Preparation method of carbon dot-regulated copper and cuprous oxide ratio nanocomposite

Abstract

The application discloses a kind of carbon point regulation copper and cuprous oxide ratio nanocomposite preparation method, which utilizes the cuprous oxide on the electron-deficient group such as carboxyl group adsorbed on the surface of carbon point and is not easy to be reduced to zero by ascorbic acid, effectively protects the cuprous oxide around carbon point, plays the regulation role of copper and cuprous oxide component, while the transient photocurrent response is excellent, and more photo-generated electrons are generated.The nanocomposite preparation method disclosed in the application can produce a wider wavelength absorption range and has stronger light capturing capacity.

Description

Technical Field

[0001] This invention belongs to the field of new materials, specifically relating to a method for preparing nanocomposite materials with carbon dots controlling the ratio of copper and cuprous oxide. Background Technology

[0002] Designing and constructing high-performance nanocomposites is a prerequisite for the development of nanotechnology. By adjusting the components in the material, the morphology, crystal structure, and band structure of the nanocomposites can be controlled. Furthermore, the synergistic effect between components can be utilized to improve the material's performance, fully leveraging the advantages of each component to meet the needs of different applications. However, the precise synthesis of nanocomposites with different proportions of components to improve or overcome the limitations of individual components remains a challenge in current research.

[0003] Carbon dots (CDs), as zero-dimensional carbon nanomaterials with semiconductor properties, have broad application prospects in fields such as bioimaging, ion detection, photothermal therapy, pollutant degradation, and photocatalysis due to their good biocompatibility, non-toxicity, and ease of functionalization. CDs are a special "core-shell" nanostructure, with a variable internal carbon core and a surface shell composed of numerous oxygen / nitrogen functional groups, such as -COOH, -OH, and NH2. This surface structure endows them with multiple functions and applications. By utilizing the different affinities of functional groups, they can be used as probes to sensitively detect various metal ions. Surface adsorption and electron / energy transfer cause changes in the fluorescence of CDs, such as Fe... 2+ / 3+ Cu 2+ Hg 2+ Pb 2+ Furthermore, these functional groups also endow CDs with excellent electron donor or electron acceptor functions under certain conditions. The electron donor capability of CDs can reduce copper salts to zero-valent metal elements under hydrothermal conditions. Similarly, the electron acceptor function of CDs can, under certain conditions, maintain copper salts in a monovalent state, preventing them from being reduced to zero-valent metal elements by reducing agents. This achieves a suitable ratio between the copper and cuprous oxide components, promoting the synergistic effect of the multi-component nanocomposite material. Simultaneously, the mediating effect of carbon dots can enhance photoinduced absorption and accelerate carrier separation and migration, thus improving its catalytic performance. Summary of the Invention

[0004] To adjust the proportions of the components in the nanocomposite material and thus further improve its catalytic performance, the technical solution adopted in this invention is as follows:

[0005] A method for preparing nanocomposites with carbon dots controlling the ratio of copper to cuprous oxide, comprising the following steps:

[0006] Step 1: Add 15-20 mg of carbon dot powder to 20 mL of deionized water and ultrasonically disperse for 0.5-1.5 h at 20-50 °C and 40-70 kHz to obtain a brownish-yellow carbon dot suspension.

[0007] Step 2: Add 37.5–50 mg of 0.15–0.2 mmol copper sulfate pentahydrate or copper nitrate trihydrate to the carbon dot suspension obtained in Step 1, and stir at 500–700 rpm for 0.5–1.5 h at 20–50 °C to obtain a dark brown suspension.

[0008] Step 3: Add 0.3-0.4 mmol of sodium hydroxide to the dark brown suspension obtained in Step 2, and stir at 700-900 rpm for 0.5-1.5 h at 20-50 °C to obtain a dark green suspension; wherein the molar mass ratio of sodium hydroxide to copper sulfate pentahydrate is 2:1.

[0009] Step 4: Add 3.75–5 mmol of ascorbic acid to the dark green suspension obtained in Step 3. Stir at 500–700 rpm for 3–5 hours at 20–50°C. The color of the suspension changes from yellow to brown to dark brown. Then, centrifuge the dark brown suspension to obtain a dark brown precipitate. Wash the precipitate three times in sequence with deionized water and anhydrous ethanol, and centrifuge at 10,000 rpm for 5 minutes. Place the precipitate in a vacuum drying oven and dry it at 60–90°C for 8–12 hours to obtain the carbon dot-regulated copper-based nanocomposite material.

[0010] The carbon dot powder is prepared according to the method for preparing multicolor luminescent tunable carbon dots using coal pitch disclosed in patent ZL201610534465.4, and is obtained by selectively etching coal pitch with formic acid and hydrogen peroxide.

[0011] The present invention has the following beneficial effects:

[0012] Because the carbon dots contain electron-deficient groups such as carboxyl groups on their surface, the cuprous oxide adsorbed on these functional groups is not easily reduced to zero valence by ascorbic acid, effectively protecting the cuprous oxide surrounding the carbon dots. This plays a regulatory role in the copper and cuprous oxide composition. Simultaneously, it exhibits excellent transient photocurrent response, generating more photogenerated electrons. The resulting copper-based nanocatalyst, due to the synergistic effect of copper and cuprous oxide and the mediation of carbon dots, produces a wider wavelength absorption range and stronger light-harvesting ability. It also exhibits excellent water evaporation rates at interfaces, showing great application potential in seawater desalination, water purification, and phase change energy storage. Attached Figure Description

[0013] Figure 1The X-ray diffraction pattern of the copper-based nanocomposite material with carbon dot regulation synthesized in this invention;

[0014] Figure 2 Transmission electron microscope (TEM) image of the carbon dot-regulated copper-based nanocomposite material synthesized in this invention;

[0015] Figure 3 High-resolution transmission electron microscope image of the carbon dot-regulated copper-based nanocomposite material synthesized in this invention;

[0016] Figure 4 The transient photocurrent response diagram of the copper-based nanocomposite material with carbon dot modulation synthesized in this invention is shown.

[0017] Figure 5 The image shows the Mott-Schottky curve of the carbon dot-regulated copper-based nanocomposite material synthesized in this invention.

[0018] Figure 6 This is a graph showing the hydrogen production rate of the carbon dot-regulated copper-based nanocomposite material synthesized in this invention at the MS interface.

[0019] Figure 7 The graph shows the conversion rate of hydrogenation reduction of p-nitrophenol in the carbon dot-regulated copper-based nanocomposite material synthesized in this invention.

[0020] Figure 8 This is the solid absorption spectrum of the copper-based nanocomposite material with carbon dot regulation synthesized in this invention;

[0021] Figure 9 This is a diagram showing the interfacial water evaporation rate of the copper-based nanocomposite material synthesized by carbon dots in this invention. Detailed Implementation

[0022] The detailed technical solution of the present invention is described below with reference to the accompanying drawings:

[0023] A method for preparing nanocomposites with carbon dots controlling the ratio of copper to cuprous oxide, comprising the following steps:

[0024] Step 1: Add 15-20 mg of carbon dot powder to 20 mL of deionized water and ultrasonically disperse for 0.5-1.5 h at 20-50 °C and 40-70 kHz to obtain a brownish-yellow carbon dot suspension.

[0025] Step 2: Add 37.5–50 mg of 0.15–0.2 mmol copper sulfate pentahydrate or copper nitrate trihydrate to the carbon dot suspension obtained in Step 1, and stir at 500–700 rpm for 0.5–1.5 h at 20–50 °C to obtain a dark brown suspension.

[0026] Step 3: Add 0.3-0.4 mmol of sodium hydroxide to the dark brown suspension obtained in Step 2, and stir at 700-900 rpm for 0.5-1.5 h at 20-50 °C to obtain a dark green suspension; wherein the molar mass ratio of sodium hydroxide to copper sulfate pentahydrate is 2:1.

[0027] Step 4: Add 3.75–5 mmol of ascorbic acid to the dark green suspension obtained in Step 3. Stir at 500–700 rpm for 3–5 hours at 20–50°C. The color of the suspension changes from yellow to brown to dark brown. Then, centrifuge the dark brown suspension to obtain a dark brown precipitate. Wash the precipitate three times in sequence with deionized water and anhydrous ethanol, and centrifuge at 10,000 rpm for 5 minutes. Place the precipitate in a vacuum drying oven and dry it at 60–90°C for 8–12 hours to obtain the carbon dot-regulated copper-based nanocomposite material.

[0028] The carbon dot powder is prepared according to the method for preparing multicolor luminescent tunable carbon dots using coal pitch disclosed in patent ZL201610534465.4, and is obtained by selectively etching coal pitch with formic acid and hydrogen peroxide.

[0029] Example 1

[0030] A method for preparing nanocomposites with carbon dots controlling the ratio of copper to cuprous oxide, comprising the following steps:

[0031] Step 1: Add 15 mg of carbon dot powder to 20 mL of deionized water and ultrasonically disperse for 1 h at 40 °C and 70 kHz to obtain a brownish-yellow carbon dot suspension.

[0032] Step 2: Add 40 mg of 0.18 mmol copper sulfate pentahydrate or copper nitrate trihydrate to the carbon dot suspension obtained in Step 1, and stir at 600 rpm for 1.5 h at 40 °C to obtain a dark brown suspension.

[0033] Step 3: Add 0.4 mmol of sodium hydroxide to the dark brown suspension obtained in Step 2, and stir at 800 rpm for 1.5 h at 50 °C to obtain a dark green suspension; wherein the molar mass ratio of sodium hydroxide to copper sulfate pentahydrate is 2:1.

[0034] Step 4: Add 5 mmol of ascorbic acid to the dark green suspension obtained in Step 3. Stir at 600 rpm for 4 hours at 50°C. The color of the suspension changes from yellow to brown to dark brown. Then, centrifuge the dark brown suspension to obtain a dark brown precipitate. Wash the precipitate three times in sequence with deionized water and anhydrous ethanol, and centrifuge at 10000 rpm for 5 minutes. Place the precipitate in a vacuum drying oven and dry it at 80°C for 10 hours to finally obtain the carbon dot-regulated copper-based nanocomposite material.

[0035] The obtained carbon dot-modulated copper-based nanocomposites were tested. Figure 1 The figure shows the X-ray diffraction pattern of the copper-based nanocomposite material synthesized by the present invention with carbon dots. As can be seen from the figure, the introduction of carbon dots adjusts the ratio of copper to cuprous oxide content. Figure 2 Transmission electron microscopy (TEM) images of copper-based nanocomposites regulated by carbon dots clearly show the nanoscale structure, exhibiting a spherical shape. Figure 3 The high-resolution transmission electron microscope (TEM) image of the carbon dot-controlled copper-based nanocomposite material shows that cuprous oxide exists on the surface of carbon dots, indicating that the addition of carbon dots protects cuprous oxide from reduction, thereby controlling the ratio of copper to cuprous oxide. Figure 4 The image shows the transient photocurrent response of the carbon dot-controlled copper-based nanocomposite material. The image indicates that under the same conditions, the addition of carbon dots increases the photocurrent response density of the material, suggesting that the heterogeneous interface of carbon dots, copper, and copper oxides recombines, and has a good ability to control photogenerated electron-hole pairs. Figure 5 The image shows the Mott-Schottky curve of the copper-based nanocomposite material regulated by carbon dots. The carrier density Nd can be calculated from the image to be 3.36 × 10⁻⁶. 21 This indicates that the material exhibits a localized surface plasmon resonance effect. Figure 6 The figure shows the hydrogen production rate of the carbon-dot-regulated copper-based nanocomposite on the MS interface. The figure shows that the material has excellent photocatalytic hydrogen production rate of ammonia borane. The hydrogen production can reach 632 mL when the ammonia borane concentration is 20 mM, which is 4.6 times higher than that of the copper-based nanocomposite without carbon dots. Figure 7 The graph shows the conversion rate of the hydrogenation reduction of p-nitrophenol by the copper-based nanocomposite material with carbon dot regulation. The graph shows that the excellent photogenerated electron ability enables the material to have a good effect in catalyzing the hydrogenation reduction of p-nitrophenol, achieving a conversion rate of 96.7% in 20 min, while the copper-based nanocomposite material without carbon dot intervention only has a conversion rate of 30.6% in 80 min. Figure 8 The solid-state absorption spectrum of the copper-based nanocomposite material synthesized by the present invention with carbon dots shows that the addition of carbon dots makes the material absorb light significantly higher than that of copper-based materials without carbon dots and the light absorption range is wider. Figure 9The diagram shows the interfacial water evaporation rate of the carbon dot-regulated copper-based nanocomposite material. It illustrates the excellent water evaporation rate (2.4 kg·m³) at the MS interface. -2 ·h -1 Evaporation rate.

Claims

1. A method for preparing nanocomposite materials with a copper-to-cuprous oxide ratio controlled by carbon dots, characterized in that: The following steps are adopted: Step 1: Add 15–20 mg of carbon dot powder to 20 mL of deionized water and ultrasonically disperse for 0.5–1.5 h at 20–50 °C and 40–70 kHz to obtain a brownish-yellow carbon dot suspension. Step 2: Add 0.18 mmol of copper sulfate pentahydrate or copper nitrate trihydrate to the carbon dot suspension obtained in Step 1, and stir at 500-700 rpm for 0.5-1.5 h at 20-50 °C to obtain a dark brown suspension. Step 3: Add 0.4 mmol of sodium hydroxide to the dark brown suspension obtained in Step 2, and stir at 700–900 rpm for 0.5–1.5 h at 20–50 °C to obtain a dark green suspension; Step 4: Add 3.75–5 mmol of ascorbic acid to the dark green suspension obtained in Step 3. Stir at 500–700 rpm for 3–5 h at 20–50°C. The color of the suspension changes from yellow to brown to dark brown. Then, centrifuge the dark brown suspension to obtain a dark brown precipitate. Wash the precipitate three times in sequence with deionized water and anhydrous ethanol, and centrifuge at 10,000 rpm for 5 min. Place the precipitate in a vacuum drying oven and dry it at 60–90°C for 8–12 h to finally obtain the carbon dot-regulated copper-based nanocomposite material.

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