Chiral porous alloy nanoparticles and preparation method thereof based on electric replacement reaction

Abstract

The invention provides chiral porous alloy nanoparticles and a preparation method thereof based on an electric replacement reaction. The preparation method comprises the following steps: preparing CNPs which is composed of Cu or Ag and has inherent structure chirality as a sacrificial template by adopting a glancing angle deposition method; and the sacrificial template is placed in an electrolyte containing ions of the metal A to be stirred, an electric replacement reaction is conducted for 1 h or above, and the Cu < 1-x > Ax or Ag < 1-x > Ax chiral porous alloy nanoparticles are obtained. According to the technical scheme, transferring of chirality from a sacrifice template to newly-generated nano-particles is achieved, a new way is provided for preparation of chiral nano-materials, the synthesis method and the application range of the chiral materials are expanded, and the obtained binary alloy nano-particles not only have a porous structure with an enhanced specific surface area, but also have a good application prospect. Moreover, the compound has unique chiral optical activity, and has potential application value in the fields of asymmetric catalysis, enantiomer distinguishing, enantiomer separation, biological detection, biological imaging and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanomaterials, and particularly relates to a chiral porous alloy nanoparticle and a preparation method thereof based on an electrochemical displacement reaction. BACKGROUND

[0002] Chiral nanoparticles have important application value in the fields of asymmetric catalysis, biological detection, etc. In the prior art, the preparation of chiral nanoparticles depends on chiral ligand induction or complex photolithography process, and there are problems of complex process, high cost, and difficulty in regulating material composition and morphology. In addition, although the traditional electrochemical displacement reaction (GRR) can be used to synthesize alloy nanoparticles, its application in chiral transfer has not been clarified, so that the generated porous alloy nanoparticles lack inherent chiral structure, which limits the application range. Therefore, it is urgent to develop a technical solution capable of efficiently transferring chirality and flexibly regulating material composition and morphology. SUMMARY

[0003] In view of the above technical problems, the present application discloses a chiral porous alloy nanoparticle and a preparation method thereof based on an electrochemical displacement reaction, which realizes efficient transfer of chirality from a template to a product, and the composition and pore structure of the porous alloy nanoparticle are controllable, thereby expanding the application of chiral nanomaterials in the fields of asymmetric catalysis, enantiomer differentiation, enantiomer separation, biological detection, and biological imaging, etc.

[0004] To this end, the technical solution adopted by the present application is as follows: A preparation method of a chiral porous alloy nanoparticle based on an electrochemical displacement reaction, comprising the following steps: Step S1, using a glancing angle deposition method to prepare CNPs composed of Cu or Ag as a sacrificial template with inherent structural chirality; Step S2, stirring the sacrificial template in an electrolyte containing ions of metal A, and performing an electrochemical displacement reaction for more than 1h to obtain Cu 1-x A x or Ag 1-x A x chiral porous alloy nanoparticles. In the formula, the metal A is Ag, Au, Pt, or Pd, and 0≤x≤1.

[0005] By using this technical solution, the transfer of chirality from the sacrificial template to the newly generated nanoparticles is realized through the electrochemical displacement reaction, which provides a new way for the preparation of chiral nanomaterials and expands the synthesis method and application range of chiral materials.

[0006] As a further improvement of the present application, the chiral porous alloy nanoparticle comprises Cu1-x Ag x , Ag 1-x Au x , Ag 1-x Pt x or Ag 1-x Pd x It exhibits a solid or mesoporous morphology and retains the chiral characteristics of the sacrificial template, with detectable circular dichroism signals.

[0007] preparation Cu 1-x Ag x middle, x The range of values ​​is determined by the conditions of the electrodisplacement reaction; changes in conditions such as reaction time and reactant concentration will affect the value. x The alloy composition can be controlled by altering it within a certain range. (Preparation of the...) Ag 1-x Au x , Ag 1-x Pt x and Ag 1- x Pd x middle, x The range of values ​​is affected by factors such as the concentration of metal ions in the reaction and the reaction time, and these alloy chiral nanoparticles exhibit a mesoporous morphology.

[0008] As a further improvement of the present invention, in step S1, grazing angle deposition technology is used to prepare nanoparticles with inherent chirality composed of Cu or Ag as sacrificial templates by rapidly rotating the substrate.

[0009] As a further improvement of the present invention, the height of the sacrificial template is 50-200 nm, the helical pitch P of the CNPs with inherent chirality composed of Cu is 20-30 nm, and the helical pitch of the CNPs with inherent chirality composed of Ag is 5-15 nm.

[0010] As a further improvement of the present invention, the height of Cu sacrificial template nanoparticles is 150~200nm, and the height of Ag sacrificial template nanoparticles is 50~150nm.

[0011] As a further improvement of the present application, the helical pitch P of the CNPs with inherent structural chirality composed of Cu is 25 nm, and the helical pitch of the CNPs with inherent structural chirality composed of Ag is 10 nm.

[0012] As a further improvement of the present application, in step S2, the time of the galvanic displacement reaction is 1h-7h.

[0013] As a further improvement of the present application, in step S2, the stirring rate is 350-450rpm.

[0014] As a further improvement of the present application, in the electrolyte, the concentration of the ions containing the metal A is 10-30μmol / L.

[0015] As a further improvement of the present application, the ions containing the metal A are Ag + , AuCl 4 - , PtCl 4 2- or PdCl 4 2- .

[0016] As a further improvement of the present application, when the chiral porous alloy nanoparticles are prepared Cu 1-x Ag x , the electrolyte is an aqueous solution containing AgNO 3 with a concentration of 20μmol / L, and the reaction is carried out at room temperature with a stirring rate of 380rpm; when the chiral porous alloy nanoparticles are prepared Ag 1-x Au x , the electrolyte is a saturated NaCl solution containing 20μmol / L HAuCl 4 .

[0017] The present application also discloses chiral porous alloy nanoparticles based on galvanic displacement reaction, which are prepared by the preparation method of the chiral porous alloy nanoparticles based on galvanic displacement reaction according to any one of the above.

[0018] Compared with the prior art, the present application has the following beneficial effects: The technical scheme of the present application realizes the transfer of chirality from a sacrifice template to newly generated nanoparticles by using an electrochemical displacement reaction, provides a new way for the preparation of chiral nanomaterials, expands the synthesis method and application range of chiral materials, and obtains binary alloy nanoparticles with an engineeringable composition and mesoporous morphology. These nanoparticles not only have a porous structure with an enhanced specific surface area, but also have unique chiral optical activity, and have potential application value in the fields of asymmetric catalysis, enantiomer differentiation, enantiomer separation, biological detection and biological imaging. The technical scheme of the present application introduces structural chirality as a new research dimension for the electrochemical displacement reaction, deepens the basic understanding of the principle of the electrochemical displacement reaction, and is helpful to promote the theoretical research and technical development in related fields. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Fig. 1 is a UV-Vis spectrum of products obtained at different reaction times in the electrochemical displacement reaction process of Cu CNPs of an embodiment of the present application; wherein (a-I), (a-II), (a-III) are extinction analysis diagrams of reaction times of 0 h, 1 h and 3 h respectively, (b-I), (b-II), (b-III) are CD analysis diagrams of reaction times of 0 h, 1 h and 3 h respectively, and (c-I), (c-II), (c-III) are analysis diagrams of anisotropic g factors of reaction times of 0 h, 1 h and 3 h respectively.

[0020] Figure 2 Fig. 2 is an XRD spectrum of products obtained at different reaction times in the electrochemical displacement reaction process of Cu CNPs of an embodiment of the present application; wherein I, II, III are XRD spectra of reaction times of 0 h, 1 h and 3 h respectively.

[0021] Figure 3 Fig. 3 is a HAADF-STEM image of products obtained at different reaction times in the electrochemical displacement reaction process of Cu CNPs of an embodiment of the present application; wherein (a-I), (a-II), (a-III) are HAADF-STEM images of reaction times of 0 h, 1 h and 3 h respectively.

[0022] Figure 4 Fig. 4 is an EDS atomic percentage mapping result and a particle size analysis diagram of the electrochemical displacement reaction process of Cu CNPs of an embodiment of the present application with the extension of reaction time; wherein (a) is an EDS atomic percentage mapping result, and (b) is a particle size analysis diagram.

[0023] Figure 5 Fig. 5 is a UV-Vis spectrum of Ag CNPs of an embodiment of the present application in the electrochemical displacement reaction process with the extension of reaction time. HAuCl 4UV-Vis spectra of products obtained under different reaction time of electrochemical displacement reaction; wherein, (a-I), (a-II), (a-III) are extinction analysis diagrams of reaction time 0h, 1h, 3h respectively, (b-I), (b-II), (b-III) are CD analysis diagrams of reaction time 0h, 1h, 3h respectively, (c-I), (c-II), (c-III) are analysis diagrams of anisotropic g factor of reaction time 0h, 1h, 3h respectively.

[0024] Figure 6 Ag CNPs of the embodiment of the application are in the process of electrochemical displacement reaction with HAuCl 4 HAADF-STEM images of products obtained under different reaction time of electrochemical displacement reaction; wherein, (a-I), (a-II), (a-III) are HAADF-STEM images of reaction time 0h, 1h, 3h respectively.

[0025] Figure 7 Ag CNPs of the embodiment of the application are in the process of electrochemical displacement reaction with HAuCl 4 EDS atomic percentage mapping results of electrochemical displacement reaction with the extension of reaction time.

[0026] Figure 8 Electrochemical displacement reaction conditions of the embodiment of the application AgNO 3 Influence diagram of concentration, reaction temperature and stirring rate and other conditions on chiral transfer effect.

[0027] Figure 9 Evolution analysis diagram of chiral transfer in the process of Cu CSTs and Ag CNPs electrochemical displacement reaction of the embodiment of the application; wherein, (a-I)~(a-VII) are SEM images of products obtained under reaction time 0h, 1h, 1.5h, 2h, 3h, 5h, 7h, (b-I)~(b-VII) are extinction analysis diagrams of UV-Vis spectra of products obtained under reaction time 0h, 1h, 1.5h, 2h, 3h, 5h, 7h, (c-I)~(c-VII) are CD analysis diagrams of UV-Vis spectra of products obtained under reaction time 0h, 1h, 1.5h, 2h, 3h, 5h, 7h, (d-I)~(d-VII) are anisotropic g factor analysis diagrams of UV-Vis spectra of products obtained under reaction time 0h, 1h, 1.5h, 2h, 3h, 5h, 7h.

[0028] Figure 10Figure 2 is a diagram of the stoichiometric ratio and diameter change of CNPs in the process of the Cu CSTs and Ag CNPs galvanic displacement reaction of the embodiments of the present application; wherein (a) is a diagram of the stoichiometric ratio analysis of CNPs at different reaction times, and (b) is a diagram of the diameter change of CNPs at different reaction times. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present application are further described in detail below. Embodiment 1

[0030] Cu 1-x Ag x Chiral porous alloy nanoparticles, the preparation method comprising the following steps: Step S1, using a grazing angle deposition method to prepare CNPs composed of Cu as a sacrificial template with inherent structural chirality, the height of the sacrificial template is about 100 nm, and the spiral pitch P of the Cu CNPs is about 25 nm.

[0031] Specifically, it includes: preparing a suitable substrate material, fixing it on the rotating platform of the grazing angle deposition device; installing the Cu material with the required purity at the evaporation source position. Set the device parameters, such as vacuum degree, evaporation rate, substrate rotation speed, etc., and carry out grazing angle deposition. During the deposition process, the parameters are accurately controlled to ensure that the CNPs with inherent structural chirality with a height of about 100 nm, a spiral pitch P of the Cu CNPs of about 25 nm, and a spiral pitch P of the Ag CNPs of about 10 nm are prepared as a sacrificial template.

[0032] Step S2, preparing Ag CNPs with Cu CNPs as a sacrificial template Cu 1-x Ag x CNPs: The prepared Cu CNPs are placed in an aqueous solution containing 20 μmol / L AgNO 3 of AgNO3 at room temperature with a stirring rate of 380 rpm. During the reaction process, samples are taken out for characterization at regular time intervals to study the reaction process. Embodiment 2

[0033] Ag 1-x Au x Chiral porous alloy nanoparticles, the preparation method comprising the following steps: Step S1, prepare CNPs with inherent structural chirality composed of Ag as a sacrificial template by glancing angle deposition method, the height of the sacrificial template is about 100 nm, and the spiral pitch P of Ag CNPs is about 10 nm.

[0034] Specifically, it includes: preparing a suitable substrate material and fixing it on the rotating platform of the glancing angle deposition device; installing Cu material with required purity at the evaporation source position. Set the device parameters such as vacuum degree, evaporation rate, substrate rotation speed, etc., and perform glancing angle deposition. During the deposition process, accurately control the parameters to ensure the preparation of CNPs with inherent structural chirality as a sacrificial template, with a height of about 100 nm and a spiral pitch P of Ag CNPs of about 10 nm.

[0035] Step S2, prepare Ag 1-x Au x CNPs using Ag CNPs as a sacrificial template: place the prepared Ag CNPs in a saturated NaCl solution of 20 μmol / L HAuCl 4 , and react at room temperature with a stirring speed of 380 rpm. During the reaction process, take out the sample for characterization at regular time intervals to study the reaction progress.

[0036] Characterize the nanoparticles prepared above, including: 1) Composition analysis: use energy dispersive spectroscopy (EDS) to analyze the elements of the nanoparticles after reaction to obtain their composition information; use X-ray photoelectron spectroscopy (XPS) to further accurately analyze the surface element composition and chemical state to determine the stoichiometric ratio of the alloy CNPs.

[0037] 2) Structure characterization: observe the morphology, size and distribution of the nanoparticles by scanning electron microscopy (SEM); use transmission electron microscopy (TEM) to analyze the microstructure of the nanoparticles in depth to determine whether they are mesoporous structures; use X-ray diffraction (XRD) to analyze the crystal structure of the nanoparticles.

[0038] 3) Optical property characterization: use ultraviolet-visible spectrometer to measure the extinction spectrum of the nanoparticles, use circular dichroism spectrometer to detect the CD signal, use the anisotropy g factor to quantitatively evaluate the optical activity of the nanoparticles, and study the influence of chirality transfer on the optical properties.

[0039] In Example 1, the ultraviolet-visible spectra of the products obtained at different reaction times in the galvanic displacement reaction process of Cu CNPs are as shown in Figure 1 , the XRD spectra are as shown in Figure 2 , and the HAADF-STEM images are as shown inFigure 3 EDS atomic percentage mapping results and particle size analysis chart are shown in FIG. 2A and FIG. 2B, respectively. Figure 4 As shown in FIG. 2A and FIG. 2B, the above results show the changes of composition, structure and optical properties of the nanoparticles during the reaction, which confirms that the chiral transfer from the sacrificial template to the newly generated nanoparticles can be achieved by the galvanic replacement reaction.

[0040] In Example 2, Ag CNPs were generated from RH-Cu SCTs (P≈25 nm, H≈100 nm) by GRR in the presence of AgNO3 (C=20 μmol / L, T=25 °C, Rs=380 rpm). HAuCl 4 The related characterization results under different reaction times (0 h, 1 h, 3 h) during the galvanic replacement reaction, including UV-Vis spectra (extinction, CD, anisotropy g factor), are shown in FIG. 3A, FIG. 3B and FIG. 3C, respectively. Figure 5 The HAADF-STEM images are shown in FIG. 4A, FIG. 4B and FIG. 4C, respectively. Figure 6 The EDS atomic percentage mapping results are shown in FIG. 5A, FIG. 5B and FIG. 5C, respectively. Figure 7 The above results show the chiral transfer, composition change and mesoporous morphology formation process of the generated Ag CNPs, which confirms that the chiral transfer from the sacrificial template to the newly generated nanoparticles can be achieved by the galvanic replacement reaction, and the obtained product not only has a porous structure with enhanced specific surface area, but also has unique chiral optical activity, which is specifically manifested as the chiral optical properties being transferred from the original chiral template to the newly generated binary alloy through the galvanic replacement reaction. Ag 1-x Au x The chiral transfer, composition change and mesoporous morphology formation process of the generated Ag CNPs, which confirms that the chiral transfer from the sacrificial template to the newly generated nanoparticles can be achieved by the galvanic replacement reaction, and the obtained product not only has a porous structure with enhanced specific surface area, but also has unique chiral optical activity, which is specifically manifested as the chiral optical properties being transferred from the original chiral template to the newly generated binary alloy through the galvanic replacement reaction.

[0041] The above structure proves that the method of galvanic replacement reaction can be used to prepare chiral porous alloy nanoparticles.

[0042] On the basis of Example 1, the concentration of AgNO3 (C), the reaction temperature (T) and the stirring rate (Rs) were changed. AgNO 3 The concentration, reaction temperature and stirring rate were changed, and the chiral transfer index ICT was defined to obtain the effect of the concentration, reaction temperature and stirring rate on the chiral transfer. AgNO 3 The effect of the concentration, reaction temperature and stirring rate on the chiral transfer was obtained, and the GRR (galvanic replacement reaction) was used to optimize the chiral transfer from the RH-Cu SCTs (P≈25 nm, H≈100 nm). The GRR was carried out in an aqueous solution, and the reaction was continued for a long enough time to generate Ag nanoparticles (CNPs), and the relationship between the Ag nanoparticles and the concentration of silver nitrate (C), the temperature (T) and the stirring rate (Rs) was studied, and the results are shown in FIG. 6A, FIG. 6B and FIG. 6C, respectively. Figure 8 Figure 8 In FIG. 6A, FIG. 6B and FIG. 6C, (a) and (b) are the anisotropy g factor spectra of the RH-Cu nanoparticles at 0 hours and 24 hours of the GRR reaction, respectively (reaction conditions: C=20 μmol / L, T=25 °C, Rs=380 rpm). Among them Figure 8 ​The anisotropic g-factor signal in the 380-650 nm wavelength range in (a) in FIG. 38 is fitted by a Gaussian function, consisting of one dielectric circular dichroism (CD) peak (short wavelength region) and one transverse CD peak (long wavelength region, marked by the shaded part). The index of chirality transfer (ICT) is defined as the ratio of Ag,Ag(the integrated area of the doublet anisotropic g-factor peak of the transverse CD mode of Ag NPs generated by GRR, marked by the shaded part in (b) in FIG. 8) to Ag,Cu(the integrated area of the anisotropic g-factor peak of the transverse CD mode of Cu NPs, Figure 8 in (a) in FIG. 38. Figure 8 in (c) in FIG. 38 is a plot of the ICT as a function of C, T and Rs. It can be seen that the index of chirality transfer is high when the reaction is carried out at room temperature with a stirring rate of 380 rpm.

[0043] Figure 9 and Figure 10 is the evolution of chirality transfer during the galvanic displacement reaction between Cu CSTs of Example 1 and Ag CNPs of Example 2, including SEM images, UV-Vis spectra (extinction, CD, anisotropic g-factor), stoichiometric ratio and diameter changes of CNPs at different reaction times (0 h - 7 h), clearly showing the changes in the structure and optical properties of nanoparticles over time during the process of chirality transfer. It can be seen that as the reaction time increases, the chirality of the monometallic nanoparticle template can be transferred through GRR to form binary alloy nanoparticles with tunable material properties, composition and morphology. This material can lay the foundation for the development of various chirality-related applications (such as asymmetric catalysis, enantiomer discrimination, enantiomer separation, biological detection and biological imaging).

[0044] The above is a further detailed description of the present application in combination with specific preferred embodiments, and cannot be considered as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, several simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be considered as falling within the protection scope of the present application.

Claims

1. A method for the preparation of chiral porous alloy nanoparticles based on galvanic displacement reactions, characterized in that, The method comprises the following steps: S1, using a glancing angle deposition method to prepare CNPs with inherent structural chirality composed of Cu or Ag as a sacrificial template; Step S2, stirring the sacrificial template in an electrolyte containing ions of metal A, and performing an electroreplacement reaction for 1 h or more to obtain Cu 1-x A x or Ag 1-x A x chiral porous alloy nanoparticles, 0≤x≤1.

2. The method for preparing chiral porous alloy nanoparticles based on galvanic replacement reaction according to claim 1, characterized in that: The height of the sacrificial template is 50-200 nm, the spiral pitch P of the CNPs with inherent structural chirality composed of Cu is 20-30 nm, and the spiral pitch of the CNPs with inherent structural chirality composed of Ag is 5-15 nm.

3. The method for the preparation of chiral porous alloy nanoparticles based on galvanic replacement reaction according to claim 2, characterized in that: The height of the Cu sacrificial template nanoparticles is 150-200 nm, and the height of the Ag sacrificial template nanoparticles is 50-150 nm; the spiral pitch P of the CNPs with inherent structural chirality composed of Cu is 25 nm, and the spiral pitch of the CNPs with inherent structural chirality composed of Ag is 10 nm.

4. The method of claim 1, wherein the method comprises: In step S2, the electroreplacement reaction time is 1 h-7 h.

5. The method of claim 1, wherein the method comprises: In step S2, the stirring rate is 350-450 rpm; and in the electrolyte, the concentration of the ions containing the A metal is 10-30 μmol / L.

6. The method according to any one of claims 1 to 5, wherein the method is characterized by: The ion containing the metal A is Ag + 、 AuCl 4 - 、 PtCl 4 2- or PdCl 4 2- .

7. The method according to claim 6, wherein the method is characterized by: Preparation Cu 1-x Ag x In this case, the electrolyte is an aqueous solution containing AgNO 3 and the reaction is carried out at room temperature with a stirring rate of 380 rpm; Preparation Ag 1-x Au x In this case, the electrolyte is a saturated NaCl solution containing 20 pmol / L HAuCl 4 of the compound.

8. Chiral porous alloy nanoparticles based on galvanic displacement reactions, characterized in that: The method is prepared by using the preparation method of the chiral porous alloy nanoparticles based on an electroreplacement reaction according to any one of claims 1-6.

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