Graphene oxide interlayer confined piezoelectric modulation composite film and electric field driven preparation method and application thereof

Abstract

This invention discloses an interlayer confined piezoelectric composite film of graphene oxide, its electric field-driven preparation method, and its application. The preparation method includes: preparing a graphene oxide dispersion using the Hummers method and filtering it to form a graphene oxide film; placing the graphene oxide film in an electric-driven device, introducing different precursor solutions on both sides of the film, and driving the precursor components to migrate into the interlayer confined space of the graphene oxide under the action of an applied electric field; under the synergistic effect of electric field driving and interlayer confinement, the precursors entering the interlayer react and crystallize in situ to form a piezoelectric functional phase. The prepared composite film can generate piezoelectric polarization under mechanical stimulation conditions and can be used for ion selective adsorption / separation, especially suitable for the selective adsorption / separation of uranium and vanadium ions in high-salt water systems. This invention achieves a synergistic improvement in interfacial charge regulation and ion selectivity regulation by constructing a piezoelectric functional phase in situ within the interlayer confined space of graphene oxide.

Description

Technical Field

[0001] This invention belongs to the field of separation membrane materials, functional composite membranes and ion selective separation technology, specifically relating to an interlayer confined piezoelectric modulated composite membrane of graphene oxide, an electric field driven preparation method and its application in ion selective adsorption and / or separation. Background Technology

[0002] With the increasing demand for nuclear energy, new energy storage, industrial wastewater treatment, and strategic resource recovery, the efficient and selective separation of metal species in complex aquatic systems has become an important research direction in separation science, membrane technology, and resource utilization. Uranium is a crucial strategic element supporting the nuclear fuel cycle and the long-term development of nuclear energy, while vanadium, due to its application in vanadium redox flow batteries and high-performance alloys, has become an important metal resource in new energy storage and high-end manufacturing. In uranium-vanadium co-occurring mineral leaching solutions, uranium-containing high-salt waste liquids, seawater, and other complex saline systems, uranium and vanadium often coexist, and both typically exhibit strong oxygen-loving coordination characteristics. Their existence form, interfacial binding behavior, and migration behavior in aqueous solutions are easily affected by pH, carbonate complexation, ionic strength, and coexisting ions, readily competing for oxygen-containing coordination sites at the solid-liquid interface. This makes uranium / vanadium separation a typical challenge in the selective separation of similar metal species.

[0003] Currently, uranium / vanadium separation mainly relies on methods such as solvent extraction, ion exchange, membrane separation, and adsorption. Among these, membrane separation and adsorption separation have attracted widespread attention in the ion separation of complex aqueous systems due to their advantages such as low energy consumption, relatively simple operation, and designable material structures. For adsorption or membrane adsorption materials, the separation selectivity is usually determined by both interfacial chemistry and pore structure. Surface charge, functional groups, and coordination sites affect the binding, coordination, and reaction behavior of metal species at the interface, while pore size distribution, specific surface area, pore connectivity, and mass transfer pathways affect the accessibility of active sites and ion transport efficiency. However, traditional adsorption materials and conventional three-dimensional porous materials often rely on pre-set coordination sites, fixed pore structures, and static interfacial chemistry to achieve separation, which usually suffers from problems such as tortuous pores, uneven connectivity, insufficient utilization of effective sites, and difficulty in controlling the local reaction environment. For metal species with similar or competing properties, such as uranium and vanadium, relying solely on the above static separation mechanisms is usually insufficient to achieve ideal selective separation results.

[0004] Compared to conventional three-dimensional porous materials, two-dimensional interlayer channels possess shorter mass transfer paths, more sufficient interfacial contact, and tunable nanoscale space, which are beneficial for reducing mass transfer resistance and providing a confined environment for ion transport, interfacial coordination, and charge modulation. Graphene oxide films are a representative type of two-dimensional layered separation material. Graphene oxide nanosheets can form sub-nanometer to nanoscale interlayer channels through layer stacking. Their tunable interlayer spacing, abundant oxygen-containing functional groups, and carbon framework capable of participating in charge transport provide a structural basis for ion transport, interfacial coordination, and charge modulation. Furthermore, the interlayer space of graphene oxide can also serve as a nanoscale confined reaction field. Its oxygen-containing functional groups can provide interfacial interaction sites for the intercalation, anchoring, or in-situ growth of functional components, thereby enabling the adjustment of channel size, interfacial charge, and local reaction environment.

[0005] However, most existing graphene oxide-based adsorption or separation materials still primarily rely on pre-constructed interlayer structures, fixed interlayer spacing, and inherent oxygen-containing functional groups for ion recognition, with separation mechanisms mainly based on size sieving and static adsorption. In practical applications, graphene oxide interlayer channels typically lack active regulation capabilities, making it difficult to dynamically adjust channel size, interfacial charge distribution, local reaction environment, and ion migration behavior under external stimuli. Therefore, existing graphene oxide membranes still suffer from limited selective separation capabilities and insufficient interfacial regulation in complex water systems.

[0006] To enhance the ability of graphene oxide films to regulate ion transport and interfacial reaction behavior, functional materials with external field response characteristics have attracted attention. Among them, piezoelectric materials can generate polarization charges and local electric fields under mechanical stimulation, thereby regulating the charge state and local reaction environment at the solid-liquid interface, and have potential application value in ion migration regulation, interfacial charge regulation, and enhancement of liquid-phase interfacial reactions. Mechanical stimulation, especially ultrasonic stimulation, is easy to transmit in the liquid phase, has a rapid response, and can be dynamically adjusted, making it suitable for driving solid-liquid interfacial processes. However, existing piezoelectric materials are mostly used in the form of powders, particles, surface loading, or simple physical composites, which usually suffer from problems such as uneven piezoelectric phase distribution, weak interfacial bonding, easy agglomeration, and difficulty in forming continuous spatial coupling and charge transport coupling with ion adsorption / coordination interfaces. Especially in two-dimensional layered film systems such as graphene oxide, how to construct a spatially continuous, interfacially coupled, and mechanically responsive piezoelectric functional phase in situ within the interlayer channels, and how to enable piezoelectric polarization, charge transport, and ion adsorption / coordination processes to occur synergistically on the same nano-confined solid-liquid interface, remains an unsolved problem in the existing technology.

[0007] Therefore, it is still necessary to develop a piezoelectrically controlled composite membrane confined within graphene oxide layers and its preparation method, so that the piezoelectric functional phase can be stably constructed within the interlayer channels of graphene oxide and effectively coupled with the graphene oxide interface. This allows for dynamic regulation of the interfacial charge, local reaction environment, and ion adsorption / separation behavior under mechanical stimulation, thereby improving its ion selective adsorption and / or separation performance in complex water systems, especially in systems containing similar metal species such as uranium and vanadium. Summary of the Invention

[0008] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0009] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0010] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a graphene oxide interlayer confined piezoelectric modulated composite film.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a graphene oxide interlayer confined piezoelectric modulated composite film, characterized in that: the composite film uses a layered graphene oxide film as the structural matrix, and a piezoelectric functional phase is formed in situ crystallized in the interlayer confined space to form a piezoelectric functional phase, wherein the piezoelectric functional phase is distributed in the interlayer of graphene oxide. The piezoelectric functional phase is selected from at least one of barium titanate, barium strontium titanate, sodium bismuth titanate, sodium potassium niobate, lead titanate, lead zirconate titanate, lead magnesium niobate-lead titanate, or bismuth ferrite.

[0012] As a preferred embodiment of the interlayer confined piezoelectric modulated composite film of graphene oxide described in this invention, the piezoelectric functional phase has a nanoscale sheet structure and is continuously or quasi-continuously distributed along the graphene oxide layer direction.

[0013] As a preferred embodiment of the graphene oxide interlayer confined piezoelectric modulated composite film of the present invention, wherein: the piezoelectric functional phase and the graphene oxide are connected by chemical bonds to form an interfacial bonding structure, and the composite film can generate piezoelectric polarization under mechanical stimulation conditions.

[0014] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an interlayer confined piezoelectric modulated composite film of graphene oxide, characterized by comprising: Graphene oxide dispersion was prepared using the Hummers method. After ultrasonic dispersion, the graphene oxide dispersion is filtered under negative pressure to form a graphene oxide membrane with a layered stacked structure, and then dried for later use. The graphene oxide film was placed in an electric drive device, and different precursor solutions were introduced on both sides of the film. Under the action of an external electric field, the precursor components were driven to migrate into the confined space between the graphene oxide layers. Under the combined effect of electric field driving and interlayer confinement, the precursors that migrate into the interlayer undergo a first-step electro-driven reaction and a second-step electro-driven reaction in sequence. The first-step electro-driven reaction forms an initial intermediate, and the second-step electro-driven reaction crystallizes in situ on the basis of the intermediate to form a piezoelectric functional phase.

[0015] In a preferred embodiment of the preparation method described in this invention, the applied voltage is 1~6 V and the reaction time is 3~6 h.

[0016] In a preferred embodiment of the preparation method described in this invention, the graphene oxide membrane is formed by negative pressure filtration, the filtration pressure is 0.08 MPa, and the direction of the applied electric field is perpendicular to the direction of the graphene oxide membrane layer.

[0017] In a preferred embodiment of the preparation method described in this invention, the precursor includes a metal source and a precursor whose chemical composition matches that of the piezoelectric functional phase; in the first electro-drive reaction, 50-70 mL of an aqueous solution of the metal source is added to the anode side, and 50-70 mL of an aqueous solution of NaOH is added to the cathode side; in the second electro-drive reaction, 50-70 mL of an ethanol solution of the precursor is introduced to the anode side, and 50-70 mL of an ethanol solution of NaOH is introduced to the cathode side; wherein the metal source is selected from at least one of barium source, sodium source, lead source, and bismuth source, and the precursor is selected from at least one of titanium precursor, niobium precursor, zirconium precursor, and iron precursor.

[0018] In a preferred embodiment of the preparation method described in this invention, the concentration of the metal ion aqueous solution is 0.1 mol / L; the concentration of the NaOH aqueous solution is 0.15~0.40 mol / L; the concentration of the precursor ethanol solution is 0.05~0.20 mol / L; and the concentration of the NaOH ethanol solution is 0.15~0.40 mol / L.

[0019] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of graphene oxide interlayer confined piezoelectric modulated composite membrane in ion selective adsorption and / or separation.

[0020] In a preferred embodiment of the application described in this invention, the application is to achieve selective separation / adsorption of uranium and vanadium ions in a high-salt water system; the graphene oxide interlayer confined piezoelectric modulated composite film generates piezoelectric polarization under mechanical stimulation to achieve selective separation / adsorption of uranium and vanadium, wherein the mechanical stimulation is ultrasound.

[0021] In a preferred embodiment of the application described in this invention, the application is to selectively adsorb and / or separate vanadium species in a high-salt water system containing both uranium and vanadium; the interlayer confined piezoelectric modulated composite membrane of graphene oxide generates piezoelectric polarization and interfacial charge regulation under mechanical stimulation, promoting the selective adsorption, coordination fixation, and / or oxidation reaction of vanadium species at the composite membrane interface, while inhibiting the competitive adsorption of uranium species; the mechanical stimulation is ultrasound.

[0022] Beneficial effects of this invention: (1) The present invention constructs a piezoelectric functional phase in situ between graphene oxide layers through the synergistic effect of electric field driving and interlayer confinement, avoiding the problems of easy aggregation, uneven distribution and weak interfacial bonding of piezoelectric components in traditional physical mixing or surface loading methods. (2) The piezoelectric functional phase formed by the present invention can be continuously or quasi-continuously distributed between graphene oxide layers and form a stable interface bonding structure with the film substrate, which is beneficial to construct a continuous piezoelectric control interface in the confined interlayer channel and improve the external field response and interface charge transport efficiency. (3) The composite membrane of the present invention can generate piezoelectric polarization under mechanical stimulation, thereby regulating the local charge distribution, interfacial reaction environment and ion migration behavior, and enhancing the selective separation ability of target ions in complex water systems. (4) The composite membrane and its preparation method provided by the present invention are suitable for ion selective adsorption / separation, especially suitable for systems containing similar metal species such as uranium and vanadium. It can be used to achieve selective separation of uranium / vanadium species, selective removal of vanadium species or front-end purification of uranium recovery, and has good application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a flowchart illustrating the preparation process of the graphene oxide interlayer confined piezoelectric modulated composite film of the present invention.

[0024] Figure 2 The images show the XRD patterns of the membrane materials obtained in Example 1, Comparative Example 1, and Comparative Example 2, and the TEM image of Example 1.

[0025] Figure 3 The images shown are cross-sectional SEM images of the membrane materials obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0026] Figure 4 The image shows a TEM image of the membrane material in Example 1 and its corresponding elemental distribution diagram.

[0027] Figure 5 The images show the AFM diagrams and cross-sectional height diagrams of the membrane materials obtained in Example 1 and Comparative Example 2.

[0028] Figure 6 XPS images of the membrane materials obtained in Example 1 and Comparative Example 1.

[0029] Figure 7 The image shows the piezoelectric response of the composite membrane obtained in Example 1.

[0030] Figure 8 This is a comparison chart of the V / U separation performance of Example 1, Comparative Example 1, and Comparative Example 2.

[0031] Figure 9 The diagram shows the V / U separation performance of Example 1 under different pH and ultrasonic power.

[0032] Figure 10 The images show the XRD patterns of the membrane materials obtained in Example 1 and Comparative Example 3.

[0033] Figure 11 The images show the XRD patterns of the membrane materials obtained in Example 1 and Comparative Example 4.

[0034] Figure 12 The images show the XRD patterns of the membrane materials obtained in Example 1 and Comparative Example 5. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0038] The raw materials used in the embodiments of the present invention are shown in Table 1.

[0039] Table 1

[0040] The solutions used in the embodiments of this invention: Dissolve NaOH in anhydrous ethanol to prepare a 0.21 mol / L NaOH ethanol solution; TiCl4 was dissolved in anhydrous ethanol at low temperature (0-4 °C) to prepare a 0.1 mol / L TiCl4 ethanol solution.

[0041] The instruments used in the embodiments of this invention are shown in Table 2.

[0042] Table 2

[0043] The performance testing method in this embodiment of the invention includes: (1) Adsorption kinetics test: Prepare UO2 at the same concentration of 50 ppm 2+ With VO 2+ Mixed solutions were used to evaluate the effect of GO@BaTiO3 on VO 2+ The adsorption performance was determined. Specific procedures included adding 10 mg GO@BaTiO3 to a 10 mL solution. The adsorption experiment was conducted at 4 °C. Solution samples were collected and filtered at time points of 1 min, 2 min, 5 min, 10 min, 20 min, 40 min, 1 h, 2 h, and 3 h. The concentrations of uranium and vanadium in the filtrate were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The adsorption data were fitted to pseudo-first-order and pseudo-second-order kinetic models according to equations (4) and (3), respectively.

[0044] Where t (min) represents the contact time, Q t (mg g -1 ) and Q e (mg g -1 ) represent the adsorption amounts of uranium and vanadium at time t, respectively, while k2 (min·g·mg) -1 ) is the pseudo-second-order adsorption rate constant. After formula conversion, t / Q tThe plot is drawn with t as the vertical axis and t as the horizontal axis. The separation factor data are calculated according to equation (5).

[0045] Q e1 (mg·g -1 ) and Q e2 (mg·g -1 ) represent the equilibrium adsorption capacities corresponding to V and U, respectively.

[0046] (2) Adsorption isotherm measurement: Adsorption isotherms were determined by evaluating the adsorption capacity of GO@BaTiO3 for V and U, with an initial solution concentration range of 10-100 ppm. In the adsorption experiment, 10 mg of GO@BaTiO3 was added to 10 mL of aqueous solution. After adsorption equilibrium was reached, the suspension was filtered, and the residual concentrations of V and U in the filtrate were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Subsequently, the obtained adsorption isotherm data were fitted using the Langmuir model and the Freundlich model, respectively, according to equations (6) and (7).

[0047] in C e (mg L -1 ) indicates VO 2+ / UO2 2+ The mass concentration at equilibrium adsorption. Q e (mg g -1 The value represents the adsorption amount at equilibrium V / U. Q m (mg g -1 The ) represents the theoretical maximum adsorption capacity of vanadium. K L (L mg -1 ) represents the Langmuir constant; K F (mg g -1 ) represents the Freundlich constant.

[0048] Example 1 This embodiment provides a method for preparing a graphene oxide interlayer confined piezoelectric modulated composite film, such as... Figure 1 As shown, the specific steps include: (1) Graphene oxide dispersion was prepared using the Hummers method. 1.71 mL of the graphene oxide dispersion was added to 8.29 mL of deionized water and ultrasonically dispersed at 720 W for 15 min. Using a nylon membrane with a diameter of 50 mm and a pore size of 0.22 μm as a substrate, the resulting dispersion was filtered under negative pressure at 0.08 MPa to form a membrane, which was then dried at room temperature to obtain a layered graphene oxide membrane.

[0049] (2) The graphene oxide film is placed in an electric drive device, and the direction of the applied electric field is perpendicular to the direction of the graphene oxide film layer to sequentially carry out the first step of the electric drive reaction and the second step of the electric drive reaction: The first step of the electro-driven reaction: 70 mL of 0.1 mol / L Ba(NO3)2 aqueous solution was added to the anode side, and 70 mL of 0.4 mol / L NaOH aqueous solution was added to the cathode side. A DC voltage of 3 V was applied, and the reaction was carried out at room temperature for 3 h.

[0050] After the reaction was complete, the solutions on both sides were poured off, and the membrane surface was rinsed with deionized water.

[0051] The second step of the electro-driven reaction: After the first step of the reaction was completed, 70 mL of TiCl4 ethanol solution was added to the anode side and 70 mL of NaOH ethanol solution was added to the cathode side. The reaction was continued for 3 h under a DC voltage of 3 V.

[0052] After the reaction was completed, the solution was poured off, the membrane surface was rinsed with deionized water, and then immersed in deionized water for 12 h. Subsequently, it was dried at room temperature to obtain the interlayer confined piezoelectric modulated composite membrane.

[0053] In the above process, the barium source preferentially forms a BaCO3 intermediate in the interlayer of graphene oxide, which then reacts further with titanium-containing species formed from the titanium precursor, and crystallizes in situ to form a perovskite-structured piezoelectric functional phase. The resulting piezoelectric functional phase is BaTiO3, and it is distributed continuously or quasi-continuously in the interlayer of graphene oxide.

[0054] Comparative Example 1 The difference between this comparative example and Example 1 is that only step (1) is used, and step (2) is omitted to obtain a pure graphene oxide film.

[0055] Comparative Example 2 This comparative example provides a method for preparing a physically mixed BaTiO3 / graphene oxide composite film, specifically including the following steps: (1) Weigh 0.5 mg of BaTiO3 powder synthesized by solid-phase method, add it to deionized water, and sonicate it at 650 W for 15 min to obtain a uniformly dispersed BaTiO3 dispersion. Add 1.71 mL of graphene oxide dispersion with a mass concentration of 7.24 g / L to the BaTiO3 dispersion, and add deionized water to make up to 10 mL. Sonicate it at 720 W for 15 min to fully mix BaTiO3 and graphene oxide to obtain a physically mixed composite dispersion.

[0056] (2) The obtained composite dispersion was placed in a vacuum filtration device and filtered to form a membrane at 0.08 MPa. The substrate used was a nylon membrane with a diameter of 50 mm and a pore size of 0.22 μm. After filtration, the obtained membrane material was naturally dried at room temperature to obtain a physically mixed BaTiO3 / graphene oxide composite membrane.

[0057] Example 2 This embodiment analyzes the structure, morphology, and piezoelectric properties of the film materials obtained in Example 1, Comparative Example 1, and Comparative Example 2. Specifically: Figure 2 The XRD patterns of Example 1, Comparative Examples 1 and 2, and the TEM image of Example 1 are shown. Example 1 shows obvious characteristic peaks of tetragonal BaTiO3, and the (002) peak of graphene oxide undergoes a low-angle shift and broadens, directly proving that BaTiO3 successfully entered the interlayer and expanded the interlayer spacing. The lattice fringes in the TEM image further confirm the crystallinity of BaTiO3.

[0058] Figure 3 The SEM cross-sectional images visually demonstrate the structural differences among the three films. Example 1 shows a smooth morphology with a layered structure, while Comparative Example 2 (physical mixing) exhibits a rough, aggregated morphology. This confirms that the electric field-driven in-situ crystallization strategy can effectively prevent the aggregation of nanoparticles.

[0059] Figure 4 The TEM elemental distribution map shows that Ba, Ti, O and C elements are uniformly distributed in the material, which further confirms that the piezoelectric functional phase is uniformly loaded between the graphene oxide layers, rather than locally stacked.

[0060] Figure 5 and Figure 6 XPS spectra were provided. The presence of Ti-O and Ba-O bonds confirms the formation of BaTiO3. The change in the CO peak may indicate the formation of chemical bonds between graphene oxide and BaTiO3, which explains why Example 1 exhibits a stable interfacial bonding structure. Specifically, Ti-OC bond signals were also observed in the Ti 2p high-resolution spectrum, directly confirming the formation of chemical bonds.

[0061] In summary, the X-ray diffraction results show that Comparative Example 1 does not contain the BaTiO3 crystalline phase, Comparative Example 2 exhibits the diffraction characteristics of BaTiO3 powder particles, while Example 1 shows the characteristic peaks of tetragonal BaTiO3. At the same time, the (002) diffraction peak of graphene oxide undergoes a low-angle shift and broadens, indicating that BaTiO3 is formed in the confined space between graphene oxide layers.

[0062] Microscopic morphology results show that Comparative Example 1 has only a layered graphene oxide structure, BaTiO3 in Comparative Example 2 is mainly dispersed in the form of particles and has local aggregation, while BaTiO3 in Example 1 is distributed in nanosheets continuously or quasi-continuously between the graphene oxide layers.

[0063] Piezoelectric response test, such as Figure 7 As shown, the results indicate that Example 1 exhibits obvious polarization reversal behavior and butterfly amplitude response, demonstrating that the formed piezoelectric functional phase has good switchable polarization characteristics and piezoelectric activity.

[0064] The interlayer confined piezoelectric modulated composite membrane prepared in Example 1, the pure graphene oxide membrane prepared in Comparative Example 1, and the physically mixed BaTiO3 / graphene oxide composite membrane prepared in Comparative Example 2 were used to test the ion selective adsorption and / or separation performance in a mixed water system containing uranium and vanadium. The results are as follows: Figure 8 , 9 As shown.

[0065] The results showed that, under ultrasonic mechanical stimulation, the composite membrane obtained in Example 1 exhibited better selectivity at pH 3 and had an ultrasonic power window that was conducive to the selective adsorption of vanadium ions; in contrast, the selectivity regulation ability of Comparative Examples 1 and 2 was significantly weaker.

[0066] In a spiked real seawater system, the composite membrane obtained in Example 1 showed an adsorption capacity of 71.43 mg / g for vanadium ions and 4.83 mg / g for uranium ions, with a separation factor of 69.03, which was significantly better than that of Comparative Example 1 and Comparative Example 2.

[0067] Comparative Example 3 The difference between this comparative example and Example 1 is that the DC voltage in step (2) is replaced with 0, 2, and 6V respectively, while the other steps are the same as in Example 1, and the graphene oxide interlayer confined piezoelectric modulated composite film is obtained.

[0068] Figure 10 The XRD patterns of Example 1 and Comparative Example 3 are shown, and it can be seen that the DC voltage for synthesizing BaTiO3 is preferably 2V and 3V.

[0069] Comparative Example 4 The difference between this comparative example and Example 1 is that the concentration of the NaOH ethanol solution in step (2) is replaced with 0.04, 0.18, and 0.40 mol·L⁻¹, respectively. -1 The remaining steps are the same as in Example 1, and a graphene oxide interlayer confined piezoelectric modulated composite film is obtained.

[0070] Figure 11 The XRD patterns of Example 1 and Comparative Example 4 are shown. It can be seen that the optimal concentrations of the NaOH ethanol solution for synthesizing BaTiO3 are 0.18 and 0.21 mol·L⁻¹, respectively. -1 .

[0071] Comparative Example 5 The difference between this comparative example and Example 1 is that the concentration of the TiCl4 ethanol solution in step (2) is replaced with 0.07, 0.08, and 0.20 mol·L⁻¹, respectively. -1 The remaining steps are the same as in Example 1, and a graphene oxide interlayer confined piezoelectric modulated composite film is obtained.

[0072] Figure 12 The XRD patterns of Example 1 and Comparative Example 5 are shown. It can be seen that the optimal concentrations of the TiCl4 ethanol solution for synthesizing BaTiO3 are 0.08 and 0.10 mol·L⁻¹, respectively. -1 .

[0073] In summary, to address the limitations of existing graphene oxide membranes in their ability to selectively regulate ions in complex water systems, as well as the weak interfacial bonding between piezoelectric functional materials and the membrane substrate, making it difficult to form a continuous controllable interface, this invention provides an interlayer confined piezoelectric controllable composite membrane of graphene oxide, its electric field-driven preparation method, and its application. This enhances the membrane material's ability to control ion transport, interfacial charge distribution, and interfacial reaction behavior, thereby improving its selective adsorption / separation performance in complex water systems.

[0074] The interlayer confined piezoelectric modulated composite film provided by this invention uses a layered graphene oxide film as the structural matrix, in-situ crystallizing a piezoelectric functional phase within the confined space between its layers. This piezoelectric functional phase is distributed between the graphene oxide layers. The piezoelectric functional phase is at least one of barium titanate, barium strontium titanate, sodium bismuth titanate, sodium potassium niobate, lead titanate, lead zirconate titanate, lead magnesium niobate-lead titanate, or bismuth ferrite, preferably BaTiO3. The piezoelectric functional phase exhibits a nanoscale sheet-like structure and is continuously or quasi-continuously distributed along the graphene oxide layers. The piezoelectric functional phase and graphene oxide are chemically bonded to form an interfacial bonding structure, enabling the composite film to generate piezoelectric polarization under mechanical stimulation.

[0075] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. An interlayer confined piezoelectrically regulated graphene oxide composite film, characterized in that: The composite film uses a layered graphene oxide film as the structural matrix, and a piezoelectric functional phase is formed by in-situ crystallization in the confined space between its layers. The piezoelectric functional phase is distributed between the graphene oxide layers. The piezoelectric functional phase is selected from at least one of barium titanate, barium strontium titanate, sodium bismuth titanate, sodium potassium niobate, lead titanate, lead zirconate titanate, lead magnesium niobate-lead titanate, or bismuth ferrite.

2. The graphene oxide interlayer confined piezoelectric modulated composite film according to claim 1, wherein: The piezoelectric functional phase has a nanoscale sheet structure and is continuously or quasi-continuously distributed along the graphene oxide layer.

3. The graphene oxide interlayer confined piezoelectric regulated composite film according to claim 1, wherein: The piezoelectric functional phase and graphene oxide are connected by chemical bonds to form an interfacial bonding structure, and the composite film can generate piezoelectric polarization under mechanical stimulation.

4. The method for preparing the graphene oxide interlayer confined piezoelectric modulated composite film according to any one of claims 1-3, characterized in that: include, Graphene oxide dispersion was prepared using the Hummers method. After ultrasonic dispersion, the graphene oxide dispersion is filtered under negative pressure to form a graphene oxide membrane with a layered stacked structure, and then dried for later use. The graphene oxide film was placed in an electric drive device, and different precursor solutions were introduced on both sides of the film. Under the action of an external electric field, the precursor components were driven to migrate into the confined space between the graphene oxide layers. Under the combined effect of electric field driving and interlayer confinement, the precursors that migrate into the interlayer undergo a first-step electro-driven reaction and a second-step electro-driven reaction in sequence. The first-step electro-driven reaction forms an initial intermediate, and the second-step electro-driven reaction crystallizes in situ on the basis of the intermediate to form a piezoelectric functional phase.

5. The production method according to claim 4, characterized by: The applied voltage is 1~6 V, and the reaction time is 3~6 h.

6. The production method according to claim 4, characterized by: The graphene oxide membrane is formed by negative pressure filtration, with a filtration pressure of 0.08 MPa and the applied electric field direction perpendicular to the graphene oxide membrane surface direction.

7. The production method according to claim 4, wherein: The precursor includes a metal source and a precursor whose chemical composition matches that of the piezoelectric functional phase; in the first electro-drive reaction, 50-70 mL of an aqueous solution of the metal source is added to the anode side and 50-70 mL of an aqueous solution of NaOH is added to the cathode side; in the second electro-drive reaction, 50-70 mL of an ethanol solution of the precursor is introduced to the anode side and 50-70 mL of an ethanol solution of NaOH is introduced to the cathode side; wherein, the metal source is selected from at least one of barium source, sodium source, lead source, and bismuth source, and the precursor is selected from at least one of titanium precursor, niobium precursor, zirconium precursor, and iron precursor.

8. The production method according to claim 7, characterized by: The concentration of the metal ion aqueous solution is 0.1 mol / L; the concentration of the NaOH aqueous solution is 0.15~0.40 mol / L; the concentration of the precursor ethanol solution is 0.05~0.20 mol / L; and the concentration of the NaOH ethanol solution is 0.15~0.40 mol / L.

9. Use of the graphene oxide interlayer confined piezoelectric modulated composite film according to any one of claims 1 to 3 for ion selective adsorption and / or separation, characterized in that: The application is to achieve selective separation / adsorption of uranium and vanadium ions in a high-salt water system; the graphene oxide interlayer confined piezoelectric modulated composite film generates piezoelectric polarization under mechanical stimulation to achieve selective separation / adsorption of uranium and vanadium, wherein the mechanical stimulation is ultrasound.

10. Use according to claim 9, wherein: The application is to selectively adsorb and / or separate vanadium species in a high-salt water system containing both uranium and vanadium; the graphene oxide interlayer confined piezoelectric modulated composite film generates piezoelectric polarization and interfacial charge regulation under mechanical stimulation, promoting the selective adsorption, coordination fixation and / or oxidation reaction of vanadium species at the composite film interface, while inhibiting the competitive adsorption of uranium species; the mechanical stimulation is ultrasound.

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