Electron-rich copper bismuth nanomaterial, and preparation method and application thereof

Abstract

The application belongs to the technical field of electrocatalytic materials, and particularly relates to an electron-rich copper bismuth nanomaterial, a preparation method and application thereof. The electron-rich copper bismuth nanomaterial is obtained through simple anodic oxidation, in-situ pre-reduction and electric displacement reaction. The electron-rich copper bismuth nanomaterial composed of copper and bismuth is quickly prepared through the difference in electronegativity between metals. The electron-rich copper bismuth nanomaterial has the advantages of easy availability of raw materials, simple preparation method, green and environmentally-friendly process, low cost and the like, which are conducive to large-scale industrialization. The electron-rich copper bismuth nanomaterial can realize high current density and high selectivity of the reaction of reduction of carbon dioxide to formate in a three-electrode system and a double-electrode flow cell, and has long-term stability. In addition, the electron-rich copper bismuth nanomaterial can realize CO2RR under general pH in a double-cell flow cell, and can produce high FE (> 90%) formate (>= 100 mA cm ‑2 ) from CO2RR under a large current density.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic materials, and particularly relates to an electron-rich copper-bismuth nanomaterial and a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an admission or any kind of suggestion that this information forms the general prior art previously visualized by those working in the field.

[0003] The sharp rise in atmospheric carbon dioxide (CO2) concentration has triggered serious environmental and social problems. In order to alleviate CO2 release and reduce fossil consumption, one of the effective ways is to electrocatalyze CO2 reduction reaction (CO2RR), which can convert CO2 into chemicals and fuels by using renewable electricity. As the first step of electrocatalytic CO2RR, the effective activation of CO2 molecules on the surface of electrocatalysts is crucial. However, the high negative reduction voltage of CO2 / CO2 ·- , i.e. E 0 =-1.9 V vs. reversible hydrogen electrode (vs. RHE), makes the direct transfer of electrons to CO2 one of the most energy-demanding processes. In addition, CO2 molecules are prone to react with local OH - to produce CO3 2- or HCO3 - ions, which leads to inevitable loss of CO2 utilization and even may block the porous channels for CO2 transport in gas diffusion electrodes (GDEs). There are still problems such as poor selectivity and low stability of products in the electrocatalytic reduction of carbon dioxide at present, and the performance and stability of the electrocatalytic materials in the prior art are limited by the solution pH value. SUMMARY

[0004] In order to solve the problems in the prior art, the purpose of the present application is to provide an electron-rich copper-bismuth nanomaterial and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0006] In a first aspect, the present application provides a preparation method of an electron-rich copper-bismuth nanomaterial, comprising the following steps:

[0007] The metal copper is immersed in a hydroxide solution for anodic oxidation, then transferred to a potassium bicarbonate solution with carbon dioxide for cyclic voltammetry treatment, and then transferred to a bismuth salt solution for electroreplacement, and the metal copper surface material is collected to obtain the electron-rich copper-bismuth nanomaterial.

[0008] In a second aspect, the present application provides a preparation method of the electron-rich copper bismuth nanomaterial, which is obtained by the above-mentioned preparation method of the electron-rich copper bismuth nanomaterial.

[0009] In a third aspect, the present application provides an application of the above-mentioned electron-rich copper bismuth nanomaterial in electrocatalytic reduction of carbon dioxide.

[0010] In a fourth aspect, the present application provides a method for electrocatalytic reduction of carbon dioxide at general pH, which comprises the following steps:

[0011] The above-mentioned electron-rich copper bismuth nanomaterial is dissolved in an organic solvent to prepare an ink;

[0012] The ink is dropped on a carbon electrode as a cathode electrode;

[0013] The cathode electrode is placed in a flow cell for reduction of carbon dioxide under an acidic, neutral or alkaline solution.

[0014] In a fifth aspect, the present application provides a two-electrode battery, wherein the cathode of the two-electrode battery is a carbon electrode loaded with the above-mentioned electron-rich copper bismuth nanomaterial.

[0015] The above-mentioned one or more technical solutions of the present application have the following beneficial effects:

[0016] (1) The electron-rich copper bismuth nanomaterial is obtained by simple anodic oxidation, in-situ pre-reduction and electro-replacement reaction, which is quickly prepared by the difference in electronegativity between metals, and has the advantages of easy availability of raw materials, simple preparation method, green and environmentally friendly process, low cost and other advantages conducive to large-scale industrialization.

[0017] (2) The electron-rich copper bismuth nanomaterial in the present application has high current density and high selectivity in the reaction of reducing carbon dioxide to formate in a three-electrode system, and remains stable for more than 20 hours at -1V vs RHE, which has a broad prospect in practical application.

[0018] (3) The electron-rich copper bismuth nanomaterial in the present application realizes CO2RR at general pH in a two-cell flow cell, and can produce high FE (> 90%) formate (≥ 100 mA cm -2 ) from CO2RR at a large current density.

[0019] (4) The electron-rich copper bismuth nanomaterial in the present application has an electron-rich structure, which avoids the reaction of CO2 molecules with local OH - to produce CO3 2- or HCO3 - ions, thereby avoiding the reduction of CO2 utilization, and expanding the application of CO2RR at different pH. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 Scanning electron microscope images of electron-rich copper-bismuth nanomaterials from Examples 1-4;

[0022] Figure 2 This is a transmission electron microscope image of the electron-rich copper-bismuth nanomaterial of Example 2;

[0023] Figure 3 The elemental composition test diagrams for the electron-rich copper-bismuth nanomaterials of Examples 1-4 are shown.

[0024] Figure 4 The image is a scanning electron microscope image of HOD-Cu in Comparative Example 1.

[0025] Figure 5 The Bi 4f XPS spectra of the electron-rich copper bismuth nanomaterial of Example 2 and the electrically neutral bismuth of Comparative Example 2 are shown.

[0026] Figure 6 (A) Selectivity diagram of the electrocatalytic reduction of carbon dioxide to formate by electron-rich copper bismuth nanomaterials in Examples 1-4 at different voltages; (B) Selectivity diagram of the electrocatalytic reduction of carbon dioxide to formate by electron-rich copper bismuth nanomaterials in Example 2, HOD-Cu in Comparative Example 1, and neutral bismuth in Comparative Example 2 at different voltages.

[0027] Figure 7 The stability diagram of the electrocatalytic carbon dioxide reduction of the electron-rich copper bismuth nanomaterial in Example 2 is shown.

[0028] Figure 8 The selectivity and stability diagrams of the electron-rich copper bismuth nanomaterials of Example 2 for the electrocatalytic reduction of carbon dioxide to formate under different voltages in acidic, alkaline, and neutral solutions are shown.

[0029] Figure 9 This is a schematic diagram of a battery using hydrophobic carbon paper loaded with electron-rich copper-bismuth nanomaterials from Example 2 as the cathode and NiFe-LDH as the anode. Detailed Implementation

[0030] A first typical embodiment of the present invention provides a method for preparing electron-rich copper-bismuth nanomaterials, comprising the following steps:

[0031] The metal copper is immersed in a hydroxide solution for anodic oxidation, then transferred to a carbon dioxide-inhaled potassium bicarbonate solution for cyclic voltammetry treatment, and then transferred to a bismuth salt solution for electroreplacement, and the metal copper surface material is collected to obtain an electron-rich copper bismuth nanomaterial.

[0032] In one or more embodiments of the embodiment, the metal copper is copper foil, copper sheet, copper strip or copper wire, the hydroxide is one or more of sodium hydroxide, potassium hydroxide and ammonia water, and the concentration of the hydroxide is 4-6 mol / L.

[0033] In one or more embodiments of the embodiment, the current density of the anodic oxidation is 8-12 mA / cm 2 , and the anodic oxidation is stopped when the voltage changes at a speed of not less than 0.12 V vs. RHE / s;

[0034] The cycle range of the cyclic voltammetry is from -0.4 V to -1.2 V vs. RHE, and the cyclic voltammetry is stopped after the current density remains unchanged.

[0035] In one or more embodiments of the embodiment, the bismuth salt is one or more of bismuth chloride, bismuth nitrate, bismuth acetate and bismuth citrate, the concentration of the bismuth salt in the bismuth salt solution is 0.01-0.03 M, the solvent of the bismuth salt solution is dimethyl sulfoxide or dimethyl formamide, and the time of the electroreplacement is 0.5-12 h.

[0036] The composition, thickness and length of the electron-rich copper bismuth nanomaterial are regulated by adjusting the time of the electroreplacement reaction.

[0037] In a second typical embodiment of the present application, an electron-rich copper bismuth nanomaterial is characterized in that it is obtained by the preparation method of the electron-rich copper bismuth nanomaterial.

[0038] In a third typical embodiment of the present application, the electron-rich copper bismuth nanomaterial is applied to electrocatalytic reduction of carbon dioxide.

[0039] In a fourth typical embodiment of the present application, a general method for electrocatalytic reduction of carbon dioxide at a general pH comprises the following steps:

[0040] The electron-rich copper bismuth nanomaterial is dissolved in an organic solvent to prepare an ink;

[0041] The ink is dropped on a carbon electrode as a cathode electrode;

[0042] The cathode electrode is placed in a flow cell for reduction of carbon dioxide in an acidic, neutral or alkaline solution.

[0043] In one or more embodiments of the embodiment, the mass of the electron-rich copper bismuth nanomaterial is 3-5 mg.

[0044] The organic solvent is one or more of ethanol, methanol, and isopropanol, and the volume of the organic solvent is 300-500 μL;

[0045] The volume of the ink dropped on the carbon electrode is 20-200 μL, and the carbon electrode is one or more of hydrophobic carbon paper, carbon cloth, and carbon fiber felt;

[0046] The flow cell is a gas diffusion electrolysis cell or a membrane electrode cell.

[0047] In one or more embodiments of this embodiment, the pH of the acidic solution is 2-6, and the pH of the basic solution is 8-14.

[0048] The electron-rich copper bismuth nanomaterial can effectively activate carbon dioxide, enhance the adsorption of the formate intermediate OCHO, thereby reducing the influence of different proton sources at different pH values, greatly improving the selectivity and activity of carbon dioxide reduction to formate at a general pH value. At the same time, it avoids the waste of carbon dioxide and widens the road for actual industrialization.

[0049] In a fifth typical embodiment of the present application, a dual electrode cell, the cathode of the dual electrode cell is a carbon electrode loaded with the above electron-rich copper bismuth nanomaterial.

[0050] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples and comparative examples.

[0051] Example 1

[0052] (1) Dissolve 16.8 g of potassium hydroxide in 60 mL of water, and put copper foil into the solution to perform anodic oxidation on the copper foil at a current density of 10 mA / cm 2 The growth of the copper hydroxide nanowires is stopped when the voltage changes at a rate of 0.12 V vs. RHE / s.

[0053] (2) Dissolve 4.25 g of potassium bicarbonate in 85 mL of water, and pass CO2 for half an hour. Put the above copper hydroxide nanowires into the solution to perform cyclic voltammetry (from -0.4 V to -1.2 V vs. RHE). After the current density is stable and unchanged, the copper hydroxide nanowire array is completely converted into copper nanodendrites, which is denoted as HOD-Cu.

[0054] (3) Dissolve 0.33 g of bismuth chloride in 50 mL of dimethyl sulfoxide. Put HOD-Cu into the solution to perform electroreplacement for 0.5 h, collect the material on the surface of the copper foil, and obtain an electron-rich copper bismuth nanomaterial, which is denoted as 0.5-CuBi.

[0055] Example 2

[0056] (1) 16.8 g of potassium hydroxide was dissolved in 60 ml of water, and copper foil was put into the solution to perform anodic oxidation on the copper foil at a current density of 10 mA / cm 2 until the voltage stopped changing at a rate of 0.12 V vs. RHE / s. At this time, the growth of the cupric hydroxide nanowires was terminated

[0057] (2) 4.25 g of potassium bicarbonate was dissolved in 85 ml of water, and CO2 was bubbled into the solution for half an hour. The cupric hydroxide nanowires were put into the solution to perform cyclic voltammetry (from -0.4 V to -1.2 V vs. RHE). After the current density was stable, the cupric hydroxide nanowire array was completely converted into copper nanodendrites, which were denoted as HOD-Cu.

[0058] (3) 0.33 g of bismuth chloride was dissolved in 50 ml of dimethyl sulfoxide. The HOD-Cu was put into the solution to perform electroreplacement for 1 h, and the copper foil surface material was collected to obtain an electron-rich copper bismuth nanomaterial, which was denoted as 1-CuBi.

[0059] Example 3

[0060] (1) 16.8 g of potassium hydroxide was dissolved in 60 ml of water, and copper foil was put into the solution to perform anodic oxidation on the copper foil at a current density of 10 mA / cm 2 until the voltage stopped changing at a rate of 0.12 V vs. RHE / s. At this time, the growth of the cupric hydroxide nanowires was terminated

[0061] (2) 4.25 g of potassium bicarbonate was dissolved in 85 ml of water, and CO2 was bubbled into the solution for half an hour. The cupric hydroxide nanowires were put into the solution to perform cyclic voltammetry (from -0.4 V to -1.2 V vs. RHE). After the current density was stable, the cupric hydroxide nanowire array was completely converted into copper nanodendrites, which were denoted as HOD-Cu.

[0062] (3) 0.33 g of bismuth chloride was dissolved in 50 ml of dimethyl sulfoxide. The HOD-Cu was put into the solution to perform electroreplacement for 6 h, and the copper foil surface material was collected to obtain an electron-rich copper bismuth nanomaterial, which was denoted as 6-CuBi.

[0063] Example 4

[0064] (1) 16.8 g of potassium hydroxide was dissolved in 60 ml of water, and copper foil was put into the solution to perform anodic oxidation on the copper foil at a current density of 10 mA / cm 2 until the voltage stopped changing at a rate of 0.12 V vs. RHE / s. At this time, the growth of the cupric hydroxide nanowires was terminated

[0065] (2) Dissolve 4.25 g of potassium bicarbonate in 85 mL of water and purge with CO2 for half an hour. Place the above copper hydroxide nanowires into the solution for cyclic voltammetry (from -0.4 V to -1.2 V vs RHE). After the current density stabilizes, the copper hydroxide nanowire array is completely transformed into copper nanodendrites, denoted as HOD-Cu.

[0066] (3) Dissolve 0.33 g of bismuth chloride in 50 ml of dimethyl sulfoxide. Place HOD-Cu in the solution for electrodisplacement for 12 h, collect the material on the surface of the copper foil, and obtain electron-rich copper bismuth nanomaterial, denoted as 12-CuBi.

[0067] like Figure 1 As shown, the electron-rich copper-bismuth nanomaterials obtained in Examples 1-4 all exhibit a nanosheet structure morphology. Figure 2 As shown, the electron-rich copper-bismuth nanomaterial consists of bismuth nanosheets grown on copper nanodendrites. Figure 3 As shown, the bismuth content in electron-rich copper-bismuth nanomaterials increases with increasing electrodisplacement time.

[0068] Comparative Example 1

[0069] Unlike Example 1, step (3) is omitted, resulting in HOD-Cu. Figure 4 As shown, HOD-Cu exhibits a nanodendritic structure formed by the stacking of nanoparticles.

[0070] Comparative Example 2

[0071] (1) 2 mmol of Bi(NO3)3 and 20 mmol of KI were added to 50 mL of ultrapure water with stirring. The pH of the solution was then adjusted to 1.85 by adding diluted HNO3. After that, 20 mL of ethanol containing 0.23 M benzoquinone was added to the solution.

[0072] (2) The hydrophobic carbon paper was immersed in the solution obtained in step (1), and a constant potential deposition was performed at -0.2V vs. Ag / AgCl for 8 minutes to obtain BiOI nanosheets grown on the hydrophobic carbon paper. After natural drying, it was further reduced to a constant potential deposition at -0.6V vs. RHE in 0.5M KHCO3 electrolyte for 10 minutes, and the material on the surface of the carbon paper was collected to obtain electrically neutral bismuth.

[0073] like Figure 5 As shown, the bismuth binding energy of 1-CuBi in Example 2 is shifted to a lower binding energy compared to electrically neutral bismuth, and Bi 0 The increased proportion indicates an increase in the electron cloud density of 1-CuBi.

[0074] Example 5

[0075] Inks were prepared by dissolving 4 mg of the electron-rich copper-bismuth nanomaterials prepared in Examples 1-4, HOD-Cu in Comparative Example 1, and electrically neutral bismuth in Comparative Example 2 in 400 μL of dimethyl sulfoxide. The inks were then prepared in a 1×1 cm⁻¹ solution. 2 200 μL of the above ink was dropped onto hydrophobic carbon paper as reaction electrodes. Electrocatalytic carbon dioxide reduction experiments were carried out in a closed H-type reactor. Graphite carbon rods and Ag / AgCl were used as counter electrodes and reference electrodes, respectively. The electrolyte was a 0.5 M potassium bicarbonate solution saturated with carbon dioxide.

[0076] like Figure 6 As shown in Figure A, among the electron-rich copper-bismuth nanomaterials of Examples 1-4, 1-CuBi from Example 2 exhibited the best carbon dioxide reduction performance. Figure 6 As shown in B, compared with HOD-Cu in Comparative Example 1 and the electrically neutral bismuth in Comparative Example 2, 1-CuBi in Example 2 exhibits higher selectivity in reducing carbon dioxide to formate, demonstrating the excellent performance and stability of electron-rich copper-bismuth nanomaterials. Figure 7 As shown, the 1-CuBi of Example 2 can maintain high stability for more than 20 hours.

[0077] Example 6

[0078] 4 mg of the electron-rich copper-bismuth nanomaterial 1-CuBi from Example 2 was dissolved in 400 μL of dimethyl sulfoxide to prepare an ink. The ink was then applied at a 1×1 cm⁻¹ volume. 2 200 μL of ink was dropped onto hydrophobic carbon paper to serve as the cathode. NiFe-LDH was then prepared as the anode using the following steps:

[0079] Dissolve 0.5815g Ni(NO3)2·6H2O, 0.1405g FeSO4·7H2O, 0.37g NH4F, and 1.4994g urea in 40mL of water. (The last part, "2×3cm", appears to be a typo and can be omitted.) 2 The nickel foam was placed in a solution and then transferred to a PTFE-lined stainless steel autoclave. The autoclave was kept at 120°C for 8 hours, then removed, cooled to room temperature, washed with distilled water and ethanol, and air-dried.

[0080] The alkaline solution is a 1M potassium hydroxide solution with a pH of 14; the neutral solution is a 0.5M potassium bicarbonate solution with a pH of 7.3; and the acidic solution is a 1M potassium chloride solution with a pH adjusted to 2 using sulfuric acid.

[0081] The cathode and anode were placed in a gas diffusion electrolysis cell, and carbon dioxide reduction experiments were conducted using the alkaline, neutral, and acidic solutions, respectively.

[0082] like Figure 8As shown, 1-CuBi can realize carbon dioxide reduction to formate salt under acidic, neutral, and basic conditions, and the carbon dioxide reduction performance of 1-CuBi is not affected by the pH at a voltage of-1 to-1.2 V vs RHE. Further, the current density is maintained at 100 mA cm -2 Stability experiments were performed. As shown in Figure 8 As shown, the stability can be maintained for 8 h at each pH.

[0083] Further, the cathode and the anode were assembled into a membrane battery, and the battery structure is as shown in Figure 9

[0084] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for preparing electron-rich copper bismuth nanomaterials for electrocatalytic carbon dioxide reduction, characterized in that, The method comprises the following steps: The metal copper is immersed in a hydroxide solution for anodic oxidation, then transferred to a potassium bicarbonate solution with carbon dioxide for cyclic voltammetry treatment, and then transferred to a bismuth salt solution for electroreplacement, and the surface material of the metal copper is collected to obtain an electron-rich copper bismuth nanomaterial; The bismuth salt is one or more of bismuth chloride, bismuth nitrate, bismuth acetate and bismuth citrate, the concentration of the bismuth salt in the bismuth salt solution is 0.01-0.03 M, the solvent of the bismuth salt solution is dimethyl sulfoxide or dimethyl formamide, and the time of the electroreplacement is 0.5-12 h.

2. The method for preparing electron-rich copper-bismuth nanomaterials as described in claim 1, characterized in that, The metal copper is copper foil, copper sheet, copper strip or copper wire, the hydroxide is one or more of sodium hydroxide, potassium hydroxide and ammonia water, and the concentration of the hydroxide is 4-6 mol / L.

3. The method for preparing electron-rich copper-bismuth nanomaterials as described in claim 1, characterized in that, The current density for the anodization is 8-12 mA / cm 2 The anodization is stopped when the voltage is changed at a rate of not less than 0.12 V vs. RHE / s. The cyclic range of the cyclic voltammetry is from-0.4 V to-1.2 V vs RHE, and the cyclic voltammetry is stopped after the current density is stable.

4. An electron-rich copper bismuth nanomaterial, characterized in that, The electron-rich copper bismuth nanomaterial is obtained by the preparation method of any one of claims 1-3.

5. The electron-rich copper bismuth nanomaterial of claim 4 is applied to electrocatalytic reduction of carbon dioxide.

6. A method of general-purpose electrocatalytic carbon dioxide reduction at pH, characterized in that, The method comprises the following steps: The electron-rich copper bismuth nanomaterial of claim 4 is dissolved in an organic solvent to prepare an ink; The ink is dropped on a carbon electrode as a cathode electrode; The cathode electrode is placed in a flow cell for reduction of carbon dioxide in an acidic, neutral or alkaline solution.

7. The method of general-purpose electrocatalytic carbon dioxide reduction at pH according to claim 6, wherein, The mass of the electron-rich copper bismuth nanomaterial is 3-5 mg; The organic solvent is one or more of ethanol, methanol and isopropanol, and the volume of the organic solvent is 300-500 μL; The volume of the ink dropped on the carbon electrode is 20-200 μL, and the carbon electrode is one or more of hydrophobic carbon paper, carbon cloth and carbon fiber felt; The flow cell is a gas diffusion electrolysis cell or a membrane electrode cell.

8. The method of general-purpose electrocatalytic carbon dioxide reduction at pH according to claim 6, wherein, The pH of the acidic solution is 2-6, and the pH of the alkaline solution is 8-14.

9. A two-electrode cell, characterized by The cathode of the double electrode cell is a carbon electrode loaded with the electron-rich copper bismuth nanomaterial of claim 4.

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