Preparation method and application of a trivalent rhodium-doped titanium dioxide photocatalyst

Abstract

The application belongs to the field of energy materials and photocatalytic hydrogen production, and provides a preparation method and application of a trivalent rhodium-doped titanium dioxide photocatalyst. The method comprises the following steps: (1) immerging rutile titanium dioxide powder in a rhodium salt solution, ultrasonic dispersion, stirring in a 50-90 DEG C water bath until uniform, continuing to stir until the solvent is evaporated, and obtaining a precursor powder; (2) placing the precursor powder obtained in step (1) in a quartz tube, and performing calcination under an air atmosphere rich in water vapor, and obtaining the trivalent rhodium-doped titanium dioxide photocatalyst. The preparation process is simple, the generation of quadrivalent rhodium ions which are not conducive to photocatalytic hydrogen production reaction can be inhibited, and the trivalent rhodium-doped titanium dioxide photocatalyst is obtained. The visible light photocatalytic hydrogen production activity of the obtained rhodium-doped titanium dioxide photocatalyst is much higher than that of a photocatalyst synthesized by a traditional solid phase method, and the rhodium-doped titanium dioxide photocatalyst has good stability.

Description

Technical Field

[0001] This invention belongs to the field of energy materials and photocatalytic hydrogen production technology, specifically relating to a method for preparing and applying a titanium dioxide photocatalyst rich in trivalent rhodium doped with trivalent rhodium. By controlling the valence state of rhodium with the aid of water vapor, i.e., suppressing the formation of tetravalent rhodium, a titanium dioxide photocatalyst rich in trivalent rhodium doped with trivalent rhodium is formed. Background Technology

[0002] Titanium dioxide (TiO2) is a transition metal oxide with good stability at room temperature, does not readily react with other compounds, and possesses advantages such as non-toxicity and good biocompatibility. Due to its high photostability, non-toxicity, and abundance, TiO2 is the most widely used and studied semiconductor photocatalyst to date (J. Am. Chem. Soc. 2011, 133, 13272-13275). In 1972, Fujishima and Honda discovered that water on a TiO2 electrode could be photocatalytically decomposed to produce hydrogen. Since then, photocatalytic reactions based on semiconductor powder systems have been extensively studied (Nature, 1972, 238, 37-38). Because TiO2 has a relatively wide band gap (3.0 eV), it is only photoresponsive to ultraviolet light, resulting in relatively low solar energy utilization efficiency. Therefore, extending the absorption band gap of TiO2 into the visible region is of significant research importance.

[0003] Doping TiO2 with transition metals is one of the effective strategies to improve its visible light response. Among them, rhodium (Rh)-doped TiO2 is a representative visible light-responsive photocatalyst. Tetravalent rhodium ions (Rh...) 4+ The introduction of deep-level trap states located in the middle of the band gap in TiO2 can serve as effective recombination centers for photogenerated electrons and holes, thereby reducing photocatalytic efficiency. Conversely, trivalent rhodium ions (Rh) introduce deep-level trap states in the middle of the band gap. 3+ Impurity energy levels are formed near the valence band apex of the TiO2 band gap. These energy levels can effectively capture photogenerated holes, promote the migration of electrons to the catalyst surface and their participation in the reaction, thus Rh 3+ It is a more ideal valence state for doped ions.

[0004] In order to suppress Rh 4+ Co-doping strategies have been widely adopted for ion generation. In 2007, Kudo proposed Rh... 3+ / Sb 5+ Co-doped rutile TiO2 was used for visible light-driven photocatalytic oxygen production. Studies have shown that Sb... 5+ The presence of ions can suppress Rh through charge compensation. 4+The formation of ions enables photocatalytic oxygen evolution activity that is 11.1 times higher than that of Rh-doped TiO2 under visible light irradiation (J. Phys. Chem. C., 2007, 111, 10621-10627). However, Sb 5+ The introduction of doping can mitigate some defects, but the impurities introduced by doping can still act as electron-hole recombination centers. Furthermore, co-doping may introduce additional ions, thereby creating other defects that are detrimental to the transport of photogenerated carriers.

[0005] On the other hand, in 2021, Ma Guijun et al. prepared Rh-doped TiO2 photocatalysts via impregnation-calcination and found that Rh-doped rutile TiO2 exhibited superior photocatalytic hydrogen production activity compared to anatase TiO2 (Appl. Phys. Lett., 2021, 119, 213901). However, current methods for preparing Rh-doped photocatalysts are primarily high-temperature solid-state methods, during which high temperatures can cause Rh to... 3+ Change to Rh 4+ , and Rh 4+ It is a charge recombination center, which is not conducive to photocatalytic hydrogen production.

[0006] Therefore, it is necessary to develop a method that can suppress Rh without introducing additional elements. 4+ The generated TiO2 photocatalyst has significant research implications. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing and applying a rhodium-doped titanium dioxide photocatalyst. This invention employs a water vapor-assisted solid-state method, using water vapor to help regulate the valence state of rhodium and suppress the formation of tetravalent rhodium, thus forming a rhodium-doped rutile titanium dioxide photocatalyst and solving the problems mentioned in the background section.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: The first aspect of this invention provides a method for preparing a rhodium-doped titanium dioxide photocatalyst, the method comprising the following steps: (1) Immerse rutile titanium dioxide powder in rhodium salt solution, disperse ultrasonically, stir in a water bath at 50~90 ℃ until uniform, and continue stirring until the solvent evaporates to obtain precursor powder; (2) The precursor powder obtained in step (1) is placed in a quartz tube and calcined in an air atmosphere rich in water vapor to obtain the trivalent rhodium-doped titanium dioxide photocatalyst.

[0009] In the above technical solution, further, in step (1), the rhodium salt includes any one of rhodium chloride, rhodium nitrate, rhodium acetate, and ammonium rhodium chloride.

[0010] In the above technical solution, further, in step (1), the molar ratio of rhodium to titanium is 0.0005~0.03:1.

[0011] In the above technical solution, further, in step (2), the calcination temperature is 500~1000 ℃ and the calcination time is 1~40 h.

[0012] In the above technical solution, further, in step (2), the heating rate during calcination is 2~6 ℃ min. -1 .

[0013] In the above technical solution, further, in step (2), during the calcination process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube so that the precursor powder is calcined in an environment rich in water vapor.

[0014] In another aspect, the present invention provides the application of the trivalent rhodium-doped titanium dioxide photocatalyst prepared by the above-described method in photocatalytic reactions.

[0015] In the above technical solution, the photocatalytic reaction is a photocatalytic water splitting reaction to produce hydrogen, specifically: the trivalent rhodium-doped titanium dioxide photocatalyst is dispersed in an aqueous solution containing a hole sacrificial agent and a co-catalyst, and the hydrogen production reaction is carried out under light irradiation.

[0016] The beneficial effects of this invention are: 1. This invention solves the problem of Rh at high temperatures. 3+ Easily oxidized to Rh 4+ This addresses the problem by reducing charge recombination centers and increasing the carrier migration rate.

[0017] 2. This invention synthesizes Rh-doped rutile TiO2 material using a water vapor-assisted solid-state method, thereby controlling the TiO2 doping process, suppressing the formation of tetravalent rhodium, and promoting the formation of trivalent rhodium.

[0018] 3. It does not introduce additional dopant ions, thus avoiding other defects that may be introduced by co-doping, which is beneficial to the transport of photogenerated carriers.

[0019] 4. The Rh-doped titanium dioxide photocatalyst synthesized by the water vapor-assisted solid-state method has better photocatalytic hydrogen production activity than the photocatalyst synthesized by the traditional solid-state method.

[0020] 5. The preparation process of this invention is simple and the cost is low. Attached Figure Description

[0021] Figure 1 A schematic diagram of the preparation of rhodium-doped titanium dioxide photocatalyst powder by a water vapor-assisted solid-state method; Figure 2 The XRD patterns are of the samples prepared in Example 1 and Comparative Example 1. Figure 3 Rh 3d XPS spectra of the samples prepared in Example 1 and Comparative Example 1; Figure 4 The photocatalytic hydrogen production activity of the samples prepared in Example 1 and Comparative Example 1 dispersed in 80 mL of a solution containing 0.5 M ascorbic acid was measured. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments. The materials involved in the present invention are not limited to those described in the following embodiments. Furthermore, the embodiments only provide some conditions for achieving this objective, but do not imply that these conditions must be met to achieve this objective.

[0023] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0024] Example 1 The photocatalyst was prepared according to the following steps: Step 1: Weigh 0.0033 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace using a water-assisted solid-state method. The calcine temperature is 500 ℃, the calcine time is 1 h, and the heating rate is 2 ℃ min. -1 The water vapor-assisted solid-state method specifically includes: (e.g.) Figure 1 As shown, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into a quartz tube, so that the precursor powder is calcined in an environment rich in water vapor.

[0025] Example 2 Step 1: Weigh 0.00165 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0026] Example 3 Step 1: Weigh 0.00495 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into a quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0027] Example 4 Step 1: Weigh 0.0989 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0028] Results and Discussion: The difference between Examples 1-4 lies in the modulation of the molar ratio of Rh to Ti; all other conditions remain the same. It can be seen that by modulating the molar ratio of Rh to Ti, Rh-doped titanium dioxide photocatalysts can be prepared via a water vapor-assisted solid-state method.

[0029] Example 5 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 800 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0030] Example 6 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 900 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0031] Example 7 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 1000 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0032] Results and Discussion: The only difference between Examples 1 and Examples 5-7 is the change in the calcination temperature of the tubular furnace. All other conditions are the same. It can be seen that by changing the calcination temperature of the tubular furnace, Rh-doped titanium dioxide photocatalysts can be prepared by the water vapor-assisted solid-state method.

[0033] Example 8 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 8 h with a heating rate of 2 ℃ / min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an air atmosphere rich in water vapor.

[0034] Example 9 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 10 h with a heating rate of 2 ℃ / min. -1During the roasting process, air is introduced into a device containing an aqueous solution, which generates bubbles. The bubbles carry water vapor into the tube furnace, allowing the precursor powder to be roasted in an air atmosphere rich in water vapor.

[0035] Example 10 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 40 h with a heating rate of 2 ℃ / min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0036] Results and Discussion: The difference between Examples 1 and 8-10 lies in the calcination time; all other conditions are the same. It can be seen that by changing the calcination time in the tubular furnace, Rh-doped titanium dioxide photocatalysts can be prepared via the water-vapor assisted solid-state method.

[0037] Example 11 Step 1: Weigh 0.00330 g of Rh(NO3)3 and 1.0000 g of TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube to roast the precursor powder.

[0038] Example 12 Step 1: Weigh 0.00330 g Rh2(CH3COO)4 and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 1 hour with a heating rate of 2 ℃ / min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0039] Example 13 Step 1: Weigh 0.00330 g (NH4)3[RhCl6] and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: Place the precursor powder obtained in Step 1 into a quartz tube and calcine it in a tube furnace at a calcine temperature of 500 ℃ for 1 h with a heating rate of 2 ℃ min. -1 During the roasting process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube, so that the precursor powder is roasted in an environment rich in water vapor.

[0040] Results and Discussion: The difference between Examples 1 and Examples 11-13 is that the types of rhodium salts are different, while other conditions are the same. It can be seen that by changing the type of rhodium salt, Rh-doped titanium dioxide photocatalysts can be prepared by water vapor-assisted solid-state method.

[0041] Comparative Example 1 As a control, the catalyst was prepared according to the following steps: Step 1: Weigh 0.0033 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 500 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0042] Comparative Example 2 Step 1: Weigh 0.00165 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 500 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0043] Comparative Example 3 Step 1: Weigh 0.00495 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 500 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0044] Comparative Example 4 Step 1: Weigh 0.0989 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 500 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0045] Comparative Example 5 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 800 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0046] Comparative Example 6 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 900 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0047] Comparative Example 7 Step 1: Weigh 0.00330 g RhCl3·3H2O and 1.0000 g TiO2, add a certain amount of deionized water and disperse by ultrasonication, then stir and evaporate to dryness in an 80 ℃ water bath to obtain precursor powder; Step 2: The precursor powder obtained above is calcined in a muffle furnace at 1000 °C for 1 h using a conventional solid-state method to obtain the final powder.

[0048] Test Example 1 like Figure 2 As shown, the X-ray powder diffraction (XRD) results of the samples prepared in Example 1 and Comparative Example 1 indicate that the presence of water vapor is beneficial for diffusing Rh ions with larger ionic radii. 3+ Ions are incorporated into the titanium dioxide lattice. For example... Figure 3 As shown, the X-ray photoelectron spectroscopy (XPS) of the samples prepared in Example 1 and Comparative Example 1 further demonstrates that Rh in the photocatalyst prepared by the water vapor-assisted solid-state method... 3+ The content is much higher than that of catalysts prepared by traditional solid-state methods.

[0049] Test Example 2 The samples obtained in the examples and comparative examples were used as catalysts for the photocatalytic system to investigate its photocatalytic hydrogen production performance.

[0050] 1. Photocatalytic reaction solution: 100 mg of the prepared catalyst was dispersed in 80 mL of a solution containing 0.5 M ascorbic acid, and then 135 μL of H2PtCl6 solution was added. The mixture was then sonicated for 15 min.

[0051] 2. Photocatalytic Hydrogen Production Test: The photocatalytic hydrogen production reaction was carried out in a top-irradiation container connected to a glass-sealed gas circulation system. A 300 W xenon lamp (λ ≥ 420 nm) (PLS-SXE 300C, Perfect Light) equipped with a 420 nm cutoff filter was used as the visible light source. The hydrogen produced during the reaction was measured using an online gas chromatograph (Shimadzu; GC-2014C, MS-5A column, Ar as carrier gas) equipped with a thermal conductivity detector.

[0052] like Figure 4 As shown, the hydrogen production rates of the Rh-doped TiO2 photocatalysts prepared by the steam-assisted solid-state method in Example 1 and the conventional solid-state method in Comparative Example 1 were 129.2 μmol h⁻¹, respectively. -1 and 16.6 μmol h -1 .

[0053] Tables 1 and 2 show the photocatalytic hydrogen production activities of Rh-doped TiO2 synthesized by the conventional solid-state method and the water vapor-assisted solid-state method at different Rh doping concentrations and temperatures, respectively.

[0054] Table 1. Visible light photocatalytic hydrogen production activity of the examples and comparative examples at different Rh doping concentrations.

[0055] Table 2. Visible light photocatalytic hydrogen production activity of the examples and comparative examples at different calcination temperatures.

[0056] In summary, this invention prepares a rhodium-doped TiO2 photocatalyst via a simple water vapor-assisted solid-state method. This solves the problem of Rh+ doping at high temperatures. 3+ Easily oxidized to Rh 4+ The problem of Rh-doped TiO2 catalysts was addressed by doping with trivalent rhodium ions, resulting in photocatalytic hydrogen production activity superior to that obtained by traditional solid-state methods, while also exhibiting good stability. This provides a new approach for further research on Rh-doped TiO2 catalysts.

[0057] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a rhodium-rich trivalent doped titanium dioxide photocatalyst, characterized in that, The method includes the following steps: (1) Immerse rutile titanium dioxide powder in rhodium salt solution, disperse ultrasonically, stir in a water bath at 50~90 ℃ until uniform, and continue stirring until the solvent evaporates to obtain precursor powder; (2) The precursor powder obtained in step (1) is placed in a quartz tube and calcined in an air atmosphere rich in water vapor to obtain the trivalent rhodium-doped titanium dioxide photocatalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), the rhodium salt includes any one of rhodium chloride, rhodium nitrate, rhodium acetate, and ammonium rhodium chloride.

3. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of rhodium to titanium is 0.0005~0.03:

1.

4. The preparation method according to claim 1, characterized in that, In step (2), the roasting temperature is 500~1000℃ and the roasting time is 1~40 h.

5. The preparation method according to claim 4, characterized in that, In step (2), the heating rate during roasting is 2~6℃ min. -1 .

6. The preparation method according to claim 1, characterized in that, In step (2), during the calcination process, air is introduced into a water-containing bubbler, and air containing water vapor is introduced into the quartz tube so that the precursor powder is calcined in an environment rich in water vapor.

7. The application of a rhodium-rich trivalent doped titanium dioxide photocatalyst prepared by any one of claims 1-6 in photocatalytic reactions.

8. The application according to claim 7, characterized in that: The photocatalytic reaction is a photocatalytic water splitting reaction to produce hydrogen, specifically: the trivalent rhodium-doped titanium dioxide photocatalyst is dispersed in an aqueous solution containing a hole sacrificial agent and a co-catalyst, and the hydrogen production reaction is carried out under light irradiation.

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