Gold-tiO2 composite nanomaterial, preparation method thereof and photocatalytic degradation application thereof

Abstract

The application discloses a gold-TiO2 composite nanometer material and a preparation method and photocatalytic degradation application thereof. The preparation method comprises the following steps: sputtering Ti and Au on a substrate in sequence by using a magnetron sputtering to obtain a Ti-Au film; and annealing the Ti-Au film to obtain the gold-TiO2 composite nanometer material, wherein the annealing temperature is 300-800 DEG C. The preparation method is simple and efficient, and the prepared gold-TiO2 composite nanometer material has excellent photoelectric degradation performance, good stability and strong absorption effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectric materials, and particularly relates to a gold-TiO2 composite nanomaterial, a preparation method thereof and photocatalytic degradation application. BACKGROUND

[0002] Most of the antibiotics used in production and life are not absorbed and metabolized, but remain in aquaculture water and wastewater and flow into the water environment. Due to the poor natural degradation performance of antibiotics, and the lack of related devices for treating water bodies containing antibiotics at present, there are a large number of antibiotic pollutants in the water body. In addition to the harm caused by being directly consumed by humans and animals, the residues of antibiotics in the water body can directly harm plants such as blue-green algae. In view of the various adverse effects of antibiotics on humans and various organisms, it is urgent to explore a rapid degradation technology for antibiotics in water bodies.

[0003] The degradation of antibiotics refers to the process that the carbon content of antibiotics is continuously reduced through chemical reactions, and finally only harmless small molecules are contained. Under light, plasmonic gold nanomaterials can generate hot electrons and hot holes with catalytic properties. However, although gold nanomaterials can generate a large number of hot carriers, they are prone to recombination, resulting in only a small number of hot carriers participating in the catalytic reaction, so that the catalytic degradation performance of directly using plasmonic nanostructures is difficult to meet the actual demand. The hot electrons generated by plasmonic nanostructures can cross the Schottky barrier between the metal and the semiconductor conduction band and transfer to the semiconductor, avoiding the recombination of hot electrons and hot holes, and prolonging the lifetime of hot carriers and improving the catalytic performance of hot carriers.

[0004] The patent application with the publication number CN117282453A discloses a preparation method of Au-N co-doped TiO2 nanotube and a photoelectric catalytic water purification system, and relates to the technical field of TiO2 photoelectric catalysis. The preparation method comprises the following steps: a pretreatment step; an electrolyte preparation step; an anodic oxidation step: electrolytic oxidation is performed on a titanium sheet; the titanium sheet after electrolytic oxidation is washed and dried to obtain a TiO2 electrode; an Au-TiO2 electrode preparation step: the TiO2 electrode is immersed in an AuCl3·HCl·4H2O solution with different concentrations; after vertical irradiation with a high-pressure mercury lamp for a preset time, washing and drying are performed to obtain an Au-TiO2 electrode; an Au-TiO2 electrode nitrogen-doping modification step: the Au-TiO2 electrode prepared in the Au-TiO2 electrode preparation step is subjected to nitrogen-doping modification by using a plasma reaction system to obtain an Au-N-TiO2 electrode; and the Au-N-TiO2 electrode is calcined to obtain an Au-N-TiO2 nanotube electrode. However, the method provided by the patent has complicated steps, and the stability and absorption effect need to be further improved.

[0005] TiO2 has the advantages of strong chemical stability and low cost, and is widely used in coupling plasmonic nanostructures to improve catalytic effect. For example, a thin transparent TiO2 semiconductor layer is placed between the plasmonic nanostructure and the metal substrate, and the absorption effect and catalytic effect of the composite material are significantly improved, because the Fabry-Perot cavity formed by the nanoparticles, the highly reflective metal substrate and the transparent semiconductor as the spacer makes the nanomaterial have multiple resonance peaks. The appearance of the resonance peak causes the efficiency of hot carrier generation to be significantly improved, and the close contact between the TiO2 semiconductor layer and the plasmonic nanostructure promotes the transfer of hot carriers, so that the material has excellent photoelectrocatalytic performance. However, at present, basically all plasmonic / semiconductor composite structures have the disadvantages of complicated steps, high cost and complex operation. Therefore, it is of great significance to simply, conveniently and quickly couple doped TiO2 in gold nanomaterials to synthesize materials with strong absorption effect and excellent photoelectric effect. SUMMARY

[0006] The application provides a simple preparation method of gold-TiO2 composite nanomaterial and application of the gold-TiO2 composite nanomaterial in photocatalytic degradation, and the preparation method is simple and efficient, and the prepared gold-TiO2 composite nanomaterial has excellent photoelectrocatalytic performance, good stability and strong absorption effect.

[0007] The application provides a preparation method of gold-TiO2 composite nanomaterial, which comprises the following steps:

[0008] (1) Ti and Au are sputtered on a substrate in sequence by using a magnetron sputtering to obtain a Ti-Au film;

[0009] (2) the Ti-Au film in step (1) is annealed to obtain the gold-TiO2 composite nanomaterial, wherein the annealing temperature is 300-800 ℃.

[0010] The application promotes the strong coupling and high mixing level of Au and TiO2 by the annealing process, increases the interface quantity of the gold-TiO2 composite nanomaterial, and promotes the transfer of hot electrons to TiO2. Controlling the annealing temperature is beneficial to the remodeling of the surface morphology of the material, so that the composite nanomaterial with a suitable contact angle is obtained. Under high-temperature sufficient annealing, the synthesized material is more hydrophilic, and is more conducive to the transfer of hot carriers to the electrolyte solution for catalytic reaction.

[0011] Preferably, the annealing time is 1-10 h. The appropriate annealing time can make the surface morphology remodeling more sufficient, and avoid the remodeling surface morphology from being damaged.

[0012] Preferably, the annealing temperature is 300-800 DEG C. By further controlling the annealing temperature, the pore of the gold-TiO2 composite nanomaterial is further increased, and the particle size is further increased, so that the light absorption effect is enhanced, more hot electrons are generated, and the catalytic reaction is more effective.

[0013] Preferably, the thickness of the Ti layer deposited on the substrate is 20-80 nm, and the thickness of the Au layer is 50-500 nm.

[0014] Preferably, the substrate is glass, and the glass is cleaned by a plasma cleaner before magnetron sputtering.

[0015] Further preferably, the cleaning time of the plasma cleaner is 1-10 min.

[0016] In another aspect, the application also provides a gold-TiO2 composite nanomaterial prepared by the preparation method of the gold-TiO2 composite nanomaterial.

[0017] Preferably, the particle size of the gold-TiO2 composite nanomaterial is 30-60 nm.

[0018] Preferably, the content ratio of Ti element and Au element of the gold-TiO2 composite nanomaterial is 0.5-10% and 90-99.5%, respectively.

[0019] In another aspect, the application also provides a gold-TiO2 composite nanomaterial for use in photocatalytic degradation of antibiotics.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] The application makes Au and TiO2 better fuse by annealing the Ti-Au film obtained by magnetron sputtering, promotes the transfer of hot electrons to TiO2, prolongs the optical path of the material by doping TiO2, and makes the light in the material multiple reflection, absorption and transmission, greatly enhancing the light absorption effect and hot electron generation performance of the material.

[0022] The application controls the annealing temperature, so that the prepared gold-TiO2 composite nanomaterial has a high contact angle and high hydrophilicity, and the generated hot electrons are more easily transferred to the electrolyte solution for catalytic reaction. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1This is a scanning electron microscope image of the gold-TiO2 composite nanomaterial prepared in Example 1, a scanning electron microscope image of the gold-TiO2 composite nanomaterial magnified 20,000 times, wherein the partial magnified image is a scanning electron microscope image of the gold-TiO2 composite nanomaterial magnified 50,000 times;

[0024] Figure 2 This is a scanning electron microscope image of the gold-TiO2 composite nanomaterial prepared in Example 2, a scanning electron microscope image of the gold-TiO2 composite nanomaterial magnified 20,000 times, wherein the partial magnified image is a scanning electron microscope image magnified 50,000 times, Figure 2 The annealing temperature of a preparation is 300℃, Figure 2 b is 500℃, Figure 2 c is 700℃;

[0025] Figure 3 This is the diffuse reflectance ultraviolet absorption spectrum of the gold-TiO2 composite nanomaterial prepared in Example 2;

[0026] Figure 4 This is the contact angle diagram of the gold-TiO2 composite nanomaterial prepared in Example 2. Figure 4 The annealing temperature of a preparation is 300℃, Figure 4 b is 500℃, Figure 4 c is 700℃;

[0027] Figure 5 This is the linear sweep voltammogram of the gold-TiO2 composite nanomaterial prepared in Example 3;

[0028] Figure 6 This is the photoelectric conversion efficiency curve of the gold-TiO2 composite nanomaterial prepared in Example 3;

[0029] Figure 7 This is the photocurrent-time curve of the gold-TiO2 composite nanomaterial prepared in Example 3;

[0030] Figure 8 The C of the gold-TiO2 composite nanomaterial prepared in Example 4 during the degradation of different antibiotics t / C0 changes, Figure 8 a is C that degrades malachite green t / C0 changes, Figure 8 b is C that degrades levofloxacin t / C0 changes. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] Example 1

[0033] Preparation of gold-TiO2 composite nanomaterials

[0034] (1) Preparation of Ti-Au film: Ti (50 nm) and Au (150 nm) were sputtered on glass in sequence by a magnetron sputtering system to prepare a Ti-Au film.

[0035] (2) Preparation of gold-TiO2 composite nanomaterials: The Ti-Au film prepared in step (1) was annealed in a muffle furnace to prepare gold-TiO2 composite nanomaterials, wherein the annealing temperature was 700 ℃ and the annealing time was 4 h.

[0036] (3) The surface morphology of the prepared gold-TiO2 composite nanomaterials was tested by a scanning electron microscope, and the results are shown in Figure 1 . The size of the synthesized gold-TiO2 nanoparticles was 42.66 ± 6.68 nm.

[0037] Example 2

[0038] Different annealing temperatures for preparation of gold-TiO2 composite nanomaterials

[0039] (1) The process and conditions were the same as described in Example 1 above, except that the Ti-Au film was annealed in a muffle furnace at temperatures of 300 ℃, 500 ℃ and 700 ℃, respectively.

[0040] (2) The scanning electron microscope images of the gold-TiO2 composite nanomaterials prepared in Example 2 and their partial magnified images were tested, and the results are shown in Figure 2 . When the annealing temperature was 300 ℃, the surface of the gold-TiO2 composite nanomaterials was relatively flat and had not yet formed particles, and there were multiple small-sized pores as shown in Figure 2 (a). When the annealing temperature was 500 ℃, the surface of the material formed more pores and a large number of small-sized particles as shown in Figure 2 (b). When the annealing temperature was 700 ℃, the surface of the material formed particles with a size of 42.66 ± 6.68 nm as shown in Figure 2 (c).

[0041] (3) The diffuse reflectance ultraviolet absorption spectrum of the gold-TiO2 composite nanomaterials prepared in Example 2 was tested, and the results are shown in Figure 3 . The light absorption rate of the gold-TiO2 composite nanomaterials in the range of 500-700 nm was higher than 80%, and the light absorption rate of the gold-TiO2 composite nanomaterials at 300 nm was higher than 50%.

[0042] (4) The contact angle of the gold-TiO2 composite nanomaterials prepared in Example 2 was tested, and the results are shown in Figure 4The contact angle decreases obviously with the increase of annealing temperature, which proves that the synthesized material is more hydrophilic and more conducive to the transfer of hot carriers to the electrolyte solution for catalytic reaction at high temperature.

[0043] Application Example 1

[0044] Evaluation of the photoelectric performance of gold-TiO2 composite nanomaterials

[0045] (1) The gold-TiO2 composite nanomaterial prepared as described in Example 2 was used for photoelectric performance test. The gold-TiO2 composite nanomaterial was used as the working electrode, the electrode area was 1 cm x 1 cm, Ag / AgCl was the reference electrode, platinum wire was the counter electrode, the photoelectric test reaction cell was a cuboid quartz reactor (2.3 cm x 2.3 cm x 1.7 cm), 0.5 M Na2SO4 was the electrolyte solution, the scanning window was 0.2-1.6 V, the applied voltage was 1.4 V, and the visible light source was a Philips 300 W xenon lamp with a UV filter (λ>400 nm).

[0046] (2) The linear sweep voltammogram of the gold-TiO2 composite nanomaterial prepared in Example 3 was tested, and the results are shown in Figure 5 . The photocurrent increases with the increase of voltage, and the gold-TiO2 composite nanomaterial annealed at 700°C is the most obvious. Under a voltage of 0.6-1.4 V, the photocurrent intensity increases with the increase of annealing temperature. Compared with TiO2, the photocurrent of the gold-TiO2 composite nanomaterial annealed at 700°C at 1.4 V is 30 times that of TiO2.

[0047] (3) The IPCE curve of the gold-TiO2 composite nanomaterial used in this application example was tested, and the results are shown in Figure 6 . Under 520 nm wavelength light, the IPCE of the gold-TiO2 composite nanomaterial annealed at 300, 500, and 700°C and TiO2 is 0.16, 0.27, 0.34, and 0.013%, respectively. The IPCE of the gold-TiO2 composite nanomaterial annealed at 700°C is 26 times that of TiO2. Under 365 nm light, compared with TiO2, the light absorption of the material is not significantly improved, but the IPCE is significantly improved by 2.5 times.

[0048] (4) The photocurrent-time curve of the gold-TiO2 composite nanomaterial used in this application example was tested, and the results are shown in Figure 7 . After 8 h of photoelectric water splitting experiment, the photocurrent is still very stable, which proves that the gold-TiO2 composite nanomaterial has very good stability and can be applied to long-term photoelectric catalytic reaction.

[0049] Application Example 2

[0050] Performance evaluation of gold-TiO2 composite nanomaterials for photoelectrocatalytic degradation of antibiotics

[0051] (1) The gold-TiO2 composite nanomaterials prepared in Example 1 were used for performance evaluation of photoelectrocatalytic degradation of malachite green and levofloxacin.

[0052] (2) Malachite green and levofloxacin were used as target pollutants, and the initial concentrations of the target pollutants were 1×10 -4 mol / L and 1×10 -5 mol / L during the experiment. Visible light with λ>400 nm was used as the light source, the gold-TiO2 composite nanomaterials were used as the working electrode, the electrode area was 1 cm×1 cm, Ag / AgCl was used as the reference electrode, platinum wire was used as the counter electrode, the photoelectric test reaction cell was a cuboid quartz reactor (2.3 cm×2.3 cm×1.7 cm), and the electrolyte solution was 0.1 M Na2SO4. Before the reaction started, the electrode was immersed in the solution containing the pollutants for dark adsorption treatment (30 min), then the light source was started, a voltage of 1.4 V was applied, and after a certain period of time, 200 μL of sample was taken, the absorbance of malachite green and levofloxacin was measured at 617 nm and 293 nm, respectively, by using a UV spectrophotometer, and the degradation degree of malachite green and levofloxacin was determined. The degradation rate of the pollutants was calculated by the formula η=(1-C t / C0)×100%, wherein η was the degradation rate of the target after t min of illumination, C0was the concentration of the pollutants at the adsorption equilibrium, and C t was the concentration of the pollutants after t min of degradation reaction.

[0053] (3) As shown in Figure 8 a and Figure 8 b, malachite green and levofloxacin with concentrations of 1×10 -4 mol / L and 1×10 -5 mol / L could be basically completely degraded within 100 min, which proved that the gold-TiO2 composite nanomaterials could be used as a photoelectrocatalytic electrode for degradation of malachite green and levofloxacin in polluted water, and could be expected to be applied to rapid degradation of other pollutants.

[0054] The above examples are only used to illustrate the technical solutions described in the present application and do not limit the present application; therefore, although the present application has been described in detail with reference to the above-described various embodiments, those skilled in the art should understand that the present application can still be modified or replaced equivalently; and all technical solutions and improvements that do not deviate from the spirit and scope of the present application should be covered within the scope of the claims of the present application.

Claims

1. A method for preparing a gold-TiO2 composite nanomaterial, characterized in that: include: (1) Ti and Au were sequentially sputtered on the substrate using magnetron sputtering to obtain a Ti-Au film; (2) annealing the Ti-Au film obtained in step (1) to obtain a gold-TiO2 composite nanomaterial, wherein the annealing temperature is 500-800°C; The annealing time is 1-10 h; The thickness of the Ti layer deposited on the substrate is 20-80 nm, and the thickness of the Au layer is 50-500 nm.

2. The method for preparing the gold-TiO2 composite nanomaterial according to claim 1, wherein: The substrate is glass, and before magnetron sputtering, a plasma cleaner is used to clean the glass.

3. A gold-TiO2 composite nanomaterial, characterized in that: The gold-TiO2 composite nanomaterial is prepared according to the preparation method of the gold-TiO2 composite nanomaterial according to any one of claims 1-2.

4. The gold-TiO2 composite nanomaterial according to claim 3, characterized in that The particle size of the gold-TiO2 composite nanomaterial is 30-60 nm.

5. Use of the gold-TiO2 composite nanomaterial according to claim 3 or 4 in the photoelectrocatalytic degradation of malachite green and levofloxacin.

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