Nitride ta 3n 5, and preparation method therefor and use thereof

Abstract

The present application discloses a nitride Ta3N5, and a preparation method therefor and a use thereof. The specific method comprises: subjecting a precursor I to high-temperature hydrolysis to prepare TaOx having a small size; and by utilizing the characteristics of TaOx being amorphous and having a small particle radius, performing short-duration nitridation on same to prepare Ta3N5. The formation of low-valence metal defects is effectively reduced, the charge separation efficiency is improved, and water-splitting activity is exhibited in a photocatalytic water splitting reaction. Compared with Ta3N5 prepared by a conventional method, the activity of the product of the present application is significantly improved.

Description

Nitride Ta3N5, preparation method and application thereof

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202411282639.3, filed on September 13, 2024, entitled "Nitride Ta3N5, preparation method and application thereof", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the technical field of material synthesis and renewable clean energy utilization, and specifically relates to a nitride Ta3N5, a preparation method and application thereof. BACKGROUND

[0004] (Oxy)nitrides have suitable band gaps and conduction / valence band positions, and can be used for water decomposition, and are considered as a class of highly attractive visible light responsive photocatalysts. However, these (oxy)nitride photocatalysts are generally synthesized by high-temperature solid-phase method, and the precursor particles have a large radius, which requires a longer time for complete nitridation, and inevitably produces more anion vacancies or low-valence metal species. Anion vacancies or low-valence metal species are usually considered as recombination centers, which reduces the photocatalyst activity.

[0005] The traditional synthesis method of nitride Ta3N5 is to directly nitride the oxide precursor Ta2O5. However, due to the large size of the precursor particles and the long high-temperature nitriding process, the low-valence defect density is increased, and the charge separation ability is reduced.

[0006] Currently, researchers have made many attempts to suppress the defects of oxy-nitride compounds, mainly including:

[0007] (1) Doping low-valence metals, that is, by doping low-valence metal species (such as Mg, Sc, Zr, etc.) which are not easy to be reduced to suppress the generation of low-valence metal defects;

[0008] (2) Molten salt-assisted nitridation, that is, by molten salt-assisted nitridation, the synthesis path is changed, and the material activity is improved, such as using Na2CO3 to assist the nitridation of Ta2O5 precursor, first generating Na2Ta2O6, and then volatilizing potassium ions to generate Ta3N5 by nitridation;

[0009] (3) Reducing the nitriding time, that is, by short-time high-temperature nitriding of KTaO3 precursor, high-quality, low-defect Ta3N5 nanorods are obtained at the edge of KTaO3, unfortunately, short-time nitridation cannot completely convert the precursor oxide into (oxy)nitride, and the Ta3N5 nanorods are mainly located on the surface of the material.

[0010] All three methods have their merits, but for suppressing defects in low-valence metals, the strategy of reducing nitriding time has the highest priority, because the number of low-valence metal defects can be controlled by changing the precursor or molten salt type.

[0011] Traditional methods for reducing nitriding time mainly involve shrinking the geometry of the precursor, specifically through the sol-gel method to prepare oxide precursors. Summary of the Invention

[0012] The purpose of this section is to outline some aspects of the embodiments of this application and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents, and such simplifications or omissions should not be construed as limiting the scope of this application.

[0013] In view of the problems mentioned above and / or existing in the prior art, this application is made.

[0014] Therefore, the purpose of this application is to overcome the shortcomings of the prior art and provide a method for preparing nitride Ta3N5.

[0015] To solve the above-mentioned technical problems, this application provides the following technical solution: including,

[0016] Precursor I was hydrolyzed at high temperature to give the amorphous product TaO x ;

[0017] TaO x High-temperature nitriding yields Ta3N5;

[0018] The precursor I includes ATaP2O8 and A3TaP2O9, where A is selected from either K or Na.

[0019] As an optional method for preparing the nitride Ta3N5 described in this application, the high-temperature hydrolysis temperature of the precursor I is 80-100°C, and the time is 1-2 hours.

[0020] As an optional method for preparing the nitride Ta3N5 described in this application, the high-temperature hydrolysis process of the precursor I includes adding 1-5M AOH solution, wherein A is selected from either K or Na.

[0021] As an optional method for preparing the nitride Ta3N5 described in this application, the ATaP2O8 is prepared by a high-temperature solid-state method using a mixture of A precursor, Ta precursor, P precursor and AP precursor as raw materials, wherein the molar ratio of A, Ta, P and AP is 1:1:2:(0~10).

[0022] The A3TaP2O9 is prepared by a high-temperature solid-state method using A precursor, Ta precursor, P precursor and AP mixed precursor as raw materials, wherein the molar ratio of A, Ta, P and AP is 3:1:2:(0~10).

[0023] As an optional method for preparing the nitride Ta3N5 described in this application, the A precursor includes at least one of the carbonate, oxalate, and nitrate of A.

[0024] The Ta precursor is Ta2O. 5；

[0025] The P precursor is NH4H2PO 4；

[0026] The AP hybrid precursor includes H3PO4 and AH2PO4. 4、 At least two of A2HPO4.

[0027] As an optional method for preparing the nitride Ta3N5 described in this application, the high-temperature solid-state method is performed at a temperature of 800–900°C for 5–15 hours.

[0028] As an optional method for preparing the nitride Ta3N5 described in this application, the high-temperature nitriding is carried out in an ammonia gas flow of 200-300 mL / min at a temperature of 850-1000 °C for 3-10 h.

[0029] Another object of this application is to provide a method for preparing Ta3N5 nitride.

[0030] Another objective of this application is to provide the application of nitride Ta3N5 in photocatalytic oxygen production.

[0031] The beneficial effects of this application are:

[0032] This application describes a method to prepare smaller-sized TaO by high-temperature hydrolysis of precursor I. x Using TaO x Due to its amorphous shape and small particle radius, Ta3N5 nitride can be prepared in a short time by nitriding, which effectively reduces the formation of low-valence metal defects and improves charge separation efficiency. It exhibits water-splitting activity in photocatalytic water splitting reaction, and its activity is significantly improved compared with Ta3N5 prepared by conventional methods. Attached Figure Description

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort. Among them:

[0034] Fig. 1 is a scanning electron microscope image of Ta3N5 prepared in Example 1 and Comparative Examples 1 and 2 of the present application.

[0035] Fig. 2 is an XRD image of Ta3N5 prepared in Example 1 and Comparative Examples 1 and 2 of the present application.

[0036] Fig. 3 is a decomposition water oxygen production activity image of Ta3N5 prepared in Example 1 and Comparative Examples 1 and 2 of the present application. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with the description of the embodiments.

[0038] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0039] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent of or selected from other embodiments.

[0040] The raw materials used in the present application are commercially available in the art without special instructions.

[0041] Example 1

[0042] The present embodiment provides a preparation method of Ta3N5, specifically:

[0043] 1) Synthesis of precursor I:

[0044] According to the molar ratio of Na, Ta, P, AP(1), AP(2) being 3:1:2:2:2, Na2CO3, Ta2O5, NH4H2PO4, NaH2PO4 and Na2HPO4 are mixed and ground to make them uniformly mixed, and then calcined at 900℃ for 8h to prepare the precursor I Na3TaP2O9.

[0045] 2) High temperature hydrolysis of precursor I:

[0046] The precursor I Na3TaP2O9 was heated in water bath, the heating temperature was 80℃, and the time was 1h. After hydrothermal treatment, the powder was obtained by cooling and centrifugation, which was the amorphous product TaO x , wherein the supernatant was directly cooled and centrifuged, and the lower precipitate was repeatedly heated in water bath as many times as possible to dissolve the precipitate, and then the amorphous product TaO was obtained by cooling and centrifugation. x .

[0047] 3) TaO x High temperature nitridation:

[0048] TaO x The nitridation was carried out in an ammonia gas flow of 250mL / min, the nitridation temperature was 900℃, and the nitridation time was 5h, so that the nitride Ta3N5 was obtained, which was recorded as Ta3N5-KP.

[0049] Comparative Example 1

[0050] This comparative example provides another method for synthesizing the nitride Ta3N5, specifically:

[0051] 1) Synthesis of precursor I:

[0052] According to the molar ratio of Na, Ta and P of 3:1:2, Na2CO3, Ta2O5, NH4H2PO4 were mixed and ground to make them uniformly mixed, and then calcined at 900℃ for 8h to prepare the precursor I Na3TaP2O9.

[0053] 2) High temperature nitridation of Na3TaP2O9:

[0054] The nitridation of Na3TaP2O9 was carried out in an ammonia gas flow of 250mL / min, the nitridation temperature was 950℃, and the nitridation time was 15h, so that the nitride Ta3N5 was obtained, which was recorded as Ta3N5-1.

[0055] Comparative Example 2

[0056] This comparative example provides another method for synthesizing the nitride Ta3N5, specifically:

[0057] 1) Synthesis of precursor I:

[0058] According to the molar ratio of Na, Ta, P, AP(1), and AP(2) of 3:1:2:2:2, Na2CO3, Ta2O5, NH4H2PO4, NaH2PO4 and Na2HPO4 were mixed and ground to make them uniformly mixed, and then calcined at 900℃ for 8h to prepare the precursor I Na3TaP2O9.

[0059] 2) High temperature nitridation of Na3TaP2O9:

[0060] Na3TaP2O9 was nitrided at 950℃ for 15h under 250mL / min ammonia gas flow to obtain nitride Ta3N5, denoted as Ta3N5-2.

[0061] Figure 1 is a scanning electron microscope image of the nitride Ta3N5 prepared in Example 1 and Comparative Examples 1 and 2, and Figure 2 is an XRD image of Example 1 and Comparative Examples 1 and 2, which can prove that the nitride Ta3N5 is successfully synthesized according to the scheme of the examples and comparative examples.

[0062] Application test

[0063] The nitride Ta3N5 synthesized in the examples or comparative examples was used for the photocatalytic oxygen evolution reaction. Specifically, the reaction conditions included:

[0064] 500mg of Ta3N5 sample loaded with 2wt% CoO x , 500mg La2O3, 1.6988g AgNO3, 200mL H2O, and 300W xenon lamp light source;

[0065] The results are shown in Figure 3, which shows that the nitride Ta3N5 prepared in the present application can realize the photocatalytic oxygen evolution half-reaction after loading the corresponding oxygen evolution cocatalyst. With the extension of the reaction time, the oxygen evolution rate decreases, because the sacrificial agent AgNO3 is reduced to Ag element and deposited on Ta3N5, resulting in light absorption being blocked and the reaction activity being reduced, which is a common phenomenon. This experiment proves that the generated Ta3N5 has photocatalyst oxygen evolution performance, and the photocatalyst oxygen evolution performance of the nitride prepared in Comparative Example 1 and Comparative Example 2 is significantly improved.

[0066] Example 2

[0067] 1) Synthesis of precursor I:

[0068] Na2CO3, Ta2O5, NH4H2PO4, NaH2PO4 and Na2HPO4 were mixed and ground in a molar ratio of Na:Ta:P:AP(1):AP(2) of 3:1:2:2:2, and were mixed uniformly, and were calcined at 850℃ for 12h to obtain the precursor I Na3TaP2O9.

[0069] 2) High temperature hydrolysis of precursor I:

[0070] The precursor I Na3TaP2O9 was heated in a water bath, the heating temperature was 100℃, and the heating time was 1h. After hydrothermal treatment, the powder obtained after cooling and centrifugation was the amorphous product TaO xThe supernatant is directly cooled and centrifuged, the lower precipitate is repeatedly heated in a water bath, and the solution precipitate is maximized, and then the amorphous product TaO is obtained by cooling and centrifugation x .

[0071] 3) TaO x High-temperature nitridation:

[0072] TaO x The nitride Ta3N5 is obtained by nitriding at an ammonia gas flow of 200 mL / min and a nitriding temperature of 1000°C for 3h.

[0073] Example 3

[0074] 1) Synthesis of precursor I:

[0075] Na2CO3, Ta2O5, NH4H2PO4, NaH2PO4 and Na2HPO4 are mixed and ground in a molar ratio of Na:Ta:P:AP(1):AP(2) of 3:1:2:2:2, and then uniformly mixed and calcined at 800°C for 15h to obtain the precursor I Na3TaP2O9.

[0076] 2) High-temperature hydrolysis of precursor I:

[0077] The precursor I Na3TaP2O9 is heated in a water bath at a temperature of 90°C for 2h, and then the powder obtained by cooling and centrifugation after hydrothermal treatment is the amorphous product TaO x The supernatant is directly cooled and centrifuged, the lower precipitate is repeatedly heated in a water bath, and the solution precipitate is maximized, and then the amorphous product TaO is obtained by cooling and centrifugation x .

[0078] 3) TaO x High-temperature nitridation:

[0079] TaO x The nitride Ta3N5 is obtained by nitriding at an ammonia gas flow of 300 mL / min and a nitriding temperature of 850°C for 9h.

[0080] Example 4

[0081] 1) Synthesis of precursor I:

[0082] Na2CO3, Ta2O5, NH4H2PO4, NaH2PO4 and Na2HPO4 are mixed and ground in a molar ratio of Na:Ta:P:AP(1):AP(2) of 3:1:2:2:2, and then uniformly mixed and calcined at 900°C for 5h to obtain the precursor I Na3TaP2O9.

[0083] 2) High-temperature hydrolysis of precursor I:

[0084] Precursor I, Na3TaP2O9, was heated in a water bath at 80°C for 2 hours. After hydrothermal treatment, it was cooled and centrifuged to obtain a powder, which is the amorphous product, TaO. x The supernatant was directly cooled and centrifuged, while the lower precipitate was repeatedly heated in a water bath to facilitate precipitation. After cooling and centrifugation, the amorphous product TaO was obtained. x .

[0085] 3) TaO x High-temperature nitriding:

[0086] TaO x Nitriding was carried out in an ammonia gas flow of 200 mL / min at a nitriding temperature of 850 °C for 10 h to obtain the nitride Ta3N5.

[0087] The nitride Ta3N5 obtained by referring to the methods of Examples 2 to 4 has similar properties to the product of Example 1.

[0088] In summary, this application demonstrates that small-sized TaO can be prepared by high-temperature hydrolysis of precursor I. x Using TaO x Due to its amorphous shape and small particle radius, Ta3N5 nitride can be prepared in a short time by nitriding, which effectively reduces the formation of low-valence metal defects and improves charge separation efficiency. It exhibits water-splitting activity in photocatalytic water splitting reaction, and its activity is significantly improved compared with Ta3N5 prepared by conventional methods.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications and substitutions should be covered within the scope of the claims of this application.

Claims

1. A method for preparing a nitride Ta3N5, characterized by: The preparation method comprises the following steps: High temperature hydrolysis of precursor I gives amorphous product TaO x ; TaO x High temperature nitridation yields Ta3N5; The precursor I comprises ATaP2O8 and A3TaP2O9, and A is selected from K and Na.

2. The method of claim 1, wherein the method is characterized by: The high-temperature hydrolysis of the precursor I is performed at a temperature of 80-100 ℃ for 1-2 h.

3. The method for preparing nitride Ta3N5 as described in claim 2, characterized in that: The high-temperature hydrolysis of the precursor I comprises adding a 1-5 M AOH solution, wherein A is selected from K and Na.

4. The method of claim 1, wherein the method is characterized by: The ATaP2O8 is prepared by a high-temperature solid-phase method using an A precursor, a Ta precursor, a P precursor and an AP mixed precursor as raw materials, wherein the molar ratio of A, Ta, P and AP is 1:1:2:(0-10).

5. The method of claim 1, wherein the method is characterized by: The A3TaP2O9 is prepared by a high-temperature solid-phase method using an A precursor, a Ta precursor, a P precursor and an AP mixed precursor as raw materials, wherein the molar ratio of A, Ta, P and AP is 3:1:2:(0-10).

6. The method of producing nitride Ta3N5 according to claim 4 or 5, characterized by: The A precursor comprises at least one of a carbonate, an oxalate and a nitrate of A. The Ta precursor is Ta2O 5； The P precursor is NH4H2PO4 4； The AP mixed precursor includes H3PO4, AH2PO 4、 at least two of A2HPO4.

7. The method for preparing nitride Ta3N5 as described in claim 4, characterized in that: The high-temperature solid-phase method is performed at a temperature of 800-900 ℃ for 5-15 h.

8. The method of claim 1, wherein the method is characterized by: The high-temperature nitriding is performed in an ammonia gas flow of 200-300 mL / min at a temperature of 850-1000 ℃ for 3-10 h.

9. The nitride Ta3N5 prepared by the preparation method in any one of claims 1-8.

10. The nitride Ta3N5 in claim 8 is applied to photocatalytic oxygen production.

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