A triboelectric nanogenerator for fluid energy harvesting, its preparation method, and its application in heavy metal ion removal

Abstract

The present invention discloses a friction nanogenerator for fluid energy collection, a preparation method thereof, and an application in the removal of heavy metal ions, and belongs to the field of nanogenerator technology. The friction nanogenerator for fluid energy collection of the present invention comprises: a base, a plurality of support plates, a stressed turbine blade, a rotating shaft, a contact-separation component, and a sliding friction component. Through structural innovation and optimization, the present invention utilizes the contact-separation mode to achieve high voltage, while taking into account the independent layer mode to achieve high current output. This composite structural design improves the adaptability of the system, enabling it to maintain efficient energy conversion in a variety of working environments, overcoming the limitations of the unbalanced voltage and current output in traditional designs. This composite design not only breaks through the power bottleneck of traditional TENG, but also provides a new idea for efficient energy capture in complex mechanical environments. Compared with the existing technology, the present invention has a significant improvement in electrical output performance and device operation.

Description

Technical Field

[0001] The present invention relates to the technical field of nanogenerators, and in particular to a friction nanogenerator for collecting fluid energy, a preparation method thereof, and an application thereof in removing heavy metal ions. Background Art

[0002] As an emerging energy harvesting technology, the triboelectric nanogenerator (TENG) has attracted widespread attention due to its high efficiency and environmental adaptability in low-frequency mechanical energy conversion. Traditional TENG structural designs are often based on a single operating mode, such as contact-separation or sliding friction. However, while these traditional single modes can achieve effective energy conversion to a certain extent, they often struggle to achieve both high voltage output and continuous current stability. Furthermore, limitations in material selection and structural design have hindered their potential for breakthrough performance.

[0003] With the development of social economy, the pollution problem of heavy metal ions is becoming increasingly serious. Heavy metal ions mainly come from various industries such as printing, chemical industry, and electroplating. Heavy metal ions such as lead ions, cadmium ions, and copper ions are present in water resources and soil due to their strong toxicity and difficulty in degradation, which has a great impact on the ecological environment and human health. Traditional methods for removing heavy metal ions include chemical precipitation, membrane separation, and adsorption. Although these methods can effectively remove heavy metal ions, they often have problems such as high energy consumption, high cost, secondary pollution, and complex operation.

[0004] Therefore, how to develop a friction nanogenerator and its preparation method and application in heavy metal ion removal that can overcome the limitations of unbalanced voltage and current output in traditional designs, improve electrical output performance and fluid energy collection during device operation are technical problems that technicians in this field urgently need to solve. Summary of the Invention

[0005] In view of this, the present invention provides a triboelectric nanogenerator for fluid energy harvesting, a preparation method thereof, and an application in heavy metal ion removal.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A triboelectric nanogenerator for fluid energy collection, comprising: a base, a plurality of support plates, a stressed turbine blade, a rotating shaft, a contact and separation component, and a sliding friction component;

[0008] The support plates are fixedly mounted on both sides of the base, and bearings are respectively embedded at the top ends of the support plates. The rotating shaft is rotatably connected to the support plates through the bearings. The forced turbine blades include a mounting portion and a plurality of blades, and the plurality of blades are fixedly connected to the outer periphery of the mounting portion. The forced turbine blades are fixedly mounted on one end of the rotating shaft through the mounting portion, and the contact and separation assembly and the sliding friction assembly are respectively mounted on the rotating shaft.

[0009] The contact and separation assembly includes a rotor 1 inlaid with a plurality of universal balls, a balloon membrane, a fixed disc provided with a plurality of inlay holes, a plurality of copper electrodes coated with Ecoflex / ZnS films, a plurality of copper electrodes covered with sponge films, a gasket, a stator 1, a bracket 1, and a bracket 2. The gasket and the copper electrodes covered with sponge films are respectively fixedly connected to the stator 1, the thickness of the gasket is greater than the thickness of the copper electrodes covered with sponge films, the copper electrodes coated with Ecoflex / ZnS films are inlaid in the inlay holes of the fixed disc, the Ecoflex / ZnS films are close to the sponge films, the balloon membrane covers the surface of the fixed disc, and the universal balls are in close contact with the balloon membrane.

[0010] The centers of the rotor 1, the balloon membrane, the fixed disc, and the stator 1 are provided with through holes. The rotating shaft passes through the through hole in the center of the rotor 1 and is fixedly connected to the rotor 1. The rotating shaft passes through the through holes in the center of the balloon membrane, the fixed disc, and the stator 1 in sequence. The apertures of the through holes of the balloon membrane, the fixed disc, and the stator 1 are larger than the diameter of the rotating shaft. The stator 1 is fixedly mounted on the bracket 1, the fixed disc is fixedly mounted on the bracket 2, and the brackets 1 and 2 are respectively fixedly mounted on the base.

[0011] The sliding friction assembly includes a second rotor, a second stator, and a third bracket. The main bodies of the second rotor and the second stator are PCBs. Grid-shaped copper electrodes are evenly arranged on the second rotor and the second stator. A PTFE layer is attached to the copper electrode of the second rotor, and a GF film is attached to the copper electrode of the second stator. The PTFE layer and the GF film are in close contact.

[0012] A through hole is provided at the center of the rotor 2 and the center of the stator 2. The rotating shaft passes through the through hole of the rotor 2 and is fixedly connected to the rotor 2. The rotating shaft passes through the through hole of the stator 2. The aperture of the through hole of the stator 2 is larger than the diameter of the rotating shaft. The stator 2 is fixedly mounted on the bracket 3, and the bracket 3 is fixedly mounted on the base.

[0013] Furthermore, the shape of rotor one is a circle with a diameter of 200 mm, a through hole of 6 mm in the center, and the material is acrylic with a thickness of 12 mm; the diameter of the universal ball is 18 mm, the material is bearing steel, and the height of the universal ball protruding from rotor one is 5 mm; the shape of the balloon membrane is a circle with a diameter of 200 mm, a through hole of 8 mm in the center, the material is latex, and the thickness is 0.04 mm; the shape of the fixed disk is a circle with a diameter of 200 mm, a through hole of 8 mm in the center, the material is acrylic, and the thickness is 4 mm, and the shape of the inlay holes is a plurality of squares with a side length of 5 cm; the shape of the copper electrode coated with Ecoflex / ZnS film is a plurality of squares with a side length of 5 cm, wherein the thickness of the copper electrode layer is 0.065 mm, and the thickness of the Ecoflex / ZnS film is 0.1 mm; the shape of the copper electrode covered with sponge film is a plurality of squares with a side length of 5 cm, wherein the thickness of the copper electrode layer is 0.065 mm, and the thickness of the sponge film is 0.5 mm; the gasket is in the shape of a long strip, made of acrylic, and 5 mm thick; the shape of stator one is a circle with a diameter of 200 mm, with an 8 mm through hole in the center, made of acrylic, and 5 mm thick; when the universal ball does not rotate into the inlay hole, the distance between the sponge film and the Ecoflex / ZnS film is 5 mm, and the positions of the multiple copper electrodes coated with Ecoflex / ZnS film and the multiple copper electrodes covered with sponge film correspond one to one. When the universal ball rotates into the inlay hole, the positions of the multiple universal balls and the multiple inlay holes correspond one to one.

[0014] Furthermore, the shape of rotor 2 is a circle with a diameter of 200 mm and a through hole of 6 mm in the center. The copper electrode on rotor 2 is set as a ring with an outer diameter of 200 mm and an inner diameter of 70 mm with the center of rotor 2 as the center. The number of grids is 30 and evenly distributed. The shape of stator 2 is a square with a side length of 200 mm and a through hole of 8 mm in the center. The copper electrode on the stator is set as a ring with an outer diameter of 200 mm and an inner diameter of 70 mm with the center of stator 2 as the center. The number of grids is 30 pairs and evenly distributed. One grid on each side of the copper electrode on the stator is selected to extend as a terminal.

[0015] Furthermore, the thickness of the PTFE layer is 0.01 mm, the PTFE layer has the same shape as the rotor 2, and completely covers the rotor 2 when pasted; the thickness of the GF membrane is 0.15 mm, the GF membrane has the same shape as the stator 2, and completely covers the stator 2 when pasted.

[0016] Furthermore, the base, support plate, bracket one, bracket two and bracket three are all made of wood. The base is 35 cm long and 20 cm wide. The support plate is trapezoidal, with a lower base length of 14 cm, an upper base length of 5 cm and a height of 14 cm. Stator one is embedded in bracket one, and the fixed disc is embedded in bracket two. Bracket one and bracket two are 140 mm high and 200 mm wide. Stator two is embedded in bracket three. Bracket three is 140 mm high and 220 mm wide. The length of the rotating shaft is 305 mm, the diameter is 5 mm, and the material is carbon steel.

[0017] The present invention also provides a method for preparing a triboelectric nanogenerator for fluid energy harvesting, comprising the following steps:

[0018] (1) Preparation of copper electrodes coated with Ecoflex / ZnS film: ZnS powder was added to Ecoflex silica gel and stirred to obtain a uniform mixture. The mixture was evenly coated on the surface of a wooden board on which a copper electrode was pre-laid. The coated sample was transferred to a vacuum drying oven for curing to obtain a copper electrode coated with Ecoflex / ZnS film.

[0019] (2) The friction nanogenerator for fluid energy collection is installed according to the structure to obtain this product.

[0020] Furthermore, in step (1), the ZnS powder accounts for 0-13 wt% of the total mass of the ZnS powder and Ecoflex silica gel, the coating thickness is 0.1 mm, the curing temperature is 60°C, and the curing time is 4 h.

[0021] Preferably, in step (1), the ZnS powder accounts for 9 wt % of the total mass of the ZnS powder and Ecoflex silica gel.

[0022] Furthermore, in step (1), the obtained mixture is evenly coated on the surface of the wooden board on which the copper electrode has been pre-laid by spin coating at a rotation speed of 1000 r / min.

[0023] The present invention also provides an application of the fluid energy harvesting friction nanogenerator in removing heavy metal ions.

[0024] Furthermore, a triboelectric nanogenerator with fluid energy harvesting was used to construct an electrodeposition system to remove Cu 2+ , Pb 2+ and Cd 2 + .

[0025] Beneficial Effects of the Invention: This invention proposes a hybrid triboelectric nanogenerator (RCS-TENG) that operates in a synergistic manner, utilizing both contact-separation and rotationally independent layer modes. Through structural innovation and optimization, the contact-separation mode achieves high voltage while simultaneously utilizing the independent layer mode to achieve high current output. This composite structural design enhances the system's adaptability, enabling efficient energy conversion in a variety of operating environments and overcoming the limitations of conventional designs, such as the imbalance in voltage and current output. ZnS, a wide-bandgap semiconductor material, possesses high electronegativity and a favorable electronic structure, effectively improving the material's surface charge transfer efficiency and thereby enhancing the triboelectric effect. Therefore, Ecoflex elastomer-doped ZnS serves as the friction layer, paired with a porous sponge structure, to construct the contact-separation mode triboelectric nanogenerator (EZ-TENG). A rotationally independent layer triboelectric nanogenerator (PG-TENG) is constructed using PTFE (polytetrafluoroethylene) and (GF) glass fiber as the two friction layers. PTFE, with its extremely low surface energy and excellent wear resistance, significantly reduces energy loss and increases output current. The introduction of glass fiber further enhances the mechanical strength and durability of the structure, making it suitable for high-frequency, long-term friction motion. This composite design not only breaks through the power bottleneck of traditional TENG, but also provides new ideas for efficient energy capture in complex mechanical environments.

[0026] The drive section is composed of a turbine blade structure. Compared to the previous force-bearing water scoop, this structure has the following advantages: because the blades are evenly distributed, the force applied to the blades by the water flow is more even, and the rotation process is smooth. At the same time, the blades can guide the direction of the water flow as they rotate, making the kinetic energy of the water more efficiently utilized while reducing energy loss caused by water dispersion. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the preparation of the EZ-TENG friction layer.

[0028] Figure 2 XRD characterization diagrams of ZnS and Ecoflex / ZnS.

[0029] Figure 3 Figure 1 is the COMSOL simulation diagram of EZ-TENG, where i is the simulation diagram when the two friction layers are in contact with each other; ii is the simulation diagram when the two friction layers are separated to 0.5 cm; iii is the simulation diagram when the two friction layers are separated to 3.5 cm; iv is the simulation diagram when the two friction layers slowly approach each other to 0.5 cm.

[0030] Figure 4Schematic diagram of the working principle of EZ-TENG, where i is the initial state; ii is the two friction layers in contact with each other; iii is the two friction layers starting to separate; iv is the maximum separation between the two friction layers; and v is the two friction layers slowly approaching each other.

[0031] Figure 5 The electrical output performance test results of EZ-TENG under different mass ratios of ZnS are shown in Figure 1, where (a) is the output voltage test result diagram under different mass ratios of ZnS; (b) is the output current test result diagram under different mass ratios of ZnS.

[0032] Figure 6 The following are the test results of the electrical output performance of EZ-TENG at different frequencies; (a) is the test result of the output voltage of EZ-TENG at different frequencies; (b) is the test result of the output current of EZ-TENG at different frequencies.

[0033] Figure 7 The following are the test results of the electrical output performance of EZ-TENG, where (a) is the long-term stability test result of EZ-TENG; (b) is the charging time curve of different capacitors; (c) is the voltage and current output test result under different loads; and (d) is the peak power density diagram.

[0034] Figure 8 These are the CAD drawings and physical drawings of the rotor and stator, where (a) is the CAD drawing of the rotor; (b) is the CAD drawing of the stator; (c) is the physical drawing of the rotor; and (d) is the physical drawing of the stator.

[0035] Figure 9 These are the actual pictures of the attached PTFE rotor and the attached GF stator, where (a) is the actual picture of the attached PTFE rotor; (b) is the actual picture of the attached GF stator.

[0036] Figure 10 Figure 3 is the COMSOL simulation diagram of PG-TENG, where i is the simulation diagram when PTFE is on the left electrode; ii is the simulation diagram when PTFE starts to slide from the left electrode to the right electrode; iii is the simulation diagram when PTFE quickly moves to the right electrode; and iv is the simulation diagram when PTFE moves to the right electrode.

[0037] Figure 11 Figure 2 is the working principle diagram of PG-TENG.

[0038] Figure 12 The following are the test results of the electrical output under different spacings between the PG-TENG stator and rotor: (a) is the test result of the open-circuit voltage under different spacings between the PG-TENG stator and rotor; (b) is the test result of the short-circuit current under different spacings between the PG-TENG stator and rotor.

[0039] Figure 13 The graphs show the test results of the electrical output of PG-TENG at different speeds, where (a) shows the open-circuit voltage test results of PG-TENG at different speeds; (b) shows the short-circuit current test results of PG-TENG at different speeds.

[0040] Figure 14 These are the test results of the electrical output performance of PG-TENG, where (a) is the long-term stability test result of the output voltage of PG-TENG; (b) is the long-term stability test result of the output current of PG-TENG; (c) is the voltage and current output test result under different loads; and (d) is the peak power density diagram of PG-TENG.

[0041] Figure 15 The charging time curve of PG-TENG for different capacitors.

[0042] Figure 16 The structural design diagram of RCS-TENG, where (a) is the right view of RCS-TENG; (b) is the top view of RCS-TENG; (c) is the main view of RCS-TENG; and (d) is the rear view of RCS-TENG.

[0043] Figure 17 Figure 3 shows the output test results of RCS-TENG, where (a) shows the output voltage test results of RCS-TENG at different water flow rates; (b) shows the output current test results of RCS-TENG at different water flow rates; and (c) shows the RCS-TENG lighting up the "TENG" pattern light at a flow rate of 0.7 m / s.

[0044] Figure 18 Schematic diagram of the heavy metal ion electrodeposition principle.

[0045] Figure 19 This is the circuit diagram of the rectifier and voltage regulator module.

[0046] Figure 20 This is the circuit diagram of the maximum power tracking module.

[0047] Figure 21 This is a U0-t curve measured with R = 100 kΩ, C = 10 μF, and L = 100 μH. The response approaches steady-state within 7 seconds. The inset shows a DC component of 9.12 V and a ripple of 0.01 V.

[0048] Figure 22The U0-t curve diagram measured at different resistance values ​​and the DC component and ripple diagram of the output voltage at different resistance values, where (a) is the U0-t curve diagram measured at different resistance values; (b) is the DC component and ripple diagram of the output voltage at different resistance values.

[0049] Figure 23 The U0-t curve and the DC component and ripple diagram of the output voltage are measured at different capacitance values ​​and different inductance values, where (a) is the U0-t curve measured at different capacitance values; (b) is the DC component and ripple diagram of the output voltage at different capacitance values; (c) is the U0-t curve measured at different inductance values; (d) is the DC component and ripple diagram of the output voltage at different inductance values.

[0050] Figure 24 Comparison chart of direct charging and charging of a 1 mF capacitor through a PMM circuit.

[0051] Figure 25 Diagram of the RCS-TENG-driven heavy metal ion removal platform.

[0052] Figure 26 The results of the copper ion removal experiment are shown, where (a) is a physical picture of the anode graphite and cathode titanium plate; (b) is a physical picture of Cu deposited on the cathode titanium plate at different times and a color change diagram of the solution; (c) is an EDS characterization of Cu attached to the titanium plate electrode.

[0053] Figure 27 Figure 3 is the relationship between the removal rate of Cu and time at different concentrations, different pH values, and different distances between the anode and cathode of the electrode plate. (a) is the relationship between the removal rate of Cu and time at different concentrations; (b) is the relationship between the removal rate of Cu and time at different pH values; (c) is the relationship between the removal rate of Cu and time at different distances between the anode and cathode of the electrode plate.

[0054] Figure 28 The results of the lead ion removal experiment are shown in Figure 1, where (a) is the relationship between the removal rate of Pb and time at different concentrations; (b) is a physical picture of Pb deposited on the cathode titanium plate at different times; and (c) is an EDS characterization of Pb attachment on the titanium plate electrode.

[0055] Figure 29 Figure 3 is a graph showing the relationship between the removal rate of Pb and time at different pH values ​​and different distances between the anode and cathode of the electrode plate, where (a) is a graph showing the relationship between the removal rate of Pb and time at different pH values; (b) is a graph showing the relationship between the removal rate of Pb and time at different distances between the anode and cathode of the electrode plate.

[0056] Figure 30The results of the cadmium ion removal experiment are shown in Figure 1, where (a) is a physical picture of the anode ruthenium-iridium-titanium electrode and the cathode titanium plate; (b) is a physical picture of Cd deposited on the cathode titanium plate at different times; and (c) is an EDS characterization picture of Cd attached to the titanium plate electrode.

[0057] Figure 31 Figure 3 is a graph showing the relationship between the removal rate of Cd and time at different concentrations, different pH values, and different distances between the anode and cathode of the electrode plate. (a) is a graph showing the relationship between the removal rate of Cd and time at different concentrations; (b) is a graph showing the relationship between the removal rate of Cd and time at different pH values; and (c) is a graph showing the relationship between the removal rate of Cd and time at different distances between the anode and cathode of the electrode plate.

[0058] Figure 32 This is a structural diagram of stator 1, fixed disc and stator 2 being installed on bracket 1, bracket 2 and bracket 3 respectively.

[0059] Figure 33 This is a schematic diagram of the installation sequence of each structure of the contact and separation components.

[0060] Figure 34 Schematic diagram of the structural breakdown of the contact and separation components. DETAILED DESCRIPTION

[0061] Materials used in the embodiments of the present invention:

[0062] 1. Zinc sulfide (ZnS, 99.99%) was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0063] 2. Ecoflex silicone (net weight 0.90 kg) was purchased from Smooth-On (USA). To use Ecoflex silicone: Thoroughly mix Ecoflex silicone gels A and B in a 1:1 mass ratio, ensuring a uniform mixture.

[0064] 3. PTFE (thickness: 0.01 mm) was purchased from Shenzhen Le Shangjia Technology Co., Ltd., and GF (thickness: 0.15 mm) was purchased from Xiongxian Yujin Building Materials Co., Ltd.

[0065] Example 1

[0066] like Figure 1As shown in FIG, a copper electrode coated with an Ecoflex / ZnS film was prepared: ZnS powder was added to Ecoflex silica gel and stirred, with the ZnS powder accounting for 9 wt% of the total mass of the ZnS powder and Ecoflex silica gel to obtain a uniform mixture. The obtained mixture was evenly coated on the surface of a wooden board on which a copper electrode had been pre-laid by spin coating at a speed of 1000 r / min, with a coating thickness of 0.1 mm. The spin-coated sample was transferred to a vacuum drying oven for curing treatment at a curing temperature of 60°C and a curing time of 4 h to obtain a copper electrode coated with an Ecoflex / ZnS film.

[0067] Example 2

[0068] Preparation of a copper electrode coated with Ecoflex / ZnS film: Compared with Example 1, except that the ZnS powder accounts for 0 wt% of the total mass of the ZnS powder and Ecoflex silica gel, other steps and process parameters are the same.

[0069] Example 3

[0070] Preparation of a copper electrode coated with Ecoflex / ZnS film: Compared with Example 1, except that the ZnS powder accounts for 3 wt % of the total mass of the ZnS powder and Ecoflex silica gel, other steps and process parameters are the same.

[0071] Example 4

[0072] Preparation of a copper electrode coated with Ecoflex / ZnS film: Compared with Example 1, except that the ZnS powder accounts for 6 wt % of the total mass of the ZnS powder and Ecoflex silica gel, other steps and process parameters are the same.

[0073] Example 5

[0074] Preparation of a copper electrode coated with Ecoflex / ZnS film: Compared with Example 1, except that the ZnS powder accounts for 11 wt % of the total mass of the ZnS powder and Ecoflex silica gel, other steps and process parameters are the same.

[0075] Example 6

[0076] Preparation of a copper electrode coated with Ecoflex / ZnS film: Compared with Example 1, except that the ZnS powder accounts for 13 wt % of the total mass of the ZnS powder and Ecoflex silica gel, other steps and process parameters are the same.

[0077] 1. Performance testing of a silicone / zinc sulfide-based contact-separation triboelectric nanogenerator (EZ-TENG)

[0078] 1.1 Characterization of friction layer material composite films

[0079] The present invention characterizes the Ecoflex / ZnS friction layer film mainly by X-ray diffraction (XRD). The XRD diffraction patterns of ZnS and Ecoflex / ZnS are as follows Figure 2 The diffractometer was used (Cu Kα, λ = 1.5418 Å) at 10-60 o The diffraction peak of ZnS powder is located at 2θ=26.67 o , 28.43 o , 30.46 o , 47.34 o and 56.21 o , corresponding to the (010), (002), (011), (110), and (112) crystal planes, and all diffraction peaks are consistent with those reported in the literature. From the figure, we can see that ZnS is well composited on Ecoflex, and there are no other impurity peaks, which indicates that the Ecoflex / ZnS friction layer was successfully prepared.

[0080] 1.2 Friction layer material performance simulation and working principle

[0081] The positive friction layer of EZ-TENG is Ecoflex / ZnS film, and the negative friction layer is sponge. Figure 3 As shown in the figure, the present invention simulates the change in the potential distribution of the EZ-TENG during a working cycle using COMSOL Multiphysics software. From the initial full contact state to separation, complete separation, and initial contact, the potential difference gradually forms and reaches a maximum, and finally begins to decrease as contact gradually increases. This change in potential difference is the basis for the TENG to convert mechanical energy into electrical energy. Through COMSOL simulation, the change in potential distribution can be intuitively seen, which helps to understand and optimize the design of the EZ-TENG.

[0082] Figure 4The working principle of the Ecoflex / ZnS-based triboelectric nanogenerator (EZ-TENG) is demonstrated. Initially, the Ecoflex / ZnS positive friction layer and the sponge negative friction layer are separated. The EZ-TENG is not moving, and no charge is accumulated. When the two friction layers of the EZ-TENG come into contact, electrons on the friction layer surfaces are transferred due to the different triboelectric series of the two friction layers. The sponge layer then acquires electrons from the Ecoflex / ZnS layer. At this point, the Ecoflex / ZnS layer becomes positively charged, while the sponge layer becomes negatively charged. Because the charge distribution on the two friction layers is symmetrical, no current flows in the circuit. As the Ecoflex / ZnS layer and the sponge layer gradually separate, electrostatic induction redistributes the charge, and the electric field begins to change, increasing the potential difference between the upper and lower layers. This change in potential difference causes electrons to flow along the external circuit, forming a current. The potential difference is maximized when the two friction layers are separated to their maximum distance. Then, when the two friction layers slowly come into contact, currents flow in opposite directions in the external circuit. This process is then repeated, and the EZ-TENG generates alternating current.

[0083] 1.3 Output performance test of contact-separation triboelectric nanogenerator

[0084] In order to make the EZ-TENG have the best electrical output performance, the present invention regulates the mass ratio of the Ecoflex / ZnS friction layer material. First, Examples 1-6 prepared Ecoflex / ZnS friction layer films with different mass fractions (0 wt%, 3 wt%, 6 wt%, 9 wt%, 11 wt% and 13 wt%) for electrical output testing. The thickness of these films remained almost the same. When the contact-separation motion frequency was 5 Hz, the electrical output signal was tested. Figure 5As shown in Figures (a) and (b), the open-circuit voltage and short-circuit current output values ​​of the TENG are highest when the ZnS mass fraction in the Ecoflex / ZnS film is 9 wt%, with an open-circuit voltage of 743 V and a short-circuit current of 113 μA. As the ZnS mass fraction in the Ecoflex / ZnS film increases from 0 wt% to 9 wt%, both the open-circuit voltage and short-circuit current show an upward trend. This is because appropriate ZnS doping can enhance the dielectric constant and surface charge density of Ecoflex. ZnS doping can introduce localized energy levels, enhancing charge capture and thus improving charge transfer efficiency during friction. The high dielectric constant of ZnS helps reduce charge recombination and promotes charge separation and accumulation at the interface, thereby improving output performance. As the ZnS mass fraction in the Ecoflex / ZnS film continues to increase, the open-circuit voltage and short-circuit current show a downward trend. When the doping concentration is too high, ZnS particles may aggregate within the Ecoflex matrix, resulting in uneven charge distribution on the friction layer surface and rapid charge loss and leakage. Excessive ZnS doping also increases interfacial resistance, reducing electron transfer efficiency. Therefore, the present invention selected a 9% mass fraction of ZnS for subsequent experiments.

[0085] In order to ensure that EZ-TENG still has efficient and stable output at low frequency, its electrical output was tested under the conditions of 1 Hz to 5 Hz. Figure 6 Figures (a) and (b) show a slight upward trend in voltage with increasing frequency. Current increases rapidly with increasing frequency. As can be seen from the figures, even at a low frequency of 1 Hz, the EZ-TENG maintains excellent voltage and current output, with an open-circuit voltage of 512 V and a short-circuit current of 57 μA.

[0086] In order to verify the long-term stability of EZ-TENG, Figure 7 Figure (a) shows the long-term stability of EZ-TENG for 2000 s. It can be seen from the test graph that its output voltage has almost no change during the 2000 s test, proving its excellent output stability. By connecting different capacitors (10 μF, 22 μF, 47 μF, 100 μF, 220 μF and 470 μF) to the bridge rectifier circuit, the EZ-TENG is used to charge it. Figure 7 As can be seen in Figure (b), a 10 μF capacitor can reach 20 V in about 50 s. Its charging time is 11 times shorter than that of EPT-TENG, which shows that the electrical output of EZ-TENG has been greatly improved compared with previous work. Figure 7 Figure (c) shows the voltage and current under different loads. Figure 7Figure (c) shows the voltage and current under different loads. The peak power density of EZ-TENG is shown in Figure 5. Figure 7 As shown in Figure (d). When the load resistance is 5 MΩ, the power density reaches the maximum, and the peak power density is 2.56 W / m 2 Its peak power density is 1.7 times higher than that of EPT-TENG, which fully demonstrates the excellent output performance of EZ-TENG.

[0087] Example 7

[0088] The sliding friction assembly includes a rotor 2, a stator 2, and a bracket 3. The main bodies of the rotor 2 and the stator 2 are PCBs. Grid-shaped copper electrodes are evenly arranged on the rotor 2 and the stator 2. A PTFE layer is attached to the copper electrode of the rotor 2, and a GF film is attached to the copper electrode of the stator 2. The PTFE layer and the GF film are in close contact.

[0089] A through hole is provided at the center of rotor 2 and the center of stator 2. The rotating shaft passes through the through hole of rotor 2 and is fixedly connected to rotor 2. The rotating shaft passes through the through hole of stator 2. The aperture of the through hole of stator 2 is larger than the diameter of the rotating shaft. Stator 2 is fixedly mounted on bracket 3, and bracket 3 is fixedly mounted on the base.

[0090] The shape of rotor 2 is a circle with a diameter of 200 mm and a 6 mm through-hole in the center. The copper electrode on rotor 2 is set as a ring with an outer diameter of 200 mm and an inner diameter of 70 mm centered on the center of rotor 2. The number of grids is 30 and evenly distributed (the ring is divided into 60 grids, and a grid copper electrode is set every other grid); the shape of stator 2 is a square with a side length of 200 mm and a 8 mm through-hole in the center. The copper electrode on the stator is set as a ring with an outer diameter of 200 mm and an inner diameter of 70 mm centered on the center of stator 2. The number of grids is 30 pairs and evenly distributed (the ring is divided into 60 grids, and a grid copper electrode is set every other grid). One grid on each side of the copper electrode on the stator is extended as a terminal.

[0091] The thickness of the PTFE layer is 0.01 mm, and the PTFE layer has the same shape as the rotor 2, and completely covers the rotor 2 when pasted; the thickness of the GF membrane is 0.15 mm, and the GF membrane has the same shape as the stator 2, and completely covers the stator 2 when pasted.

[0092] The CAD drawings of the rotor 2 without PTFE layer and the stator 2 without GF film are as follows: Figure 8 The actual pictures of rotor 2 without PTFE layer and stator 2 without GF membrane are shown in Figures (a) and (b). Figure 8 As shown in Figures (c) and (d), the actual images of rotor 2 and stator 2 are as follows Figure 9 As shown in Figures (a) and (b).

[0093] 2. Performance test of glass fiber-PTFE based rotary triboelectric nanogenerator

[0094] 2.1 Performance simulation and working principle of the rotary triboelectric nanogenerator

[0095] In order to verify and explain the working mechanism of PG-TENG, the present invention uses COMSOL Multiphysics finite element simulation software to simulate and analyze the potential distribution of PG-TENG in different states. Figure 10 As shown in the figure, the electrostatic equilibrium is disrupted during the sliding process. As the PTFE material moves, the potential difference between the two copper electrodes changes, with the voltage generated ranging from -400 V to 400 V. As the PTFE film slides from the left electrode to the right electrode, the electrode voltage increases toward the left, and vice versa.

[0096] The working principle diagram of PG-TENG is as follows Figure 11 As shown in the figure, during friction, because PTFE is more susceptible to electron absorption than GF, the PTFE surface acquires a negative charge, while the GF surface acquires a positive charge. The charge carried by the copper electrode changes as the PTFE slides, and electrostatic induction generates equal and opposite charges on the two electrodes of the grid. When the slider begins to slide, it moves from the left electrode to the right. As the overlap area of ​​the PTFE with the left electrode decreases and the overlap area with the right electrode increases, electrons flow from the left electrode to the right electrode through the external load circuit, generating an electric current. When the PTFE moves to the right electrode, an equal amount of positive charge is generated on the right electrode. As the PTFE moves to the left, charge transfer continues in the external circuit, and current flows from the right electrode to the left through the external load. This reciprocating motion of the PTFE film between adjacent electrodes generates alternating current in the PG-TENG.

[0097] 2.2 Output performance test of rotary triboelectric nanogenerator (PG-TENG)

[0098] In order to explore the optimal operating state of PG-TENG, the electrical output performance of different distances between its rotor and stator was investigated. Figure 12Figures (a) and (b) show the open-circuit voltage and short-circuit current at different spacings between the stator and rotor. As can be seen from the figure, as the spacing increases, the open-circuit voltage and short-circuit current show a downward trend. This is because when the stator and rotor are in contact with each other, the contact area between PTFE and GF is large, the triboelectric effect maximizes the charge transfer, and the surface charge density reaches a peak. At this time, the contact area between PTFE and GF is the largest, the charge transfer between the positive and negative friction layers is most complete, the positive and negative charges are significantly separated, and the voltage reaches its maximum value. As the spacing increases, the actual contact area decreases, the charge transfer efficiency decreases, the surface charge density decreases, and the output voltage decreases. Although PTFE and GF are not in direct contact, they still have a high open-circuit voltage and short-circuit current output. This is because as long as the vertical spacing is much smaller than the relative displacement of the two electrodes, the sliding of charges on the PTFE film will still cause a large portion of the charge to flow.

[0099] In addition, external factors have a great influence on the electrical output performance of PG-TENG. For the rotational mode triboelectric nanogenerator, its electrical output performance is related to the rotation speed. Figure 13 As shown in Figures (a) and 4-13-b, the open-circuit voltage and short-circuit current of the PG-TENG show a linear increase as the rotational speed increases from 150 r / min to 350 r / min. This phenomenon is primarily due to the accelerated charge transfer rate as the rotational speed increases. Generally speaking, the output voltage of a TENG is independent of the rotational speed and typically remains constant. However, during PG-TENG rotation, due to slight instabilities in motor operation, the PG-TENG rotor can achieve greater rotational torque. As the speed and torque increase, the contact between the PTFE and the GF becomes closer. Due to the fluffy and porous structure of the GF, the closer contact further compresses the GF, increasing the contact area and thus the surface charge density. This process further enhances the output performance of the PG-TENG. At a rotational speed of 350 r / min, the open-circuit voltage reaches 693 V and the current reaches 225 μA.

[0100] In order to ensure the smooth operation of PG-TENG during operation, the output voltage of PG-TENG was tested continuously for 700 s. The experimental results are shown in the figure. Figure 14 As shown in Figure (a). From the experimental results, it can be seen that during the 700 s continuous test process, its output voltage remains stable. The output current of PG-TENG was tested continuously for 800 s. The experimental results are shown in Figure (a). Figure 14 As shown in Figure (b). From the test results, it can be seen that during the entire 800 s continuous operation process, its output current remains stable. Figure 14As shown in Figure (c), when the rotation speed is fixed at 300 r / min, as the external load resistance increases, the output current of PG-TENG gradually decreases, while the peak value of the output voltage continues to rise. Finally, when the load resistance is set to 3 MΩ, the maximum peak power density of PG-TENG reaches 11.69 W / m 2 ,like Figure 14 As shown in Figure (d), its maximum peak power is increased by about 4.6 times compared to EZ-TENG, which demonstrates its excellent electrical output performance.

[0101] Due to the uncertainty of TENG output, energy storage devices such as capacitors are often required. Therefore, the overall power output capability of PG-TENG for different capacitors (22 μF, 33 μF, 47 μF, 110 μF, 220 μF and 470 μF) was studied when the speed was 300 r / min. The experimental results are shown in Figure 2. Figure 15 As shown, the PG-TENG can rapidly charge a 22 μF capacitor to 34 V in 25 s. It can also rapidly charge a 470 μF capacitor to 3.7 V in 50 s. The experiments demonstrate that the PG-TENG is capable of quickly charging and storing both large and small capacitors. In subsequent experiments, selecting the right capacitor will effectively improve the efficiency of the entire system to meet diverse needs.

[0102] Example 8

[0103] A triboelectric nanogenerator for fluid energy harvesting (RCS-TENG) was prepared using the copper electrode coated with Ecoflex / ZnS film prepared in Example 1 and the sliding friction component prepared in Example 7.

[0104] like Figures 32-34 As shown, the triboelectric nanogenerator for fluid energy harvesting includes: a base, two support plates, a forced turbine blade, a rotating shaft, a contact and separation component, and a sliding friction component;

[0105] The support plates are fixedly mounted on both sides of the base, and bearings are respectively embedded on the top ends of the support plates. The rotating shaft is rotatably connected to the support plates through the bearings. The forced turbine blades include a mounting portion and a plurality of blades, and the plurality of blades are fixedly connected to the outer periphery of the mounting portion. The forced turbine blades are fixedly mounted on one end of the rotating shaft through the mounting portion, and the contact and separation assembly and the sliding friction assembly are respectively mounted on the rotating shaft.

[0106] The contact and separation assembly includes a rotor 1 inlaid with four universal balls, a balloon membrane, a fixed disc with an inlay hole, a copper electrode coated with an Ecoflex / ZnS film, a copper electrode covered with a sponge film, a gasket, a stator 1, a bracket 1, and a bracket 2. The gasket and the copper electrode covered with the sponge film are respectively fixedly connected to the stator 1. The thickness of the gasket is greater than that of the copper electrode covered with the sponge film. The copper electrode coated with the Ecoflex / ZnS film is inlaid in the inlay hole with the fixed disc. The Ecoflex / ZnS film is close to the sponge film. The balloon membrane covers the surface of the fixed disc. The universal balls are in close contact with the balloon membrane.

[0107] The centers of rotor 1, the balloon membrane, the fixed disk, and stator 1 are provided with through holes. The rotating shaft passes through the through hole in the center of rotor 1 and is fixedly connected to rotor 1. The rotating shaft passes through the through holes in the center of the balloon membrane, the fixed disk, and stator 1 in sequence. The apertures of the through holes of the balloon membrane, the fixed disk, and stator 1 are larger than the diameter of the rotating shaft. Stator 1 is fixedly mounted on bracket 1, the fixed disk is fixedly mounted on bracket 2, and brackets 1 and 2 are respectively fixedly mounted on the base.

[0108] The shape of rotor one is a circle with a diameter of 200 mm, a through hole of 6 mm in the center, and the material is acrylic with a thickness of 12 mm; the diameter of the universal ball is 18 mm, the material is bearing steel, and the height of the universal ball protruding from rotor one is 5 mm; the shape of the balloon membrane is a circle with a diameter of 200 mm, a through hole of 8 mm in the center, the material is latex, and the thickness is 0.04 mm; the shape of the fixed disk is a circle with a diameter of 200 mm, a through hole of 8 mm in the center, the material is acrylic, and the thickness is 4 mm, and the shape of the inlay holes is a plurality of squares with a side length of 5 cm; the shape of the copper electrode coated with Ecoflex / ZnS film is a plurality of squares with a side length of 5 cm, wherein the thickness of the copper electrode layer is 0.065 mm, and the thickness of the Ecoflex / ZnS film is 0.1 mm; the shape of the copper electrode covered with sponge film is 4 squares with a side length of 5 cm, wherein the thickness of the copper electrode layer is 0.065 mm, and the thickness of the sponge film is 0.5 mm; the gasket is in the shape of a long strip, made of acrylic, and 5 mm thick; the shape of stator one is a circle with a diameter of 200 mm, with an 8 mm through hole in the center, and is made of acrylic, and 5 mm thick; when the universal ball does not rotate into the inlay hole, the distance between the sponge film and the Ecoflex / ZnS film is 5 mm, and the positions of the four copper electrodes coated with Ecoflex / ZnS film and the four copper electrodes covered with sponge film correspond one to one. When the universal ball rotates into the inlay hole, the positions of the four universal balls and the four inlay holes correspond one to one.

[0109] The base, support plate, bracket one, bracket two and bracket three are all made of wood. The base is 35 cm long and 20 cm wide. The support plate is trapezoidal, with a lower base length of 14 cm, an upper base length of 5 cm and a height of 14 cm. Stator one is embedded in bracket one, and the fixed disc is embedded in bracket two. Bracket one and bracket two are 140 mm high and 200 mm wide. Stator two is embedded in bracket three. Bracket three is 140 mm high and 220 mm wide. The length of the rotating shaft is 305 mm, the diameter is 5 mm, and the material is carbon steel.

[0110] The overall structural design of RCS-TENG is shown in the figure below. Figure 16 The right side view of RCS-TENG is shown in Figure 16 As shown in Figure (a), the various views of RCS-TENG are as follows Figure 16 As shown in Figures (b) and (c).

[0111] 3. Performance test of rotation-contact separation friction nanogenerator

[0112] 3.1 Output performance test of rotation-contact separation friction nanogenerator

[0113] The RCS-TENG operates as follows: When water strikes the device's turbine blades, the flow induces rotation, further driving the connected shaft to rotate synchronously. The shaft's rotation drives the attached rotor, which primarily consists of two components: contact and separation, and rotational friction. The contact and separation portion of the rotor is embedded with a universal ball. As the rotor rotates, the universal ball slides along the balloon membrane on the stator surface. When it reaches the hollow region of the contact and separation portion, the force exerted on the Ecoflex / ZnS friction layer pushes downward, forcing it into close contact with the underlying sponge friction layer. At this point, electron transfer occurs at the friction interface, achieving charge separation. As the rotor rotates further, the universal ball leaves the hollow region. As the external force disappears, the Ecoflex / ZnS friction layer recovers its original shape due to its own elasticity and separates from the sponge friction layer, completing a complete contact-separation cycle. In this system, four EZ-TENG units are connected in series. As the rotor continues to rotate, the contact-separation cycle repeats, continuously outputting electrical energy. The rotor in the rotating friction section rotates with the shaft, and the PTFE material continuously slides and rubs against the GF material, generating alternating current. The contact and separation section is connected in parallel with the rotating friction section to increase its current output.

[0114] Next, the electrical output performance of RCS-TENG under different flow rate conditions was tested. Figure 17 Figure (a) and Figure 17Figure (b) shows the changes in output voltage and output current as the water flow rate increases from 0.5 m / s to 1.3 m / s. Experimental results show that the open-circuit voltage and short-circuit current of the RCS-TENG both increase with increasing flow rate. This phenomenon is primarily attributed to the increased impact force of the water flow on the stressed water scoop, which accelerates its rotational speed, thereby simultaneously increasing the rotational speed of the shaft. Because the shaft is connected to the rotor, the rotor's rotational speed also increases, further affecting the force exerted by the universal ball embedded in the rotor on the Ecoflex / ZnS friction layer. As the rotor rotates faster, the periodic contact pressure of the universal ball on the friction layer increases, and the rotational speed of the rotating friction part increases, thereby enhancing the triboelectric effect and increasing the overall output voltage and current. Furthermore, higher flow rates not only accelerate the motion of the entire system but also reduce the energy loss that can occur due to low-speed operation, enabling the RCS-TENG to perform more efficient energy conversion at higher flow rates. Therefore, within the test range, the open circuit voltage and short circuit current of RCS-TENG both increase steadily with the increase of water flow velocity, verifying the response characteristics of the system to flow velocity changes. At a flow velocity of 1.3 m / s, its voltage can reach 702 V and its current can reach 255 μA. Figure 17 As shown in Figure (c).

[0115] Conclusion: This paper constructs a hybrid triboelectric nanogenerator (RCS-TENG) that combines contact-separation mode with independent layer mode, achieving both high voltage and high current output performance. The contact-separation mode material is prepared by spin coating Ecoflex / ZnS film. When the load resistance is 5 MΩ, its power density reaches the maximum, with a peak power density of 2.56 W / m 2 It is 1.7 times higher than EPT-TENG. Under low-frequency conditions of 1 Hz, the open-circuit voltage of EZ-TENG can reach 512 V and the short-circuit current can reach 57 μA. When the speed of PG-TENG is 350 r / min, its open-circuit voltage can reach 693 V and the current can reach 225 μA. The two modes of TENG complement each other and work synergistically under low-frequency and high-frequency conditions. This composite design not only breaks through the power limitations of traditional TENG, but also provides a new idea for achieving efficient energy capture in complex mechanical environments. Compared with previous studies, the present invention has achieved significant improvement in electrical output performance.

[0116] 4. Application of triboelectric nanogenerator for fluid energy harvesting in heavy metal ion removal.

[0117] This paper develops a triboelectric nanogenerator (TENG) combined with a power management circuit (PMM) to construct a heavy metal ion electrodeposition system. The RCS-TENG combined with the PMM circuit was chosen because it offers the best electrical output performance. The power management circuit design reduces the TENG's output voltage ripple, improves stability during the electrodeposition process, and reduces heat loss during operation. The stable output voltage ensures uniformity and controllability of the electrodeposition reaction.

[0118] 4.1 Heavy Metal Ion Removal Platform Based on Triboelectric Nanogenerators

[0119] 4.1.1 Principle of heavy metal ion electrodeposition removal

[0120] The principle of removing heavy metal ions by electrodeposition is as follows Figure 18 shown.

[0121] 4.1.2 Power Management Circuit Design and Optimization

[0122] The circuit diagram of the power management circuit is as follows Figure 19 The entire power management circuit is mainly composed of two parts: voltage regulation and current stabilization module and maximum power tracking module. Figure 20 As shown. The power management module capacitors, inductors, and resistors were tested in detail to determine their optimal output, ensuring that the power management module can provide efficient and stable power output under various working environments. The power management module is based on maximum energy transfer strategy, DC step-down conversion, and self-management mechanism. Figure 21 Figure 2 shows the U0-t curve measured under the conditions of R = 100 kΩ, C = 10 μF, and L = 100 μH. The output voltage continuously rises from its initial state and reaches a steady state within 7 seconds. The enlarged view in the inset shows that the DC component at steady state is 9.12 V, with a ripple of 0.01 V. This is consistent with theoretical studies of power management circuits in the literature and is very close to the voltage requirements of traditional electronic devices and the electrical output requirements of electrolytic cells.

[0123] When the circuit is replaced with resistors of different values, under the conditions of resistance C = 5 μF and inductance L = 100 μH, the output voltage in steady state is as follows Figure 22 As shown in Figure (a), the DC component and ripple value of the output voltage under different resistance values ​​are Figure 22 This is summarized in Figure (b). It can be clearly seen that as the resistance increases, the DC component increases, while the ripple generally decreases. Furthermore, as the resistance value increases, the output voltage increases accordingly. To better facilitate electrodeposition experiments and meet the driving voltage requirements for heavy metal ions, R = 100 kΩ was selected.

[0124] In a PMM circuit, capacitance and inductance are important parameters, and this invention discusses these parameters in detail. Figure 23 Figures (a) and (b) show the output voltage characteristics in steady state with different capacitance values ​​under the conditions of resistance R = 100 kΩ and inductance L = 100 μH; Figure 23 Figures (c) and (d) show the steady-state output voltage characteristics for varying inductance values ​​with a resistance of 100 kΩ and a capacitance of 10 μF. The experimental results clearly show that changes in capacitance and inductance have little effect on their DC components, as they do not consume energy. However, the ripple decreases significantly with increasing capacitance and inductance, attributed to their energy storage and filtering properties.

[0125] Figure 24 The charging curves of a 1 mF capacitor charged directly by an RCS-TENG and through a PMM circuit at a flow rate of 0.7 m / s were compared. The experimental results show that within the same time, the RCS-TENG managed by the PMM circuit can charge the capacitor to a higher voltage during the charging process, confirming the advantages of the PMM power management circuit.

[0126] 4.1.3 Construction of heavy metal ion removal platform

[0127] Heavy metal ion removal platform such as Figure 25 As shown in the figure, it mainly consists of three parts: RCS-TENG, power management circuit and electrodeposition reaction cell. This platform combines the self-powered characteristics of converting mechanical energy into electrical energy with the application of electrochemical reactions to form an innovative water treatment technology. The triboelectricity generated by RCS-TENG is improved through the PMM power management circuit to improve its electrical output performance. At the same time, its electrical output is rectified, stored and regulated to ensure that it can provide a smooth and stable power output to drive the electrochemical reaction in the electrodeposition reaction cell. Driven by the power management circuit, the electrodes in the electrodeposition cell begin to work. The heavy metal ions in the solution undergo a reduction reaction at the cathode to form metal deposits on the surface of the cathode electrode plate, thereby achieving the effect of removing heavy metal ions.

[0128] 4.2 Study on the Electrodeposition Removal of Heavy Metal Ions Based on Rotation-Contact Separation Triboelectric Nanogenerator

[0129] 4.2.1 Copper ion removal experiment

[0130] First, with the initial pH value of the solution at 4, the voltage input at 9.12 V, and the distance between the anode and cathode plates controlled at 20 mm, a series of CuSO4 solutions with different concentrations (1.5 g / L, 2 g / L, 2.5 g / L, and 3 g / L) were prepared under these conditions. The electrode materials selected were graphite as the anode and titanium plate as the cathode. The actual physical diagram is shown in the figure. Figure 26 As shown in Figure (a). Figure 26 Figure (b) shows the actual picture of Cu deposited on the cathode titanium plate at different times in 2.5 g / L CuSO4 solution and the color change of the solution. EDS characterization of the deposited adhering substances on the electrode is performed, such as Figure 26 As shown in Figure (c), it can be clearly seen from the characterization analysis that the deposit is Cu.

[0131] Figure 27 Figure (a) shows the relationship between the removal rate of copper and time at different concentrations. The experimental results show that the higher the copper ion concentration, the higher the copper removal efficiency. When the copper ion concentration is 1.5 g / L, the electrodeposition effect is poor, and the copper removal rate is 62%; when the copper concentration is 2 g / L, the electrodeposition effect is the best, and the removal rate can reach 80%; but when the copper ion concentration increases to 3 g / L, the copper removal rate decreases. The main reason is that when the copper in the solution 2+ When the concentration is low, as the reaction proceeds, Cu 2+ The concentration gradually decreases, resulting in a decrease in the diffusion rate and a concentration polarization phenomenon, so the removal rate of Cu is low. At higher concentrations, the total resistance of the electrochemical system decreases and the conductivity of the solution increases, which promotes the electrochemical reaction. However, if the concentration is too high, the distance between ions is shortened, resulting in an increase in the interaction force between ions, increasing the resistance between ions, slowing down the movement of ions, and thus affecting the removal effect of copper. During the removal process, as the reaction time increases, the removal rate of Cu gradually increases, and the initial removal rate is faster, and then tends to be stable. This is because during the electrodeposition process, the conductivity of the solution is related to the concentration of metal ions, and Cu 2+ As the concentration increases, the conductivity increases, which helps Cu 2+ Migrate to the cathode, thereby accelerating the reaction and reducing energy consumption. As the reaction continues, the metal ions in the solution gradually precipitate on the cathode surface, causing the copper ion concentration in the solution to continue to decrease. 2+ When the concentration decreases, the number of metal ions available on the cathode surface decreases, making the electrolysis reaction more difficult. + and Cu 2+ A competitive reaction begins on the cathode surface, H + is preferentially reduced to generate H2, while Cu 2+ The reduction efficiency of Cu is reduced, resulting in a large amount of H2 precipitation from the electrode surface. The precipitation of H2 not only affects the2+ The removal efficiency is low, which further increases the energy consumption of the system. Since the H2 precipitation process consumes electricity, the system energy efficiency is reduced, resulting in an increase in the overall energy consumption of the electrolysis process, thereby reducing the copper removal effect and the overall electrolysis efficiency.

[0132] The pH of the solution is very important for the removal process. Different pH values ​​will lead to different hydrogen ion concentrations in the solution, which will have different effects on the reaction process. Figure 27 Figure (b) shows the relationship between the removal rate of Cu and reaction time at different pH values. 2+ Cu(OH)2 precipitation will occur in alkaline solutions, so the experiments were conducted at pH values ​​of 3, 4, and 5. The solution concentration was 2.5 g / L, the voltage was 9.12 V, and the spacing between the plates was 20 mm. When the pH value of the solution was 3, the copper removal rate was the lowest. As the pH value increased, the removal rate continued to increase. When the pH value was too low, the H in the solution + The content is high, and a large amount of hydrogen will be generated at the cathode during the reaction, which will inhibit the deposition of copper. As the pH value continues to increase, the H + The concentration of Cu in the solution decreases, and the hydrogen evolution reaction weakens. 2+ The reduction reaction is the dominant reaction, so the removal efficiency of Cu will be improved.

[0133] The distance between the anode and cathode electrode plates has a certain influence on the removal rate of Cu. Figure 27 Figure (c) explores the relationship between the removal rate of Cu and time at different distances between the graphite anode and the titanium plate cathode. At this time, the experimental conditions are maintained at a solution concentration of 2.5 g / L and a pH value of 5. Comparing the experimental results, it can be found that when the distance between the two electrode plates is 20 mm, the removal rate is the best. As the distance between the electrode plates increases, the removal rate shows a downward trend. This is because when the distance between the electrode plates increases, the flow rate of the electrolyte will increase, which will promote the convection and diffusion of ions in the solution, strengthen the mass transfer between heavy metal ions, and the efficiency of electrodeposition will increase. When the distance is too small, it will cause Cu 2+ The reaction is not sufficient, thus reducing the electrodeposition efficiency. When the distance is too large, Cu 2+ It takes a longer migration path to reach the cathode. At the same time, the distance between the plates is too large, the electric field strength is reduced, and the efficiency of electrodeposition is reduced.

[0134] 4.2.2 Lead ion removal experiment

[0135] In order to explore the removal effect of lead ions at different concentrations, a series of Pb(CH3COO)2 solutions with different concentrations (1.5 g / L, 2 g / L, 2.5 g / L, and 3 g / L) were prepared under the following conditions: the initial pH value of the solution was 4, the voltage input was 9.12 V, and the distance between the anode and cathode plates was controlled at 20 mm. Graphite was selected as the anode and titanium plate as the cathode. Figure 28 Figure (a) shows the relationship between lead removal rate and time. Figure 28 Figure (b) shows the actual picture of Pb deposited on the cathode titanium plate at different times in a 2.5 g / L Pb(CH3COO)2 solution and the color change of the solution. The experimental results show that when the solution concentration is 2 g / L, the Pb removal rate is as high as 82.7%. At this time, the concentration is moderate, which not only provides sufficient driving force for ion migration, but also avoids the concentration polarization phenomenon caused by excessive concentration. When the concentration is 1.5 g / L, the Pb removal rate is the lowest. This is because at low concentrations, as the reaction proceeds, Pb 2+ The concentration gradually decreases, resulting in a decrease in diffusion rate and concentration polarization, which ultimately reduces the removal efficiency of Pb. 2+ When the concentration is too high, the distance between ions is shortened, and the interaction force between ions increases. Therefore, the resistance to the mutual movement of ions increases, and the movement speed slows down, making the removal effect of Pb worse. At the same time, side reactions may be enhanced at high concentrations, further affecting the removal rate. EDS characterization of the deposits on the electrode, such as Figure 28 As shown in Figure (c), it can be clearly seen from the characterization analysis that the sediment is Pb.

[0136] The reaction conditions are: Pb(CH3COO)2 solution concentration of 2 g / L, electrode plate spacing of 20 mm, and input voltage of 9.12 V. Under these conditions, the relationship between the removal rate of Pb and time at different pH values ​​was explored. The experimental results are as follows: Figure 29 As shown in Figure (a), the experimental results show that the removal efficiency decreases with the increase of pH value. This is because when the acidity of the solution is strong, the H + The content is high, the mass transfer rate of hydrogen is high, the overpotential of H2 precipitation caused by concentration polarization phenomenon is low, the reaction rate of hydrogen evolution is fast, and the hydrogen precipitation ability is strong at this time. 2+ Therefore, the lower the pH value, the lower the removal rate of Pb. When the pH value is 5, Pb 2+ The main reaction is the precipitation of Pb, and the hydrogen evolution reaction has little effect on it. At this time, the Pb removal rate is the highest, reaching 86.9%.

[0137] Figure 29Figure (b) explores the relationship between the removal rate of Pb and time at different distances between the graphite anode and the titanium plate cathode under the experimental conditions of a solution concentration of 2 g / L and a pH value of 5. The experimental results show that when the distance between the two electrode plates is 20 mm, the removal rate is optimal. As the distance between the electrode plates increases, the removal rate shows a downward trend. This is because when the distance between the electrode plates increases, the flow rate of the electrolyte will accelerate, which will promote the convection and diffusion of ions in the solution, enhance the mass transfer between heavy metal ions, and improve the efficiency of electrodeposition. When the distance is too small, it will cause Pb 2+ The reaction is insufficient, thus reducing the electrodeposition efficiency. When the distance is too large, Pb 2+ It takes a longer migration path to reach the cathode. At the same time, the distance between the plates is too large, the electric field strength is reduced, and the electrodeposition efficiency is reduced.

[0138] 4.2.3 Cadmium ion removal experiment

[0139] This removal system was used to investigate the effectiveness of cadmium ion removal at varying concentrations, pH levels, and spacing between electrode plates. The ruthenium-iridium-titanium electrode is an inert metal oxide electrode with extremely high corrosion resistance in acidic solutions containing Cl⁻, maintaining long-term electrode surface activity. Titanium electrodes form a dense TiO₂ passivation film in Cl⁻-containing solutions. This film does not affect the cadmium reduction reaction, and the titanium electrode has moderate conductivity. Therefore, the ruthenium-iridium-titanium electrode was selected as the anode, and titanium as the cathode. Figure 33 Figure (a) is a physical picture of the electrode. Figure 33 Figure (b) shows the actual images of Cd deposited on the cathode titanium plate at different times. Figure 33 Figure (c) shows the EDS characterization of the deposited attachments on the electrode. It can be clearly seen from the characterization analysis that the deposits are Cd.

[0140] In order to investigate the effect of different concentrations of Cd 2+ To achieve the desired removal effect, a series of CdCl2 solutions with different concentrations (1.5 g / L, 2 g / L, 2.5 g / L, and 3 g / L) were prepared under the following conditions: an initial pH value of 5, a voltage input of 9.12 V, and a distance between the anode and cathode plates of 20 mm. The experimental results are shown in Figure 2. Figure 31 The experimental results show that the removal rate of Cd increases with the increase of concentration. When the solution concentration is 3 g / L, the removal rate of Cd reaches the highest of 74.7%.

[0141] The reaction conditions are CdCl2 solution concentration of 3 g / L, electrode plate spacing of 20 mm, and input voltage of 9.12 V. Under these conditions, the relationship between cadmium removal rate and time at different pH values ​​was explored. The experimental results are shown in Figure 2. Figure 31The experimental results show that the removal efficiency is the highest when the pH value is 4. This is because when the acidity of the solution is strong, the H + The content is high, the overpotential of hydrogen evolution caused by concentration polarization phenomenon is low, and the hydrogen evolution ability is strong. 2+ Therefore, the lower the pH value, the lower the removal rate of Cd. When the pH value is 5, although hydrogen precipitation and Cd 2+ The competitiveness of precipitation is weakened, but the degree of cadmium hydrolysis is increased, so the removal efficiency of cadmium is reduced.

[0142] Figure 31 Figure (c) investigates the relationship between Cd removal rate and time at different spacings between the ruthenium-iridium-titanium anode and the titanium cathode under experimental conditions of a solution concentration of 3 g / L and a pH of 4. The experimental results show that the optimal removal rate reached 77.2% when the spacing between the two electrode plates was 20 mm. This optimal spacing between the electrode plates resulted in a uniform electric field and high ion migration efficiency.

[0143] The comparison of the removal performance of other lead ions, copper ions, and cadmium ions with the present invention is shown in Table 1. It can be seen that the removal of lead ions by electrodeposition driven by the triboelectric nanogenerator of the present invention is comparable to existing traditional lead ion removal methods, such as chemical precipitation, adsorption, and biosorption. This comparison table proves that the use of triboelectric nanogenerators as a power source for lead ion removal is feasible and has application value in the removal of heavy metal ions. As a power source, triboelectric nanogenerators have the advantages of energy saving, environmental protection, high energy efficiency, and low cost. In addition, they can remove heavy metal ions by electrodeposition while collecting environmental energy. This method has broad application prospects and provides new ideas and methods for the removal of heavy metal ions.

[0144] Table 1 Comparison of other ion removal performances with the present invention

[0145]

[0146] Conclusion: This paper mainly starts from the PMM circuit and builds a heavy metal ion removal platform based on the friction nanogenerator. The PMM circuit combines the switching circuit and the maximum power tracking module to control the output circuit ripple to 0.01 V and the output voltage to 9.12 V. This voltage is sufficient to drive the removal of heavy metal ions. At the same time, the heavy metal ion removal platform is built to further 2+ , Pb 2+ and Cd 2+The results show that the removal effect of the three ions increases with the increase of reaction time. The experiment comprehensively considers the effects of the initial concentration of the solution, pH and electrode spacing on the experiment. The results show that under the optimal conditions, Cu 2+ The removal rate can reach up to 80%, Pb 2 + The removal rate can reach 86.90%, Cd 2+ The removal rate can reach 77.20%. This fully demonstrates the feasibility of triboelectric nanogenerators in the field of electrodeposition and provides new research ideas for future development.

Claims

1. A triboelectric nanogenerator for fluid energy harvesting, characterized in that: include: A base, a plurality of support plates, a stressed turbine blade, a rotating shaft, a contact and separation assembly, and a sliding friction assembly; The support plates are fixedly mounted on both sides of the base, and bearings are respectively embedded at the top ends of the support plates. The rotating shaft is rotatably connected to the support plates through the bearings. The forced turbine blades include a mounting portion and a plurality of blades, and the plurality of blades are fixedly connected to the outer periphery of the mounting portion. The forced turbine blades are fixedly mounted on one end of the rotating shaft through the mounting portion, and the contact and separation assembly and the sliding friction assembly are respectively mounted on the rotating shaft. The contact and separation assembly includes a rotor 1 inlaid with a plurality of universal balls, a balloon membrane, a fixed disc provided with a plurality of inlay holes, a plurality of copper electrodes coated with Ecoflex / ZnS films, a plurality of copper electrodes covered with sponge films, a gasket, a stator 1, a bracket 1, and a bracket 2. The gasket and the copper electrodes covered with sponge films are respectively fixedly connected to the stator 1, the thickness of the gasket is greater than the thickness of the copper electrodes covered with sponge films, the copper electrodes coated with Ecoflex / ZnS films are inlaid in the inlay holes of the fixed disc, the Ecoflex / ZnS films are close to the sponge films, the balloon membrane covers the surface of the fixed disc, and the universal balls are in close contact with the balloon membrane. The ZnS powder in the Ecoflex / ZnS film accounts for 3 to 13 wt% of the total mass of the ZnS powder and Ecoflex silica gel; The centers of the rotor 1, the balloon membrane, the fixed disc, and the stator 1 are provided with through holes. The rotating shaft passes through the through hole in the center of the rotor 1 and is fixedly connected to the rotor 1. The rotating shaft passes through the through holes in the center of the balloon membrane, the fixed disc, and the stator 1 in sequence. The apertures of the through holes of the balloon membrane, the fixed disc, and the stator 1 are larger than the diameter of the rotating shaft. The stator 1 is fixedly mounted on the bracket 1, the fixed disc is fixedly mounted on the bracket 2, and the brackets 1 and 2 are respectively fixedly mounted on the base. The sliding friction assembly includes a second rotor, a second stator, and a third bracket. The main bodies of the second rotor and the second stator are PCBs. Grid-shaped copper electrodes are evenly arranged on the second rotor and the second stator. A PTFE layer is attached to the copper electrode of the second rotor, and a GF film is attached to the copper electrode of the second stator. The PTFE layer and the GF film are in close contact. A through hole is provided at the center of the rotor 2 and the center of the stator 2. The rotating shaft passes through the through hole of the rotor 2 and is fixedly connected to the rotor 2. The rotating shaft passes through the through hole of the stator 2. The aperture of the through hole of the stator 2 is larger than the diameter of the rotating shaft. The stator 2 is fixedly mounted on the bracket 3, and the bracket 3 is fixedly mounted on the base.

2. The triboelectric nanogenerator for fluid energy harvesting according to claim 1, characterized in that: The shape of rotor 1 is a circle with a diameter of 200mm, with a 6mm through hole in the center, and the material is acrylic with a thickness of 12mm; the diameter of the universal ball is 18mm, and the material is bearing steel. The height of the universal ball protruding from rotor 1 is 5mm; the shape of the balloon membrane is a circle with a diameter of 200mm, with an 8mm through hole in the center, and the material is latex with a thickness of 0.04mm; the shape of the fixed disc is a circle with a diameter of 200mm, with an 8mm through hole in the center, and the material is acrylic with a thickness of 4mm. The shape of the inlay holes is a plurality of squares with a side length of 5cm; the shape of the copper electrode coated with Ecoflex / ZnS film is a plurality of squares with a side length of 5cm, wherein the thickness of the copper electrode layer is 0.065mm, and the thickness of Ecoflex / ZnS is 0.065mm. The thickness of the film is 0.1mm; the copper electrodes covered with sponge film are shaped like multiple squares with a side length of 5cm, wherein the thickness of the copper electrode layer is 0.065mm and the thickness of the sponge film is 0.5mm; the gasket is shaped like a long strip, made of acrylic, and has a thickness of 5mm; the shape of stator 1 is a circle with a diameter of 200mm, with an 8mm through hole in the center, made of acrylic, and has a thickness of 5mm; when the universal ball does not rotate into the inlay hole, the distance between the sponge film and the Ecoflex / ZnS film is 5mm, and the positions of the multiple copper electrodes coated with Ecoflex / ZnS film and the multiple copper electrodes covered with sponge film correspond one to one. When the universal ball rotates into the inlay hole, the positions of the multiple universal balls and the multiple inlay holes correspond one to one.

3. The triboelectric nanogenerator for fluid energy harvesting according to claim 1, characterized in that: The shape of rotor 2 is a circle with a diameter of 200 mm and a 6 mm through hole in the center. The copper electrode on rotor 2 is set as a ring with an outer diameter of 200 mm and an inner diameter of 70 mm with the center of rotor 2 as the center. The number of grids is 30 and evenly distributed; the shape of stator 2 is a square with a side length of 200 mm and an 8 mm through hole in the center. The copper electrode on the stator is set as a ring with an outer diameter of 200 mm and an inner diameter of 70 mm with the center of stator 2 as the center. The number of grids is 30 pairs and evenly distributed. One grid on each side of the copper electrode on the stator is extended as a terminal.

4. The triboelectric nanogenerator for fluid energy harvesting according to claim 1, characterized in that: The thickness of the PTFE layer is 0.01 mm, and the PTFE layer has the same shape as the rotor 2, and completely covers the rotor 2 when pasted; the thickness of the GF membrane is 0.15 mm, and the GF membrane has the same shape as the stator 2, and completely covers the stator 2 when pasted.

5. The triboelectric nanogenerator for fluid energy harvesting according to claim 1, characterized in that: The base, support plate, bracket one, bracket two and bracket three are all made of wood. The base is 35 cm long and 20 cm wide. The support plate is trapezoidal, with a lower base length of 14 cm, an upper base length of 5 cm and a height of 14 cm. Stator one is embedded in bracket one, and the fixed disc is embedded in bracket two. The height of bracket one and bracket two is 140 mm and the width is 200 mm. Stator two is embedded in bracket three. The height of bracket three is 140 mm and the width is 220 mm. The length of the rotating shaft is 305 mm and the diameter is 5 mm. It is made of carbon steel.

6. A method for preparing a triboelectric nanogenerator for fluid energy harvesting, characterized in that: The steps include: (1) Preparation of copper electrodes coated with Ecoflex / ZnS film: ZnS powder was added to Ecoflex silica gel and stirred to obtain a uniform mixture. The mixture was evenly coated on the surface of a wooden board on which a copper electrode had been pre-laid. The coated sample was transferred to a vacuum drying oven for curing to obtain a copper electrode coated with Ecoflex / ZnS film; (2) The product is obtained by installing the structure of the friction nanogenerator for fluid energy collection according to any one of claims 1 to 5.

7. The method for preparing a triboelectric nanogenerator for fluid energy harvesting according to claim 6, characterized in that: In step (1), the coating thickness is 0.1 mm, the curing temperature is 60° C., and the curing time is 4 h.

8. The method for preparing a triboelectric nanogenerator for fluid energy harvesting according to claim 6, characterized in that: In step (1), the obtained mixture is evenly coated on the surface of the wooden board on which the copper electrodes have been pre-laid by spin coating at a rotation speed of 1000 r / min.

9. Use of the fluid energy harvesting triboelectric nanogenerator according to any one of claims 1 to 5 in the removal of heavy metal ions.

10. The application of a triboelectric nanogenerator for fluid energy harvesting in heavy metal ion removal according to claim 9, characterized in that: Using triboelectric nanogenerators for fluid energy harvesting to construct an electrodeposition system for Cu removal 2+ , Pb 2+ and Cd 2+ .

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