[0025] Based on the above technical solutions, the present invention also provides an application of the above bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst in photocatalytic reduction of CO 2 to methanol under visible light.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1) The bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst has excellent photocatalytic performance. Due to the formation of the ladder-type heterojunction, it has stronger light absorption ability and higher carrier separation efficiency.

[0028] 2) By changing the ratio of tin sulfide to resorcinol formaldehyde in the ladder-type photocatalyst, bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalysts with different mass ratios can be obtained.

[0029] 3) Only by the solvothermal method can a bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst for solar-driven CO 2 reduction to solar fuel be prepared. The synthesis process is simple and the cost is low.

[0030] 4) It is proved by in-situ X-ray photoelectron spectroscopy analysis that the composite photocatalyst is a bionic ladder-type heterojunction photocatalyst. The photocatalytic performance test results show that under visible light irradiation, the photocatalyst can reduce CO 2 to liquid fuel methanol, and the methanol yield is 45.6 μmol g -1 h -1 , and the methanol yield does not decay after ten cycles, proving that the bionic ladder-type heterojunction photocatalyst has excellent activity and stability under visible light irradiation and is an efficient, green and safe clean energy technology. Description of the Drawings

[0031] Figure 1 is the Fourier infrared spectrum of SnS 2 , RF and a series of SnS 2 / RF samples;

[0032] Figure 2 is the transmission electron microscope image of 20% SnS 2 / RF;

[0033] Figure 3 is SnS 2 and 20% SnS 2In-situ irradiation X-ray photoelectron spectroscopy diagram of the / RF sample;

[0034] Figure 4 is SnS 2 , RF and series of SnS 2 / RF sample for photocatalytic CO 2 Performance diagram for methanol production by reduction;

[0035] Figure 5 is 20% SnS 2 / RF sample for photocatalytic CO 2 Performance diagram for cyclic methanol production by reduction. Detailed implementation mode

[0036] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0037] Example 1

[0038] Bionic structure tin sulfide-resorcinol formaldehyde ladder-shaped photocatalyst, which is composed of resorcinol formaldehyde microspheres and the (002) diffraction crystal plane of tin sulfide, and tin sulfide in the bionic structure tin sulfide-resorcinol formaldehyde ladder-shaped photocatalyst is uniformly attached to the surface of resorcinol formaldehyde microspheres, forming a closely contacted bionic heterojunction structure.

[0039] Synthesis method of the bionic structure tin sulfide-resorcinol formaldehyde ladder-shaped photocatalyst, the specific steps are as follows:

[0040] S11. Mix 0.19 g of tin chloride, 30 mL of ultrapure water, and 30 mL of ethanol, and continuously stir. The stirring time can be 1 h to obtain a transparent solution;

[0041] S12. Add resorcinol formaldehyde microspheres and 0.2 g of thioacetamide to the transparent solution obtained in S11. Among them, tin sulfide in the bionic structure tin sulfide-resorcinol formaldehyde ladder-shaped photocatalyst is 10% of the mass of resorcinol formaldehyde microspheres, and carry out hydrothermal reaction at 160 °C to 200 °C for 3 h to 6 h to obtain a brownish-yellow substance, and wash and dry the obtained brownish-yellow substance in sequence to obtain the bionic structure tin sulfide-resorcinol formaldehyde ladder-shaped photocatalyst, marked as 10% SnS 2 / RF.

[0042] In this example:

[0043] Synthesis steps of resorcinol formaldehyde microspheres are as follows:

[0044] S21. Add 1.5 g of resorcinol monomer to 100 mL of ultrapure water, and continuously stir. The stirring time can be 1 h;

[0045] S22. While adding 2 mL of formaldehyde solution and 1.5 mL of concentrated ammonia water drop by drop simultaneously, the dropping rate of formaldehyde is 1.0 mL / h to 2.0 mL / h, and the dropping rate of concentrated ammonia water is 0.2 mL / h to 0.5 mL / h. Heat in a water bath at 80 °C for 1 h to 4 h, preferably 2 h, to obtain a brown precipitate;

[0046] S23. Wash and dry the brown precipitate in sequence to obtain resorcinol formaldehyde microspheres (RF).

[0047] The synthesis steps of tin sulfide are as follows:

[0048] S31. Mix 0.19 g of tin chloride, 30 mL of ultrapure water, and 30 mL of ethanol, and stir continuously. The stirring time can be 1 h to obtain a transparent solution;

[0049] S32. Add 0.2 g of thioacetamide to the transparent solution obtained in S31, and carry out a hydrothermal reaction at 160 °C to 200 °C for 3 h to 6 h to obtain a yellow powder, which is tin sulfide (SnS 2 ).

[0050] Example 2

[0051] The difference between this example and Example 1 is that the tin sulfide in the bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst is 20% of the mass of the resorcinol formaldehyde microspheres, and the obtained product is labeled as 20% SnS 2 / RF.

[0052] Example 3

[0053] The difference between this example and Example 1 is that the tin sulfide in the bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst is 30% of the mass of the resorcinol formaldehyde microspheres, and the obtained product is labeled as 30% SnS 2 / RF.

[0054] In the present invention, only by changing the mass ratio of SnS 2 and RF, photocatalysts with different mass ratios can be obtained. It is proved by in-situ irradiated X-ray photoelectron spectroscopy analysis that the composite photocatalyst is a bionic ladder-type heterojunction photocatalyst. For the above-mentioned examples, tin sulfide is in the form of thin-layer nanosheets, and resorcinol formaldehyde is in the form of microspheres. The results of photocatalytic performance tests show that the photocatalyst can reduce CO 2 to liquid fuel methanol under visible light irradiation, and the methanol yield is 45.6 μmol g -1 h -1 , and the methanol yield does not decay after ten cycles, proving that the bionic ladder-type heterojunction photocatalyst has excellent activity and stability under visible light irradiation, and is an efficient, green, and safe clean energy technology.

[0055] FromFigure 1 It can be seen that the synthesized SnS was characterized by Fourier transform infrared spectroscopy 2 , RF, and SnS with different ratios 2 / RF photocatalyst samples. In the Fourier transform infrared spectra of the SnS 2 / RF photocatalyst samples, characteristic peaks of RF could be observed in the Fourier transform infrared spectra of 10% SnS 2 / RF, 20% SnS 2 / RF, and 30% SnS 2 / RF.

[0056] As can be seen from Figure 2 , RF exhibited a typical microspherical morphology with thin nanosheets attached to its surface, which was SnS 2 , presenting a typical biomimetic structure. It was obvious from the figure that the intertwined heterointerface of the two monomers determined the formation of the heterojunction photocatalyst.

[0057] As can be seen from Figure 3 , the binding energy of the S2p orbital of 20% SnS 2 / RF shifted towards higher binding energy compared to SnS 2 , and shifted towards lower binding energy under ultraviolet light irradiation. This result indicated that the photoexcited electrons shifted from RF to SnS 2 during hybridization, constructing a ladder-shaped electron transfer path with a stable electron flow direction and generating a built-in electric field at the heterointerface. This built-in electric field contributed to the electron transfer at the SnS 2 / RF interface.

[0058] Combined with Figure 2 and Figure 3 , it could be confirmed that the SnS 2 / RF photocatalyst was a ladder-shaped heterojunction photocatalyst.

[0059] Figure 4 Shown is the performance graph of photocatalytic reduction of CO 2 to methanol by SnS 2 , RF, and SnS with different ratios 2 / RF photocatalysts under visible light irradiation. As can be seen from the figure, compared with the monomeric RF and SnS 2 , the series of composite catalysts all exhibited better photocatalytic activity than the monomers. Among them, the 20% SnS 2 / RF sample had the optimal photocatalytic performance for reducing CO 2 to methanol compared with 10% SnS 2 / RF and 30% SnS 2 / RF, with a methanol yield of 45.6 μmol g -1 h-1 .

[0060] From Figure 5 It can be seen that the methanol yield of the 20% SnS 2 / RF sample did not decay after ten cycles, demonstrating the excellent stability of the ladder-type heterojunction photocatalyst under visible light irradiation.

[0061] The present invention uses photocatalytic technology: with light as the energy, it can reduce CO 2 to liquid fuel methanol, which is an efficient, green and safe clean energy technology. A bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst for solar-driven CO 2 conversion is prepared by a simple solvothermal method. It has a simple synthesis process and low cost. The bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst has excellent photocatalytic performance. Due to the formation of the ladder-type heterojunction, it has stronger light absorption ability and higher carrier separation efficiency.

[0062] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A biomimetic structure tin sulfide-resorcinol formaldehyde ladder photocatalyst, characterized in that: It is composed of resorcinol formaldehyde microspheres and the (002) diffraction crystal plane of tin sulfide.

2. The biomimetic structure tin sulfide-resorcinol formaldehyde ladder photocatalyst according to claim 1, characterized in that: In the bionic tin sulfide-resorcinol formaldehyde ladder-type photocatalyst, tin sulfide is uniformly attached to the surface of the resorcinol formaldehyde microspheres to form a bionic heterojunction structure with close contact.

3. The biomimetic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst according to claim 1, characterized in that: In the bionic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst, the tin sulfide accounts for 10% to 30% of the mass of the resorcinol formaldehyde microspheres.

4. A method for synthesizing the biomimetic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst according to any one of claims 1 to 3, characterized in that: The steps include: Resorcinol formaldehyde microspheres are added into the solvent thermal growth process of tin sulfide to obtain a biomimetic structure tin sulfide-resorcinol formaldehyde ladder photocatalyst.

5. The synthesis method according to claim 4, characterized in that The specific synthesis steps of the biomimetic structure tin sulfide-resorcinol formaldehyde ladder photocatalyst are as follows: S11, mixing tin chloride, ultrapure water and ethanol, and continuously stirring to obtain a transparent solution; S12, adding resorcinol formaldehyde microspheres and thioacetamide to the transparent solution obtained in S11, and subjecting the solution to solvent thermal reaction to obtain a biomimetic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst.

6. The synthesis method according to claim 4 or 5, characterized in that: The solvent thermal reaction temperature is 160°C to 200°C, and the time is 3h to 6h.

7. The synthesis method according to claim 4, 5 or 6, characterized in that: The synthesis steps of resorcinol formaldehyde microspheres are: S21, adding resorcinol monomer to ultrapure water, and continuously stirring; S22, adding formaldehyde solution and concentrated ammonia water dropwise at the same time, and continuing to heat in a water bath to obtain a brown precipitate; S23, washing and drying the brown precipitate in sequence to obtain resorcinol formaldehyde microspheres.

8. The synthesis method according to claim 7, characterized in that The formaldehyde dripping rate is 1.0mL / h~2.0mL / h, and the concentrated ammonia water dripping rate is 0.2mL / h~0.5mL / h.

9. The synthesis method according to claim 7, characterized in that: The water bath temperature is 80°C and the time is 1h to 4h.

10. Use of the biomimetic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst as described in any one of claims 1 to 3 or the biomimetic structure tin sulfide-resorcinol formaldehyde ladder-type photocatalyst synthesized by the synthesis method as described in any one of claims 4 to 9 in the photocatalytic reduction of CO2 to produce methanol under visible light.

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