Defect WO for seawater photoelectric detection 3-x Ferroelectric Ba 1-x Pr x TiO3 composite nanocrystal, preparation method and application thereof

Abstract

This invention provides a defect WO for seawater photoelectric detection 3‑x @FerroelectricBa 1‑x Pr x TiO3 composite nanocrystals, their preparation methods and applications, with Pr as the main component. 3+ Doped Ba 1‑ x Pr x Using TiO3 ferroelectric material as the core, WO3 with oxygen vacancy defects is grown in situ on the surface of the core. 3‑x Nanocrystals, the core and surface in situ grown WO4 3‑x The nanocrystals form a heterojunction structure, which improves the separation efficiency of photogenerated carriers, the light absorption range, and corrosion resistance. The prepared composite nanocrystals can be used to construct photoelectrodes, exhibiting high sensitivity, fast response, and good stability in seawater environments, and have promising applications in marine environmental monitoring and other fields.

Description

Technical Field

[0001] This invention relates to the fields of optoelectronic functional materials and optoelectronic detection technology, and specifically to a defect WO for seawater optoelectronic detection. 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals, their preparation methods, and applications, specifically involving a WO3 nanocrystal with oxygen vacancy defects. 3-x With Pr 3+ Nanocrystals of barium titanate ferroelectric composites, their preparation methods, and their application in seawater photoelectric detection. Background Technology

[0002] Seawater photoelectric detection is in high demand in fields such as marine environmental monitoring, underwater communication, marine resource exploration, and national defense security. However, the high salinity, corrosiveness, and complex composition of the seawater environment pose severe challenges to the stability, photoresponse performance, and anti-interference capabilities of photoelectric detection materials. Traditional photoelectric detection materials (such as Si and TiO2) face many bottlenecks in seawater environments: on the one hand, the high salinity and strong corrosiveness of seawater cause corrosion and dissolution of the material surface, destroying its microstructure; on the other hand, traditional materials have narrow spectral absorption ranges, photogenerated charge carriers are prone to recombination, resulting in low photoelectric conversion efficiency, and their performance is prone to degradation under long-term seawater immersion and light exposure, failing to meet the requirements for long-term stable detection.

[0003] To address these issues, researchers have attempted to optimize material properties through composite modification and doping. BaTiO3, a ferroelectric material, exhibits excellent ferroelectric, dielectric, and photoelectric properties, demonstrating promising application potential in photodetection. The spontaneous polarization of BaTiO3 generates a strong built-in electric field, effectively driving the separation of photogenerated carriers and suppressing their recombination, thereby improving photoresponse. Rare-earth doping (such as Pr...) can further enhance this effect. 3+ (etc.) can adjust the crystal phase structure and ferroelectric properties of BaTiO3; oxygen vacancy defects (WO3) can be introduced into metal oxides (such as WO3). 3-x Ferroelectric materials can have their band structure adjusted to enhance visible light absorption and provide abundant active sites for catalytic reactions. If the polarization field effect of ferroelectric materials can be combined with the broad-spectrum absorption characteristics of defective semiconductors to construct a tight heterojunction, high-performance seawater-stabilized optoelectronic materials are expected to be obtained. However, in existing technologies, combining Pr-doped BaTiO3 ferroelectrics with defective WO3... 3-xA method for optimizing seawater photoelectric detection performance through in-situ nanocrystalline composites and synergistic regulation of oxygen vacancy concentration using a simplified process has not yet been reported. Existing composite systems often suffer from weak interfacial bonding and insufficient synergistic effects of ferroelectric polarization and defect regulation, failing to effectively address the key technical challenges of low performance and poor long-term stability of photoelectric detection materials in seawater environments. Therefore, developing a composite photoelectric detection material that combines broad-spectrum absorption, efficient charge separation capabilities, and excellent seawater stability has significant practical implications and application value. Summary of the Invention

[0004] In view of this, the present invention proposes a defect WO for seawater photoelectric detection. 3-x @FerroelectricBa 1-x Pr x This paper proposes a method for preparing TiO3 composite nanocrystals and their applications to address the problems existing in the prior art.

[0005] To achieve the above objectives, this invention proposes a defect WO for seawater photoelectric detection. 3-x @FerroelectricBa 1- x Pr x TiO3 composite nanocrystals include: With Pr 3+ Doped Ba 1-x Pr x Using TiO3 ferroelectric material as the core, WO3 with oxygen vacancy defects is grown in situ on the surface of the core. 3-x Nanocrystals, the core and surface in situ grown WO4 3-x Nanocrystals form heterojunction structures.

[0006] Optionally, the WO 3-x Oxygen vacancy defects in nanocrystals are introduced during high-temperature crystallization, which are introduced by the reducing atmosphere generated by polymer carbonization and the decomposition of WCl6 during high-temperature crystallization; the concentration of oxygen vacancy defects is adjusted by the temperature and holding time during high-temperature crystallization.

[0007] On the other hand, the present invention provides defect WO 3-x @FerroelectricBa 1-x Pr x Methods for preparing TiO3 composite nanocrystals include: Ba(OH)2·H2O and Pr(NO3)3·6H2O were dissolved in glacial acetic acid. After stirring and dissolving, polyvinylpyrrolidone, tetrabutyl titanate, N,N-dimethylformamide and anhydrous ethanol were added to the solution in sequence and stirred to form a precursor sol. The precursor sol was spin-coated onto conductive glass to form Ba on the conductive glass. 1-x Prx TiO3 precursor thin film; Dissolve WCl6 in ethanol and stir to form a first solution. Add the first solution dropwise to Ba. 1-x Pr x The surface of the TiO3 precursor film was spin-coated to achieve uniform coverage, thus obtaining a composite film. The composite film is placed in a tube furnace and subjected to high-temperature crystallization under an air atmosphere. The heat treatment includes uniform heating and holding at the crystallization temperature. The WO3 content is adjusted by controlling the crystallization temperature and the holding time. 3-x The oxygen vacancy content in the sample, after cooling, yields defective WO3. 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals.

[0008] Optionally, the Ba(OH)₂·H₂O, Pr(NO₃)₃·6H₂O and C 16 H 36 In the O4Ti dosage, the molar ratio of Ba:Pr:Ti is (1-x):x:1, where the value of x ranges from 0 to 0.15.

[0009] Optionally, the amount of WCl6 used may be such that the final WO3 is... 3-x with Ba 1-x Pr x The molar ratio of TiO3 is controlled between 0.3 and 3.0:1.0.

[0010] Optionally, the conductive glass is FTO conductive glass.

[0011] Optionally, the amounts of polyvinylpyrrolidone, tetrabutyl titanate, N,N-dimethylformamide, and anhydrous ethanol are 0.5~1.5 g, 0.5~1.5 g, 1~3 mL, and 6~10 mL, respectively.

[0012] Optionally, in the heat treatment, the temperature is raised to 500-700℃ at a rate of 2-5℃ / min, and the holding time at the crystallization temperature is 1-3h.

[0013] On the other hand, the present invention provides defect WO 3-x @FerroelectricBa 1-x Pr x The application of TiO3 composite nanocrystals, the defect WO 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals are used to prepare photoelectrodes, forming a three-electrode structure with a counter electrode and a reference electrode, using seawater as the electrolyte for optical signal detection.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: In seawater photoelectric detection applications, the synergistic effects of ferroelectric polarization modulation, defect-enhanced light absorption, heterojunction carrier separation, and interface corrosion protection give the photoelectrode constructed from composite nanocrystals three core advantages: first, high carrier separation efficiency ensures detection sensitivity; second, wide spectral response characteristics improve adaptability to complex marine light environments; and third, the stable heterojunction structure and corrosion resistance of the ferroelectric matrix ensure long-term operational stability, ultimately achieving highly sensitive and fast-response photoelectric detection in seawater environments. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 WO synthesized in Example 1 of this invention 3-x @Ba 0.95 Pr 0.05 Scanning electron microscope image of TiO3 composite nanocrystals; Figure 2 WO synthesized in Example 1 of this invention 3-x @Ba 0.95 Pr 0.05 X-ray photoelectron spectroscopy of TiO3 composite nanocrystals; Figure 3 Ferroelectric Ba synthesized in Example 2 of this invention 0.95 Pr 0.05 Ferroelectric hysteresis curve of TiO3 nanofilm; Figure 4 WO synthesized in Example 1 of this invention 3-x @Ba 0.95 Pr 0.05 Comparison of photocurrent response of TiO3 composite nanocrystals and materials prepared in the comparative example in seawater environment. Figure 5 WO synthesized in Example 1 of this invention 3-x @Ba 0.95 Pr 0.05 Photocurrent stability test results of TiO3 composite nanocrystals in seawater environment. Detailed Implementation

[0016] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] This invention relates to a defect WO for seawater photoelectric detection. 3-x @FerroelectricBa 1-x Pr x Preparation and application of TiO3 composite nanocrystals. The composite nanocrystals are based on Pr 3+ Doped Ba 1-x Pr x Using TiO3 ferroelectric material as the core, WO3 with oxygen vacancy defects is grown in situ on the surface. 3-x Nanocrystals form heterojunctions. The preparation method includes preparing Ba... 1-x Pr x TiO3 precursor sol was spin-coated to form a film; WO3 was then processed using WCl6 ethanol solution. 3-x Modification and secondary spin coating; finally, high-temperature crystallization treatment, utilizing the reducing atmosphere of polymer carbonization and WCl6 decomposition in air to synergistically introduce and regulate WO3. 3-x The oxygen vacancy concentration in the ferroelectric material was adjusted to obtain composite nanocrystals. This invention improves the separation efficiency, light absorption range, and corrosion resistance of photogenerated carriers through the synergistic effect of the polarization field of the ferroelectric material and defect engineering. The prepared composite nanocrystals can be used to construct photoelectrodes, exhibiting high sensitivity, rapid response, and good stability in seawater environments, showing promising applications in marine environmental monitoring and other fields.

[0018] This invention provides a defect WO for seawater photoelectric detection. 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals, wherein the composite nanocrystals are composed of Pr 3+ Doped Ba 1-x Pr x Using TiO3 as the core, WO3 with oxygen vacancy defects is grown in situ on the surface. 3-x Nanocrystals form a heterojunction structure.

[0019] Specifically, the oxygen vacancy defects are introduced by the reducing atmosphere generated during polymer carbonization and the decomposition of WCl6 during high-temperature crystallization, and the defect concentration is controlled by the heat treatment temperature and holding time.

[0020] On the other hand, the present invention provides for the aforementioned defects WO 3-x @FerroelectricBa 1-x Pr x The preparation method of TiO3 composite nanocrystals includes the following steps: (1) Preparation of Ba 1-x Pr x TiO3 precursor sol: Dissolve Ba(OH)2·H2O and Pr(NO3)3·6H2O in 4 mL of glacial acetic acid and stir continuously for 10-30 minutes until fully dissolved. Then, add 0.5-1.5 g of polyvinylpyrrolidone (PVP, number average molecular weight Mw ≈ 1,300,000) and tetrabutyl titanate (C...) to the solution sequentially. 16 H 36 O4Ti), 1~3 mL N,N-dimethylformamide (DMF) and 6~10 mL anhydrous ethanol, and stirred continuously for 2~10 h to form a uniform and stable precursor sol; (2) Spin-coating film formation: The above precursor sol is spin-coated onto the pre-cleaned FTO conductive glass: first, it is rotated at 800~1000 r / min for 10~20 s, and then at 2000~3000 r / min for 10~20 s, to form a uniform and dense wet film on the surface of the FTO conductive glass, namely Ba 1-x Pr x TiO3 precursor film surface.

[0021] (3)WO 3-x Modification: Dissolve tungsten source WCl6 in 50 mL of ethanol and stir for 1-2 h to form a blue solution. Add this solution dropwise to the Ba obtained in step (2). 1-x Pr x The TiO3 precursor film surface was then spin-coated at a speed of 500-1000 r / min for 10-20 s to ensure uniform coverage of the tungsten source. (4) High-temperature crystallization to form composite nanocrystals: The composite film treated in step (3) is placed in a tube furnace and heat-treated in an air atmosphere. The temperature is increased to 500-700℃ at a heating rate of 2-5℃ / min and held for 1-3 hours to carry out high-temperature crystallization treatment. The WO3 content is adjusted by controlling the crystallization temperature and the holding time. 3-x The oxygen vacancy content in the WO3 was determined by natural cooling to obtain defective WO3. 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals.

[0022] Specifically, in step (1), Ba(OH)2·H2O, Pr(NO3)3·6H2O and C 16 H 36The amount of O4Ti used must ensure that the molar ratio of Ba:Pr:Ti satisfies (1-x):x:1, where x ranges from 0 to 0.15. Here, x represents Ba... 1- x Pr x In TiO3, the parameter controlling the molar ratio of Ba:Pr is used. When x is 0, it is advisable not to add Pr.

[0023] Specifically, in step (3), the amount of WCl6 used needs to be such that the final WO3 is formed... 3-x with Ba 1-x Pr x The molar ratio of TiO3 was controlled between 0.3 and 3.0:1.0. Among them, WO3... 3-x In this context, x represents the existence of W. 6+ / W 5+ Therefore WO 3-x The stoichiometric ratio is not complete.

[0024] On the other hand, the present invention provides for the aforementioned defects WO 3-x @FerroelectricBa 1-x Pr x The application of TiO3 composite nanocrystals in seawater photoelectric detection involves preparing the composite nanocrystals into photoelectrodes (working electrodes), which together with counter electrodes and reference electrodes form a three-electrode system. Simulated seawater or actual seawater is used as the electrolyte for optical signal detection.

[0025] The following is a detailed description of the above technical solution: To address the problems of low sensitivity, poor charge separation efficiency, and insufficient stability of existing optoelectronic materials in seawater photoelectric detection, this invention provides a defect-free method for seawater photoelectric detection. 3-x @FerroelectricBa 1-x Pr x The preparation method and application of TiO3 composite nanocrystals are presented. By constructing a "ferroelectric-defect semiconductor" composite structure, the surface and interface control of the defect semiconductor is combined with the spontaneous polarization field of the ferroelectric material to achieve a synergistic effect of spectral absorption broadening and photogenerated charge separation enhancement. At the same time, the corrosion resistance and long-term stability of the material in the seawater environment are improved, which meets the practical application requirements of seawater photoelectric detection.

[0026] This invention specifically uses Pr 3+ Doped Ba 1-x Pr x TiO3 ferroelectric materials, through Pr 3+Doping modulates the spontaneous polarization intensity of ferroelectric materials, forming a stable built-in polarization field that provides the driving force for the directional separation of photogenerated carriers. The molar ratio of Ba:Pr:Ti is (1-x):x:1, with x ranging from 0 to 0.15. This doping range ensures the stability of both the ferroelectric properties and the crystal structure. Subsequently, in Ba… 1-x Pr x In-situ growth of WO3 with oxygen vacancy defects on the TiO3 core surface 3-x In nanocrystals, oxygen vacancy defects can act as carrier trapping sites to suppress photogenerated carrier recombination, while also adsorbing OH groups. - Or H2O molecules, accelerate the water oxidation reaction, thereby repelling Cl. - The function of WO. 3-x with Ba 1-x Pr x The molar ratio of TiO3 was controlled at 0.3~3.0:1.0 to ensure WO3 content. 3-x Uniform coating and smooth charge transport at the heterojunction interface.

[0027] The method for preparing the above-mentioned composite nanocrystals includes the following steps: (1) Preparation of Ba 1-x Pr x TiO3 precursor sol: using Ba(OH)2·H2O as the barium source, Pr(NO3)3·6H2O as the praseodymium source, and tetrabutyl titanate (C 16 H 36 Using O4Ti as the titanium source, polyvinylpyrrolidone (PVP, Mw≈1,300,000) as the dispersant, N,N-dimethylformamide (DMF) as the solvent regulator, and anhydrous ethanol as the diluent, a stoichiometric ratio of Ba(OH)2·H2O and Pr(NO3)3·6H2O was dissolved in 4 mL of glacial acetic acid, and stirred continuously for 10–30 minutes until completely dissolved. Then, 0.5–1.5 g of PVP, a stoichiometric amount of tetrabutyl titanate, 1–3 mL of DMF, and 6–10 mL of anhydrous ethanol were added sequentially, and the mixture was stirred continuously for 2–10 h to form a homogeneous and stable Ba4Ti titanium source. 1-x Pr x TiO3 precursor sol.

[0028] (2) Spin coating: The FTO conductive glass is ultrasonically cleaned in sequence with deionized water, ethanol and acetone, and then dried for later use; The precursor sol prepared in step (1) was drop-coated onto the pretreated FTO conductive glass, and a two-step spin-coating method was used to form a film: first, the film was spin-coated at 800~1000 r / min for 10~20 s, and then at 2000~3000 r / min for 10~20 s, to form a uniform and dense Ba film. 1-x Pr x TiO3 precursor wet film.

[0029] (3)WO 3-x Modification: Dissolve a measured amount of tungsten source WCl6 in 50 mL of ethanol and stir for 1-2 h to form a uniform blue WCl6 ethanol solution; add the WCl6 ethanol solution dropwise to the Ba obtained in step (2). 1-x Pr x On the surface of the TiO3 precursor film, spin-coating is performed at a speed of 500~1000 r / min for 10~20 s to ensure that the tungsten source is uniformly covered on the surface of the precursor film, thus achieving WO3. 3-x In-situ pre-modification.

[0030] (4) High-temperature crystallization to form composite nanocrystals: The composite film treated in step (3) is placed in a tube furnace and subjected to high-temperature crystallization in an air atmosphere; the temperature is increased to 500-700℃ at a heating rate of 2-5℃ / min and held for 1-3 h; during the high-temperature crystallization process, the PVP in the precursor undergoes a carbonization reaction, forming a reducing micro-atmosphere locally in the film. This reducing atmosphere works synergistically with the decomposition process of WCl6 in WO 3-x Oxygen vacancy defects are introduced into the substrate; the concentration of oxygen vacancy is precisely controlled by adjusting the crystallization temperature (500~700℃) and holding time (1~3 h); after high-temperature crystallization, the substrate is naturally cooled to room temperature to obtain defective WO3 on the FTO substrate. 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals.

[0031] This invention also discloses the above-mentioned WO 3-x @FerroelectricBa 1-x Pr x Application of TiO3 composite nanocrystals in photoelectric detection in seawater environments. Specifically, in the photoelectric detection process in seawater environments, the composite nanocrystals are used as the working electrode. Under light excitation with a power of 20~100 W, the working electrode can generate a stable photocurrent signal, achieving efficient photoelectric signal conversion, and thus completing the photoelectric detection of relevant parameters of the seawater environment.

[0032] The technical principles of the above-mentioned technical solutions are explained as follows: This invention is based on the core mechanism of ferropolar polarization regulation and defect engineering synergistic enhancement, and constructs defect WO 3-x @FerroelectricBa 1-x Pr x The TiO3 heterojunction system achieves synergistic optimization of photogenerated carrier separation efficiency, light absorption range, and corrosion resistance stability.

[0033] First, during the high-temperature heat treatment process, a double crystallization reaction occurs: one is Ba 1-x Prx The organic components (PVP, solvent residues, etc.) in the TiO3 precursor decompose, and the metal ions undergo lattice rearrangement to form a perovskite-type ferroelectric crystal structure, Pr 3+ Successfully replaced part of Ba 2+ Lattice sites regulate the ferroelectric properties of the material; secondly, the loaded WCl6 decomposes at high temperature to generate WO3 nanocrystals, which in Ba 1-x Pr x In-situ growth of TiO3 cores allows for the formation of core-shell heterojunctions through interfacial bonding (such as Ti-OW bonds). One factor is the localized reducing atmosphere created by the carbonization of polymers like PVP at high temperatures, which promotes the partial reduction of oxygen in the WO3 lattice. 2- The first is the removal of the crystal lattice; the second is the Cl produced during the decomposition of WCl6. - It reacts with lattice oxygen, further inducing the formation of oxygen vacancies. By controlling the heat treatment temperature (500~700℃) and holding time (1~3 h), the intensity of the reducing atmosphere and the degree of detachment of lattice oxygen can be precisely controlled, thereby achieving WO3 production. 3-x Adjustability of oxygen vacancy concentration: The higher the temperature and the longer the holding time, the higher the oxygen vacancy defect content, and vice versa.

[0034] Secondly, this invention specifically selects the rare earth element Pr, which has a similar ionic radius to Ba, to dope and modify BaTiO3. Through Pr... 3+ Doped Ba 1-x Pr x TiO3 ferroelectric matrix exhibits controllable spontaneous polarization characteristics, and the built-in polarization field it generates can form a directional potential gradient. This gradient can break the random recombination trend of photogenerated electron-hole pairs, enabling directional migration and spatial separation of charge carriers, reducing the charge carrier recombination energy barrier from a thermodynamic perspective, and improving charge carrier utilization efficiency.

[0035] Ultimately, oxygen vacancies are defect sites in crystals, increasing the concentration of free electrons in the material. In alkaline seawater solutions, hydroxylation (adsorption of OH groups) occurs on the surface of metal oxides. - The formation of M-OH groups makes the material surface negatively charged. The negatively charged metal oxide surface layer electrostatically repels similarly negatively charged Cl- groups. - This forms an "energy barrier" to prevent Cl from forming. - Approaching and adsorbing onto the photoelectrode surface, significantly reducing Cl - It has the potential to directly participate in oxidation reactions (chlorine evolution reaction) or to permeate and corrode electrode materials.

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments: Example 1 Defects of the present invention WO3-x @Ba 0.95 Pr 0.05 The preparation method of TiO3 composite nanocrystals includes the following steps: (1) Preparation of Ba by sol-gel method 0.95 Pr 0.05 TiO3 precursor film: Using 0.71 g Ba(OH)2·H2O as the barium source and 87 mg Pr(NO3)3·6H2O as the praseodymium source, the two raw materials were added to 4 mL of glacial acetic acid solution at a Ba:Pr molar ratio of 95:5. The mixture was magnetically stirred at room temperature for 30 min until completely dissolved, forming a homogeneous metal ion mixture solution. Subsequently, according to Ba… 0.95 Pr 0.05 TiO3 was stoichiometrically added to 1.3 mL of tetrabutyl titanate, followed by the sequential addition of 8 mL of anhydrous ethanol, 2 mL of N,N-dimethylformamide, and 1.0 g of polyvinylpyrrolidone. The mixture was magnetically stirred for 12 h to prepare a homogeneous and stable BaO3 solution. 0.95 Pr 0.05 TiO3 precursor sol; the precursor sol was transferred to a benchtop spin coater and coated onto a pretreated FTO conductive glass substrate using a two-step spin coating process: first, spin coating at a low speed of 800 r / min for 10 s, then spin coating at a high speed of 2000 r / min for 10 s, to obtain Ba 0.95 Pr 0.05 TiO3 precursor thin film.

[0037] (2) Preparation of WO3 by in-situ growth on the surface 3-x @Ba 0.95 Pr 0.05 TiO3 composite nanocrystals: A blue WCl6 ethanol solution was prepared by dissolving 150 mg WCl6 as a tungsten source in 50 mL of anhydrous ethanol and stirring magnetically for 2 h; this WCl6 ethanol solution was then dropwise coated onto the BaO3 nanocrystals obtained in step (1). 0.95 Pr 0.05 The TiO3 precursor film surface was spin-coated a second time at 800 r / min for 10 s on a benchtop spin coater. The composite precursor film was then transferred to a tube furnace and gradually heated to 600 ℃ at a rate of 2 ℃ / min in air atmosphere, held at that temperature for 2 h, and then naturally cooled to room temperature to obtain WO3 with good crystallinity. 3-x @Ba 0.95 Pr 0.05 TiO3 composite nanocrystals.

[0038] Example 2 Defects of the present invention WO 3-x @Ba 0.97 Pr 0.03The preparation method of TiO3 composite nanocrystals includes the following steps: (1) Preparation of Ba by sol-gel method 0.97 Pr 0.03 TiO3 precursor film: Using 0.72 g Ba(OH)2·H2O as the barium source and 52.2 mg Pr(NO3)3·6H2O as the praseodymium source, the two raw materials were added to 4 mL of glacial acetic acid solution at a Ba:Pr molar ratio of 97:3. The mixture was magnetically stirred at room temperature for 30 min until completely dissolved, forming a homogeneous metal ion mixture solution. Subsequently, according to Ba… 0.97 Pr 0.03 TiO3 was stoichiometrically added to 1.3 mL of tetrabutyl titanate, followed by the sequential addition of 8 mL of anhydrous ethanol, 2 mL of N,N-dimethylformamide, and 1.1 g of polyvinylpyrrolidone. The mixture was magnetically stirred for 10 h to prepare a homogeneous and stable BaO3 solution. 0.97 Pr 0.03 TiO3 precursor sol was transferred to a benchtop spin coater and coated onto a pretreated FTO conductive glass substrate using a two-step spin coating process: first, spin coating at a low speed of 1000 r / min for 10 s, then spin coating at a high speed of 2000 r / min for 15 s, to obtain Ba. 0.97 Pr 0.03 TiO3 precursor thin film.

[0039] (2) Preparation of WO3 by in-situ growth on the surface 3-x @Ba 0.97 Pr 0.03 TiO3 composite nanocrystals: A blue WCl6 ethanol solution was prepared by dissolving 150 mg WCl6 as a tungsten source in 50 mL of anhydrous ethanol and stirring magnetically for 2 h; this WCl6 ethanol solution was then dropwise coated onto the BaO3 nanocrystals obtained in step (1). 0.97 Pr 0.03 The TiO3 precursor film surface was spin-coated a second time at 1000 r / min for 10 s on a benchtop spin coater. The composite precursor film was then transferred to a tube furnace and gradually heated to 500 ℃ at a rate of 2 ℃ / min in air atmosphere, held at that temperature for 2 h, and then naturally cooled to room temperature to obtain WO3 with good crystallinity. 3-x @Ba 0.97 Pr 0.03 TiO3 composite nanocrystals.

[0040] Example 3 Defects of the present invention WO 3-x @Ba 0.92 Pr 0.08 The preparation method of TiO3 composite nanocrystals includes the following steps: (1) Preparation of Ba by sol-gel method0.92 Pr 0.08 TiO3 precursor film: Using 0.73 g Ba(OH)2·H2O as the barium source and 139.2 mg Pr(NO3)3·6H2O as the praseodymium source, the two raw materials were added to 4 mL of glacial acetic acid solution at a Ba:Pr molar ratio of 92:8. The mixture was magnetically stirred at room temperature for 30 min until completely dissolved, forming a homogeneous metal ion mixture solution. Subsequently, according to Ba… 0.92 Pr 0.08 TiO3 was stoichiometrically added to 1.3 mL of tetrabutyl titanate, followed by the sequential addition of 10 mL of anhydrous ethanol, 3 mL of N,N-dimethylformamide, and 1.5 g of polyvinylpyrrolidone. The mixture was magnetically stirred for 10 h to prepare a homogeneous and stable BaO3 solution. 0.92 Pr 0.08 TiO3 precursor sol was transferred to a benchtop spin coater and coated onto a pretreated FTO conductive glass substrate using a two-step spin coating process: first, spin coating at a low speed of 1000 r / min for 15 s, followed by spin coating at a high speed of 3000 r / min for 15 s, to obtain Ba. 0.92 Pr 0.08 TiO3 precursor thin film.

[0041] (2) Preparation of WO3 by in-situ growth on the surface 3-x @Ba 0.92 Pr 0.08 TiO3 composite nanocrystals: A blue WCl6 ethanol solution was prepared by dissolving 150 mg WCl6 as a tungsten source in 50 mL of anhydrous ethanol and stirring magnetically for 2 h; this WCl6 ethanol solution was then dropwise coated onto the BaO3 nanocrystals obtained in step (1). 0.92 Pr 0.08 The TiO3 precursor film surface was spin-coated a second time at 800 r / min for 15 s on a benchtop spin coater. The composite precursor film was then transferred to a tube furnace and gradually heated to 700℃ at a rate of 2℃ / min in air atmosphere, held at that temperature for 3 h, and then naturally cooled to room temperature to obtain WO3 with good crystallinity. 3-x @Ba 0.92 Pr 0.08 TiO3 composite nanocrystals.

[0042] Comparative Example 1 The ferroelectric Ba of the present invention 0.95 Pr 0.05 The preparation method of TiO3 nanofilm includes the following steps: Preparation of ferroelectric Ba by sol-gel method 0.95 Pr 0.05TiO3 nanofilm: Using 0.71 g Ba(OH)2·H2O as the barium source and 87 mg Pr(NO3)3·6H2O as the praseodymium source, the two raw materials were added to 4 mL of glacial acetic acid solution at a Ba:Pr molar ratio of 95:5. The mixture was magnetically stirred at room temperature for 30 min until completely dissolved, forming a homogeneous metal ion mixed solution. Subsequently, according to Ba… 0.95 Pr 0.05 TiO3 was stoichiometrically added to 1.3 mL of tetrabutyl titanate, followed by the sequential addition of 8 mL of anhydrous ethanol, 2 mL of N,N-dimethylformamide, and 1.0 g of polyvinylpyrrolidone. The mixture was magnetically stirred for 12 h to prepare a homogeneous and stable BaO3 solution. 0.95 Pr 0.05 TiO3 precursor sol was transferred to a benchtop spin coater and coated onto a pretreated FTO conductive glass substrate using a two-step spin coating process: first, spin coating at a low speed of 800 r / min for 10 s, followed by high speed spin coating at 2000 r / min for 10 s, to obtain a dense wet film; then, this wet film was transferred to a tube furnace and heated to 500 ℃ at a heating rate of 2 ℃ / min in air atmosphere, held at that temperature for 2 h, and naturally cooled to room temperature to obtain a uniform and dense ferroelectric Ba. 0.95 Pr 0.05 TiO3 nanofilm.

[0043] Comparative Example 2 The preparation method of BaTiO3 nanofilm is as follows: Using Ba(OH)₂·H₂O as the barium source, 0.75 g of the barium source was added to 4 ml of glacial acetic acid solution and magnetically stirred at room temperature for 30 min until completely dissolved, forming a homogeneous metal ion mixture solution. Subsequently, 1.3 mL of tetrabutyl titanate was added according to the stoichiometric ratio of BaTiO₃, followed by the addition of 10 mL of anhydrous ethanol, 3 mL of N,N-dimethylformamide, and 1.2 g of polyvinylpyrrolidone. Magnetic stirring was continued for 12 h to prepare a homogeneous and stable BaTiO₃ precursor sol. The precursor sol was transferred to a benchtop spin coater and coated onto a pretreated FTO conductive glass substrate using a two-step spin coating process: first, spin coating at a low speed of 800 r / min for 10 s, then at a high speed of 2000 r / min for 10 s, to obtain a dense wet film. This wet film was then transferred to a tubular calcination furnace and heated to 600 ℃ at a heating rate of 2 ℃ / min under air atmosphere, and calcined for 2 hours. After naturally cooling to room temperature, a uniform and dense BaTiO3 nanofilm was obtained.

[0044] Comparative Example 3 WO 3-x The preparation method of nanocrystals is as follows: Using WCl6 as the tungsten source, 200 mg of tungsten source was added to 50 ml of ethanol solution and magnetically stirred at room temperature for 2 h until completely dissolved, forming a blue transparent mixed solution. The mixed solution was then transferred to a benchtop spin coater and coated onto a pretreated FTO conductive glass substrate using a spin-coating process: spin-coating at 800 r / min for 10 s yielded a dense wet film. This wet film was then transferred to a tube furnace and heated to 600 ℃ at a heating rate of 3 ℃ / min in air atmosphere, held at that temperature for 2 h, and naturally cooled to room temperature to obtain WO3 with good crystallinity. 3-x Nanocrystals.

[0045] Images of the material prepared in Example 1 observed under a scanning electron microscope, such as... Figure 1 As shown, the composite nanocrystals exhibit a nanoscale microstructure: the material is composed of nanocrystals, each of which is uniformly dispersed within the field of view without obvious agglomeration; the size of individual nanocrystals is concentrated in the range of 2~4 nm, clearly demonstrating the nanoscale grain characteristics of the composite nanocrystals, which is consistent with the design of the target composite nanostructure.

[0046] Take the X-ray photoelectron spectrum of the material prepared in Example 1, as shown below. Figure 2 As shown, this graph directly indicates the defect WO 3-x @Ba 0.95 Pr 0.05 The TiO3 composite nanocrystals contain oxygen in various chemical states, and oxygen vacancy defects have been successfully introduced, which is consistent with the design requirements of the defect-type composite structure of the composite nanocrystals.

[0047] Take the ferroelectric hysteresis loop image of the material obtained in Example 2, as shown below. Figure 3 As shown, the curve exhibits a typical closed ferroelectric PE hysteresis loop, with a regular shape and good symmetry. With the cyclic changes in the positive and negative directions of the applied electric field, the polarization intensity of the material synchronously shows a reversible increase or decrease response, reflecting the Ba... 0.95 Pr 0.05 TiO3 possesses stable ferroelectric polarization properties, which aligns with the electrical property design requirements of the target functional material.

[0048] Figures 4 and 5 show the photocurrent response comparison and photocurrent stability test schematic diagrams of the materials prepared in Examples 1-2 and Comparative Examples 1-2 under simulated seawater conditions, respectively. These figures are for systematic evaluation of the effects of Pr doping modification and WO3. 3-x The synergistic optimization effect of in-situ growth composites on the photoelectric detection performance of materials was tested. An electrolyte composed of 0.5 mol / L NaCl and 1 mol / L KOH was used to simulate the seawater corrosion environment. A 100 W xenon lamp light source (simulating the spectral characteristics of sunlight) was used as the light excitation condition to quantitatively compare the photoelectric response performance of different samples.

[0049] like Figure 4 As shown, compared to Comparative Example 1 (pure BaTiO3) and Comparative Example 2 (pure WO3), 3-x ), the WO prepared in the embodiments of the present invention 3-x @Ba 0.95 Pr 0.05 TiO3 composite nanocrystals exhibited significantly enhanced photoelectric conversion efficiency, with a peak photocurrent response exceeding 100 μA. Compared to the photocurrent response values ​​of the two single-component comparative materials, this represents an improvement of up to 100 times, fully demonstrating the lattice distortion introduced by Pr doping and the effect of WO3 on the photocurrent response. 3-x The combined synergistic effect of the defect structure effectively promotes the separation and transport of photogenerated carriers, and significantly optimizes the photoelectric response performance of the material.

[0050] like Figure 5 As shown, the present invention WO 3-x @Ba 0.95 Pr 0.05 Under the synergistic effect of 800 s continuous light irradiation and simulated seawater electrolyte, the photocurrent intensity of the TiO3 composite nanocrystals remained stable without any attenuation, indicating that the composite material possesses excellent resistance to seawater corrosion and can effectively resist Cl in seawater environments. - The effective rejection significantly improves the long-term service stability of the material in harsh chlorine-containing environments, providing key performance support for its practical application in the field of marine photoelectric detection.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A defect WO used for seawater photoelectric detection 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals, characterized in that: With Pr 3+ Doped Ba 1-x Pr x Using TiO3 ferroelectric material as the core, WO3 with oxygen vacancy defects is grown in situ on the surface of the core. 3-x Nanocrystals, the core and surface in situ grown WO4 3-x Nanocrystals form heterojunction structures.

2. The defect WO according to claim 1 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals, characterized in that... The WO 3-x Oxygen vacancy defects in nanocrystals are introduced during high-temperature crystallization, which are introduced by the reducing atmosphere generated by polymer carbonization and the decomposition of WCl6 during high-temperature crystallization; the concentration of oxygen vacancy defects is adjusted by the temperature and holding time during high-temperature crystallization.

3. The defect WO based on any one of claims 1-2 3-x @FerroelectricBa 1-x Pr x The method for preparing TiO3 composite nanocrystals is characterized by, include: Ba(OH)2·H2O and Pr(NO3)3·6H2O were dissolved in glacial acetic acid. After stirring and dissolving, polyvinylpyrrolidone, tetrabutyl titanate, N,N-dimethylformamide and anhydrous ethanol were added to the solution in sequence and stirred to form a precursor sol. The precursor sol was spin-coated onto conductive glass to form Ba on the conductive glass. 1-x Pr x TiO3 precursor thin film; Dissolve WCl6 in ethanol and stir to form a first solution. Add the first solution dropwise to Ba. 1-x Pr x The surface of the TiO3 precursor film was spin-coated to achieve uniform coverage, thus obtaining a composite film. The composite film is placed in a tube furnace and subjected to high-temperature crystallization under an air atmosphere. The heat treatment includes uniform heating and holding at the crystallization temperature. The WO3 content is adjusted by controlling the crystallization temperature and the holding time. 3-x The oxygen vacancy content in the sample, after cooling, yields defective WO3. 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals.

4. The preparation method according to claim 3, characterized in that, The Ba(OH)2·H2O, Pr(NO3)3·6H2O and C 16 H 36 In the O4Ti dosage, the molar ratio of Ba:Pr:Ti is (1-x):x:1, where the value of x ranges from 0 to 0.

15.

5. The preparation method according to claim 3, characterized in that, The amount of WCl6 used determines the final formation of WO. 3-x with Ba 1-x Pr x The molar ratio of TiO3 is controlled between 0.3 and 3.0:1.

0.

6. The preparation method according to claim 3, characterized in that, The conductive glass is FTO conductive glass.

7. The preparation method according to claim 3, characterized in that, The amounts of polyvinylpyrrolidone, N,N-dimethylformamide, and anhydrous ethanol used are 0.5~1.5 g, 1~3 mL, and 6~10 mL, respectively.

8. The preparation method according to claim 3, characterized in that, In the heat treatment, the temperature is raised to 500-700℃ at a rate of 2-5℃ / min, and the holding time at the crystallization temperature is 1-3 h.

9. The defect WO based on any one of claims 1-2 3-x @FerroelectricBa 1-x Pr x The application of TiO3 composite nanocrystals is characterized by... The defect WO 3-x @FerroelectricBa 1-x Pr x TiO3 composite nanocrystals are used to prepare photoelectrodes, forming a three-electrode structure with a counter electrode and a reference electrode, using seawater as the electrolyte for optical signal detection.

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