Core-shell structure gold-copper at silver sulfide / copper sulfide photocatalytic colloidal material, and preparation method and application of core-shell structure gold-copper at silver sulfide / copper sulfide photocatalytic colloidal material

Abstract

The invention discloses a preparation method of a gold copper at silver sulfide / copper sulfide photocatalytic colloidal material with a core-shell structure, and the preparation method specifically comprises the following steps: adding CTAC, AgNO3 and an L-ascorbic acid solution into a gold copper nano-alloy precursor, and transferring the mixture into a vacuum oven for heat preservation to obtain a gold copper at silver solution; adjusting the pH value of the gold-copper-silver solution by using a NaOH solution, adding TAA, stirring, adding CTAB, HDA, L-ascorbic acid, TAA and copper nitrate into the gold-copper-silver sulfide solution, uniformly stirring, and transferring the mixture into a vacuum drying oven for heat preservation; and washing, centrifuging, and dispersing in deionized water. The AuCu-coated Ag2S / CuS photocatalytic colloid material with the core-shell structure prepared by the invention has the characteristics of high photocatalytic hydrogen production efficiency, high photon-generated carrier separation efficiency and high visible light absorption, can show excellent photocatalytic activity, and shows a good application prospect in the aspect of hydrogen production by photocatalytic full water splitting.

Description

Technical Field

[0001] This invention belongs to the field of metal photocatalytic material preparation technology, specifically relating to a method for preparing a core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material, and also relating to the gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material and its applications. Background Technology

[0002] Photocatalytic hydrogen production technology boasts significant advantages such as being green, sustainable, and having low raw material costs, making it an important component of the clean energy system. However, its large-scale application faces bottlenecks due to low photocatalytic efficiency and poor stability. As the core of this technology, the selection, design, and preparation of photocatalytic materials are crucial, directly determining their final performance and applications. Among numerous photocatalysts, metals with significant localized surface plasmon resonance (LSPR) effects, when used as substrates and modified with semiconductor nanomaterials, exhibit significantly improved hot electron and hot hole separation efficiency at the semiconductor interface compared to traditional metal-semiconductor composite systems. Furthermore, hot holes can directly participate in the reaction without the need for an external field or hole collection layer.

[0003] Compared to metal oxides, metal sulfides typically exhibit wider spectral response ranges and superior electron transport properties. In photocatalytic materials research, narrow-bandgap semiconductors have become a research hotspot due to their excellent carrier migration characteristics. As a typical narrow-bandgap metal sulfide, copper sulfide is a relatively common multivalent copper ion semiconductor photocatalyst. CuS is commonly found in the hexagonal crystal system and has a layered structure (Cu... + and Cu 2+ (Coexistence), which is beneficial for charge transport. The band gap is 1.5–2.2 eV, and the conduction band (CB) is located at -0.5 eV (vs. NHE), which can drive H. + Copper sulfide is reduced to produce H2, with a valence band (VB) position of +1.5 eV (vs. NHE), and can oxidize H2O or organic matter. Although copper sulfide has advantages such as being non-toxic, abundant, low-cost, able to absorb visible light, and having high conductivity, it still has drawbacks such as a high photo-electron-hole recombination rate and severe susceptibility to photocorrosion.

[0004] Ag₂S is a narrow bandgap semiconductor with a bandgap of approximately 0.9–1.1 eV. Its band structure allows it to form favorable band alignments with metal nanoparticles (heterojunctions or Schottky junctions), and the built-in electric field at the interface drives the directional separation of charge carriers. As a typical plasmon-enhanced carrier-selective blocking layer, Ag₂S selectively prevents electrons from transferring from the semiconductor's conduction band and transfers holes to its valence band. In plasmon systems, by decoupling electrons and holes and directionally extracting holes, the plasmon-enhanced photocatalytic efficiency is significantly improved. Summary of the Invention

[0005] The primary objective of this invention is to provide a method for preparing core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal materials, which improves the plasmon effect and directional separation of charge carriers in the photocatalytic materials, thereby exhibiting excellent photocatalytic activity.

[0006] A second objective of this invention is to provide a core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material.

[0007] A third objective of this invention is to provide a method for preparing core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal materials and their application in photocatalytic hydrogen production through total water splitting.

[0008] The technical solution adopted in this invention is a method for preparing core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal materials, specifically implemented according to the following steps: Step 1: Prepare gold-copper nano-alloy precursor; Step 2: Add hexadecyl ammonium chloride, AgNO3, and L-ascorbic acid solution to the gold-copper nanoalloy precursor, mix well, and transfer the mixture to a vacuum oven for heat preservation to obtain a gold-copper@silver solution; Step 3: Adjust the pH of the gold-copper@silver solution using NaOH solution, add thiothioamide (TAA), stir, and obtain the gold-copper@silver sulfide solution; Step 4: Add hexadecylammonium bromide, hexadecylamine, L-ascorbic acid, thiosulfate, and copper nitrate to the gold copper@silver sulfide solution, stir well, and transfer the mixture to a vacuum drying oven for heat preservation. Step 5: The mixture from Step 4 is centrifuged and washed several times with deionized water, and then dispersed in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

[0009] The invention is further characterized in that, Step 1 specifically involves: Step 1.1: Disperse hexadecylamine (HDA) in deionized water using ultrasonication to obtain an HDA solution with a concentration of 0.5~1.8 mol / L; the ultrasonic dispersion temperature is 30~70℃ and the ultrasonication time is 10~50 min. Step 1.2: Under stirring conditions, CuCl2 and HAuCl4 are added to the HDA solution in sequence. After mixing evenly, a glucose solution with a concentration of 0.8~1.2 mol / L is added. The mixture is then magnetically stirred at room temperature for 10~40 min at a speed of 400~800 r / min to obtain a mixed solution. Step 1.3: Transfer the mixture to an oil bath and keep it at 80-120℃ for 15-30 min. After washing several times by centrifugation with deionized water at a speed of 6000-10000 r / min for 5-20 min, disperse it in deionized water to obtain the gold-copper nano-alloy precursor.

[0010] In step 2, the heat preservation temperature is 50~100℃ and the heat preservation time is 2~6h.

[0011] In step 3, the pH of the gold-copper@silver solution is adjusted to 12 using a NaOH solution with a concentration of 0.5~2 mol / L.

[0012] In step 3, the stirring time is 1 to 4 hours and the stirring speed is 600 to 900 r / min.

[0013] In step 4, the stirring time is 10~30 min, the stirring speed is 600~900 r / min; the heat preservation temperature is 80~110℃, and the heat preservation time is 2~3 h.

[0014] In step 5, the centrifugation speed is 6000-10000 r / min, and the centrifugation time is 5-20 min.

[0015] The second technical solution adopted in this invention is a method for preparing gold-copper@silver sulfide / copper sulfide photocatalytic colloidal materials with core-shell structure.

[0016] The beneficial effects of this invention are: (1) This invention utilizes a hydrothermal method to construct core-shell structured AuCu@Ag2S / CuS photocatalytic materials. By introducing Ag2S into AuCu@CuS, a gold-copper@silver sulfide / copper sulfide photocatalytic material with a double shell is obtained. It has advantages such as wide availability of raw materials, low production cost, fewer experimental procedures, and simple operation, and is expected to achieve industrial production. (2) The core-shell structure AuCu@Ag2S / CuS photocatalytic colloidal material prepared by the present invention exhibits a uniformly branched pentagonal body shape. The uniform branching helps electrons to migrate quickly to the surface of the catalyst, significantly improving its carrier separation efficiency. At the same time, the sharp branching structure of the pentagonal body can generate a significant tip effect, forming an extremely strong local electric field at the end of the branch, significantly enhancing light absorption and the generation of photogenerated carriers, enhancing the LSPR effect, and making the catalytic efficiency higher.

[0017] (3) The core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material prepared in this invention introduces an Ag2S layer between the AuCu and CuS layers, which enables the directional separation of the migration of charge carriers and holes. As a typical charge carrier selective blocking layer material, the Ag2S layer can selectively prevent electrons from transferring from the conduction band of the semiconductor and transfer holes in the semiconductor to its valence band. (4) The core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material prepared by the present invention has the characteristics of high photocatalytic hydrogen production efficiency, high photogenerated carrier separation efficiency, high visible light absorption, and broad-spectrum light response. It can achieve full-band photocatalytic response from visible light to near-infrared (400-1100nm), showing excellent photocatalytic activity and good application prospects in photocatalytic water splitting for hydrogen production. Attached Figure Description

[0018] Figure 1 These are UV-Vis images of AuCu@Ag2S / CuS prepared in Example 1; Figure 2 This is a graph showing the photocatalytic hydrogen production rate of the materials prepared in Example 1 and Comparative Examples 1-2; Figure 3 This is a bar chart showing the photocatalytic hydrogen production rate of the materials prepared in Example 1 and Comparative Examples 1-2 within 3 hours; Figure 4 These are the photocatalytic hydrogen production rate curves of the materials prepared in Examples 3 and 4; Figure 5 The SEM images of AuCu prepared in Comparative Example 1 are shown in Figure 1 (I). Figure 6 The SEM images of AuCu prepared in Comparative Example 1 are shown in Part II. Figure 7 This is the SEM image of AuCu@Ag2S / CuS prepared in Example 1. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] The present invention relates to a core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material with the structural formula AuCu@Ag2S / CuS.

[0021] The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material of the present invention is specifically implemented according to the following steps: Step 1, preparing the gold-copper nano-alloy precursor; specifically: Step 1.1: Disperse hexadecylamine (HDA) in deionized water using ultrasonication at a temperature of 30-70°C for 10-50 min to obtain an HDA solution with a concentration of 0.5-1.8 mol / L. Step 1.2: Under vigorous stirring, CuCl2 and HAuCl4 are added sequentially to the HDA solution. After mixing evenly, a glucose solution with a concentration of 0.8~1.2 mol / L is added. The mixture is then magnetically stirred at room temperature for 10~40 min at a speed of 400~800 r / min to obtain a mixed solution. The mass ratio of CuCl2, HAuCl4, HDA solution, and glucose solution is 9:20:100:150.

[0022] Step 1.3: Transfer the mixture to an oil bath and keep it at 80-120℃ for 15-30 min. After washing several times by centrifugation with deionized water at a speed of 6000-10000 r / min for 5-20 min, disperse it in deionized water to obtain the gold-copper nano-alloy precursor. Step 2: Add hexadecyl ammonium chloride (CTAC), AgNO3, and L-ascorbic acid solution sequentially to the gold-copper nano-alloy precursor obtained in Step 1, mix well, and transfer the mixture to a vacuum oven for heat preservation at a temperature of 50~100℃ for 2~6 hours to obtain a gold-copper@silver solution. The mass ratio of AgNO3, gold-copper nano-alloy precursor, CTAC, and L-ascorbic acid solution is 3:30:100:100. Step 3: Adjust the pH of the gold-copper@silver solution from Step 2 to 12 using NaOH solution, add thiosulfate (TAA), and stir at room temperature for 1-4 hours at a speed of 600-900 r / min to obtain the gold-copper@silver sulfide solution. The concentration of the NaOH solution used is 0.5~2 mol / L.

[0023] Step 4: Add hexadecyl ammonium bromide (CTAB), hexadecylamine (HDA), L-ascorbic acid (L-AA), thiosulfamide (TAA), and copper nitrate (CuNO3) sequentially to the gold copper@silver sulfide solution obtained in Step 3. Stir until homogeneous for 10-30 min at a stirring speed of 600-900 r / min. Transfer the mixture to a vacuum drying oven and keep it at 80-110℃ for 2-3 h. Step 5: Wash the mixture from Step 4 several times by centrifugation with deionized water at a speed of 6000-10000 r / min for 5-20 min, and then disperse it in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

[0024] This invention utilizes a hydrothermal method to prepare core-shell structured AuCu@Ag2S / CuS photocatalytic materials through the chemical reaction of CuCl2, HAuCl4, AgNO3, TAA, and Cu(NO3)2 with a reducing agent and a surfactant at a specific temperature. The reaction mechanism is as follows: First, at room temperature, CuCl2 and HAuCl4 complex with HDA. Under high temperature and the action of the reducing agent glucose, AuCu alloy fivefold twins begin to gradually form, and branches begin to grow over time. Then, by adding a surfactant, Ag... + With Cu + The solution can uniformly coat the alloy surface, and the addition of TAA provides sulfidation. The solution provides an environment conducive to crystal growth and composite formation, ensuring high crystallinity and uniformity of the material. After the reaction is complete, the mixture is cooled to room temperature. Unreacted products and excess surfactants are removed by washing with water, yielding a core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material. The washing process must ensure complete removal of unreacted products and surfactants to obtain a pure photocatalytic material.

[0025] The microstructure of the photocatalytic colloidal material of this invention exhibits a pentapod morphology, primarily derived from the hydrothermal preparation process. The gold-copper mixture in the precursor not only acts as a reaction medium but also plays a crucial role in uniformly distributing the precursor, promoting the chemical reaction, and controlling the morphology of the product. In the early growth stages of nucleation and seed formation, the nanoparticles possess a quasi-spherical shape with a twinned structure, ultimately forming a core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material with uniform branching and shell distribution. This method provides an efficient and controllable pathway for the synthesis of photocatalytic materials, and is expected to play a significant role in the energy field.

[0026] The core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material prepared in this invention can achieve highly efficient total water splitting for hydrogen production under visible light. The narrow band gap characteristics of Ag2S and CuS (Ag2S is 1.0 eV, CuS is ~1.5-2.0 eV) give them strong absorption capabilities in the visible and even near-infrared regions, expanding the light utilization range. The AuCu alloy core further enhances visible light capture (especially in the 500-700 nm range) through the localized surface plasmon resonance (LSPR) effect, and improves the photogenerated carrier yield of Ag2S / CuS through hot electron injection or near-field enhancement. The Ag2S / CuS shell forms a type II heterojunction. The conduction band (CB) of CuS is more negative than that of Ag2S, and electrons tend to migrate to CuS; the valence band (VB) of Ag2S is more positive than that of CuS, and holes tend to migrate to Ag2S. This spatial separation effectively reduces electron-hole recombination.

[0027] Example 1 The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material of the present invention is specifically implemented according to the following steps: Step 1: According to the Cu atom number: Au atom number = 9:16, with a total solution volume of 5 mL, weigh 50 mg HDA and 3 mL of deionized water for ultrasonic dispersion. Then, add 0.2 mL of 100 mol / L CuCl2 solution and 1.4 mL of 25 mol / L HAuCl4 solution, followed by 0.4 mL of 1000 mol / L glucose solution. Stir magnetically at room temperature. Transfer the mixture to an oil bath and keep it at 100℃ for 30 min. After washing several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, the gold-copper nano-alloy precursor is obtained by re-dispersing it in deionized water.

[0028] Step 2: Add 1 mL of 100 mol / L CTAC solution, 0.05 mL of 100 mol / L AgNO3 solution, and 0.6 mL of 100 mol / L L-AA solution sequentially to the gold-copper nanoalloy precursor obtained in Step 1. Transfer the mixture to a vacuum drying oven and keep it at 60℃ for 4 h to obtain a gold-copper@silver solution. Step 3: Adjust the pH of the solution from Step 2 to 12, add 0.06 mL of 100 mol / L TAA solution, stir at room temperature for 2 hours at a speed of 900 r / min to obtain gold copper@silver sulfide. Step 4: Add 2 mL of 200 mol / L CTAB solution, 2 mL of 100 mol / L HDA solution, and 2 mL of 100 mol / L L-AA solution to the gold copper@silver sulfide solution in Step 3 in sequence. Then add 0.4 mL of TAA solution and 0.2 mL of Cu(NO3)2 solution. Mix the mixture magnetically for 30 min at a speed of 900 r / min. Transfer the mixture to a vacuum drying oven and keep it at 90℃ for 2 h. Step 5: Wash the solution from Step 4 several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, and then disperse it in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

[0029] Example 2 The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material of the present invention is specifically implemented according to the following steps: Step 1: According to the ratio of Cu atoms to Au atoms = 9:16, with a total solution volume of 10 mL, 100 mg of HDA and 6 mL of deionized water were weighed and ultrasonically dispersed. Under vigorous stirring, 0.4 mL of 100 mol / L CuCl2 solution and 2.8 mL of 25 mol / L HAuCl4 solution were added sequentially, followed by 0.8 mL of 1000 mol / L glucose solution and magnetic stirring at room temperature. The mixture was transferred to an oil bath and kept at 100℃ for 30 min. After washing several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, the gold-copper nano-alloy precursor was obtained by re-dispersing it in deionized water.

[0030] Step 2: Add 10 mL of 100 mol / L CTAC solution, 0.2 mL of 100 mol / L AgNO3 solution, and 3 mL of 100 mol / L L-AA solution sequentially to the gold-copper nanoalloy precursor obtained in Step 1. Transfer the mixture to a vacuum drying oven and keep it at 60℃ for 4 hours to obtain a gold-copper@silver solution. Step 3: Adjust the pH of the solution from Step 2 to 12, add 0.3 mL of 100 mol / L TAA solution, stir at room temperature for 2 hours at a speed of 900 r / min to obtain gold copper@silver sulfide. Step 4: Add 3 mL of 200 mol / L CTAB solution, 3 mL of 100 mol / L HDA solution, and 3 mL of 100 mol / L L-AA solution to the gold copper@silver sulfide solution in Step 3 in sequence. Then add 0.6 mL of 100 mol / L TAA solution and 0.3 mL of 100 mol / L Cu(NO3)2 solution. Mix the mixture magnetically for 30 min at a speed of 900 r / min. Transfer the mixture to a vacuum drying oven and keep it at 90℃ for 2 h. Step 5: Wash the solution from Step 4 several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, and then disperse it in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

[0031] Example 3 The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material of the present invention is specifically implemented according to the following steps: Step 1: According to the ratio of Cu atoms to Au atoms = 9:16, with a total solution volume of 15 mL, 150 mg of HDA and 9.1 mL of deionized water were weighed and ultrasonically dispersed. Under vigorous stirring, 0.6 mL of 100 mol / L CuCl2 solution and 4.3 mL of 25 mol / L HAuCl4 solution were added sequentially, followed by 1 mL of 100 mol / L glucose solution and magnetic stirring at room temperature. The mixture was transferred to an oil bath and kept at 100℃ for 30 min. After washing several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, the gold-copper nano-alloy precursor was obtained by re-dispersing it in deionized water.

[0032] Step 2: Add 10 mL of 100 mol / L CTAC solution, 0.2 mL of 100 mol / L AgNO3 solution, and 3 mL of 100 mol / L L-AA solution sequentially to the gold-copper nanoalloy precursor obtained in Step 1 and mix thoroughly. Transfer the mixture to a vacuum drying oven and keep it at 60℃ for 4 hours to obtain a gold-copper@silver solution. Step 3: Adjust the pH of the solution from Step 2 to 12, add 0.4 mL of 100 mol / L TAA solution, stir at room temperature for 2 hours at a speed of 900 r / min to obtain gold copper@silver sulfide. Step 4: Add 6 mL of 200 mol / L CTAB solution, 6 mL of 100 mol / L HDA solution, and 6 mL of 100 mol / L L-AA solution to the gold copper@silver sulfide solution in Step 3 in sequence. Then add 1.2 mL of 100 mol / L TAA solution and 0.6 mL of 100 mol / L Cu(NO3)2 solution. Mix thoroughly with magnetic stirring for 30 min at a speed of 900 r / min. Transfer the mixture to a vacuum drying oven and keep it at 90℃ for 2 h. Step 5: Wash the solution from Step 4 several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, and then disperse it in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

[0033] Example 4 The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material of the present invention is specifically implemented according to the following steps: Step 1: According to the ratio of Cu atoms to Au atoms = 9:16, with a total solution volume of 25 mL, 200 mg of HDA and 18 mL of deionized water were weighed and ultrasonically dispersed. Then, 0.8 mL of 100 mol / L CuCl2 solution and 5.7 mL of 25 mol / L HAuCl4 solution were added sequentially and mixed. Next, 1.5 mL of 1000 mol / L glucose solution was added and magnetically stirred at room temperature. The mixture was transferred to an oil bath and kept at 100℃ for 30 min. After washing several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, the gold-copper nano-alloy precursor was obtained by re-dispersing it in deionized water.

[0034] Step 2: Add 10 mL of 100 mol / L CTAC solution, 0.2 mL of 100 mol / L AgNO3 solution, and 3 mL of 100 mol / L L-AA solution sequentially to the gold-copper nanoalloy precursor obtained in Step 1. Transfer the mixture to a vacuum drying oven and dry at 60℃ for 4 h to obtain a gold-copper@silver solution. Step 3: Adjust the pH of the solution from Step 2 to 12, add 0.3 mL of 100 mol / L TAA solution, stir at room temperature for 2 h at a stirring speed of 900 r / min to obtain gold copper@silver sulfide. Step 4: Add 6 mL of 200 mol / L CTAB, 6 mL of 100 mol / L HDA solution, and 6 mL of 100 mol / L L-AA solution to the gold copper@silver sulfide solution in Step 3 in sequence. Then add 1.2 mL of 100 mol / L TAA solution and 0.6 mL of 100 mol / L Cu(NO3)2 solution. Transfer the mixture to a vacuum drying oven and keep it at 90℃ for 2 hours. Step 5: Wash the solution from Step 4 several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, and then disperse it in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

[0035] Comparative Example 1 The preparation of gold-copper@copper sulfide core-shell photocatalytic materials is carried out according to the following steps: Step 1: Weigh 150 mg HDA and 10 mL of deionized water and disperse them ultrasonically. While stirring vigorously, add 0.6 mL of 100 mol / L CuCl2 solution and 4 mL of 25 mol / L HAuCl4 solution sequentially. Then add 1 mL of 1000 mol / L glucose solution and stir magnetically at room temperature. Transfer the mixture to an oil bath and keep it at 100℃ for 30 min. Wash it several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min. The gold-copper nano-alloy precursor is then dispersed in deionized water.

[0036] Step 2: Add 5 mL of 200 mol / L CTAB, 5 mL of 100 mol / L HDA solution, and 5 mL of 100 mol / L L-AA solution to the gold-copper nano-alloy precursor in Step 1 in sequence. Then add 1.2 mL of 100 mol / L TAA solution and 0.6 mL of 100 mol / L Cu(NO3)2 solution. Mix the mixture magnetically for 30 min at a speed of 900 r / min. Transfer the mixture to a vacuum drying oven and keep it at 90℃ for 2 h. Step 3: Wash the solution from Step 2 several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, and then disperse it in deionized water to obtain the gold-copper@copper sulfide core-shell photocatalytic material.

[0037] Comparative Example 2 The preparation of gold-copper alloy photocatalytic materials is carried out according to the following steps: Step 1: Weigh 150 mg HDA and 10 mL of deionized water and disperse it ultrasonically. Mix 0.6 mL of 100 mol / L CuCl2 solution and 4 mL of 25 mol / L HAuCl4 solution under vigorous stirring. Then add 1 mL of 1000 mol / L glucose solution and stir magnetically at room temperature. Transfer the mixture to an oil bath and keep it at 100℃ for 30 min. Wash several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min. The gold-copper nano-alloy precursor is then dispersed in deionized water.

[0038] Step 2: The solution from Step 1 is washed several times by centrifugation with deionized water at a speed of 8000 r / min for 10 min, and then dispersed in deionized water to obtain the gold-copper alloy photocatalytic material.

[0039] Example 5 Figure 1The image shows the UV-Vis spectrum of the AuCu@Ag2S / CuS photocatalytic colloidal material. After growing an Ag shell on the gold-copper alloy precursor, the plasmon peak shifts to the left. After sulfidation and CuS growth, the plasmon peak range expands. The insertion of the carrier-selective blocking layer Ag2S shell can selectively prevent electron backpropagation while facilitating hole transport, thus significantly improving the charge separation efficiency and plasmon enhancement effect of AuCu / CuS. This confirms the successful preparation of this core-shell photocatalytic colloidal material.

[0040] Figure 2 and Figure 3 The figures show the photocatalytic hydrogen production rates and yield curves of the core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material and the comparative samples AuCu@CuS and AuCu, respectively, within 3 hours. It can be seen that under the same conditions, the photocatalytic hydrogen production rates of AuCu@Ag2S / CuS, AuCu@CuS, and AuCu within 3 hours are 905 μmol·g⁻¹, respectively. -1 565 μmol·g -1 and 107 μmol·g -1 The hydrogen production rates were 302 μmol·g. -1 ·h -1 189 μmol·g -1 ·h -1 and 36 μmol·g -1 ·h -1 The above results indicate that the core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material exhibits optimal photocatalytic activity and can effectively achieve photocatalytic total water splitting for hydrogen production. This is mainly due to the insertion of a selective blocking layer, Ag2S, into the material, which enables highly photogenerated carrier-hole directional separation and high visible light absorption.

[0041] Figure 4 The figures show the photocatalytic hydrogen production of the core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal materials obtained in Examples 3 and 4 within 3 hours. It can be seen that the photocatalytic hydrogen production of the core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal materials with different yields is relatively stable within 3 hours, and they hold promise for large-scale production and application.

[0042] Example 6 Figure 5 , Figure 6 and Figure 7The images show TEM images of the samples prepared in Comparative Example 1 and Example 1. All the prepared samples are pentapods. The core-shell structured AuCu@Ag2S / CuS photocatalytic colloidal material successfully coated with a CuS layer on the basis of the uniformly pentapod AuCu@Ag2S structure. The CuS layer of the obtained AuCu@Ag2S / CuS exhibits relatively uniform and regular characteristics with clear boundaries, which indicates that the structure is well controlled throughout the synthesis process.

Claims

1. A method for preparing core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal materials, characterized in that, The specific steps are as follows: Step 1: Prepare gold-copper nano-alloy precursor; Step 2: Add hexadecyl ammonium chloride, AgNO3, and L-ascorbic acid solution to the gold-copper nano-alloy precursor, mix well, and transfer the mixture to a vacuum oven for heat preservation to obtain a gold-copper@silver solution; Step 3: Adjust the pH of the gold-copper@silver solution using NaOH solution, add thiothioamide (TAA), stir, and obtain the gold-copper@silver sulfide solution; Step 4: Add hexadecylammonium bromide, hexadecylamine, L-ascorbic acid, thiosulfate, and copper nitrate to the gold copper@silver sulfide solution, stir well, and transfer the mixture to a vacuum drying oven for heat preservation. Step 5: The mixture from Step 4 is centrifuged and washed several times with deionized water, and then dispersed in deionized water to obtain gold copper@silver sulfide / copper sulfide colloidal material.

2. The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in claim 1, characterized in that, In step 1, specifically: Step 1.1: Disperse hexadecylamine (HDA) in deionized water using ultrasound to obtain an HDA solution with a concentration of 0.5~1.8 mol / L; the ultrasound dispersion temperature is 30~70℃ and the ultrasound time is 10~50 min. Step 1.2: Under stirring conditions, CuCl2 and HAuCl4 are added to the HDA solution in sequence. After mixing evenly, a glucose solution with a concentration of 0.8~1.2 mol / L is added. The mixture is then magnetically stirred at room temperature for 10~40 min at a speed of 400~800 r / min to obtain a mixed solution. Step 1.3: Transfer the mixture to an oil bath and keep it at 80-120℃ for 15-30 min. After washing several times by centrifugation with deionized water at a speed of 6000-10000 r / min for 5-20 min, disperse it in deionized water to obtain the gold-copper nano-alloy precursor.

3. The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in claim 2, characterized in that, In step 2, the heat preservation temperature is 50~100℃ and the heat preservation time is 2~6h.

4. The method for preparing the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in claim 1, characterized in that, In step 3, the pH of the gold-copper@silver solution is adjusted to 12 using a NaOH solution with a concentration of 0.5~2 mol / L.

5. The preparation method of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in claim 1, characterized in that, In step 3, the stirring time is 1-4 hours and the stirring speed is 600-900 r / min.

6. The method for preparing the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in claim 1, characterized in that, In step 4, the stirring time is 10-30 min, the stirring speed is 600-900 r / min, the heat preservation temperature is 80-110℃, and the heat preservation time is 2-3 h.

7. The method for preparing the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in claim 1, characterized in that, In step 5, the centrifugation speed is 6000-10000 r / min and the centrifugation time is 5-20 min.

8. The gold-copper@silver-sulfide / copper-sulfide photocatalytic colloidal material prepared by the method for preparing the core-shell structured gold-copper@silver-sulfide / copper-sulfide photocatalytic colloidal material according to any one of claims 1-7.

9. The application of the core-shell structured gold-copper@silver sulfide / copper sulfide photocatalytic colloidal material as described in any one of claims 1-7 in the photocatalytic hydrogen production of water splitting.

Images