Zinc sulfide-lead-copper quaternary quantum dot loaded with gold single atoms and preparation method of zinc sulfide-lead-copper quaternary quantum dot
By loading gold single atoms onto the surface of zinc sulfide, lead, and copper quaternary quantum dots using underpotential deposition and chemical substitution, the problem of low utilization of precious metals was solved, achieving efficient and low-cost preparation of fluorescent materials suitable for industrialization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ARMY ENG UNIV OF PLA
- Filing Date
- 2025-12-05
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies struggle to efficiently load gold single atoms onto the surface of zinc-lead-copper quaternary quantum dots, resulting in low utilization of precious metals, high costs, and difficulty in precisely controlling electronic structure and fluorescence efficiency.
A room-temperature aqueous electrochemical method combining underpotential deposition and chemical substitution was used to deposit copper single atoms on the surface of zinc-lead-copper quaternary quantum dots. Then, gold single atoms were loaded through a chemical substitution reaction. The electronic structure and fluorescence properties were controlled by parameters such as electrolyte concentration, deposition potential and time.
This method achieves efficient loading of gold single atoms, reduces production costs, improves fluorescence efficiency, and simplifies the preparation process, making it suitable for industrial applications.
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Figure CN121820641A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a kind of gold single atom loaded zinc lead copper sulfide quaternary quantum dots and preparation method thereof, belong to the preparation technical field of quantum dots. BACKGROUND
[0002] As a kind of zero-dimensional semiconductor nanomaterial, sulfide quantum dots show significant quantum size effect, strong quantum confinement and edge effect, and large stokes shift, and show great application prospect in optoelectronic devices, photoelectrocatalysis, quantum display and biological imaging etc.
[0003] It is found through research that there is relatively strong binding capacity between sulfur atom in zinc lead copper sulfide quaternary quantum dots and the atom of some noble metal elements such as gold, when gold is loaded on the surface of the zinc lead copper sulfide quaternary quantum dots, the physical and chemical properties of the zinc lead copper sulfide quaternary quantum dots are changed and regulated through the strong electronic interaction between sulfur atom and gold atom, especially the fluorescence efficiency is further improved, so as to obtain a phosphor material with better luminescent performance. However, as a kind of noble metal, the low reserves and high price of gold in nature limit its application in the preparation of various high-performance materials, and it is difficult to accurately establish the relationship between the electronic structure of the substrate material and the fluorescence efficiency at atomic level. If the size of gold nanoparticles loaded on the surface of zinc lead copper sulfide quaternary quantum dots is reduced to single atom level, the preparation cost of the material can be reduced by maximizing the utilization efficiency of gold atoms, and the characterization and monitoring of zinc lead copper sulfide quaternary quantum dots material at single atom level can be effectively realized. However, the size of quantum dots is generally very small, which poses a challenge to the loading of metal single atoms on the surface of quantum dots and the obtaining of the morphology of metal single atoms by conventional instruments. SUMMARY
[0004] The present application aims to overcome the deficiencies in the prior art, and provides a kind of gold single atom loaded zinc lead copper sulfide quaternary quantum dots and preparation method thereof. Through the room temperature aqueous electrochemical method of underpotential deposition combined with chemical displacement, efficient loading of gold single atom is realized, the fluorescence performance can be regulated, and the method has the advantages of high efficiency and low cost, and is suitable for industrialization.
[0005] To achieve the above-mentioned purpose, the present application is realized by using the following technical scheme: On the one hand, the present application discloses a preparation method of gold single atom loaded zinc lead copper sulfide quaternary quantum dots, comprising the following steps: Preparation of zinc lead copper sulfide quaternary quantum dots; Disperse the zinc lead copper sulfide quaternary quantum dots in water phase to form a quantum dot suspension; mix the quantum dot suspension with an acid source, and then add a first copper source to prepare an electrolyte after constant volume and deoxygenation treatment in an electrolytic cell; After the single-atom copper is deposited on the surface of the quantum dots in the electrolyte by under-potential deposition under the constant potential condition, a mixed solution of a gold source is added to the deposited electrolyte to perform a chemical displacement reaction, thereby obtaining a quantum dot suspension loaded with single-atom gold; The quantum dot suspension loaded with single-atom gold is purified and dried to obtain a zinc lead copper sulfide four-element quantum dot loaded with single-atom gold.
[0006] Further, the preparation method of the zinc lead copper sulfide four-element quantum dot is as follows: The zinc source, the sulfur source, the lead source and the second copper source are mixed with an aqueous solvent to form a homogeneous zinc precursor solution, a sulfur precursor solution, a lead precursor solution and a copper precursor solution; Under the first stirring condition, the surface stabilizer is mixed with boiling water, and then the zinc precursor solution, the sulfur precursor solution, the lead precursor solution and the copper precursor solution are sequentially added, followed by a heating reflux reaction to form a suspension containing zinc lead copper sulfide four-element quantum dots; After the suspension containing zinc lead copper sulfide four-element quantum dots is subjected to a first centrifugation, washing and drying, a purified zinc lead copper sulfide four-element quantum dot is obtained.
[0007] Further, the zinc source includes zinc acetate dihydrate, the sulfur source includes sodium sulfide nonahydrate, the lead source includes lead acetate trihydrate, and the second copper source includes copper acetate monohydrate; The concentration of zinc in the zinc precursor solution is 250.0 mmol / L; The concentration of sulfur in the sulfur precursor solution is 250.0 mmol / L; The concentration of lead in the lead precursor solution is 4.0 mmol / L; The concentration of copper in the copper precursor solution is 12.5 mmol / L.
[0008] Further, the stirring speed of the first stirring condition is 900-1100 rpm; The surface stabilizer includes chitosan; The amount of boiling water added is 80-120 mL, and the temperature of the boiling water is 90-110℃; The molar ratio of zinc in the zinc precursor solution, sulfur in the sulfur precursor solution, lead in the lead precursor solution and copper in the copper precursor solution is 62.5:62.5:1:3.125; The molar ratio of zinc in the zinc precursor solution to the surface stabilizer is 10000:1; The heating temperature of the heating reflux reaction is 90-110 ℃, and the reaction time of the heating reflux reaction is 3-5 hours.
[0009] Further, the rotation speed of the first centrifugation is 12000-13000 rpm, and the time of the first centrifugation is 5-7 minutes. The solvent for the washing includes deionized water, and the number of times of the washing is 3-4 times, and the amount of the deionized water added each time is 8-12 mL. The drying is vacuum drying at room temperature, and the time of the drying is 24-36 hours.
[0010] Further, the concentration of the zinc sulfide lead copper quaternary quantum dots in the quantum dot suspension is 20-30 mg / mL. The acid source is a concentrated sulfuric acid solution, and the volume ratio of the quantum dot suspension to the acid source is 100:8-9. The three-electrode system including a working electrode, a counter electrode and a reference electrode is assembled in the electrolytic cell, and inert gas is introduced to create an oxygen-free environment, and the inert gas includes argon. The first copper source is a copper sulfate solution, and the molar ratio of the acid source to the first copper source in the electrolyte is 10:1.
[0011] Further, the step of underpotential deposition is as follows: A constant potential is determined as the potential for underpotential deposition; Copper monomers are deposited on the surface of the quantum dots in the electrolyte by underpotential deposition until the cathode current reaches a stable state, and the value of the cathode current meets a preset current threshold, and the deposition is stopped; The constant potential is 0.05-0.15 V, the stirring speed of the underpotential deposition is 900-1100 rpm, and the reaction time of the underpotential deposition is 11-13 hours.
[0012] Further, the mixed solution of the gold source includes a mixed solution of sodium chloroaurate dihydrate and sulfuric acid, the concentration of sodium chloroaurate dihydrate in the mixed solution is 50 mmol / L, and the concentration of sulfuric acid in the mixed solution is 50 mmol / L. The stirring speed of the chemical displacement reaction is 1500-1800 rpm, and the reaction time of the chemical displacement reaction is 6-10 hours.
[0013] Further, the step of purification and drying is as follows: The quantum dot suspension loaded with gold monomers is subjected to reduced pressure filtration to obtain a filtrate, and the filtrate is pretreated with liquid nitrogen to obtain a pretreated filtrate. The pretreated filtrate is freeze-dried to obtain a dried crude product. The dried crude product is re-dispersed in water or an organic solvent, and after secondary centrifugal separation, a purified solid is obtained; The purified solid is vacuum dried at room temperature to obtain the final gold single atom loaded zinc lead copper sulfide quaternary quantum dots; The drying time of the freeze-drying is 24-36 hours; The rotation speed of the secondary centrifugation is 16000-20000 rpm, and the time of the secondary centrifugation is 50-80 minutes; The time of the vacuum drying is 24-36 hours.
[0014] In another aspect, the application discloses a gold single atom loaded zinc lead copper sulfide quaternary quantum dot, which is prepared by the preparation method of the gold single atom loaded zinc lead copper sulfide quaternary quantum dot.
[0015] Compared with the prior art, the application has the following beneficial effects: The gold single atom loaded zinc lead copper sulfide quaternary quantum dot and the preparation method thereof have the following advantages: firstly, the whole preparation process, especially the single atom loading process, is mainly carried out in an aqueous phase and at room temperature, and an electrochemical method is used, so that the traditional high-temperature heat treatment or the use of a large amount of toxic organic solvents is avoided, and the energy consumption and environmental pollution are significantly reduced; secondly, by combining the underpotential deposition and chemical displacement strategies, the gold is efficiently loaded in the form of single atoms, so that the utilization rate of the noble metal gold atoms is maximized, and the production cost of the high-performance material is effectively reduced; in addition, by adjusting the concentration of the electrolyte, the deposition potential, the underpotential deposition time and other experimental parameters of the preparation process, the electronic structure and the fluorescence efficiency of the prepared gold single atom loaded zinc lead copper sulfide quaternary quantum dots can be regulated. The preparation method has the advantages of short process flow, simple operation, low cost and stable process, and is suitable for industrial implementation. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is a flow step diagram of the preparation method of the gold single atom loaded zinc lead copper sulfide quaternary quantum dot provided in Embodiment 1 of the application; Figure 2 is a flow schematic diagram of the preparation method of the gold single atom loaded zinc lead copper sulfide quaternary quantum dot provided in Embodiment 1 of the application; Figure 3 is a comparison diagram of photoluminescence spectra of the zinc lead copper sulfide quaternary quantum dot provided in Embodiment 1 of the application, the zinc sulfide binary quantum dot provided in Embodiment 2 of the application and the zinc lead ternary quantum dot provided in Embodiment 3 of the application; Figure 4 is a comparison diagram of photoluminescence spectra of the gold single atom loaded molybdenum disulfide quantum dot before and after the preparation provided in Comparative Example 1 of the application; Figure 5 is a photoluminescence spectrum comparison chart of the cadmium sulfide quantum dots provided by Comparative Example 2 of the present application before and after loading of gold monatomic atoms. DETAILED DESCRIPTION
[0017] The present application will be further described below with reference to the drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.
[0018] The present application discloses a preparation method of gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots, as shown in formula (I), comprising the following steps: Figure 1 The preparation method of the gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots comprises the following steps: Preparation of zinc lead copper sulfide quaternary quantum dots; Disperse the zinc lead copper sulfide quaternary quantum dots in an aqueous phase to form a quantum dot suspension; mix the quantum dot suspension with an acid source and then add water to prepare an electrolyte; and then perform deoxygenation treatment on the electrolyte in an electrolytic cell, and then add a first copper source to the electrolyte. Under a constant potential condition, deposit copper monatomic atoms on the surface of the quantum dots in the electrolyte by underpotential deposition, then add a mixed solution of a gold source to the deposited electrolyte, and then perform a chemical displacement reaction to obtain a quantum dot suspension loaded with gold monatomic atoms. Purify and dry the quantum dot suspension loaded with gold monatomic atoms to obtain gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots.
[0019] The technical concept of the present application is as follows: first, the entire preparation process, especially the monatomic atom loading link, is mainly carried out in an aqueous phase and at room temperature, and an electrochemical method is used to avoid traditional high-temperature heat treatment or the use of a large amount of toxic organic solvents, thereby significantly reducing energy consumption and environmental pollution. Second, by combining underpotential deposition and chemical displacement, efficient loading of gold in the form of monatomic atoms is realized, the utilization rate of noble metal gold atoms is maximized, and the production cost of high-performance materials is effectively reduced. In addition, by adjusting the concentration of the electrolyte, the deposition potential, the underpotential deposition time and other experimental parameters of the preparation process, the electronic structure and fluorescence efficiency of the prepared gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots can be controlled. The preparation method of the present application has the advantages of short process flow, simple operation, low cost and stable process, and is suitable for industrial implementation.
[0020] As shown in formula (I) and formula (II), the specific steps are as follows: Figure 1 and Figure 2 As shown in formula (I) and formula (II), the specific steps are as follows: Step 1, preparation of zinc lead copper sulfide quaternary quantum dots.
[0021] The preparation method of the zinc lead copper sulfide quaternary quantum dots is as follows: 1.1, respectively, zinc source, sulfur source, lead source and the second copper source and water solvent mixed, form a certain concentration of homogeneous zinc precursor solution, sulfur precursor solution, lead precursor solution and copper precursor solution.
[0022] Specifically, the zinc source includes zinc acetate dihydrate, the sulfur source includes sodium sulfide nonahydrate, the lead source includes lead acetate trihydrate, and the second copper source includes copper acetate monohydrate; The concentration of zinc element in the zinc precursor solution is 250.0 mmol / L; The concentration of sulfur element in the sulfur precursor solution is 250.0 mmol / L; The concentration of lead element in the lead precursor solution is 4.0 mmol / L; The concentration of copper element in the copper precursor solution is 12.5 mmol / L.
[0023] Specifically, 2 mL of deionized water is added to 0.1098 g of zinc acetate dihydrate to form a homogeneous zinc precursor solution of zinc acetate dihydrate; 2 mL of deionized water is added to 0.1201 g of sodium sulfide nonahydrate to form a homogeneous sulfur precursor solution of sodium sulfide nonahydrate; 2 mL of deionized water is added to 0.0030 g of lead acetate trihydrate to form a homogeneous lead precursor solution of lead acetate trihydrate; 2 mL of deionized water is added to 0.0050 g of copper acetate monohydrate to form a homogeneous copper precursor solution of copper acetate monohydrate.
[0024] 1.2, under the first stirring condition, the surface stabilizer is mixed with boiling water, then the zinc precursor solution, the sulfur precursor solution, the lead precursor solution and the copper precursor solution are added in turn, and then the heating reflux reaction is carried out to form a suspension containing zinc lead copper sulfide quantum dots.
[0025] Specifically, the stirring speed of the first stirring condition is 900-1100 rpm; The surface stabilizer includes chitosan (C6H11NO4)n M W = 100000); The amount of boiling water added is 80-120 mL, and the temperature of the boiling water is 90-110 ℃; The molar ratio of zinc element in the zinc precursor solution, sulfur element in the sulfur precursor solution, lead element in the lead precursor solution and copper element in the copper precursor solution is 62.5:62.5:1:3.125; The molar ratio of zinc element in the zinc precursor solution to the surface stabilizer is 10000:1; The heating temperature of the heating reflux reaction is 90-110 ℃, and the reaction time of the heating reflux reaction is 3-5 hours.
[0026] Specifically, 80-120 mL of deionized water is heated to boiling (90-110 ℃), and 5 mg of chitosan is added to the boiling water under stirring at a speed of 900-1100 rpm. M W = 100000), and then the zinc precursor solution, the sulfur precursor solution, the lead precursor solution and the copper precursor solution are sequentially added. The reaction solution is heated to reflux at 90-110 ℃ for 3-5 hours. After the reaction is completed, a suspension of zinc-lead-copper sulfide quaternary quantum dots is formed.
[0027] 1.3, the suspension containing zinc-lead-copper sulfide quaternary quantum dots is centrifuged, washed and dried to obtain purified zinc-lead-copper sulfide quaternary quantum dots.
[0028] Specifically, the speed of the first centrifugation is 12000-13000 rpm, and the time of the first centrifugation is 5-7 minutes; The washing solvent includes deionized water, and the number of washing is 3-4 times, and the amount of deionized water added each time is 8-12 mL; The drying is vacuum drying at room temperature, and the drying time is 24-36 hours.
[0029] Specifically, the suspension containing zinc-lead-copper sulfide quaternary quantum dots is centrifuged at a speed of 12000-13000 rpm for 5-7 minutes, and the precipitate is collected and washed with 8-12 mL of deionized water. The number of washing is 3-4 times. After washing, centrifugal separation is performed, and then vacuum drying is performed at room temperature for 24-36 hours to obtain zinc-lead-copper sulfide quaternary quantum dots.
[0030] Step 2, disperse the zinc-lead-copper sulfide quaternary quantum dots in the aqueous phase to form a quantum dot suspension; mix the quantum dot suspension with an acid source and make up the volume, then pour it into an electrolytic cell for oxygen removal treatment, and then add a first copper source to prepare an electrolyte.
[0031] Specifically, the concentration of zinc-lead-copper sulfide quaternary quantum dots in the quantum dot suspension is 20-30 mg / mL; The acid source is concentrated sulfuric acid solution, and the volume ratio of the quantum dot suspension to the acid source is 100:8-9; The electrolytic cell is equipped with a three-electrode system including a working electrode, a counter electrode and a reference electrode, and inert gas is introduced to create an oxygen-free environment. The inert gas includes argon; The first copper source is copper sulfate solution, and the molar ratio of the acid source to the first copper source in the electrolyte is 10:1.
[0032] Specifically, 2-3 g of the zinc-lead-copper sulfide quaternary quantum dots are added into 100 mL of deionized water to prepare a 20-30 mg / mL zinc-lead-copper sulfide quaternary quantum dot suspension. Then, 10 mL of the zinc-lead-copper sulfide quaternary quantum dot suspension is taken, 0.815 mL of concentrated sulfuric acid is added, and deionized water is added to dilute to 30 mL, and then poured into an electrolytic cell. In the electrolytic cell, a glassy carbon electrode, a platinum electrode and a silver chloride electrode are sequentially assembled as a working electrode, a counter electrode and a reference electrode, respectively, and then pure argon gas is used to remove dissolved oxygen in the sealed system, and then a copper sulfate solution is added to the electrolytic cell to prepare an electrolyte of a mixed solution of sulfuric acid and copper sulfate; in the prepared electrolyte, the concentrations of sulfuric acid and copper sulfate are 0.5 mol / L and 50 mmol / L, respectively.
[0033] Step 3, after the copper monomers are deposited on the surface of the quantum dots in the electrolyte under the condition of constant potential, a mixed solution of a gold source is added to the deposited electrolyte to perform a chemical displacement reaction to obtain a quantum dot suspension loaded with gold monomers.
[0034] Specifically, the step of under-potential deposition is as follows: a constant potential is determined as the potential for under-potential deposition; copper monomers are deposited on the surface of the quantum dots in the electrolyte until the cathode current reaches a stable state and the value of the cathode current meets a preset current threshold, and then the deposition is stopped; wherein the constant potential is 0.05-0.15 V; the stirring speed for under-potential deposition is 900-1100 rpm, and the reaction time for under-potential deposition is 11-13 hours; The mixed solution of the gold source includes a mixed solution of sodium chloroaurate dihydrate and sulfuric acid, and the concentration of sodium chloroaurate dihydrate in the mixed solution is 50 mmol / L; the concentration of sulfuric acid in the mixed solution is 50 mmol / L; The stirring speed for the chemical displacement reaction is 1500-1800 rpm, and the reaction time for the chemical displacement reaction is 6-10 hours.
[0035] Specifically, under the stirring speed of 900-1100 rpm, a constant potential of 0.100 V is selected as the potential for under-potential deposition to load copper monomers on the surface of the zinc-lead-copper sulfide quaternary quantum dots. When the cathode current is stable and tends to be 0, the reaction time is 11-13 hours, and the under-potential deposition process of Cu monomers is stopped. The mixed solution of sodium chloroaurate dihydrate and sulfuric acid is added dropwise in the electrolytic cell, and then the reaction solution is subjected to a chemical displacement reaction at room temperature under the stirring speed of 1500-1800 rpm, and the reaction time is 6-10 hours. After the reaction is completed, a gold monomer-loaded zinc-lead-copper sulfide quaternary quantum dot suspension is formed.
[0036] In the chemical displacement process, the mixed solution of sodium chloroaurate dihydrate and sulfuric acid is obtained by dissolving 0.5967 g of sodium chloroaurate dihydrate in 20 mL of deionized water, then adding 81.5 μL of concentrated sulfuric acid, and diluting with deionized water to 30 mL. The final concentration of sodium chloroaurate dihydrate and sulfuric acid in the mixture is 50 mmol / L.
[0037] Step 4, purifying and drying the gold monatomic atom loaded quantum dot suspension to obtain gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots.
[0038] The purification and drying step is: Specifically, the gold monatomic atom loaded quantum dot suspension is subjected to vacuum suction filtration to obtain a filtrate, and the filtrate is pretreated with liquid nitrogen to obtain a pretreated filtrate. The pretreated filtrate is freeze-dried to obtain a dried crude product. The dried crude product is redispersed in water or an organic solvent, and after secondary centrifugal separation, a purified solid is obtained. The purified solid is vacuum dried at room temperature to obtain the final gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots. The freeze-drying time is 24-36 hours. The secondary centrifugation speed is 16000-20000 revolutions per minute, and the secondary centrifugation time is 50-80 minutes. The vacuum drying time is 24-36 hours.
[0039] Specifically, the gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dot suspension is subjected to vacuum suction filtration, then pretreated with liquid nitrogen, and freeze-dried for 24-36 hours. After freeze-drying is completed, 3-4 mL of deionized water is added to the obtained crude product for ultrasonic dispersion, and the precipitate is collected by centrifugation and vacuum dried at room temperature for 24-36 hours, to obtain the gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots.
[0040] Example 1: The present example 1 provides a preparation method of gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dots, and the specific steps are as follows: Step 1, preparing zinc lead copper sulfide quaternary quantum dots.
[0041] 1.1, 0.1098 g of zinc acetate dihydrate was dissolved in 2 mL of deionized water to form a homogeneous zinc precursor solution of zinc acetate dihydrate; 0.1201 g of sodium sulfide nonahydrate was dissolved in 2 mL of deionized water to form a homogeneous sulfur precursor solution of sodium sulfide nonahydrate; 0.0030 g of lead acetate trihydrate was dissolved in 2 mL of deionized water to form a homogeneous lead precursor solution of lead acetate trihydrate; 0.0050 g of copper acetate monohydrate was dissolved in 2 mL of deionized water to form a homogeneous copper precursor solution of copper acetate monohydrate; 1.2, 100 mL of deionized water was added to a 250 mL round-bottom flask and heated to boiling (100 ℃), 5 mg of chitosan was added to the boiling water at a stirring speed of 1000 rpm M W = 100000), and then the zinc precursor solution, the sulfur precursor solution, the lead precursor solution and the copper precursor solution were sequentially added, and then the reaction solution was heated to reflux at 100 ℃ for 4 hours, and a suspension containing zinc lead copper sulfide quaternary quantum dots was formed after the reaction was completed; 1.3, the suspension containing zinc lead copper sulfide quaternary quantum dots was centrifuged at a speed of 13000 rpm for 6 minutes, the precipitate was collected, washed with 10 mL of deionized water for 3 times, and then centrifuged at a speed of 13000 rpm, and vacuum dried at room temperature for 30 hours, to obtain zinc lead copper sulfide quaternary quantum dots.
[0042] Step 2, preparation of electrolyte.
[0043] 2.5 g of the prepared zinc lead copper sulfide quaternary quantum dots were added to 100 mL of deionized water for ultrasonic dispersion, to prepare a suspension of zinc lead copper sulfide quaternary quantum dots at a concentration of 25 mg / mL.
[0044] Then 10 mL of the prepared suspension was measured, 0.815 mL of concentrated sulfuric acid was added, and the volume was diluted to 30 mL with deionized water, and then poured into the electrolysis cell.
[0045] The glassy carbon electrode, platinum electrode and silver chloride electrode were sequentially assembled in the electrolysis cell as the working electrode, counter electrode and reference electrode, respectively, and then the dissolved oxygen in the sealed system was removed with pure argon, and a copper sulfate solution obtained by dissolving 0.2394 g of copper sulfate in 2 mL of deionized water was added to the electrolysis cell.
[0046] The concentrations of sulfuric acid and copper sulfate in the finally prepared electrolyte were 0.5 mol / L and 50 mmol / L, respectively.
[0047] Step 3, preparation of quantum dot suspension loaded with gold single atom.
[0048] The copper monatomic atom is loaded on the surface of the zinc lead copper sulfide quaternary quantum dot at 0.100 V as the potential for underpotential deposition at a stirring speed of 1000 rpm. When the cathode current is stable and tends to be 0, the underpotential deposition process of the copper monatomic atom is stopped.
[0049] A 50 mmol / L sodium chloroaurate dihydrate and 50 mmol / L sulfuric acid mixed solution is prepared by dropwise adding a mixed solution of 0.5967 g of sodium chloroaurate dihydrate dissolved in 20 mL of deionized water, adding 81.5 μL of concentrated sulfuric acid, and diluting with deionized water to 30 mL, and then the reaction solution is subjected to a chemical displacement reaction at room temperature under a stirring speed of 1600 rpm. After 8 hours, a gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dot suspension is formed.
[0050] Step 4, obtaining the gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dot.
[0051] The above gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dot suspension is subjected to vacuum filtration, and then the filtrate is pretreated with liquid nitrogen to obtain a pretreated filtrate. After the pretreated filtrate is subjected to freeze-drying for three days, a dried crude product is obtained.
[0052] After 3 mL of deionized water is added to the dried crude product for ultrasonic dispersion, the precipitate is collected after centrifugation at a speed of 18000 rpm for 60 minutes to obtain a purified solid.
[0053] The purified solid is vacuum dried at room temperature for 30 hours to finally obtain a gold monatomic atom loaded zinc lead copper sulfide quaternary quantum dot.
[0054] Embodiment 2 provides a preparation method of a gold monatomic atom loaded zinc sulfide binary quantum dot. The difference between this embodiment 2 and embodiment 1 is that step 1.1 is: 0.1098 g of zinc acetate dihydrate is dissolved in 2 mL of deionized water to form a homogeneous zinc precursor solution of zinc acetate dihydrate; 0.1201 g of sodium sulfide nonahydrate is dissolved in 2 mL of deionized water to form a homogeneous sulfur precursor solution of sodium sulfide nonahydrate (no formation of lead precursor solution and copper precursor solution). Step 1.2 is: 100 mL of deionized water is added to a 250 mL round-bottom flask and heated to boiling (100 ℃), and 5 mg of chitosan is added to the above boiling water at a stirring speed of 1000 rpm. M W= 100000), and then the reaction solution was heated to reflux at 100°C for 4 hours, and a suspension containing zinc sulfide binary quantum dots was formed after the reaction was completed.
[0055] Example 3: The present example 3 provides a preparation method of gold single atom loaded zinc sulfide lead ternary quantum dots; The difference between the present example 3 and example 1 is that step 1.1 is: 0.1098 g of zinc acetate dihydrate is dissolved in 2 mL of deionized water to form a homogeneous zinc precursor solution of zinc acetate dihydrate; 0.1201 g of sodium sulfide nonahydrate is dissolved in 2 mL of deionized water to form a homogeneous sulfur precursor solution of sodium sulfide nonahydrate; and 0.0030 g of lead acetate trihydrate is dissolved in 2 mL of deionized water to form a homogeneous lead precursor solution of lead acetate trihydrate (no copper precursor solution is formed). Step 1.2 is: 100 mL of deionized water is added to a 250 mL round bottom flask, and heated to boiling (100°C), and 5 mg of chitosan is added to the boiling water at a stirring speed of 1000 rpm. M W = 100000), and then the reaction solution was heated to reflux at 100°C for 4 hours, and a suspension containing zinc sulfide binary quantum dots was formed after the reaction was completed.
[0056] From Figure 3 It can be seen that the fluorescence intensity of the zinc sulfide lead copper quaternary quantum dots of example 1 is significantly higher than that of the zinc sulfide binary quantum dots of example 2 and the zinc sulfide lead ternary quantum dots of example 3. This phenomenon is because the recombination between the conduction band electrons and the valence band holes of the zinc sulfide quantum dots as a semiconductor material will produce a certain degree of fluorescence emission. After doping lead ions into the zinc sulfide quantum dots, an electron transfer process from the lead ions to the zinc sulfide quantum dots occurs, causing the recombination probability between the conduction band electrons and the valence band holes of the zinc sulfide quantum dots to decrease, thereby causing a certain degree of fluorescence quenching. On this basis, further doping of copper ions causes a synergistic effect between lead ions and copper ions, causing electrons in the zinc sulfide quantum dots to transfer to copper ions, causing the recombination probability between the conduction band electrons and the valence band holes of the zinc sulfide quantum dots to increase significantly, and thus the fluorescence to increase significantly. In order to obtain quantum dot materials with excellent fluorescence performance, we added lead precursor solution and copper precursor solution to the preparation system of zinc sulfide quantum dots, and then doped lead ions and copper ions into the zinc sulfide quantum dots, to prepare zinc sulfide lead copper quaternary quantum dots with very strong fluorescence intensity.
[0057] Comparative Example 1: This comparative example 1 provides a method for preparing gold monatomic atom loaded molybdenum disulfide quantum dots; The difference between comparative example 1 and example 1 is that the steps are: Step 1, preparation of molybdenum disulfide quantum dots.
[0058] In a 250 mL round bottom flask, 50 mL of deionized water was added, then 2.0 g of molybdenum disulfide powder was added, and then 3.0 mL of ethylenediamine was added under stirring at room temperature. The reaction mixture was continuously stirred at a stirring speed of 1000 rpm for 24 hours at room temperature, and then intermittently ultrasonicated for 5 days at room temperature to form ethylenediamine intercalated molybdenum disulfide flakes. The above ethylenediamine intercalated molybdenum disulfide flakes were transferred to a stainless steel autoclave, and the autoclave was placed in an oven and calcined at 130 °C for 14 hours. After the reaction was completed, a suspension containing molybdenum disulfide quantum dots was formed. 1.3, The above suspension containing molybdenum disulfide quantum dots was naturally cooled to room temperature, then centrifuged at a speed of 13000 rpm for 15 minutes, then the supernatant was pretreated with liquid nitrogen, and the pretreated supernatant was freeze-dried for three days. After adding 3 mL of deionized water to the obtained crude product, ultrasonic dispersion was carried out, and then the precipitate was collected by centrifugation at a speed of 18000 rpm for 60 minutes. The obtained purified solid was vacuum dried at room temperature for 30 hours, and finally molybdenum disulfide quantum dots were obtained.
[0059] Step 2, preparation of electrolyte.
[0060] 2.3060 g of prepared molybdenum disulfide quantum dots were added to 100 mL of deionized water for ultrasonic dispersion to prepare a suspension of molybdenum disulfide quantum dots at a concentration of 23.06 mg / mL.
[0061] Then 20 mL of the prepared suspension was measured, 0.815 mL of concentrated sulfuric acid was added, and deionized water was added to dilute to 30 mL, and then poured into the electrolysis cell.
[0062] In the electrolysis cell, glassy carbon electrode, platinum electrode and silver chloride electrode were assembled in sequence as working electrode, counter electrode and reference electrode, respectively, then pure argon gas was used to remove dissolved oxygen in the sealed system, and then copper sulfate solution obtained by dissolving 0.2394 g of copper sulfate in 2 mL of deionized water was added to the electrolysis cell.
[0063] The final prepared electrolyte has a concentration of 0.5 mol / L and 50 mmol / L of sulfuric acid and copper sulfate, respectively.
[0064] Step 3, preparation of quantum dot suspension loaded with gold monatomic atoms.
[0065] With a stirring speed of 1000 rpm, 0.150 V was selected as the underpotential deposition potential to load copper single atoms onto the surface of molybdenum disulfide quantum dots. The underpotential deposition process of copper single atoms was stopped when the cathode current stabilized and approached 0.
[0066] A 50 mmol / L sodium chloroaurate dihydrate and 50 mmol / L sulfuric acid solution, prepared by dissolving 0.5967 g of sodium chloroaurate dihydrate in 20 mL of deionized water, followed by the addition of 81.5 μL of concentrated sulfuric acid and diluting with deionized water to 30 mL, was added dropwise to an electrolytic cell. The reaction solution was then subjected to a chemical displacement reaction at room temperature with stirring at 1600 rpm. After 8 hours, a suspension of molybdenum disulfide quantum dots loaded with gold single atoms was formed.
[0067] Step 4: Obtain molybdenum disulfide quantum dots loaded with gold single atoms.
[0068] The above-mentioned molybdenum disulfide quantum dot suspension loaded with gold single atoms was subjected to vacuum filtration, and then the filtrate was pretreated with liquid nitrogen to obtain a pretreated filtrate. After freeze-drying the pretreated filtrate for three days, the dried crude product was obtained.
[0069] Add 3 mL of deionized water to the dried crude product and disperse it by ultrasonication. Then, centrifuge the precipitate at 18,000 rpm for 60 minutes and collect it to obtain the purified solid.
[0070] The purified solid was vacuum dried at room temperature for 30 hours to finally obtain molybdenum disulfide quantum dots supported on gold single atoms.
[0071] like Figure 4 As shown in Comparative Example 1, the fluorescence intensity of molybdenum disulfide quantum dots loaded with gold single atoms is significantly higher than that of molybdenum disulfide quantum dots. This phenomenon is because after modifying the surface of molybdenum disulfide quantum dots with gold single atoms, the p-type doping of gold introduces a new defect energy level in the band gap of molybdenum disulfide. This defect level can capture excess electrons in the conduction band of n-type molybdenum disulfide, thereby passivating the non-radiative surface states. This increases the recombination probability between conduction band electrons and valence band holes in molybdenum disulfide, leading to enhanced fluorescence efficiency. Compared with Comparative Example 1, the preparation method of this application has advantages such as lower cost, simpler operation, shorter preparation process, and simpler post-processing, and the prepared quantum dot material exhibits superior fluorescence performance. Based on the experimental conclusions of Comparative Example 1, we speculate that loading gold single atoms into the zinc-lead-copper sulfide quaternary quantum dots prepared in this application may further enhance their fluorescence intensity, thus preparing quantum dot materials with even better fluorescence performance.
[0072] Comparative Example 2: This comparative example 2 provides a method for preparing a cadmium sulfide quantum dot loaded with a single gold atom; Comparative Example 2 differs from Example 1 in that the steps are: Step 1, Preparation of cadmium sulfide quantum dots.
[0073] 1.1, Dissolve 2.2835 g of cadmium chloride dihydrate in 25 mL of deionized water to form a homogeneous cadmium precursor solution; dissolve 2.4018 g of sodium sulfide nonahydrate in 8 mL of deionized water to form a homogeneous sulfur precursor solution; dissolve 0.7715 g of mercaptoethylamine in 5 mL of deionized water to form a homogeneous solution of mercaptoethylamine; 1.2, Add the above-mentioned cadmium precursor solution and mercaptoethylamine solution into a 250 mL round-bottom flask in sequence, and dilute with deionized water to 50 mL, then remove dissolved oxygen in the sealed system with pure argon, and then heat the reaction solution at 40°C under stirring at 1000 rpm for 30 minutes, during which the pH value of the reaction solution is adjusted to about 3 with 1 mol / L dilute hydrochloric acid; 1.3, Rapidly add the above-mentioned sulfur precursor solution to the above-mentioned reaction solution, and continue to heat the reaction solution at 110°C under stirring at 1000 rpm for 5 hours under the continuous protection of pure argon, and after the reaction is completed, a suspension containing cadmium sulfide quantum dots is formed and stored in a refrigerator at 4°C.
[0074] Step 2, Preparation of electrolyte.
[0075] Take 10 mL of the prepared suspension containing cadmium sulfide quantum dots, add 0.815 mL of concentrated sulfuric acid to it, and dilute with deionized water to 30 mL, and then pour into the electrolysis cell.
[0076] Assemble the glassy carbon electrode, platinum electrode and silver chloride electrode in sequence in the electrolysis cell as the working electrode, counter electrode and reference electrode respectively, then remove dissolved oxygen in the sealed system with pure argon, and then add copper sulfate solution obtained by dissolving 0.2394 g of copper sulfate in 2 mL of deionized water into the electrolysis cell.
[0077] The concentrations of sulfuric acid and copper sulfate in the finally prepared electrolyte are 0.5 mol / L and 50 mmol / L, respectively.
[0078] Step 3, Preparation of quantum dot suspension loaded with a single gold atom.
[0079] With a stirring speed of 1000 rpm, 0.100 V was selected as the underpotential deposition potential to load copper single atoms onto the surface of cadmium sulfide quantum dots. The underpotential deposition process of copper single atoms was stopped when the cathode current stabilized and approached 0.
[0080] A 50 mmol / L sodium chloroaurate dihydrate and 50 mmol / L sulfuric acid solution, prepared by dissolving 0.5967 g of sodium chloroaurate dihydrate in 20 mL of deionized water, followed by the addition of 81.5 μL of concentrated sulfuric acid and diluting with deionized water to 30 mL, was added dropwise to an electrolytic cell. The reaction solution was then subjected to a chemical displacement reaction at room temperature with stirring at 1600 rpm. After 8 hours, a suspension of cadmium sulfide quantum dots loaded with gold single atoms was formed.
[0081] Step 4: Obtain cadmium sulfide quantum dots loaded with gold single atoms.
[0082] The above-mentioned cadmium sulfide quantum dot suspension loaded with gold single atoms was subjected to vacuum filtration, and then the filtrate was pretreated with liquid nitrogen to obtain a pretreated filtrate. After freeze-drying the pretreated filtrate for three days, the dried crude product was obtained.
[0083] Add 3 mL of deionized water to the dried crude product and disperse it by ultrasonication. Then, centrifuge the precipitate at 18,000 rpm for 60 minutes and collect it to obtain the purified solid.
[0084] The purified solid was vacuum dried at room temperature for 30 hours to finally obtain gold single-atom-loaded cadmium sulfide quantum dots.
[0085] like Figure 5 As shown in Comparative Example 2, the fluorescence intensity of cadmium sulfide quantum dots loaded with gold single atoms is significantly higher than that of cadmium sulfide quantum dots. This phenomenon is because after modifying the surface of cadmium sulfide quantum dots with gold single atoms, an electron transfer process occurs from the cadmium sulfide quantum dots to the gold single atoms, which increases the recombination probability between conduction band electrons and valence band holes in the cadmium sulfide quantum dots. Simultaneously, this reduces the fluorescence lifetime of the cadmium sulfide quantum dots, thus enhancing the fluorescence efficiency. Compared with Comparative Example 2, the preparation method of this application has the advantages of lower cost and greater environmental friendliness. Furthermore, the prepared quantum dot material is non-biotoxic and exhibits superior fluorescence performance. Based on the experimental conclusions of Comparative Example 2, we speculate that loading gold single atoms into the zinc-lead-copper quaternary quantum dots prepared in this application may further enhance their fluorescence intensity, thereby preparing quantum dot materials with even better fluorescence performance.
[0086] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms, characterized in that, Includes the following steps: Preparation of zinc-lead-copper quaternary quantum dots; The zinc-lead-copper quaternary quantum dots are dispersed in an aqueous phase to form a quantum dot suspension; the quantum dot suspension is mixed with an acid source and brought to a constant volume, then poured into an electrolytic cell for deoxygenation treatment, and then a first copper source is added to prepare an electrolyte. Under constant potential conditions, copper single atoms are deposited on the surface of quantum dots in the electrolyte by underpotential deposition. Then, a mixture of gold source is added to the deposited electrolyte to carry out a chemical displacement reaction, thereby obtaining a quantum dot suspension loaded with gold single atoms. The quantum dot suspension loaded with gold single atoms was purified and dried to obtain zinc lead copper sulfide quaternary quantum dots loaded with gold single atoms.
2. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 1, characterized in that, The preparation method of the zinc-lead-copper quaternary quantum dots is as follows: Zinc source, sulfur source, lead source and second copper source were respectively mixed with water solvent to form homogeneous zinc precursor solution, sulfur precursor solution, lead precursor solution and copper precursor solution; Under the first stirring condition, the surface stabilizer is mixed with boiling water, and then the zinc precursor solution, sulfur precursor solution, lead precursor solution and copper precursor solution are added in sequence. The mixture is then heated and refluxed to form a suspension containing zinc, lead and copper sulfide quaternary quantum dots. After centrifuging, washing and drying the suspension containing zinc lead copper sulfide quaternary quantum dots, purified zinc lead copper sulfide quaternary quantum dots are obtained.
3. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 2, characterized in that, The zinc source includes zinc acetate dihydrate, the sulfur source includes sodium sulfide nonahydrate, the lead source includes lead acetate trihydrate, and the second copper source includes copper acetate monohydrate. The concentration of zinc in the zinc precursor solution, calculated as elemental zinc, is 250.0 mmol / L; The concentration of sulfur in the sulfur precursor solution, calculated as elemental sulfur, is 250.0 mmol / L; The concentration of lead in the lead precursor solution was 4.0 mmol / L. The concentration of copper in the copper precursor solution was 12.5 mmol / L.
4. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 2, characterized in that, The stirring speed under the first stirring condition is 900-1100 rpm; The surface stabilizer includes chitosan; The amount of boiling water added is 80-120 mL, and the temperature of the boiling water is 90-110 ℃; The molar ratio of zinc in the zinc precursor solution, sulfur in the sulfur precursor solution, lead in the lead precursor solution, and copper in the copper precursor solution is 62.5:62.5:1:3.
125. The molar ratio of zinc element to surface stabilizer in the zinc precursor solution is 10000:1; The heating temperature for the reflux reaction is 90-110 ℃, and the reaction time is 3-5 hours.
5. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 2, characterized in that, The centrifugation speed is 12,000-13,000 rpm, and the centrifugation time is 5-7 minutes. The washing solvent includes deionized water, and the washing is performed 3-4 times, with 8-12 mL of deionized water added each time. The drying process is vacuum drying at room temperature, and the drying time is 24-36 hours.
6. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 1, characterized in that, The concentration of zinc sulfide, lead, and copper quaternary quantum dots in the quantum dot suspension is 20-30 mg / mL. The acid source is a concentrated sulfuric acid solution, and the volume ratio of the quantum dot suspension to the acid source is 100:8-9; The electrolytic cell is equipped with a three-electrode system including a working electrode, a counter electrode, and a reference electrode, and an inert gas is introduced to create an oxygen-free environment, the inert gas including argon. The first copper source is a copper sulfate solution, and the molar ratio of the acid source to the first copper source in the electrolyte is 10:
1.
7. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 1, characterized in that, The underpotential deposition steps are as follows: Determine the constant potential as the potential for underpotential deposition; Copper single atoms are deposited on the surface of quantum dots in the electrolyte by underpotential deposition until the cathode current reaches a stable state and the value of the cathode current meets a preset current threshold, at which point the deposition stops. The constant potential is 0.05-0.15 V; the stirring speed of the underpotential deposition is 900-1100 rpm; and the reaction time of the underpotential deposition is 11-13 hours.
8. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 1, characterized in that, The gold source mixture comprises a mixed solution of sodium chloroaurate dihydrate and sulfuric acid, wherein the concentration of sodium chloroaurate dihydrate in the mixed solution is 50 mmol / L; and the concentration of sulfuric acid in the mixed solution is 50 mmol / L. The stirring speed for the chemical displacement reaction is 1500-1800 rpm, and the reaction time is 6-10 hours.
9. The method for preparing zinc-lead-copper quaternary quantum dots loaded with gold single atoms according to claim 1, characterized in that, The purification and drying steps are as follows: The quantum dot suspension loaded with gold single atoms was subjected to vacuum filtration to obtain a filtrate, which was then pretreated with liquid nitrogen to obtain a pretreated filtrate. The pretreated filtrate was freeze-dried to obtain the dried crude product. The dried crude product is redispersed in water or an organic solvent, and after a second centrifugation, a purified solid is obtained. The purified solid was vacuum dried at room temperature to obtain the final zinc lead copper sulfide quaternary quantum dots loaded with gold single atoms. The freeze-drying time is 24-36 hours. The rotation speed of the secondary centrifugation is 16,000-20,000 rpm, and the time of the secondary centrifugation is 50-80 minutes; The vacuum drying time is 24-36 hours.
10. A zinc-lead-copper quaternary quantum dot loaded with gold single atoms, characterized in that, It is prepared by the method for preparing zinc lead copper sulfide quaternary quantum dots loaded with gold single atoms as described in any one of claims 1-9.