Aromatic carbon-stable oxygen vacancy black titanium dioxide nanomaterial, preparation method thereof and water purification application

Abstract

This invention discloses a black titanium dioxide nanomaterial with aromatic carbon-stabilized oxygen vacancies, its preparation method, and its application in water purification. This material is a biomass-derived solvent-guided mesoporous black TiO2 nanomaterial with surface oxygen vacancies and bulk oxygen vacancies stabilized by doped aromatic carbon, suitable for solar-driven clean water production. Preparation method: Using a green biomass-derived solvent as the carbon source, carbon source solvent / H2O in different volume ratios is added to a mixture of titanium source and ethanol. A precursor gel is prepared by ultrasonic and solvothermal reaction. After washing, drying, and calcination, the mesoporous black TiO2 nanomaterial is obtained. The preparation method of this invention is simple and environmentally friendly. The prepared nanomaterial exhibits excellent photothermal and photocatalytic properties and can be integrated to construct high-performance aerogels for photothermal water evaporation and photodegradation, thereby achieving efficient light-driven water purification. This preparation method solves the related problems in the preparation and application of existing black TiO2, providing a sustainable strategy for solar-driven clean water production.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a black titanium dioxide nanomaterial with aromatic carbon stabilizing oxygen vacancies, its preparation method, and its application in water purification. Background Technology

[0002] Producing clean water from polluted sources is a critical challenge facing modern society, crucial for alleviating water scarcity, reducing environmental pollution, and enhancing ecological sustainability. Among various emerging water purification technologies, solar water evaporation strategies based on photothermal conversion processes have attracted widespread attention due to their potential for sustainable water purification. To date, various semiconductors have been developed as photothermal materials in solar interfacial evaporation systems. However, to completely remove contaminants from water and ensure that the purified water meets drinking water standards, it is essential to increase the density of reaction sites and the photogenerated charge separation efficiency of photothermal materials to promote the photocatalytic degradation of contaminants. However, photogenerated electron-hole pairs in semiconductors undergo two competing processes: when carrier migration efficiency is high, these charge carriers can drive the photocatalytic reaction; conversely, non-radiative recombination contributes to heat generation. Therefore, achieving a balance between photocatalysis and photothermal conversion mechanisms within a single photoresponsive semiconductor, resulting in bifunctional nanomaterials exhibiting highly efficient photothermal and photocatalytic performance, remains a significant challenge in this field.

[0003] Titanium dioxide (TiO2) has attracted widespread attention in multifunctional photoactive systems due to its tunable internal properties (such as defects and doping) and external properties (such as morphology and size) (Chem. Rev., 2024, 124(21): 11848-11914, Appl. Catal. B: Environ., 2017, 206: 336-343). Among these, defect engineering by introducing oxygen vacancies (OVs) has become an effective strategy for regulating the light absorption, electronic structure, charge transport, and overall photoactivity of TiO2 (Chem. Eng.J., 2020, 389: 123918). Bulk oxygen vacancies are beneficial for photothermal conversion, while surface oxygen vacancies can improve photocatalytic efficiency (Appl. Catal. B: Environ., 2018, 220: 126-136), but at the same time, bulk oxygen vacancies also migrate to the surface or subsurface regions. Therefore, designing TiO2 materials with stable bulk phase and surface oxygen vacancies provides a promising approach for combining photothermal and photocatalytic functions.

[0004] In existing synthetic methods, hydrothermal treatment, chemical reduction (NaBH4, Al, Mg), and oxidation methods have been used to prepare oxygen-vacancy TiO2 (Sci. Bull., 2017, 62(6): 431-441.). However, these top-down preparation methods involve high pressure or high temperature, which increases costs and limits large-scale production capabilities. Recently, a bottom-up strategy has emerged, which involves constructing low-valent Ti(VI) complexes with reducing agents, directly synthesizing Ti(VI) precursors using low-valent titanium compounds or hydrothermal methods, and then introducing oxygen vacancies through low-temperature calcination (at different atmospheres) (Chem. Eng. J., 2023, 460: 141734). This has become an effective and simple method for controlling oxygen vacancies.

[0005] Glycerin is a common byproduct of the oil and fat industry, and its value needs to be enhanced from the perspective of the circular economy. On an industrial scale, glycerin can be efficiently converted into glycerol ethers. By adjusting the hydrophilic glycerol backbone and the hydrophobic alkyl side chain, the amphiphilic properties of glycerol ethers can be altered, making them promising green and tunable solvents in the pharmaceutical, cosmetic, and catalytic fields (ACS Sustainable Chem. Eng., 7 (2019) 13004-13014, ACS Sustain. Chem. Eng., 2021, 9(19): 6875-6885). Meanwhile, solvents such as glycerol, glycerol, and ethylene glycol often serve as soft templates to form titanate precursors, which, through calcination, form Ti vacancies (Nano Energy 28 (2016) 296–303) and oxygen vacancies TiO2 (Nat. Commun. 2020, 11, 418). Inspired by this, asymmetric diglyceride was used as a mediating reducing agent in the preparation of black TiO2 nanomaterials. Its key role in finely controlling the surface and bulk oxygen vacancies of photoactive titanium dioxide in the controllable synthesis of multi-level polymer networks is particularly noteworthy. Summary of the Invention

[0006] The first technical problem to be solved by this invention is to provide a black titanium dioxide nanomaterial with carbon-stabilized oxygen vacancies, so as to overcome the shortcomings of existing TiO2 light-driven water purification technology and its oxygen vacancy TiO2 preparation process; this invention proposes a method for preparing a black titanium dioxide nanomaterial with aromatic carbon-stabilized oxygen vacancies controlled by a green solvent, realizing the controllable construction of surface oxygen vacancies, and stabilizing the bulk oxygen vacancies by doping with aromatic carbon, thereby enabling its use in solar-driven clean water production.

[0007] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned black titanium dioxide nanomaterial.

[0008] The third technical problem to be solved by the present invention is to provide the water purification application of the above-mentioned black titanium dioxide nanomaterials.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A method for preparing a black titanium dioxide nanomaterial with aromatic carbon-stabilized oxygen vacancies includes the following steps: (1) Dissolve the titanium source in an organic solvent, then add a mixed solution of carbon source and water, sonicate and then carry out a solvothermal reaction to obtain the precursor gel. (2) The precursor gel obtained in step (1) is washed, dried and calcined to obtain the final product.

[0011] In some embodiments, in step (1), the titanium source is an organic titanium source or an inorganic titanium source, preferably an organic titanium source; and / or, the organic titanium source is any one of tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate, or titanium isopropoxide, preferably tetrabutyl titanate; and / or, the inorganic titanium source is any one of titanium sulfate, titanium oxysulfate, titanium tetrachloride, or titanium trichloride; and / or, the organic solvent is ethanol; and / or, the carbon source is a glycerol ether diether having the structure shown in formula (I), the structural formula of which is as follows: .

[0012] In some embodiments, the glycerol ether diether is prepared according to the method described in ACS Sustainable Chemistry and Engineering 7, 15 (2019), 13004-13014.

[0013] In some embodiments, in step (1), the mass-to-volume ratio of the titanium source to the organic solvent is 0.2~2 g:5 mL, preferably 2 g:5 mL; and / or, the volume ratio of the carbon source to the water is 1~3:1, preferably 2:1; and / or, the mass-to-volume ratio of the titanium source to the mixed solution is 0.2~2 g:3 mL, preferably 2 g:3 mL; and / or, the ultrasonic treatment has a power of 20~40 kHz and a time of 15~30 min; and / or, the solvothermal reaction has a temperature of 90~250 ℃ (preferably 180 ℃) and a reaction time of 1~10 h, preferably 6 h.

[0014] In some embodiments, in step (2), the washing is performed using ethanol, and the number of times is 3 to 5, preferably 3 times; and / or, the drying is performed at a temperature of 60 to 80 ℃ (preferably 60 ℃) for 8 to 12 h, preferably 12 h; and / or, the calcination is performed in an air, nitrogen or argon atmosphere, with the temperature increased to 300 to 800 ℃ at a rate of 5 to 8 ℃ / min and then calcined for 1 to 10 h.

[0015] Preferably, the calcination is carried out in an air atmosphere by heating to 300 °C at a rate of 5 °C / min and then calcining for 2 h.

[0016] The black titanium dioxide nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared by the above method are also within the scope of protection of this invention.

[0017] A method for preparing a black titanium dioxide-based nanomaterial aerogel includes the following steps: dispersing the black titanium dioxide nanomaterial and sodium alginate in water to form a precursor mixed solution, freezing and molding to obtain a hydrogel, and then freeze-drying, calcium ion crosslinking, solid-liquid separation and drying treatment to obtain the final product.

[0018] In some embodiments, after freeze-forming and before freeze-drying, an aqueous solution of the black titanium dioxide nanomaterial is coated onto the surface of the hydrogel.

[0019] In some embodiments, the mass ratio of the black titanium dioxide nanomaterial to sodium alginate is 1~3:12, preferably 1:6; the mass-volume ratio of sodium alginate to water is 20~24 mg:1 mL, preferably 24 mg:1 mL; the freezing is performed at a temperature of -30 ℃ to -20 ℃ for 12~15 h; the freeze-drying is performed at a temperature of -50 ℃ to -30 ℃ (preferably -45 ℃) for 10~15 h (preferably 12 h) and a pressure of -0.5~-0.1 MPa, preferably -0.1 MPa; the calcium ion crosslinking is performed by immersing the freeze-dried sample in a 1~10 wt% calcium chloride aqueous solution for 1~4 h; the drying is performed at a temperature of 50~80 ℃ (preferably 80 ℃) for 6~8 h, preferably 6 h.

[0020] Preferably, the calcium ion crosslinking is performed by immersing the freeze-dried sample in a 5 wt% calcium chloride aqueous solution for 2 h; the amount of calcium chloride aqueous solution used is sufficient to completely submerge the sample.

[0021] In some embodiments, the concentration of the black titanium dioxide nanomaterial in the aqueous solution is 1~8 mg / mL, preferably 7.5 mg / mL.

[0022] A black titanium dioxide-based nanomaterial aerogel is also within the scope of protection of this invention.

[0023] This invention also protects the application of the black titanium dioxide nanomaterial with oxygen vacancies stabilized by aromatic carbon or the black titanium dioxide-based nanomaterial aerogel in photothermal evaporation, photocatalytic degradation of water pollutants, and reduction of Cr(VI); preferably, the water pollutants are methylene blue, rhodamine B, and methyl orange.

[0024] Beneficial effects:

[0025] (1) The method for preparing black titanium dioxide nanomaterials with aromatic carbon-stabilized oxygen vacancies provided by the present invention constructs black mesoporous TiO2 nanomaterials with high coexistence of bulk phase and surface OV through a simple hydrothermal calcination method. Among them, the biomass-derived solvent, such as glycerol diether D100, has unique structural composition / coordination characteristics. In the precursor gel obtained by reacting with the titanium source, its coordination bridges adjacent titanium atoms, thereby effectively enhancing the photoresponse characteristics of the material. Moreover, under low-temperature calcination conditions, the unsaturated coordination state of glycerol diether in an oxygen-rich atmosphere promotes the formation of surface oxygen vacancies; internally, its saturated coordination state in an oxygen-deficient atmosphere is conducive to the generation of bulk phase oxygen vacancies stabilized by aromatic carbon doping.

[0026] (2) Black titanium dioxide nanomaterials with aromatic carbon-stabilized oxygen vacancies, obtained by hydrothermal calcination, possess both good photothermal conversion and photocatalytic degradation performance; the further constructed aerogel material exhibits highly efficient light-driven water purification performance. This material demonstrates full solar spectrum light absorption, high photothermal efficiency, and excellent photocatalytic degradation performance of organic pollutants. The TiOC@SA-TiOC photothermal evaporator integrating sodium alginate (SA) achieved an excellent water evaporation rate of 2.61 kg m³ under one solar irradiation. -2 h -1 Furthermore, its light-driven water purification performance (water evaporation coupled degradation) was verified under natural sunlight.

[0027] (3) The preparation method provided by the present invention is simple, highly reproducible, and the preparation process is green and environmentally friendly. It has potential application prospects in environmental remediation and new material synthesis, and also provides new ideas for designing and synthesizing photocatalysts with oxygen vacancies and realizing multifunctional light-driven water purification technology. Attached Figure Description

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0029] Figure 1A schematic diagram of the preparation method of black TiO2 nanomaterials (TiOC-2) with oxygen vacancies stabilized by aromatic carbon;

[0030] Figure 2 Synthetic routes for glycerol diether D100 and glycerol monoether 100;

[0031] Figure 3 The 1H NMR spectrum of glycerol diether D100;

[0032] Figure 4 The image shows the carbon NMR spectrum of glycerol diether D100.

[0033] Figure 5 Here is the GC-MS chromatogram of glycerol diether D100;

[0034] Figure 6 SEM image of TiOC-2 prepared in Example 1;

[0035] Figure 7 The image shows a TEM image of TiOC-2 prepared in Example 1.

[0036] Figure 8 EPR and TGA images of the black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared in Examples 1-4;

[0037] Figure 9 XPS fine orbital spectra of Ti 2p and O 1s in the black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared in Examples 1-4;

[0038] Figure 10 EPR images of black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared in Examples 1 and 5-6;

[0039] Figure 11 Solid-state CP / MAS of solvent D100, precursor Ti(D100)2 and TiOC-2 prepared in Example 1 13 C NMR and FTIR spectra;

[0040] Figure 12 The photothermal response properties of TiOC-2 prepared in Example 1 were tested.

[0041] Figure 13 Digital photographs of SA, SA-TiOC-10 and TiOC@SA-TiOC-5 aerogels prepared for Examples 7-9;

[0042] Figure 14 SEM image of TiOC@SA-TiOC-5 aerogel prepared in Example 9;

[0043] Figure 15Aerogels prepared from black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies provided in Examples 7-9 under different implementation conditions are shown as time-dependent curves of the mass change of photothermal evaporation, as well as their photothermal evaporation rate and photothermal conversion efficiency.

[0044] Figure 16 The graph shows the cycling stability results of the TiOC@SA-TiOC-5 aerogel provided in Example 9;

[0045] Figure 17 The graph shows the changes in MB concentration with reaction time and the cycle stability of MB degradation by TiOC-2 prepared in Example 1.

[0046] Figure 18 The graph shows the photocatalytic degradation performance of MB by black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies provided in Examples 1 and 5-6.

[0047] Figure 19 This is a comparison of the photocatalytic performance of TiOC-2 prepared in Example 1 in degrading dyes and reducing Cr(VI) under different pH conditions;

[0048] Figure 20 The outdoor device and outdoor photothermal evaporation coupled photocatalytic degradation performance of MB provided in Example 9 are shown in the figure. Detailed Implementation

[0049] In this embodiment of the invention, the experimental methods described are conventional methods unless otherwise specified; the reagents described are commercially available unless otherwise specified.

[0050] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0051] This invention provides a method for preparing black titanium dioxide nanomaterials with aromatic carbon stabilizing oxygen vacancies. The specific preparation process is as follows: Figure 1 .

[0052] The synthesis of the glyceryl diether (D100) used in this invention follows the general steps described by Pires et al. (ACS Sustainable Chemistry and Engineering 7, 15 (2019), 13004-13014, Glycerol-derived solutions: synthesis and properties of symmetric glyceryl diethers) (reaction formulas are as follows). Figure 2 As shown in the figure. Specifically, methanol (22.5 mol) and KOH (0.6 mol) were placed in a 2 L isothermal reactor equipped with a mechanically stirred Teflon paddle and an external cooling jacket. Under an argon atmosphere and at 65 °C, 3 mol of glycidyl ether (2,3-epoxypropanol) was added dropwise to the homogeneous mixture and the reaction proceeded. After 1 h, the reactor system was cooled to 20 °C after the glycidyl ether was completely consumed by gas chromatography. The solution was neutralized with dilute HCl, and the formed salt was filtered out. To obtain the dimer D100, a vacuum fractionation process (approximately 3 × 10⁻⁶) was employed. -3 (bar) First, trace amounts of methanol were removed by heating at 40 °C. Then, the temperature was raised to 112 °C to obtain glycerol ether monoether 100 (222.8 g, 2.1 mol) in 70% yield. Finally, the obtained glycerol ether diether D100 (162.1 g, 0.9 mol) was obtained in 30% yield.

[0053] Proton NMR, carbon NMR, and mass spectrometry data ( Figures 3-5 ): 1 H NMR (400 MHz, DMSO- d 6) δ 4.77 (dd, J = 5.1, 2.0 Hz, 1H), 4.61 (dd, J = 5.0, 1.8 Hz, 1H), 4.48 (t, J = 5.7 Hz, 1H), 3.70 (dt, J = 5.6, 5.1 Hz, 1H), 3.58 – 3.52 (m, 1H), 3.44 – 3.34 (m, 4H), 3.34 – 3.28 (m,4H), 3.24 (s, 3H); 13 C NMR (101 MHz, DMSO- d 6) δ 74.15, 72.87, 72.78, 70.46, 68.33, 63.03, 58.34; GC-MS(ESI+): found at 181.15, theoretical calculated value 181.10 [M+H + ].

[0054] Example 1

[0055] 2 g (2 mL) of tetrabutyl titanate was dissolved in 5 mL of ethanol, and then 3 mL of a D100 / H2O (volume ratio 2:1) mixed solution was added. The mixture was then sonicated (40 kHz, 15 min). The solution was then transferred to a 15 mL stainless steel Teflon-lined autoclave and subjected to a solvothermal reaction at 180 °C for 6 h to obtain the precursor gel Ti(D100)2. The gel was washed three times with ethanol and then air-dried at 60 °C for 12 h. Finally, under air atmosphere, the temperature was increased to 300 °C at a heating rate of 5 °C / min and calcined for 2 h to obtain black TiO2 nanomaterials with mesoporous aromatic carbon-stabilized oxygen vacancies (TiOC-2).

[0056] In this embodiment, the role of D100 is as a surfactant and soft template agent to facilitate the formation of different carbon-doped oxygen vacancy structures.

[0057] Example 2

[0058] The preparation method in this embodiment is the same as that in Example 1, except that the volume ratio of the D100 / H2O mixed solution is 0:1, and the resulting material is (TiOC-0).

[0059] Example 3

[0060] The preparation method in this embodiment is the same as that in Example 1, except that the volume ratio of the D100 / H2O mixed solution is 1:1, and the resulting material is (TiOC-1).

[0061] Example 4

[0062] The preparation method in this embodiment is the same as that in Example 1, except that the volume ratio of the D100 / H2O mixed solution is 3:1, and the resulting material is (TiOC-3).

[0063] Example 5

[0064] The preparation method in this embodiment is the same as that in Example 1, except that the calcination temperature of the muffle furnace is changed to 400℃ / 2 h.

[0065] Example 6

[0066] The preparation method in this embodiment is the same as that in Example 1, except that the calcination temperature of the muffle furnace is changed to 500℃ / 2 h.

[0067] Example 7

[0068] 10 mg TiOC-2 and 60 mg sodium alginate (SA) were dispersed in 2.5 mL of aqueous solution and magnetically stirred until a homogeneous TiOC / SA mixture was formed. The TiOC / SA mixture was transferred to a custom mold (cylindrical, 35 mm diameter at the bottom, 58 mm high, 40 mL volume, and 2 mm wall thickness) and frozen at -20°C for 12 h to obtain SA-TiOC hydrogel. The frozen sample was freeze-dried at -45°C and -0.1 MPa for 12 h, and then... 2+ Cross-linking (i.e., immersing the dried sample in a 5wt% CaCl2 solution for 2 h to improve the mechanical strength of SA, with the amount of CaCl2 solution used to completely submerge the sample), followed by separation and drying in a forced-air dryer (80°C, 6 h) to obtain SA-TiOC-10 aerogel.

[0069] In this embodiment, SA plays a role in constructing a three-dimensional network of TiO2-based hydrogels, dispersing and stabilizing TiO2 particles, and enhancing the mechanical properties of the material. The role of TiOC-2 is as a photothermal and photocatalytic material for photothermal evaporation and water pollutant treatment.

[0070] Example 8

[0071] The difference between this embodiment and Example 7 is that, using the same method described above, 0 mg, 5 mg and 15 mg TiOC-2 were added to prepare SA, SA-TiOC-5 and SA-TiOC-15 aerogels, respectively.

[0072] Example 9

[0073] The difference between this embodiment and Embodiment 7 is that, using the same method described above, 2 mL of an aqueous solution of TiOC-2 (2.5, 5, 10, 15 mg) was coated onto the top surface of the frozen SA-TiOC hydrogel, followed by freeze-drying and Ca... 2+ Crosslinking and drying processes were used to prepare TiOC@SA-TiOC-2.5, TiOC@SA-TiOC-5, TiOC@SA-TiOC-5, TiOC@SA-TiOC-10, and TiOC@SA-TiOC-15 aerogels, respectively.

[0074] Comparative Example 1

[0075] Commercial titanium dioxide P25 was used as a control sample.

[0076] Example 10

[0077] Material characterization

[0078] The mesoporous aromatic carbon-stabilized black TiO2 nanomaterial (TiOC-2) prepared in Example 1 was subjected to SEM testing, and the test results are as follows: Figure 6 As shown. Low-magnification SEM ( Figure 6 a) The material appears as a loose aggregate structure; high-magnification SEM images ( Figure 6 b) It can be seen that the nanoparticles have a uniform particle size distribution, indicating that this method can prepare nanomaterials with good morphology and good monodispersity.

[0079] TEM test, such as Figure 7 As shown, anatase (101) and (200) are the dominant crystalline phases, and amorphous regions are observed on both the surface and the interior, which is attributed to the introduction of OV and carbon doping. Combined with the transmission electron microscopy (TEM) analysis results, the average particle size of the nanomaterial is about 4.5 nm.

[0080] To investigate the oxygen vacancy concentration and carbon doping content of the materials, electron paramagnetic resonance (EPR) was performed on the samples from Examples 1-4. Figure 8 a), and thermogravimetric analysis (TGA) Figure 8 (b) The EPR signal is strongest when the D100 / H2O volume ratio is 2. Surface OVs are typically stable with electrons paired with chemisorbed oxygen, which makes the signal detected by EPR spectroscopy mainly the bulk OV containing a single trapped electron (Appl. Catal. B: Environ., 2017, 206: 300-307). Therefore, the black TiO2 nanomaterial with aromatic carbon-stabilized oxygen vacancies prepared in Example 1 has the highest relative content of oxygen vacancies. Meanwhile, thermogravimetric analysis shows that the weight loss exceeding 300℃ is related to the decomposition of the carbon dopant. Based on the weight loss conversion, the carbon contents are 0.72 wt% (TiOC-0), 2.33 wt% (TiOC-1), 4.47 wt% (TiOC-2), and 6.98 wt% (TiOC-3), respectively. A positive correlation between the D100 / H2O volume ratio and carbon content was observed.

[0081] Combining the EPR and TGA results, it can be seen that the carbon content and oxygen vacancy concentration are not simply linearly positively correlated: an appropriate amount of carbon doping (TiOC-2, 4.47 wt%) can effectively induce the formation of oxygen vacancies, while an excessively high carbon content (TiOC-3, 6.98 wt%) will inhibit the formation of oxygen vacancies. This indicates that when the D100 / H2O volume ratio is 2, the synergistic optimization of carbon doping and oxygen vacancy concentration can be achieved.

[0082] XPS fine spectra of Ti 2p and O 1s for the samples prepared in Examples 1-4 show that at 458.6 eV (Ti 2p... 3 / 2 ) and 464.4 eV (Ti 2p 1 / 2 Two main peaks are shown at position ) corresponding to Ti. 4+ Species ( Figure 9 a). Furthermore, the weak satellite peak values ​​of 457.9 eV and 463.7 eV are attributed to Ti. 3+ O is typically found near oxygen vacancies. In the O 1s XPS spectrum of TiOC-n (n=1-3), three distinct peaks were identified at 529.8 eV, 531.7 eV, and 532.3 eV, corresponding to lattice oxygen (O₂) and lattice oxygen (O₂). latt ), and chemisorbed oxygen (O) associated with stable surface oxygen vacancies abs ) and oxygen (O-H2O) from adsorbed water species ( Figure 9 b). Ti 3+ / Ti 4+ Changes in area ratio and O abs / (O latt The proportions of TiOC-2 (+O-H2O) showed a similar trend, with TiOC-2 showing the highest value of 35.0%, while TiOC-0 showed no Ti. 3+ Signal. This indicates that Ti 4+ / Ti 3+ The partial reduction is due to the generation of surface oxygen vacancies in TiOC-n (n=1-3), which further confirms the existence of oxygen vacancies in TiOC-n (n=1-3).

[0083] The EPR of the samples prepared in Examples 1 and 5-6 are shown below. Figure 10 The oxygen vacancy signal was strongest at 300℃, and the EPR signal decreased as the temperature increased, indicating that the oxygen vacancy was restored by the oxygen element in the oxygen.

[0084] The formation mechanism of oxygen vacancies in the black TiO2 nanomaterial with aromatic carbon-stabilized oxygen vacancies prepared in Example 1 was analyzed. The solid-state carbon spectra and FTIR of solvent D100, precursor Ti(D100)2 and TiOC-2 were characterized, and their respective chemical compositions were analyzed. The reaction mechanism of TiOC preparation by directional thermal decomposition of glycerol diether D100 coordinating Ti atoms to form a gel was then deduced.

[0085] like Figure 11 As shown in figure a, solid Ti(D100)2 13 The C100 NMR spectrum showed six sharp peaks and a broad peak at 81 ppm, corresponding to two environments: physisorbed free D100 and titanium-coordinated glycerate. After calcination at 300 °C, the 81 ppm signal disappeared, and a new broad peak appeared at 125 ppm, indicating that D100 decomposed and generated aromatic sps.2 Carbon. Combined Figure 9 XPS results show that the oxygen vacancies on this surface are occupied by Ti. 3+ Stable, while aromatic carbon and Ti 4+ Csp is formed through non-covalent interactions 2 (OV)…Ti 4+ Associative compounds stabilize bulk oxygen vacancies and broaden spectral absorption. For example... Figure 11 As shown in the FT-IR spectrum of b, free D100 exhibits typical absorption peaks for -OH, CH, and COC; the Ti(D100)2 hydrogel shows adsorbed water (1630 cm⁻¹). -1 ) and a new hydroxyl-related peak (1397 cm⁻¹) -1 This demonstrates the effect of Ti in the hydrolysis process of D100 and tetrabutyl titanate. 4+ They coordinate with each other to form a glycerate complex hydrogel. Upon calcination at 300℃, the characteristic D100 peak disappears, and a broad C=C vibrational peak (1630 cm⁻¹) appears. -1 The combination of Ti-O-Ti signals further illustrates the thermal decomposition of D100 to generate aromatic Csp. 2 Stable TiO2.

[0086] Tridentate ligand D100 in the construction of polymer Ti(D100) n Hydrogels and mesoporous TiOC materials play a central role in their formation. They are also used in the formation of solid-bound materials. 13 C100 NMR and FT-IR characterization confirmed that D100 exists both on the material surface through physical adsorption and with Ti. 4+ The formation of glycerate complexes provides the necessary support for the formation of mesoporous structures. Figure 10 EPR of TiOC-2 calcined at different temperatures: During low-temperature calcination, unsaturated D100 coordination and an oxygen-rich microenvironment on the surface induce the formation of surface oxygen vacancies (OVs); while saturated D100 coordination and an oxygen-deficient microenvironment inside promote aromatic carbon doping, thereby stabilizing bulk oxygen vacancies and forming Csp. 2 (OV)…Ti 4+ Associative compounds. This precise engineering design endows TiOC-2 with synergistic photothermal and photocatalytic properties.

[0087] Example 11 Study on photothermal response performance

[0088] The photothermal response properties of the mesoporous aromatic carbon-stabilized oxygen vacancy black TiO2 nanomaterial (TiOC-2) prepared in Example 1 were evaluated under environmental conditions (32.9℃, 25% relative humidity).

[0089] When the simulated high intensity of sunlight is 4kWm -2 At times, such as Figure 12As shown in Figure a, the surface temperature of TiOC-2 rapidly increased from room temperature to a peak of 135.0 °C within 50 s; then, with the light source turned off, the temperature rapidly dropped to 48.5 °C within 10 s. In contrast, at a 4kWm... -2 In the following implementation example, the surface temperature rise of TiOC-0 is negligible. Figure 12 b). Additionally, in Figure 12 In step c, within 90 seconds, the surface temperature of TiOC-2 rapidly increased from room temperature to 142.6 ℃. When the light intensity decreased to 1 kWm... -2 At that time, after 90 seconds, the highest surface temperature correspondingly dropped to 54.4 ℃. Furthermore, as... Figure 12 d. During five consecutive on / off irradiation cycles with a 50 s interval, TiOC-2 exhibited stable photothermal behavior, with no significant fluctuations in the highest or lowest temperatures, confirming its strong photothermal conversion stability. Analysis suggests that the uniformly distributed bulk oxygen vacancies and carbon doping in TiOC-2 promote the nonradiative recombination of photogenerated electron-hole pairs, thereby effectively enhancing heat release.

[0090] Example 12 Characterization of aerogel materials from Examples 7-9

[0091] Digital photographs of the aerogels prepared in Examples 7-9 are shown below. Figure 13 As shown, 13a, 13b, and 13c represent SA, SA-TiOC-10, and TiOC@SA-TiOC-5, respectively. Black TiOC-2, which has full-spectrum solar energy absorption and excellent photothermal conversion performance, is integrated into the channel (SA-TiOC) and used as a top coating (TiOC@SA-TiOC) to manufacture an advanced solar photovoltaic evaporator using an SA crosslinking network.

[0092] SEM images of TiOC@SA-TiOC-5 prepared in Example 9 are shown below. Figure 14 As shown, the microporous TiOC-2 particles embedded in the SA fibers roughen the internal pore walls, enhancing capillary-driven water transport and contributing to photocatalytic function. Elemental mapping results show that Ti, O, C, and Ca are uniformly distributed in the material, confirming the successful loading of TiOC-2 particles onto the pore walls and surface of the SA aerogel. Furthermore, TiOC-2, as a top coating, forms a micro-wrinkled surface, effectively increasing specific surface area and light absorption capacity, while simultaneously achieving efficient interfacial evaporation.

[0093] Example 13: Photothermal Evaporation Performance Test of Black TiO2 Nanomaterial-Based Aerogel with Aromatic Carbon Stabilized Oxygen Vacancies

[0094] The aerogels prepared in Examples 7-9 were used for photothermal evaporation tests simulating sunlight (AM1.5), including the following steps:

[0095] An aerogel with dimensions of Φ 20 and h = 2 mm was placed in water in a cylindrical container filled with sufficient water. The apparatus was placed on an electronic balance to record mass changes in real time. Before simulating sunlight exposure, all devices used for water evaporation were kept in darkness for 5 minutes to fully wet the photothermal evaporators and achieve stabilization. The collected data were used to calculate the evaporation rate and evaporation efficiency based on the projected area.

[0096] Depend on Figure 15 Examples 7-9 of this application, along with comparisons of the time-dependent mass change of aerogels under different implementation conditions for photothermal evaporation, confirm that the three aerogels prepared from black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies can exist stably and have good photothermal evaporation effects. Among them, TiOC@SA-TiOC-5 has the best photothermal evaporation effect, reaching 2.61 kgm³. -2 h -1 The highest evaporation rate is higher than that of pure water (0.44 kg / m³). -2 h -1 It increased by 5.9 times compared to SA (0.77 kgm). -2 h -1 The concentration increased by 3.4 times, and significantly increased by 2.05 kgm compared with SA-TiOC-10. -2 h -1 ); Figure 15 c summarizes the water evaporation rate and photothermal conversion efficiency of different photothermal evaporators. TiOC@SA-TiOC-5 has an efficiency of 92.19%, which is better than other photothermal evaporators.

[0097] The photothermal evaporation cycle stability of the aerogel (TiOC@SA-TiOC-5) prepared in Example 9 is as follows: Figure 16 As shown (each cycle is 1 hour), it exhibits good photothermal stability.

[0098] Based on the above characterization and experimental results, the TiOC-2 prepared in Example 1 exhibits excellent photothermal performance, characterized by full-spectrum solar energy absorption, efficient surface charge separation, controllable non-radiative recombination of oxygen vacancies in the bound phase, carbon doping, and multiple scattering effects from the porous network. Sodium alginate aerogel, with its vertical channels, hierarchical pores, and good hydrophilicity, serves as an ideal evaporation framework. Composite TiOC-2 within it and constructing a surface coating can enhance light absorption, capillary water transport, and interfacial evaporation efficiency, achieving highly efficient photothermal evaporation.

[0099] Example 14 Degradation performance test of black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies

[0100] The black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared in Examples 1, 2, and 3 were used for photocatalytic degradation of methylene blue (MB), and Example 1 was used for photocatalytic degradation of rhodamine B, methyl orange, and reduction of Cr(VI), including the following steps:

[0101] In an air atmosphere and in darkness, 0.01 g of the test catalyst and 50 mL of an aqueous solution of pollutants (10 mg / L MB, RhB, MO, and Cr(VI)) were stirred magnetically for 30 min to reach adsorption-desorption equilibrium. Subsequently, a xenon lamp was turned on for photocatalytic degradation, which was continued for 1.5 hours under simulated solar radiation (AM1.5). During the treatment, 2 mL of solution was collected from the suspension every 15 min and immediately filtered through a 0.45 μm membrane filter.

[0102] The concentration of organic dyes was determined by measuring the UV-vis absorption intensity at 664 nm on a UV-vis-NIR spectrometer (LAMBDA950, PerkinElmer). The concentration of Cr(VI) was measured by solvent extraction atomic absorption spectrometry. Degradation efficiency was calculated as (C0-C) / C0, where C and C0 represent the remaining and initial MB concentrations, respectively. The apparent rate constant k of the catalyst was estimated using the pseudo-first-order kinetic equation ln(C0-C) = kt.

[0103] Figure 17 Figure a shows the photocatalytic degradation performance curves of the TiO2 nanomaterials of Examples 1-2 and Comparative Example 1 under neutral conditions over time, confirming that TiOC-2 possesses optimal dark adsorption and photocatalytic degradation performance. This strong adsorption is consistent with the large specific surface area and mesoporous structure observed in TiOC-2 by BET and SEM analyses. Simultaneously, the presence of surface OV may enhance the adsorption of water molecules and subsequent hydroxylation on the catalyst surface, promoting MB interactions and influencing the degradation pathway.

[0104] The cyclic stability of the photocatalytic degradation of MB by the black TiO2 nanomaterial with aromatic carbon-stabilized oxygen vacancies prepared in Example 1 is shown in [reference needed]. Figure 17 b. The results showed that the recovered catalyst could run continuously for 5 times and achieved stable adsorption and a degradation efficiency of over 91.5%.

[0105] Examples 1 and 5-6 illustrate the photocatalytic degradation of MB adsorption, degradation effect, and degradation rate constant of black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies. Figure 18 As shown in the figure, TiOC-2-300℃ exhibits the best photocatalytic degradation performance, which is related to the fact that TiOC-2-300℃ has the most surface oxygen vacancies.

[0106] Example 1 shows that the black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared exhibit a wide range of photocatalytic activities under different pH conditions. Figure 19 Neutral conditions are more conducive to the degradation of MB and RhB, while at pH = 2, the removal rates of MO and Cr(VI) are improved.

[0107] The outdoor performance testing device for the aerogel (TiOC@SA-TiOC-5) prepared in Example 9, and its evaporation rate and photocatalytic activity under different daytime solar intensities are as follows: Figure 20 As shown, vapor rapidly forms on the inclined surface of the device and condenses into clean droplets. With increasing solar intensity throughout the day, the evaporation rate reaches a peak of 2.26 kg / m³ around 13:00. -2 h -1 Meanwhile, the MB degradation rate reached 97.5%, confirming its excellent water purification effect.

[0108] In summary, the black TiO2 nanomaterials with aromatic carbon-stabilized oxygen vacancies exhibit excellent photothermal evaporation rates and photothermal conversion efficiency when treating complex water systems. The fundamental reason lies in the green and resource-efficient calcination removal of glycerol diether D100 during material preparation, which strongly promotes the formation of a mesoporous black TiOC-n highly photoactive material with a high concentration of oxygen vacancies and aromatic carbon doping. Simultaneously, the nanomaterials, due to their large specific surface area, mesoporous structure, and abundant surface oxygen vacancies, can achieve efficient and short-time treatment of organic dyes and high-valence metals, outperforming most existing treatment methods and addressing the complex environmental conditions and diverse pollution sources of real-world wastewater. In other words, the black TiO2 nanomaterial-based aerogel with aromatic carbon-stabilized oxygen vacancies achieves photothermal evaporation and organic matter degradation under natural light, thus efficiently purifying water.

[0109] This invention provides a black titanium dioxide nanomaterial with aromatic carbon stabilizing oxygen vacancies, its preparation method, and its application in water purification. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing black titanium dioxide nanomaterials with aromatic carbon-stabilized oxygen vacancies, characterized in that, Includes the following steps: (1) Dissolve the titanium source in an organic solvent, then add a mixed solution of carbon source and water, sonicate and then carry out a solvothermal reaction to obtain the precursor gel. (2) The precursor gel obtained in step (1) is washed, dried and calcined to obtain the final product.

2. The production method according to claim 1, characterized by, In step (1), the titanium source is an organic titanium source or an inorganic titanium source; and / or, the organic titanium source is any one of tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate, or titanium isopropoxide; and / or, the inorganic titanium source is any one of titanium sulfate, titanium oxysulfate, titanium tetrachloride, or titanium trichloride; and / or, the organic solvent is ethanol; and / or, the carbon source is a glycerol ether diether having the structure shown in formula (I), the structural formula of which is as follows: .

3. The preparation method according to claim 1, characterized in that, In step (1), the mass-to-volume ratio of the titanium source to the organic solvent is 0.2~2 g:5 mL; and / or, the volume ratio of the carbon source to the water is 1~3:1; and / or, the mass-to-volume ratio of the titanium source to the mixed solution is 0.2~2 g:3 mL; and / or, the ultrasonic treatment has a power of 20~40 kHz and a time of 15~30 min; and / or, the solvothermal reaction has a temperature of 90~250 ℃ and a reaction time of 1~10 h.

4. The production method according to claim 1, characterized by, In step (2), the washing is performed using ethanol, and the number of times is 3 to 5; and / or, the drying is performed at a temperature of 60 to 80 °C for 8 to 12 h; and / or, the calcination is performed in an air, nitrogen, or argon atmosphere, with the temperature increased to 300 to 800 °C at a rate of 5 to 8 °C / min, and then calcined for 1 to 10 h.

5. Black titanium dioxide nanomaterials with aromatic carbon-stabilized oxygen vacancies prepared by the preparation method according to any one of claims 1 to 4.

6. A method for preparing a black titanium dioxide-based nanomaterial aerogel, characterized in that, The process includes the following steps: dispersing the black titanium dioxide nanomaterial described in claim 5 with sodium alginate in water to form a precursor mixed solution, freezing and molding it to obtain a hydrogel, and then performing freeze drying, calcium ion crosslinking, solid-liquid separation and drying treatment to obtain the final product.

7. The preparation method according to claim 6, characterized in that, After the freeze-forming process and before the freeze-drying process, an aqueous solution of the black titanium dioxide nanomaterial is coated onto the surface of the hydrogel.

8. The preparation method according to claim 6, characterized in that, The mass ratio of the black titanium dioxide nanomaterial to sodium alginate is 1~3:12; the mass-to-volume ratio of sodium alginate to water is 20~24 mg:1 mL; the freezing is carried out at a temperature of -30 ℃ to -20 ℃ for 12~15 h; the freeze-drying is carried out at a temperature of -50 ℃ to -30 ℃ for 10~15 h and a pressure of -0.5~-0.1 MPa; the calcium ion crosslinking is carried out by immersing the freeze-dried sample in a calcium chloride aqueous solution with a concentration of 1~10wt% for 1~4 h; the drying is carried out at a temperature of 50~80 ℃ for 6~8 h.

9. The preparation method according to claim 7, characterized in that, In the aqueous solution, the concentration of the black titanium dioxide nanomaterial is 1~8 mg / mL.

10. A black titania-based nanomaterial aerogel, characterized in that, It is prepared by the preparation method described in claim 6.

11. A black titania-based nanomaterial aerogel, characterized in that, It is prepared by the preparation method described in claim 7.

12. The application of the black titanium dioxide nanomaterial with aromatic carbon-stabilized oxygen vacancies as described in claim 5, or the black titanium dioxide-based nanomaterial aerogel as described in claim 6 or claim 7, in photothermal evaporation, photocatalytic degradation of water pollutants, and reduction of Cr(VI); preferably, the water pollutants are methylene blue, rhodamine B, and methyl orange.

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