Preparation method of bifunctional photoelectrocatalytic material and application of bifunctional photoelectrocatalytic material in treatment of nitrate-containing wastewater and ammonia and gluconic acid production
The hydrothermal synthesis of Cu2O@CoMoO4/PVDF/Ti electrodes solves the problems of low charge separation efficiency and poor selectivity in photoelectrocatalysts, enabling efficient nitrate reduction and NH3 production under visible light and providing a green synthesis route.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2026-03-06
- Publication Date
- 2026-06-09
Smart Images
Figure CN122169142A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high value-added chemicals and catalyst production technology, specifically relating to a method for preparing a bifunctional photoelectrocatalytic material Cu2O@CoMoO4 / PVDF / Ti electrode and its application in the treatment of nitrate-containing wastewater for the synergistic production of ammonia and gluconic acid. Background Technology
[0002] Globally, nitrogen pollution has become a serious problem threatening aquatic environments and human health. Nitrate, one of the most common nitrogen pollutants, mainly originates from the excessive use of nitrogen fertilizers in agriculture, industrial wastewater discharge, and sewage leakage. Excessive nitrate entering water bodies can cause algal blooms, groundwater eutrophication, and even accumulate through the food chain, impacting human health and considered closely linked to diseases such as "blue baby syndrome" and cancer. Therefore, how to efficiently remove nitrates from the environment has become a crucial issue urgently needing to be addressed in the fields of environmental chemistry and energy conversion.
[0003] Traditional nitrate removal methods include biological denitrification, physical adsorption, and chemical reduction. While biological methods are widely used, their reaction processes depend on microbial activity and are limited by temperature, pH, and carbon source conditions, resulting in limited treatment efficiency. Physical methods such as ion exchange and reverse osmosis often suffer from high energy consumption or secondary pollution problems. Chemical reduction methods require expensive reducing agents and have low selectivity. These shortcomings have driven the exploration of green and controllable emerging strategies.
[0004] In recent years, photoelectrochemical nitrate reduction has attracted much attention due to its mild reaction conditions, simple operation, and ability to couple green light and electrical energy. In particular, the nitrate reduction pathway targeting ammonia (NH3) is considered a "win-win" approach for achieving environmental remediation and resource utilization. On the one hand, this process can effectively remove nitrates from water bodies, reducing environmental risks; on the other hand, ammonia, as an important nitrogen fertilizer and energy carrier, has enormous economic and strategic value. Currently, ammonia is mainly synthesized industrially through the Haber-Bosch process, which requires high temperature and high pressure conditions and consumes large amounts of fossil fuels, leading to huge carbon emissions. In contrast, electrochemical nitrate reduction can directly produce ammonia at ambient temperature and pressure, and is expected to become an important supplement or even a replacement for traditional processes. However, existing photoelectrochemical catalysts generally suffer from low charge separation efficiency, severe side reactions (HER), and poor selectivity.
[0005] Cobalt-based catalysts, such as CoMoO4, have attracted considerable research interest due to their unique electronic structure and efficient generation of active hydrogen (H*). Meanwhile, cuprous oxide (Cu2O) shows significant potential due to its strong affinity for nitrate ions and visible light responsiveness. The construction of heterojunctions can effectively promote the separation of photogenerated electron-hole pairs, thereby improving light utilization efficiency and reaction kinetics. This invention synthesizes a photothermal Cu2O@CoMoO4 heterojunction catalyst with a ball-and-bar morphology using a hydrothermal method. Summary of the Invention
[0006] One objective of this invention is to provide a Cu2O@CoMoO4 / PVDF / Ti electrode with visible light response, capable of effectively separating photogenerated electrons and having a ball-and-bar morphology, and its preparation method.
[0007] The second objective of this invention is to provide a method for photoelectrochemical treatment of nitrate-containing wastewater with the synergistic production of ammonia and gluconic acid using a ball-and-stick shaped Cu2O@CoMoO4 / PVDF / Ti electrode.
[0008] The technical solution adopted in this invention is:
[0009] A bifunctional photoelectrocatalytic material is proposed. First, spherical Cu2O particles are obtained by reducing copper salt with ascorbic acid under alkaline conditions using a chemical precipitation method. Second, highly crystalline CoMoO4 nanoparticles are synthesized by hydrothermal bonding followed by calcination. Then, the prepared Cu2O and CoMoO4 are dispersed in water and ultrasonically self-assembled by electrostatic attraction to form a Cu2O@CoMoO4 heterostructure composite material. Finally, Cu2O@CoMoO4 is uniformly coated onto a Ti mesh using PVDF to obtain a Cu2O@CoMoO4 / PVDF / Ti electrode.
[0010] The preparation method of the above-mentioned bifunctional photoelectrocatalytic material includes the following steps:
[0011] 1) Preparation of Cu2O: NaOH solution was added dropwise to CuCl2 solution and stirred continuously for 10 minutes at room temperature; then, ascorbic acid solution was added and stirring was continued for 1 hour; after the reaction was completed, the product was collected by centrifugation, washed three times with deionized water and anhydrous ethanol, and dried at 60°C for 6 hours to obtain spherical Cu2O.
[0012] 2) Preparation of CoMoO4: Co(NO3)2·6H2O and Na2MoO4·2H2O were dispersed in deionized water and stirred at room temperature for 20 minutes. The mixture was then transferred to a Teflon-lined stainless steel autoclave and heated to obtain a low-crystallinity CoMoO4 precursor. After naturally cooling to room temperature, the precursor was centrifuged and washed three times with deionized water and ethanol to remove unreacted impurities. It was then dried overnight in a vacuum oven at 60°C. The CoMoO4 precursor was calcined and the sample was collected after naturally cooling to room temperature to finally obtain a high-crystallinity CoMoO4.
[0013] 3) Preparation of Cu2O@CoMoO4: The Cu2O obtained in step 1) and the CoMoO4 obtained in step 2) are mixed in deionized water and ultrasonically treated to obtain Cu2O@CoMoO4;
[0014] 4) Preparation of Cu2O@CoMoO4 / PVDF / Ti: The Cu2O@CoMoO4 obtained in step 3) was mixed with 8wt% PVDF solution and ultrasonically treated for 2 h; then the resulting slurry was uniformly coated on Ti mesh and dried in air to obtain Cu2O@CoMoO4 / PVDF / Ti electrode.
[0015] In the preparation method described above, in step 1), the concentration of the NaOH solution is 2 M and the volume is 100 mL; the concentration of the CuCl2 solution is 0.1 M and the volume is 50 mL; the concentration of the ascorbic acid solution is 0.1 M and the volume is 50 mL.
[0016] In the preparation method described above, in step 2), the molar ratio of Co(NO3)2·6H2O and Na2MoO4·2H2O is 1:1.
[0017] In the preparation method described above, step 2) involves heating at 160°C for 6 hours.
[0018] In the preparation method described above, step 2) involves calcination conditions of: heating at 5°C / min in air and maintaining at 350°C for 2 hours.
[0019] In the preparation method described above, in step 3), the mass ratio of Cu2O to CoMoO4 is 1:3.
[0020] In the preparation method described above, in step 4), the solvent of the 8 wt% PVDF solution is DMF.
[0021] The above-mentioned bifunctional photoelectrocatalytic material is used in the treatment of nitrate-containing wastewater to synergistically produce ammonia and gluconic acid.
[0022] Furthermore, the above application method is as follows: Cu2O@CoMoO4 / PVDF / Ti is used as the cathode working electrode, Cu2O@CoMoO4 / PVDF / Ti is used as the anode working electrode, and a silver / silver chloride electrode is used as the reference electrode. These are placed in an H-type reactor to form a three-electrode system. The cathode electrolyte is 0.5M sodium sulfate and 0.05M sodium nitrate, and the anode electrolyte is 0.5M sodium sulfate and 25-300mM glucose solution. Before the reaction, argon gas is introduced into the cathode electrolyte for 30 minutes. Under the conditions of -1.4 V vs. RHE bias voltage and ambient temperature of 25°C, a 300 W xenon lamp with λ≥420nm is used to simulate sunlight irradiation to catalyze the synthesis of NH3 and gluconic acid.
[0023] The beneficial effects of this invention are:
[0024] 1. This invention synthesizes Cu2O@CoMoO4 / PVDF / Ti electrodes via hydrothermal method, calcination, and electrostatic attraction, further improving photoresponse, suppressing electron-hole recombination, increasing electron-hole utilization, enhancing nitrate adsorption capacity, and improving local H+ adsorption. * Concentration increases photocatalytic activity.
[0025] 2. Under visible light irradiation and a specific additional bias voltage, a flow cell was used to achieve 14 mmol h⁻¹. -1 cm -2 The ultra-high NH3 yield provides a green synthetic route and sustainable technology for NH3 production.
[0026] 3. This invention is characterized by its simplicity, high efficiency, and low cost. The prepared Cu2O@CoMoO4 / PVDF / Ti electrode exhibits good conductivity, excellent nitrate adsorption, and high catalytic activity. It also demonstrates good visible light absorption and stability, high photogenerated electron-hole pair separation efficiency, fast interfacial charge transport efficiency, and high NH3 production yield. Furthermore, it achieves high conversion rates in the synergistic production of gluconic acid. It can be applied to the field of photoelectrocatalytic NH3 production. Attached Figure Description
[0027] Figure 1 These are transmission electron micrographs (TEM) of CoMoO4 (a), Cu2O (b), and Cu2O@CoMoO4 (c).
[0028] Figure 2 The images show the XRD (a) and XPS (b) plots of Cu2O, CoMoO4, and Cu2O@CoMoO4.
[0029] Figure 3 These are the EIS and transient photocurrent plots of Cu2O, CoMoO4, and Cu2O@CoMoO4.
[0030] Figure 4 The graphs (a) and (b) show the OCPT changes of Cu2O, CoMoO4, and Cu2O@CoMoO4.
[0031] Figure 5 This is the FT-IR image of Cu2O@CoMoO4.
[0032] Figure 6 This is a comparison chart of NH3 production and FE at different concentrations in the H-type reactor and the flow cell.
[0033] Figure 7 The graph shows the yield of NH3 and gluconic acid at different concentrations.
[0034] Figure 8 This is a flowchart of the synthesis process of Cu2O@CoMoO4. Detailed Implementation
[0035] Example 1: Fabrication of a photothermal Cu2O@CoMoO4 / PVDF / Ti electrode with a ball-and-bar morphology
[0036] (I) Preparation of Cu2O
[0037] 100 mL of 2 M NaOH solution was added dropwise to 50 mL of 0.1 M CuCl2 solution, and the mixture was stirred continuously at room temperature for 10 minutes. Then, 50 mL of 0.1 M ascorbic acid solution was added, and stirring was continued for 1 hour. After the reaction was completed, the product was collected by centrifugation, washed three times with deionized water and anhydrous ethanol, and dried at 60 °C for 6 hours to obtain spherical Cu2O.
[0038] (II) Preparation of CoMoO4
[0039] 4 mmol (1.1641 g) of Co(NO3)2·6H2O and 4 mmol (0.9678 g) of Na2MoO4·2H2O were dispersed in 60 mL of deionized water. After stirring at room temperature for 20 minutes, the mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave and heated in an oven at 160°C for 6 hours to obtain a low-crystallinity CoMoO4 precursor. After naturally cooling to room temperature, the precursor was centrifuged and washed three times with deionized water and ethanol to remove unreacted impurities. The CoMoO4 precursor was then dried overnight in a vacuum oven at 60°C. Finally, the CoMoO4 precursor was heated in air at 350°C for 2 hours at a heating rate of 5°C / min, and the sample was collected after naturally cooling to room temperature. High-crystallinity CoMoO4 was thus obtained.
[0040] (III) Preparation of Cu2O@CoMoO4
[0041] 0.01 g Cu2O and 0.03 g CoMoO4 were mixed in 30 mL of deionized water (DI water) and sonicated for 2 h to obtain Cu2O@CoMoO4.
[0042] (iv) Preparation of 8 wt% PVDF
[0043] Dissolve 0.02 g of PVDF in 0.25 mL of LMF solution to obtain 8 wt% PVDF.
[0044] (V) Preparation of Cu2O@CoMoO4 / PVDF / Ti
[0045] 20 mg of the catalyst material Cu2O@CoMoO4 was mixed with 20 μL of 8 wt% PVDF solution. The resulting slurry was then uniformly coated onto a titanium mesh (2 cm × 2 cm) and dried in air. Thus, a Cu2O@CoMoO4 / PVDF / Ti electrode was prepared for further use.
[0046] (v) Testing
[0047] 1. For example Figure 1 As shown, (a), (b), and (c) are TEM images of CoMoO4, Cu2O, and Cu2O@CoMoO4, respectively. CoMoO4 has a rod-like structure with a length of up to 5 μm and a diameter of about 1 μm, while the synthesized Cu2O is spherical with a uniform diameter of about 1 μm. After ultrasonic reconstruction for 2 h, Cu2O studs are visible on the CoMoO4.
[0048] 2. For example Figure 2 As shown, (a) and (b) are the XRD and XPS spectra, respectively. XRD confirms the successful synthesis of the material. XPS analysis of the O-1s spectrum shows that, compared with Cu2O and CoMoO4, the OV peak height in the coupled Cu2O@CoMoO4 is significantly enhanced, indicating a significant increase in OV concentration, which is beneficial to improving the photocatalytic ammonia production performance.
[0049] 3. For example Figure 3 As shown, (a) and (b) are EIS and transient photocurrent plots, respectively. In Figure (a), Cu2O@CoMoO4 exhibits a smaller charge transfer resistance. In Figure (b), Cu2O@CoMoO4 exhibits a stronger transient photocurrent. This indicates that ionic liquids can enhance the conductivity of Cu2O@CoMoO4 and suppress carrier recombination.
[0050] 4. For example Figure 4As shown, (a) and (b) are the OCPT change graph and CDL graph, respectively. Cu2O@CoMoO4 exhibits a larger OCPT change and a smaller reaction order, indicating that ionic liquids can significantly enhance the adsorption capacity for nitrates.
[0051] 5. Figure 5 This is an FT-IR plot. Cu2O@CoMoO4 shows H * The characteristic peaks indicate that Cu2O@CoMoO4 can promote H2O. * produce.
[0052] Example 2: Photoelectrocatalytic production of NH3
[0053] (a) The method is as follows:
[0054] 1) A three-electrode system is formed by using Cu2O@CoMoO4 / PVDF / Ti as the working electrode, a platinum sheet as the counter electrode, and a silver / silver chloride electrode as the reference electrode in a flow reactor.
[0055] 2) Cathode electrolyte: Prepare nitrate solutions with gradient concentrations of 50, 100, 200, 500, 800 and 1000 mM.
[0056] 3) Before the reaction, argon gas was introduced into the cathode electrolyte for 30 minutes. Under the conditions of -1.4 V vs. RHE bias and ambient temperature of 25°C, a 300 W xenon lamp (λ≥420nm) was used to simulate sunlight irradiation for the photoelectrocatalysis experiment. After 60 minutes of reaction, 0.5 mL of cathode electrolyte was taken, diluted with water to 10 mL, and 0.2 mL of 10M sodium hydroxide solution was added. The NH3 concentration was then detected using a gas-sensitive electrode.
[0057] (II) Comparison of the effects of different nitrate concentrations on NH3 generation in H-type cells and flow cells
[0058] Photocatalytic experiments were conducted in electrolytes with nitrate concentrations of 50, 100, 200, 500, 800, and 1000 mM, and the results are as follows: Figure 6 As shown.
[0059] As nitrate concentration gradually increases, NH3 production gradually increases, reaching a maximum at 800 mM, achieving 14 mmol / L. -1 cm -2 The NH3 yield is extremely high. In particular, under the condition of 1000 mM, the NH3 yield of the flow cell is about 32 times that of the H-type cell.
[0060] Example 3: Photoelectrocatalytic production of NH3 and co-catalytic oxidation of glucose to gluconic acid
[0061] (a) The method is as follows:
[0062] 1) Using Cu2O@CoMoO4 / PVDF / Ti as the cathode working electrode, Cu2O@CoMoO4 / PVDF / Ti as the anode working electrode, and silver / silver chloride electrode as the reference electrode, a three-electrode system is formed in an H-type reactor.
[0063] 2) Prepare glucose solutions with gradient concentrations of 25, 50, 100, 200 and 300 mM.
[0064] 3) The cathode electrolyte is 0.5M sodium sulfate and 0.05M sodium nitrate, and the anolyte is 0.5M sodium sulfate and a gradient concentration glucose solution.
[0065] 4) Before the reaction, argon gas was introduced into the cathode electrolyte for 30 minutes. Under the conditions of -1.4 V vs. RHE bias and ambient temperature of 25°C, a 300 W xenon lamp (λ≥420nm) was used to simulate sunlight irradiation for the photoelectrocatalysis experiment. After 60 minutes of reaction, 0.5 mL of cathode electrolyte was taken, diluted with water to 10 mL, and 0.2 mL of 10M sodium hydroxide solution was added. The NH3 concentration was then detected using a gas-sensitive electrode.
[0066] (II) Effect of different glucose solution concentrations on gluconic acid formation
[0067] Photocatalytic experiments were conducted in electrolytes with glucose concentrations of 25, 50, 100, 200, and 300 mM, and the results are as follows: Figure 7 As shown.
[0068] As glucose concentration gradually increases, gluconic acid production gradually increases, reaching a peak of 145 mmol / h at 100 mM. -1 cm -2 The extremely high gluconic acid yield and 7.87 mmol h -1 cm -2 NH3.
Claims
1. A bifunctional photoelectrocatalytic material, characterized in that, First, spherical Cu2O particles were obtained by reducing copper salt with ascorbic acid under alkaline conditions using a chemical precipitation method. Second, highly crystalline CoMoO4 nanoparticles were synthesized by hydrothermal bonding followed by calcination. Then, the prepared Cu2O and CoMoO4 were dispersed in water and ultrasonically self-assembled by electrostatic attraction to form a Cu2O@CoMoO4 heterostructure composite material. Finally, Cu2O@CoMoO4 was uniformly coated onto a Ti mesh using PVDF to obtain a Cu2O@CoMoO4 / PVDF / Ti electrode.
2. The method for preparing a bifunctional photoelectrocatalytic material according to claim 1, characterized in that, Includes the following steps: 1) Preparation of Cu2O: NaOH solution was added dropwise to CuCl2 solution and stirred continuously for 10 minutes at room temperature; then, ascorbic acid solution was added and stirring was continued for 1 hour; after the reaction was completed, the product was collected by centrifugation, washed three times with deionized water and anhydrous ethanol, and dried at 60°C for 6 hours to obtain spherical Cu2O. 2) Preparation of CoMoO4: Co(NO3)2·6H2O and Na2MoO4·2H2O were dispersed in deionized water and stirred at room temperature for 20 minutes. The mixture was then transferred to a Teflon-lined stainless steel autoclave and heated to obtain a low-crystallinity CoMoO4 precursor. After naturally cooling to room temperature, the precursor was centrifuged and washed three times with deionized water and ethanol to remove unreacted impurities. It was then dried overnight in a vacuum oven at 60°C. The CoMoO4 precursor was calcined and the sample was collected after naturally cooling to room temperature to finally obtain a high-crystallinity CoMoO4. 3) Preparation of Cu2O@CoMoO4: The Cu2O obtained in step 1) and the CoMoO4 obtained in step 2) are mixed in deionized water and ultrasonically treated to obtain Cu2O@CoMoO4; 4) Preparation of Cu2O@CoMoO4 / PVDF / Ti: The Cu2O@CoMoO4 obtained in step 3) was mixed with 8wt% PVDF solution and ultrasonically treated for 2 h; then the resulting slurry was uniformly coated on Ti mesh and dried in air to obtain Cu2O@CoMoO4 / PVDF / Ti electrode.
3. The preparation method according to claim 2, characterized in that, In step 1), the concentration of the NaOH solution is 2M and the volume is 100 mL; the concentration of the CuCl2 solution is 0.1 M and the volume is 50 mL; the concentration of the ascorbic acid solution is 0.1 M and the volume is 50 mL.
4. The preparation method according to claim 2, characterized in that, In step 2), the molar ratio of Co(NO3)2·6H2O and Na2MoO4·2H2O is 1:
1.
5. The preparation method according to claim 2, characterized in that, In step 2), the heating reaction conditions are: heating at 160°C for 6 hours.
6. The preparation method according to claim 2, characterized in that, In step 2), the calcination conditions are: in air, the heating rate is 5℃ / min, and the temperature is maintained at 350℃ for 2 hours.
7. The preparation method according to claim 2, characterized in that, In step 3), the mass ratio of Cu2O to CoMoO4 is 1:
3.
8. The preparation method according to claim 2, characterized in that, In step 4), the solvent of the 8 wt% PVDF solution is DMF.
9. The application of the bifunctional photoelectrocatalytic material according to claim 1 in the treatment of nitrate-containing wastewater for synergistic ammonia and gluconic acid production.
10. The application according to claim 9, characterized in that, The application method is as follows: Cu2O@CoMoO4 / PVDF / Ti is used as the cathode working electrode, Cu2O@CoMoO4 / PVDF / Ti is used as the anode working electrode, and a silver / silver chloride electrode is used as the reference electrode. The electrodes are placed in an H-type reactor to form a three-electrode system. The cathode electrolyte is 0.5M sodium sulfate and 0.05M sodium nitrate, and the anode electrolyte is 0.5M sodium sulfate and 25-300mM glucose solution. Before the reaction, argon gas is introduced into the cathode electrolyte for 30 minutes. Under the conditions of -1.4 V vs. RHE bias voltage and ambient temperature of 25°C, a 300 W xenon lamp with λ≥420nm is used to simulate sunlight irradiation to catalyze the synthesis of NH3 and gluconic acid.