An amorphous electrocatalyst, its preparation method and application

Abstract

The present invention belongs to the field of nanocatalysis technology, and particularly relates to an amorphous electrocatalyst and its preparation method and application. The preparation includes the following steps: Using a three-electrode system, nickel foam as the working electrode, silver / silver chloride as the reference electrode, and a graphite rod as the counter electrode, a metal nitrate precursor solution containing iron nitrate and cerium nitrate as the electrolyte, and performing constant current electrodeposition to obtain amorphous CeFeO<subgt;x< / subgt;H<subgt;y< / subgt; nanosheets supported on nickel foam. The present invention prepares large-area and high-quality amorphous CeFeO<subgt;x< / subgt;H<subgt;y< / subgt> nanosheets by a direct electrochemical deposition method. The prepared amorphous CeFeO<subgt;x< / subgt;H<subgt;y< / subgt> nanosheets can be well used as an efficient electrocatalyst for water electrolysis above room temperature. The method described in the present invention has a simple preparation process, is environmentally friendly, is convenient to operate, and has low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano catalysis, and particularly relates to an amorphous electrocatalyst, a preparation method thereof and an application thereof. Background Art

[0002] Hydrogen production by electrolyzing water is an important technology in green clean energy. Among them, the anodic oxygen evolution reaction has a high reaction overpotential due to its slow four-electron reaction process, which seriously affects the efficiency of electrolytic water decomposition, especially in industrial electrolytic water. Therefore, developing highly efficient and inexpensive oxygen evolution reaction catalysts is an important way to improve the efficiency of electrolyzing water.

[0003] Currently, various oxygen evolution catalysts have been developed, including hydroxides / hydroxyoxides, oxides, phosphides, selenides and sulfides. However, due to their limitations in catalytic activity and stability, these catalysts are still difficult to be used in practical industrial applications. Among them, amorphous hydroxyoxides have received extensive attention from researchers due to their good stability and corrosion resistance in alkaline media. In particular, amorphous iron-based oxides and hydroxyoxides have become one of the ideal candidate materials for the oxygen evolution reaction. To alleviate the sluggish kinetic problems of the oxygen evolution reaction, the catalytic activity and conductivity of electrocatalysts can be improved by element doping and constructing heterojunctions, but it is still difficult to maintain long-term stability at high current densities (>200 mA cm -2 ). Therefore, developing oxygen evolution catalysts with high stability, high efficiency and easy availability is of great significance for the application of iron-based hydroxyoxides in industrial electrolytic water. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an amorphous electrocatalyst, a preparation method thereof and an application thereof. The present invention provides a preparation of a large-area and high-quality amorphous CeFeO x H y electrocatalyst and its application in electrochemical water oxidation above room temperature. Large-area and high-quality amorphous CeFeO x H y nanosheets can be grown on nickel foam by a rapid and low-cost electrochemical deposition method. The CeFeO x H y nanosheets obtained in the present invention are evenly distributed and chemically stable. This method is easy to operate, requires simple equipment, and can be stably and efficiently applied to large-scale industrial electrolytic water above room temperature.

[0005] In a first aspect, the present invention provides a method for preparing an amorphous electrocatalyst, comprising the following steps: using a three-electrode system, with nickel foam as the working electrode, silver / silver chloride as the reference electrode, and a graphite rod as the counter electrode, and a metal nitrate precursor solution containing iron nitrate and cerium nitrate as the electrolyte, performing constant current electrodeposition to obtain amorphous CeFeO supported on nickel foam x H y nanosheets.

[0006] The present invention introduces cerium metal into iron oxyhydroxide to improve the stability and catalytic activity of the catalyst in strongly alkaline media, and synthesizes amorphous CeFeO x H y nanosheets by a one-step electrochemical deposition method, achieving excellent oxygen evolution activity and stability in alkaline media. Using the amorphous CeFeO x H y nanosheets supported on nickel foam prepared by the present invention as an electrocatalyst, for electrocatalytic water oxidation to prepare oxygen, the comprehensive electrocatalytic oxygen evolution effect is excellent, and it can be well applied to industrial electrolyzed water.

[0007] Preferably, the total concentration of iron nitrate and cerium nitrate in the metal nitrate precursor solution is 0.075 - 0.125 M, and the preferred concentration is 0.1 M; wherein the concentration ratio of iron nitrate to cerium nitrate is 0.9 - 0.99:0.01 - 0.10, preferably 0.95:0.05, 0.98:0.02, 0.99:0.01 or 0.90:0.10, and further preferably the concentration ratio is 0.95:0.05.

[0008] Preferably, the applied constant current is -10 to -30 mA; the electrodeposition time is preferably set to 5 - 25 min.

[0009] Further preferably, it further includes ultrasonically treating nickel foam in acetone, ethanol, HCl and deionized water for 5 - 20 min in sequence, and then performing vacuum drying.

[0010] More preferably, using a standard three-electrode system, placing nickel foam in acetone, ethanol, 1 M HCl and deionized water respectively for ultrasonic treatment for 5 - 15 min, preferably 10 min, and then vacuum drying at 50 - 60 °C, preferably 60 °C; then using the nickel foam as the working electrode, silver / silver chloride and graphite rod as the reference electrode and counter electrode respectively, using a metal nitrate precursor solution of iron nitrate and cerium nitrate with a total concentration of 0.1 M and a concentration ratio of 0.9 - 0.99:0.01 - 0.10 as the electrolyte, preferably a concentration ratio of 0.95:0.05, applying a constant current of -10 to -30 mA, preferably -20 mA, for 5 - 25 min, preferably 20 min of direct constant current electrodeposition, and performing washing after electrodeposition.

[0011] The present invention introduces cerium metal into iron oxyhydroxide to improve the stability and catalytic activity of the catalyst in a strong alkaline medium. Under the combined action of the concentrations of iron nitrate and cerium nitrate in the specific precursor solution optimized and screened in the present invention, the applied constant current, and the electrodeposition time, amorphous CeFeO x H y nanosheets are synthesized by electrochemistry deposition method, achieving a significant improvement in comprehensive properties such as oxygen evolution activity and stability in an alkaline medium. Its oxygen evolution overpotential is only 250 mV, and it can continuously operate for 300 hours at 100 mA cm -2 while maintaining good durability, and the potential is only 1.89 V (vs. RHE) at a high current density of 1 A cm -2 . In addition, the amorphous CeFeO x H y nanosheets and Pt-Ti mesh are used to construct a two-electrode water splitting device CeFeO x H y ||Pt-Ti, and its cell voltage is only 1.47 V, and it can stably operate for 200 hours at a current density of 10 mA cm -2 . When operating for 90 hours at 40 °C, the cell voltage of CeFeO x H y ||Pt-Ti only changes by 4%.

[0012] In a second aspect, the present invention provides an amorphous electrocatalyst obtained by the preparation method of the amorphous electrocatalyst described above.

[0013] Preferably, the amorphous CeFeO x H y nanosheets loaded on nickel foam have a loading of 3.3 - 3.7 mg cm -2 , preferably 3.5 mg cm -2 , the atomic ratio of Ce:Fe is 3.65 - 3.9:4 - 4.25, preferably 3.77:4.13; Fe 2 + / Fe 3+ ratio is 1:1.2.

[0014] In the present invention, by adopting an optimized preparation process and specific condition parameters, amorphous CeFeO x H y nanosheets with a specific loading and Ce-Fe atomic ratio can be prepared. By adjusting the concentration ratio of iron nitrate and cerium nitrate in the metal precursor solution used during electrodeposition, the Ce-Fe content is adjusted, and by adjusting the electrodeposition time, the loading of CeFeO x H y nanosheets is adjusted, significantly reducing the electrocatalytic oxygen evolution overpotential and reducing the energy consumption of electrochemical water oxidation for oxygen production.

[0015] As a further preferred technical solution of the method of the present invention, the amorphous CeFeO x H y nanosheets and its preparation method include the following steps: Using a standard three-electrode system, place nickel foam with a size of 4×2 cm 2 in acetone, ethanol, 1M HCl, and deionized water respectively for ultrasonic treatment for 10 minutes, and then place it in a vacuum drying oven at 60°C for drying. Use the washed and dried nickel foam as the working electrode, silver / silver chloride and graphite rod as the reference electrode and counter electrode respectively, use an iron-cerium precursor solution with a total concentration of 0.1M and a concentration ratio of iron nitrate to cerium nitrate of 0.95:0.05 as the electrolyte, and then perform direct constant current electrodeposition by applying a constant current of -20 mA for 20 minutes to obtain CeFeO x H y nanosheets loaded on nickel foam, with an atomic ratio of Ce:Fe:O of 3.77:4.13:50.14, and the loading amount of CeFeO x H y nanosheets is 3.5 mg cm -2 .

[0016] In the third aspect, the present invention provides the application of the amorphous electrocatalyst obtained by the preparation method of the amorphous electrocatalyst in electrochemical water oxidation.

[0017] Preferably, for the application of the amorphous electrocatalyst in electrochemical water oxidation, a two-electrode or three-electrode system is used, and the amorphous CeFeO x H y nanosheets loaded on nickel foam obtained by the preparation are used as the electrocatalyst to perform electrocatalytic water oxidation to prepare oxygen; preferably, a two-electrode system using the amorphous CeFeO x H y nanosheets as the anode is used to perform electrocatalytic water oxidation to prepare oxygen.

[0018] More preferably, with the amorphous CeFeO x H y nanosheets as the anode and a Pt-Ti mesh, ruthenium iridium oxide, or platinum sheet as the cathode, electrocatalytic water oxidation is carried out at a temperature of 25°C to 50°C to prepare oxygen; preferably, electrocatalytic water oxidation is carried out at a temperature of 40 to 45°C to prepare oxygen.

[0019] More preferably, the present invention provides a large-area and high-quality amorphous CeFeO x H y electrocatalyst prepared by the preparation method of the amorphous CeFeO x H yApplication of electrocatalyst in electrochemical water oxidation above room temperature. The beneficial effects of the present invention are at least as follows: The present invention prepares amorphous CeFeO x H y nanosheets by a direct electrochemical deposition method. The synthesis method has simple steps and low cost. The synthesized CeFeO x H y nanosheets are uniformly distributed on the nickel foam substrate and have high chemical stability. Using the prepared amorphous CeFeO x H y nanosheets as the electrocatalyst for water oxidation to produce oxygen under alkaline conditions, the overpotential is only 250 mV at a current density of 100 mA cm -2 . In addition, using amorphous CeFeO x H y nanosheets as the anode and a Pt-Ti mesh as the cathode, at a current density of 10 mA cm -2 under room temperature conditions, the CeFeO x H y ||Pt-Ti water electrolysis test can be stably continued for 200 hours. At 40 °C, at a current density of 10 mA cm -2 , the CeFeO x H<X y ||Pt-Ti cell can operate continuously for 90 hours, and the cell voltage only changes by 4%, which can be stably and efficiently applied to large-scale industrial electrolyzed water above room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention and the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a reaction schematic diagram of large-area amorphous CeFeO x H y nanosheets of the present invention;

[0022] Figure 2 It is a scanning electron microscope (SEM) (a) and transmission electron microscope (TEM) (b) photograph of amorphous CeFeO x H y nanosheets obtained by depositing for 20 min at -20 mA current in a solution with a total concentration of 0.1 M and a concentration ratio of iron nitrate to cerium nitrate of 0.95:0.05 in an embodiment of the present invention;

[0023] Figure 3XRD patterns of amorphous CeO, FeO, CeFeO nanosheets grown on nickel foam in the embodiments of the present invention x , FeO x H y and CeFeO x H y nanosheets;

[0024] Figure 4 X-ray photoelectron spectroscopy (XPS) of FeO, CeFeO nanosheets grown on nickel foam in the embodiments of the present invention x H y and CeFeO x H y nanosheets;

[0025] Figure 5 X-ray absorption spectroscopy (XAS) of CeFeO nanosheets (using Fe foil, FeOOH and Fe2O3 as reference samples) in the embodiments of the present invention x H y nanosheets;

[0026] Figure 6 Linear sweep voltammetry (LSV) curves of different CeFeO nanosheets prepared x H y nanosheets; (a) CeFeO nanosheets prepared by electrodeposition for 20 min in solutions of iron nitrate and cerium nitrate with different concentration ratios; (b) CeFeO nanosheets prepared by electrodeposition for different times in a solution of iron nitrate and cerium nitrate with a concentration ratio of 0.95:0.05 x H y nanosheets; x H y nanosheets;

[0027] Figure 7 Electrochemical impedance spectroscopy (EIS) of CeFeO nanosheets prepared in the embodiments of the present invention in an oxygen-saturated 1 M KOH solution x H y nanosheets;

[0028] Figure 8 Evaluation of the electrocatalytic oxygen evolution activity of CeFeO nanosheets in the embodiments of the present invention x H y nanosheets; Figure 9 Evaluation of the electrocatalytic oxygen evolution stability of CeFeO nanosheets in the embodiments of the present invention x H y nanosheets;

[0029] Figure 10 Using CeFeO as the anode and a Pt-Ti mesh as the cathode in the embodiments of the present invention x H y as the anode, a Pt-Ti mesh as the cathode, CeFeO x H y||Performance evaluation of Pt-Ti battery for electrolyzing water. Detailed implementation mode

[0030] In order to make the objectives, technical solutions and advantages of the embodiments of the invention clearer, the following describes clearly and completely the technical solutions in the embodiments of the invention with reference to the accompanying drawings in the embodiments of the invention. Obviously, the described embodiments are part of the embodiments of the invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the invention without creative efforts fall within the scope of protection of the invention.

[0031] Unless otherwise specified, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by known methods. For those embodiments without specific technologies or conditions indicated, they are all conventional methods or carried out according to the technologies or conditions described in the literature in this field, or according to the product specifications. For those reagents and instruments without the manufacturer indicated, they are all conventional products that can be obtained through regular channels.

[0032] The following will further illustrate the invention in combination with embodiments and the accompanying drawings.

[0033] Example 1

[0034] The high-quality large-area CeFeO x H y nanosheets provided in this example are prepared as follows:

[0035] (1) Place the nickel foam with a size of 4×2 cm 2 in acetone, ethanol, 1M HCl and deionized water respectively for ultrasonic treatment for 10 min, and then place it in a vacuum drying oven at 60 °C for drying.

[0036] (2) Adopt a standard three-electrode system. Place the nickel foam with a size of 4×2 cm 2 in acetone, ethanol, 1M HCl and deionized water respectively for ultrasonic treatment for 10 min, and then place it in a vacuum drying oven at 60 °C for drying. Use the washed and dried nickel foam as the working electrode, silver / silver chloride electrode and graphite rod as the reference electrode and counter electrode respectively, use the precursor solution of iron nitrate and cerium nitrate with a total concentration of 0.1M as the electrolyte, adjust the concentration ratio of iron nitrate and cerium nitrate and the electrodeposition time, and then carry out direct constant current electrodeposition by applying a constant current of -20 mA to obtain a series of CeFeO x H y nanosheets loaded on the nickel foam.

[0037] Comparative Example 1

[0038] Place the nickel foam with a size of 4×2 cm 2The nickel foam was sonicated in acetone, ethanol, 1M HCl, and deionized water for 10 min respectively, and then dried in a vacuum drying oven at 60 °C. Using a standard three-electrode system, the nickel foam with a size of 4×2 cm 2 The nickel foam was sonicated in acetone, ethanol, 1M HCl, and deionized water for 10 min respectively, and then dried in a vacuum drying oven at 60 °C. The washed and dried nickel foam was used as the working electrode, the silver / silver chloride electrode and the graphite rod were used as the reference electrode and the counter electrode respectively, and the electrolyte was 0.1M iron nitrate and 0.1M cerium nitrate precursor solutions respectively. Then, direct constant current electrodeposition was carried out by applying a constant current of -20 mA for 20 min to obtain FeO x H y 、CeO x nanosheets supported on nickel foam.

[0039] 8 mg of IrO2 powder was dispersed in 2 mL of a water / isopropanol solution with a volume ratio of 3:1, and 50 μL of Nafion solution was added, and then sonicated for 30 min. The obtained catalyst ink was dropped onto nickel foam (1×1 cm 2 ), and dried in an oven at 50 °C to obtain an IrO2 electrocatalyst supported on nickel foam, and the obtained IrO2 loading was 3.5 mg cm -2 .

[0040] Experimental Example 1

[0041] The series of high-quality large-area CeFeO x H y nanosheets prepared in the examples were applied to electrochemical water oxidation, and their electrocatalytic oxygen evolution activity and stability were evaluated:

[0042] (1) To screen out the optimal conditions for synthesizing CeFeO x H y nanosheets, first, at a total metal nitrate concentration of 0.1M, by adjusting the concentration ratios of iron nitrate and cerium nitrate to 0.95:0.05, 0.98:0.02, 0.99:0.01, and 0.9:0.1 respectively. Using the washed nickel foam as the working electrode, the graphite rod as the counter electrode, and the silver / silver chloride as the reference electrode, electrodeposition was carried out at a constant current of -20 mA for 20 min to obtain CeFeO with different Fe and Ce contents x H y nanosheets. Then, using the prepared CeFeO with different Fe and Ce contents x H y nanosheets as the working electrode, the mercury / mercuric oxide electrode and the graphite rod were used as the reference electrode and the counter electrode respectively. At room temperature, cyclic voltammetry tests (CV) were carried out in an oxygen-saturated 1M KOH solution at a scanning rate of 5 mV s-1 and record its overpotential for electrocatalytic oxygen evolution.

[0043] (2) To screen out the optimal conditions for synthesizing CeFeO x H y nanosheets, in a metal precursor solution with a total metal nitrate concentration of 0.1 M and a concentration ratio of iron nitrate to cerium nitrate of 0.95:0.05, using the washed nickel foam as the working electrode, a graphite rod as the counter electrode, and silver / silver chloride as the reference electrode, deposit for different times at a constant current of -20 mA to prepare CeFeO x H y nanosheets with different loadings. Then, using CeFeO x H y nanosheets with different loadings as the working electrode, a mercury / mercuric oxide electrode and a graphite rod as the reference electrode and the counter electrode respectively, perform cyclic voltammetry tests (CV) in an oxygen-saturated 1 M KOH solution at room temperature with a scanning rate of 5 mV s -1 , and record its overpotential for electrocatalytic oxygen evolution. (3) To evaluate the electrocatalytic oxygen evolution activity of amorphous CeFeO x H y nanosheets, compare amorphous FeO x H y nanosheets, CeO x nanosheets, IrO2 electrocatalyst with CeFeO x H y nanosheets. Using the amorphous FeO x H y supported on nickel foam, CeO x and CeFeO x H y nanosheets and IrO2 electrocatalyst prepared in Example 1 and Comparative Example 1 as the working electrode, a mercury / mercuric oxide electrode and a graphite rod as the reference electrode and the counter electrode respectively, perform linear sweep voltammetry tests and cyclic voltammetry tests in an oxygen-saturated 1 M KOH solution at room temperature with a scanning rate of 5 mV s-1, record the overpotentials for electrocatalytic oxygen evolution of amorphous FeO x H y 、CeO x and CeFeO x H y nanosheets and IrO2 electrocatalyst, and perform cyclic voltammetry tests at a scanning rate of 20 - 120 mV s -1 in the non-Faradaic region to obtain the double-layer capacitance. Before each test, perform 20 cyclic voltammetry scans at a scanning rate of 100 mV s -1 to stabilize the prepared catalyst. At a current density of 100 mAcm -2 ​x H y 、 CeO x 、 CeFeO x H y The oxygen evolution overpotentials of the H

[0044] (4) Using the as-prepared amorphous FeO x H y 、 CeO x and CeFeO x H y nanosheets and the IrO2 electrocatalyst as the working electrode, the mercury / mercuric oxide electrode and the graphite rod as the reference electrode and the counter electrode respectively, in an oxygen-saturated 1 M KOH solution at room temperature, electrochemical impedance spectroscopy tests were carried out. The test frequency range was 0.1 - 10 5 Hz, and the voltage was 1.48 V (vs. RHE).

[0045] (5) To evaluate the electrocatalytic oxygen evolution stability of the amorphous CeFeO x H y nanosheets in alkaline media. Using the as-prepared amorphous FeO x [[ID=�3]]H y and CeFeO x H y nanosheets as the working electrode, the mercury / mercuric oxide electrode and the graphite rod as the reference electrode and the counter electrode respectively, in an oxygen-saturated 1 M KOH solution at room temperature, cyclic voltammetry tests and linear sweep voltammetry tests were carried out. First, linear sweep voltammetry tests were carried out on the amorphous FeO x H y and CeFeO x H y nanosheets with a scan rate of 5 mV s -1 , then 3000 cyclic voltammetry scans were carried out respectively with a scan rate of 100 mV s -1 . After the cyclic voltammetry scans were completed, linear sweep voltammetry tests were carried out again with a scan rate of 5 mV s -1 , and the changes in the linear sweep voltammetry curves were compared after 3000 cyclic voltammetry tests. Finally, chronopotentiometry was measured at current densities of 100 mA cm -2 , 200 mA cm -2 and 300 mA cm -2 to evaluate its durability in the oxygen evolution reaction in a strongly alkaline solution.

[0046] (6) Using the as-prepared amorphous CeFeO x Hy The nanosheets serve as the anode, and the Pt-Ti mesh serves as the cathode. At a current density of 10 mA cm -2 , electrolysis of water is carried out in an oxygen-saturated 1 M KOH solution at room temperature and 40 °C respectively, and the curve of the cell voltage of CeFeO x H y ||Pt-Ti versus time is recorded. The following briefly explains its performance indicators in combination with Figures 1 - 8 some parts:

[0047] As Figure 1 shown is the reaction schematic diagram for preparing large-area amorphous CeFeO x H y nanosheets according to an exemplary embodiment of the present invention, using a standard three-electrode system;

[0048] As Figure 2 shown are the scanning electron microscope (SEM) (a) and transmission electron microscope (TEM) (b) photos of the amorphous CeFeO x H y nanosheets obtained by constant current deposition for 20 min at a current of -20 mA in a solution with a total metal precursor salt concentration of 0.1 M and a concentration ratio of iron nitrate to cerium nitrate of 0.95:0.05. It can be seen that the CeFeO x H y nanosheets are evenly distributed on the nickel foam;

[0049] As Figure 3 shown are the X-ray diffraction patterns (XRD) of amorphous CeO x , FeO x H y and CeFeO x H y nanosheets grown on nickel foam. By comparing with the standard PDF card of nickel foam, it can be found that CeO x , FeO x H y and CeFeO x H y nanosheets only exhibit the characteristic peaks of nickel foam, and no other peaks appear, indicating that the CeO x , FeO x H y and CeFeO x H y synthesized by the electrodeposition method are all amorphous;

[0050] As Figure 4 shown are FeO x H y and CeFeO x H yX-ray photoelectron spectroscopy (XPS) of the nanosheets, where FeO x H y ratio of Fe 2+ / Fe 3+ is 1.2:1. After introducing Ce, the Fe 2+ / Fe 3+ ratio drops to 1:1.2, indicating that the electronic structure of FeO x H y has changed;

[0051] As Figure 5 shown is the X-ray absorption spectrum (XAS) of the CeFeO x H y nanosheets, with Fe foil, FeOOH, and Fe2O3 as reference samples. Figure 5 a and b indicate that the Fe in the synthesized CeFeO x H y has an octahedral coordination with a +3 valence state. In addition, compared with Fe2O3 and FeOOH, the pre-edge intensity in the CeFeO x H y sample is slightly higher, indicating that the octahedral coordination at the Fe 3+ site may be distorted. Then, the Fourier-transform extended X-ray absorption fine structure (FT-EXAFS) is collected to study the local chemical coordination environment of CeFeO x H y . The Fe K-edge EXAFS analysis of the synthesized CeFeO x H y sample in the R space ( Figure 5 b) shows two main peaks at and that are the same as those of the Fe2O3 reference sample, respectively verifying the Fe-O and Fe-M (M = Fe / Ce) coordinations. Figure 5 c shows the crystal structure of FeO x H y before and after introducing Ce. It can be seen that the original regular orthorhombic crystal structure of FeO x H y becomes distorted after introducing Ce, and FeO x H y undergoes lattice distortion.

[0052] Figure 6 are the linear sweep voltammetry curves (LSV) of the as-prepared different CeFeO x H y nanosheets; Figure 6a shows CeFeO obtained by electrodepositing at -20 mA for 20 min in solutions of iron nitrate and cerium nitrate with different concentration ratios in a total metal precursor salt concentration of 0.1 M. x H y Cyclic voltammograms of the nanosheets. It can be seen that when the concentration ratio of iron nitrate to cerium nitrate is 0.95:0.05, at the same potential, the current density is the largest and the oxygen evolution overpotential is the smallest. Therefore, the optimal concentration ratio of Fe:Ce is 0.95:0.05. Figure 6 b shows CeFeO nanosheets obtained by electrodepositing for different times at a total metal precursor salt concentration of 0.1 M and an iron nitrate to cerium nitrate concentration ratio of 0.95:0.05. x H y nanosheets. It can be seen that when the electrodeposition time is 20 min, at the same potential, the current density is the largest and the oxygen evolution overpotential is the smallest. Therefore, the optimal electrodeposition time for preparing CeFeO x H y nanosheets is 20 min. Unless otherwise specified in the experimental verification of the present invention, CeFeO x H y nanosheets refer to the amorphous CeFeO nanosheets prepared under the above conditions (iron nitrate to cerium nitrate concentration ratio of 0.95:0.05, electrodeposition at -20 mA for 20 min). x H y nanosheets.

[0053] Figure 7 is FeO x H y 、Fe2O3、CeFeO x H y Electrochemical impedance spectra (EIS) of the nanosheets of FeO x H y 、Fe2O3、CeFeO in an oxygen-saturated 1 M KOH solution. It can be seen that the CeFeO x H y nanosheets obtained after introducing cerium have the smallest charge transfer resistance, and the charge transfer resistance is 1.185 Ω. The electron transfer on the CeFeO

[0054] Figure 8 is CeFeO x H y Activity evaluation of the electrocatalytic oxygen evolution of the nanosheets. Using the prepared CeFeO x H y nanosheets as the working electrode, a mercury / mercuric oxide electrode and a graphite rod are used as the reference electrode and the counter electrode respectively. Figure 8 a shows the measured cyclic voltammogram. After introducing cerium, the CeFeO x H y nanosheets have the smallest oxygen evolution overpotential;Figure 8 b is the corresponding electric double layer capacitance, CeFeO x H y The electric double layer capacitance of the nanosheets is larger, indicating that its electrochemically active area is larger, which is beneficial to the electrocatalytic oxygen evolution reaction.

[0055] Figure 9 is CeFeO x H y Evaluation of the stability of electrocatalytic oxygen evolution of the nanosheets. Figure 9 a is CeFeO x H y Linear sweep voltammetry curves of the nanosheets before and after 3000 cyclic voltammetry tests (CV) can be seen. After 3000 cyclic voltammetry tests, its linear sweep voltammetry curve is close to the curve before the test, and the electrocatalytic oxygen evolution current density does not decrease significantly, indicating that CeFeO x H y the nanosheets have excellent electrocatalytic oxygen evolution stability; Figure 9 b is FeO x H y Linear sweep voltammetry curves of the nanosheets before and after 3000 cyclic voltammetry tests can be seen. After 3000 cyclic voltammetry tests, FeO x H y the electrocatalytic oxygen evolution current of the nanosheets decreases significantly, indicating that in FeO x H y after introducing Ce, the oxygen evolution stability of the catalyst can be greatly improved; Figure 9 c is CeFeO x H y Chronopotentiometry test of the nanosheets can be seen. CeFeO x H y the nanosheets can operate stably for 300 hours at a current density of 100 mA cm -2 further indicating that CeFeO x H y the nanosheets have excellent oxygen evolution stability in strong alkaline media.

[0056] Figure 10 is CeFeO x H y || Performance evaluation of Pt-Ti electrolyzed water. Using CeFeO x H y as the anode and Pt-Ti mesh as the cathode, Figure 10 a is the linear sweep voltammetry curve of the test, indicating that at a current density of 10 mA cm -2 current density, CeFeO x H y||The voltage of the Pt-Ti cell is only 1.47 V (vs. RHE), far superior to that of the IrO2-Ti||Pt-Ti cell. Figure 10 b is CeFeO x H y For the anode and the Pt-Ti mesh cathode at room temperature, the current density is 10 mA cm -2 , and it can operate continuously for 200 hours. Figure 10 c is when the temperature is 40 °C, CeFeO x H y ||The Pt-Ti operates continuously for 90 hours, and the cell voltage only changes by 4%.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of an amorphous electrocatalyst, characterized in that, It includes the following steps: adopting a three-electrode system, using nickel foam as the working electrode, silver / silver chloride as the reference electrode, and a graphite rod as the counter electrode, and using a metal nitrate precursor solution of iron nitrate and cerium nitrate as the electrolyte, wherein the total concentration of iron nitrate and cerium nitrate in the metal nitrate precursor solution is 0.075 - 0.1 M; wherein the concentration ratio of iron nitrate to cerium nitrate is 0.95:0.05; constant current electrodeposition is carried out, and the applied constant current is -10 to -30 mA; the electrodeposition time is set to 5 to 25 min to obtain amorphous CeFeO x H y nanosheets.

2. The preparation method of the amorphous electrocatalyst according to claim 1, wherein, The total concentration of iron nitrate and cerium nitrate in the metal nitrate precursor solution is 0.1 M.

3. The preparation method of the amorphous electrocatalyst according to claim 1, characterized in that, It also includes ultrasonic treating the nickel foam in acetone, ethanol, HCl, and deionized water in sequence for 5 - 20 min, and then performing vacuum drying.

4. The preparation method of the amorphous electrocatalyst according to claim 1, characterized in that Adopting a standard three-electrode system, placing the nickel foam in acetone, ethanol, 1 M HCl, and deionized water respectively for ultrasonic treatment for 5 - 15 min, and then vacuum drying at 50 - 60 °C; then using the nickel foam as the working electrode, silver / silver chloride and the graphite rod as the reference electrode and the counter electrode respectively, using a precursor solution of iron nitrate and cerium nitrate with a total concentration of 0.1 M as the electrolyte, applying a constant current of -10 - -30 mA, and performing direct constant current electrodeposition for 5 - 25 min, and washing after electrodeposition.

5. The preparation method of the amorphous electrocatalyst according to claim 4, wherein Adopting a standard three-electrode system, placing the nickel foam in acetone, ethanol, 1 M HCl, and deionized water respectively for ultrasonic treatment for 10 min, and then vacuum drying at 60 °C; then using the nickel foam as the working electrode, silver / silver chloride and the graphite rod as the reference electrode and the counter electrode respectively, using a precursor solution of iron nitrate and cerium nitrate with a total concentration of 0.1 M as the electrolyte, applying a constant current of -20 mA, and performing direct constant current electrodeposition for 20 min, and washing after electrodeposition.

6. The amorphous electrocatalyst obtained by the preparation method of the amorphous electrocatalyst according to any one of claims 1 - 5.

7. The amorphous electrocatalyst according to claim 6, wherein The prepared amorphous CeFeO supported on nickel foam x H y The nanosheet loading is 3.3 - 3.7 mg / cm 2 .

8. The amorphous electrocatalyst according to claim 7, wherein The as-prepared amorphous CeFeO supported on nickel foam x H y The loading of the nanosheets is 3.5 mg / cm 2 , and the atomic ratio of Ce:Fe is 3.77:4.13; Fe 2+ / Fe 3+ The ratio is 1:1.

2.

9. The application of the amorphous electrocatalyst obtained by the preparation method of the amorphous electrocatalyst according to any one of claims 1 - 5 or the amorphous electrocatalyst according to any one of claims 6 - 8 in electrochemical alkaline water oxidation.

10. Use of the amorphous electrocatalyst according to claim 9 in electrochemical alkaline water oxidation, characterized in that, A two-electrode or three-electrode system was adopted to use the as-prepared amorphous CeFeO nanosheets supported on nickel foam as an electrocatalyst for electrocatalytic water oxidation to prepare oxygen. x H y ​ 11. Use of the amorphous electrocatalyst according to claim 10 in electrochemical alkaline water oxidation, characterized in that, Using the amorphous CeFeO x H y nanosheets as the anode in a two-electrode system for electrocatalytic water oxidation to produce oxygen.

12. Use of the amorphous electrocatalyst according to any one of claims 9-11 in electrochemical alkaline water oxidation, characterized in that, Using the amorphous CeFeO x H y nanosheets as the anode and a Pt-Ti mesh, ruthenium iridium oxide or a platinum sheet as the cathode, electrocatalytic water oxidation is carried out at a temperature of 25 °C to 50 °C to prepare oxygen.

13. Use of the amorphous electrocatalyst according to claim 12 in electrochemical alkaline water oxidation, characterized in that, Electrocatalytic water oxidation is carried out at a temperature of 40 - 45 °C to prepare oxygen.

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