A copper-bismuth catalyst based on phase engineering regulation and application thereof in seawater carbon dioxide conversion
By using phase engineering-controlled Cu-Bi catalysts, the problems of insufficient efficiency and stability of copper-based catalysts in seawater were solved, achieving efficient conversion of CO2 into formic acid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN NORMAL UNIV
- Filing Date
- 2026-03-24
- Publication Date
- 2026-06-09
AI Technical Summary
Copper-based catalysts exhibit low catalytic efficiency, poor selectivity, and poor stability in seawater electrolyte systems, especially in complex seawater environments.
A phase engineering control method was used to prepare Bi2S3 catalyst via hydrothermal method, and then Cu2O-Bi2S3@Bi catalyst was synthesized by sodium borohydride reduction method. By controlling the molar ratio of Cu to Bi and the amount of NaBH4 added, a heterogeneous copper nanostructure was formed, which improved the catalytic performance.
The system achieved highly efficient catalytic conversion of CO2 to formic acid in simulated seawater, with a selectivity greater than 85%, a current density greater than 40 mA cm-2, and stability close to that of potassium bicarbonate solution, with a current decay of less than 20% after 16 hours of electrolysis.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of comprehensive utilization of carbon dioxide, specifically relating to a copper-bismuth catalyst based on phase engineering regulation and its application in seawater carbon dioxide conversion. Background Technology
[0002] Excessive carbon dioxide (CO2) emissions have become a core global climate challenge, and promoting its efficient conversion is a crucial task for the scientific community. Converting CO2 into high-value-added industrial raw materials has become an important research direction for achieving carbon reduction and resource recycling. The ocean is the Earth's largest CO2 reservoir; directly utilizing CO2 from seawater for conversion not only achieves efficient resource utilization but also significantly reduces conversion costs by leveraging seawater as an inexpensive reaction medium.
[0003] Currently, CO2 conversion is mainly achieved through methods such as chemical reduction, photocatalysis, and electrochemistry. Among these, electrochemical reduction (CO2RR) has become a research hotspot due to its mild operation and controllable products. CO2RR can be driven by renewable energy sources such as solar and wind power, which are abundant in nearshore areas, providing possibilities for green conversion.
[0004] Electrocatalysts are the core of CO2RR, lowering the activation energy of the reaction. While transition metal catalysts are simple in composition and highly controllable, they generally suffer from low efficiency and high overpotentials, and face competition from poor selectivity and the hydrogen evolution reaction (HER). Copper-based catalysts have become a research focus due to their ability to catalyze CO2 reduction at relatively low potentials. However, copper catalysts exhibit poor product selectivity and insufficient stability, particularly in complex seawater systems, and rising copper prices further limit their practical application.
[0005] Phase engineering, an emerging nanotechnology, has attracted much attention in recent years for optimizing catalytic performance by controlling the crystal phase structure of materials. Compared with precious metals, copper has a cost advantage in phase engineering. Heterogeneous copper nanomaterials obtained through phase engineering exhibit good performance in CO2RR due to their unique crystal phase structure. However, heterogeneous structures have high surface energy and poor stability, especially in seawater environments. Therefore, it is necessary to design binary heterogeneous copper nanostructures and combine them with active components to improve their electrocatalytic stability in complex systems. Summary of the Invention
[0006] The purpose of this invention is to solve the problems of low catalytic efficiency, poor selectivity and stability of Cu-based catalysts in seawater electrolyte systems, and to provide a copper-bismuth (Cu-Bi) catalyst based on phase engineering regulation and its application in seawater carbon dioxide conversion.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A method for preparing a copper-bismuth catalyst based on phase engineering regulation includes the following steps:
[0009] 1) Preparation of Bi2S3 catalyst by hydrothermal method
[0010] Add Bi(NO3)3·5H2O, C2H8N2 and C6H8O7·H2O to water and stir for 30-40 min to obtain solution A; dissolve C3H7NO2S in water and stir for 30-40 min to obtain solution B;
[0011] Mix solution A and solution B and stir for 10-20 min, then transfer to a stainless steel autoclave. Heat to 170-190℃ and react for 18-20 h. After the reaction is complete, perform solid-liquid separation on the product. Wash and dry the obtained solid to obtain Bi2S3.
[0012] 2) Synthesis of Cu2O-Bi2S3@Bi catalyst using sodium borohydride reduction method
[0013] A mixture of Bi₂S₃ and Cu(NO₃)₂·3H₂O was added to water and stirred for 30-40 min. The molar ratio of Bi₂S₃ to Cu(NO₃)₂·3H₂O in the mixture was 0.10: 0.05-0.30. Then, 0.01-0.08 g / mL of NaBH₄ solution was added dropwise. The reduction reaction was carried out for 4.5-5.5 h. After the reaction was completed, the product was separated into solid and liquid phases. The obtained solid was washed and dried to obtain the Cu₂O-Bi₂S₃@Bi catalyst.
[0014] Further, in step 1), when preparing solution A, the ratio of water, Bi(NO3)3·5H2O, C2H8N2 and C6H8O7·H2O is 10 mL:0.48-0.52 g:0.75-0.85 mL:0.11-0.13 g.
[0015] Further, in step 1), when preparing solution B, the ratio of C3H7NO2S to water is 0.40-0.45 g: 5 mL.
[0016] Further, in step 1), the heating rate is 4.5-5.5℃ / min; the washing involves washing the solid obtained after solid-liquid separation with H2O and C2H5OH sequentially; the drying temperature is 55-65℃ and the time is 10-14 h.
[0017] Further, in step 2), the ratio of the total mass of the Bi2S3 and Cu(NO3)2·3H2O mixture, the amount of water, and the amount of NaBH4 solution is 0.063-0.123g:100mL:10mL.
[0018] Further, in step 2), the washing involves washing the solid obtained after solid-liquid separation with water and anhydrous ethanol in sequence, and the drying temperature is 55-65℃ for 12-14 h.
[0019] Furthermore, the Cu2O-Bi2S3@Bi catalyst can be used for the conversion of carbon dioxide in seawater.
[0020] This invention employs the above technical solution, first preparing a Bi₂S₃ catalyst via a hydrothermal method, and then synthesizing a Cu₂O-Bi₂S₃@Bi catalyst via sodium borohydride reduction. This invention utilizes Bi as the second component and employs phase engineering strategies to control the composition, structural morphology, and other properties of the Cu-Bi catalyst, enabling highly efficient electrocatalytic conversion of carbon dioxide in seawater. During catalyst preparation, the molar ratio of Cu to Bi and the amount of NaBH₄ added are two key regulating factors. From the perspective of two-phase composition and morphology, insufficient Cu content results in fewer Cu groups or potential sites, leading to slower reaction efficiency. Excessive Cu content causes nanoparticles (granular) to easily aggregate, reducing the active surface area. Simultaneously, excessive Cu₂O in the rod-shaped structure may cover Bi active sites (due to Bi's good selectivity for HCOOH), shifting product selectivity from HCOOH to other products and intensifying HER competition. Therefore, excessive Cu content affects the catalyst's morphology and phase composition sites, weakening its performance. Furthermore, the amount of NaBH4 added has a significant regulatory effect on the composition, structure, and morphology of the catalyst. When the amount of NaBH4 reducing agent in the catalyst is small, the catalyst morphology exists in the form of chocolate bars. As the amount of NaBH4 reducing agent gradually increases, Cu2O is gradually precipitated due to the action of the reducing agent, and sugar-like nanoparticles (Cu2O) appear around the chocolate bars, that is, a chocolate bar-like morphology with sugar granules appears. Moreover, as the amount of reducing agent increases, Cu2O gradually increases until it agglomerates, thereby affecting the catalytic performance.
[0021] The present invention has the following beneficial effects:
[0022] 1. The Cu2O-Bi2S3@Bi catalyst of this invention exhibits catalytic efficiency in simulated seawater that is close to (more than 90% of) that in potassium bicarbonate solution, and the current density in the H-type electrolytic cell is greater than 40 mA cm⁻¹. -2 The current density in the flow cell electrolyzer is greater than 300 mA cm⁻¹ -2 .
[0023] 2. The Cu2O-Bi2S3@Bi catalyst of the present invention exhibits a selectivity of greater than 85% for the electrocatalytic conversion of CO2 into formic acid in simulated seawater electrolyte.
[0024] 3. The Cu2O-Bi2S3@Bi catalyst of the present invention exhibits catalytic stability in simulated seawater that is close to its stability in potassium bicarbonate solution. After 16 hours of electrolysis, the current decay is less than 20%. Attached Figure Description
[0025] Figure 1 The image shows the microstructure of the Cu2O-Bi2S3@Bi catalyst prepared in Example 1.
[0026] Figure 2 The image shows the microstructure of the Cu2O-Bi2S3@Bi catalyst prepared in Example 2.
[0027] Figure 3 The image shows the microstructure of the Cu2O-Bi2S3@Bi catalyst prepared in Example 3. Detailed Implementation
[0028] Example 1
[0029] A method for preparing a copper-bismuth catalyst based on phase engineering regulation includes the following steps:
[0030] 1) Preparation of Bi2S3 catalyst by hydrothermal method
[0031] Add 0.50 g Bi(NO3)3·5H2O, 0.80 mL C2H8N2, and 0.12 g C6H8O7·H2O to 10 mL of deionized water and stir for 30 min to obtain solution A; dissolve 0.424 g C3H7NO2S in 5 mL of deionized water and stir for 30 min to obtain solution B; mix solution A and solution B and stir for 10 min, then transfer to a stainless steel autoclave and heat to 180℃ at a rate of 5℃ / min. React for 18 h. After the reaction, perform solid-liquid separation on the product. Wash the obtained solid with H2O and C2H5OH in sequence. Dry the washed solid in a vacuum drying oven at 60℃ for 12 h to obtain Bi2S3.
[0032] 2) Synthesis of Cu2O-Bi2S3@Bi catalyst using sodium borohydride reduction method
[0033] A mixture of 0.075 g Bi₂S₃ and Cu(NO₃)₂·3H₂O was added to 100 mL of deionized water and stirred for 30 min. The molar ratio of Bi₂S₃ to Cu(NO₃)₂·3H₂O in the mixture was 0.10:0.10. Then, 10 mL of 0.02 g / mL NaBH₄ solution was added dropwise, and the reduction reaction was carried out for 5 h. After the reaction was completed, the product was separated into solid and liquid phases. The obtained solid was washed successively with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain the Cu₂O-Bi₂S₃@Bi catalyst. The morphology is detailed in [link to morphology chart]. Figure 1 .
[0034] Catalytic performance tests were conducted on a Chenhua CHI650 electrochemical workstation. The electrocatalytic carbon dioxide reduction reaction (CO2RR) experiment was performed in an H-type electrolytic cell or flow cell separated by an ion-exchange membrane. The electrolyte was either 0.5 M potassium bicarbonate solution or simulated seawater (0.6 M sodium chloride solution). Before the experiment, high-purity CO2 (99.99%) was continuously passed through the electrolyte for at least 30 minutes to obtain a saturated CO2 electrolyte. A three-electrode system was used: a platinum column as the auxiliary electrode, silver chloride (Ag / AgCl) as the reference electrode, and modified carbon paper as the working electrode. The entire experiment was conducted at ambient pressure and room temperature, while strictly ensuring the sealing of the electrolytic cell. During testing, a constant 20 mL / min flow rate was used. -1 High-purity CO2 is delivered to the cathode chamber at a controlled flow rate, while a stable magnetic stirring speed is maintained to ensure stable reaction conditions within the system. Performance testing revealed that Cu2O-Bi2S3@Bi exhibits high catalytic selectivity in simulated seawater, with a Faradaic efficiency exceeding 88% for the catalytic production of formic acid, and high current density, with a maximum current density exceeding 40 mA cm⁻¹. -2 The current density in the flow cell electrolyzer is greater than 300 mA cm⁻¹ -2 It exhibits good catalytic stability; after 16 hours of electrolysis, the FEHCOOH content remains stable at over 80%, and the total current density remains relatively stable with a current decay of less than 20%.
[0035] Example 2
[0036] A method for preparing a copper-bismuth catalyst based on phase engineering regulation includes the following steps:
[0037] 1) Preparation of Bi2S3 catalyst by hydrothermal method
[0038] Add 0.50 g Bi(NO3)3·5H2O, 0.80 mL C2H8N2, and 0.12 g C6H8O7·H2O to 10 mL of deionized water and stir for 30 min to obtain solution A; dissolve 0.424 g C3H7NO2S in 5 mL of deionized water and stir for 30 min to obtain solution B; mix solution A and solution B and stir for 10 min, then transfer to a stainless steel autoclave and heat to 180℃ at a rate of 5℃ / min. React for 18 h. After the reaction, separate the solid and liquid products. Wash the obtained solid with H2O and C2H5OH in sequence. Dry the washed solid in a vacuum drying oven at 60℃ for 12 h to obtain Bi2S3.
[0039] 2) Synthesis of Cu2O-Bi2S3@Bi catalyst using sodium borohydride reduction method
[0040] A mixture of 0.099 g Bi₂S₃ and Cu(NO₃)₂·3H₂O was added to 100 mL of deionized water and stirred for 30 min. The molar ratio of Bi₂S₃ to Cu(NO₃)₂·3H₂O was 0.10:0.20. Then, 10 mL of 0.02 g / mL NaBH₄ solution was added dropwise, and the reduction reaction was carried out for 5 h. After the reaction was completed, the product was separated into solid and liquid phases. The obtained solid was washed successively with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain the Cu₂O-Bi₂S₃@Bi catalyst. The morphology is detailed in [link to morphology chart]. Figure 2 .
[0041] The catalytic performance testing method was the same as in Example 1. Performance testing revealed that Cu2O-Bi2S3@Bi exhibited high catalytic selectivity in simulated seawater, with a Faradaic efficiency exceeding 80% for the catalytic production of formic acid, and high current density, with a maximum current density exceeding 35 mA cm⁻¹. -2 It exhibits good catalytic stability. After 16 hours of electrolysis, the FEHCOOH content remains stable at over 70%, and the total current density remains relatively stable with a current value decay of less than 25%.
[0042] Example 3
[0043] A method for preparing a copper-bismuth catalyst based on phase engineering regulation includes the following steps:
[0044] 1) Preparation of Bi2S3 catalyst by hydrothermal method
[0045] Add 0.50 g Bi(NO3)3·5H2O, 0.80 mL C2H8N2, and 0.12 g C6H8O7·H2O to 10 mL of deionized water and stir for 30 min to obtain solution A; dissolve 0.424 g C3H7NO2S in 5 mL of deionized water and stir for 30 min to obtain solution B; mix solution A and solution B and stir for 10 min, then transfer to a stainless steel autoclave and heat to 180℃ at a rate of 5℃ / min. React for 18 h. After the reaction, separate the solid and liquid products. Wash the obtained solid with H2O and C2H5OH in sequence. Dry the washed solid in a vacuum drying oven at 60℃ for 12 h to obtain Bi2S3.
[0046] 2) Synthesis of Cu2O-Bi2S3@Bi catalyst using sodium borohydride reduction method
[0047] A mixture of 0.099 g Bi₂S₃ and Cu(NO₃)₂·3H₂O was added to 100 mL of deionized water and stirred for 30 min. The molar ratio of Bi₂S₃ to Cu(NO₃)₂·3H₂O was 0.10:0.20. Then, 10 mL of 0.01 g / mL NaBH₄ solution was added dropwise, and the reduction reaction was carried out for 5 h. After the reaction was completed, the product was separated into solid and liquid phases. The obtained solid was washed successively with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain the Cu₂O-Bi₂S₃@Bi catalyst. The morphology is detailed in [link to morphology chart]. Figure 3 .
[0048] The catalytic performance testing method was the same as in Example 1. Performance testing revealed that Cu2O-Bi2S3@Bi exhibited high catalytic selectivity in simulated seawater, with a Faradaic efficiency exceeding 80% for the catalytic production of formic acid, and high current density, with a maximum current density exceeding 35 mA cm⁻¹. -2 It exhibits good catalytic stability. After 16 hours of electrolysis, the FEHCOOH content remains stable at over 75%, and the total current density remains relatively stable with a current value decay of less than 25%.
[0049] Compare with Example 1
[0050] The preparation method was the same as in Example 1, except that Cu(NO3)2·3H2O was not added, and other conditions remained unchanged, to obtain the control catalyst Bi2S3@Bi. The catalytic efficiency of the obtained catalyst (the highest current density for formic acid production was less than 15 mA cm⁻¹) was [not specified in the original text]. -2 The selectivity is significantly reduced (the efficiency of producing formic acid faradaic acid is less than 80%).
[0051] Compare with Example 2
[0052] The preparation method was the same as in Example 1, but without the addition of Bi₂S₃. Specifically, 0.024 g of Cu(NO₃)₂·3H₂O was added to 100 mL of deionized water and stirred for 30 min. Then, 10 mL of 0.02 g / mL NaBH₄ solution was added dropwise, and the reduction reaction was carried out for 5 h. After the reaction, the product was separated into solid and liquid phases. The obtained solid was washed successively with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain the Cu₂O catalyst. The obtained catalyst exhibited poor catalytic selectivity (formic acid production Faradaic efficiency less than 45%).
Claims
1. A method for preparing a copper-bismuth catalyst based on phase engineering regulation, characterized in that, Includes the following steps: 1) Preparation of Bi2S3 catalyst by hydrothermal method Add Bi(NO3)3·5H2O, C2H8N2 and C6H8O7·H2O to water and stir for 30-40 min to obtain solution A; dissolve C3H7NO2S in water and stir for 30-40 min to obtain solution B; Mix solution A and solution B and stir for 10-20 min, then transfer to a stainless steel autoclave. Heat to 170-190℃ and react for 18-20 h. After the reaction is complete, perform solid-liquid separation on the product. Wash and dry the obtained solid to obtain Bi2S3. 2) Synthesis of Cu2O-Bi2S3@Bi catalyst using sodium borohydride reduction method A mixture of Bi₂S₃ and Cu(NO₃)₂·3H₂O was added to water and stirred for 30-40 min. The molar ratio of Bi₂S₃ to Cu(NO₃)₂·3H₂O in the mixture was 0.10: 0.05-0.
30. Then, 0.01-0.08 g / mL of NaBH₄ solution was added dropwise. The reduction reaction was carried out for 4.5-5.5 h. After the reaction was completed, the product was separated into solid and liquid phases. The obtained solid was washed and dried to obtain the Cu₂O-Bi₂S₃@Bi catalyst.
2. The method for preparing a copper-bismuth catalyst based on phase engineering regulation according to claim 1, characterized in that, In step 1), when preparing solution A, the ratio of water, Bi(NO3)3·5H2O, C2H8N2 and C6H8O7·H2O is 10mL:0.48-0.52 g:0.75-0.85 mL:0.11-0.13 g.
3. The method for preparing a copper-bismuth catalyst based on phase engineering regulation according to claim 1, characterized in that, In step 1), when preparing solution B, the ratio of C3H7NO2S to water is 0.40-0.45 g : 5 mL.
4. The method for preparing a copper-bismuth catalyst based on phase engineering regulation according to claim 1, characterized in that, In step 1), the heating rate is 4.5-5.5℃ / min; the washing involves washing the solid obtained after solid-liquid separation with H2O and C2H5OH in sequence; the drying temperature is 55-65℃ and the time is 10-14 h.
5. The method for preparing a copper-bismuth catalyst based on phase engineering regulation according to claim 1, characterized in that, In step 2), the ratio of the total mass of the Bi2S3 and Cu(NO3)2·3H2O mixture, the amount of water, and the amount of NaBH4 solution used is 0.063-0.123g:100mL:10mL.
6. The method for preparing a copper-bismuth catalyst based on phase engineering regulation according to claim 1, characterized in that, In step 2), the washing involves washing the solid obtained after solid-liquid separation with water and anhydrous ethanol in sequence, and the drying temperature is 55-65℃ for 12-14 hours.
7. The Cu2O-Bi2S3@Bi catalyst obtained by the method according to any one of claims 1 to 8.
8. The application of the Cu2O-Bi2S3@Bi catalyst obtained by the method as described in claim 7 in the conversion of carbon dioxide in seawater.