Electrolyte modification method for regulating iron oxide electrocatalyst and preparation method and application thereof
The morphology of iron oxide electrocatalysts was controlled by electrolyte modification to form a layered nanosheet structure, which solved the conductivity and activity problems of iron-based oxide catalysts and improved the electrocatalytic performance, especially the efficiency in the oxygen evolution reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HENAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2022-10-28
- Publication Date
- 2026-06-19
AI Technical Summary
Iron-based oxide catalysts suffer from poor conductivity, few active sites, and low intrinsic activity, resulting in poor electrocatalytic performance.
An electrolyte modification method was used to control the preparation of iron oxide electrocatalysts. By using fluoroethylene carbonate (FEC) as an additive in lithium-ion batteries, the morphology of the iron oxide electrocatalyst was controlled to form a layered nanosheet structure, thereby increasing the number of active sites.
It improves the electrocatalytic performance of iron oxide electrocatalysts, especially in the oxygen evolution reaction, by reducing the overpotentials of oxygen evolution and hydrogen evolution, and improving the efficiency of electrocatalytic water splitting.
Smart Images
Figure CN115537844B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of catalyst preparation, and in particular relates to an electrolyte-modified iron oxide electrocatalyst, its preparation method, and its application. Background Technology
[0002] Electrolysis of water using renewable energy is a carbon-free hydrogen production technology with great industrial potential. The key lies in developing high-performance hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts, especially high-performance OER electrocatalysts, which can overcome the kinetic limitations of the rate-limiting step in the four-electron water oxidation reaction and improve the performance of electrocatalytic water splitting. Among many electrocatalytic materials, iron-based oxides (FeO) are superior to noble metal (Pt, Ru, Ir, etc.) catalysts. x Iron-based oxides (NF) have attracted widespread attention due to their abundant reserves, low price, and stable chemical properties. However, they suffer from poor conductivity, few active sites, and low intrinsic activity, resulting in relatively poor electrocatalytic performance.
[0003] In view of this, the present invention is hereby proposed. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides an electrolyte modification method for regulating iron oxide electrocatalysts and its preparation method. The electrolyte modification method gives the obtained iron oxide electrocatalyst a special morphology (layered nanosheet structure), which can effectively increase the number of active sites, thereby improving electrocatalytic performance.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] A method for preparing an electrolyte-modified iron oxide electrocatalyst includes the following steps:
[0007] (1) FeO x / NF sample preparation;
[0008] (2) FeO x / NF-FEC sample preparation: FeO prepared in step (1) was processed in a vacuum glove box. x A lithium-ion battery was assembled using NF as the cathode and a lithium sheet as the counter electrode. The electrolyte of the lithium-ion battery contained the additive fluoroethylene carbonate (FEC). The lithium battery was discharged for one week on a charge-discharge apparatus, and the electrode sheet was removed from the discharged lithium battery to obtain a FeO sample containing the FEC additive. x / NF-FEC is an electrocatalyst for iron oxide modified by electrolyte modification.
[0009] Furthermore, in step (1) FeO xThe preparation process of the / NF sample is as follows: Fe(NO3)3∙9H2O is dissolved in deionized water to form a homogeneous solution. Ammonium fluoride and urea are then added and stirred until homogeneous to obtain a mixed solution. The mixed solution is placed in a reaction vessel, along with a cleaned nickel mesh. The reaction vessel is then placed in an oven for hydrothermal reaction. After the reaction is completed, the sample is cooled to room temperature and then removed and cleaned. The cleaned sample is then placed in a muffle furnace for annealing to obtain the FeO sample. x / NF, 1 <x<1.5。
[0010] Furthermore, the molar ratio of Fe(NO3)3∙9H2O, ammonium fluoride, and urea is 1:1:2. Based on 1 mmol Fe(NO3)3∙9H2O, 70 mL of deionized water is required. The hydrothermal reaction temperature is 120℃, and the hydrothermal reaction time is 12 h.
[0011] Furthermore, the annealing conditions were as follows: first annealing at 60℃ for 10 hours, then annealing at 400℃ for 2 hours to obtain the FeO sample. x / NF.
[0012] Furthermore, the solvent in the electrolyte is ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1, the electrolyte is LiPF6 with a concentration of 1M, and the volume fraction of fluoroethylene carbonate (FEC) is 0.5 vol %-2 vol.
[0013] The present invention also provides an electrolyte-modified iron oxide electrocatalyst prepared by the above preparation method.
[0014] The application of the electrolyte modification method described in this invention for regulating the iron oxide electrocatalyst in the oxygen evolution reaction: FeO x / NF-FEC exhibits excellent electrocatalytic performance, especially at current densities reaching 200 mA•cm⁻¹. -2 The required oxygen evolution and hydrogen evolution overpotentials are 290 mV and 222 mV, respectively.
[0015] The typical preparation method of the electrolyte modification method for regulating the iron oxide electrocatalyst of the present invention is as follows:
[0016] FeO x / NF sample preparation
[0017] First, the nickel mesh was cleaned several times with hydrochloric acid, methanol, and deionized water. Then, 1 mmol of Fe(NO3)3∙9H2O was dissolved in 70 mL of deionized water to form a homogeneous solution, followed by the addition of 1 mmol of ammonium fluoride and 2 mmol of urea. After stirring for 1 hour, the homogeneous solution was poured into a reaction vessel, along with the cleaned nickel mesh. The reaction vessel was then placed in an oven at 120°C for 12 hours. Once the sample had cooled to room temperature, it was removed and cleaned with deionized water and alcohol. Finally, the cleaned sample was placed in a muffle furnace and annealed at 60°C for 10 hours, followed by annealing at 400°C for 2 hours to obtain the final FeO sample. x / NF.
[0018] FeO x Preparation of NF-FEC samples
[0019] Use a slicer to cut FeO x / NF was cut into electrode sheets, and the electrode sheets were dried in a vacuum drying oven at 120°C for 12 hours. After cooling to room temperature, they were removed. Subsequently, in a vacuum glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), FeO was used to dry the electrodes. x A lithium battery was assembled using NF as the cathode and a lithium sheet as the counter electrode (the lithium-ion battery electrolyte (LiPF6) contained 0.5 vol%-2 vol% fluoroethylene carbonate (FEC)). The lithium battery was then subjected to a one-week discharge test on a charge-discharge apparatus, and the electrode sheet was removed from the discharged lithium battery to obtain a sample containing the FEC additive (FeO). x / NF-FEC).
[0020] The beneficial effects of this invention: This invention uses an electrolyte modification method to regulate FeO x The morphology of / NF can be improved by using the additive FEC to enhance FeO. x / NF adapts to its volume changes during electrochemical conversion reactions, thus maintaining its original nanosheet structure, effectively inhibiting the decomposition of EC and DMC, forming a thin SEI film, increasing the exposure of active sites, and further improving FeO. x / NF's oxygen evolution and hydrogen evolution performance. Attached Figure Description
[0021] Figure 1 The FeO prepared in Example 1 x SEM image of / NF.
[0022] Figure 2 The FeO prepared in Example 1 x SEM image of / NF-FEC.
[0023] Figure 3 FeO x / NF、FeO x / NF-FEC1, FeO x / NF-FEC 0.5、 FeO x / NF-FEC2 and Comparative Example 1 sample FeO x Hydrogen evolution polarization curve of / NF-Li.
[0024] Figure 4 FeO x / NF、FeO x / NF-FEC1, FeO x / NF-FEC 0.5、 FeO x / NF-FEC2 and Comparative Example 1 sample FeO x Oxygen evolution polarization curve of / NF-Li. Detailed Implementation
[0025] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above-described invention. Example
[0026] (1) FeO x Preparation of / NF Samples: First, the nickel mesh was cleaned several times with hydrochloric acid, methanol, and deionized water. Then, 1 mmol Fe(NO3)3∙9H2O was dissolved in 70 mL of deionized water to form a homogeneous solution, followed by the addition of 1 mmol ammonium fluoride and 2 mmol urea. After stirring for 1 hour, the homogeneous solution was poured into a reaction vessel, along with the cleaned nickel mesh. The reaction vessel was then placed in an oven at 120°C for 12 hours. Once the sample had cooled to room temperature, it was removed and cleaned with deionized water and alcohol. Finally, the cleaned sample was placed in a muffle furnace and annealed at 60°C for 10 hours, followed by annealing at 400°C for 2 hours to obtain the final FeO sample. x / NF.
[0027] (2) FeO x / NF-FEC sample preparation: FeO was sliced using a slicer x / NF was cut into electrode sheets, which were then dried in a vacuum drying oven at 120°C for 12 hours and allowed to cool to room temperature before being removed. Subsequently, in a vacuum glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), FeO was used to dry the electrodes. xA lithium battery was assembled using fluoroethylene carbonate (FEC) as the cathode and a lithium sheet as the counter electrode. The electrolyte contained 1 vol% FEC, and the solvents were ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio. The electrolyte was LiPF6 at a concentration of 1 M. The lithium battery was then subjected to a one-week discharge test using a charge-discharge apparatus. The electrode sheet was then removed from the discharged battery to obtain a sample containing the FEC additive (FeO). x / NF-FEC1).
[0028] Figure 1 FeO prepared in this embodiment x SEM image of / NF, from Figure 1 It can be seen that the iron oxide growing on the nickel foam exhibits a nanosheet structure with a uniform morphology, forming an interwoven three-dimensional network.
[0029] Figure 2 FeO prepared in this embodiment x SEM images of / NF-FEC, from Figure 2 It can be seen that there is a layered nanosheet structure (small nanosheets are grown on the original nanosheets), and the original nanosheet structure is maintained.
[0030] Example 2 (FeO) x / NF-FEC 0.5 )
[0031] The only difference between this embodiment and Example 1 is the addition of 0.5 vol% fluoroethylene carbonate (FEC) to the lithium-ion battery electrolyte (LiPF6). The resulting sample is denoted as FeO. x / NF-FEC 0.5 .
[0032] Example 3 (FeO) x / NF-FEC2)
[0033] The only difference between this embodiment and Example 1 is the addition of 2 vol% fluoroethylene carbonate (FEC) to the lithium-ion battery electrolyte (LiPF6). The resulting sample is denoted as FeO. x / NF-FEC2.
[0034] Comparative Example 1
[0035] The only difference between Comparative Example 1 and Example 1 is that the lithium-ion battery electrolyte (LiPF6) does not contain fluoroethylene carbonate (FEC), thus yielding the electrocatalyst FeO. x / NF-Li.
[0036] Using a calomel electrode as the reference electrode, a platinum sheet electrode as the counter electrode, and FeO...x / NF or FeO x / NF-FEC1 (sample from Example 1) was used as the working electrode in a three-electrode test conducted in a 1 mol / L NaOH solution, and its polarization curve is shown below. Figure 3 As shown in Figure 4, it can be seen that FeO x / NF-FEC1 exhibits excellent electrocatalytic water splitting performance at a current density of 200 mA•cm⁻¹. -2 The required hydrogen evolution and oxygen evolution overpotentials are 222 mV and 290 mV, respectively, which are much smaller than those required for FeO. x / NF (479mV and 439mV) and FeO x / NF-Li (298mV and 311mV). This demonstrates that the electrolyte modification method uses FEC additives to modify FeO. x The morphology of FeO is affected, and its oxygen evolution and hydrogen evolution performance are influenced by morphology regulation. This invention uses an electrolyte modification method to modify FeO. x / NF-FEC has a unique morphology (layered nanosheet structure) and retains the original nanosheet structure better than additive-free FEC. This change can effectively increase the number of active sites, thereby improving electrocatalytic performance.
[0037] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for the preparation of an iron oxide electrocatalyst by electrolyte modification, characterized in that Includes the following steps: (1) FeO x Preparation of NF samples; (2) FeO x / NF-FEC sample preparation: FeO prepared in step (1) was processed in a vacuum glove box. x A lithium-ion battery was assembled using NF as the cathode and a lithium sheet as the counter electrode. The electrolyte of the lithium-ion battery contained the additive fluoroethylene carbonate (FEC). The lithium battery was discharged for one week on a charge-discharge apparatus, and the electrode sheet was removed from the discharged lithium battery to obtain a FeO sample containing the FEC additive. x / NF-FEC is an electrolyte-modified method for regulating iron oxide electrocatalysts; The volume fraction of fluoroethylene carbonate (FEC) is 0.5 vol %–2 vol.
2. The method for the preparation of iron oxide electrocatalyst controlled by electrolyte modification method according to claim 1, characterized in that: The step (1) FeO x The preparation process of the / NF sample is as follows: Fe(NO3)3∙9H2O was dissolved in deionized water to form a homogeneous solution. Ammonium fluoride and urea were then added and stirred until a homogeneous mixture was obtained. This mixture was placed in a reaction vessel along with a cleaned nickel mesh. The reaction vessel was then placed in an oven for hydrothermal reaction. After the reaction, the sample was cooled to room temperature, removed, and cleaned. The cleaned sample was then annealed in a muffle furnace to obtain FeO sample. x / NF, where 1 <x<1.5。 3. The preparation method of the iron oxide electrocatalyst by electrolyte modification according to claim 2, characterized in that: The molar ratio of Fe(NO3)3∙9H2O, ammonium fluoride, and urea is 1:1:
2. Based on 1 mmol Fe(NO3)3∙9H2O, 70 mL of deionized water is required. The hydrothermal reaction temperature is 120℃, and the hydrothermal reaction time is 12 h.
4. The method for the preparation of iron oxide electrocatalyst by electrolyte modification method according to claim 2, characterized in that: The annealing conditions were as follows: first annealing at 60℃ for 10 hours, then annealing at 400℃ for 2 hours to obtain the FeO sample. x / NF.
5. The method for the preparation of iron oxide electrocatalyst by electrolyte modification method as claimed in claim 1, wherein: The solvent in the electrolyte is ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1, and the electrolyte is LiPF6 with a concentration of 1M.
6. The electrolyte-modified iron oxide electrocatalyst prepared by the preparation method according to any one of claims 1-5.
7. The application of the electrolyte modification method described in claim 6 in regulating the iron oxide electrocatalyst in the water electrolysis reaction.
8. Use according to claim 7, characterized in that: FeO x / NF-FEC exhibits excellent electrocatalytic performance, especially at current densities reaching 200 mA•cm⁻¹. -2 The required oxygen evolution and hydrogen evolution overpotentials are 290 mV and 222 mV, respectively.