A cross-linked aminated carbon dot-based wet electro-generator device, and a preparation method and application thereof

Abstract

The application discloses a preparation method and application of a wet electric generator based on heat crosslinking amino carbon dots, which comprises the following steps: depositing amino carbon dots on a flexible non-woven fabric substrate, and adopting a heat-induced crosslinking strategy to make the carbon dot surface amino and the oxygen-containing functional groups of the substrate undergo dehydration condensation reaction to form a stable chemical bond network. The structure significantly enhances the interfacial bonding force between the carbon dots and the substrate, inhibits the migration and shedding of the carbon dots in a humid environment, and optimizes the moisture absorption and ion transmission efficiency. Experimental results show that the output voltage of the device after heat treatment can reach 0.90V under 85% relative humidity, and the short-circuit current can reach 44 mu A, which is much higher than that of the untreated sample (0.56V, 10 mu A). The device also shows excellent flexibility, washing resistance and stable output for up to 120 hours. Through modular series / parallel integration, a distributed power supply system can be constructed to drive low-power electronic devices such as LEDs and calculators.

Description

Technical Field

[0001] This invention belongs to the field of new energy and nanomaterials technology, specifically relating to a wet power generation device, and more particularly to an aminated carbon dot-based wet power generation device with enhanced interfacial stability through thermal crosslinking, its preparation method, and its application. Background Technology

[0002] With the rapid development of the Internet of Things and wearable electronic devices, the demand for distributed, sustainable, and self-powered micro-energy systems is becoming increasingly urgent. Wet power generation technology can directly utilize the ubiquitous moisture gradient in the environment to generate electricity. It has outstanding advantages such as wide availability of raw materials, environmental friendliness, and miniaturization, making it one of the ideal choices for building next-generation self-powered systems.

[0003] Carbon dots, as an emerging nanomaterial, possess advantages such as simple synthesis, rich and tunable surface functional groups, and strong hygroscopicity, and have been introduced into the field of wet power generation in recent years, showing great potential. Currently, research on carbon dot-based wet power generation devices mainly focuses on utilizing the oxygen-containing functional groups (such as carboxyl and hydroxyl groups) on the carbon dot surface to ionize and generate electrical signals. However, compared to oxygen-containing groups, amino groups (-NH2) have stronger proton affinity and water molecule dissociation ability, theoretically enabling higher surface charge density and ion transport efficiency, making them an ideal choice for further improving wet power output performance. Nevertheless, research on the application of amination-modified carbon dots (A-CDs) in wet power generation is still in its infancy, and their enormous potential remains to be explored.

[0004] On the other hand, existing carbon dot-based wet electrostatic precipitators typically load carbon dots onto porous substrates (such as paper or cloth) through physical adsorption. This weak interaction leads to the carbon dot active layer easily dissociating, migrating, or agglomerating in continuously operating humid environments, causing a rapid decay in the device's electrical output and severely limiting its practical lifespan. This problem becomes even more pronounced when using amination-modified carbon dots, which have even weaker interfacial forces, as highly active amination-modified carbon dots are more easily detached from the substrate surface by water molecule penetration. Therefore, the key to overcoming the performance bottleneck of carbon dot-based wet electrostatic precipitators lies in how to utilize the high activity of amination-modified carbon dots while firmly and stably fixing them onto the substrate to construct a power generation interface that is both efficient and robust. Summary of the Invention

[0005] Purpose of the invention: To address the technical problems of weak interfacial bonding, poor stability, and easy degradation of output performance in existing carbon dot-based wet electrostatic precipitators, this invention aims to provide a wet electrostatic precipitator with high output performance, excellent long-term stability, and strong interfacial bonding, as well as a simple and efficient preparation method thereof.

[0006] Technical solution: To achieve the above objectives, the present invention adopts the following technical solution: A method for fabricating a wet-electric power generation device based on thermally cross-linked aminated carbon dots includes the following steps: S1, using compounds containing carboxyl or hydroxyl groups and compounds containing amino groups as raw materials, synthesizes ammoniated carbon dots A-CDs via a hydrothermal method; S2, the A-CDs solution obtained in step S1 is loaded onto a porous flexible substrate to form an A-CDs@substrate composite material; S3. Under a protective atmosphere, the composite material obtained in step S2 is heat-treated to covalently crosslink A-CDs with the substrate, resulting in a thermally crosslinked aminated carbon dot TA-CDs@substrate composite material. S4. Asymmetric electrodes are set on both sides of the TA-CDs@substrate composite material obtained in step S3, and the composite material is assembled into a wet electro-electric power generation device.

[0007] Furthermore, step S1 requires an excess of amino groups, and the heat treatment in step S3 is performed at a temperature of 200-300°C for 1-4 hours; the protective atmosphere is nitrogen or argon.

[0008] Furthermore, the porous flexible substrate is a nonwoven fabric, filter paper, or cotton fabric.

[0009] Furthermore, in step S4, one of the asymmetric electrodes is a liquid metal alloy electrode, and the other is a conductive sponge electrode.

[0010] Furthermore, the liquid metal alloy is a tin-bismuth alloy.

[0011] Furthermore, in step S2, the A-CDs solution is loaded by immersion or drop coating.

[0012] Furthermore, the carboxyl or hydroxyl-containing compound is selected from citric acid and glucose; the amino-containing compound is selected from triethylenetetramine and ethylenediamine.

[0013] The present invention also claims protection for the application of any of the above-described wet power generation devices in the fields of wearable electronic devices, distributed micro energy systems, or environmental energy harvesting.

[0014] Furthermore, in the above applications, multiple wet power generation devices are integrated in series and / or parallel to power low-power electronic devices or to build flexible self-powered systems.

[0015] The wet-electric power generation device of this invention exhibits an open-circuit voltage of not less than 0.8V and a short-circuit current of not less than 40μA in an environment with a relative humidity of 85%. After continuous operation for 120 hours in an environment with a relative humidity of 60%, its voltage output attenuation rate is less than 20%.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following advantages: The interface exhibits strong bonding and excellent stability: heat treatment induces dehydration condensation between the amino groups on the surface of the amination carbon dots and the oxygen-containing functional groups (such as hydroxyl groups) of the substrate (such as cellulose), forming a covalent cross-linked network. This strong chemical bond firmly anchors the carbon dots to the substrate, fundamentally solving the problem of active materials easily detaching and migrating under the penetration of water molecules caused by traditional physical adsorption, enabling the device to maintain stable electrical output during long-term (such as 120 hours) continuous operation.

[0017] Significantly improved output performance: The heat treatment process not only forms stable cross-links but also removes low-molecular-weight impurities, optimizes the surface chemical state of carbon dots, and enhances interfacial reactivity. Aminated carbon dots themselves have excellent hygroscopic and ionization capabilities. Combined with a preferred asymmetric liquid metal electrode (such as Sn-Bi alloy), their surface can undergo efficient and continuous oxidation reactions in a humid environment and release OH⁻ ions, synergistically promoting charge generation and transport. This significantly improves the open-circuit voltage of a single device (up to 0.9V or higher), which is superior to most reported carbon dot-based wet-electric power generation devices.

[0018] High flexibility and easy integration: Based on flexible fabric, the device possesses excellent flexibility and bending resistance. The modular structural design facilitates large-scale series and parallel integration through simple sewing, weaving, or circuit connections, flexibly constructing power supply systems that meet different voltage and current requirements, and can directly drive commercial electronic devices such as LEDs and calculators.

[0019] The preparation process is simple and environmentally friendly: the entire preparation process is based on hydrothermal and heat treatment, the raw materials are cheap and readily available, no complex equipment or harsh conditions are required, it is suitable for large-scale production, and has broad prospects for industrial application. Attached Figure Description

[0020] Figure 1 This is a morphological characterization of A-CDs (TEM images, including HRTEM insets and particle size distribution histograms). Figure 2 These are the FTIR spectra of the chemical structure characterization of A-CDs.

[0021] Figure 3 These are ATR-FTIR contrastive spectra characterizing the interfacial chemical changes of A-CDs@Fabric and TA-CDs@Fabric before and after heat treatment, showing C=C enhancement and CN formation.

[0022] Figure 4 This is a comparison of the XPS full spectrum of elemental composition changes before and after heat treatment (A-CDs@Fabric and TA-CDs@Fabric).

[0023] Figure 5The chemical state changes of nitrogen before and after heat treatment (comparison of N1s high-resolution XPS spectra) between A-CDs@Fabric and TA-CDs@Fabric.

[0024] Figure 6 This is a comparison of the chemical state of carbon before and after heat treatment (A-CDs@Fabric and TA-CDs@Fabric), showing the increase of CN bonds.

[0025] Figure 7 It is a comparison of core output performance (voltage / current output bar charts or curves of TA-CDs@Fabric and A-CDs@Fabric at 85%RH).

[0026] Figure 8 It is the humidity response performance (output voltage and current curves of TA-CDs@Fabric under different relative humidities).

[0027] Figure 9 This is an interface stability (water wash resistance) verification (left: comparison of sample photos before and after water washing; right: comparison of device performance bar charts before and after water washing).

[0028] Figure 10 This is a mechanical flexibility test of the wet power generation device described in this invention (output voltage stability curves of the device at different bending angles).

[0029] Figure 11 This is a long-term operational stability test of the wet power generation device described in this invention (voltage-time curve of the device operating continuously for 120 hours at 60%RH).

[0030] Figure 12 It is an optimization of electrode materials (output voltage / current histogram of the device when using different electrode materials).

[0031] Figure 13 This is a diagram demonstrating device integration.

[0032] Figure 14 This is a schematic diagram of a parallel integrated configuration.

[0033] Figure 15 This is a schematic diagram of a series integrated configuration.

[0034] Figure 16 It is the integrated output performance (a photo or graph of the output voltage after different numbers of devices are connected in series). Detailed Implementation

[0035] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0036] Example 1: Fabrication and Performance Testing of Wet Electric Power Generation Device Based on Thermally Crosslinked Aminated Carbon Dots Synthesis of amination carbon dots (A-CDs): Weigh 1.0 g of citric acid (a carboxyl-containing compound) and 10.0 mL of triethylenetetramine (TETA, 70% purity) (an amino-containing compound), and sonicate to mix thoroughly. Transfer the mixture to a 50 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE) and react at 220 °C for 2 hours. After the reaction, allow it to cool naturally to room temperature to obtain a crude solution with dark brown carbon dots. Centrifuge the solution at 8000 rpm for 10 minutes and collect the supernatant. Dialyze the solution in deionized water for 6 hours using a dialysis bag with a molecular weight cutoff of 1000 Da to remove small molecule impurities. The resulting purified A-CDs aqueous solution is stored at 4 °C for later use.

[0037] Preparation of A-CDs@Fabric composite materials: Take a clean, dry piece of nonwoven fabric (2cm × 2cm) and completely immerse it in the prepared A-CDs aqueous solution for 30 minutes to ensure that the carbon dots are fully loaded into the porous structure of the fabric. After removal, dry it in a 60℃ oven to obtain the A-CDs@Fabric composite material.

[0038] Preparation of TA-CDs@Fabric composites by thermal crosslinking: The obtained dried A-CDs@Fabric sample was placed in a tube furnace. High-purity nitrogen was introduced as a protective atmosphere, and the temperature was increased to 250°C at a rate of 5°C / min, and maintained at this temperature for 2 hours for heat treatment. After heat treatment, the sample was naturally cooled to room temperature in a nitrogen atmosphere to obtain a thermally crosslinked aminated carbon dot composite material, denoted as TA-CDs@Fabric. This process promotes the dehydration condensation reaction between the amino groups (-NH2) on the surface of A-CDs and the hydroxyl groups (-OH) on the surface of fabric fibers (such as cellulose), forming stable covalent crosslinks.

[0039] Assembly of wet electrostatic precipitators (MEG): On the upper surface (functional layer side) of the obtained TA-CDs@Fabric composite material, a layer of conductive fabric impregnated with a tin-bismuth liquid metal alloy (Sn42 / Bi58) is laid as the anode. On its lower surface, a nickel-copper composite conductive sponge is tightly attached as the cathode. The electrodes are led out using conductive silver paste and flexible wires, thus assembling an independent wet power generation unit.

[0040] Example 2: Characterization and Performance Testing of Materials and Devices Morphology and structural characterization of carbon dots: The A-CDs aqueous solution prepared in Example 1 was dropped onto a copper grid, allowed to dry naturally, and then subjected to transmission electron microscopy (TEM) testing. Figure 1 As shown, A-CDs are well dispersed, quasi-spherical, and have an average particle size of approximately 3.2 nm. High-resolution TEM (HRTEM) images show clear lattice fringes with an interplanar spacing of approximately 0.21 nm, corresponding to the (100) crystal plane of graphitic carbon. Fourier transform infrared spectroscopy (FTIR) measurements (such as...) Figure 2 As shown in the figure, a broad peak exists in the 3600-3000 cm⁻¹ range, attributed to the stretching vibrations of OH and NH; the peaks at 1643 cm⁻¹ and 1565 cm⁻¹ correspond to the vibrations of C=C and C=O / C=N, respectively; and the peak at 1317 cm⁻¹ is the CN vibration. These results indicate the successful synthesis of amino-rich carbon dots.

[0041] Characterization of interfacial chemical structure changes before and after heat treatment (key evidence): To demonstrate the occurrence of thermal crosslinking, ATR-FTIR and XPS analyses were performed on the samples from Example 1 before heat treatment (A-CDs@Fabric) and after heat treatment (TA-CDs@Fabric).

[0042] ATR-FTIR analysis: such as Figure 3 As shown, compared with A-CDs@Fabric, TA-CDs@Fabric exhibits a significantly enhanced absorption peak at 1643 cm⁻¹ (C=C), indicating an increased degree of carbonization. Simultaneously, the absorption in the 3600-3000 cm⁻¹ region (-OH and -NH₂) weakens, while the vibration near 1314 cm⁻¹ (CN) strengthens. This is attributed to the formation of CN bonds through dehydration of amino and hydroxyl groups, providing direct spectroscopic evidence of covalent cross-linking.

[0043] XPS Analysis: XPS Full Spectrum as shown Figure 4 As shown, the O / C atomic ratio and N content decrease after heat treatment. High-resolution N1s spectra (e.g.) Figure 5As shown in the figure, heat treatment resulted in a decrease in the relative content of amino nitrogen (~399.6 eV), while the relative contents of pyrrole nitrogen (~398.8 eV) and graphitic nitrogen (~401.3 eV) increased. High-resolution C1s spectra (as shown in the figure) indicate that heat treatment decreased the relative content of amino nitrogen (~399.6 eV), while increasing the relative content of pyrrole nitrogen (~398.8 eV) and graphitic nitrogen (~401.3 eV). Figure 6 As shown in the figure, the proportion of the component representing CN / CO bonds (~285.4 eV) increases significantly in TA-CDs@Fabric. These changes collectively confirm that the heat treatment process promotes carbonization of carbon dots and the formation of CN covalent bonds with the substrate.

[0044] Device output performance and stability testing (core performance): The TA-CDs@FabricMEG device assembled in Example 1 was placed in a constant temperature and humidity chamber, and its electrical output performance was tested using an electrochemical workstation.

[0045] Basic output performance: At 85% relative humidity (RH), the device's open-circuit voltage reaches 0.90V, and its short-circuit current reaches 44μA (see [reference]). Figure 7 The results showed that the device was significantly better than the control device without heat treatment (A-CDs@FabricMEG, which output only 0.56V and 10μA under the same conditions).

[0046] Humidity response performance: Device output is positively correlated with humidity. Over a wide humidity range of 25% to 85%, the output voltage linearly increases from 0.42V to 0.90V, and the current increases from 135nA to 44μA (see [reference]). Figure 8 This demonstrates its potential for working around the clock.

[0047] Interface stability (wash resistance) verification: Comparative experiments were conducted to verify the enhancing effect of thermal crosslinking on interfacial bonding. For example... Figure 9 As shown, A-CDs@Fabric and TA-CDs@Fabric samples were immersed in deionized water, stirred, and then dried. A-CDs@Fabric showed a significant color change, and the washing solution emitted strong fluorescence under UV light, indicating the detachment of numerous carbon dots; the assembled device exhibited severe performance degradation (voltage dropped from 0.56V to 0.18V). Conversely, the TA-CDs@Fabric sample maintained stable appearance and performance, and the washing solution showed almost no fluorescence, demonstrating that covalent cross-linking effectively prevented the loss of carbon dots in a humid environment.

[0048] Mechanical flexibility test: When the device is bent to a 150° angle, its output voltage shows no significant attenuation (see [reference]). Figure 10 This indicates that the device has excellent flexibility and mechanical stability, making it suitable for wearable applications.

[0049] Long-term operational stability test: The device was continuously tested for 120 hours (5 days) under conditions of 60%RH and 25°C, and its open-circuit voltage stabilized at approximately 0.7V (see [link to relevant documentation]). Figure 11 No significant performance degradation was observed, demonstrating the excellent long-term operating life of the device of this invention.

[0050] Electrode material optimization: The effects of different electrode materials on the performance of TA-CDs@FabricMEG were tested. As shown in Figure 12, the CS / LM combination, using a tin-bismuth liquid metal (LM) anode and a nickel-copper conductive sponge (CS) cathode, exhibited the best performance and the highest output voltage (~0.9V). This is attributed to the sustained electrochemical oxidation activity of the liquid metal in a humid environment (e.g., Sn to SnO). x ²⁻ and release OH⁻) and its excellent interfacial contact with the fabric substrate. The output of other electrode combinations (such as CS / SS, CS / Cu, CS / Al) is significantly lower than that of the CS / LM combination.

[0051] Example 3

[0052] To demonstrate the scalability and practicality of this invention, device integration experiments were conducted (see [link]). Figure 13 ).

[0053] Integration diagram: Multiple independent TA-CDs@FabricMEG units can be flexibly integrated in series or parallel via sewing or circuit connection (see...). Figure 14 , 15 ).

[0054] Series output: Connecting 3 device units in series increases the output voltage to approximately 2.5V; connecting 15 device units in series can increase the output voltage to over 10V (see [link]). Figure 16 This verifies the linear scalability of output with respect to the number of units.

[0055] Application Demonstration: Using a series-integrated array of devices, multiple light-emitting diodes (LEDs) were successfully lit, driving a commercial calculator to operate continuously. This demonstrates that the wet-electric power generation device of this invention can serve as a practical micro-energy source to power low-power electronic devices.

[0056] Example 4: Optimization of preparation conditions In the synthesis of A-CDs, the dosage of the key raw material triethylenetetramine (TETA) was optimized. The carboxyl-containing compound citric acid was kept constant at 1.0 g, while the volume of TETA was varied (1-15 mL). Experiments showed that as the TETA dosage increased to 10 mL, the output voltage and current of A-CDs@FabricMEG continuously improved. However, when the TETA dosage exceeded 10 mL, the output performance began to decline, presumably due to excessive cross-linking of carbon dots caused by the excess amine, clogging the fabric pores. Therefore, the optimal TETA dosage was determined to be 10 mL (corresponding to a 70% purity product). This optimization process demonstrates the controllability of the process in this invention.

[0057] Comparative Example 1 (Untreated device): The preparation process was exactly the same as in Example 1, but the thermal crosslinking treatment in step S3 was omitted, and the A-CDs@Fabric obtained in S2 was used directly for device assembly. The performance data of this comparative device has been shown in the aforementioned performance comparisons (e.g., output of only 0.56V, poor water washability, and insufficient long-term stability), which fully demonstrates that the thermal crosslinking treatment step is an indispensable key step for improving the output performance and stability of the device.

[0058] The above embodiments detail the fabrication method, characterization techniques, and performance advantages of the wet power generation device of the present invention. By introducing a thermally induced covalent crosslinking strategy, the present invention successfully solves the core problem of weak bonding between carbon dots and the substrate interface, obtaining a high-output, highly stable, and highly flexible wet power generation device, and demonstrating its great potential for modular integration and practical applications.

Claims

1. A method for fabricating a wet-electric power generation device based on thermally cross-linked amination carbon dots, characterized in that... Includes the following steps: S1, using compounds containing carboxyl or hydroxyl groups and compounds containing amino groups as raw materials, synthesizes ammoniated carbon dots A-CDs via a hydrothermal method; S2, the A-CDs solution obtained in step S1 is loaded onto a porous flexible substrate to form an A-CDs@substrate composite material; S3. Under a protective atmosphere, the composite material obtained in step S2 is heat-treated to covalently crosslink A-CDs with the substrate, resulting in a thermally crosslinked aminated carbon dot TA-CDs@substrate composite material. S4. Asymmetric electrodes are set on both sides of the TA-CDs@substrate composite material obtained in step S3, and the composite material is assembled into a wet electro-electric power generation device.

2. The preparation method according to claim 1, characterized in that: Step S1 requires an excess of amino groups, and the heat treatment in step S3 is performed at a temperature of 200-300°C for 1-4 hours; the protective atmosphere is nitrogen or argon.

3. The preparation method according to claim 1, characterized in that: The porous flexible substrate is a nonwoven fabric, filter paper, or cotton fabric.

4. The preparation method according to claim 1, characterized in that: The asymmetric electrode mentioned in step S4 has one electrode as a liquid metal alloy electrode and the other electrode as a conductive sponge electrode.

5. The preparation method according to claim 4, characterized in that: The liquid metal alloy is a tin-bismuth alloy.

6. The preparation method according to claim 1, characterized in that: In step S2, the A-CDs solution is loaded by immersion or drop coating.

7. The preparation method according to claim 1, characterized in that: The compounds containing carboxyl or hydroxyl groups are selected from citric acid and glucose; the compounds containing amino groups are selected from triethylenetetramine and ethylenediamine.

8. The application of the wet power generation device according to any one of claims 1-7 in the fields of wearable electronic devices, distributed micro energy systems, or environmental energy harvesting.

9. The application according to claim 8, characterized in that: Multiple wet power generation devices can be integrated in series and / or parallel to power low-power electronic devices or to build flexible self-powered systems.

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