Tungsten oxide modified TiO2 nanorod array as well as preparation method and application thereof

Abstract

The invention provides a tungsten oxide modified TiO2 nanorod array as well as a preparation method and application thereof, and belongs to the technical field of photoelectrocatalysis. The tungsten oxide modified TiO2 nanorod array provided by the invention comprises TiO2 nanorods and sea urchin-shaped WO3 deposited on the surfaces of the TiO2 nanorods, the sea urchin-shaped WO3 comprises a WO3 central core and a WO3 nanometer needle tip which radiates outwards. According to the invention, a heterojunction interface and a built-in electric field are formed between WO3 and TiO2, so that the recombination of photo-induced electron-hole pairs is effectively inhibited, and the charge separation and transmission efficiency is enhanced. Meanwhile, due to the introduction of WO3, the light absorption edge of the composite material is slightly subjected to red shift, and the response of an ultraviolet region is enhanced. The invention also provides a preparation method of the tungsten oxide modified TiO2 nanorod array, and the firm combination and the crystallization quality of the heterojunction are ensured only through a simple hydrothermal and annealing preparation method.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrocatalysis technology, specifically relating to a tungsten oxide-modified TiO2 nanorod array, its preparation method, and its application. Background Technology

[0002] Photoelectrochemical water splitting technology is an effective strategy for converting solar energy into clean hydrogen energy, which is of great significance for achieving sustainable development. Among many semiconductor photocatalysts, titanium dioxide has been widely studied due to its advantages such as good stability, non-toxicity, and low cost. However, pure TiO2 has two major bottleneck problems: first, its wide band gap (about 3.0 eV) leads to the absorption of mainly ultraviolet light, with less than 5% of the solar spectrum being utilized; second, the rapid recombination rate of photogenerated electron-hole pairs severely limits its photoelectric conversion efficiency.

[0003] To overcome these drawbacks, constructing heterojunctions is an effective strategy. By compositing two semiconductors with matched band structures, a built-in electric field can be formed at the interface, promoting the separation and transport of photogenerated carriers and potentially broadening the photoresponse range. WO3, an n-type semiconductor with a narrow band gap (approximately 2.7 eV), matches the band structure of TiO2, making it one of the ideal materials for constructing heterojunctions. However, existing WO3 / TiO2 heterojunction photoanodes suffer from structural instability and cannot maximize the exposure of active sites, leading to reduced photoelectrocatalytic activity. Summary of the Invention

[0004] The purpose of this invention is to provide a tungsten oxide-modified TiO2 nanorod array, its preparation method, and its application. The tungsten oxide-modified TiO2 nanorod array photoanode provided by this invention has excellent structural stability and photoelectrocatalytic activity.

[0005] To achieve the objectives of this invention, the following technical solutions are provided: A tungsten oxide-modified TiO2 nanorod array, comprising a TiO2 nanorod array and urchin-shaped WO3 deposited on the surface of the TiO2 nanorod array; The urchin-shaped WO3 includes a WO3 central core and outwardly radiating WO3 nanoneedles.

[0006] Preferably, the TiO2 nanorods are rutile phase TiO2 nanorods; the diameter of the TiO2 nanorods is 100~1000nm and the length is 0.5~5μm.

[0007] Preferably, the amount of urchin-shaped WO3 deposited accounts for 0.01~2% of the mass of the tungsten oxide modified TiO2 nanorod array.

[0008] Preferably, the average particle size of the WO3 central core in the urchin-like WO3 is 1~10μm; and the average length of the outwardly radiating WO3 nanoneedles is 1~5μm.

[0009] This invention also provides a method for preparing the tungsten oxide-modified TiO2 nanorod array described in the above technical solution, comprising the following steps: TiO2 nanorod arrays were immersed in a tungsten-containing solution and subjected to a first hydrothermal reaction and a first annealing to obtain the tungsten oxide-modified TiO2 nanorod arrays. The tungsten-containing solution included a water-soluble tungsten source, an oxidant, and water. The concentration of the tungsten source in the tungsten-containing solution was 0.01~0.03 mol / L, calculated as tungsten ions.

[0010] Preferably, the temperature of the first hydrothermal reaction is 150~200℃, and the holding time is 4~10h.

[0011] Preferably, the temperature of the first annealing is 80~150℃ and the time is 1~3h.

[0012] Preferably, the method for preparing the TiO2 nanorod array includes the following steps: The substrate was placed in a Ti precursor solution to carry out a second hydrothermal reaction, and after a second annealing, a TiO2 nanorod array was obtained on the surface of the substrate. The Ti precursor solution includes a titanium source and hydrochloric acid.

[0013] Preferably, the temperature of the second hydrothermal reaction is 150~200℃, and the holding time is 4~10h; The second annealing temperature is 300~500℃, and the time is 1~3h.

[0014] The present invention also provides the application of the tungsten oxide modified TiO2 nanorod array described in the above technical solution or the tungsten oxide modified TiO2 nanorod array obtained by the preparation method described in the above technical solution as a photoelectrocatalyst.

[0015] This invention provides a tungsten oxide-modified TiO2 nanorod array, comprising a TiO2 nanorod array and urchin-shaped WO3 deposited on the surface of the TiO2 nanorods; the urchin-shaped WO3 includes a WO3 central core and outwardly radiating WO3 nanoneedles. The urchin-shaped WO3 deposited in this invention increases the specific surface area and improves the wettability of the electrolyte, thereby significantly enhancing the photoelectrocatalytic performance. The type II heterojunction interface and built-in electric field formed between WO3 and TiO2 in this invention effectively suppress the recombination of photogenerated electron-hole pairs, enhancing charge separation and transport efficiency. Simultaneously, the introduction of WO3 causes a redshift in the light absorption edge of the composite material, reducing the band gap from 2.96 eV to 2.85 eV, thus enhancing the response in the ultraviolet region. Results from the embodiments of this invention show that at a potential of 1.23 V vs. RHE, the photocurrent density of the obtained tungsten oxide-modified TiO2 nanorod array reaches 3.05 mA·cm². -2 It is 3 times that of pure TiO2; the photoelectrocatalytic hydrogen production rate reaches 72.12 μmol·cm⁻¹. -2 ·h -1 Compared with pure TiO2, it is improved by about 63%; the carrier lifetime is extended from 1.13ns to 3.49ns, and the charge transfer resistance is reduced from 103.274 Ω to 88.305 Ω; under a bias voltage of 1.4 V vs. RHE, the IPCE value at 385 nm can reach 96.21%, which is much higher than the 49.08% of pure TiO2.

[0016] This invention also provides a method for preparing tungsten oxide-modified TiO2 nanorod arrays. This invention ensures the strong bonding and crystal quality of heterojunctions through a simple hydrothermal and annealing preparation method. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the preparation process of the WO3-modified TiO2 nanorod array of the present invention; Figure 2 These are scanning electron microscope images of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 1. Figure 3 The diffraction patterns of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 1 are shown below. Figure 4The TEM, HRTEM, SAED, and mapping spectra of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 1 are shown. Figure 5 The images show the XPS spectra of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 2.

[0019] Figure 6 These are scanning electron microscope images of the WO3-modified TiO2 nanorod array obtained in Example 2 and the WO3-modified TiO2 nanorod array obtained in Comparative Example 2. Figure 7 The photoluminescence and time-resolved fluorescence spectra of the TiO2 nanorod array obtained in Example 1 and the WO3-modified TiO2 nanorod array obtained in Example 2 are shown. Detailed Implementation

[0020] This invention provides a tungsten oxide modified TiO2 nanorod array, comprising a TiO2 nanorod array and urchin-shaped WO3 deposited on the surface of the TiO2 nanorod array; The urchin-shaped WO3 includes a WO3 central core and outwardly radiating WO3 nanoneedles.

[0021] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0022] In this invention, WO3 particles are also deposited between the TiO2 nanorod arrays.

[0023] In this invention, the method for preparing the TiO2 nanorod array includes the following steps: The substrate was placed in a Ti precursor solution to carry out a second hydrothermal reaction, and after a second annealing, a TiO2 nanorod array was obtained on the surface of the substrate. The Ti precursor solution includes a titanium source and hydrochloric acid.

[0024] In this invention, the substrate is fluorine-doped tin oxide conductive glass (FTO). This invention does not impose specific limitations on the substrate parameters; the substrate is ultrasonically cleaned sequentially with acetone, deionized water, and ethanol before use.

[0025] In this invention, the Ti precursor solution includes a titanium source and hydrochloric acid; the concentration of the hydrochloric acid is 1~6 mol / L; the titanium source includes tetrabutyl titanate; and the concentration of the titanium source in the Ti precursor solution is 0.01~0.5 mol / L.

[0026] In this invention, FTO glass is placed in a reactor containing a precursor solution with the conductive side facing upward and at a 45° angle to the inner wall of the reactor to carry out a second hydrothermal reaction. The temperature of the second hydrothermal reaction is 150~200℃, and in a specific embodiment it can be 170 or 180℃. The holding time is 4~10h, and in a specific embodiment it can be 4 or 8h.

[0027] In this invention, hydrochloric acid with a concentration of 1-6 mol / L is used, which has the following advantages: 1) It inhibits excessively rapid hydrolysis: Tetrabutyl titanate (TBOT) hydrolyzes violently upon contact with water. High concentrations of H2O... + Ions can slow down the hydrolysis rate, making the reaction controllable and conducive to the formation of ordered structures; 2) Structure directing agents: Cl - Ions selectively adsorb onto specific crystal planes of titanium dioxide crystals (usually the {110} plane), inhibiting the growth rate of that plane. Due to the crystal habit of the rutile phase of titanium dioxide, when the growth of the {110} plane is suppressed, the crystal preferentially grows rapidly along the

[001] direction (i.e., the c-axis), thus forming a one-dimensional nanorod / nanowire structure. 3) Providing a reaction environment: a high-temperature, high-pressure acidic aqueous solution environment. The chemical reaction steps in the hydrothermal reaction process of this invention are as follows: (1) TBOT undergoes hydrolysis with water: Ti(OC4H9)4+4H2O→Ti(OH)4+4C4H9OH.

[0028] (2) Condensation and crystallization: The generated Ti(OH)4 is unstable and undergoes dehydration condensation under high temperature and pressure to form the initial nucleus of TiO2; Ti(OH)4 → TiO2 + 2H2O; the primary TiO2 particles react under strong acidic conditions and Cl... - Under the structural guidance of ions, the crystal lattice on the FTO glass substrate is used as a "seed" (epipolar growth), and the lattice preferentially grows along a specific crystallographic direction, eventually growing into a well-crystallized rutile phase TiO2 nanorod array that is perpendicular to the substrate or tilted.

[0029] The present invention places the substrate at an angle to prevent the nanorods or precipitates generated during the reaction from accumulating on the substrate surface due to gravity, thereby ensuring uniform solution convection and enabling the nanorods to "grow" from the substrate surface instead of being "deposited" and covered, ultimately obtaining a uniformly distributed and orderly array.

[0030] That is, the second hydrothermal reaction of the present invention includes the hydrolysis of TBOT and the reaction with Cl in a high temperature, high pressure, acidic environment. - Guided by the ionic structure, the rutile phase titanium dioxide nanorod array undergoes a series of processes including hydrolysis, condensation, and directional crystal growth.

[0031] In this invention, the temperature of the second annealing is 300~500℃, and in specific embodiments it can be 400 or 450℃, for 1~3 hours; the heating rate to the required annealing temperature is 1~5℃ / min; the annealing is carried out in air or an inert atmosphere. During the annealing process of this invention: 1) Removal of organic residues: Butanol that may not have been completely washed away during the hydrothermal reaction, adsorbed trace organic matter, or contaminants from the reaction vessel will be completely oxidized and decomposed into CO2 and H2O at a high temperature of 300~500℃ and volatilized, thereby purifying the sample. 2) Further crystallization and defect repair: Although the hydrothermal products have crystallized, the annealing process can promote atomic rearrangement within the grains, repair defects within the crystals (such as oxygen vacancies), making the crystallization more complete, thereby improving the electron transport performance of the material. 3) Enhanced substrate adhesion: High-temperature annealing enables stronger chemical bonding between TiO2 nanorods and the FTO substrate (possibly through interfacial diffusion), improving the array's mechanical stability and electrical contact performance, and preventing detachment during subsequent device fabrication and use. 4) Adjustment of surface states and hydrophilicity: After annealing, the TiO2 surface adsorbs hydroxyl groups (-OH), becoming more hydrophilic, which is beneficial for contact with the electrolyte in many photoelectrochemical applications (such as photocatalytic water splitting). Furthermore, this invention controls the heating rate to 1~5℃ / min. This slow heating rate ensures uniform heating of the sample, preventing stress, cracking, or detachment within the nanorods or between the nanorods and the substrate due to sudden temperature changes, thus ensuring the integrity of the array structure.

[0032] In this invention, the TiO2 nanorods are rutile phase TiO2 nanorods; the diameter of the TiO2 nanorods is 100~1000nm; and the length is 0.5~5μm.

[0033] In this invention, the deposition amount of the urchin-shaped WO3 accounts for 0.01~2% of the mass of the tungsten oxide modified TiO2 nanorod array, and in specific embodiments it can be 0.05, 0.07, 0.1, 0.3, 0.8, 1.1 or 1.3%.

[0034] In this invention, the average particle size of the WO3 central core in the urchin-shaped WO3 is 1~10μm; the average length of the outwardly radiating WO3 nanoneedle tips is 1~5μm.

[0035] This invention also provides a method for preparing the tungsten oxide-modified TiO2 nanorod array described in the above technical solution, comprising the following steps: TiO2 nanorod arrays were immersed in a tungsten-containing solution and subjected to a first hydrothermal reaction and a first annealing to obtain the tungsten oxide-modified TiO2 nanorod arrays. The tungsten-containing solution included a water-soluble tungsten source, an oxidant, and water. The concentration of the water-soluble tungsten source in the tungsten-containing solution was 0.01~0.03 mol / L, calculated as tungsten ions.

[0036] In this invention, the water-soluble tungsten source can be tungstic acid and / or tungsten salt, specifically sodium tungstate or ammonium tungstate; the concentration of the tungsten source in the tungsten-containing solution is 0.01~0.03 mol / L, and in a specific embodiment, it can be 0.03 mol / L; the oxidant is H2O2, and the concentration of H2O2 is 0.1~5 mol / L. In this invention, H2O2, as an oxidant, participates in the synthesis of the WO3 / TiO2 heterojunction. Specifically, H2O2 is used in conjunction with H2WO4 in the secondary hydrothermal reaction to promote the growth of the WO3 film. Hydrogen peroxide can provide oxygen atoms, which, under appropriate reaction conditions, helps to form the WO3 layer.

[0037] In this invention, the temperature of the first hydrothermal reaction is 150~200℃, and in a specific embodiment it can be 170, 180 or 190℃, and the heat preservation time is 4~10h, and in a specific embodiment it can be 5, 6 or 8h.

[0038] In this invention, the temperature of the first annealing is 80~150℃, and in a specific embodiment it can be 100℃ or 120℃, and the time is 1~3h.

[0039] This invention also provides the application of the tungsten oxide modified TiO2 nanorod array described in the above technical solution or the tungsten oxide modified TiO2 nanorod array obtained by the preparation method described in the above technical solution in the field of photoelectrocatalysis.

[0040] The tungsten oxide-modified TiO2 nanorod array provided by this invention exhibits excellent photoelectrochemical performance, low cost, and good stability, making it suitable as a photoelectrocatalyst for use in the field of photoelectrocatalysis, especially in the preparation of clean energy such as hydrogen.

[0041] To further illustrate the present invention, the tungsten oxide modified TiO2 nanorod array, its preparation method, and its application provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1 according to Figure 1 The flowchart shown illustrates the preparation of WO3-modified TiO2 nanorod arrays. The specific steps are as follows: FTO glass was ultrasonically cleaned sequentially with acetone, deionized water and ethanol to obtain pretreated FTO glass. Tetrabutyl titanate and 6M concentrated hydrochloric acid were stirred and mixed to obtain a precursor solution. The pretreated FTO glass was placed in the reactor containing the precursor solution with the conductive side facing up and at a 45° angle to the inner wall of the reactor. The hydrothermal reaction was carried out at 170°C for 6 hours. After natural cooling, the sample was taken out and rinsed with deionized water. The temperature was increased to 450°C at 2°C / min and annealed in air for 1 hour to obtain a rutile phase TiO2 nanorod array. Rutile TiO2 nanorod arrays were immersed in 0.01M H2WO4 aqueous solution and hydrothermally reacted at 170℃ for 6 hours. After natural cooling, the samples were taken out, rinsed with deionized water, and annealed in air at 100℃ for 1 hour to obtain WO3-modified TiO2 nanorod arrays, denoted as WT-1.

[0043] The resulting photoanode exhibited a photocurrent density of approximately 2.5 mA·cm⁻¹ at 1.23 V vs. RHE. -2 .

[0044] Example 2 FTO glass was ultrasonically cleaned sequentially with acetone, deionized water and ethanol to obtain pretreated FTO glass. Tetrabutyl titanate and 6M concentrated hydrochloric acid were stirred and mixed to obtain a precursor solution. The pretreated FTO glass was placed in the reactor containing the precursor solution with the conductive side facing up and at a 45° angle to the inner wall of the reactor. The hydrothermal reaction was carried out at 170°C for 6 hours. After natural cooling, the sample was taken out and rinsed with deionized water. The temperature was increased to 450°C at 2°C / min and annealed in air for 1 hour to obtain a rutile phase TiO2 nanorod array. Rutile TiO2 nanorod arrays were immersed in 0.02M H2WO4 aqueous solution and hydrothermally reacted at 170℃ for 6 hours. After natural cooling, the samples were taken out, rinsed with deionized water, and annealed in air at 100℃ for 1 hour to obtain WO3-modified TiO2 nanorod arrays, denoted as WT-2.

[0045] The resulting WO3-modified TiO2 nanorod array photoanode exhibited a photocurrent density of 3.05 mA·cm⁻¹ at 1.23 V vs. RHE. -2 The hydrogen production rate was 72.12 μmol / cm³. -2 ·h -1 .

[0046] Example 3 FTO glass was ultrasonically cleaned sequentially with acetone, deionized water and ethanol to obtain pretreated FTO glass. Tetrabutyl titanate and 6M concentrated hydrochloric acid were stirred and mixed to obtain a precursor solution. The pretreated FTO glass was placed in the reactor containing the precursor solution with the conductive side facing up and at a 45° angle to the inner wall of the reactor. The hydrothermal reaction was carried out at 170°C for 6 hours. After natural cooling, the sample was taken out and rinsed with deionized water. The temperature was increased to 450°C at 2°C / min and annealed in air for 1 hour to obtain a rutile phase TiO2 nanorod array. Rutile TiO2 nanorod arrays were immersed in 0.03M H2WO4 aqueous solution and hydrothermally reacted at 170℃ for 6 hours. After natural cooling, the samples were taken out, rinsed with deionized water, and annealed in air at 100℃ for 1 hour to obtain WO3-modified TiO2 nanorod arrays, denoted as WT-3.

[0047] The resulting WO3-modified TiO2 nanorod array photoanode exhibits a photocurrent density of approximately 2.8 mA·cm⁻¹ at 1.23 V vs. RHE. -2 .

[0048] Comparative Example 1 FTO glass was ultrasonically cleaned sequentially with acetone, deionized water and ethanol to obtain pretreated FTO glass. Tetrabutyl titanate and 6M concentrated hydrochloric acid were stirred and mixed to obtain a precursor solution. The pretreated FTO glass was placed in the reactor containing the precursor solution with the conductive side facing up and at a 45° angle to the inner wall of the reactor. The hydrothermal reaction was carried out at 170°C for 6 hours. After natural cooling, the sample was taken out and rinsed with deionized water. The temperature was increased to 450°C at 2°C / min and annealed in air for 1 hour to obtain a rutile phase TiO2 nanorod array.

[0049] The obtained TiO2 nanorod array photoanode exhibits a photocurrent density of 1.03 mA·cm⁻¹ at 1.23 V vs. RHE. -2 The hydrogen production rate was 23.09 μmol / cm³. -2 ·h -1 .

[0050] Comparative Example 2 FTO glass was ultrasonically cleaned sequentially with acetone, deionized water and ethanol to obtain pretreated FTO glass. Tetrabutyl titanate and 6M concentrated hydrochloric acid were stirred and mixed to obtain a precursor solution. The pretreated FTO glass was placed in the reactor containing the precursor solution with the conductive side facing up and at a 45° angle to the inner wall of the reactor. The hydrothermal reaction was carried out at 170°C for 6 hours. After natural cooling, the sample was taken out and rinsed with deionized water. The temperature was increased to 450°C at 2°C / min and annealed in air for 1 hour to obtain a rutile phase TiO2 nanorod array. Rutile TiO2 nanorod arrays were immersed in 0.04M H2WO4 aqueous solution and hydrothermally reacted at 170℃ for 6 hours. After natural cooling, the samples were taken out, rinsed with deionized water, and annealed in air at 100℃ for 1 hour to obtain WO3-modified TiO2 nanorod arrays, denoted as WT-4.

[0051] The resulting WO3-modified TiO2 nanorod array photoanode exhibits a photocurrent density of approximately 2.0 mA·cm⁻¹ at 1.23 V vs. RHE.-2 WO3 has a spherical core.

[0052] Test Example 1 Figure 2 The images show scanning electron microscope (SEM) images of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 1, where (a)-(c) are SEM images of the TiO2 nanorod array, and (d)-(f) are SEM images of the WO3-modified TiO2 nanorod array. Figure 2 It can be seen that the morphological characteristics of the original TiO2 and WO3-modified TiO2 nanorod arrays are compared. For example... Figure 2 As shown in (a)-(c), the original TiO2 exhibits a uniform, dense, and well-aligned array of nanorods, which are mainly grown vertically or slightly tilted under high-density conditions. In contrast, the WO3-modified TiO2 nanorod array ( Figure 2 (d)-(f) show a WO3 structure resembling that of a sea urchin, uniformly distributed on the surface of the TiO2 nanorods. It can be inferred that the growth of WO3 begins with the formation of a spherical core, followed by the appearance of nanospikes on the core surface as the hydrothermal reaction proceeds, ultimately forming... Figure 2 The hierarchical morphology shown in (d) demonstrates how this unique three-dimensional structure effectively increases the specific surface area, thereby enhancing photoelectrocatalytic performance.

[0053] Figure 3 The images show the diffraction patterns of the WO3-modified TiO2 nanorod array obtained in Example 1, where (a) is the XRD diffraction pattern and (b) is the fine XRD diffraction pattern at angles of 36.1-36.7°. Figure 3 The results showed that the diffraction pattern of the original TiO2 was highly matched with that of standard rutile TiO2 (PDF#21-1276), with characteristic peaks located at 27.4°, 36.3°, 41.2°, and 55.1°, corresponding to the (110), (110), and (111) planes, respectively. For the WT sample, additional diffraction features consistent with triclinic WO3 (PDF#33-1387) were also observed. The representative peak at 22.7° was located in the (001) plane of triclinic WO3, confirming successful deposition of WO3 onto the TiO2 nanorods. In the composite, the main diffraction peaks of rutile TiO2 did not show significant changes, indicating that its crystal structure remained largely intact. However, as seen in the high-resolution XRD profile from 36.1° to 36.7° (…),… Figure 3 As shown in b), the position of the TiO2 peak changes slightly after WO3 modification, suggesting that there is a slight interaction at the interface, which affects the local crystal structure.

[0054] Figure 4The images show the TEM, HRTEM, SAED, and mapping spectra of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 1, where (ad) represents the TEM, HRTEM, and SAED spectra of the WO3-modified TiO2 nanorod array, (eg) represents the TEM, HRTEM, and SAED modes of WO3, and (hk) represents the elemental mapping of the WO3-modified TiO2 nanorod array. Figure 4 The results show that, Figure 4 (a) shows lattice fringes with spacings of 0.328 nm and 0.388 nm, corresponding to the (110) plane of rutile TiO2 and the (001) plane of WO3, respectively. Figure 4 (b) shows the selected area electron diffraction (SAED) pattern and its corresponding Fourier transform image. Figure 4 (c) The existence of the (110) and (111) planes of TiO2 was further confirmed, and the measured lattice spacing (0.328 nm) was consistent with the HRTEM observations. Similarly, the SAED pattern also indexed the (001) plane of WO3, and Fourier transform analysis yielded a matching lattice spacing of 0.388 nm. Furthermore, as... Figure 4 As shown in (e), lattice fringes with a spacing of 0.623 nm were observed, corresponding to the (110) plane of WO3. Figure 4 The SAED modes in (f) further confirm the existence of the (100), (001), and (210) planes of WO3. Energy-dispersive X-ray spectroscopy (EDS) elemental mapping ( Figure 4 (h)–(k)) shows that Ti is uniformly distributed within the TiO2 nanorods, while oxygen was detected both inside and on the surface of the nanorods. Notably, W is mainly distributed on the surface of the TiO2 nanorods. These combined results confirm the successful deposition of WO3 films on TiO2 nanorods.

[0055] Figure 5 The images show the XPS spectra of the TiO2 nanorod array and the WO3-modified TiO2 nanorod array obtained in Example 2, where (a)-(d) are the full XPS spectra of the TiO2 photoanode and the WO3-modified TiO2 nanorod array photoanode, respectively; (b) is the W4f spectrum; (c) is the Ti 2p spectrum; and (d) is the O 1s spectrum. Figure 4 The results show that the complete scanning spectrum of the WO3-modified TiO2 nanorod array ( Figure 5 a) Confirmed the coexistence of tungsten, titanium, and oxygen. This was demonstrated in the high-resolution Ti 2p spectrum of pristine TiO2 ( Figure 5 In c), 458.3 eV (Ti 2p) was observed. 3 / 2 ) and 464.1 eV (Ti 2p 1 / 2The characteristic peaks at () are observed. For WO3-modified TiO2 nanorod array samples, the binding energies of these Ti 2p peaks are slightly shifted compared to the original TiO2. In the O 1s region ( Figure 5 d), the original TiO2 exhibits two peaks at 529.7 eV and 531.8 eV, attributed to lattice oxygen and surface hydroxyl groups, respectively. In contrast, the O 1s spectrum of the WO3-modified TiO2 nanorod array shows two peaks at 530.3 eV and 531.6 eV, indicating a change in the chemical environment of oxygen. The W 4f spectrum of the WO3-modified TiO2 nanorod array ( Figure 5 b) Two distinct peaks are observed at 35.5 eV and 37.6 eV, corresponding to W in WO3, respectively. 6+ W4f 7 / 2 and W 4f 5 / 2 Energy levels. The binding energy shifts observed in the Ti 2p and O 1s spectra indicate the presence of electronic interactions between WO3 and TiO2 at the heterojunction interface. Furthermore, the presence of tungsten compounds and the altered chemical states of titanium and oxide further confirm the successful growth of WO3 on the TiO2 nanorod surface. This WO3 layer forms a tight heterojunction interface with the TiO2 nanorods, and the binding energy shifts of Ti 2p and O 1s can be observed using XPS, confirming the electronic interactions at the interface.

[0056] Figure 6 The images show scanning electron microscope (SEM) images of the WO3-modified TiO2 nanorod arrays obtained in Example 2 and Comparative Example 2, where (A)-(C) are SEM images of the WO3-modified TiO2 nanorod array obtained in Example 2, and (D)-(F) are SEM images of the WO3-modified TiO2 nanorod array obtained in Comparative Example 2. Figure 6 As can be seen, the WO3-modified TiO2 nanorod array synthesized in Example 2 exhibits a sea urchin-like WO3 structure, uniformly distributed on the surface of the TiO2 nanorods. Figures (D)-(F) show the WO3-modified TiO2 nanorod array synthesized in Comparative Example 2, where the WO3 forms a spherical core.

[0057] Figure 7 The photoluminescence and time-resolved fluorescence spectra of the TiO2 nanorod arrays obtained in Example 1 and the WO3-modified TiO2 nanorod arrays obtained in Example 2 are shown. (a) Photoluminescence emission spectrum of TiO2; (b) Photoluminescence emission spectrum of the WO3-modified TiO2 nanorod array; (c) Time-resolved fluorescence spectrum of the samples. PL results show that the fluorescence intensity of the WO3-modified TiO2 nanorod array is significantly enhanced compared to TiO2. Figure 7a). This can be attributed to the improved photogenerated carrier capture efficiency after modification, which increases carrier concentration and thus enhances recombination probability, resulting in higher fluorescence intensity. The decay kinetics of photogenerated carrier lifetime were investigated using time-resolved photoluminescence (TR-PL) spectroscopy. The average photogenerated carrier lifetimes of TiO2 and WO3-modified TiO2 nanorod array photoanodes were 1.13 ns and 3.49 ns, respectively. Figure 7 b). The extended carrier lifetime observed in the WO3-modified TiO2 nanorod array indicates that photogenerated carriers have more time to participate in the photoelectrocatalytic reaction before recombination, confirming that the robust bonding of the constructed heterojunction effectively promotes charge separation and transport.

[0058] Under photocurrent, the strong bonding of heterojunctions promotes the efficient separation and transport of photogenerated carriers. When the heterojunction is well bonded, an ideal band structure is formed between the two semiconductor materials, allowing the electrons and holes generated by photoexcitation to separate rapidly, and the carriers have a longer lifetime, enabling them to participate more effectively in the water oxidation reaction, thus generating a larger photocurrent. Tests show that the lifetime of photogenerated carriers is significantly increased after WO3 is loaded on TiO2 to form a heterojunction, indicating the stability of this heterojunction structure and its ability to generate carriers with a long lifetime.

[0059] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A tungsten oxide-modified TiO2 nanorod array, characterized in that, Includes TiO2 nanorod arrays and urchin-like WO3 deposited on the surface of the TiO2 nanorod arrays; The urchin-shaped WO3 includes a WO3 central core and outwardly radiating WO3 nanoneedles.

2. The tungsten oxide-modified TiO2 nanorod array according to claim 1, characterized in that, The TiO2 nanorods are rutile phase TiO2 nanorods; the diameter of the TiO2 nanorods is 100~1000nm and the length is 0.5~5μm.

3. The tungsten oxide-modified TiO2 nanorod array according to claim 1, characterized in that, The amount of urchin-shaped WO3 deposited accounts for 0.01~2% of the mass of the tungsten oxide modified TiO2 nanorod array.

4. The tungsten oxide-modified TiO2 nanorod array according to claim 1, characterized in that, The average particle size of the WO3 central core in the urchin-shaped WO3 is 1~10μm; the average length of the outwardly radiating WO3 nanoneedles is 1~5μm.

5. The method for preparing the tungsten oxide-modified TiO2 nanorod array according to any one of claims 1 to 4, characterized in that, Includes the following steps: TiO2 nanorod arrays were immersed in a tungsten-containing solution to undergo a first hydrothermal reaction and a first annealing to obtain the tungsten oxide-modified TiO2 nanorod arrays; the tungsten-containing solution included a water-soluble tungsten source, an oxidant, and water; The concentration of the tungsten source in the tungsten-containing solution is 0.01~0.03 mol / L, calculated as tungsten ions.

6. The preparation method according to claim 5, characterized in that, The temperature of the first hydrothermal reaction is 150~200℃, and the holding time is 4~10h.

7. The preparation method according to claim 5, characterized in that, The temperature of the first annealing is 80~150℃, and the time is 1~3h.

8. The preparation method according to claim 5, characterized in that, The method for preparing the TiO2 nanorod array includes the following steps: The substrate was placed in a Ti precursor solution to carry out a second hydrothermal reaction, and after a second annealing, a TiO2 nanorod array was obtained on the surface of the substrate. The Ti precursor solution includes a titanium source and hydrochloric acid.

9. The preparation method according to claim 8, characterized in that, The temperature of the second hydrothermal reaction is 150~200℃, and the time is 4~10h; The second annealing temperature is 300~500℃, and the holding time is 1~3h.

10. The application of the tungsten oxide modified TiO2 nanorod array according to any one of claims 1 to 4 or the tungsten oxide modified TiO2 nanorod array obtained by the preparation method according to any one of claims 5 to 9 as a photoelectrocatalyst.

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