Co@MoS2 / carbon cloth composite piezocatalyst, and preparation method and application thereof

Abstract

The application discloses a Co@MoS2 / carbon cloth composite piezoelectric catalyst and a preparation method and application thereof, and the preparation method of the catalyst is as follows: a molybdenum / sulfur precursor solution and a cobalt source solution are prepared in advance; after the carbon cloth is cleaned and pretreated, the carbon cloth is moved into a reaction kettle together with the prepared molybdenum / sulfur precursor solution to perform a first hydrothermal reaction; after the reaction is completed, the prepared cobalt source solution is added into the reaction solution to continue to perform a second hydrothermal reaction; after the reaction is completed and cooled, the obtained carbon cloth is cleaned and dried to obtain the Co@MoS2 / carbon cloth composite piezoelectric catalyst. The Co@MoS2 / carbon cloth composite piezoelectric catalyst prepared by the application can utilize solar energy by using the carbon cloth as a black and gray textile product, and the Co@MoS2 as a semiconductor can utilize the photo catalytic capacity, so as to be used as a composite catalyst and be beneficial to better degradation and removal of pollutants.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of piezoelectric catalytic material preparation, and particularly relates to a Co@MoS2 / carbon cloth composite piezoelectric catalyst and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of global economy and the rapid growth of population, energy consumption and environmental damage have become a serious challenge. The capture, conversion and storage of clean and sustainable energy have attracted people's attention and great interest of researchers. Light, heat and mechanical energy are common forms of energy and clean energy, so the application of technologies related to such energy has also begun to develop. The ways to capture the above forms of energy include photoelectric effect, piezoelectric effect, pyroelectric effect and thermoelectric effect.

[0003] The essence of piezoelectric catalysis is that the piezoelectric effect generates electric charge, and the electric charge participates in chemical reactions. The piezoelectric effect refers to the direct conversion of mechanical energy into chemical energy, so it is also called piezoelectric electrochemistry (PZEC) effect. The piezoelectric effect can be divided into positive piezoelectric effect and inverse piezoelectric effect. The positive piezoelectric effect refers to the generation of electric charge on the surface of the piezoelectric material after deformation under external force, which is a mechanism that can convert mechanical energy into electrical energy. The inverse piezoelectric effect refers to the deformation of the piezoelectric material when an electric field is applied to the polarization direction of the piezoelectric material, which is a mechanism that can convert electrical energy into mechanical energy. Piezoelectric catalysis utilizes the positive piezoelectric effect, and the piezoelectric coefficient and the piezoelectric catalytic activity show a linear relationship. Piezoelectric materials can convert mechanical stress into electric charge.

[0004] A piezoelectric catalyst refers to the use of vibration energy to generate a piezoelectric potential in a piezoelectric material under the drive of a piezoelectric effect, thereby degrading pollutants. At the same time, mechanical energy, such as mechanical energy from vibration, water / air flow, sea waves and human movement, is ubiquitous, as is solar energy in the environment. Piezoelectric nanomaterials with non-centrosymmetric crystal structures can generate piezoelectricity through mechanical deformation. In a typical piezoelectric catalysis process, the piezoelectric material generates an internal electric field with external mechanical force, which can drive charge carriers (electrons and holes) to participate in redox reactions on the surface of the piezoelectric material and generate ROS in the surrounding medium. These generated ROS indicate the excellent redox ability of the piezoelectric catalyst, which can be used to degrade organic pollutants, including macromolecular dyes and antibiotics, etc. At the same time, the development of stable piezoelectric catalysts to adapt to more environmental organic pollutant degradation is needed.

[0005] Two-dimensional layered transition metal chalcogenides have been extensively studied in recent years due to their unique physicochemical properties. Among them, molybdenum disulfide (MoS2) is a graphene-like layered crystal with strong covalent Mo-S bonds within each monolayer and weak van der Waals forces between adjacent monolayers, allowing MoS2 to be easily exfoliated into monolayers. Furthermore, the interlayer spacing between adjacent MoS2 monolayers is 0.62 nm. MoS2 with trigonal prism polymorphic monolayers is a semiconductor (referred to as 2H), while monolayer MoS2 with an octahedral crystal symmetry structure (referred to as 1T) is metallic. MoS2 semiconductor piezoelectric catalysts are intrinsic piezoelectric materials with large piezoelectric coefficients. Thin sheets of molybdenum disulfide (MoS2) with an odd number of atomic layers exhibit piezoelectric properties. Single and odd-numbered layers of MoS2 can provide spatially different spontaneous polarization directions and exhibit a strong internal electric field that induces electron-hole pair separation to generate highly reactive free radicals, such as ·O. 2- ·OH and H2O2 are used for the degradation of organic matter. However, MoS2 has poor inherent conductivity, an inert basal surface, a limited number of active sites, and is prone to aggregation, so its catalytic ability needs to be further improved.

[0006] Carbon fiber cloth (CC) is an inexpensive and highly conductive textile that is readily available and possesses excellent mechanical flexibility and strength. It can be used as a carrier for Co@MoS2 to fix Co@MoS2 and adapt to different environmental terrains, while utilizing the mechanical forces present in nature to degrade some organic pollutants in water bodies. Summary of the Invention

[0007] To address the aforementioned technical problems in the existing technology, the present invention aims to provide a Co@MoS2 / carbon cloth composite piezoelectric catalyst, its preparation method, and its application.

[0008] The technical solution adopted in this invention is as follows:

[0009] The method for preparing a Co@MoS2 / carbon cloth composite piezoelectric catalyst is characterized by comprising the following steps;

[0010] 1) The molybdenum source and sulfur source are gradually added to deionized water and stirred in a water bath to dissolve them, thus obtaining a molybdenum / sulfur precursor solution for later use; the cobalt source is dissolved in deionized water to obtain a cobalt source solution for later use.

[0011] 2) After cleaning and pretreatment of the carbon cloth, it is transferred into the reactor together with the molybdenum / sulfur precursor solution prepared in step 1) for a first hydrothermal reaction. After the reaction is completed, the cobalt source solution prepared in step 1) is added to the reaction solution to continue the second hydrothermal reaction. After the reaction is completed and cooled, the obtained carbon cloth is cleaned and dried to obtain the Co@MoS2 / carbon cloth composite piezoelectric catalyst.

[0012] Furthermore, in step 1), the molybdenum source is ammonium heptamolybdate and the sulfur source is thiourea. The temperature at which the molybdenum source and the sulfur source are added to deionized water and stirred to dissolve is 40-60°C, and the stirring and dissolving time is 15-30 minutes, to ensure that both the molybdenum source and the sulfur source can be dissolved.

[0013] Further, in step 1), the molar ratio of the molybdenum source to the sulfur source is 1:2-6, preferably 1:4-4.5; the molar ratio of Co in the cobalt source to Mo in the molybdenum source is 1:35-105, preferably 1:70-80.

[0014] Furthermore, the cobalt source mentioned in step 1) is cobalt chloride.

[0015] Furthermore, in step 2), the carbon cloth is pre-treated by cleaning as follows: the carbon cloth is placed in acetone, anhydrous ethanol and deionized water for ultrasonic treatment, and the ultrasonic treatment time is 5 to 30 minutes.

[0016] Furthermore, in step 2), the temperature of the hydrothermal reaction is 180–220°C, and the reaction time is 20–30 hours.

[0017] Furthermore, in step 2), the temperature of the secondary hydrothermal reaction is 160–200°C, and the reaction time is 2–4 hours.

[0018] Furthermore, in the Co@MoS2 / carbon cloth composite piezoelectric catalyst prepared in step 2), the loading of Co@MoS2 on the carbon cloth is 3.0–5.0 mg / cm³. 2 .

[0019] This invention also provides the application of the prepared Co@MoS2 / carbon cloth composite piezoelectric catalyst in the piezoelectric-photocatalytic degradation of organic pollutants in wastewater. The application method includes the following steps:

[0020] ① The purpose of using wire mesh is to fix the Co@MoS2 / carbon cloth composite piezoelectric catalyst in place, preventing it from rotating with the water flow and maintaining it as a whole;

[0021] ② The wire mesh with Co@MoS2 / carbon cloth composite piezoelectric catalyst is fixed in a transparent reactor by a support to carry out the degradation reaction. Its plane is suspended in the waste water solution. The waste water solution is stirred under sunlight to achieve the purpose of degrading organic pollutants.

[0022] Furthermore, during the degradation process, the organic pollutants are antibiotics or dyes, with a concentration of 5-30 PPM. The antibiotic pollutant is at least one of ciprofloxacin (CIP) and levofloxacin (LVF), and the dye is at least one of methylene blue (MB) and methyl orange (MO). The stirring speed is 500-800 rpm, the carbon cloth and wire mesh remain basically still, and the light intensity is 2-4 times the solar intensity.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0024] ① The Co@MoS2 / carbon cloth composite piezoelectric catalyst prepared by this invention is more suitable for environmental use, and unlike powdered Co@MoS2, the Co@MoS2 material used is easy to fix and easy to recycle; the cobalt-doped molybdenum disulfide prepared by this invention grows and distributes evenly on carbon cloth, which has more feasible practical application and is better recyclable than cobalt-doped molybdenum disulfide powder that is not grown on carbon cloth.

[0025] ②The Co@MoS2 / carbon cloth composite piezoelectric catalyst prepared by this invention, as a whole, can also utilize the black and gray textile product of carbon cloth to utilize solar energy. For Co@MoS2, which is a semiconductor, it can also utilize its photocatalytic ability. If it is used as a composite catalyst, it is beneficial to better degrade and remove pollutants.

[0026] ③ Compared to the inherent problems of poor conductivity, inert basal surface, limited number of active sites, and easy aggregation of molybdenum disulfide (MoS2) as an active component, which lead to insufficient catalytic activity, the Co single-atom doping of this invention is beneficial to improve the overall catalytic ability of the material. The Co@MoS2 / carbon cloth composite piezoelectric catalyst prepared in this invention can efficiently treat pollutants and has a short processing time.

[0027] ④ In this invention, the overall preparation method of the catalyst is relatively simple, the synthesis requirements are low, and the operation is safer. Attached Figure Description

[0028] Figure 1 This is a comparison diagram of the original carbon cloth and the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1.

[0029] Figure 2 The image shows the EDS diagram of the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1.

[0030] Figure 3 The image shows a SEM comparison of the original carbon cloth and the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1. The left side shows the original carbon cloth, and the right side shows the Co@MoS2 / carbon cloth composite piezoelectric catalyst.

[0031] Figure 4The graph shows the degradation effect of the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1 under different concentrations of pollutants.

[0032] Figure 5 The graph shows the degradation effect of the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1 on pollutants in different pH environments.

[0033] Figure 6 The graph shows the pollutant degradation effect of Co@MoS2 / carbon cloth composite piezoelectric catalysts with different proportions.

[0034] Figure 7 The image shows the pollutant degradation effect of composite materials synthesized by doping with different metal single atoms. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0036] Example 1: Preparation of Co@MoS2 / carbon cloth composite piezoelectric catalyst

[0037] ① Weigh out 1.1638g of ammonium heptamolybdate (molecular formula (NH4)6Mo7O) 24 1.0657 g of molybdenum and 1.0657 g of thiourea were gradually dissolved in 30 mL of deionized water and heated and stirred in a water bath at room temperature for 1 h to obtain a homogeneous molybdenum / sulfur precursor solution. At the same time, a cobalt chloride solution with a concentration of 10 mM was prepared.

[0038] ② Cut the carbon cloth into 1cm×1.5cm pieces and gradually soak them in acetone, anhydrous ethanol and deionized water, and then sonicate them for 20 minutes each.

[0039] ③ The molybdenum / sulfur precursor solution from step ① and the carbon from step ② are arranged in a 50mL stainless steel reactor lined with polytetrafluoroethylene. After sealing the reactor, it is placed in an oven for hydrothermal reaction at a temperature of 200℃ for 24 hours.

[0040] ④ After the reaction is complete and the container has cooled, inject 10 mL of cobalt chloride solution into the inner liner and continue to place it in the oven for hydrothermal reaction. The reaction temperature is 180℃ and the reaction time is 3 hours.

[0041] ④ After the secondary hydrothermal reaction is completed, the sample is naturally cooled to room temperature. After taking out the sample, it is rinsed with ethanol and deionized water 3 to 5 times, then soaked in deionized water for 1 hour, and then dried in an oven at 50°C to obtain the Co@MoS2 / carbon cloth composite piezoelectric catalyst with a Mo:Co atomic molar ratio of 70:1.

[0042] Figure 1This is a before-and-after comparison image after the material preparation, specifically a comparison image of carbon cloth and the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1.

[0043] Figure 2 The images show the EDS spectra of the Co@MoS2 / carbon cloth composite piezoelectric catalyst. Figure 3 The image shows a comparison of SEM images of the original carbon cloth and the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1, indicating that MoS2 was successfully loaded onto the carbon cloth, and Co was also incorporated into the material.

[0044] Comparative Example 1: Preparation of MoS2 / carbon cloth composite piezoelectric catalyst

[0045] The preparation steps of the MoS2 / carbon cloth composite piezoelectric catalyst in Comparative Example 1 are similar to those in Example 1. The difference is that no cobalt source is added in Comparative Example 1 for a secondary hydrothermal reaction. The remaining steps are the same as in Example 1, and the MoS2 / carbon cloth composite piezoelectric catalyst is finally obtained.

[0046] Example 2: Experiment on the piezoelectric catalytic degradation of organic pollutants by Co@MoS2 / carbon cloth composite piezoelectric catalyst

[0047] Three pieces of the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1 were taken and fixed onto a pre-cut 4×4cm wire mesh. The wire mesh was fixed in a 250mL beaker using a support, with the entire plane of the wire mesh containing the Co@MoS2 / carbon cloth composite piezoelectric catalyst suspended inside the beaker. A rotor was placed at the bottom of the beaker, and the beaker was placed on a magnetic stirrer rotating at 700rpm (the wire mesh and the carbon cloth on it were fixed and did not move with the water flow). 60mL of prepared wastewater solutions were prepared and poured into the beaker. The mixture was allowed to stand for 5 minutes to allow for adsorption, and then the magnetic stirrer was turned on to initiate the piezoelectric catalytic degradation reaction. It should be noted that after the reaction begins, the carbon cloth will be transferred to a photoreactor and exposed to sunlight (at an intensity of 3 times the solar intensity).

[0048] During the reaction, samples were taken at intervals to detect and calculate the degradation effect.

[0049] Comparative Example 2

[0050] The experimental steps of Comparative Example 2 were repeated in Example 2, except that the Co@MoS2 / carbon cloth composite piezoelectric catalyst in Example 1 was replaced with the MoS2 / carbon cloth composite piezoelectric catalyst in Comparative Example 1. All other steps were the same as in Example 2.

[0051] Example 3

[0052] The degradation of ciprofloxacin CIP wastewater was carried out according to the method and steps of Example 2. Under conditions where the initial CIP concentrations were 10, 20, 30, and 40 mg / L, and the pH was adjusted to 5, the degradation effect of the Co@MoS2 / carbon cloth composite piezoelectric catalyst in environments with different pollutant concentrations was as follows: Figure 4 As shown. From Figure 4 It can be seen that when the initial concentration of CIP is 10 mg / L, the removal rate of CIP can reach more than 99% when the degradation time reaches 15 min.

[0053] Example 4

[0054] The ciprofloxacin (CIP) wastewater was degraded according to the method and steps in Example 2. The initial CIP concentration was 10 mg / L. The pH of the wastewater was adjusted to 1, 5, 7, and 11 using hydrochloric acid or NaOH solution, respectively. The degradation effect of the Co@MoS2 / carbon cloth composite piezoelectric catalyst on the pollutants at different pH values ​​is shown in the figure. Figure 5 .from Figure 5 It can be seen that the wastewater solution can achieve a good degradation effect when the pH is 5 or 7.

[0055] Example 5

[0056] In the synthesis of Co@MoS2 / carbon cloth composite piezoelectric catalysts according to the method of Example 1, the concentration of the cobalt chloride solution was adjusted to obtain Co@MoS2 / carbon cloth composite piezoelectric catalysts with different cobalt doping ratios (the method for different cobalt doping amounts is similar to that in Example 1, i.e., different concentrations of cobalt chloride solution are prepared in advance and a secondary hydrothermal reaction is carried out), thereby obtaining Co@MoS2 / carbon cloth composite piezoelectric catalysts with different Co doping amounts.

[0057] The ciprofloxacin (CIP) wastewater was degraded according to the method and steps in Example 2. The initial CIP concentration was 10 mg / L, and the pH of the wastewater was adjusted to 5. The degradation effect of the Co@MoS2 / carbon cloth composite piezoelectric catalyst on the pollutants under different Co doping levels is shown in the figure. Figure 6 As shown, it can be seen that a suitable amount is needed when doping with Co single atoms. As a single atom that provides or increases active sites, too much may cover the original active sites, while too little may not achieve the purpose of increasing the catalytic effect.

[0058] Comparative Example 3

[0059] When synthesizing single-atom doped composite materials, different metals are selected for doping, and the metal doping content is the same as in Example 1. Fe, Ni, and two metals co-doping such as Co / Fe are selected respectively. The specific process is as follows: when synthesizing Co@MoS2 / carbon cloth composite piezoelectric catalyst according to the method of Example 1, the 10mM cobalt chloride solution is replaced with ferric chloride solution, nickel chloride solution, or ferric chloride-cobalt chloride solution (iron and cobalt molar ratio 1:1) with a total doping metal content of 10mM. Composite piezoelectric catalysts with different metal single atoms doped can be obtained.

[0060] The ciprofloxacin (CIP) wastewater solution was degraded according to the method and steps of Example 2. The initial CIP concentration was 10 mg / L, and the pH of the wastewater solution was adjusted to 5. The degradation effect of the composite piezoelectric catalysts with different metal single-atom doping on the pollutants is shown in the figure. Figure 7 As shown, Figure 7 In the middle, None indicates the MoS2 / carbon cloth composite piezoelectric catalyst in Comparative Example 1. Figure 7 In this context, Co represents the Co@MoS2 / carbon cloth composite piezoelectric catalyst obtained in Example 1. From... Figure 7 It can be seen that the improvement effect of single Co doping is better than that of other single-atom metal doping.

[0061] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. An application of a Co@MoS2 / carbon cloth composite piezoelectric catalyst in the piezoelectric-photocatalytic degradation of organic pollutants in wastewater, characterized in that, Preparation method of Co@MoS2 / carbon cloth composite piezoelectric catalyst Includes the following steps; 1) The molybdenum source and sulfur source are gradually added to deionized water and stirred in a water bath to dissolve them, thus obtaining a molybdenum / sulfur precursor solution for later use; Dissolve the cobalt source in deionized water to obtain a cobalt source solution for later use. 2) After cleaning and pretreatment of the carbon cloth, it is transferred into the reactor together with the molybdenum / sulfur precursor solution prepared in step 1) for a first hydrothermal reaction. After the reaction is completed, the cobalt source solution prepared in step 1) is added to the reaction solution to continue the second hydrothermal reaction. After the reaction is completed and cooled, the obtained carbon cloth is cleaned and dried to obtain the Co@MoS2 / carbon cloth composite piezoelectric catalyst. The molar ratio of the molybdenum source and the sulfur source in step 1) is 1:2-6, and the molar ratio of Co in the cobalt source to Mo in the molybdenum source is 1:70-80. In step 2), the temperature of the secondary hydrothermal reaction is 160~200℃, and the reaction time is 2~4 hours.

2. The application as described in claim 1, characterized in that, The molybdenum source mentioned in step 1) is ammonium heptamolybdate, and the sulfur source is thiourea. The temperature at which the molybdenum source and the sulfur source are added to deionized water and stirred to dissolve is 40-60℃, and the stirring and dissolving time is 15-30 minutes, to ensure that both the molybdenum source and the sulfur source can be dissolved.

3. The application as described in claim 1, characterized in that, The molar ratio of the molybdenum source and the sulfur source mentioned in step 1) is 1:4~4.

5.

4. The application as described in claim 1, characterized in that, The cobalt source mentioned in step 1) is cobalt chloride.

5. The application as described in claim 1, characterized in that, In step 2), the carbon cloth is pre-treated by cleaning. The carbon cloth is placed in acetone, anhydrous ethanol and deionized water for ultrasonic treatment, and the ultrasonic treatment time is 5 to 30 minutes.

6. The application as described in claim 1, characterized in that, In step 2), the temperature of the hydrothermal reaction is 180~220℃, and the reaction time is 20~30 hours.

7. The application as described in claim 1, characterized in that... In step 2), the Co@MoS2 / carbon cloth composite piezoelectric catalyst prepared had a Co@MoS2 loading of 3.0–5.0 mg / cm³ on the carbon cloth. 2 .

8. The application as described in claim 1, characterized in that, The application method includes the following steps: ① Use wire mesh to fix the Co@MoS2 / carbon cloth composite piezoelectric catalyst; ② The wire mesh with Co@MoS2 / carbon cloth composite piezoelectric catalyst is fixed in a transparent reactor by a support to carry out the degradation reaction. Its plane is suspended in the waste water solution. The waste water solution is stirred under sunlight to achieve the purpose of degrading organic pollutants.

9. The application as described in claim 8, characterized in that... The organic pollutant is an antibiotic or dye, with a concentration of 5-30 PPM. The antibiotic pollutant is at least one of ciprofloxacin (CIP) and levofloxacin (LVF), and the dye is at least one of methylene blue (MB) and methyl orange (MO). The stirring speed is 500-800 rpm, and the light intensity is 2-4 solar irradiances.

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