Method for enhancing interface heat transfer based on surface functionalized gold nanoparticles
Gold nanoparticles were prepared by citric acid reduction method and self-assembled single-molecular layer was modified. Combined with molecular dynamics simulation and Raman spectroscopy, the problem of lack of theoretical models in self-assembled single-molecular layer design was solved, and the precise optimization and enhancement of heat transfer in gold-water interface was achieved.
Patent Information
- Application Number
- CN202510510912.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2025-08-08
AI Technical Summary
The prior art lacks general theoretical models for designing and optimizing self-assembled single-molecular layers (SAMs), resulting in the inability to accurately predict and improve the interface thermal transfer performance between gold nanoparticles and liquids.
The citric acid reduction method was used to prepare gold nanoparticles, and the self-assembled single molecular layer containing thiol groups was modified through thiol replacement reaction, and combined with molecular dynamics simulation and Raman spectroscopy technology, the interface heat transfer performance was optimized.
Effective regulation and accurate prediction of interface heat transmission are achieved, and the thermal transmission performance of gold-water interface is enhanced.
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Figure CN120442224A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of nanoscience and technology, and in particular to a method for enhancing interface heat transfer based on surface functionalized gold nanoparticles. Background Art
[0002] Photothermal materials absorb light energy and convert it into heat. Metal nanoparticles have been shown to have excellent photothermal conversion efficiency, with gold nanoparticles being the most widely used. When exposed to light, gold nanoparticles absorb light energy through surface plasmon resonance and convert it into localized, high-intensity heat, thereby evaporating the surrounding liquid.
[0003] In recent years, gold nanoparticles (GNPs), thanks to their efficient photothermal conversion capabilities and tunable optical properties, have shown promising applications in wastewater treatment, seawater desalination, and solar energy utilization. However, during the gold-induced evaporation of liquids, interfacial thermal resistance plays a significant, and sometimes dominant, role in heat transfer. Therefore, regulating interfacial heat transfer between gold and water can fully exploit the photothermal effect of GNPs. Furthermore, the thermal transfer properties of gold and water are crucial for the application of GNPs.
[0004] To further improve evaporation efficiency, researchers have also combined gold nanoparticles with other nanostructures (such as nanoporous materials, carbon-based materials, and MXenes) to form composite materials. These composite materials can fully exploit the photothermal effect of gold nanoparticles. Surface functionalization of gold nanoparticles is also a common strategy for enhancing interfacial heat transport. In recent years, researchers have used self-assembled monolayers (SAMs) to functionalize gold particles to enhance heat transport at solid-liquid interfaces. However, studies have found that factors such as interfacial adhesion energy, SAM length, the structure of SAM terminal functional groups, and the degree of vibrational spectral coupling all affect thermal conductivity. It is generally believed that there is a positive correlation between interfacial adhesion energy and interfacial heat transport at solid-liquid interfaces. However, interfacial adhesion energy is a static property that cannot be directly linked to thermal conductivity, and experimental devices and techniques are lacking to study the impact of SAMs on interfacial heat transport. This results in a lack of universal theoretical models for the design of SAMs, making it difficult to accurately predict and optimize their thermal transport performance. Summary of the Invention
[0005] In view of the above-mentioned defects of the prior art, the present invention provides a method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles, comprising the following steps: (1) Preparation of gold nanoparticles by citric acid reduction synthesis; (2) Modifying the surface of gold nanoparticles with a thiol-containing self-assembled monolayer through a thiol replacement reaction; (3) Study the effect of self-assembled monolayers on heat transfer at the gold-water interface through molecular dynamics simulations; (4) Based on machine learning and non-equilibrium dynamics simulation, physical descriptor formulas are derived and used as screening criteria for the design of self-assembled monolayers; (5) Raman detection laser is used to excite the Raman signal of the self-assembled monolayer on the gold surface, and Raman spectroscopy is used to study the interfacial heat transfer and optimize the heat transfer performance.
[0006] Preferably, in step (1), the citric acid reduction synthesis method comprises the following steps: preparing chloroauric acid solution and sodium citrate solution; heating the chloroauric acid solution to the reaction temperature, then adding the sodium citrate solution, mixing and reacting; the color of the solution gradually changes from light yellow to purple or wine red, collecting and purifying the product to obtain gold nanoparticles.
[0007] Further preferably, the concentration of the chloroauric acid solution is 0.5 mM; the concentration of the sodium citrate solution is 0.5~5 mM.
[0008] More preferably, the reaction temperature is 100° C. and the reaction time is 10-15 min.
[0009] Preferably, in step (1), the particle size of the gold nanoparticles is 20-50 nm.
[0010] Preferably, in step (2), the thiol replacement reaction comprises the following steps: adding a thiol compound as a raw material for the self-assembled monolayer in a solution environment; obtaining a stable modified layer through the thiol replacement reaction; removing unbound thiol molecules by centrifugation, and resuspending with an ethanol or water mixture to ensure that the modification is complete.
[0011] More preferably, the thiol replacement reaction is stirred at room temperature or ultrasonic-assisted, and allowed to stand at 4-25° C. for 24-48 hours to obtain a stable modification layer.
[0012] Preferably, in step (2), the raw material of the self-assembled monolayer includes one of 1-hexanethiol, 6-mercapto-1-hexanol, and 6-mercaptohexanoic acid.
[0013] Preferably, in step (3), heat transfer at the gold-water interface is simulated by non-equilibrium molecular dynamics.
[0014] Preferably, in step (5), the wavelength of the Raman detection laser is 532 nm, and the power of the laser is 1.0-15 mW.
[0015] Based on the above technical solutions, the design concept and principle of the present invention are as follows: Gold nanoparticles are prepared using a citric acid reduction synthesis method, and organic self-assembled monolayers of different groups are modified on the surface of the gold nanoparticles through a thiol displacement reaction. In the surface-functionalized gold nanoparticles, due to the action of electrostatic forces, the hydrophilic SAM will attract water molecules closer to the solid surface. Through the synergistic effect of electrostatics and Lennard-Jones, a greater effective force is generated at the interface, thereby enhancing interfacial heat transfer. The present invention uses non-equilibrium molecular dynamics simulations to study the effect of SAM on heat transfer at the gold-water interface. Through machine learning and high-throughput non-equilibrium molecular dynamics simulations, the importance of each feature in the optimized physical descriptor in the design of SAMs with high interfacial thermal conductivity is analyzed to study the screening criteria for SAM design. Combined with Raman spectroscopy, the effect of SAM on interfacial heat transfer is studied. The method of the present invention prepares surface-functionalized gold nanoparticles, enhances interfacial heat transfer between gold and water, accurately predicts and optimizes the heat transfer performance of SAMs, and achieves effective regulation of interfacial heat transfer.
[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: This paper provides a method for enhancing interfacial heat transfer based on surface-functionalized gold nanoparticles. This method utilizes the surface plasmon resonance effect of gold nanoparticles, using the gold particles as nanohotspots. Simultaneously, surface functionalization enhances interfacial heat transfer. Non-equilibrium molecular dynamics simulations clarify the mechanism by which self-assembled monolayers enhance interfacial heat transfer. Based on machine learning, a formula is selected as a screening criterion for the design of self-assembled monolayers. Raman spectroscopy is also used to investigate the effect of self-assembled monolayers on interfacial heat transfer. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a model of bubble dynamics around heated nanoparticles; Figure 2 This is a schematic diagram of the synthesis principle of 1-hexanethiol self-assembled monolayer modified on the surface of gold particles; Figure 3 Scanning electron microscope (SEM) images of gold particles surface modified with -OH (left) and -COOH (right); Figure 4 It is the distribution diagram of interfacial thermal conductivity (ITC) of different SAMs under the action of interfacial binding energy.
[0018] Figure 5 are the contributions of electrostatic interaction and Lennard-Jones (LJ) interaction to the interfacial thermal conductivity (a) and interfacial adhesion energy (b). DETAILED DESCRIPTION
[0019] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.
[0020] Example 1 A method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles, comprising the following steps: (1) Gold nanoparticles were prepared by citric acid reduction method, with the particle size controlled at 20-50 nm; The specific process is as follows: prepare a 0.5 mM chloroauric acid solution and a 0.5-5 mM sodium citrate solution (adjusted according to particle size; a high concentration results in small particles, while a high concentration results in large particles). Pour 50 mL of the chloroauric acid solution into a three-necked flask and heat to 100°C under magnetic stirring. Rapidly add the sodium citrate solution and continue heating and stirring. React for 10-15 minutes until the solution color gradually changes from light yellow to purple or wine red, indicating successful formation of gold nanoparticles. Collect and purify the product to obtain gold nanoparticles. (2) 1-hexanethiol was modified on the surface of gold particles through thiol displacement reaction; The specific process is as follows: Take a gold nanoparticle solution and add an equimolar amount or an appropriate amount of a thiol compound; stir at room temperature or with ultrasound-assisted reaction, and let it stand at low temperature (4°C) for 24 hours to obtain a more stable modified layer; remove unbound thiol molecules by centrifugation (10,000 rpm, 10 minutes), and resuspend the solution in ethanol or water mixture 2-3 times to ensure complete modification. The resulting product is recorded as -CH3SAM; (3) Study the effect of self-assembled monolayers on heat transfer at the gold-water interface through molecular dynamics simulations; (4) Based on machine learning and non-equilibrium dynamics simulation, the mathematical formulas of the six Pareto fronts shown in Table 1 were derived and used as screening criteria for the design of self-assembled monolayers; Table 1: Mathematical formula of Pareto frontier
[0021] Where E represents the mean interfacial interaction energy, and L represents the average length of the SAM.
[0022] (5) The Raman signal of the self-assembled monolayer on the gold surface was excited by a Raman detection laser. The gold particles modified with the self-assembled monolayer were deposited on the quartz glass surface. The Raman detection laser (532 nm) was focused on the gold particles. The power of the Raman detection laser was adjusted in the range of 1.0 to 15 mW. Raman spectra were obtained at different powers. The interfacial heat transfer was studied by Raman spectroscopy to optimize the heat transfer performance.
[0023] Example 2 This example provides a method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles, which is basically the same as Example 1, except that 6-mercapto-1-hexanol is used to prepare a self-assembled monolayer in this example, and the resulting product is recorded as -OH SAM.
[0024] Example 3 This example provides a method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles, which is basically the same as Example 1, except that 6-mercaptohexanoic acid is used to prepare the self-assembled monolayer in this example, and the obtained product is recorded as -COOH SAM.
[0025] Example 4 This example, based on the particle properties obtained from the experiments in Examples 1 to 3, uses non-equilibrium molecular dynamics to study the enhancement effects of the above-mentioned different types of SAMs on interfacial heat transfer. To study the effects of different SAMs on interfacial heat transfer, the temperatures of gold particles modified with different SAMs in water were compared using Raman spectroscopy. The interfacial heat transfer between gold and water was indirectly reflected by comparing the temperature rise at the same power. To study the changes in interfacial heat transfer from the liquid phase to the gas phase with different SAMs, the temperature changes of gold particles modified with different SAMs during the process of moving from the liquid phase to the gas phase were compared using Raman spectroscopy. The changes in interfacial heat transfer between gold-water and gold-air were reflected by comparing the temperature-power coefficient.
[0026] In order to improve the heat transfer efficiency at the solid-liquid interface, the present invention modifies the surface of gold nanoparticles with SAM, thereby enhancing the heat transfer performance of the gold-water interface. Gold nanoparticles have a unique plasma resonance effect, which can efficiently absorb light energy and quickly convert it into heat energy, thereby forming a local high-temperature heat source under light conditions. Under laser irradiation, stimulated by light, plasma resonance is generated on the surface of the gold nanoparticles, which can significantly heat a thin layer around the nanoparticles and evaporate the surrounding liquid. The vaporized liquid carries away most of the heat obtained by the photothermal conversion of the gold nanoparticles. In this way, even when the overall temperature of the liquid is below the boiling point, the liquid near the nanoparticles can still vaporize to produce local steam. Figure 1 A model of the vapor layer generated around heated nanoparticles is shown.
[0027] Interfacial binding energy is generally considered a key factor influencing interfacial heat transport, with stronger interfacial binding energy having a positive impact on interfacial heat transport. Appropriate functionalization of the metal nanoparticle surface with the various SAMs described above can achieve different bonding mechanisms (including van der Waals forces and hydrogen bonds) at the solid-liquid interface, enhancing the thermal conductivity between the metal and water. Simultaneously, heat transport at the solid-liquid interface is also governed by vibrational spectral coupling. SAMs can act as a bridge between gold nanoparticles and liquids, and the similar vibrational spectra of gold nanoparticles and liquids enhance interfacial heat transport. Furthermore, SAMs with molecular defects promote bubble nucleation at the solid-liquid interface, allowing evaporation and more efficient heat removal from heated gold nanoparticles.
[0028] Example 5 In this example, scanning electron microscopy, ultraviolet-visible absorption spectroscopy (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the SAM modified with the gold nanoparticles. Figure 2 A schematic diagram of the synthesis principle of 1-hexanethiol SAM modified on the surface of gold particles in Example 1 is given. Figure 3 The SEM images of gold particles surface modified with -OH and -COOH are shown respectively.
[0029] Figure 4 The synthesis principle diagram of the gold particle surface modified 1-hexanethiol SAM in Example 1 is given. The synthesis principles of other SAMs are the same.
[0030] Figure 5 The distribution of interfacial thermal conductivity of different SAMs as a function of interfacial binding energy is shown, where Cp is the Pearson (linear) correlation coefficient. Based on nonequilibrium molecular dynamics, a positive correlation between interfacial binding energy and interfacial heat transport was observed.
[0031] To understand the underlying mechanism, the interfacial heat flux is characterized based on atomic velocities and interfacial forces. The interfacial interactions and heat transport are decomposed into contributions from Lennard-Jones and electrostatic forces, and their effects on the interatomic distances between SAM head groups and water molecules are linked to the interfacial heat transport. Figure 5The contributions of electrostatic and LJ interactions to interfacial thermal conductivity and interfacial adhesion energy are demonstrated. The results indicate a synergistic effect between the electrostatic and repulsive components of the LJ interaction. Electrostatic interactions exist between the hydrophilic functional groups of the SAM and water. The hydrophilic groups attract water molecules closer to the solid surface, resulting in a greater effective force at the interface from both electrostatic and repulsive interactions, leading to greater interfacial heat transfer.
[0032] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.
Claims
1. A method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles, characterized in that: The steps include: (1) Preparation of gold nanoparticles by citric acid reduction synthesis; (2) Modifying the surface of gold nanoparticles with a thiol-containing self-assembled monolayer through a thiol replacement reaction; (3) Study the effect of self-assembled monolayers on heat transfer at the gold-water interface through molecular dynamics simulations; (4) Based on machine learning and non-equilibrium dynamics simulation, physical descriptor formulas are derived and used as screening criteria for the design of self-assembled monolayers; (5) Raman detection laser is used to excite the Raman signal of the self-assembled monolayer on the gold surface, and Raman spectroscopy is used to study the interfacial heat transfer and optimize the heat transfer performance.
2. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 1, characterized in that: In step (1), the citric acid reduction synthesis method includes the following steps: preparing chloroauric acid solution and sodium citrate solution; heating the chloroauric acid solution to the reaction temperature, then adding the sodium citrate solution, mixing and reacting; the color of the solution gradually changes from light yellow to purple or wine red, collecting and purifying the product to obtain gold nanoparticles.
3. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 2, characterized in that: The concentration of the chloroauric acid solution is 0.5 mM; the concentration of the sodium citrate solution is 0.5-5 mM.
4. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 2, wherein: The reaction temperature is 100°C and the reaction time is 10-15 min.
5. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 1, wherein: In the step (1), the particle size of the gold nanoparticles is 20-50 nm.
6. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 1, characterized in that: In step (2), the thiol replacement reaction comprises the following steps: adding a thiol compound as a raw material for the self-assembled monolayer in a solution environment; obtaining a stable modified layer through the thiol replacement reaction; removing unbound thiol molecules by centrifugation, and resuspending with an ethanol or water mixture to ensure that the modification is complete.
7. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 6, characterized in that: The thiol replacement reaction is stirred at room temperature or ultrasonic-assisted, and allowed to stand at 4-25° C. for 24-48 hours to obtain a stable modification layer.
8. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 1, characterized in that: In the step (2), the raw material of the self-assembled monolayer includes one of 1-hexanethiol, 6-mercapto-1-hexanol, and 6-mercaptohexanoic acid.
9. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 1, characterized in that: In the step (3), heat transfer at the gold-water interface is simulated by non-equilibrium molecular dynamics.
10. The method for enhancing interfacial heat transfer based on surface functionalized gold nanoparticles according to claim 1, characterized in that: In step (5), the wavelength of the Raman detection laser is 532 nm, and the power of the laser is 1.0-15 mW.