A method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer

Abstract

This invention relates to a method for preparing gold nanoparticle cocatalysts using ultraviolet light-induced electron transfer, belonging to the field of nanocatalyst technology. The method involves adding sodium tungstate solution and a gold precursor solution to a methanol solution, followed by ultrasonic treatment to obtain a mixed solution. Under nitrogen atmosphere, the reaction is induced by ultraviolet light irradiation for 5–10 min. Solid-liquid separation is then performed, and the solid is vacuum dried to obtain the gold nanoparticle cocatalyst. This invention utilizes the electron transfer process induced by sodium tungstate and ultraviolet light to reduce the gold precursor solution into gold nanoparticles, which can be loaded onto a catalyst support and modified. The method allows for easy control of the size and loading of the metal cocatalyst, reducing the cost and difficulty of synthesizing similar materials, thus lowering costs. Furthermore, no toxic or harmful chemicals or reagents are introduced into the system, reducing environmental pollution.

Description

Technical Field

[0001] This invention relates to a method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer, belonging to the field of nanocatalyst technology. Background Technology

[0002] Metal nanoparticles, especially gold nanoparticles (Au NPs), play a crucial role in catalysis due to their unique physicochemical properties. These nanoparticles exhibit catalytic performance distinct from bulk metals due to their small size and large specific surface area. Au NPs are particularly adept at catalyzing certain chemical reactions at low temperatures, making them important for applications in environmental protection and green chemistry. Au NPs demonstrate excellent catalytic performance in a variety of chemical reactions, such as oxidation, reduction, and organic synthesis. They show broad application prospects in environmental remediation (e.g., waste gas treatment), pharmaceutical synthesis, and energy conversion (e.g., fuel cells).

[0003] Currently, the main challenges in synthesizing AuNPs are concentrated in the following aspects: First, precise control of size and shape is crucial. The catalytic performance, optical properties, and biocompatibility of gold nanoparticles are closely related to their size and shape, making precise control of these parameters a significant challenge. Second, purity and consistency are critical. Impurities, such as byproducts or unreacted starting materials, may be generated during synthesis, affecting nanoparticle performance. Ensuring high purity and consistency in the synthesized nanoparticles is essential. Third, environmental impact and safety must be considered. Some methods for synthesizing AuNPs may involve toxic chemicals or generate harmful byproducts, posing threats to the environment and operator safety. Developing more environmentally friendly synthesis methods is currently a research hotspot. Finally, synthesis cost is a concern: some efficient synthesis methods may be expensive, limiting their widespread use in certain applications. Reducing synthesis costs while maintaining high nanoparticle quality is key to their commercialization.

[0004] Currently, the main methods for preparing Au NPs include: chemical reduction, which uses reducing agents (such as citric acid, sodium borohydride, etc.) to reduce gold precursors into gold nanoparticles in solution; however, this method may produce byproducts and requires careful selection of the reducing agent. In addition, there are reports of obtaining Au NPs through physical methods, such as high-energy physical processes (e.g., laser evaporation). However, while this method allows for control over the size and distribution of nanoparticles, it is costly and faces challenges in large-scale production. Therefore, developing easily controllable and low-cost methods for preparing Au NPs is of great significance. Summary of the Invention

[0005] To address the current challenges in preparing gold nanoparticle cocatalysts, this invention proposes a method for preparing gold nanoparticle cocatalysts using ultraviolet light-induced electron transfer. Specifically, under ultraviolet light irradiation, the gold precursor is reduced to metal nanoparticles through an electron transfer process using sodium tungstate solution, resulting in nanoparticles with a size of 10–50 nm. These nanoparticles exhibit extremely high surface area to volume ratio, reactivity, and atom utilization.

[0006] A method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer includes the following specific steps:

[0007] (1) Sodium tungstate powder and ethylene glycol were added to deionized water and dissolved by ultrasonication to obtain sodium tungstate solution;

[0008] (2) The gold precursor was ultrasonically dissolved in deionized water to obtain a gold precursor solution;

[0009] (3) Add sodium tungstate solution and gold precursor solution to methanol solution, sonicate to obtain mixed solution, irradiate with ultraviolet light under nitrogen conditions for 5-10 min to induce reaction, separate solid and liquid, and vacuum dry the solid to obtain gold nanoparticle co-catalyst.

[0010] In step (1), the concentration of sodium tungstate in the sodium tungstate solution is 10-30 g / L, and the amount of ethylene glycol added is 10-15% of the volume of deionized water.

[0011] In step (2), the gold precursor is chloroauric acid, and the concentration of the gold precursor solution is 5-10 g / L.

[0012] The methanol solution in step (3) is a methanol-deionized aqueous solution with a methanol mass concentration of 5-10%.

[0013] In step (3), the molar ratio of sodium tungstate to gold precursor is 2-6:3, and the volume ratio of sodium tungstate solution to methanol solution is 1-3:25.

[0014] The ultraviolet light wavelength in step (3) is 315-400nm.

[0015] The beneficial effects of this invention are:

[0016] (1) In the absence of toxic and harmful drugs, the present invention utilizes the electron transfer process of sodium tungstate solution under ultraviolet light to reduce gold precursors into metal nanoparticles, thereby preparing nanoparticles with a size of 10-50 nm, which have extremely high surface area to volume ratio, reactivity and atom utilization; they can be used as catalysts for electrocatalysis, thermocatalysis and photocatalysis reactions.

[0017] (2) The method for preparing gold nanoparticle cocatalysts in this invention is simple, has low equipment requirements, and low cost. Attached Figure Description

[0018] Figure 1 This is a high-angle annular dark-field scanning transmission (HAADF-STEM) image of the gold nanoparticle co-catalyst in Example 1.

[0019] Figure 2 The image shows the X-ray energy dispersive X-ray spectroscopy (EDX) spectrum of the gold nanoparticle cocatalyst in Example 1.

[0020] Figure 3 X-ray photoelectron spectroscopy (XPS) of gold nanoparticle cocatalyst in Example 1;

[0021] Figure 4 This is a comparison of the ORR photocatalytic performance of g-C3N4 supported by gold nanoparticles and g-C3N4 without support in Example 1.

[0022] Figure 5 This is a high-angle annular dark-field scanning transmission (HAADF-STEM) image of the gold nanoparticle co-catalyst in Example 2.

[0023] Figure 6 The image shows the X-ray energy dispersive X-ray spectroscopy (EDX) spectrum of the gold nanoparticle cocatalyst in Example 2.

[0024] Figure 7 This is a high-angle annular dark-field scanning transmission (HAADF-STEM) image of the gold nanoparticle co-catalyst in Example 3.

[0025] Figure 8 The image shows the X-ray energy dispersive X-ray spectroscopy (EDX) spectrum of the gold nanoparticle cocatalyst in Example 3. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0027] Example 1: A method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer, the specific steps of which are as follows:

[0028] (1) Sodium tungstate powder and ethylene glycol are added to deionized water and dissolved by ultrasonication to obtain sodium tungstate solution; wherein the concentration of sodium tungstate in sodium tungstate solution is 20 g / L and the amount of ethylene glycol added is 10% of the volume of deionized water.

[0029] (2) The gold precursor (chloroauric acid) was ultrasonically dissolved in deionized water to obtain a chloroauric acid solution; wherein the concentration of the chloroauric acid solution was 10 g / L;

[0030] (3) Sodium tungstate solution and chloroauric acid solution were added to methanol-deionized water solution and ultrasonically treated to obtain a mixed solution. The mixed solution was placed in an ultraviolet light system and irradiated with ultraviolet light (wavelength 315-400nm) at 35% power for 5 min under nitrogen conditions to induce the reaction. The solid and liquid were separated, and the solid was washed 5 times with deionized water and then vacuum dried at 60℃ to obtain gold nanoparticle co-catalyst. The methanol-deionized water solution contained 5% methanol by mass, the molar ratio of sodium tungstate to chloroauric acid was 2:3, and the volume ratio of sodium tungstate solution to methanol solution was 1:25.

[0031] The high-angle annular dark-field scanning transmission (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDX) images of the gold nanoparticle co-catalyst in this embodiment are shown below. Figure 1 and Figure 2 ,from Figure 1 and 2 It can be seen that the average size of the Au nanoparticles is approximately 10 nm, and the X-ray energy dispersive spectroscopy (XPS) information of Au element corresponds strictly with the morphological information. The X-ray photoelectron spectroscopy (XPS) of the gold nanoparticle co-catalyst is shown in [reference needed]. Figure 3 This indicates that Au nanoparticles were successfully prepared in this embodiment;

[0032] The co-catalytic effect of Au nanoparticles on photocatalysts was evaluated by loading them onto a graphitic carbon nitride substrate (g-C3N4) using a wet chemical method. The loading amount of Au nanoparticles on g-C3N4 was 5% (mass fraction). O2-saturated deionized water was used as the reaction solution, with unloaded g-C3N4 as the activity control. A xenon lamp light source with a wavelength ≥ 420 nm and a light intensity of 50 mW / cm² was used. -2 The ORR photocatalytic performance comparison between Au nanoparticles-supported g-C3N4 and unsupported g-C3N4 prepared in this example is shown in the figure below. Figure 4 ,from Figure 4 It can be seen that the ORR photocatalytic production of H2O2 by Au nanoparticles supported on g-C3N4 and unsupported g-C3N4 prepared in this example reached 192 μmol L⁻¹ at 60 min, respectively. -1 and 14 μmol L -1 This indicates that the Au nanoparticle cocatalyst prepared in this embodiment has high cocatalytic activity.

[0033] Example 2: A method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer, the specific steps of which are as follows:

[0034] (1) Sodium tungstate powder and ethylene glycol are added to deionized water and dissolved by ultrasonication to obtain sodium tungstate solution; wherein the concentration of sodium tungstate in sodium tungstate solution is 20 g / L and the amount of ethylene glycol added is 12% of the volume of deionized water.

[0035] (2) The gold precursor (chloroauric acid) was ultrasonically dissolved in deionized water to obtain a chloroauric acid solution; wherein the concentration of the chloroauric acid solution was 10 g / L;

[0036] (3) Sodium tungstate solution and chloroauric acid solution were added to methanol-deionized water solution and ultrasonically treated to obtain a mixed solution. The mixed solution was placed in an ultraviolet light system and irradiated with ultraviolet light (wavelength 315-400nm) at 35% power for 8 minutes under nitrogen conditions. Solid-liquid separation was performed, and the solid was washed 6 times with deionized water and then vacuum dried at 65℃ to obtain gold nanoparticle co-catalyst. The methanol-deionized water solution contained 5% methanol by mass, the molar ratio of sodium tungstate to chloroauric acid was 4:3, and the volume ratio of sodium tungstate solution to methanol solution was 2:25.

[0037] The high-angle annular dark-field scanning transmission (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDX) images of the gold nanoparticle co-catalyst in this embodiment are shown below. Figure 5 and 6 ,from Figure 5 and 6 It can be seen that the average size of Au nanoparticles is about 30 nm, and the X-ray energy spectrum information of Au element corresponds strictly with the morphology information. The Au nanoparticles were tested by X-ray photoelectron spectroscopy (XPS) using the same method as in Example 1, which shows that Au nanoparticles were successfully prepared in this example.

[0038] The co-catalytic effect of the Au nanoparticles prepared in this example on the photocatalyst was evaluated using the same method as in Example 1. The photocatalytic H2O2 production performance of the Au nanoparticles supported on g-C3N4 and the unsupported g-C3N4 at 60 min was 187 μmol / L, respectively. -1 and 14 μmol L -1 This indicates that the Au nanoparticle cocatalyst prepared in this embodiment has high cocatalytic activity.

[0039] Example 3: A method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer, the specific steps of which are as follows:

[0040] (1) Sodium tungstate powder and ethylene glycol are added to deionized water and dissolved by ultrasonication to obtain sodium tungstate solution; wherein the concentration of sodium tungstate in sodium tungstate solution is 20 g / L and the amount of ethylene glycol added is 15% of the volume of deionized water;

[0041] (2) The gold precursor (chloroauric acid) was ultrasonically dissolved in deionized water to obtain a chloroauric acid solution; wherein the concentration of the chloroauric acid solution was 10 g / L;

[0042] (3) Sodium tungstate solution and chloroauric acid solution were added to methanol-deionized water solution and ultrasonically treated to obtain a mixed solution. The mixed solution was placed in an ultraviolet light system and irradiated with ultraviolet light (wavelength 315-400nm) at 35% power for 10 min under nitrogen conditions. Solid-liquid separation was performed, and the solid was washed 4 times with deionized water and then vacuum dried at 70℃ to obtain gold nanoparticle co-catalyst. The methanol-deionized water solution contained 5% methanol by mass, the molar ratio of sodium tungstate to chloroauric acid was 6:3, and the volume ratio of sodium tungstate solution to methanol solution was 3:25.

[0043] The high-angle annular dark-field scanning transmission (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDX) images of the gold nanoparticle co-catalyst in this embodiment are shown below. Figure 7 and 8 ,from Figure 7 and 8 It can be seen that the average size of Au nanoparticles is about 50 nm, and the X-ray energy spectrum information of Au element corresponds strictly with the morphology information. The Au nanoparticles were tested by X-ray photoelectron spectroscopy (XPS) using the same method as in Example 1, which shows that Au nanoparticles were successfully prepared in this example.

[0044] The co-catalytic effect of the Au nanoparticles prepared in this example on the photocatalyst was evaluated using the same method as in Example 1. The photocatalytic H2O2 production performance of the Au nanoparticles supported on g-C3N4 and the unsupported g-C3N4 at 60 min was 189 μmol L⁻¹, respectively. -1 and 13 μmol L -1 This indicates that the Au nanoparticle cocatalyst prepared in this embodiment has high cocatalytic activity.

[0045] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing gold nanoparticle cocatalysts by ultraviolet light-induced electron transfer, characterized in that, The specific steps are as follows: (1) Sodium tungstate powder and ethylene glycol were added to deionized water and dissolved by ultrasonication to obtain sodium tungstate solution; (2) The gold precursor was ultrasonically dissolved in deionized water to obtain a gold precursor solution; (3) Add sodium tungstate solution and gold precursor solution to methanol solution, sonicate to obtain mixed solution, irradiate with ultraviolet light under nitrogen conditions for 5-10 min to induce reaction, separate solid and liquid, and vacuum dry the solid to obtain gold nanoparticle co-catalyst; the methanol solution is methanol-deionized aqueous solution, the methanol mass concentration in methanol solution is 5-10%; the molar ratio of sodium tungstate to gold precursor is 2-6:3, and the volume ratio of sodium tungstate solution to methanol solution is 1-3:

25.

2. The method for preparing gold nanoparticle co-catalysts by ultraviolet light-induced electron transfer according to claim 1, characterized in that: Step (1) The concentration of sodium tungstate in the sodium tungstate solution is 10~30g / L, and the amount of ethylene glycol added is 10~15% of the volume of deionized water.

3. The method for preparing gold nanoparticle co-catalysts by ultraviolet light-induced electron transfer according to claim 1, characterized in that: Step (2) The gold precursor is chloroauric acid, and the concentration of the gold precursor solution is 5~10g / L.

4. The method for preparing gold nanoparticle co-catalysts by ultraviolet light-induced electron transfer according to claim 1, characterized in that: Step (3) The ultraviolet light wavelength is 315~400nm.

Images