A method for preparing a Schottky-type photocatalyst

Abstract

The invention provides a method for preparing a Schottky-type photocatalyst, which relates to the technical field of photocatalysis, and comprises the following steps: S1: acidifying, stripping and reorganizing layered KTiNbO5 in sequence to obtain H+-recombined HTiNbO5 nanosheets (HTiNbO5-Ns); S2: washing and drying the H+-recombined HTiNbO5 nanosheets (HTiNbO5-Ns); the invention uses KTiNbO5 as a raw material and undergoes three processes of acidification, stripping and reorganization to obtain H+-recombined HTiNbO5 nanosheets (HTiNbO5-Ns). + ‑Recombinant HTiNbO5 nanosheets (HTiNbO5‑Ns) have a larger surface area and porous structure. Ti3C2MXene is obtained by completely etching the Al layer in Ti3AlC2. A nanosheet Schottky heterojunction is constructed by combining it with a few-layer HTiNbO5 nanosheets using a simple hydrothermal method. The raw materials for the preparation are common and easily available, the process flow is simple, and the operation is convenient.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalysis, and in particular to a method for preparing a Schottky-type photocatalyst. Background Art

[0002] In today's world, the excessive consumption of non-renewable fossil fuels and the growing demand for energy are becoming one of the major problems facing mankind. Photocatalysis is considered to be a promising technology to use solar energy to solve the current environmental restoration and energy crisis. In order to meet the needs of industrial development, it is imperative to develop efficient visible light-driven photocatalysts.

[0003] Metal sulfide materials have been widely studied and applied in various photocatalytic fields due to their advantages such as visible light response, simple synthesis process, unique photoelectric properties and low price. Among them, the ternary semiconductor metal sulfide CdIn 2 S 4 (CIS) has attracted more and more attention due to its good band structure, good stability and easy availability. However, like most single photocatalysts, the poor separation effect of photogenerated carriers in CIS seriously restricts its photocatalytic ability under visible light. 3 C 2 As an emerging two-dimensional (2D) layered material, MXene has attracted extensive attention due to its large specific surface area, hydrophilicity and metallic conductivity. It is widely used in various photocatalytic fields. 3 C 2 The surface of MXene contains abundant functional groups such as -O, -OH, and -F, and can be used as a carrier substrate. It can not only provide excellent conditions for growing photocatalysts on the surface, but also effectively separate photogenerated electron-hole pairs. However, in the prior art, the photocatalyst preparation process is complicated, the equipment investment cost is high, and the photocatalytic performance and reduction performance are poor. Therefore, the present invention proposes a method for preparing a Schottky-type photocatalyst to solve the problems existing in the prior art. Summary of the invention

[0004] In view of the above problems, the present invention proposes a method for preparing a Schottky type photocatalyst. The preparation method of the Schottky type photocatalyst has common and easily available raw materials, a simple process flow, convenient operation, no need for too high a synthesis temperature, small equipment investment, and low reaction cost.

[0005] To achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a method for preparing a Schottky-type photocatalyst, comprising the following steps:

[0006] S1: Layered KTiNbO 5 Acidification, stripping and recombination are performed in sequence to obtain H+-recombined HTiNbO 5Nanosheets (HTiNbO 5 -Ns);

[0007] S2: H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns) was washed and dried to obtain a three-dimensional porous HTiNbO 5 -Ns;

[0008] S3: Ti 3 AlC 2 The powder was added to a HCl solution containing LiF, the Al layer was removed by acid etching, and the precipitate was obtained by centrifugal washing and vacuum drying to obtain layered Ti 3 C 2 MXene;

[0009] S4: Will HTiNbO 5 -Ns samples were dispersed in deionized water and Ti 3 C 2 MXene was transferred to an autoclave, heated and then cooled to room temperature, the precipitate was ground with ethanol, and heated overnight to obtain a photocatalyst.

[0010] A further improvement is that in S1, the acidification process comprises the following steps:

[0011] S111: KTiNbO 5 Mix with nitric acid solution and perform ultrasonic vibration;

[0012] S112: Heat to 60°C and stir for 12h;

[0013] S113: Filtration and washing to obtain a precipitate of layered HTiNbO 5 ,spare.

[0014] A further improvement is that in S1, the stripping process includes the following steps:

[0015] S121: The layered HTiNbO obtained during the acidification process 5 Mixing with deionized water, and then mechanically stirring to make the mixture uniform, to obtain a suspension;

[0016] S122: adding alkaline tetrabutylammonium hydroxide solution to the suspension until the pH value reaches 10;

[0017] S123: The solution after adjusting the pH value is reacted for 7 days to obtain HTiNbO 5 Nanosheet colloidal solution;

[0018] S124: HTiNbO 5The nanosheet colloidal solution is centrifuged, and the supernatant is selected for later use.

[0019] A further improvement is that in S1, the reorganization process includes the following steps:

[0020] S131: adding a dilute nitric acid solution to the upper colloidal solution obtained in the stripping process, causing sedimentation;

[0021] S132: The precipitate is H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns), spare.

[0022] A further improvement is that: S3 includes:

[0023] S31: Take the prepared Ti 3 AlC 2 powder, which is added to a HCl solution containing LiF;

[0024] S32: removing the Al layer by acid etching at 35°C;

[0025] S33: After stirring for 24 h, the product was centrifuged and washed several times with distilled water until the pH value of the liquid supernatant was about 7;

[0026] S34: The obtained precipitate was dried in vacuum at 60°C to obtain a layered Ti 3 C 2 MXene.

[0027] A further improvement is that in S31, the concentration of the HCl solution is controlled to be 9M.

[0028] A further improvement is that: said S4 comprises:

[0029] S41: HTiNbO 5 -Ns samples were dispersed in deionized water and ultrasonically stirred to obtain a uniform suspension;

[0030] S41: Add Ti to the homogeneous suspension 3 C 2 MXene, after sonication, the resulting blended solution was transferred to a polytetrafluoroethylene-lined autoclave and heated at 120 °C for 4.5–5.5 h;

[0031] S41: After naturally cooling to room temperature, the precipitate was centrifuged and ground with ethanol, and then heated at 60° C. overnight to obtain the final product photocatalyst.

[0032] The beneficial effects of the present invention are:

[0033] 1. The present invention uses KTiNbO 5The raw material is processed by acidification, stripping and reorganization to obtain H + -Recombinant HTiNbO 5 Nanosheets (HTiNbO 5 -Ns), with a larger surface area and porous structure, by 3 AlC 2 The Al layer in the Ti 3 C 2 MXene, and then reacted with few-layer HTiNbO by a simple hydrothermal method. 5 Nanosheets combined to construct Ti 3 C 2 MXene / HTiNbO 5 Nanosheet (MHTNS) Schottky heterojunction, in summary, the preparation raw materials are common and easy to obtain, the process flow is simple, the operation is convenient, the synthesis temperature does not need to be too high, the equipment investment is small, and the reaction cost is low.

[0034] 2. The MHTNS Schottky heterojunction prepared by the present invention exhibits excellent full-spectrum photocatalytic degradation performance of tetracycline hydrochloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Different samples of HTiNbO 5 (a, b), HTiNbO 5 -Ns(c), 1-MHTNS(d), 3-MHTNS(e), 5-MHTNS(f) and Ti 3 C 2 (g, h) SEM images;

[0036] Figure 2 The sample supernatant (a) of the present invention, HTiNbO 5 -Ns(b),Ti 3 C 2 TEM images of MXene (c) and 3-MHTNS (d); HRTEM images (e, f) and STEM-HAADF images (g) of sample 3-MHTNS; distribution of C / Ti / Nb / O elements on 3-MHTNS (hk);

[0037] Figure 3 is the XRD pattern of the present invention;

[0038] Figure 4 is the Raman spectrum of the present invention;

[0039] Figure 5 It is the ultraviolet visible diffuse reflectance spectrum of the present invention;

[0040] Figure 6 is a bandgap diagram of the present invention;

[0041] Figure 7 The HTiNbO 5 N-Ns and 3-MHTNS 2 Adsorption-desorption isotherm plot;

[0042] Figure 8 The HTiNbO 5 -Pore size distribution curves of Ns and 3-MHTNS;

[0043] Fig. 9 The photocatalytic degradation curve of tetracycline hydrochloride of different samples of the present invention;

[0044] Fig.10 The UV-vis spectrum change diagram of 3-MHTNS of the present invention. DETAILED DESCRIPTION

[0045] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0046] Embodiment 1

[0047] according to Figure 1-10 As shown, this embodiment proposes a method for preparing a Schottky-type photocatalyst, comprising the following steps:

[0048] Layered KTiNbO 5 Acidification, stripping and recombination are performed in sequence to obtain H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns).

[0049] The acidification process comprises the following steps: 5 The mixture was mixed with nitric acid solution, subjected to ultrasonic oscillation, and then heated to 60°C, stirred for 12 hours, and then filtered and washed to obtain a layered HTiNbO precipitate. 5 ,spare;

[0050] The stripping process comprises the following steps: 5 The mixture is mixed with deionized water and then mechanically stirred to mix evenly to obtain a suspension; then, an alkaline tetrabutylammonium hydroxide solution is added to the suspension until the pH value reaches 10; the solution after adjusting the pH value is reacted for 7 days to obtain HTiNbO 5 Nanosheet colloidal solution, HTiNbO 5 The nanosheet colloidal solution is centrifuged, and the supernatant is selected for use;

[0051] The reorganization process comprises the following steps: adding a dilute nitric acid solution to the upper colloidal solution obtained in the stripping process, causing sedimentation to occur, and obtaining a precipitate of H+-reorganized HTiNbO 5 Nanosheets (HTiNbO 5 -Ns), spare;

[0052] The obtained H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns) was washed and dried to obtain a three-dimensional porous HTiNbO 5 -Ns;

[0053] Take 2.0g of prepared Ti 3 AlC 2 The powder was added to 40 ml of HCl solution containing 3.2 g of LiF, where the concentration of the HCl solution was 9 M. The Al layer was removed by acid etching at 35 °C. After stirring for 24 h, the product was centrifuged and washed several times with distilled water until the pH value of the liquid supernatant was about 7. The resulting precipitate was dried in vacuum at 60 °C to obtain layered Ti 3 C 2 MXene.

[0054] Preparation of photocatalyst 1-MHTNS: 0.2 g HTiNbO 5 -Ns sample was dispersed in 60 mL of deionized water and ultrasonically stirred for 30 min to obtain a uniform suspension. Then 0.002 g Ti 3 C 2 MXene. After 5 min of ultrasonication, the resulting blend solution was transferred to a polytetrafluoroethylene-lined autoclave (100 mL) and heated at 120 °C for 5 h. After cooling naturally to room temperature, the precipitate was centrifuged and ground with ethanol for 20 min, and then heated at 60 °C overnight to obtain the final product.

[0055] Embodiment 2

[0056] according to Figure 1-10 As shown, this embodiment proposes a method for preparing a Schottky-type photocatalyst, comprising the following steps:

[0057] Layered KTiNbO 5 Acidification, stripping and recombination are performed in sequence to obtain H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns).

[0058] The acidification process comprises the following steps: 5The mixture was mixed with nitric acid solution, subjected to ultrasonic oscillation, and then heated to 60°C, stirred for 12 hours, and then filtered and washed to obtain a layered HTiNbO precipitate. 5 ,spare;

[0059] The stripping process comprises the following steps: 5 The mixture is mixed with deionized water and then mechanically stirred to mix evenly to obtain a suspension; then, an alkaline tetrabutylammonium hydroxide solution is added to the suspension until the pH value reaches 10; the solution after adjusting the pH value is reacted for 7 days to obtain HTiNbO 5 Nanosheet colloidal solution, HTiNbO 5 The nanosheet colloidal solution is centrifuged, and the supernatant is selected for use;

[0060] The reorganization process comprises the following steps: adding a dilute nitric acid solution to the upper colloidal solution obtained in the stripping process, causing sedimentation to occur, and obtaining a precipitate of H+-reorganized HTiNbO 5 Nanosheets (HTiNbO 5 -Ns), spare;

[0061] The obtained H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns) was washed and dried to obtain a three-dimensional porous HTiNbO 5 -Ns;

[0062] Take 2.0g of prepared Ti 3 AlC 2 The powder was added to 40 ml of HCl solution containing 3.2 g of LiF, where the concentration of the HCl solution was 9 M. The Al layer was removed by acid etching at 35 °C. After stirring for 24 h, the product was centrifuged and washed several times with distilled water until the pH value of the liquid supernatant was about 7. The resulting precipitate was dried in vacuum at 60 °C to obtain layered Ti 3 C 2 MXene.

[0063] Preparation of photocatalyst 3-MHTNS: 0.2 g HTiNbO 5 -Ns sample was dispersed in 60 mL of deionized water and ultrasonically stirred for 30 min to obtain a uniform suspension. Then 0.006 g Ti 3 C 2MXene. After 5 min of ultrasonication, the resulting blend solution was transferred to a polytetrafluoroethylene-lined autoclave (100 mL) and heated at 120 °C for 5 h. After cooling naturally to room temperature, the precipitate was centrifuged and ground with ethanol for 20 min, and then heated at 60 °C overnight to obtain the final product.

[0064] Embodiment 3

[0065] according to Figure 1-10 As shown, this embodiment proposes a method for preparing a Schottky-type photocatalyst, comprising the following steps:

[0066] Layered KTiNbO 5 Acidification, stripping and recombination are performed in sequence to obtain H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns).

[0067] The acidification process comprises the following steps: 5 The mixture was mixed with nitric acid solution, subjected to ultrasonic oscillation, and then heated to 60°C, stirred for 12 hours, and then filtered and washed to obtain a layered HTiNbO precipitate. 5 ,spare;

[0068] The stripping process comprises the following steps: 5 The mixture is mixed with deionized water and then mechanically stirred to mix evenly to obtain a suspension; then, an alkaline tetrabutylammonium hydroxide solution is added to the suspension until the pH value reaches 10; the solution after adjusting the pH value is reacted for 7 days to obtain HTiNbO 5 Nanosheet colloidal solution, HTiNbO 5 The nanosheet colloidal solution is centrifuged, and the supernatant is selected for use;

[0069] The reorganization process comprises the following steps: adding a dilute nitric acid solution to the upper colloidal solution obtained in the stripping process, causing sedimentation to occur, and obtaining a precipitate of H+-reorganized HTiNbO 5 Nanosheets (HTiNbO 5 -Ns), spare;

[0070] The obtained H+-recombined HTiNbO 5 Nanosheets (HTiNbO 5 -Ns) was washed and dried to obtain a three-dimensional porous HTiNbO 5 -Ns;

[0071] Take 2.0g of prepared Ti 3 AlC 2The powder was added to 40 ml of HCl solution containing 3.2 g of LiF, where the concentration of the HCl solution was 9 M. The Al layer was removed by acid etching at 35 °C. After stirring for 24 h, the product was centrifuged and washed several times with distilled water until the pH value of the liquid supernatant was about 7. The resulting precipitate was dried in vacuum at 60 °C to obtain layered Ti 3 C 2 MXene.

[0072] Preparation of photocatalyst 5-MHTNS: 0.2 g HTiNbO 5 -Ns sample was dispersed in 60mL deionized water and ultrasonically stirred for 30min to obtain a uniform suspension. Then 0.01gTi 3 C 2 MXene. After 5 min of ultrasonication, the resulting blend solution was transferred to a polytetrafluoroethylene-lined autoclave (100 mL) and heated at 120 °C for 5 h. After cooling naturally to room temperature, the precipitate was centrifuged and ground with ethanol for 20 min, and then heated at 60 °C overnight to obtain the final product.

[0073] Verification example:

[0074] Depend on Figure 1-10 As shown, the Schottky-type photocatalyst prepared in the present application has a larger surface area and a porous structure, and exhibits excellent full-spectrum photocatalytic degradation performance of tetracycline hydrochloride.

[0075] The present invention uses KTiNbO 5 The raw material is processed by acidification, stripping and reorganization to obtain H + -Recombinant HTiNbO 5 Nanosheets (HTiNbO 5 -Ns), with a larger surface area and porous structure, by 3 AlC 2 The Al layer in the Ti 3 C 2 MXene, and then reacted with few-layer HTiNbO by a simple hydrothermal method. 5 Nanosheets combined to construct Ti 3 C 2 MXene / HTiNbO 5 Nanosheet (MHTNS) Schottky heterojunction, in summary, the preparation raw materials are common and easy to obtain, the process flow is simple, the operation is convenient, the synthesis temperature does not need to be too high, the equipment investment is small, and the reaction cost is low; and the MHTNS Schottky heterojunction prepared by the present invention shows excellent full-spectrum photocatalytic degradation of tetracycline hydrochloride performance.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a Schottky-type photocatalyst, characterized in that: The following steps are involved: S1: The layered KTiNbO5 is acidified, stripped and reorganized in sequence to obtain H + - Recombinant HTiNbO5 nanosheets HTiNbO5-Ns; S2: For H + - Recombined HTiNbO5 nanosheets HTiNbO5-Ns are washed and dried to obtain HTiNbO5-Ns with a three-dimensional porous structure; S3: Ti3AlC2 powder was added to a HCl solution containing LiF, and the Al layer was removed by acid etching at 35 °C. After stirring for 24 h, the mixture was centrifuged and washed several times with distilled water until the pH value of the liquid supernatant was 7, and then vacuum dried at 60 °C to obtain layered Ti3C2 MXene. S4: The HTiNbO5-Ns sample was dispersed in deionized water, Ti3C2 MXene was added, and the mixture was transferred to an autoclave. The mixture was heated at 120 °C for 4.5-5.5 h, and then cooled to room temperature naturally. The precipitate was ground with ethanol and heated at 60 °C overnight to obtain a photocatalyst. The photocatalyst is applied to full-spectrum photocatalytic degradation of tetracycline hydrochloride.

2. The method for preparing a Schottky-type photocatalyst according to claim 1, characterized in that: In S1, the acidification process comprises the following steps: S111: mixing KTiNbO5 with nitric acid solution and performing ultrasonic vibration; S112: Heat to 60°C and stir for 12h; S113: Filter and wash to obtain a precipitate of layered HTiNbO5 for later use.

3. The method for preparing a Schottky-type photocatalyst according to claim 2, characterized in that: In S1, the stripping process includes the following steps: S121: mixing the layered HTiNbO5 obtained in the acidification process with deionized water, and then mechanically stirring the mixture to obtain a suspension; S122: adding alkaline tetrabutylammonium hydroxide solution to the suspension until the pH value reaches 10; S123: the solution after adjusting the pH value is reacted for 7 days to obtain a HTiNbO5 nanosheet colloidal solution; S124: Centrifuge the HTiNbO5 nanosheet colloidal solution and select the supernatant for later use.

4. The method for preparing a Schottky-type photocatalyst according to claim 3, characterized in that: In S1, the reorganization process includes the following steps: S131: adding a dilute nitric acid solution to the upper colloidal solution obtained in the stripping process, causing sedimentation; S132: The precipitate is H + -Recombined HTiNbO5 nanosheets HTiNbO5-Ns, for later use.

5. The method for preparing a Schottky-type photocatalyst according to claim 1, characterized in that: In S3, the concentration of HCl solution is controlled to be 9M.

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