Dimethyl pyridine amine copper complex, preparation method and application of dimethyl pyridine amine copper complex in photocatalytic ammoxidation
By preparing a copper complex of dimethylpyridinium amine for photocatalytic ammonia oxidation, the problem of poor catalyst performance was solved, and the stable generation of nitrogen and hydrazine intermediates was achieved, thus constructing an efficient energy conversion chain and improving the efficiency and selectivity of photocatalytic ammonia oxidation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEST UNIV
- Filing Date
- 2026-01-21
- Publication Date
- 2026-04-28
AI Technical Summary
Existing photocatalytic ammonia oxidation catalysts have poor catalytic performance, and the electrocatalytic process requires a high overpotential, which limits their economic viability in large-scale energy conversion.
A copper complex of dimethylpyridinium amine was prepared by reacting raw material A and dimethylpyridinium amine in an organic solvent at a molar ratio of 1-2:1-2 at room temperature, filtering and drying, and the resulting complex was used for photocatalytic ammonia oxidation.
The generation of nitrogen gas during photocatalytic ammonia oxidation was achieved, and the stable generation of hydrazine intermediate was detected. An efficient ammonia-photocatalysis-hydrazine energy conversion chain was constructed, avoiding additional power conversion losses and improving the selectivity and efficiency of the reaction.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a dimethylpyridineamine copper complex, its preparation method, and its application in photocatalytic ammonia oxidation. Background Technology
[0002] Ammonia (NH3), as a high-hydrogen (H) carrier, is widely used in the energy field, and significant progress has been made in electrocatalytic ammonia oxidation. For example, the low-coordination β-diketone imine copper complex developed by Ahmed et al. can efficiently catalyze the oxidation of ammonia to N2 and H2 in acetonitrile. However, the electrocatalytic process usually requires a high overpotential (generally exceeding 700 mV) and depends on an external power source, which greatly limits its economic viability in large-scale energy conversion.
[0003] In contrast, photocatalytic ammonia oxidation technology exhibits unique advantages. Photocatalytic ammonia oxidation is a green process that converts ammonia (NH3) into nitrogen (N2) under light irradiation. In recent years, it has received widespread attention due to its potential in clean energy conversion and nitrogen cycle management. The photocatalytic pathway demonstrates unique advantages and practical application value worthy of in-depth exploration. Although photocatalytic ammonia oxidation is still in its early stages of development, and its catalytic efficiency and system stability still have room for improvement, its unique ability to achieve the directional conversion of ammonia into nitrogen and hydrazine has shown great development potential. Therefore, developing a highly efficient and stable earth-abundant metal photocatalyst, optimizing the separation and utilization efficiency of photogenerated carriers, and promoting photocatalytic ammonia oxidation from basic research to practical applications can provide new technological solutions for sustainable energy and environmental protection. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a dimethylpyridineamine copper complex, its preparation method and its application in photocatalytic ammonia oxidation, so as to solve the technical problem of poor catalytic performance of photocatalytic ammonia oxidation catalysts.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing a dimethylpyridinamide copper complex is provided, comprising the following steps: raw material A and dimethylpyridinamide are mixed and dissolved in an organic solvent at a molar ratio of 1-2:1-2, reacted at room temperature for 2-6 hours, filtered, and the filtrate is dried to obtain the dimethylpyridinamide copper complex; raw material A is copper chloride, cuprous chloride, cuprous bromide, cuprous iodide or cuprous thiocyanate.
[0006] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the organic solvent is acetonitrile, tetrahydrofuran, methanol, or dichloromethane.
[0007] Furthermore, the drying temperature is room temperature, and the time is 22-26 hours.
[0008] The present invention also discloses a dimethylpyridineamine copper complex prepared by the above preparation method.
[0009] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the structural formula of the dimethylpyridinamine copper complex is as follows: , , , or .
[0010] The present invention also discloses the application of the above-mentioned dimethylpyridineamine copper complex in photocatalytic ammonia oxidation.
[0011] The beneficial effects of this invention are as follows: 1. This invention designs and synthesizes novel monovalent copper complexes containing chloride ions and confirms their excellent photocatalytic activity. Through photocatalytic ammonia oxidation experiments, not only was the final product nitrogen (N2) successfully detected, but the stable formation of the hydrazine (N2H4) intermediate was also directly detected in the reaction solution. This discovery provides strong and direct experimental evidence for the hypothetical reaction pathway of "copper-amide intermediate undergoing bimolecular coupling to generate hydrazine," especially under photocatalytic conditions, providing a crucial link in understanding and refining the entire catalytic cycle. By utilizing the dimethylpyridinamine copper complex prepared by this invention to store excess renewable energy in the form of ammonia and converting it into higher energy-density hydrazine through a photocatalytic process, a highly efficient "ammonia-photocatalysis-hydrazine" energy conversion chain can be constructed.
[0012] 2. Unlike electrocatalysis, which relies on an external power source to generate high overpotentials, photocatalysis directly utilizes photon energy to drive the reaction, avoiding additional energy conversion losses. This wavelength-specific excitation method not only facilitates the targeted activation of the catalyst but also effectively suppresses side reactions and improves reaction selectivity. Experiments have shown that under 450nm illumination, the dimethylpyridinamine copper complex prepared in this invention, when used as a catalyst, can efficiently absorb light energy and generate active intermediates, providing the driving force for the reaction. Attached Figure Description
[0013] Figure 1 The crystal structure diagram of the product Cu(Ⅰ)-Cl prepared in Example 1 is shown. Figure 2 Crystal structure diagram of Cu(Ⅰ)-Br prepared in Example 2; Figure 3 The crystal structure diagram of the product Cu(Ⅰ)-I prepared in Example 3 is shown. Figure 4The crystal structure diagram of Cu(Ⅰ)-SCN prepared in Example 4 is shown. Figure 5 Crystal structure diagram of Cu(II)-Cl2 prepared in Example 5; Where C1-C13 represent carbon atoms with ordinal numbers 1-13, N1-N4 represent nitrogen atoms with ordinal numbers 1-4, Br1 represents bromine atom with ordinal number 1, I1 represents iodine atom with ordinal number 1, S1 represents sulfur atom with ordinal number 1, Cl1 and Cl2 represent chlorine atoms with ordinal numbers 1 and 2 respectively, and Cu1 represents copper atom with ordinal number 1. Figure 6 For the preparation of product Cu(Ⅰ)-Cl in Example 1 1 H NMR spectrum; Figure 7 For the preparation of product Cu(Ⅰ)-Br in Example 2 1 H NMR spectrum; Figure 8 For the preparation of product Cu(Ⅰ)-I in Example 3 1 H NMR spectrum; Figure 9 For the preparation of product Cu(Ⅰ)-SCN in Example 4 1 H NMR spectrum; Figure 10 The IR spectrum of the product Cu(Ⅰ)-Cl prepared in Example 1; Figure 11 The IR spectrum of the product Cu(Ⅰ)-Br prepared in Example 2; Figure 12 The IR spectrum of the product Cu(Ⅰ)-I prepared in Example 3; Figure 13 The IR spectrum of the product Cu(Ⅰ)-SCN prepared in Example 4; Figure 14 The IR spectrum of the product Cu(II)-Cl2 prepared in Example 5; Figure 15 The gas chromatographic TCD signal images are shown before and after the Cu(Ⅰ)-Cl photocatalytic reaction. Figure 16 The gas chromatographic TCD signal images are shown before and after the Cu(Ⅰ)-Br photocatalytic reaction. Figure 17 The gas chromatographic TCD signal images are shown before and after the Cu(Ⅰ)-I photocatalytic reaction. Figure 18 The gas chromatographic TCD signal images are shown before and after the Cu(Ⅰ)-SCN photocatalytic reaction. Figure 19 This is the standard curve for the H2 gas phase. Figure 20This is the standard curve for the O2 gas phase. Figure 21 This is the standard curve for N2 gas phase; Figure 22 The value of N2H4 was detected after Cu(Ⅰ)-Cl 0.12M NH3CH3CN was irradiated for 1 h. Figure 23 The value of N2H4 after Cu(Ⅰ)-Cl 2.48M NH3CH3CN is irradiated for 1 h. Figure 24 The value of N2H4 was detected after Cu(Ⅰ)-Br 0.12M NH3CH3CN was irradiated for 1 h. Figure 25 The value of N2H4 after Cu(Ⅰ)-Br 2.48M NH3CH3CN is irradiated for 1 h. Figure 26 The value of N2H4 was detected after Cu(Ⅰ)-I 0.12M NH3CH3CN was irradiated for 1 h. Figure 27 The value of N2H4 was detected after Cu(Ⅰ)-I 2.48M NH3CH3CN was irradiated for 1 h. Figure 28 The value of N2H4 was detected after Cu(Ⅰ)-SCN 0.12M NH3CH3CN was irradiated for 1 h. Figure 29 The value of N2H4 was detected after Cu(Ⅰ)-SCN 2.48M NH3CH3CN was irradiated for 1 h. Figure 30 This is the standard curve for hydrazine; Figure 31 This is the standard curve for nitrate. Figure 32 This is the standard curve for nitrite. Figure 33 This is the standard curve for ammonium ions; Figure 34 This is the standard curve for hydroxylamine. Detailed Implementation
[0014] The specific embodiments of the present invention are described below to facilitate understanding of the invention by those skilled in the art. Unless otherwise specified, specific conditions are applied according to conventional conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims. All inventions utilizing the concept of this invention are protected.
[0015] Example 1 A method for preparing a ruthenium-amine complex includes the following steps: cuprous chloride (4.5 mmol) and dimethylpyridinamide (4.5 mmol) are mixed and dissolved in 50 mL of acetonitrile. After stirring evenly, the mixture is reacted at room temperature for 4 h, resulting in the precipitation of a yellow precipitate. The precipitate is filtered, and then washed successively with acetonitrile (2 mL), diethyl ether (3 mL × 3), and n-hexane (3 mL × 3). Finally, the mixture is dried at room temperature for 24 h to obtain a yellow powder, namely the dimethylpyridinamide copper complex (Cu(Ⅰ)-Cl), with a yield of 84.28%.
[0016] Example 2 The difference between this embodiment and Example 1 is that cuprous chloride is replaced with cuprous bromide, while the other conditions are the same as in Example 1, resulting in a dimethylpyridinamine copper complex (Cu(I)-Br) with a yield of 86.84%.
[0017] Example 3 The difference between this embodiment and Example 1 is that cuprous chloride is replaced with cuprous iodide, and the other implementation conditions are the same as in Example 1, to obtain the dimethylpyridinium copper complex (Cu(Ⅰ)-I) with a yield of 80.82%.
[0018] Example 4 The difference between this embodiment and Example 1 is that cuprous chloride is replaced with cuprous thiocyanate, while the other conditions are the same as in Example 1, resulting in a dimethylpyridinium copper complex (Cu(I)-SCN) with a yield of 70.59%.
[0019] Example 5 The difference between this embodiment and Example 1 is that cuprous chloride is replaced with copper chloride, while the other conditions are the same as in Example 1, resulting in a dimethylpyridinamine copper complex (Cu(II)-Cl2) with a yield of 76.73%.
[0020] The crystal structures of the products prepared in Examples 1-5 are as follows: Figures 1-5 As shown, the crystal data are presented in Tables 1-6. 1 H NMR spectrum as follows Figures 6-9 As shown, the IR spectrum is as follows Figures 10-14 As shown.
[0021] Table 1 Crystal data for Cu(Ⅰ)-Cl, Cu(Ⅰ)-Br, Cu(Ⅰ)-I, Cu(Ⅰ)-SCN and Cu(ⅠI)-Cl2
[0022] Table 2. Bond lengths and bond angles of Cu(Ⅰ)-Cl
[0023] Table 3 Bond lengths and bond angles of Cu(Ⅰ)-Br
[0024] Table 4. Bond lengths and bond angles of Cu(Ⅰ)-I
[0025] Table 5. Bond lengths and bond angles of Cu(Ⅰ)-SCN
[0026] Table 6 Bond lengths and bond angles of Cu(I)-Cl2
[0027] The following experiments were conducted using the dimethylpyridinamine copper complexes prepared in Examples 1-4 as catalyst samples.
[0028] Experimental Example 1: Photocatalytic Ammonia Oxidation 1. Weigh 7.5 mg of photosensitizer ([Ru(bpy)3]Cl2, purchased from Beijing Innocare Technology Co., Ltd.) and 80 mg of electron acceptor (7,7,8,8-tetracyanobenzoyldimethylethane, purchased from Beijing Innocare Technology Co., Ltd.) into a photocatalytic reaction instrument. Add 40 mL of chromatographic grade acetonitrile solution to completely dissolve them. Then, purge with ammonia gas for 2-3 hours. Next, add 100 μL and 2-5 mM of different dimethylpyridinium copper complex samples (Cu(I)-Cl, Cu(I)-Br, Cu(I)-I, Cu(I)-SCN). Take 100 μL of headspace from the reaction vessel for gas chromatography analysis to obtain blank chromatographic analysis results. Figures 15-18 The black curve in the image); then the light wavelength was fixed at 450 nm using a filter, and the light was irradiated for 1 hour. Then, 100 μL of headspace from the reaction vessel was taken for gas chromatography analysis to obtain the chromatographic analysis results of O2 and N2. Figures 15-18 (The blue curve in the image).
[0029] 2. Weigh 7.5 mg of photosensitizer ([Ru(bpy)3]Cl2) and 80 mg of electron acceptor (7,7,8,8-tetracyanobenzoyldimethylethane) into a photocatalytic reaction apparatus. Add 38 mL of chromatographically pure acetonitrile solution to completely dissolve them. Then, purge with ammonia gas for 2-3 hours, add 2 mL of 2.48 M NH3 acetonitrile solution, and then add 100 μL of different 2-5 mM dimethylpyridinium copper complex samples (Cu(I)-Cl, Cu(I)-Br, Cu(I)-I, Cu(I)-SCN). Take 100 μL of headspace from the reaction vessel for gas chromatography analysis to obtain the chromatographic analysis results. Then, fix the light wavelength at 450 nm with a filter and irradiate for 1 hour. Take another 100 μL of headspace from the reaction vessel for gas chromatography analysis to obtain the chromatographic analysis results of O2 and N2. Figures 15-18 (The red curve in the image).
[0030] like Figures 15-18 As shown, the first peak is the O2 content value, and the second peak is the N2 content value. Comparing the increase in the N2 signal peak before and after 1 hour of photocatalytic reaction, the increase in the N2 signal peak is significantly stronger than the increase in the O2 signal peak, indicating that N2 was produced during the photocatalytic ammonia oxidation reaction.
[0031] Using gas phase standard curve ( Figures 19-21 Quantitative calculations were performed to obtain the N2 turnover number (TON) after 1 h of photocatalytic reaction of different dimethylpyridinium copper complexes. The results are shown in Table 7.
[0032] Table 7. N2 turnovers for different dimethylpyridinium copper complex samples
[0033] As can be seen from Table 1, Cu(Ⅰ)-I has the highest N2 production turnover in acetonitrile solutions containing 2.48M and 0.12M NH3 due to the decrease in the first ionization energy among halide ions.
[0034] Experiment Example 2 To determine the amount of nitrogen-containing products in the catalytic solution during photocatalysis, the concentrations of N₂H₄ and NO₃⁻ in the reaction solution were analyzed using ultraviolet-visible methods. - NO2 - NH4 + The content of NH2OH was detected.
[0035] (1) Detection of hydrazine (N2H4) Preparation of colorimetric reagents: Take 5 mL of hydrochloric acid and dilute to 100 mL with deionized water to obtain colorimetric reagent A with a concentration of 0.6 M; weigh 1.82 g of 4-dimethylaminobenzaldehyde and dilute to 100 mL with ethanol to obtain colorimetric reagent B with a concentration of 18.2 g / L.
[0036] Calibration procedure: Transfer 0, 25, 50, 75, and 100 μL of 50 mg / L N₂H₄ solution to different colorimetric tubes, respectively. Then add 0.5 mL of colorimetric reagent A and 1.5 mL of colorimetric reagent B, and bring the volume to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 20 min. Quantitative analysis is performed using a UV-Vis spectrophotometer at λ=455 nm to obtain the standard curve of N₂H₄. Figure 30 ), used for subsequent quantitative calculations.
[0037] Quantitative method for N2H4 in solution after photocatalytic ammonia oxidation experiment: Take 1-2 mL of reaction solution into a 10 mL colorimetric tube, add 0.5 mL of colorimetric reagent A and 1.5 mL of colorimetric reagent B sequentially, and dilute to 10 mL. After thorough shaking, let the solution stand at room temperature for 20 min, and then use a UV-Vis spectrophotometer at a wavelength of λ=455 nm to quantitatively detect the residual hydrazine (N2H4) in the reaction system. The detection values of N2H4 after 1 h of irradiation with different dimethylpyridinium copper complexes are shown below. Figures 22-29 As shown in Table 8, the absorbance values of the reaction solution after photocatalytic ammonia oxidation using different catalysts were obtained. The N2H4 concentration and turnover number (TON) were calculated based on the N2H4 standard curve.
[0038] Table 8. N2H4 turnovers for different dimethylpyridinium copper complex samples
[0039] Table 8 shows that the coordinated halide ions and hexacyanide ions have a significant impact on the selectivity and activity of the copper dimethylpyridinamide complex. Cu(Ⅰ)-SCN exhibits the highest N2H4 turnover in acetonitrile solutions containing 2.48 M and 0.12 M ammonia. Furthermore, Cu(Ⅰ)-SCN achieves the highest N2H4 selectivity in acetonitrile solutions containing 2.48 M and 0.12 M ammonia, at 57.5% and 55.52%, respectively. The photocatalytic selectivity of the copper dimethylpyridinamide complex for N2H4 is independent of the ammonia concentration.
[0040] (2) Nitrate (NO3) - ) detection Preparation of colorimetric reagents: Take 4.165 mL of hydrochloric acid and dilute to 50 mL with deionized water to obtain colorimetric reagent A; weigh 0.432 g of aminosulfonic acid, dissolve it in hydrochloric acid, and then dilute to 50 mL with deionized water to obtain colorimetric reagent B.
[0041] Calibration procedure: Transfer 0, 250, 500, 750, and 1000 μL of 100 mg / L potassium nitrate solution to different colorimetric tubes. Add 100 μL of colorimetric reagent A and 10 μL of colorimetric reagent B to each tube, and then dilute to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 5 min. Quantitative analysis is performed using a UV-Vis spectrophotometer at λ=220 nm to obtain NO3. - Standard curve ( Figure 31 ), used for subsequent quantitative calculations.
[0042] NO3 in solution after photocatalytic ammonia oxidation experiment - Quantitative method: Take 100 μL of reaction solution, add 100 μL of colorimetric reagent A and 10 μL of colorimetric reagent B, and then dilute to 10 mL with deionized water. After developing the solution in the dark for 5 min, perform the detection.
[0043] (3) Nitrite (NO2) - ) detection Preparation of colorimetric reagent: Weigh 2g of p-aminobenzenesulfonamide, add 25mL of water to dissolve it, then add 5mL of phosphoric acid and 0.1g of 1-naphthylamine, and dilute to 10mL with deionized water to obtain the colorimetric reagent.
[0044] Calibration procedure: Transfer 0, 500, 1000, 1500, and 2000 μL of potassium nitrite solution with a concentration of 20 mg / L to different colorimetric tubes, add 100 μL of colorimetric reagent to each tube, shake the solution thoroughly, and incubate at room temperature in the dark for 10 min. Quantitative analysis is performed using a UV-Vis spectrophotometer at λ=540 nm to obtain NO2. - Standard curve ( Figure 32 ), used for subsequent quantitative calculations.
[0045] NO2 in solution after photocatalytic ammonia oxidation experiment - Quantitative method: Take 100 μL of reaction solution, add colorimetric reagent, and dilute to 10 mL with deionized water. Develop the solution in the dark for 10 min before detection.
[0046] (4) Ammonium ions (NH4) + ) detection Prepare colorimetric reagents: Prepare colorimetric reagent A (containing 1M sodium hydroxide, 5wt% salicylic acid and 5wt% sodium citrate), colorimetric reagent B (containing 0.05 M sodium hypochlorite solution) and colorimetric reagent C (1wt% sodium nitroprusside trihydrate).
[0047] Calibration procedure: Transfer 0, 250, 500, 750, and 1000 μL of ammonium chloride solution with a concentration of 100 mg / L to different colorimetric tubes. Add 2 mL of colorimetric reagent A, 1 mL of indicator B, and 0.2 mL of indicator C to each tube, and then dilute to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 1 hour. Quantitative analysis is performed using a UV-Vis spectrophotometer at λ=655 nm to obtain NH4+. + Standard curve ( Figure 33 ), used for subsequent quantitative calculations.
[0048] NH4 in solution after photocatalytic ammonia oxidation experiment + Quantitative method: Take 100 μL of reaction solution, add 2 mL of colorimetric reagent A, 1 mL of indicator B and 0.2 mL of indicator C, and then dilute to 10 mL with deionized water. After developing the solution in the dark for 1 hour, perform the detection.
[0049] (5) Detection of hydroxylamine (NH2OH) Preparation of colorimetric reagents: Prepare 1M sodium acetate and 1M acetic acid, and then mix them in a 1:1 volume ratio to obtain colorimetric reagent A; weigh 0.1931g of ferric ammonium sulfate and dilute to 100mL with deionized water to obtain colorimetric reagent B; weigh 0.1982g of non-phosphonoline and dilute to 100mL with ethanol to obtain colorimetric reagent C.
[0050] Calibration procedure: Transfer 0, 25, 50, 75, and 100 μL of 5 mmol / L hydroxylamine sulfate solution to different colorimetric tubes. Add colorimetric reagents A, B, and C respectively (400 μL of each reagent in each colorimetric tube), and then dilute to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 15 min. Quantitative analysis is performed using a UV-Vis spectrophotometer at λ=510 nm to obtain the standard curve for NH2OH. Figure 34 ), used for subsequent quantitative calculations.
[0051] Quantitative method for NH2OH in solution after photocatalytic ammonia oxidation experiment: Take 100 μL of reaction solution, add 400 μL of colorimetric reagent AC, and then dilute to 10 mL with deionized water. After developing the solution in the dark for 15 min, perform detection.
[0052] For ammonium ions (NH4) in the reaction system + ), nitrate (NO3) - ), nitrite (NO2) - Quantitative analysis was performed on the four nitrogen-containing compounds (NH4+, NH4+, and hydroxylamine (NH2OH)). No significant absorbance response was detected at their characteristic absorption wavelengths, indicating that NH4+ was not detected in the reaction system. + NO3 - NO2 -The presence of NH2OH indicates that no nitrogen-containing substances other than N2H4 are generated in the solution during this photocatalytic ammonia oxidation process.
Claims
1. A method for preparing a dimethylpyridinium copper complex, characterized in that, Includes the following steps: Raw material A and dimethylpyridinamide are mixed in an organic solvent at a molar ratio of 1-2:1-2 and reacted at room temperature for 2-6 hours. The mixture is then filtered, and the filtrate is dried to obtain a copper complex of dimethylpyridinamide. Raw material A is copper chloride, cuprous chloride, cuprous bromide, cuprous iodide, or cuprous thiocyanate.
2. The method for preparing the dimethylpyridinium copper complex according to claim 1, characterized in that, The organic solvent is acetonitrile, tetrahydrofuran, methanol, or dichloromethane.
3. The method for preparing the dimethylpyridinium copper complex according to claim 1, characterized in that, The drying temperature is room temperature, and the time is 22-26 hours.
4. A dimethylpyridinamine copper complex, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.
5. The dimethylpyridinamine copper complex according to claim 4, characterized in that, The structural formula of the dimethylpyridineamine copper complex is: , , , or .
6. The application of the dimethylpyridinium copper complex according to claim 4 or 5 in photocatalytic ammonia oxidation.