Preparation and application of two-dimensional cobalt-molybdenum ring cluster crystalline electrode material

Abstract

The invention relates to preparation and application of a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material. The invention aims to solve the problems of less application, poor stability and low catalytic performance of polyoxometallate serving as a catalytic material in the field of electro-catalysis of nitrate to synthesize ammonia. The chemical formula of the two-dimensional cobalt molybdenum ring cluster crystalline state electrode material disclosed by the invention is {(CoO6) (CoO5) 2 (CoO3) 2 [P24MoV16Co16O147]} 2.20 H2O. The synthesis method comprises the following steps: sequentially adding sodium molybdate, cobalt chloride and 1, 3-bis (1H-imidazole-1-yl) benzene into ethanol, distilled water and phosphoric acid, uniformly stirring, adjusting the pH value, and reacting for 3 days at the temperature of 180 DEG C to obtain the crystalline material, and the highest Faraday efficiency (FE) of the crystalline material for electrocatalytic reduction of nitrate to synthesize ammonia is 96.84%. And a feasible technical route is provided for constructing the two-dimensional cobalt-molybdenum ring cluster crystal to improve the electro-catalysis nitrate ammonia synthesis performance.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material having the property of electrocatalyzing nitrate reduction to synthesize ammonia. Background Art

[0002] Agricultural runoff and industrial wastewater contribute to the global concentration of nitrates (NO3 - ) pollution exceeds the standard, and traditional treatment technologies (such as reverse osmosis and biological denitrification) have problems such as high energy consumption and secondary pollution. At present, for most areas, it is urgent to treat the polluted water. Common nitrate nitrogen treatment methods include biological method, ion exchange method and electrocatalytic method. Among them, biological method is the most common technology for removing nitrate from water bodies. It uses microorganisms to convert NO3 - It is gradually reduced to N2: NO3- → NO2- → NO → N2O → N2 (denitrification pathway), but the residual N2O greenhouse gas accumulates as denitrification intermediates. The greenhouse effect of N2O is 265 times that of CO2. Electrocatalysis can convert NO3- into high-value-added ammonia (NH3), offering both environmental and economic benefits. Catalysts are key to improving their performance. Precious metal (Pt, Ru) catalysts are expensive and their scarcity restricts their large-scale application. Transition metal alloy (Cu-Co) catalysts have low selectivity (producing N2O and N2 as byproducts) and are easily deactivated under acidic conditions. Single-atom catalysts (Fe-NC) are complex to synthesize and have poor stability (<50 hours).

[0003] Polyoxometalates (POMs) (also known as polyoxometalates) are discrete multinuclear inorganic clusters formed by early transition metal ions (such as Mo, W, V, Nb, Ta, etc.) bridged by oxygen atoms. They belong to an important branch of metal oxoclusters (MOCs). Due to their highly regular structure and highly tunable performance, they have attracted much attention in the fields of chemistry, materials, energy, etc. They are composed of metal centers (such as W, Mo), bridging oxygen (μ2-O, μ3-O) and terminal oxygen (=O), and can contain heteroatoms (P, Si, B, As, etc.). They can maintain a discrete structure in aqueous solutions or organic solvents, have nanoscale sizes (1–3nm) and high negative charges (such as [P2W 18 O 62 ] 6– ), metal center (such as W 6+ / W 5+ 、Mo 6+ / Mo 5+ ) can undergo reversible electron transfer, making them suitable for electrocatalytic systems. However, polyoxometallic clusters have limited stability and are prone to decomposition under strong acidic or alkaline conditions. Structural manipulation or modification, such as the formation of multidimensional metal cluster crystalline materials by connecting transition metals (such as Co, Fe, and Ni), can enhance catalytic activity and stability.

[0004] Based on this, the present invention designs and develops a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material with the property of electrocatalytic nitrate reduction to ammonia synthesis, in the hope of solving the problems of low stability and electrocatalytic activity of nitrate reduction catalysts. By utilizing the coordination connection between reducing phosphomolybdic acid polyanions and active metal ions, a high-dimensional polymetallic oxygen cluster is constructed, which has good redox ability and high-density monodisperse metal active sites. Based on the above, we have prepared a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material with the property of electrocatalytic nitrate reduction to ammonia synthesis, providing a novel strategy for the preparation of electrocatalytic nitrate synthesis catalysts. Summary of the Invention

[0005] The present invention aims to address the poor stability and catalytic performance of polyoxometallic clusters as electrocatalytic nitrate reducing agents in solution. To improve their electrocatalytic performance, the present invention provides a method for preparing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material and its application for electrocatalytic nitrate reduction to ammonia synthesis.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] 1. Preparing a reaction solution with a pH of 1.8 to 2.5: adding ethanol, distilled water, and phosphoric acid to sodium molybdate, 1,3-bis(1H-imidazol-1-yl)benzene, and cobalt chloride in sequence, stirring uniformly, and adjusting the pH of the solution to 1.8 to 2.5 with NaOH and H3PO4 to obtain a reaction solution;

[0008] The molar ratio of sodium molybdate to cobalt chloride in step 1 is 1:(1.44-1.8);

[0009] The molar ratio of sodium molybdate to 1,3-bis(1H-imidazol-1-yl)benzene in step 1 is 14.8:1;

[0010] The molar ratio of sodium molybdate to ethanol, distilled water and phosphoric acid described in step 1 is 1:49:631:5.

[0011] 2. Preparation of a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material with electrocatalytic nitrate reduction to ammonia synthesis: Transfer the reaction solution prepared in step 1 to a 15mL polytetrafluoroethylene reactor and react at 180°C for 3 days. After cooling to room temperature, red diamond-shaped block crystals are obtained, i.e., a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material with electrocatalytic nitrate reduction to ammonia synthesis. The crystal appearance is red diamond-shaped block. The chemical formula of the substance is {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O147 ]}2·20H2O, the crystal system is monoclinic; the space group is P21 / n; the unit cell parameters are α=90°, β=99.6350(10), γ=90°,

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. This invention successfully prepared a cyclic cobalt-molybdenum cluster for the first time using 1,3-bis(1H-imidazol-1-yl)benzene organic ligand, cobalt chloride, and phosphomolybdic acid through a one-step hydrothermal synthesis method. Single crystal X-ray diffraction results show that the crystalline material prepared by this invention is a two-dimensional cobalt-molybdenum ring cluster crystalline material with the property of electrocatalytic nitrate reduction to synthesize ammonia. Its basic structural unit is PO4 3- and O 2- Sixteen hexacoordinated Co atoms and 16 pentacoordinated Mo atoms are connected to form a ring structure. Different structural units are connected by two metal Co atoms, and the staggered arrangement forms a two-dimensional planar structure.

[0014] Second, a two-dimensional cobalt-molybdenum ring cluster crystal with electrocatalytic nitrate reduction to ammonia synthesis, prepared in this embodiment, was used as an electrode material, achieving a maximum FE of 95.84%. This provides a technical route for constructing polymetallic oxygen clusters with ring-like network structures to enhance their catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an example of a basic structural unit diagram of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalytic nitrate reduction to synthesize ammonia.

[0016] Figure 2 For example, a is a schematic side view of the spatial staggered arrangement of cobalt molybdenum ring clusters, b is a schematic view of the arrangement of cobalt molybdenum ring clusters on the a-axis, c is a schematic view of the arrangement of cobalt molybdenum ring clusters on the b-axis, and d is a schematic view of the arrangement of cobalt molybdenum ring clusters on the c-axis.

[0017] Figure 3 This is an example of a three-dimensional stacking diagram of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalyzing nitrate reduction to synthesize ammonia.

[0018] Figure 4 This is an example of a powder X-ray diffraction pattern of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalyzing nitrate reduction to synthesize ammonia.

[0019] Figure 5 This is an example of an infrared spectrum of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalyzing nitrate reduction to synthesize ammonia.

[0020] Figure 6For example, a two-dimensional cobalt-molybdenum ring cluster with electrocatalytic nitrate reduction to ammonia was subjected to nitrate reduction to ammonia synthesis in a neutral electrolyte (0.1M Na2SO4 and 0.1M KNO3). Ultraviolet-visible absorption spectra (UV-vis) were obtained by measuring the electrolyte after a 1-h time-current (it) test at different voltages.

[0021] Figure 7 This is an example - a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalyzing nitrate reduction to synthesize ammonia, showing the ammonia production and Faraday efficiency at different voltages.

[0022] Figure 8 Case Study: A two-dimensional cobalt-molybdenum ring cluster with electrocatalytic nitrate reduction to ammonia in the presence or absence of NO 3- Current-potential (LSV) curve in electrolyte. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0024] Specific embodiment 1: This embodiment describes a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material with the property of electrocatalytic nitrate reduction to synthesize ammonia, the chemical formula of the material is {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O, its basic structural unit is PO4 3- and O 2- Sixteen hexacoordinated Co atoms and 16 pentacoordinated Mo atoms are connected to form a ring structure. Different basic structural units are connected by two metal Co atoms, and the basic units are staggered to form a two-dimensional planar structure.

[0025] Specific embodiment 2: The preparation method of a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material having the property of electrocatalyzing nitrate reduction to synthesize ammonia in this embodiment is completed by the following steps:

[0026] 1. Preparing a reaction solution with a pH of 1.8 to 2.5: First, add 10 mL of ethanol to 0.85 g of sodium molybdate, 0.05 g of 1,3-bis(1H-imidazol-1-yl)benzene, and 1.2 to 1.5 g of cobalt chloride, and stir for 10 minutes. Then, add 40 mL of distilled water, and stir for 10 minutes. Finally, add 1 mL of phosphoric acid, and stir for 20 minutes. Then, adjust the pH of the solution to 1.8 to 2.5 with NaOH and H3PO4 to obtain a reaction solution.

[0027] The molar ratio of sodium molybdate to cobalt chloride in step 1 is 1:(1.44-1.8);

[0028] The molar ratio of sodium molybdate to 1,3-bis(1H-imidazol-1-yl)benzene in step 1 is 14.8:1;

[0029] The molar ratio of sodium molybdate to ethanol, distilled water and phosphoric acid described in step 1 is 1:49:631:5.

[0030] 2. Preparation of a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material with electrocatalytic nitrate reduction to ammonia synthesis: The reaction solution prepared in step 1 was transferred to a 15 mL polytetrafluoroethylene reactor, reacted at 180°C for 3 days, and then gradually cooled. After the temperature dropped to room temperature, red rhombus block crystals were obtained, i.e., a two-dimensional cobalt-molybdenum ring cluster crystal with electrocatalytic nitrate reduction to ammonia synthesis properties. The crystal appearance is red block. The chemical formula of the substance is {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O, the crystal system is monoclinic; the space group is P21 / n; the unit cell parameters are α=90°, β=99.6350(10), γ=90°,

[0031] The cooling rate in step 2 is 10°C / h.

[0032] This embodiment is characterized in that in step 1, the pH value of the reaction solution is adjusted to 1.8-2.5 using an H3PO4 solution with a molar concentration of 1 mol / L and a NaOH solution with a molar concentration of 1 mol / L.

[0033] Specific embodiment 3: This embodiment differs from specific embodiment 2 in that the metal cobalt salt in step 1 is cobalt sulfate. Other aspects are the same as specific embodiments 1 to 3.

[0034] Specific embodiment 4: This embodiment differs from specific embodiment 2 in that the reaction temperature in step 2 is 170-200° C. and the reaction time is 3-5 days. The other steps are the same as those in specific embodiment 1.

[0035] The following examples are used to verify the beneficial effects of the present invention:

[0036] Example - A two-dimensional cobalt-molybdenum ring cluster with electrocatalytic nitrate reduction to ammonia synthesis is achieved by the following steps:

[0037] A reaction solution having a pH of 2 was prepared by first adding 10 mL of ethanol to 0.85 g of sodium molybdate, 0.05 g of 1,3-bis(1H-imidazol-1-yl)benzene, and 1.2 g of cobalt chloride, and stirring for 10 minutes. Then, 40 mL of distilled water was added, and stirring was performed for 10 minutes. Finally, 1 mL of phosphoric acid was added, and stirring was performed for 20 minutes. The pH of the solution was then adjusted to 2 with NaOH and H3PO4 to obtain a reaction solution.

[0038] The molar ratio of sodium molybdate to cobalt chloride in step 1 is 1:1.44;

[0039] The molar ratio of sodium molybdate to 1,3-bis(1H-imidazol-1-yl)benzene in step 1 is 14.8:1;

[0040] The molar ratio of sodium molybdate to ethanol, distilled water and phosphoric acid described in step 1 is 1:49:631:5.

[0041] Preparation of a two-dimensional cobalt-molybdenum ring cluster with electrocatalytic nitrate reduction to ammonia synthesis: The reaction solution prepared in step 1 was transferred to a 15 mL polytetrafluoroethylene reactor and reacted at 180°C for 3 days. After the temperature was lowered to room temperature, red rhombus-shaped block crystals were obtained, i.e., a two-dimensional cobalt-molybdenum ring cluster crystal with electrocatalytic nitrate reduction to ammonia synthesis.

[0042] 2. In the process of adjusting the pH value of the reaction solution to 2 in step 1, a 1 mol / L H3PO4 solution and a 1 mol / L NaOH solution are used for adjustment.

[0043] 3. The cooling rate described in step 2 is 10℃ / h

[0044] (1) Structural determination of a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material having the property of electrocatalyzing nitrate reduction to synthesize ammonia, prepared in Example 1:

[0045] Conclusion ①X-ray crystallography parameters: see Table 1.

[0046] Table 1 Crystallographic parameters of materials

[0047]

[0048] a R1=∑║F o │─│F c ║ / ∑│F o │. b wR2={∑[w(F o 2 ─F c 2 ) 2 ] / ∑[w(F o 2 ) 2 ]} 1 / 2

[0049] Conclusion②X-ray crystal structure description: X-ray single crystal diffraction analysis shows that

[0050] A two-dimensional cobalt-molybdenum ring cluster crystal with the property of electrocatalytic nitrate reduction to synthesize ammonia is monoclinic in the P21 / n space group. The unit cell parameters are α=90°, β=99.6350(10), γ=90°, The basic structural unit of the crystal includes PO4 3- and 16 hexacoordinated Co atoms and 16 pentacoordinated Mo atoms, as well as 20 free water molecules, by using PO4 3- and O 2- Connect Co atoms and Mo atoms to form a ring structure (such as Figure 1 shown).

[0051] Figure 1 This is an example - a diagram of the basic structural unit of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalytic nitrate reduction to synthesize ammonia.

[0052] Figure 2 For example, a is a schematic diagram of the spatial staggered arrangement of cobalt molybdenum ring clusters, b is a schematic diagram of the arrangement of cobalt molybdenum ring clusters on the a-axis, c is a schematic diagram of the arrangement of cobalt molybdenum ring clusters on the b-axis, and d is a schematic diagram of the arrangement of cobalt molybdenum ring clusters on the c-axis.

[0053] Figure 3 This is an example of a three-dimensional stacking diagram of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalyzing nitrate reduction to synthesize ammonia.

[0054] (II) Example - Preparation of a two-dimensional cobalt-molybdenum ring cluster crystal {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147]}2·20H2O was used for powder X-ray diffraction measurement to obtain a powder X-ray diffraction spectrum of a cobalt-molybdenum cluster coordination polymer. Figure 4 As shown, the peak positions of the experimentally measured spectrum are consistent with those of the spectrum obtained by crystal simulation. It can be determined that the crystal structure obtained by the experiment is the same as the structure analyzed by the software, and the purity of the crystal is very high.

[0055] Figure 4 This is the powder X-ray diffraction pattern of a two-dimensional cobalt-molybdenum ring cluster prepared in Example 1, which has the property of electrocatalyzing nitrate reduction to synthesize ammonia.

[0056] (III) Example - Preparation of a two-dimensional cobalt-molybdenum ring cluster {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O was characterized by infrared spectroscopy to obtain its infrared spectrum. Figure 5 As shown, at 1061, 955, 869 and 805 cm -1 The characteristic peaks are attributed to ν(PO), ν(Mo=Ot), ν(Mo-Ob-Mo) and ν(Mo-Oc-Mo) stretching vibrations; at 3444 cm -1 The characteristic peaks are attributed to the stretching vibration peaks of water molecules in the compound.

[0057] Figure 5 This is the infrared spectrum of a two-dimensional cobalt-molybdenum ring cluster with the property of electrocatalytic nitrate reduction to synthesize ammonia.

[0058] (IV) A two-dimensional cobalt-molybdenum ring cluster crystal {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O was used for electrochemical performance testing. Using a three-electrode system, in an electrolyte solution of (0.1M Na2SO4 and 0.1M KNO3), a carbon cloth electrode modified with the compound was used as the working electrode, a silver / silver chloride electrode was used as the reference electrode, and platinum was used as the counter electrode. After a 1h current-time (it) test at different voltages, the electrolyte solution was colorized and the UV-visible absorption spectrum was measured. Figure 6 It can be seen that as the applied voltage increases, the absorbance of the electrolyte that develops color after the electrocatalytic test in the absorbance test also gradually increases.

[0059] (V) A two-dimensional cobalt-molybdenum ring cluster crystal {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O in a neutral electrolyte (0.1M Na2SO4 and 0.1M KNO3) for nitrate reduction to ammonia, the ammonia yield and Faraday efficiency after 1 hour of testing at different voltages are shown in Figure 4. Figure 6 The ammonia production and Faraday efficiency of the two-dimensional cobalt-molybdenum ring cluster crystal with electrocatalytic nitrate reduction to ammonia synthesis properties at different voltages obtained from the data and electrochemical data. Figure 7 It can be seen that at a potential of -0.7 V vs. RHE, the highest Faradaic efficiency is 96.84%, and the corresponding ammonia production is 8.6 mg h –1 mg cat . -1 Therefore, the material can be used as an efficient electrocatalytic nitrate material.

[0060] In summary, the two-dimensional cobalt-molybdenum ring cluster crystal {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O was successfully prepared by a hydrothermal synthesis method as a material with the property of electrocatalytic reduction of nitrate to ammonia. This material has excellent redox properties and stability, and can be used as a material for electrocatalytic nitrate reduction to ammonia synthesis, with potential application value in this catalytic field.

Claims

1. A two-dimensional cobalt-molybdenum ring cluster crystalline electrode material has the chemical formula {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O; the crystal appearance is red rhombus; the crystal system is monoclinic; the space group is P21 / n; the unit cell parameters are α=90°, β=99.6350(10), γ=90°, 2. A two-dimensional cobalt-molybdenum ring cluster crystalline electrode material, characterized in that Different from the structure of other types of cobalt-molybdenum polymers, the basic structural unit is a ring structure, symmetrical up and down, and the basic structural unit is connected by PO4 3- and O 2- Sixteen hexacoordinated Co atoms and 16 pentacoordinated Mo atoms are connected to form a ring structure. Different basic structural units are connected by two Co atoms, and the basic units are staggered to form a two-dimensional planar structure.

3. A method for preparing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material is completed by the following steps:

1. Preparing a reaction solution with a pH of 1.8 to 2.5: First, add 10 mL of ethanol to 0.85 g of sodium molybdate, 0.05 g of 1,3-bis(1H-imidazol-1-yl)benzene, and 1.2 to 1.5 g of cobalt chloride, and stir for 10 minutes. Then, add 40 mL of distilled water, and stir for 10 minutes. Finally, add 1 mL of phosphoric acid, and stir for 20 minutes. Then, adjust the pH of the solution to 1.8 to 2.5 with NaOH and H3PO4 to obtain a reaction solution. The molar ratio of sodium molybdate to cobalt chloride in step 1 is 1:(1.44-1.8); The molar ratio of sodium molybdate to 1,3-bis(1H-imidazol-1-yl)benzene in step 1 is 14.8:1; The molar ratio of sodium molybdate to ethanol, distilled water and phosphoric acid described in step 1 is 1:49:631:

5.

2. Prepare a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material: Transfer the reaction solution prepared in step 1 to a 15 mL polytetrafluoroethylene reactor and react at a temperature of 180°C for 3 days. After the reaction solution temperature is lowered to room temperature, it is washed to obtain red rhombus block crystals, i.e., a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material. The crystal chemical formula of step 2 is {(CoO6)(CoO5)2(CoO3)2[P 24 Mo V 16 Co 16 O 147 ]}2·20H2O; the crystal appearance is red block; the crystal system is monoclinic; the space group is P21 / n; the unit cell parameters are α=90°, β=99.6350(10), γ=90°, 4. The method for preparing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3, characterized in that The cobalt chloride described in step 1 can be replaced by cobalt sulfate.

5. The method for preparing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3, characterized in that The molar ratio of 1,3-bis(1H-imidazol-1-yl)benzene, sodium molybdate, and cobalt chloride described in step 1 is 15:1:(21-26). At the same time, the structural formula of the organic ligand 1,3-bis(1H-imidazol-1-yl)benzene described in step 1 is:

6. The method for synthesizing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3, characterized in that The volume ratio of the molar number of sodium molybdate described in step 1 to distilled water is 3.52 mol:40 mL.

7. The method for synthesizing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3, characterized in that In step 1, the pH value of the reaction solution is adjusted to 1.8-2.5 using a 1 mol / L H3PO4 solution and a 1 mol / L NaOH solution.

8. The method for preparing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3, characterized in that The reaction temperature in step 2 is 170-200° C. and the reaction time is 3-5 days.

9. The method for preparing a two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3, characterized in that The cooling rate in step 2 is 10°C / h.

10. Use of the two-dimensional cobalt-molybdenum ring cluster crystalline electrode material according to claim 3 in the electrocatalytic synthesis of ammonia from nitrate at room temperature and pressure.

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