In-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia preparation catalyst and preparation method and application thereof

Abstract

The invention discloses an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia preparation catalyst as well as a preparation method and application thereof, and relates to the technical field of catalysts. The method comprises the following steps: stirring and dissolving a copper source and citrate in deionized water, then adding potassium ferricyanide, uniformly mixing, standing for 12-36 hours, then collecting a precipitate after standing, and washing and vacuum-drying the precipitate to prepare a Cu2 [Fe (CN) 6] precursor; and calcining the Cu2 [Fe (CN) 6] precursor in a mixed atmosphere of hydrogen and inert gas at 700-900 DEG C for 1-4 hours to obtain the catalyst for reducing CuFe-G nitrate to prepare ammonia. According to the prepared CuFe-G catalyst, due to alloying energy band modulation, spontaneous conversion from NO3 <-> to NO2 <-> is started, meanwhile, a stable CuFeOx ultrathin layer is formed along with surface reconstruction, and dynamic evolution is not needed. The stable CuFeOx ultrathin layer can optimize adsorption of key intermediate products and catalyze reduction of NO3 <-> and NO2 <-> in series, so that the reduction potential range of the nitrate is widened, and meanwhile, the Faraday efficiency of ammonia production through reduction of the nitrate is improved.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia production catalyst and a preparation method and application thereof. Background Art

[0002] The traditional Haber-Bosch route to produce ammonia would cause huge energy consumption and environmental crisis. 3 - To NH 3 The electrochemical conversion of NO is considered a promising alternative to the Haber-Bosch route. 3 − 、*NO 2 − , *NO and other intermediate species have good adsorption capacity, so in NO 3 - To NH 3 Cu-based electrocatalytic systems have great potential in the catalytic conversion of nitrates. However, when the Cu-based electrocatalytic system is powered by intermittent renewable energy (such as solar energy, wind energy, etc.), the fluctuation of the potential will cause the reaction conditions on the catalyst surface to change. This change may interfere with the active sites of the catalyst, making the originally efficient electrocatalytic reaction unstable, resulting in a decrease in the Faradaic efficiency. The reduction in Faradaic efficiency means that more electrical energy is consumed by non-target reactions, reducing the catalytic efficiency and selectivity of the catalyst, and ultimately affecting the overall performance of the electrocatalytic process. Therefore, how to reduce the impact of potential fluctuations on catalyst performance through reasonable material design is the key and main challenge to improving the nitrate reduction to ammonia production of Cu-based materials. Summary of the invention

[0003] In view of the deficiencies in the above-mentioned background technology, the present invention mainly solves the problem that the Faraday efficiency of nitrate reduction to ammonia is reduced due to the fluctuation of intermittent renewable energy in the existing Cu-based catalyst. The present invention provides an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction to ammonia catalyst and its preparation method and application. The method successfully constructs a CuFe-G catalyst through reasonable material design, and benefits from the band modulation of alloying, which starts the process of NO reduction. 3 - to NO 2 - The spontaneous transformation of CuFeO x Ultra-thin layers without dynamic evolution. Stable CuFeO x Ultra-thin layers can optimize the adsorption of key intermediates and catalyze NO in series 3 - and NO 2 -Reduction, thereby broadening the potential range of nitrate reduction, and at the same time improving the Faraday efficiency of nitrate reduction to ammonia. The prepared catalyst can electrocatalyze nitrate reduction to ammonia in a wide potential range, and the catalyst prepared by this method has the characteristics of low load, high activity and strong durability.

[0004] The first object of the present invention is to provide a method for preparing an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst, comprising the following steps: The copper source and citrate were stirred and dissolved in deionized water, and potassium ferrocyanide was added, mixed evenly, and allowed to stand for 12 to 36 hours. The precipitate was then collected, washed, and vacuum dried to obtain Cu 2 [Fe(CN) 6 ]precursor; Cu 2 [Fe(CN) 6 The precursor is calcined at 700-900°C for 1-4h in a mixed atmosphere of hydrogen and inert gas to obtain the CuFe-G nitrate reduction catalyst for ammonia production.

[0005] Preferably, the heating rate during calcination is 2-10 °C min -1 .

[0006] Preferably, the molar ratio of the copper source to the citrate is 1:1-3.

[0007] Preferably, the copper source is one or more of copper nitrate, copper chloride and copper sulfate.

[0008] Preferably, the citrate is one or more of sodium citrate and potassium citrate.

[0009] Preferably, the molar ratio of the copper source to potassium ferrocyanide is 1:1-3.

[0010] Preferably, in the mixed atmosphere of hydrogen and inert gas, the hydrogen accounts for 5% of the volume ratio; and the gas rate of the mixed atmosphere is 10-100 sccm.

[0011] Preferably, the vacuum drying temperature is 40-80° C., and the drying time is 4-12 h.

[0012] The second object of the present invention is to provide an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction catalyst for ammonia production.

[0013] The third object of the present invention is to provide an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction to ammonia catalyst for use in electrocatalytic nitrate reduction to ammonia.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia production catalyst and a preparation method and application thereof. The present invention converts K in potassium ferrocyanide into ammonia by an impregnation method. + Substituted and replaced by Cu 2+ , successfully obtained Cu 2 [Fe(CN) 6 ] precursor, followed by thermal treatment to optimize the catalyst's crystal structure and Surface active sites were obtained to obtain a CuFe bimetallic catalyst supported on graphene Garphene.

[0015] The advantages of the catalyst provided by the present invention are reflected in the following aspects.

[0016] (1) High catalytic activity sites: Thanks to the energy band modulation of alloying, CuFe-G initiates the conversion of NO 3 - to NO 2 - The spontaneous transformation of CuFeO x Ultra-thin layers without dynamic evolution. Stable CuFeO x Ultra-thin layers can optimize the adsorption of key intermediates and catalyze NO in series 3 - and NO 2 - In addition, the graphene Garphene carrier can promote the transfer of electrons in the process of nitrate reduction to produce ammonia and accelerate the reaction kinetics.

[0017] (2) Broadened potential range: Thanks to the energy band modulation of alloying, CuFe-G initiates the transition from NO 3 - to NO 2 - The spontaneous transformation of CuFeO x Ultra-thin layers without dynamic evolution. Stable CuFeO x The ultra-thin layer can maintain the reaction conditions on the catalyst surface, ensuring that the active sites of the catalyst are fully involved in the reduction of nitrate to produce ammonia, thereby achieving efficient ammonia production over a wide potential range.

[0018] (3) Excellent stability: The CuFe-G nitrate reduction catalyst exhibits excellent cyclic stability under neutral nitrate reduction conditions, ensuring its reliability for long-term use.

[0019] (4) Low cost and easy preparation: Cu-based catalysts are low-cost, and the preparation process of CuFe-G nitrate reduction catalyst for ammonia production is relatively simple, which has good industrial application prospects.

[0020] In addition, the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction catalyst for ammonia production in neutral electrolyte has the characteristics of efficient and stable ammonia production in a wide potential range. It exhibits a Faradaic efficiency of more than 95% for electrocatalytic nitrate reduction to ammonia production in a wide potential range of -0.7 V ~ -1.0 V vs. RHE, and achieves 8.03 mgh at -1.0 V vs. RHE. -1 mg cat -1 NH 3 The in-situ spontaneous surface reconstruction method of the CuFe-G nitrate reduction ammonia production catalyst of the present invention has a simple preparation process, low cost, low equipment investment, high controllability, mild reaction conditions, small footprint and environmental friendliness, and is used in the field of nitrate reduction ammonia production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The Cu prepared in Example 1 2 [Fe(CN) 6 ]X-ray diffraction pattern of the precursor; Figure 2 The Cu prepared in Example 1 2 [Fe(CN) 6 ]SEM image of the precursor; Figure 3 The X-ray diffraction pattern of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Figure 4 The transmission electron microscope image of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Figure 5 This is a high-resolution transmission electron microscopy image of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Figure 6 The linear sweep voltammogram of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Figure 7 This is a Faraday efficiency diagram of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Figure 8 This is a graph showing the ammonia yield of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Fig. 9 This is a cyclic stability diagram of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1; Fig.10 This is a transmission electron microscopy image of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1 after in-situ spontaneous surface reconstruction; Fig.11 This is a graph showing the ammonia yield of the CuFe-G-1 nitrate reduction catalyst for ammonia production prepared in Example 2; Fig.12 This is a graph showing the ammonia yield of the CuFe-G-2 nitrate reduction catalyst for ammonia production prepared in Example 3; Fig.13 This is a graph showing the ammonia yield of the CuFe-G-3 nitrate reduction catalyst for ammonia production prepared in Example 4. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0023] The purpose of the present invention is to provide an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia production catalyst and its preparation method and application, so as to solve the problem that the Faraday efficiency of nitrate reduction to ammonia production of existing Cu-based catalysts is reduced due to intermittent renewable energy fluctuations. The influence of potential fluctuations on catalyst performance is mainly reduced through reasonable material design, thereby achieving efficient ammonia production in a wide potential range.

[0024] In order to achieve the above object, the first aspect of the present invention provides a method for preparing an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst, comprising the following steps: The copper source and citrate were stirred and dissolved in deionized water, and potassium ferrocyanide was added, mixed evenly, and allowed to stand for 12 to 36 hours. The precipitate was then collected, washed, and vacuum dried to obtain Cu 2 [Fe(CN) 6 ]precursor; Cu 2 [Fe(CN) 6 The precursor is calcined at 700-900°C for 1-4h in a mixed atmosphere of hydrogen and inert gas to obtain the CuFe-G nitrate reduction catalyst for ammonia production.

[0025] The heating rate during calcination is 2~10 ℃ min -1 .

[0026] The molar ratio of the copper source to the citrate is 1:1-3.

[0027] The copper source is one or more of copper nitrate, copper chloride and copper sulfate.

[0028] The citrate is one or more of sodium citrate and potassium citrate.

[0029] The molar ratio of the copper source to potassium ferrocyanide is 1:1-3.

[0030] In a mixed atmosphere of hydrogen and inert gas, the hydrogen accounts for 5% of the volume ratio; and the gas rate of the mixed atmosphere is 10-100 sccm.

[0031] The vacuum drying temperature is 40-80°C, and the drying time is 4-12 hours.

[0032] Exemplarily, a method for preparing an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst comprises: Step 1: Cu 2 [Fe(CN) 6 ]Preparation of precursor: First, the copper source and citrate were stirred and dissolved in deionized water, then potassium ferrocyanide was added to the mixed solution and fully dissolved, and then the solution was allowed to stand for 12 to 36 hours to promote the reaction. The supernatant was then removed by decantation, and the precipitate at the bottom was collected and washed with deionized water and vacuum dried to successfully obtain Cu 2 [Fe(CN) 6 ]precursor.

[0033] Step 2: Cu 2 [Fe(CN) 6 ] The precursor was in 5% H 2 / Ar atmosphere, 2~10 ℃ min -1 The mixture was calcined at different temperatures for 1 to 4 h and then naturally cooled to room temperature to obtain a CuFe-G nitrate reduction catalyst for ammonia production.

[0034] The copper source described in step 1 is one or more of copper nitrate, copper chloride, and copper sulfate.

[0035] The citrate described in step 1 is one or more of sodium citrate and potassium citrate.

[0036] The molar ratio of the copper source and the citrate in step 1 is 1:1-3.

[0037] The stirring described in step 1 is stirring at a rotation speed of 60 to 600 rpm for 5 to 60 minutes.

[0038] In the mixed solution described in step 1, the copper source concentration is 0.005~0.5 mol L -1 , citrate concentration is 0.005~1.5 mol L -1 .

[0039] The molar ratio of the copper source and potassium ferrocyanide described in step 1 is 1:1-3.

[0040] The number of deionized water washings described in step 1 is 2 to 5 times.

[0041] The vacuum drying temperature described in step 1 is 40~80°C, and the drying time is 4~12 h.

[0042] H described in step 2 2 The gas flow rate of Ar / Ar is 10~100 sccm.

[0043] The different temperatures described in step 2 are 750, 800, 850, and 900°C.

[0044] The second aspect of the present invention provides an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction catalyst for ammonia production. The catalyst uses graphene as a carrier, and CuFe bimetallic alloy clusters are loaded on graphene (G).

[0045] A third aspect of the present invention provides an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction to ammonia catalyst application in electrocatalytic nitrate reduction to ammonia.

[0046] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0047] Example 1 A method for preparing an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst is carried out according to the following steps: Step 1: Cu 2 [Fe(CN) 6 ]Precursor preparation: First, 4 mmol copper (II) nitrate trihydrate (Cu(NO 3 ) 2 ·3H 2 O) and 9 mmol sodium citrate were stirred and dissolved in 50 ml deionized water, and then 6 mmol potassium ferrocyanide (K 3 [Fe(CN) 6 ]) and fully dissolved, and then the solution was allowed to stand for 24 hours to promote the reaction. The supernatant was then removed by decantation, and the precipitate at the bottom was collected and washed three times with deionized water and dried in vacuum at 60 °C for 6 h. Cu 2 [Fe(CN) 6 ]precursor.

[0048] Step 2: Cu 2 [Fe(CN) 6 ] The precursor was in 5% H 2 / Ar atmosphere, with a ventilation rate of 30 sccm and 5 ℃min -1 The mixture was calcined at 850 ℃ for 2 h with a heating rate of , and then naturally cooled to room temperature to obtain a CuFe-G nitrate reduction catalyst for ammonia production.

[0049] Figure 1 The Cu prepared in step 1 of this embodiment 1 2 [Fe(CN) 6 ] The X-ray diffraction pattern of the precursor, combined with the XRDPDF standard card, proves that Cu 2 [Fe(CN) 6 ]Successful synthesis of the precursor.

[0050] Figure 2 The Cu prepared in step 1 of this embodiment 1 2 [Fe(CN) 6 ]Scanning electron microscope image of the precursor, the synthesized precursor Cu 2 [Fe(CN) 6 ] shows a cubic morphology.

[0051] Figure 3 This is an X-ray diffraction diagram of the CuFe-G nitrate reduction catalyst for ammonia production prepared in step 2 of this embodiment 1. The components of the CuFe-G nitrate reduction catalyst for ammonia production are nanoparticles of Cu and nanoparticles of Fe.

[0052] Figure 4 This is a transmission electron micrograph of the CuFe-G nitrate reduction catalyst for ammonia production prepared in step 2 of Example 1. The synthesized CuFe-G has a nanosphere morphology with an average diameter of about 150 nm and a spherical shell thickness of 25 nm.

[0053] Figure 5 This is a high-resolution transmission electron microscopy image of the CuFe-G nitrate reduction catalyst for ammonia production prepared in step 2 of Example 1. The lattice spacings of 0.34 nm and 0.204 nm correspond to the (002) crystal plane of graphene and the (110) crystal plane of the CuFe alloy, respectively.

[0054] Figure 6 Linear sweep voltammogram of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1. Electrocatalyst ink was prepared using the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1. 5 mg of the electrocatalyst was dispersed in a mixed solution of 500 μL deionized water, 450 μL ethanol, and 50 μL 5 wt.% Nafion solution. 25 μL of the electrocatalyst ink was coated on carbon paper (0.5 cm*0.5 cm). Carbon paper, Pt sheet, and Ag / AgCl (0.5 MK 2SO 4 + 0.1 M KNO 3 ) were used as working electrode, counter electrode and reference electrode, respectively, and connected to Chenhua 760e electrochemical workstation. Linear sweep voltammetry (LSV) curves were recorded in the potential window of 0.2 V to -0.4 V, with a scan rate of 5 mV s relative to the reversible hydrogen electrode (RHE). -1 , and has iR compensation. CuFe-G achieves 35.16 mA cm at a potential of −0.3 V vs. RHE. -2 of current density.

[0055] Figure 7 This is the Faraday efficiency diagram of the CuFe-G nitrate reduction catalyst for ammonia prepared in Example 1. In the potential range of -0.7 V to -1.0 V vs. RHE, the Faraday efficiency of CuFe-G was recorded as 99.78±4.73%, 98.66±4.17%, 97.91±3.51% and 99.63±2.94%. These high efficiencies, which are always over 95%, highlight the excellent performance of electrocatalytic nitrate reduction ammonia production in a wide potential window.

[0056] Figure 8 The ammonia yield of the CuFe-G nitrate reduction catalyst prepared in Example 1 is shown in FIG. In the potential range of -0.7 V to -1.0 V vs. RHE, the NH 3 The yield was 4.50 ± 0.69 mg h -1 mg cat -1 , 5.25±0.91 mg h -1 mg cat -1 , 6.04±0.65 mg h -1 mg cat -1 , 8.03±0.67 mg h -1 mg cat -1 .

[0057] Fig. 9 This is a cyclic stability diagram of the CuFe-G nitrate reduction catalyst for ammonia prepared in Example 1. Even after seven cycles and a cumulative total of 70 h, its Faradaic efficiency remains above 95%, which highlights the excellent catalytic stability of CuFe-G.

[0058] Fig.10 This is a transmission electron microscopy image of the CuFe-G nitrate reduction catalyst for ammonia production prepared in Example 1 after in-situ spontaneous surface reconstruction. 3- To NO 2 - During the spontaneous transformation of CuFeO, a stable CuFeO x Ultra-thin layer.

[0059] Example 2 A method for preparing a CuFe-G-1 nitrate reduction catalyst for ammonia production is carried out according to the following steps: Step 1: Cu 2 [Fe(CN) 6 ]The preparation process of the precursor is the same as that in Example 1.

[0060] Step 2: Cu 2 [Fe(CN) 6 ] The precursor was in 5% H 2 / Ar atmosphere, with a ventilation rate of 30 sccm and 5 ℃min -1 The mixture was calcined at 700 °C for 2 h with a heating rate of , and then naturally cooled to room temperature to obtain CuFe-G-1 nitrate reduction catalyst for ammonia production.

[0061] Fig.11 This is a graph showing the ammonia yield of the CuFe-G-1 nitrate reduction catalyst prepared in Example 2. At a potential of -1.0 V vs. RHE, NH 3 The yield was 5.09 mg h -1 mg cat -1 .

[0062] Example 3 A method for preparing a CuFe-G-2 nitrate reduction ammonia catalyst is carried out according to the following steps: Step 1: Cu 2 [Fe(CN) 6 ]The preparation process of the precursor is the same as that in Example 1.

[0063] Step 2: Cu 2 [Fe(CN) 6 ] The precursor was in 5% H 2 / Ar atmosphere, with a ventilation rate of 30 sccm and 5 ℃min -1 The mixture was calcined at 800 °C for 2 h at a heating rate of , and then naturally cooled to room temperature to obtain CuFe-G-2 nitrate reduction catalyst for ammonia production.

[0064] Fig.12 This is a graph showing the ammonia yield of the CuFe-G-2 nitrate reduction catalyst prepared in Example 3. At a potential of -1.0 V vs. RHE, NH 3The yield was 7.42 mg h -1 mg cat -1 .

[0065] Example 4 A method for preparing a CuFe-G-3 nitrate reduction catalyst for ammonia production is carried out according to the following steps: Step 1: Cu 2 [Fe(CN) 6 ]The preparation process of the precursor is the same as that in Example 1.

[0066] Step 2: Cu 2 [Fe(CN) 6 ] The precursor was in 5% H 2 / Ar atmosphere, with a ventilation rate of 30 sccm and 5 ℃min -1 The mixture was calcined at 900 °C for 2 h at a heating rate of , and then naturally cooled to room temperature to obtain CuFe-G-3 nitrate reduction catalyst for ammonia production.

[0067] Fig.13 This is a graph showing the ammonia yield of the CuFe-G-3 nitrate reduction catalyst prepared in Example 4. At a potential of -1.0 V vs. RHE, NH 3 The yield was 6.18 mg h -1 mg cat -1 .

[0068] In summary, the present invention provides a method for preparing and applying a CuFe-G catalyst for nitrate reduction to ammonia production by spontaneous surface reconstruction in situ. The method mainly solves the problem that the Faraday efficiency of existing Cu-based catalysts for nitrate reduction to ammonia production is reduced due to intermittent fluctuations in renewable energy. First, CuFe-G catalysts were synthesized by impregnation. 2 [Fe(CN) 6 ] precursor, and then Cu 2 [Fe(CN) 6 The CuFe-G catalyst for nitrate reduction to ammonia was obtained by heat treatment of the precursor. The prepared CuFe-G catalyst benefited from the energy band modulation of alloying, which initiated the process of NO reduction. 3 - to NO 2 - The spontaneous transformation of CuFeO x Ultra-thin layers without dynamic evolution. Stable CuFeO x Ultra-thin layers can optimize the adsorption of key intermediates and catalyze NO in series 3 - and NO 2 -Reduction, thereby broadening the nitrate reduction potential range and improving the Faradaic efficiency of nitrate reduction to ammonia.

[0069] The present invention describes preferred embodiments and their effects. However, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst, characterized in that: The following steps are involved: The copper source and citrate are stirred and dissolved in deionized water, and potassium ferrocyanide is added, mixed evenly, and allowed to stand for 12 to 36 hours, and then the precipitate after standing is collected, and the precipitate is washed and vacuum dried to obtain a Cu2[Fe(CN)6] precursor; The Cu2[Fe(CN)6] precursor is calcined at 700-900°C for 1-4h in a mixed atmosphere of hydrogen and inert gas to obtain a CuFe-G nitrate reduction catalyst for ammonia production.

2. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: The heating rate during calcination is 2~10 ℃ min -1 .

3. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: The molar ratio of the copper source to the citrate is 1:1-3.

4. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: The copper source is one or more of copper nitrate, copper chloride and copper sulfate.

5. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: The citrate is one or more of sodium citrate and potassium citrate.

6. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: The molar ratio of the copper source to potassium ferrocyanide is 1:1-3.

7. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: In a mixed atmosphere of hydrogen and inert gas, the hydrogen accounts for 5% of the volume ratio; and the gas rate of the mixed atmosphere is 10-100 sccm.

8. The method for preparing the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia catalyst according to claim 1, characterized in that: The vacuum drying temperature is 40-80°C, and the drying time is 4-12 hours.

9. An in-situ spontaneous surface reconstruction CuFe-G nitrate reduction ammonia production catalyst prepared by the method according to any one of claims 1 to 8.

10. Use of the in-situ spontaneous surface reconstruction CuFe-G nitrate reduction to ammonia catalyst according to claim 9 in electrocatalytic nitrate reduction to ammonia.

Images