Preparation of Cd(II) loaded imprinted polymer coated on CdS nanorods and application thereof

Abstract

The application belongs to the field of semiconductor photocatalysis, and particularly relates to preparation and application of a kind of Cd(II) load imprint polymer coated on CdS nanorod. The application is to use CdS as polymer carrier, and adopt bulk thermal polymerization method to coat Cd(II) load imprint polymer on the surface of CdS nanorod, to prepare the imprint polymer coated on CdS nanorod. The application constructs Cd(II) load imprint polymer protective layer on the surface of CdS catalyst, to inhibit the photo-corrosion of CdS. Cd(II)-IIP coated on CdS is like a layer of "armor", to support the structural collapse of CdS structure caused by photo-corrosion, and to prevent the direct contact of surrounding oxygen and H2O medium. The photo-corrosion resistance of CdS is improved, and the charge separation efficiency of catalyst is slightly enhanced.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor photocatalysis, specifically relating to the preparation and application of a Cd(II)-loaded imprinted polymer coated on CdS nanorods. Background Technology

[0002] Currently, rapid urbanization and industrialization have led to a continuous increase in energy demand and excessive consumption of traditional fossil fuels, resulting in increased pollution of the natural environment and a severe global energy shortage. Therefore, there is an urgent need to find a scientific technology to produce sustainable, clean, and green energy to address the global energy and environmental crisis caused by excessive energy consumption. Among various technological research projects, stable solar-driven integrated water separation for hydrogen production is a very promising approach to achieving a clean and renewable energy supply in the future. Hydrogen energy, as one of the cleanest and most environmentally friendly energy sources and a substitute for fossil fuels, has become a global research hotspot and is considered a potential candidate for future energy supply. It offers an effective solution to the world's ever-growing energy demand and environmental problems, and has therefore received widespread attention.

[0003] In semiconductors used for hydrogen production, CdS, a typical n-type semiconductor with a band gap of 2.4 eV, is considered a highly visible-light-responsive material for photocatalytic hydrogen production. Unfortunately, severe photocorrosion and rapid recombination of photogenerated electrons and holes in CdS limit its widespread application in photocatalysis research, and CdS photocatalytic hydrogen production still faces many challenges. There are two pathways of photocorrosion in CdS. One is called direct photocorrosion, also known as self-corrosion, where surface sulfur ions are oxidized to elemental sulfur and SO4 by the strong oxidizing power of photogenerated holes. 2- Another type is indirect photocorrosion, in which the surrounding medium, such as oxygen and H2O, interacts with photogenerated electrons / holes, leading to the dissolution of metal sulfides. Due to photocorrosion, its stability as a photocatalyst is poor. Therefore, solving the photocorrosion of CdS and improving its separation efficiency of photogenerated electron pairs are the main tasks to improve its photocatalytic performance in order to achieve efficient overall water separation for hydrogen production.

[0004] Ion imprinting technology is a kind of polymer adsorbent formed by crosslinking agent, functional monomer and template ions such as Cd(II), Hg(II), Cr(VI), Co(II), Cu(II) and the like. In the process of synthesizing ion imprinting polymer, template ions interact with selected functional monomers to form a main-guest complex. Then, the crosslinking agent is added to the obtained high polymer. When the template ions are removed, a large number of artificial recognition sites of target ions are generated, which are complementary to the target ions in shape, size and functional groups. Therefore, ion imprinting polymer materials are used to remove pollutant target ions in wastewater due to their good adsorption capacity and recognition ability. So far, many studies on loading IIP on photocatalysts to enhance the photocatalytic performance have been reported. So far, there are few reports on imprinting polymers wrapped on CdS, especially for the study of photocatalytic hydrogen evolution stability and the study of reducing photocorrosion using the same. SUMMARY

[0005] To solve the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a preparation method of Cd(II) loaded imprinting polymer coated on CdS nanorods. The present application uses CdS as a polymer carrier and adopts the method of bulk thermal polymerization to coat Cd(II) loaded imprinting polymer on the surface of CdS nanorods.

[0006] Another purpose of the present application is to provide a Cd(II) loaded imprinting polymer coated on CdS nanorods prepared by the above method.

[0007] Still another purpose of the present application is to provide the application of the above Cd(II) loaded imprinting polymer coated on CdS nanorods as a photocatalyst.

[0008] The purposes of the present application are achieved by the following technical solutions:

[0009] A preparation method of Cd(II) loaded imprinting polymer coated on CdS nanorods, comprising the following steps:

[0010] (1) First, disperse CdS (cadmium sulfide) nanorods in an organic solvent and ultrasonically treat at room temperature to obtain a dispersion solution marked as solution A; then, dissolve CdCl2.2.5H2O in a mixed solution of organic solvent and water, and then add functional monomer 4-vinylpyridine to perform pre-polymerization under stirring condition. After the reaction, add crosslinking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile to obtain a solution marked as solution B;

[0011] (2) After mixing solution A and solution B, heat to polymerize, collect the precipitate by centrifugation after the polymerization, wash and dry to obtain the final product.

[0012] Preferably, the organic solvent in step (1) is at least one of acetone, methanol and acetonitrile, the crosslinking agent is ethylene glycol dimethacrylate or tetraethoxysilane, and the initiator is azobisisobutyronitrile.

[0013] Preferably, in step (1), the amount ratio of CdS, CdCl2·2.5H2O, 4-vinylpyridine, crosslinking agent and initiator is 0.2g:0.009-0.037g:0.1875-0.75mL:0.237-0.95mL:0.02-0.08g.

[0014] More preferably, the amount ratio of CdS, CdCl2·2.5H2O, 4-vinylpyridine, crosslinking agent and initiator is 0.2g:0.0185g:0.375mL:0.475mL:0.04g.

[0015] More preferably, the amount ratio of CdS and organic solvent in solution A is 0.2g:30mL; and the amount ratio of CdCl2·2.5H2O and the mixed solution of organic solvent and water in solution B is 0.009-0.037g:50mL.

[0016] Preferably, the stirring speed in step (1) is 600rpm during the pre-polymerization, and the reaction time is 1h.

[0017] Preferably, the ultrasonic treatment time in step (1) is 10min.

[0018] Preferably, in step (1), the CdS nanorods are synthesized by one-step hydrothermal method: Cd(NO3)2·4H2O is added to ethylenediamine, and after the complete dissolution of Cd(NO3)2·4H2O, thiourea is added and stirred until dissolved; the mixed solution is transferred to a high-pressure reaction kettle for hydrothermal reaction, and the obtained product after reaction is washed and dried to obtain yellow powder, which is CdS nanorods.

[0019] More preferably, the amount of Cd(NO3)2·4H2O is 3.853 parts by mass, the amount of thiourea is 2.853 parts by mass, and the amount of ethylenediamine is 60 parts by volume.

[0020] More preferably, the temperature of the hydrothermal reaction is 160℃, and the reaction time is 24h.

[0021] Preferably, the temperature of the polymerization reaction in step (2) is 60-80℃, more preferably 70℃; the polymerization reaction time is 2-12h, more preferably 4h.

[0022] Preferably, the centrifugal speed in step (2) is 8000-10000rpm, and the time is 5min.

[0023] Preferably, the drying in the present application is all vacuum drying, the temperature of the vacuum drying is all 50-60℃, and the drying time is all 12-24h.

[0024] The Cd(II) loaded imprinting polymer coated on the CdS nanorod provided by the present application can be used as a photocatalyst, and shows good potential application in the field of energy photocatalysis under visible light, and can be applied to photocatalytic overall water splitting.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] 1. The Cd(II) loaded imprinting polymer coated on the CdS nanorod provided by the present application, with the protection of the imprinting polymer shell, prevents the direct contact of CdS with H2O and O2, thus preventing the Cd 2+ dissolved in water molecules and S 2- oxidation, has better photocatalytic stability and better anti-photo corrosion performance.

[0027] 2. The preparation method of the present application is simple, and simple heating polymerization can provide a simple and new strategy for surface regulation of other easily photo-corrosion semiconductor photocatalyst nanomaterials.

[0028] 3. The present application regulates the surface of CdS, and the Cd(II) loaded imprinting polymer coated on the CdS nanorod (denoted as CdS@Cd(II)-IIP) prepared under visible light has good photocatalytic stability. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 SEM spectra of samples prepared in Examples 1-3 and CdS, wherein a is the morphology of CdS@Cd(II)-IIP prepared in Example 2; b is the SEM morphology of CdS@Cd(II)-IIP prepared in Example 1; c is the SEM morphology of CdS@Cd(II)-IIP prepared in Example 3; d is the SEM morphology of CdS.

[0030] Figure 2 XRD spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1.

[0031] Figure 3 The FT-IR spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 are shown.

[0032] Figure 4 The images show the SEM, TEM, and EDS spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1. (a) and (c) are morphology images of CdS, (b), (d), and (e) are morphology images of CdS@Cd(II)-IIP-Cu(II); (f) depicts the HAADF-STEM and corresponding STEM-EDS elemental mapping images of CdS@Cd(II)-IIP-Cu(II).

[0033] Figure 5 XPS full spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1.

[0034] Figure 6 The photoluminescence (PL) spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1.

[0035] Figure 7 The photocatalytic hydrogen production performance of CdS and CdS@Cd(II)-IIP prepared in Example 1 is shown in the figure.

[0036] Figure 8 Potassium permanganate titration method for detecting H2O2 in reaction solution.

[0037] Figure 9 The graph shows the photocatalytic hydrogen peroxide production performance of CdS@Cd(II)-IIP prepared in Example 1.

[0038] Figure 10 The concentration of cadmium ions in the reaction solution of CdS and CdS@Cd(II)-IIP prepared in Example 1 changes with light exposure time.

[0039] Figure 11 The images show the SEM and TEM spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 before and after 80 h of reaction; (a) SEM spectrum of CdS before reaction, (b) SEM spectrum of CdS after reaction, (c) SEM spectrum of CdS@Cd(II)-IIP before reaction, (d) SEM spectrum of CdS@Cd(II)-IIP after reaction, (e) TEM spectrum of CdS after reaction, and (f) and (g) TEM spectra of CdS@Cd(II)-IIP after reaction. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be referred to.

[0041] Evaluation of photocatalytic hydrogen production activity: Throughout the experiment, a LabSolar 6A photocatalytic hydrogen evolution system and an Agilent 8860 gas chromatograph were used. 50 mg of photocatalyst was dispersed in 100 mL of deionized water and loaded with 3 wt% Pt. After ultrasonic dispersion for 15 min, 100 mL of the solution was transferred to a sealed-top irradiation negative pressure reactor made of quartz. A 300 W xenon lamp was used as the light source, and visible light was obtained through an AM1.5 filter. The LabSolar 6A photocatalytic hydrogen evolution system was evacuated for 30 min to create an anaerobic environment before illumination. Prolonged illumination was performed, and the photocatalytic hydrogen evolution yield was measured.

[0042] H2O2 determination by KMnO4 titration: According to literature, H2O2 was quantitatively detected by titration after 10 h of photocatalytic reaction. Specifically, 1.7 μmol / mL KMnO4 was used. -1 A KMnO4 solution was used as the titrant because the deep purple KMnO4 has a strong oxidizing ability and can be reduced by H2O2 to produce colorless MnO4 in an acidic environment. 2+ (MnSO4) product. The corresponding reaction formula is shown below.

[0043] 2KMnO4+5H2O2+3H2SO4→K2SO4+2MnSO4+8H2O+5O2

[0044] During the titration process, the concentrated sulfuric acid was first diluted with deionized water (concentrated sulfuric acid / water volume ratio = 1:5), and then 10 ml of the diluted sulfuric acid was added to a 50 ml beaker. The supernatant of the photocatalytic reaction after centrifugation (containing a certain amount of H2O2, 10 ml) was poured into the same beaker under vigorous stirring.

[0045] Determination of CdS photocorrosion: The change in cadmium ion concentration in the reaction solution with light exposure time was tested using an inductively coupled plasma optical emission spectrometer (ICP) on an Agilent 725-ES device.

[0046] Example 1

[0047] The preparation of a Cd(II)-loaded imprinted polymer coated on CdS nanorods includes the following steps:

[0048] (1) Preparation of CdS nanorods: 3.853 g of cadmium nitrate tetrahydrate (Cd(NO3)2·4H2O) was dissolved in 60 mL of ethylenediamine. After the cadmium nitrate was completely dissolved, 2.853 g of thiourea was added and stirred until dissolved. The mixed solution was placed in a 100 mL polytetrafluoroethylene high-pressure reactor liner and heated at 160 °C for 24 h. After removing the reactor, it was naturally cooled to room temperature. The yellow precipitate was collected and carefully washed five times each with distilled water and anhydrous ethanol. Finally, it was dried in a vacuum oven at 60 °C to obtain CdS powder.

[0049] (2) 200 mg CdS powder was ultrasonically dispersed in 30 mL of acetone solution to obtain solution A; CdCl2·2.5H2O and 4-vinylpyridine (4-VP) were added to a mixture of 30 mL of acetone and 20 mL of deionized water and stirred at 600 rpm for 1 h. A certain amount of ethylene glycol dimethacrylate (EGDMA) and azobisisobutyronitrile (AIBN) were added in sequence and stirred evenly to obtain solution B.

[0050] In solution B, the ratio of CdCl2·2.5H2O, acetone, water, 4-vinylpyridine, ethylene glycol dimethacrylate, and azobisisobutyronitrile is 0.0185g:30mL:20mL:0.375mL:0.475mL:0.04g.

[0051] (3) Mix solutions A and B thoroughly, transfer the mixture to a sealed blue-capped bottle, and polymerize in an oil bath at 70°C for 4 hours. Finally, wash the product three times with ethanol / water (70 / 30, V / V) to ensure the removal of unreacted monomers and other components. Then centrifuge and vacuum dry at 60°C for 24 hours. The collected product is the Cd(II)-loaded imprinted polymer coated on CdS nanorods, named CdS@Cd(II)-IIP.

[0052] Example 2

[0053] In this embodiment, the imprinted polymer loaded with Cd(II) on CdS nanorods was prepared according to the steps of Example 1. Except that the ratio of CdCl2·2.5H2O, acetone, water, 4-vinylpyridine, ethylene glycol dimethacrylate and azobisisobutyronitrile in solution B in step (2) was 0.0009g:30mL:20mL:0.1875mL:0.2375mL:0.02g, the other parameters and conditions were the same as in Example 1.

[0054] Example 3

[0055] In this embodiment, the imprinted polymer loaded with Cd(II) on CdS nanorods was prepared according to the steps of Example 1. Except that the ratio of CdCl2·2.5H2O, acetone, water, 4-vinylpyridine, ethylene glycol dimethacrylate and azobisisobutyronitrile in solution B in step (2) was 0.037g:30mL:20mL:0.75mL:0.95mL:0.08g, the other parameters and conditions were the same as in Example 1.

[0056] Figure 1 These are morphological images from the process of optimizing the imprinted shell and CdS ratio in Examples 1-3. Figure 1 (a) shows that an excessively thick imprinted shell affects the nanorod structure of CdS, leading to morphological collapse of CdS; from Figure 1 As shown in (b), the morphology of CdS in CdS@Cd(II)-IIP does not change during the polymerization reaction, but it can be seen that a layer of material is coated on its outer surface, resulting in a rough surface, indicating that the coating is successful. Figure 1 As shown in (c), the morphology is the same as that of CdS. This may be because the content of functional monomers, crosslinking agents and initiators is low during the synthesis process, which leads to the failure of the polymerization reaction. Therefore, after optimization, the optimal ratio of raw materials was confirmed to be the ratio described in Example 1.

[0057] Figure 2 The XRD patterns of CdS and CdS@Cd(II)-IIP prepared in Example 1 are shown in the figures. As can be seen, both CdS and CdS@Cd(II)-IIP materials exhibit sharp diffraction peaks at the same location, both identified as hexagonal wurtzite, possessing a good crystal structure, consistent with standard card PDF#41-1049. This indicates that the crystal structure of CdS remained unchanged during the preparation of CdS@Cd(II)-IIP using CdS nanorods, but its diffraction peak intensity was slightly lower than that of CdS. This phenomenon suggests that the polymerization process weakens the diffraction peaks of CdS by the encapsulated polymer.

[0058] Figure 3 The FT-IR spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 are shown in the figure. It can be seen from the figure that after the CdS was imprinted, a new absorption peak was added to CdS. (1724 cm⁻¹) -1 and 2920cm -1 The strong characteristic peak at 1415 cm⁻¹ may correspond to C=O and CH, which belong to the characteristic band of EGDMA. -1 and 1600cm -1 The specific peaks at 1149 cm⁻¹ can be assigned to CN and C=N, which are attributed to the characteristic tensile vibrations of the pyridine ring in 4-VP. -1The unique peaks at these locations are attributed to the stretching vibrations of CN in the initiator AIBN. These bands confirm the successful occurrence of bulk polymerization, indicating that the Cd ion-loaded imprinted polymer is coated on the surface of CdS.

[0059] Figure 4 The SEM, TEM, and EDS spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 are shown. As can be seen from the figures, CdS and CdS@Cd(II)-IIP have similar morphologies. The morphology of CdS in CdS@Cd(II)-IIP does not change during the imprinting process, but it is evident that a layer of material is coated on its outer surface. EDS elemental analysis shows that the C, N, and O contents in CdS@Cd(II)-IIP are increased compared to CdS, indicating the presence of an imprinted polymer. This is further demonstrated in the TEM images. A continuous and uniform organic layer exists on the surface of CdS@Cd(II)-IIP, used to encapsulate CdS to form a core-shell structure. Combined with FT-IR results, it is clear that 4-VP can effectively polymerize to form a polymer and uniformly cover the surface of the CdS nanorods.

[0060] Figure 5 The high-resolution XPS spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 are shown in the figures. It can be seen that the O element on the surface of CdS@Cd(II)-IIP mainly exists in EGDMA during the synthesis process. The binding energy peak at 533.3 eV is attributed to the C=O bond, and the binding energy peak at 531.8 eV is attributed to the C–O bond. Meanwhile, in the high-resolution C1s spectrum, the binding energy at 288.7 eV is attributed to the C=N bond in the pyridine group and the C=O bond in EGDMA, the binding energy at 286.5 eV is attributed to the CN bond in 4-VP or EGDMA and the CO bond in EGDMA, and the peak at 284.80 eV corresponds to the C-C bond, CH bond, and C=C bond in the imprinted layer. The binding energy at 286.5 eV in CdS@Cd(II)-IIP is the CN bond formed in the synthetic imprinted shell. No N element was detected in CdS. The preliminary results indicate that the imprinted polymer layer was successfully prepared. The binding energies of CdS at 411.6 eV and 404.92 eV belong to Cd 3d 3 / 2 and Cd 3d 5 / 2, respectively, while the binding energies of S2p 1 / 2 and S2p 3 / 2 are 162.5 eV and 161.3 eV, respectively. The XPS spectrum of unreacted CdS@Cd(II)-IIP is similar to that of CdS, but it shifts overall to positions with lower binding energies, by about 0.3 eV. Furthermore, the characteristic peak intensities of Cd 3d and S2p are lower than those of CdS. This may be due to the weakening of CdS X-ray excitation caused by the imprinted polymer layer, indirectly indicating that the Cd(II)-loaded imprinted polymer shell is on the surface of CdS.

[0061] Figure 6 The photoluminescence (PL) spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 help reveal the capture, migration, transfer, separation, and recombination efficiency of photogenerated carriers, which are the most critical factors determining the photocatalytic performance of semiconductor-based materials. The PL emission spectra of CdS NRs and CdS@Cd(II)-IIP catalysts excited at 353 nm at room temperature showed that CdS and CdS@Cd(II)-IIP exhibited a photoluminescence peak at around 470 nm. Compared with CdS NRs, the fluorescence intensity of CdS@Cd(II)-IIP was significantly reduced, indicating that the recombination of photogenerated electrons and holes was suppressed.

[0062] Figure 7 The CdS and CdS@Cd(II)-IIP nanorods prepared in Example 1, loaded with 3% Pt, were subjected to visible light photocatalytic hydrogen evolution stability tests in a pure water system. After 15 h of visible light irradiation, the rate of increase in hydrogen production from the CdS nanorods gradually slowed down, and the H2 evolution rate also gradually decreased. The hydrogen production was approximately 1046.26 μmol / g at 15 h and approximately 1387.87 μmol / g after 80 h. The hydrogen evolution rate at 80 h increased by only 32.65% compared to the first 15 h, and the slowing down of hydrogen production is attributed to photocorrosion and the rapid recombination of photogenerated electrons and holes. The hydrogen evolution rate of CdS@Cd(II)-IIP continued to increase steadily after 15 h, indicating that the appropriately thick imprinted shell not only enhances the separation of photoelectrons and holes but also inhibits the photocorrosion of CdS. The photocatalytic hydrogen evolution performance of CdS@Cd(II)-IIP in the first 15 h was basically the same as that of pure CdS nanorods, at approximately 988.81 μmol / g. After 80 h, the total hydrogen evolution was approximately 2721.30 μmol / g, an increase of approximately 175.21% compared to the 15 h result. These results indicate that the imprinted shell does not significantly enhance the photocatalytic activity of CdS. This may be because the imprinted shell is a polymer and lacks semiconductor activity; therefore, its combination with CdS did not improve its photocatalytic hydrogen evolution performance. However, the protective effect of the appropriately thick imprinted polymer shell inhibited the photocorrosion of CdS, thereby improving its photocatalytic hydrogen evolution stability.

[0063] Figure 8 , Figure 9 This study aimed to perform a simple qualitative and quantitative analysis of H₂O₂ in the photocatalytic reaction. In this reaction system, no sacrificial agent was added; only 3% Pt was loaded as a co-catalyst. However, O₂ was not detected in the gas phase test, indicating the presence of other water oxidation intermediates or products. The possibility that H₂O₂ replaced O₂ as an oxidation product in the 20-hour photocatalytic reaction was qualitatively analyzed using KMnO₄ titration. Purple KMnO₄ was used as the titrant, and its decolorization reaction originated from H₂O₂ reduction. The titration endpoint could be traced by a pink color lasting more than 30 seconds. Figure 9Based on the qualitative analysis of the presence of H2O2 using the KMnO4 decolorization reaction, the amount of titrant (KMnO4) used can also be used to roughly estimate the concentration and corresponding molar number of H2O2 in the CdS and CdS@Cd(II)-IIP reaction solutions. Figure 8 As shown, the H2 / H2O2 molar ratio did not reach 1:1 because some oxygen was produced. However, due to the low oxygen production, the detection accuracy of the gas phase was insufficient, making it impossible to detect the produced O2. Furthermore, the hydrogen peroxide was easily decomposed, resulting in the inability to accurately measure the hydrogen peroxide production.

[0064] Figure 10 This is a schematic diagram showing the change in Cd(II) concentration over time in the CdS and CdS@Cd(II)-IIP photocatalytic reaction solutions prepared in Example 1. To clarify the degree of photocorrosion of the photocatalyst during the reaction process, the reaction was carried out continuously for 30 hours, with samples taken every 5 hours to measure the Cd concentration in the solution. 2+ ICP analysis was performed on the concentration, and due to the presence of uneluted Cd in the blot layer, the concentration was found to be low. 2+ Cd in the initial CdS@Cd(II)-IIP solution 2+ The concentration of CdS was greater than that of CdS. However, after several cycles of reaction, the concentration of CdS in the dispersion solution of the CdS@Cd(II)-IIP catalyst was lower than that of CdS. 2+ The concentration was much lower than that of CdS. These results confirm that the imprinted shell can greatly improve the photoreactivity stability of CdS. These results are in good agreement with the photocatalytic performance of CdS@Cd(II)-IIP, indicating that CdS@Cd(II)-IIP has good resistance to photocorrosion.

[0065] Figure 11 The SEM and TEM spectra of CdS and CdS@Cd(II)-IIP prepared in Example 1 before and after the reaction are shown. The sample was recovered after 80 h of reaction, and SEM and TEM tests were performed to compare its morphology and changes before and after the reaction. Figure 11 Images (a) and (b) in the figure can reflect the changes in the morphology and structure of CdS before and after 80 hours. Figure 11 In (b), it is clear that the CdS surface becomes passivated after 80 hours of reaction. Figure 11 In (e), the collapse of the nanorod structure can be seen more clearly using TEM. The difference is... Figure 11Images (c) and (d) show the morphological changes of the CdS@Cd(II)-IIP sample after being coated with the imprinted shell before and after 80 hours of reaction. Images (f) and (g) clearly show, through TEM, that the imprinted shell has a similar morphological structure to the unreacted CdS@Cd(II)-IIP, with the nanorod structure remaining intact and the boundaries clear. This indicates that the imprinted shell coating the CdS surface can firmly adhere to the CdS surface, effectively suppressing structural collapse caused by photocorrosion. Therefore, the imprinted shell aggregates on the CdS surface, acting like a protective shell that both supports the two-dimensional structure of the CdS nanorods and prevents direct contact with the surrounding medium (O2 and H2O), thus inhibiting the photocorrosion of CdS.

[0066] The above results indicate that coating the CdS surface with an imprinted shell is a feasible solution to effectively reduce photocorrosion and improve the stability of CdS photocatalytic hydrogen evolution.

[0067] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a Cd(II)-loaded imprinted polymer coated on CdS nanorods, characterized in that, Includes the following steps: (1) First, CdS nanorods were dispersed in an organic solvent and ultrasonically treated at room temperature to obtain a dispersion labeled as solution A; then, CdCl2·2.5H2O was dissolved in a mixed solution of organic solvent and water, and the functional monomer 4-vinylpyridine was added. A prepolymerization reaction was carried out under stirring conditions. After the reaction, the crosslinking agent ethylene glycol dimethacrylate and the initiator azobisisobutyronitrile were added to obtain a solution labeled as solution B. (2) Mix solutions A and B and heat to polymerize. After the polymerization reaction, collect the precipitate by centrifugation, wash and dry it to obtain the final product, which is the imprinted polymer loaded with Cd(II) on CdS nanorods.

2. The preparation method according to claim 1, characterized in that, The organic solvent mentioned in step (1) is at least one of acetone, methanol, and acetonitrile.

3. The preparation method according to claim 1, characterized in that, In step (1), the ratio of CdS, CdCl2·2.5H2O, 4-vinylpyridine, crosslinking agent and initiator is 0.2g: 0.009~0.037g: 0.1875~0.75mL: 0.237~0.95mL: 0.02~0.08g.

4. The preparation method according to claim 3, characterized in that, The ratio of CdS, CdCl2·2.5H2O, 4-vinylpyridine, crosslinking agent and initiator is 0.2g:0.0185g:0.375mL:0.475mL:0.04g.

5. The preparation method according to claim 1, characterized in that, The CdS nanorods described in step (1) are synthesized by a one-step hydrothermal method: Cd(NO3)2·4H2O is added to ethylenediamine, and after Cd(NO3)2·4H2O is completely dissolved, thiourea is added and stirred until dissolved; the mixed solution is transferred to a high-pressure reactor for hydrothermal reaction, and the product obtained after the reaction is washed and dried to obtain a yellow powder, which is the CdS nanorod.

6. The preparation method according to claim 5, characterized in that, The ratio of Cd(NO3)2·4H2O, thiourea, and ethylenediamine is 3.853g: 2.853g: 60mL; The hydrothermal reaction was carried out at a temperature of 160°C for 24 hours.

7. The preparation method according to claim 1, characterized in that, The polymerization reaction in step (2) is carried out at a temperature of 60-80℃ for 2-12 hours.

8. The preparation method according to claim 1, characterized in that, The centrifugation speed in step (2) is 8000-10000 rpm and the time is 5 min.

9. An imprinted polymer on CdS nanorods coated with Cd(II) loading, prepared by the method of any one of claims 1-8.

10. The application of the Cd(II)-loaded imprinted polymer coated on CdS nanorods as described in claim 9 as a photocatalyst.

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