Red titanium dioxide out-phase junction as well as preparation method and application thereof

Abstract

The invention provides a red titanium dioxide out-phase junction as well as a preparation method and application thereof, and belongs to the technical field of material synthesis and renewable clean energy utilization. The preparation method of the red titanium dioxide out-phase junction comprises the following steps: forming a first precursor of B-doped titanium dioxide; calcining the first precursor at a high temperature to obtain a B-doped titanium dioxide out-phase junction second precursor; and mixing any one of (NH4) 2TiF6, NH4TiOF3 and (NH4) 2TiOF4 with the second precursor, and carrying out nitrogen treatment in an ammonia gas flow to obtain the rutile phase and anatase phase uniformly doped red titanium dioxide out-phase junction. According to the invention, titanium dioxide in a rutile phase can be nitrided through ammonium fluotitanate treatment, so that a red titanium dioxide out-phase junction uniformly doped with two phases of rutile and anatase is formed, and the red titanium dioxide out-phase junction shows relatively high water oxidation activity in a photocatalytic water decomposition reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of material synthesis and renewable clean energy utilization, and specifically relates to a red titanium dioxide heterogeneous junction and a preparation method and application thereof. Background Art

[0002] Titanium dioxide is the main material in the field of photocatalysis, but its absorption spectrum is mainly in the ultraviolet region, which limits its application. The means to expand the absorption spectrum of semiconductor photocatalytic materials include doping with cations, doping with anions, forming solid solutions, and surface disordering. There have been a lot of research works on the modification of titanium dioxide. For example, in 2001, R. Asahi found that TiO 2-x N x It can significantly improve the visible light absorption of titanium dioxide, opening the prelude to the visible light response modification of catalysts. However, there are two outstanding problems with nitrogen-doped titanium dioxide systems: (1) Nitrogen atom doping is generally concentrated on the surface, and it is impossible to achieve uniform doping in the bulk phase; (2) There is a difference in the valence state of nitrogen atoms and oxygen atoms, and doping will cause charge imbalance in the material and increase the photogenerated charge recombination center. Secondly, in 2022, Professor Chen Xiaobo reported that the titanium dioxide surface was disordered by surface hydrogen reduction treatment, and its absorption spectrum could reach 1000nm. However, this method is not conducive to chemical reactions that require clear surface adsorption points to start the photocatalytic process, that is, it is not conducive to the smooth progress of such reactions.

[0003] However, heterogeneous junctions can effectively promote charge separation. Titanium dioxide has two phases, rutile and anatase. The activity of pure rutile or anatase phase titanium dioxide in photocatalytic reforming is low, but the activity of titanium dioxide in which the two phases coexist is significantly improved in photocatalytic methanol reforming, which proves that "heterogeneous junctions" can effectively promote charge separation. However, the physical phase of red titanium dioxide is mainly anatase phase, and rutile phase red titanium dioxide cannot be synthesized.

[0004] To address this problem, currently, simple calcination is used to synthesize boron-doped rutile and anatase phases. However, a large amount of boron element will be lost through calcination alone. Generally, the doping process mainly occurs on the outer surface of the material, and uniform doping of the two phases cannot be achieved, resulting in shoulder-shaped absorption in the absorption spectrum, which limits its absorption of visible light and thus affects the utilization of solar energy. Summary of the invention

[0005] The present disclosure aims to solve at least one of the technical problems existing in the prior art and provide a red titanium dioxide heterogeneous junction and a preparation method and application thereof.

[0006] In one aspect of the present disclosure, a method for preparing a red titanium dioxide heterogeneous junction is provided, the preparation method comprising:

[0007] forming a first precursor of B-doped titanium dioxide;

[0008] calcining the first precursor at a high temperature to obtain a second precursor of a B-doped titanium dioxide heterogeneous junction;

[0009] Any one of (NH4)2TiF6, NH4TiOF3, (NH4)2TiOF4 is mixed with the second precursor and then subjected to nitridation treatment in an ammonia flow to obtain a red titanium dioxide heterogeneous junction uniformly doped with rutile phase and anatase phase.

[0010] Optionally, the first precursor for forming B-doped titanium dioxide comprises:

[0011] TiB2 is hydrothermally treated in a H2SO4 solution system to obtain a first precursor.

[0012] Optionally, the H2SO4 solution system is a mixed solution system of HCl and Na2SO4.

[0013] Optionally, the concentration of the HCl is 0.5-1.5M, and the concentration of the Na2SO4 is 0.05-0.2M.

[0014] Optionally, the temperature of the hydrothermal treatment is 180-200° C., and the time is 6-24 hours.

[0015] Optionally, the high temperature calcination is carried out at a temperature of 600 to 750° C. and for a time of 1 to 2 hours.

[0016] Optionally, the molar ratio of the ammonium fluorotitanate to the second precursor is (0-0.5):1.

[0017] Optionally, the temperature of the nitriding treatment is 500-600° C., and the time is 1-2 hours.

[0018] During the nitriding treatment, the ammonia gas flow rate is 50 to 100 mL / min.

[0019] In another aspect of the present disclosure, a red titanium dioxide heterogeneous junction is provided, which is prepared according to the preparation method described above.

[0020] Another aspect of the present disclosure provides an application of a red titanium dioxide heterogeneous junction, wherein the red titanium dioxide heterogeneous junction described above is applied to decompose water.

[0021] The present disclosure proposes a red titanium dioxide heterogeneous junction and a preparation method and application thereof. The preparation method of the red titanium dioxide heterogeneous junction includes: forming a first precursor of B-doped titanium dioxide; calcining the first precursor at high temperature to obtain a second precursor of the B-doped titanium dioxide heterogeneous junction; mixing any one of (NH4)2TiF6, NH4TiOF3, (NH4)2TiOF4 with the second precursor and then nitriding the mixture in an ammonia gas flow to obtain a red titanium dioxide heterogeneous junction. The present disclosure can nitridize titanium dioxide in the rutile phase by treating it with ammonium fluorotitanate to form a red titanium dioxide heterogeneous junction uniformly doped with rutile and anatase phases, which exhibits water oxidation activity in the photocatalytic water decomposition reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flowchart of a method for preparing a red titanium dioxide heterogeneous junction according to an embodiment of the present disclosure;

[0023] Figure 2 XRD diagrams of titanium dioxide heterogeneous junctions in Example 1 and Comparative Example 1 of the present disclosure;

[0024] Figure 3 It is a UV-vis diagram of the titanium dioxide heterogeneous junction in Example 1 of the present disclosure and Comparative Example 1;

[0025] Figure 4 This is an activity diagram of hydrogen production by decomposing water using titanium dioxide heterogeneous junctions in Example 1 of the present disclosure and Comparative Example 1. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0027] like Figure 1 As shown, in one aspect of the present disclosure, a method S100 for preparing a red titanium dioxide heterogeneous junction is provided, which specifically comprises the following steps S110 to S130:

[0028] S110, forming a first precursor of B-doped titanium dioxide.

[0029] Specifically, the first precursor is prepared by a hydrothermal method, that is, TiB2 is used as a raw material and hydrothermally treated in a H2SO4 solution system to obtain the first precursor.

[0030] It should be noted that, in the hydrothermal treatment, as long as the H2SO4 solution system is ensured, sulfate helps to control the crystal form. For example, the H2SO4 solution system adopts a solution system mixed with HCl and Na2SO4, wherein the concentration of HCl is preferably 0.5-1.5M, for example, 0.5M, 0.7M, 1.0M, 1.2M, 1.5M, etc., and the concentration of Na2SO4 is preferably 0.05-0.2MM, for example, 0.05M, 0.1M, 0.12M, 0.15M, etc. Of course, H2SO4 solution systems formed by other components can also be used, and there is no specific limitation on this.

[0031] As a further preferred embodiment, the ratio of the concentration of HCl to the concentration of Na2SO4 is preferably 10:1. For example, the concentration of HCl is preferably 1M, and the concentration of Na2SO4 is preferably 0.1M. Of course, in other preferred embodiments, other concentration ratios can also be selected, and there is no specific limitation on this.

[0032] In other preferred embodiments, the temperature of the hydrothermal treatment is 180-200°C, for example, 180°C, 190°C, 200°C, etc., and the time of the hydrothermal treatment is 6-24h, for example, 6h, 8h, 10h, 15h, 20h, 24h, etc.

[0033] S120, calcining the first precursor at high temperature to obtain a second precursor of a B-doped titanium dioxide heterojunction.

[0034] Specifically, the first precursor is cooled and centrifuged, and then placed in a muffle furnace for calcination to obtain a B-doped titanium dioxide heterogeneous junction, which is recorded as the second precursor.

[0035] In some preferred embodiments, the calcination temperature is 600-750°C, for example, 600°C, 650°C, 700°C, 750°C, etc., and the calcination time is 1-2h, for example, 1h, 1.5h, 2h, etc.

[0036] S130, mixing any one of (NH4)2TiF6, NH4TiOF3, (NH4)2TiOF4 with the second precursor and subjecting the mixture to nitridation treatment in an ammonia gas flow to obtain a red titanium dioxide heterogeneous junction uniformly doped with rutile phase and anatase phase.

[0037] In some preferred embodiments, the molar ratio of any one of (NH4)2TiF6, NH4TiOF3, (NH4)2TiOF4 to the second precursor is (0-0.5):1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, etc.

[0038] In other preferred embodiments, the temperature of the nitriding treatment is 500-600° C., for example, 500° C., 550° C., 600° C., etc., and the time is 1-2 h, for example, 1 h, 1.5 h, 2 h, etc.

[0039] In other preferred embodiments, during the nitridation treatment, the ammonia gas flow rate is 50-100 mL / min, for example, 50 mL / min, 70 mL / min, 100 mL / min, etc.

[0040] In this embodiment, a second precursor having a heterogeneous junction can be prepared by calcining a first precursor, and the second precursor is mixed with one of (NH4)2TiF6, NH4TiOF3, and (NH4)2TiOF4 and then nitrided to nitride the rutile phase of titanium dioxide, so that the rutile and anatase phases are uniformly doped in the interior and surface of the titanium dioxide to obtain a red titanium dioxide heterogeneous junction. The preparation method is simple and the absorption spectrum of the product is relatively wide.

[0041] In another aspect of the present disclosure, a red titanium dioxide heterogeneous junction is provided, which is prepared by the preparation method given above. For the specific preparation process, please refer to the above record, which will not be repeated here.

[0042] It should be understood that the red titanium dioxide heterogeneous phase provided in this embodiment refers to a mixed crystal form of rutile phase and anatase phase, that is, it includes two phases of rutile and anatase, that is, the two phases are uniformly doped in the interior and surface of the material, and compared with doping only on the external surface, this mixed crystal form of titanium dioxide has higher photocatalytic activity.

[0043] Another aspect of the present disclosure provides an application of a red titanium dioxide heterogeneous junction, in which the red titanium dioxide heterogeneous junction described above is applied to water decomposition, exhibiting high water oxidation activity in the photocatalytic water decomposition reaction, and effectively increasing hydrogen production.

[0044] The preparation method and application of red titanium dioxide heterogeneous junction will be further described below in conjunction with specific examples:

[0045] Example 1

[0046] This example proposes a method for preparing a red titanium dioxide heterogeneous junction, which mainly includes the following steps:

[0047] Step 1: Preparation of the first precursor (B-doped titanium dioxide)

[0048] Take 0.1g TiB2 and put it into a mixed solution of 60mL 1M HCl and 0.1M Na2SO4, stir for half an hour, and put it into a hydrothermal reactor for hydrothermal reaction. The reaction temperature is 180℃ and the hydrothermal time is 6h.

[0049] Step 2: Preparation of the second precursor (B-doped titanium dioxide heterogeneous junction)

[0050] The first precursor (B-doped titanium dioxide) was cooled and centrifuged, and calcined at 700° C. in air for 1 h.

[0051] Step 3: Preparation of red titanium dioxide heterogeneous structure

[0052] The molar ratio of ammonium fluorotitanate (NH4)2TiF6 and the second precursor is 0.3:1, and the nitridation is carried out in an ammonia gas flow of 100 mL / min. The nitridation temperature is 550°C and the nitridation time is 1 h.

[0053] like Figure 2 As shown, according to the XRD results, the red titanium dioxide heterogeneous phase obtained in Example 1 includes two phases, rutile and anatase.

[0054] like Figure 3 As shown, according to the UV-vis results, the maximum absorption peak of Example 1 is at 400nm, and the absorption band edge can be extended to 600nm, showing the characteristics of band-to-band transition absorption.

[0055] Furthermore, the titanium dioxide heterogeneous junction prepared in Example 1 was used as a photocatalyst to conduct an activity evaluation experiment for photocatalytic water decomposition, and the reaction conditions were as follows:

[0056] 50mg titanium dioxide heterogeneous junction sample, 100mL H2O, 5mM Fe(NO3)3, 300W xenon lamp light source.

[0057] like Figure 4 As shown, according to the water decomposition hydrogen production activity diagram, the titanium dioxide heterogeneous junction photocatalyst of Example 1 photocatalytically decomposes water under light source and exhibits high oxygen production activity.

[0058] Comparative Example 1

[0059] This example proposes a method for preparing a red titanium dioxide heterogeneous junction, which mainly includes the following steps:

[0060] Step 1: Preparation of the first precursor (B-doped titanium dioxide)

[0061] Take 0.1g TiB2 and put it into a mixed solution of 60mL 1M HCl and 0.1M Na2SO4, stir for half an hour, and put it into a hydrothermal reactor for hydrothermal reaction. The reaction temperature is 180℃ and the hydrothermal time is 6h.

[0062] Step 2: Preparation of the second precursor (B-doped titanium dioxide heterogeneous junction)

[0063] The first precursor (B-doped titanium dioxide) was cooled and centrifuged, and calcined at 700° C. in air for 1 h.

[0064] Step 3: Preparation of red titanium dioxide heterogeneous structure

[0065] The nitridation was carried out in an ammonia gas flow of 100 mL / min, the nitridation temperature was 550° C., and the nitridation time was 1 h.

[0066] like Figure 2 As shown, according to the XRD results, the red titanium dioxide heterogeneous phase obtained in this comparative example 1 includes two phases, rutile and anatase.

[0067] like Figure 3 As shown, according to the UV-vis results, the maximum absorption peak of Comparative Example 1 is at 350nm, and the absorption band edge is at 550nm, showing the characteristics of shoulder-shaped absorption.

[0068] Furthermore, the titanium dioxide heterogeneous junction prepared in this comparative example 1 was used as a photocatalyst to carry out an activity evaluation experiment for photocatalytic water decomposition, and the reaction conditions were as follows:

[0069] 50mg titanium dioxide heterogeneous junction sample, 100mL H2O, 5mM Fe(NO3)3, 300W xenon lamp light source.

[0070] like Figure 4 As shown, according to the water decomposition hydrogen production activity diagram, the titanium dioxide heterogeneous junction photocatalyst of Comparative Example 1 has a low oxygen production activity when photocatalytically decomposing water under light source.

[0071] In summary, Example 1 achieves the preparation of a red titanium dioxide heterojunction, with uniform nitrogen doping, a saturated absorption spectrum, and a high oxygen production activity. However, the color of Comparative Example 1 is dark red and brown, indicating that the nitrogen doping is uneven and the absorption spectrum is not saturated without the addition of ammonium fluorotitanate, which affects the light absorption efficiency in the photocatalyst reaction, and the oxygen production activity is significantly lower than that of Example 1.

[0072] The present disclosure proposes a red titanium dioxide heterogeneous junction and a preparation method and application thereof, which have the following beneficial effects compared with the prior art: the present disclosure forms B-doped titanium dioxide by a hydrothermal method, uses it as a precursor, and further prepares a precursor II having a heterogeneous junction by calcination, and further mixes it with ammonium fluorotitanate and then nitrides it to prepare a red titanium dioxide heterogeneous junction. This method can form a titanium dioxide heterogeneous junction uniformly doped with rutile phase and anatase phase, and the product exhibits high water decomposition activity in a photocatalytic water decomposition reaction.

[0073] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A method for preparing a red titanium dioxide heterogeneous junction, characterized in that: The preparation method comprises: forming a first precursor of B-doped titanium dioxide; calcining the first precursor at a high temperature to obtain a second precursor of a B-doped titanium dioxide heterogeneous junction; Any one of (NH4)2TiF6, NH4TiOF3, (NH4)2TiOF4 is mixed with the second precursor and then subjected to nitridation treatment in an ammonia flow to obtain a red titanium dioxide heterogeneous junction uniformly doped with rutile phase and anatase phase.

2. The preparation method according to claim 1, characterized in that: The first precursor for forming B-doped titanium dioxide comprises: TiB2 is hydrothermally treated in a H2SO4 solution system to obtain a first precursor.

3. The preparation method according to claim 2, characterized in that: The H2SO4 solution system is a mixed solution system of HCl and Na2SO4.

4. The preparation method according to claim 3, characterized in that: The concentration of the HCl is 0.5-1.5M, and the concentration of the Na2SO4 is 0.05-0.2M.

5. The preparation method according to claim 2, characterized in that: The temperature of the hydrothermal treatment is 180-200°C and the time is 6-24h.

6. The preparation method according to claim 1, characterized in that: The high temperature calcination is carried out at a temperature of 600 to 750° C. and for a time of 1 to 2 hours.

7. The preparation method according to claim 1, characterized in that: The molar ratio of the ammonium fluorotitanate to the second precursor is (0-0.5):

1.

8. The preparation method according to claim 1, characterized in that: The temperature of the nitriding treatment is 500-600° C., the time is 1-2 hours, and the ammonia gas flow rate is 50-100 mL / min.

9. A red titanium dioxide heterogeneous junction, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 8.

10. An application of a red titanium dioxide heterogeneous junction, characterized in that: The red titanium dioxide heterogeneous junction described in claim 9 is used for decomposing water.

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