Preparation method of SnS2 catalyst with photo-piezoelectric catalytic synergistic effect

Abstract

The invention discloses a preparation method of a SnS2 catalyst with a photo-piezoelectric catalytic synergistic effect, SnCl4. 5H2O and CH4N2S are used as precursors to prepare a precursor solution, the precursor solution and carbon paper are put into a polytetrafluoroethylene lining, and a hydrothermal reaction is performed on the carbon paper to construct hexagonal SnS2 with a highly exposed (001) crystal face. It is found that the CO2 reduction rate of highly complete hexagonal SnS2 under the combined action of visible light and ultrasound is about 4 times of the performance of independent illumination; the hexagonal SnS2 with the highly exposed (001) crystal face prepared by the preparation method disclosed by the invention has a certain piezoelectric effect, and the hexagonal SnS2 prepared by the preparation method disclosed by the invention has an efficient photo-piezoelectric catalytic synergistic effect.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysis and piezocatalysis in semiconductor materials, and specifically relates to a preparation method of a SnS2 catalyst with photocatalytic-piezocatalytic synergy. Background Art

[0002] Photocatalytic CO2 reduction is a technology that uses light energy to convert CO2 into clean fuels such as CO, CH4, and C2H5OH. Compared with other technologies, it is safe and green. However, due to the complex reaction mechanism of CO2 reduction, the high reduction potential barrier, and the fast recombination of photo-generated carriers (the lifetime is only pS or nS), the photocatalytic CO2 reduction efficiency is low compared with other applications.

[0003] Piezoelectric materials, due to their non-centrosymmetric crystal structure, can generate a dipole moment when subjected to mechanical energy or strain, causing the centers of cations and anions in the unit cell to mismatch, thereby accumulating to generate a piezopotential field. Combining photocatalysis with piezocatalysis can largely compensate for the disadvantages of photocatalysis: First, the piezopotential generated by strain or vibration in piezoelectric materials can cause the energy band of the semiconductor to tilt, making the conduction band potential more negative, which enables some photocatalytic materials to satisfy or be more favorable for the thermodynamics reactions of some applications that require a higher reduction potential barrier; Second, the built-in potential field generated by piezoelectric materials can spatially separate photo-generated carriers and increase the lifetime of photo-generated carriers. By generating periodic vibrations through ultrasonic waves, it is possible to avoid the potential field that weakens the piezoelectric field caused by the long-term accumulation of separated electrons and holes on both sides due to the piezopotential field. Therefore, ultrasonic waves, this kind of mechanical vibration, are most used in the field of piezocatalysis.

[0004] SnS2 (two-dimensional layered transition metal sulfide) inevitably introduces a large number of dangling bonds and defects on the surface during conventional hydrothermal preparation. While increasing the adsorption of CO2 and pollutants, it also causes serious recombination of photo-generated carriers on the surface; and its relatively narrow bandgap results in a relatively positive actual conduction band position, and the driving force for photocatalytic CO2 reduction to CO is still insufficient. Summary of the Invention

[0005] Object of the Invention: The present invention proposes a preparation method of a SnS2 catalyst with photocatalytic-piezocatalytic synergy, constructs hexagonal SnS2 with highly exposed (001) crystal planes on carbon paper, and discovers that the (001) crystal plane has a positive effect on the photocatalytic-piezocatalytic synergy of SnS2 for CO2 reduction.

[0006] Technical Solution: A preparation method of a SnS2 catalyst with photocatalytic-piezocatalytic synergy proposed by the present invention includes the following steps:

[0007] Step 1: Ultrasonically clean the carbon paper and then dry it, and use plasma cleaning on the carbon paper;

[0008] Step 2: Prepare the precursor solution: Dissolve SnCl4·5H2O and CH4N2S in deionized water;

[0009] Step 3: Conduct hydrothermal reaction on the carbon paper and the precursor solution: Transfer the precursor solution to the inner lining of the reaction kettle, then place the carbon paper obliquely into the inner lining, seal the reaction kettle and move it to the hydrothermal box for hydrothermal reaction;

[0010] Step 4: After the reaction ends until the reaction kettle is completely cooled, take out the carbon paper with hexagonal SnS2 grown on it, wash the carbon paper sample multiple times and dry it.

[0011] Preferably, the plasma cleaning time in Step 1 is 20 min.

[0012] Preferably, in Step 1, ultrasonic cleaning is performed using acetone, ethanol, and deionized water, and the ultrasonic cleaning time is 20 min.

[0013] Preferably, in Step 2, the molar amount of SnCl4·5H2O is 0.9 mmol - 1.1 mmol, the molar amount of CH4N2S is 5.8 mmol - 6.2 mmol, and the deionized water is 30 ml.

[0014] Preferably, the inner lining of the reaction kettle is 50 ml of polytetrafluoroethylene.

[0015] Preferably, the hydrothermal reaction temperature is 190 °C and the reaction time is 12 h.

[0016] Preferably, the reaction formula of SnS2 is

[0017]

[0018] Preferably, in Step 4, the cleaning solution is deionized water and ethanol.

[0019] Preferably, in Step 4, drying is performed in a drying oven at 60 °C for 12 h.

[0020] Beneficial effects: In the present invention, hexagonal SnS2 with highly exposed (001) crystal planes is prepared on the carbon paper, and the influence of the hexagonal SnS2 with highly exposed (001) crystal planes on photo-piezoelectric catalytic CO2 reduction is analyzed. The hexagonal SnS2 with highly exposed (001) crystal planes has a certain piezoelectric effect, indicating that the photocatalytic CO2 reduction activity of the (001) crystal plane of SnS2 is relatively low, but the CO2 reduction rate caused by the photo-piezoelectric catalytic synergy effect is about 4 times that of adding light alone. The present invention utilizes the piezoelectric characteristics of hexagonal SnS2 to cause an efficient photo-piezoelectric catalytic synergy effect. Description of the Drawings

[0021] Figure 1XRD pattern of SnS2 grown on carbon paper obtained in Example 1;

[0022] Figure 2 SEM image of hexagonal SnS2 grown on carbon paper in Example 1;

[0023] Figure 3 Schematic diagram for piezoelectric test principle simulation of SnS2 grown on carbon paper;

[0024] Figure 4 CO2 reduction rate diagram of photocatalytic and photo-piezoelectric synergistic catalysis of hexagonal SnS2 grown on carbon paper. Detailed implementation mode

[0025] Example 1:

[0026] A preparation method of a SnS2 catalyst with photo-piezoelectric catalytic synergy, comprising the following steps:

[0027] Step 1: Ultrasonic clean the carbon paper in acetone, ethanol and deionized water for 20 min respectively. After drying, use plasma to clean the carbon paper for 20 min to increase its hydrophilicity, which is more conducive to the growth of SnS2 on the carbon paper;

[0028] Step 2: Prepare the precursor solution: Dissolve 1 mmol of SnCl4·5H2O and 6 mmol of CH4N2S in 30 ml of deionized water, and continuously stir for 30 min until completely dissolved and homogeneous;

[0029] Step 3: Transfer the above precursor solution to a 50 ml polytetrafluoroethylene inner liner. Place the plasma-cleaned hydrophilic carbon paper at an angle of 45° upward in the inner liner, seal it to the reaction kettle and transfer it to a hydrothermal box, and react at 190 °C for 12 h;

[0030] Step 4: After the reaction is completed, wait until the reaction kettle is completely cooled. Take out the carbon paper on which hexagonal SnS2 grows, rinse it several times with deionized water and ethanol, and dry it at 60 °C for standby.

[0031] Figure 1 The XRD pattern of SnS2 grown on carbon paper in Example 1 is shown. It can be found that the (001) crystal plane of SnS2 prepared in Example 1 has a very high intensity compared with other crystal planes, that is, the main exposed crystal plane is the (001) crystal plane; the diffraction peaks that do not belong to SnS2 of PDF#23-0677 are the diffraction peaks of the carbon paper.

[0032] Figure 2 This is the SEM image of SnS2 grown on carbon paper in Example 1. It can be found that the SnS2 prepared in Example 1 has a complete and single hexagonal SnS2 nanosheet structure, and its size is about 300 nm - 500 nm.

[0033] Figure 3 Figure 1 is a schematic diagram of the principle of a piezoelectric tester for SnS2 grown on carbon paper. By precisely controlling the mechanical stress applied to the piezoelectric material, and since the piezoelectric material generates induced charges, the charge changes generated are measured by the charging and discharging of the capacitor in the circuit amplifier, and the piezoelectric coefficient d is calculated by measuring the relationship between stress and charge. 33 . In order to obtain more accurate results, the carbon paper and SnS2 were each tested 3 times and the averages were taken. It was found that the carbon paper also had a certain piezoelectric coefficient of 23.16 (pC / N), and the high electrical conductivity of the carbon paper accelerated the carrier transport and could provide a high active surface for photo-piezoelectric catalysis. The piezoelectric coefficient of the hexagonal SnS2 prepared in Example 1 (28.23 (pC / N)) was higher than that of the carbon paper itself, indicating that the highly exposed (001) crystal plane hexagonal SnS2 had certain photo-piezoelectric catalytic ability.

[0034] Figure 4 Figure 2 is a diagram of the CO2 reduction rate of photo-catalysis and photo-piezoelectric synergistic catalysis of hexagonal SnS2 grown on carbon paper in Example 1. The hexagonal SnS2 with a highly exposed (001) crystal plane had low photo-catalytic performance. After adding ultrasound on this basis, the CO2 reduction performance of hexagonal SnS2 was greatly improved, but from Figure 4 it was found that the piezoelectric coefficient of hexagonal SnS2 was only slightly higher than that of the carbon paper itself, which reflected the strong synergistic effect of photo-piezoelectric catalysis of the highly exposed (001) crystal plane hexagonal SnS2.

[0035] Example 2

[0036] A preparation method of an SnS2 catalyst with photo-piezoelectric catalytic synergistic effect includes the following steps:

[0037] Step 1: Ultrasonic the carbon paper in acetone, ethanol and deionized water for 20 min respectively. After drying, use plasma to clean the carbon paper for 20 min to increase its hydrophilicity and be more conducive to the growth of SnS2 on the carbon paper;

[0038] Step 2: Prepare the precursor solution: Dissolve 0.9 mmol SnCl4·5H2O and 5.8 mmol CH4N2S in 30 ml of deionized water, and continuously stir for 30 min until completely dissolved and uniform.

[0039] Step 3: Transfer the above precursor solution to a 50 ml polytetrafluoroethylene inner liner, place the plasma-cleaned hydrophilic carbon paper at an angle of 45° upward in the inner liner, seal it to the reaction kettle and transfer it to the hydrothermal box, and react at 190 °C for 12 h;

[0040] Step 4: After the reaction is completed, wait until the reaction kettle is completely cooled. Take out the carbon paper with hexagonal SnS2 grown on it, rinse it several times with deionized water and ethanol, and dry it at 60 °C for standby.

[0041] Example 3

[0042] A preparation method of an SnS2 catalyst with photo-piezoelectric catalytic synergy includes the following steps:

[0043] Step 1: Ultrasonic clean the carbon paper in acetone, ethanol, and deionized water for 20 min respectively. After drying, use plasma to clean the carbon paper for 20 min to increase its hydrophilicity, which is more conducive to the growth of SnS2 on the carbon paper.

[0044] Step 2: Prepare the precursor solution: Dissolve 1.1 mmol of SnCl4·5H2O and 6.2 mmol of CH4N2S in 30 ml of deionized water, and continuously stir for 30 min until completely dissolved and uniform.

[0045] Step 3: Transfer the above precursor solution to a 50 ml polytetrafluoroethylene inner liner. Place the plasma-cleaned hydrophilic carbon paper at an angle of 45° upward in the inner liner, seal it in the reaction kettle and transfer it to a hydrothermal box, and react at 190 °C for 12 h.

[0046] Step 4: After the reaction is completed, wait until the reaction kettle is completely cooled. Take out the carbon paper with hexagonal SnS2 grown on it, rinse it several times with deionized water and ethanol, and dry it at 60 °C for standby.

Claims

1. A preparation method of a SnS2 catalyst with photo-piezoelectric catalytic synergy, characterized in that, It includes the following steps: Step 1: Ultrasonically clean the carbon paper and then dry it, and use plasma to clean the carbon paper; Step 2: Prepare the precursor solution: Dissolve SnCl4·5H2O and CH4N2S in deionized water; Step 3: Conduct a hydrothermal reaction on the carbon paper and the precursor solution: Transfer the precursor solution to the inner lining of the reaction kettle, then tilt the carbon paper and place it into the inner lining, seal the reaction kettle and move it to the hydrothermal box for hydrothermal reaction; Step 4: After the reaction ends until the reaction kettle is completely cooled, take out the carbon paper with hexagonal SnS2 grown on it, wash the carbon paper sample multiple times and dry it.

2. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, The plasma cleaning time in Step 1 is 20 min.

3. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 2, characterized in that, In Step 1, the ultrasonic cleaning uses acetone, ethanol, and deionized water, and the ultrasonic cleaning time is 20 min.

4. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, In Step 2, the molar amount of SnCl4·5H2O is 0.9 mmol - 1.1 mmol, the molar amount of CH4N2S is 5.8 mmol - 6.2 mmol, and the deionized water is 30 ml.

5. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, The inner lining of the reaction kettle is 50 ml of polytetrafluoroethylene.

6. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, The hydrothermal reaction temperature is 190 °C, and the reaction time is 12 h.

7. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, The reaction formula of SnS2 is 8. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, In Step 4, the cleaning solution is deionized water and ethanol.

9. The preparation method of the SnS2 catalyst with photo-piezoelectric catalytic synergy according to claim 1, characterized in that, In Step 4, the drying is carried out in a drying oven at 60 °C for 12 h.

10. A SnS2 catalyst with photo-piezoelectrocatalytic effect obtained by the preparation method according to any one of claims 1 - 9.

Images