Bi25-xErxFeO40 piezoelectric crystal, preparation method thereof and application of Bi25-xErxFeO40 piezoelectric crystal in catalytic degradation of organic pollutants
By doping Bi25FeO40 with Er, a cubic Bi25-xErxFeO40 piezoelectric crystal was prepared, which solved the problems of low built-in polarization electric field strength and insufficient carrier separation ability, and achieved efficient degradation of organic pollutants under dark and stirred conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI UNIV OF SCI & TECH
- Filing Date
- 2026-02-28
- Publication Date
- 2026-05-05
AI Technical Summary
Bi25FeO40 piezoelectric crystals suffer from low built-in polarization field strength and insufficient carrier separation capability, which limits their actual efficiency in pollutant degradation.
By doping Bi25FeO40 with Er, a cubic Bi25-xErxFeO40 piezoelectric crystal was prepared. The preparation method included steps such as dissolving metal salt compounds, adjusting pH value, and hydrothermal reaction to form a piezoelectric crystal with spin polarization.
The built-in electric field strength of Bi25-xErxFeO40 crystals was enhanced, improving the piezoelectric catalytic degradation ability under dark and stirred conditions, thus achieving efficient degradation of organic pollutants and effective degradation even without light irradiation.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention belongs to the field of piezoelectric functional materials, and relates to an Er-doped Bi. 25-x Er x FeO 40 Piezoelectric crystals, their preparation methods, and their applications in the catalytic degradation of organic pollutants. Background Technology
[0002] Piezoelectric catalysis technology can utilize mechanical energy to drive chemical reactions, providing a new pathway for the degradation of water pollutants. 25 FeO 40 Composed of alternating bismuth-rich [Bi-O] polyhedral units and Fe-O ligands, its non-centrosymmetric bismuthite-type framework structure endows it with piezoelectric effects, making it considered one of the piezoelectric catalysts with broad application prospects. However, Bi... 25 FeO 40 It still faces problems such as low built-in polarization electric field strength and insufficient carrier separation capability, which limit its actual efficiency in pollutant degradation. Summary of the Invention
[0003] To address the problems existing in the prior art, the present invention provides a Bi 25-x Er x FeO 40 The piezoelectric crystal, its preparation method, and its application in the catalytic degradation of organic pollutants can achieve piezoelectric degradation of pollutants under stirred and dark conditions, or under stirred and light conditions, and can restore its piezoelectric catalytic degradation ability under dark and stirred conditions.
[0004] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a Bi 25-x Er x FeO 40 piezoelectric crystal, the Bi 25-x Er x FeO 40 Piezoelectric crystals are cubic crystal systems with space group 123, where x = 0.188~0.340.
[0005] Secondly, the present invention provides a Bi 25-x Er x FeO 40 Methods for preparing piezoelectric crystals include: Step 1: Dissolve Bi(NO3)3·5H2O, Er(NO3)3·5H2O and Fe(NO3)3·9H2O in ethylene glycol, and then add water to obtain a mixed solution; Step 2: Under stirring conditions, add NH3·H2O to the mixed solution to adjust the pH value to 9~11, and a precipitate will be generated. The precipitate will be washed and dried in sequence. Step 3: The dried precipitate is mixed with NaOH solution to obtain a precursor solution; the precursor solution undergoes a hydrothermal reaction, and the resulting product is washed and dried to obtain Bi. 25-x Er x FeO 40 Piezoelectric crystal.
[0006] Preferably, in step 1, the molar ratio of Bi(NO3)3·5H2O, Er(NO3)3·5H2O and Fe(NO3)3·9H2O is (1~y):y:1, where y = 0.07~0.12.
[0007] Preferably, in step 1, the volume ratio of ethylene glycol to water is 50:(50~80).
[0008] Preferably, in step 2, the stirring time is 100-120 min. In step 2 of this invention, NH3·H2O is used to adjust the pH value, and NH4... + Washing and drying are easy to remove. However, if KOH, NaOH, or LiOH are used to adjust the pH value, the Na... + K + and Li + Washing and drying are not easy to remove the precipitates, which affects their electronegativity. Bi(OH)3, Er(OH)3, and Fe(OH)3 precipitates adsorb metal ions, which affects their polymerization into large molecular networks.
[0009] Preferably, in step 3, the hydrothermal reaction temperature is 165~200℃ and the hydrothermal reaction time is 30~48 h.
[0010] Preferably, in step 3, the washing process specifically involves: first washing with deionized water by centrifugation, then washing with anhydrous ethanol, and repeating this process several times.
[0011] Preferably, in step 3, the drying is vacuum drying.
[0012] Thirdly, the present invention provides a Bi 25-x Er x FeO 40 Application of piezoelectric crystals in the catalytic degradation of organic pollutants.
[0013] Preferably, the catalytic degradation of organic pollutants is carried out under stirring and dark conditions, or under stirring and light conditions.
[0014] The Bi 25-x Er x FeO 40Piezoelectric crystals possess piezoelectric properties, and Er doping breaks the Bi... 25-x Er x FeO 40 The spin equilibrium state of electrons within the crystal produces spin polarization, which enhances the properties of Bi. 25-x Er x FeO 40 The built-in electric field strength of the crystal. The Bi 25- x Er x FeO 40 Bii piezoelectric crystals enhanced by spin polarization under stirring and darkness conditions, or under stirring and illumination conditions. 25-x Er x FeO 40 The built-in electric field strength of the crystal enables efficient piezoelectric catalytic degradation of organic pollutants, and can restore its piezoelectric catalytic degradation ability under dark and stirred conditions.
[0015] Preferably, the organic pollutant is tetracycline hydrochloride, ciprofloxacin, and bisphenol A.
[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention is in Bi 25 FeO 40 Er doping in piezoelectric crystals modulates the properties of Bi. 25 FeO 40 The valence state distribution of Fe and Bi elements and the charge density distribution within the crystal altered the local charge structure, enhanced the saturation magnetic field strength, and increased the Bi content. 25-x Er x FeO 40 Crystal spin polarization, under the action of spin polarization, Bi 25-x Er x FeO 40 Piezoelectric crystals enhance the intensity of the built-in polarization electric field. Under dark / full-spectrum conditions, the applied mechanical stirring force promotes the release of stored charges, the formation and separation of piezoelectric / photogenerated charges, thereby improving the ability to mineralize and degrade water pollutants.
[0017] This invention Bi 25-x Er x FeO 40 The crystal possesses the ability to piezoelectrically catalyze the degradation of organic pollutants, independent of light conditions. (Bi) 25-x Er x FeO 40Crystals can efficiently convert mechanical energy into chemical energy, enabling pollutant degradation under dark conditions. They exhibit enhanced piezoelectric mineralization degradation capabilities for organic pollutants under both dark and full-spectrum conditions, and can restore their piezoelectric catalytic degradation capabilities under both dark and stirred conditions. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 The XRD patterns are of the piezoelectric crystals prepared in Comparative Example 1 and Examples 1-6.
[0020] Figure 2 This is a SEM image of the piezoelectric crystal prepared in Example 5.
[0021] Figure 3 The image shown is an HRTEM image of the piezoelectric crystal prepared in Example 5.
[0022] Figure 4 The image shows the EDS diagram of the piezoelectric crystal prepared in Example 5.
[0023] Figure 5 High-resolution XPS images of Bi 4f of the piezoelectric crystals prepared in Comparative Examples 1, 3 and 5.
[0024] Figure 6 High-resolution XPS images of Fe 2p piezoelectric crystals prepared in Comparative Examples 1, 3 and 5.
[0025] Figure 7 High-resolution XPS images of the piezoelectric crystals prepared in Comparative Examples 1, 3 and 5 (O 1s).
[0026] Figure 8 Hysteresis loop diagrams of the piezoelectric crystals prepared in Comparative Example 1 and Example 5.
[0027] Figure 9 The piezoelectric crystal prepared in Example 5 was tested in the dark for 20 mg·L⁻¹ -1 Absorbance curve of methylene blue.
[0028] Figure 10 The image shows the EPR of holes in the piezoelectric crystal prepared in Example 5 under darkness.
[0029] Figure 11The transient piezoelectric current diagram is generated by the piezoelectric crystal prepared in Comparative Example 1 under mechanical stirring force.
[0030] Figure 12 The transient piezoelectric current diagram is generated by the piezoelectric crystal prepared in Example 5 under mechanical stirring force.
[0031] Figure 13 The PFM phase change diagram is shown for the piezoelectric crystal prepared in Example 5.
[0032] Figure 14 The graph shows the PFM amplitude variation of the piezoelectric crystal prepared in Example 5.
[0033] Figure 15 The image shows the KPFM morphology of the piezoelectric crystal prepared for Comparative Example 1.
[0034] Figure 16 The KPFM surface potential distribution of the piezoelectric crystal prepared for Comparative Example 1 is shown.
[0035] Figure 17 The KPFM average surface potential diagram of the piezoelectric crystal prepared for Comparative Example 1.
[0036] Figure 18 The image shows the KPFM morphology of the piezoelectric crystal prepared in Example 5.
[0037] Figure 19 The image shows the KPFM surface potential distribution of the piezoelectric crystal prepared in Example 5.
[0038] Figure 20 The KPFM average surface potential diagram of the piezoelectric crystal prepared in Example 5.
[0039] Figure 21 Zeta potential values of the piezoelectric crystals prepared in Comparative Example 1 and Example 5.
[0040] Figure 22 The image shows the built-in electric field intensity of the piezoelectric crystals prepared in Comparative Example 1 and Example 5.
[0041] Figure 23 The degradation curves of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under dark conditions.
[0042] Figure 24 The rate constant diagram for the degradation of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under dark conditions.
[0043] Figure 25 The piezoelectric crystal prepared in Example 5 was tested under dark conditions for 40 mg·L⁻¹ -1 TC TOC removal rate graph.
[0044] Figure 26The images show the cyclic degradation of the piezoelectric crystal prepared in Example 5 under dark conditions and the degradation after energy storage.
[0045] Figure 27 The graph shows the TOC removal rate of the piezoelectric crystal prepared in Example 5 after cycling and energy storage degradation under dark conditions.
[0046] Figure 28 Degradation rates of BPA and CIP by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under dark conditions.
[0047] Figure 29 The degradation curves of TC under visible light for the piezoelectric crystals prepared in Comparative Example 1 and Example 5.
[0048] Figure 30 The rate constant diagram for the degradation of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under visible light.
[0049] Figure 31 The piezoelectric crystal prepared in Example 5 exhibits resistance to 40 mg·L⁻¹ light under visible light. -1 TC TOC removal rate graph.
[0050] Figure 32 The images show the cyclic degradation of the piezoelectric crystal prepared in Example 5 under visible light and its degradation after energy storage.
[0051] Figure 33 The degradation rate of BPA and CIP by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under visible light is shown in the graph.
[0052] Figure 34 The degradation curves of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under near-infrared light.
[0053] Figure 35 The rate constant diagram for the degradation of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under near-infrared light.
[0054] Figure 36 The piezoelectric crystal prepared in Example 5 exhibits resistance to 40 mg·L⁻¹ of near-infrared light. -1 TC TOC removal rate graph.
[0055] Figure 37 The images show the cyclic degradation of the piezoelectric crystal prepared in Example 5 under near-infrared light and its degradation after energy storage.
[0056] Figure 38 The degradation rate of BPA and CIP by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under near-infrared light is shown in the graph.
[0057] Figure 39The degradation curves of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under simulated sunlight.
[0058] Figure 40 The rate constant diagram for the degradation of TC by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under simulated sunlight.
[0059] Figure 41 The piezoelectric crystal prepared in Example 5 was subjected to 40 mg·L⁻¹ sunlight. -1 TC TOC removal rate graph.
[0060] Figure 42 The images show the cyclic degradation of the piezoelectric crystal prepared in Example 5 under simulated sunlight and its degradation after energy storage.
[0061] Figure 43 The degradation rate of BPA and CIP by the piezoelectric crystals prepared in Comparative Example 1 and Example 5 under simulated sunlight is shown in the graph. Detailed Implementation
[0062] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0063] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.
[0064] Comparative Example 1 Step 1: Mix Fe(NO3)3·9H2O and Bi(NO3)3·5H2O in a 1:1 molar ratio. 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve in 50 mL of ethylene glycol, and after complete dissolution, add 80 mL of deionized water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 by NH3·H2O to quickly generate a precipitate. The precipitate is then washed and dried in sequence. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 25 FeO 40 Piezoelectric crystal catalyst.
[0065] Example 1 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.93:0.07:1, and Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.812 Er 0.188 FeO 40 Piezoelectric crystal.
[0066] Example 2 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.92:0.08:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.783 Er 0.217 FeO 40 Piezoelectric crystal.
[0067] Example 3 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.91:0.09:1, with Fe... 3+ Er3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.753 Er 0.247 FeO 40 Piezoelectric crystal.
[0068] Example 4 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.90:0.10:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.723 Er 0.277 FeO 40 Piezoelectric crystal.
[0069] Example 5 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0070] Example 6 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.88:0.12:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.66 Er 0.34 FeO 40 Piezoelectric crystal.
[0071] Example 7 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 30 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0072] Example 8 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 40 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0073] Example 9 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 42 h, followed by washing and drying. 24.692 Er0.308 FeO 40 Piezoelectric crystal.
[0074] Example 10 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 48 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0075] Example 11 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 170 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0076] Example 12 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 185 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0077] Example 13 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 190℃ for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0078] Example 14 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 200 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0079] Example 15 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: Stir the mixed solution with a magnetic stirrer for 100 min, adjust the pH of the mixed solution to 10 with NH3·H2O to produce a precipitate, and wash and dry the precipitate in sequence; Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0080] Example 16 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 105 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0081] Example 17 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 115 min. The pH value of the mixed solution is adjusted to 10 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0082] Example 18 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: Stir the mixed solution with a magnetic stirrer for 120 min, adjust the pH of the mixed solution to 10 with NH3·H2O to produce a precipitate, and wash and dry the precipitate in sequence; Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0083] Example 19 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 9 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0084] Example 20 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 80 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 11 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er0.308 FeO 40 Piezoelectric crystal.
[0085] Example 21 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 50 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 11 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0086] Example 22 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 60 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 11 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0087] Example 23 Step 1: Mix Bi(NO3)3·5H2O, Er(NO3)3·5H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.89:0.11:1, with Fe... 3+ Er 3+ and Bi 3+ The total concentration is 0.2 mol·L⁻¹ -1 Dissolve it in 50 mL of ethylene glycol, then add 70 mL of water to obtain a mixed solution; Step 2: The mixed solution is stirred under magnetic stirring for 110 min. The pH value of the mixed solution is adjusted to 11 using NH3·H2O to produce a precipitate. The precipitate is then washed and dried sequentially. Step 3: Transfer the above precipitate to a polytetrafluoroethylene reactor and add 40 mL of 5 mol·L⁻¹ solution. -1 Bi was prepared by reacting a solution of NaOH at 165 °C for 36 h, followed by washing and drying. 24.692 Er 0.308 FeO 40 Piezoelectric crystal.
[0088] Piezoelectric catalysis experiment: Degradation experiments were conducted on an XPA-7 photochemical reactor (Nanjing Xujiang Machinery Factory). The specific procedures were as follows: 50 mg of piezoelectric crystals were weighed and dispersed in 20 mg·L⁻¹ solution. -1 The solution was tested for TC, BPA, and CIP. Under dark conditions, approximately 5 mL of solution was taken every 1 minute and filtered through a 0.22 μm membrane. The absorbance of the filtrate was measured using a UV spectrophotometer (SP-756P). The absorbance at the wavelength of maximum absorption was used to characterize the degradation efficiency of the piezoelectric crystal on the target pollutant. The residual concentration of the pollutant, A, was determined, and the initial concentration was denoted as A0. The degradation rate was calculated using the following formula: The characteristic absorption wavelength of TC is 358 nm; that of BPA is 278 nm; that of CIP is 272 nm; and that of methylene blue (MB) is 666 nm.
[0089] Piezoelectric photocatalysis experiment: by adjusting the initial concentration of 20 mg·L -1 The photocatalytic degradation performance of piezoelectric crystals was evaluated using TC, BPA, and CIP photodegradation experiments. A 500W xenon lamp was used to simulate sunlight (190 nm–2500 nm), and a 500W xenon lamp with a filter was used to simulate near-infrared light (QFS2500 + 800 long-pass filter, 800 nm–2500 nm). Photodegradation experiments were conducted on an XPA-7 photochemical reactor (Nanjing Xujiang Electromechanical Plant). In a typical experiment, 50 mg of piezoelectric crystal was dispersed in 20 mg·L⁻¹ solution. -1The suspension was placed in 50 mL solutions of TC, BPA, and CIP. During illumination, 5 mL of the suspension was periodically centrifuged, filtered through a 0.22 μm membrane, and the absorbance of the filtrate was measured.
[0090] The concentration of total organic carbon (TOC) was determined using an automated TOC analyzer (Liqui-TOC) to assess the degree of mineralization of organic pollutants.
[0091] The following provides a detailed explanation of the above conclusions and mechanisms.
[0092] Figure 1 The XRD patterns are for Comparative Example 1, Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6. The diffraction peaks at 24.705°, 27.683°, 30.388°, 32.889°, and 35.288° correspond to Bi1 in a cubic crystal system with space group 123. 25 FeO 40 (JCPDS NO. 46-4016). The diffraction peaks at 22.417°, 31.753°, and 32.068° belong to the trigonal crystal system, space group R3C:H, twisted rhombohedral perovskite structure of BiFeO3 (JCPD NO. 86-1518). Comparative Example 1 is Bi... 25 FeO 40 Crystal. Compared to Comparative Example 1, the diffraction peaks of Examples 1-6 shifted to higher angles, indicating that the large-radius Bi... 3+ Er with smaller radius 3+ Replacement, realized Er 3+ Successful doping. Examples 1-4 contained a small amount of BiFeO3. As the Er doping amount increased, the diffraction peaks of BiFeO3 gradually weakened and disappeared, and there were no other impurity phases, indicating that Er doping inhibited the formation of BiFeO3.
[0093] Figure 2 Bi prepared in Example 5 25-x Er x FeO 40 SEM images of piezoelectric crystals show that Bi2O3 can be observed. 25-x Er x FeO 40 Piezoelectric crystals are composed of square nanosheets with a side length of 170 ~ 950 nm and a thickness of 80 nm and nanoparticles.
[0094] Figure 3 Bi prepared in Example 5 25-x Er x FeO 40 The HRTEM image of the piezoelectric crystal clearly shows lattice fringes of 0.321 nm, corresponding to Bi...25-x Er x FeO 40 The (310) crystal plane.
[0095] Figure 4 Bi prepared in Example 5 25-x Er x FeO 40 The EDS diagram of the piezoelectric crystal, showing the uniform distribution of Bi, Fe, O, and Er elements, confirms the successful doping of Bi with Er. 25 FeO 40 In crystals.
[0096] Figure 5 The high-resolution Bi4f plots of the piezoelectric crystals of Comparative Example 1, Example 3, and Example 5 are shown. The double peaks at 158.6 / 163.94 eV and 159.35 / 164.8 eV of the piezoelectric crystal of Comparative Example 1 correspond to Bi4f values at 158.6 / 163.94 eV and 159.35 / 164.8 eV, respectively. 3+ and Bi 5+ Bi in the piezoelectric crystals prepared in Comparative Examples 1, 3, and 5 3+ / Bi 5+ The contents of Er-doped Bi were 67.38% / 32.62%, 80.75% / 20.25%, and 79.13% / 20.87%, respectively. 5+ The partial reduction indicates that Er modulates the electronic structure and increases the charge density around Bi.
[0097] Figure 6 The high-resolution Fe 2p plots for Comparative Example 1, Example 3, and Example 5 show that the peak at 711.3 eV in the piezoelectric crystal of Comparative Example 1 belongs to Fe. 2+ The peaks at 712.9 eV and 724.9 eV belong to Fe. 3+ Fe in the piezoelectric crystals prepared in Comparative Examples 1, 3, and 5 2+ / Fe 3+ The contents were 14.06% / 85.94%, 11.86% / 88.14%, and 13.74% / 86.26%, respectively. After doping, Bi... 25 FeO 40 Fe 2+ The concentration decreases, which indicates a reduction in the charge density around Fe.
[0098] Figure 7The high-resolution O 1s plots of the piezoelectric crystals of Comparative Example 1, Example 3, and Example 5 show the peaks at 533.8 eV, 531.62 eV, and 530.73 eV, which correspond to adsorbed hydroxyl oxygen, oxygen vacancies, and lattice oxygen, respectively. The oxygen vacancy contents in the piezoelectric crystals prepared in Comparative Example 1, Example 3, and Example 5 are 56.63%, 29.73%, and 33.56%, respectively.
[0099] Figure 8 The diagram shows the hysteresis loops of the piezoelectric crystals in Comparative Example 1 and Example 5. The saturation magnetic field strength of the piezoelectric crystal in Example 5 is 5.92 emu·g. -1 The piezoelectric crystal of Comparative Example 1 (1.42 emu·g) -1 The concentration of Bi prepared in Example 5 was 4.17 times that of Bi, indicating that the Bi concentration was 4.17 times that of Bi prepared in Example 5. 25-x Er x FeO 40 It exhibits enhanced spin polarization. Compared to Bi in Comparative Example 1... 25 FeO 40 Compared to the case where the proportion of electrons with spin-up and spin-down is equal, the Bi in Example 5... 25-x Er x FeO 40 The difference between the two spin states of electrons enhances spin polarization.
[0100] according to Figure 9 MB decolorization experiment and Figure 10 The quantum spin number estimated the electron and hole concentrations stored in the piezoelectric crystal of Example 5 to be 12.47 μmol·g⁻¹. -1 and 38.73 μmol·g -1 This indicates that due to the presence of oxygen vacancies and variable valence ion defects, the Bi prepared in this invention... 25-x Er x FeO 40 It has energy storage characteristics.
[0101] Figure 11 and Figure 12 The figures show the transient piezocurrents generated by the piezoelectric crystals of Comparative Example 1 and Example 5 under mechanical stirring in dark conditions, respectively. When mechanical stirring is applied, the Bi... 25 FeO 40 and Bi 25-x Er x FeO 40 The absolute values are 3.40 × 10⁻⁶ respectively. -2 μA and 5.75×10 -2 The transient piezoelectric current plot with an amplitude of μA indicates that the Bi prepared in this invention 25-x Er x FeO 40It has stronger mechanical sensitivity.
[0102] Figure 13 The phase change diagram of the piezoelectric crystal in Example 5 shows that, under pulsed DC voltage (±10 V) mode, the phase angle flips by approximately 180°. Furthermore... Figure 14 The amplitude-voltage curve exhibits a "butterfly ring" shape caused by the piezoelectric field and dipole motion, confirming that Bi 25-x Er x FeO 40 A piezoelectric polarization field exists within the crystal, exhibiting the piezoelectric effect; the piezoelectric coefficient can be calculated. d 33 5.55 nm·V -1 .
[0103] Figure 15 and Figure 18 The KPFM morphology images of the piezoelectric crystals of Comparative Example 1 and Example 5 are shown respectively, indicating that Er doping has a significant impact on grain growth and surface morphology. Figure 16 and Figure 19 The KPFM surface potential distributions of the piezoelectric crystals in Comparative Example 1 and Example 5 are shown respectively. The surface potential distributions of the piezoelectric crystals in Comparative Example 1 and Example 5 are -130.9 mV to -18.6 mV and -372.6 mV to -282.3 mV, respectively. Figure 17 and Figure 20 The KPFM average surface potential diagrams for the piezoelectric crystals of Comparative Example 1 and Example 5 are shown below. The average surface potential (V) of the piezoelectric crystals of Comparative Example 1 and Example 5 are also shown. s The values were -42.27 mV and -31.057 mV, respectively. Figure 21 The Zeta potentials (ζ) of the piezoelectric crystals in Comparative Example 1 and Example 5 are 4.89 mV and 4.58 mV, respectively. Figure 22 The built-in electric field strength (F) of the piezoelectric crystal in Example 5 was calculated using the average surface potential and Zeta potential. s实施例5 The electric field strength of the Bi piezoelectric crystal prepared in this invention is 2.62 times that of the piezoelectric crystal in Example 1, confirming the effectiveness of this invention. 25-x Er x FeO 40 It features enhanced spin polarization and built-in electric field strength, and possesses energy storage and piezoelectric effects.
[0104] Figure 23 Under dark conditions, with mechanical stirring applied for 0–5 min, the piezoelectric crystals of Comparative Example 1 and Example 5 showed a reaction at 20 mg·L⁻¹. -1The degradation rates of tetracycline hydrochloride (TC) were 52.73% and 49.03%, respectively; under mechanical stirring for 5–30 min in the dark, the piezoelectric crystals of Comparative Example 1 and Example 5 showed degradation rates of 20 mg·L⁻¹. -1 The degradation rates of TC were 28.60% and 38.2%, respectively; after 30 min, the piezoelectric crystals of Comparative Example 1 and Example 5 showed a degradation rate of 20 mg·L⁻¹. -1 The degradation rates of TC were 81.33% and 87.23%, respectively. Figure 24 The pseudo-first-order reaction kinetic constant k corresponds to the piezoelectric crystals of Comparative Example 1 and Example 5. From 0 to 5 min, the k values for the piezoelectric crystals of Comparative Example 1 and Example 5 are 0.14987 min, respectively. -1 and 0.13479 min -1 ; 5~30 min, the k value of the piezoelectric crystals in Comparative Example 1 and Example 5 was 0.03623 min. -1 and 0.05765 min -1 . Figure 25 The results show that the TOC removal rates of the piezoelectric crystal in Example 5 were 45.82% and 72.03% at 5 min and 30 min, respectively. Figure 26 The piezoelectric crystal in Example 5 was shown to react with 20 mg·L⁻¹ after two cycles. -1 The degradation rate of TC decreased to 34.78%. After two cycles, the piezoelectric crystal of Example 5 was dispersed in pure water and mechanically stirred. Electrons and holes were re-stored within the piezoelectric crystal of Example 5. After 1 hour of re-energy storage, the piezoelectric crystal of Example 5 was effective against 20 mg·L⁻¹ of TC. -1 The degradation rate of TC recovered to 62.91%. Figure 27 The corresponding TOC removal rate increased from 28.72% to 51.35%, indicating that the Bi prepared in this invention... 25-x Er x FeO 25 The crystal possesses self-healing properties related to the dark cycle. Furthermore, Figure 28 The results showed that after 30 minutes in darkness, the piezoelectric crystal in Example 5 reacted with 20 mg·L⁻¹ -1 The degradation rates of bisphenol A (BPA) / ciprofloxacin (CIP) were 42.23% / 13.09%, which is higher than that of the pure-phase Bi prepared in Comparative Example 1. 25 FeO 40 The concentrations of Bi prepared in this invention are 1.69 and 6.23 times higher than those of Bi (BPA / 24.92%, CIP / 2.1%), confirming the effectiveness of the method. 25-x Er x FeO 25 The crystals possess enhanced broad-spectrum piezoelectric catalytic degradation capabilities.
[0105] Figure 29The piezoelectric crystals of Comparative Example 1 and Example 5 were demonstrated to exhibit their effect on 20 mg·L⁻¹ piezoelectricity under visible light. -1 The degradation curves of TC. The degradation rates of TC by the piezoelectric crystals of Comparative Example 1 and Example 5 were 51.27% and 48.94% in the first 5 min, respectively; 32% and 42.18% in the first 30 min, respectively; and 83.27% and 91.12% after 30 min, respectively. Figure 30 The corresponding degradation rate constant is k. For the time intervals from 0 to 5 min, the k values for the piezoelectric crystals in Comparative Example 1 and Example 5 are 0.14387 min and 0.14387 min, respectively. -1 and 0.13489min -1 For the time intervals from 5 to 30 minutes, the corresponding k values are 0.04210 min. -1 and 0.04778 min -1 . Figure 31 In Example 5, the TOC removal rates of the piezoelectric crystal at 5 min and 30 min were 53.07% and 76.21%, respectively. Figure 32 The results showed that after five cycles of the piezoelectric crystal in Example 5, the degradation rate of TC was 17.93%. After five cycles, the piezoelectric crystal of Example 5 was dispersed in pure water and mechanically stirred in the dark for 1 hour. Upon re-energy storage, the degradation rate of the piezoelectric crystal of Example 5 recovered to 53.55%. Figure 33 As shown, under visible light, the piezoelectric crystals of Comparative Example 1 and Example 5 showed a piezoelectric effect at 20 mg·L⁻¹. -1 The degradation rates of BPA and CIP were 27.51% / 4.75% and 68.09% / 30.23%, respectively.
[0106] Figure 34 The piezoelectric crystals of Comparative Example 1 and Example 5 were demonstrated to exhibit their effect on 20 mg·L⁻¹ piezoelectric light under near-infrared light. -1 Degradation curves of TC. The degradation rates of TC by the piezoelectric crystals of Comparative Example 1 and Example 5 were 48.26% and 47.98% in the first 5 min, respectively; 26.06% and 41.53% in the first 30 min, respectively; and 74.32% and 89.51% after 30 min, respectively. Figure 35 The corresponding degradation rate constant is k. For the time intervals from 0 to 5 min, the k values for the piezoelectric crystals in Comparative Example 1 and Example 5 are 0.13195 min and 0.13195 min, respectively. -1 and 0.13073 min -1 For the intervals of 5 to 30 minutes, the corresponding k values are 0.02847 min. -1 and 0.06482 min -1 . Figure 36In Example 5, the TOC removal rates of the piezoelectric crystal at 5 min and 30 min were 52.94% and 73.18%, respectively. Figure 37 The results showed that after five cycles of the piezoelectric crystal in Example 5, the degradation rate of TC was 17.67%. After five cycles, the piezoelectric crystal of Example 5 was dispersed in pure water and mechanically stirred in the dark for 1 hour. Upon re-energy storage, the degradation rate of the piezoelectric crystal of Example 5 recovered to 53.40%. Figure 38 As shown, under near-infrared light, Comparative Example 1 and Example 5 compared to 20 mg·L⁻¹ -1 The degradation rates of BPA and CIP were 25.35% / 2.78% and 51.71% / 28.97%, respectively.
[0107] Figure 39 The piezoelectric crystals of Comparative Example 1 and Example 5 were demonstrated to react with 20 mg·L⁻¹ piezoelectric crystals under simulated sunlight. -1 The degradation curves of TC. The degradation rates of TC by the piezoelectric crystals of Comparative Example 1 and Example 5 were 59.82% and 53.23% in the first 5 min, respectively; 30.49% and 38.44% in the first 30 min, respectively; and 90.31% and 91.67% after 30 min, respectively. Figure 40 The corresponding degradation rate constant is k. For the time intervals from 0 to 5 min, the k values for the piezoelectric crystals in Comparative Example 1 and Example 5 are 0.18243 min and 0.18243 min, respectively. -1 and 0.15201 min -1 For the time intervals from 5 to 30 minutes, the corresponding k values are 0.05635 min. -1 and 0.06533 min -1 . Figure 41 In Example 5, the TOC removal rates of the piezoelectric crystal at 5 min and 30 min were 54.06% and 76.17%, respectively. Figure 42 The results showed that after five cycles of the piezoelectric crystal in Example 5, the degradation rate of TC was 34.51%. After five cycles, the piezoelectric crystal of Example 5 was dispersed in pure water and mechanically stirred in the dark for 1 hour. Upon re-energy storage, the degradation rate of the piezoelectric crystal of Example 5 recovered to 62.96%. Figure 43 As shown, under simulated sunlight, the piezoelectric crystals of Comparative Example 1 and Example 5 showed a 20 mg·L⁻¹ test result. -1 The degradation rates of BPA and CIP were 32.14% / 5.48% and 59.37% / 34.22%, respectively.
[0108] This invention enhances the performance of Bi by modulating spin polarization. 25-x Er x FeO 40The built-in electric field strength of the piezoelectric crystal enables the piezoelectric degradation of pollutants under stirred and dark conditions, or under stirred and illuminated conditions, and can restore its piezoelectric catalytic degradation ability under dark and stirred conditions.
[0109] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.
Claims
1. Bi 25-x Er x FeO 40 Piezoelectric crystal, characterized in that, The Bi 25-x Er x FeO 40 Piezoelectric crystals are cubic crystal systems with space group 123, where x = 0.188~0.
340.
2. The Bi as described in claim 1 25-x Er x FeO 40 A method for preparing a piezoelectric crystal, characterized in that, include: Step 1: Dissolve Bi(NO3)3·5H2O, Er(NO3)3·5H2O and Fe(NO3)3·9H2O in ethylene glycol, and then add water to obtain a mixed solution; Step 2: Under stirring conditions, add NH3·H2O to the mixed solution to adjust the pH value to 9~11, and a precipitate will be generated. The precipitate will be washed and dried in sequence. Step 3: Mix the dried precipitate with NaOH solution to obtain the precursor solution; The precursor solution underwent a hydrothermal reaction, and the resulting product was washed and dried to obtain Bi. 25-x Er x FeO 40 Piezoelectric crystal.
3. The Bi according to claim 2 25-x Er x FeO 40 A method for preparing a piezoelectric crystal, characterized in that, In step 1, the molar ratio of Bi(NO3)3·5H2O, Er(NO3)3·5H2O and Fe(NO3)3·9H2O is (1~y):y:1, where y = 0.07~0.
12.
4. The Bi according to claim 2 25-x Er x FeO 40 A method for preparing a piezoelectric crystal, characterized in that, In step 1, the volume ratio of ethylene glycol to water is 50:(50~80).
5. The Bi according to claim 2 25-x Er x FeO 40 A method for preparing a piezoelectric crystal, characterized in that, In step 2, the stirring time is 100~120 min.
6. The Bi according to claim 2 25-x Er x FeO 40 A method for preparing a piezoelectric crystal, characterized in that, In step 3, the hydrothermal reaction temperature is 165~200℃ and the hydrothermal reaction time is 30~48 h.
7. The Bi as described in claim 1 25-x Er x FeO 40 Application of piezoelectric crystals in the catalytic degradation of organic pollutants.
8. The application according to claim 7, characterized in that, The catalytic degradation of organic pollutants was carried out under stirred and dark conditions.
9. The application according to claim 8, characterized in that, The Bi 25-x Er x FeO 40 After being recycled several times, the piezoelectric crystal is regenerated under dark and stirred conditions, and then used to catalyze the degradation of organic pollutants.
10. The application according to claim 7, characterized in that, The catalytic degradation of organic pollutants is carried out under stirring and light conditions.