High-activity and high-stability amorphous complete water splitting catalyst as well as preparation and application thereof

Abstract

The invention discloses a high-activity and high-stability amorphous complete water splitting catalyst and a preparation method and application thereof in electrolyzed water. The high-activity and high-stability amorphous complete water splitting catalyst comprises a matrix and a dealloying layer wrapping the matrix, the matrix is an amorphous alloy, the chemical composition of the amorphous alloy is FeaCobNicPdRue, a, b, c, d and e represent atomic ratios, a is greater than or equal to 50 and less than or equal to 60, b is greater than or equal to 8 and less than or equal to 13, c is greater than or equal to 8 and less than or equal to 13, d is greater than or equal to 17 and less than or equal to 22, and 1lt is greater than or equal to 50 and less than or equal to 60; e < = 3, and a + b + c + d + e = 100; the dealloying layer is in an amorphous state and comprises Fe, Co, Ni, P, Ru and O, and Ru in the dealloying layer exists in a composite form of zero-valent ruthenium and ruthenium oxide; in terms of the total atomic number of Fe, Co, Ni, P and Ru being 100%, in the dealloying layer, the content of Fe atoms is 20%-40%, the content of Co atoms is 9%-15%, the content of Ni atoms is 9%-15%, the content of P atoms is 30%-50%, and the content of Ru atoms is 3%-10%.

Description

Technical Field

[0001] The present invention relates to the field of electrolyzed water catalysts, and particularly relates to a highly active and stable amorphous overall water splitting catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous growth of global energy demand and the increasing emphasis on environmental protection, the development of clean, efficient, and sustainable energy conversion technologies has become an urgent task. As an ideal clean energy carrier, hydrogen energy has attracted much attention due to its high energy density, renewable nature, and environmental friendliness. The electrolytic water hydrogen production technology is one of the important ways to realize hydrogen energy production, and has advantages such as zero carbon emissions and high hydrogen production purity compared with fossil fuel and industrial by-product hydrogen production technologies. However, the large-scale application of electrolytic water hydrogen production faces many challenges, and one of the most important challenges is to develop highly efficient, stable, and economical overall water splitting electrocatalysts.

[0003] Amorphous alloys exhibit excellent electrocatalytic performance due to their unique structural characteristics, such as high specific surface area, abundant active sites, and adjustable electronic states. In particular, phosphorus-iron-based amorphous alloys have attracted much attention due to their low cost and easy availability of raw materials. Iron and phosphorus are elements with abundant reserves on the earth, and the preparation process of their compounds is relatively simple and the cost is low, which gives phosphorus-iron-based amorphous alloys significant economic advantages in large-scale applications. In addition, phosphorus-iron-based amorphous alloys show good electrocatalytic activity under alkaline conditions and can effectively reduce the overpotential of the electrolyzed water reaction, thereby improving the electrolysis efficiency.

[0004] However, despite the many advantages of phosphorus-iron-based amorphous alloys, they still face some challenges in practical applications. First, the activity of pure phosphorus-iron-based amorphous alloys still needs to be further improved. In the electrolyzed water reaction, the adsorption and desorption processes of reaction intermediates play a decisive role in the activity of the catalyst. The electronic structure and surface properties of pure phosphorus-iron-based amorphous alloys limit their adsorption ability for reaction intermediates, resulting in a relatively high reaction overpotential. Second, the stability of phosphorus-iron-based amorphous alloys is insufficient. In alkaline electrolytes, long-term operation may lead to passivation of the catalyst surface or instability of the structure, thereby reducing its catalytic performance. Therefore, how to improve the activity and stability of phosphorus-iron-based amorphous alloys while maintaining low cost has become an important research direction.

[0005] To overcome the limitations of pure iron - phosphorus - based amorphous alloy catalysts, researchers have attempted to optimize the catalyst performance by doping noble metals. Noble metals such as platinum (Pt), ruthenium (Ru), etc. are widely used in the research of electrocatalysts for water electrolysis due to their unique electronic structures and excellent catalytic properties. However, the high price of noble metals such as platinum limits their large - scale application. In contrast, ruthenium (Ru), as a relatively inexpensive noble metal, has a platinum - like electronic structure, not only has high electrochemical activity, but also can significantly improve the stability and durability of the catalyst.

[0006] To further improve the activity of the catalyst and optimize the electronic structure and coordination environment of the active site Ru, the number of active sites can be increased by dealloying (selectively dissolving active elements in the alloy), providing more reaction sites for the water decomposition reaction. At the same time, the amorphous structure can still be maintained after dealloying, without grain boundaries, defects, and crystal plane differences in crystalline materials, and the distribution of active sites is more uniform and dense. Currently, some electrocatalysts that add electronic structure regulation to the active sites have been applied to the water electrolysis process, but such catalysts studied so far basically cannot achieve low cost and stable operation at a large current density of industrial grade (500 mA / cm 2 ).

[0007] Therefore, it is very attractive to prepare amorphous alloy overall water - splitting electrocatalysts that can be efficiently and stably applied in strong alkaline media, which can simplify the system and reduce costs. Summary of the Invention

[0008] Aiming at the above - mentioned technical problems and deficiencies in the art, the present invention provides a high - activity and high - stability amorphous overall water - splitting catalyst, its preparation method and application. The catalyst of the present invention has excellent hydrogen - evolution and oxygen - evolution performance as an electrocatalyst, and can achieve rapid and efficient water electrolysis and stable water electrolysis at a large current density.

[0009] The specific technical solutions are as follows:

[0010] [1] A high - activity and high - stability amorphous overall water - splitting catalyst, comprising a matrix and a dealloyed layer wrapping the matrix;

[0011] The matrix is an amorphous alloy, and the chemical composition of the amorphous alloy is Fe a Co b Ni c P d Ru e, where a, b, c, d, and e all represent atomic ratios, and 50 ≤ a ≤ 60 (for example, a = 57, a = 58, etc.), 8 ≤ b ≤ 13 (for example, b = 10, etc.), 8 ≤ c ≤ 13 (for example, c = 10, etc.), 17 ≤ d ≤ 22 (for example, d = 20, etc.), 0 < e ≤ 3 (for example, e = 2, e = 3, etc.), and a + b + c + d + e = 100;

[0012] The dealloyed layer is amorphous, and its constituent elements include Fe, Co, Ni, P, Ru, and O. Moreover, Ru in the dealloyed layer exists in the form of a composite of zero-valent ruthenium and ruthenium oxide (which can be denoted as Ru-RuO x , 0 < x ≤ 2);

[0013] Based on the total atomic number of Fe, Co, Ni, P, and Ru being 100%, in the dealloyed layer, the Fe atom content is 20% - 40%, the Co atom content is 9% - 15%, the Ni atom content is 9% - 15%, the P atom content is 30% - 50%, and the Ru atom content is 3% - 10%.

[0014] In the highly active and highly stable amorphous overall water splitting catalyst of the present invention, the amorphous Ru-RuO x is directly exposed on the catalyst surface, creating more reactive sites and enabling more efficient electrocatalytic overall water splitting. Compared with crystalline Ru and RuO x , the reactive sites are more abundant, and the structure self-healing ability during the reaction process is stronger. Therefore, it has better catalytic performance (including catalytic activity and stability). At the same time, compared with existing C-supported catalysts such as Pt / C, it has higher reaction activity and stability, and the sample preparation process is simple and the cost is low.

[0015] In the highly active and highly stable amorphous overall water splitting catalyst of the present invention, the amorphous Ru-RuO x is stably stationed in the amorphous matrix (the amorphous Ru-RuO x serves as the main reactive site, is not easily detached, and has high stability). Therefore, it can still maintain excellent catalytic performance after reacting for a long time at a large current density of 500 mA / cm 2 or above.

[0016] The Fe, Co, Ni, and P elements provided by the present invention provide a large number of electrons to Ru-RuO x . Consequently, compared with the prior art, the amorphous Ru-RuO x in the present invention can obtain more electrons for overall water splitting, and thus can perform overall water splitting more efficiently, improving the electrocatalytic hydrogen production and oxygen production performance and stability.

[0017] In some embodiments, the dealloyed layer contains medium-range structures. The presence of the medium-range structures enables the dealloyed layer to better withstand the volume changes brought about by redox reactions during the electrocatalytic process. Therefore, the prepared catalyst has higher stability.

[0018] In some embodiments, the content of zero-valent ruthenium in the Ru element on the surface of the dealloyed layer is greater than the content of positively-valent ruthenium in ruthenium oxide.

[0019] In some embodiments, the thickness of the dealloyed layer is 3 to 5 micrometers, and further can be 3 to 4 micrometers.

[0020] In some embodiments, the dealloyed layer is formed by electrochemically etching the amorphous alloy.

[0021] In the present invention, a large amount of Fe on the surface of the amorphous alloy is corroded by electrochemical etching, and part of Co and Ni are corroded away, so that the surface active layer of the catalyst has more P and Ru elements. The catalyst includes an amorphous alloy structure in the bulk phase and an amorphous dealloyed layer on the surface, making the interior of the surface dealloyed layer rich in active sites. Due to the action of electrochemical etching, the electronic structures of various elements are rearranged, promoting the transfer of electrons from Fe, Co, Ni, P to amorphous Ru-RuO x , optimizing the catalytic activity of Ru-RuO x , accelerating the catalytic reaction kinetics. At the same time, since the etching solution does not corrode Ru and P, highly catalytically active Ru-RuO x is highly enriched on the surface of the P-rich catalyst, which gives the catalyst excellent overall water splitting activity and stability.

[0022] In some embodiments, the electrochemical etching may specifically include: immersing the amorphous alloy in an etching solution for electrochemical etching treatment to form the dealloyed layer.

[0023] In some embodiments, the electrochemical etching uses a three-electrode system, and the amorphous alloy serves as the working electrode. The counter electrode and reference electrode in the three-electrode system can use commonly used materials in the field. For example, the counter electrode can be graphite, etc., and the reference electrode can be Ag / AgCl, etc.

[0024] In some embodiments, the etching solution is an acid solution with a concentration of 1.5 to 2.5 mol / L (such as 2 mol / L, etc.).

[0025] In some embodiments, the etching solution includes at least one of hydrochloric acid, sulfuric acid, and aqua regia.

[0026] In some embodiments, the voltage for the electrochemical etching treatment is the voltage corresponding to the maximum etching current.

[0027] In some embodiments, the voltage of the electrochemical etching treatment is 0.3 - 0.45V, such as 0.36V, 0.42V, etc.

[0028] In some embodiments, the time of the electrochemical etching treatment does not exceed 200s, such as 60s, etc.

[0029] In some embodiments, washing and drying operations are also performed after the electrochemical etching treatment. The specific steps of the washing can be: repeatedly rinsing the product after the electrochemical etching treatment with deionized water and ethanol in sequence. The drying temperature can be 20 - 30°C, and the time can be 10 - 30 min.

[0030] [2] According to the preparation method of the highly active and highly stable amorphous overall water splitting catalyst described in [1], the amorphous alloy is immersed in the etching solution for electrochemical etching treatment to form the dealloyed layer, and the highly active and highly stable amorphous overall water splitting catalyst is obtained.

[0031] The present invention does not particularly limit the method for obtaining the amorphous alloy, and the amorphous alloy can be obtained according to conventional methods in the art such as the single-roll melt spinning method. The raw materials of the amorphous alloy can include metal elements of Fe, Co, Ni, Ru with a purity not less than 99.9 wt% and FeP compounds. The master alloy ingot of the amorphous alloy can be obtained by melting in an inert atmosphere, and the inert atmosphere refers to a gas atmosphere that does not participate in the reaction, specifically, it can be a noble gas such as argon. In the single-roll melt spinning method, the roll speed can be 40 - 50 m / s.

[0032] In some embodiments, the electrochemical etching uses a three-electrode system, and the amorphous alloy serves as the working electrode. The counter electrode and reference electrode in the three-electrode system can use commonly used materials in the field. For example, the counter electrode can be graphite, etc., and the reference electrode can be Ag / AgCl, etc.

[0033] In some embodiments, the etching solution is an acid solution with a concentration of 1.5 - 2.5 mol / L (such as 2 mol / L, etc.).

[0034] In some embodiments, the etching solution includes at least one of hydrochloric acid, sulfuric acid, and aqua regia.

[0035] In some embodiments, the voltage of the electrochemical etching treatment uses the voltage corresponding to the maximum etching current.

[0036] In some embodiments, the voltage of the electrochemical etching treatment is 0.3 - 0.45V, such as 0.36V, 0.42V, etc.

[0037] In some embodiments, the time of the electrochemical etching treatment does not exceed 200s, such as 60s, etc.

[0038] In some embodiments, washing and drying operations are also performed after the electrochemical etching treatment. The specific steps of the washing can be: repeatedly rinsing the product after the electrochemical etching treatment with deionized water and ethanol in sequence. The drying temperature can be 20 - 30 °C, and the time can be 10 - 30 min.

[0039] [3] Application of the highly active and highly stable amorphous overall water splitting catalyst described in [1] in electrolyzed water. The highly active and highly stable amorphous overall water splitting catalyst of the present invention can be used in an alkaline electrolytic cell. The highly active and highly stable amorphous overall water splitting catalyst of the present invention can be directly used as the cathode and / or anode of the alkaline electrolytic cell, both having good hydrogen evolution and oxygen evolution reaction activities and good stability, that is, the catalyst prepared by the present invention can effectively achieve stable and efficient overall water splitting. The highly active and highly stable amorphous overall water splitting catalyst prepared in the present invention has the property of self-support and can be directly used as a working electrode.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1) The present invention uses an amorphous alloy formed by a specific element ratio combination, and on this basis, through an electrochemical dealloying process, Fe, Co, Ni, and P are transformed into amorphous Ru - RuO x providing more electrons, such that the Ru - RuO in the amorphous catalyst provided by the present invention x has its electronic structure optimized, improving its reaction activity as an active site. At the same time, due to the relatively large medium-range order structure in the amorphous overall water splitting catalyst, the amorphous overall water splitting catalyst has more excellent overall water splitting activity and stability.

[0042] 2) The highly active and highly stable amorphous overall water splitting catalyst provided by the present invention has many active reaction sites, and its catalytic activity is superior to that of commercial noble metal catalysts.

[0043] 3) The preparation method provided by the present invention corrodes metal elements by using electrochemical etching, enabling as much Ru as possible to be exposed to the outside, greatly reducing the preparation cost of raw materials. Good catalytic performance can be achieved with less Ru, and the catalyst preparation process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 XRD pattern of the amorphous electrolyzed water catalyst prepared in Comparative Example 1 of the present invention;

[0045] Figure 2 SEM cross-sectional micrograph of the amorphous overall water splitting catalyst prepared in Example 1 of the present invention;

[0046] Figure 3SEM surface microscopic morphology photograph of the amorphous overall water splitting catalyst prepared in Example 1 of the present invention;

[0047] Figure 4 Transmission electron microscopy (TEM) microscopic morphology photograph and element distribution map of the amorphous electrolytic water catalyst prepared in Comparative Example 1 of the present invention;

[0048] Figure 5 Transmission electron microscopy (TEM) microscopic morphology photograph and element distribution map of the amorphous overall water splitting catalyst prepared in Example 1 of the present invention;

[0049] Figure 6 X-ray photoelectron spectroscopy (XPS) characterization diagrams before and after electrochemical etching of the alloy strip precursor in Example 1 of the present invention and after CV activation after etching;

[0050] Figure 7 Test result diagrams of the hydrogen evolution performance of the catalysts respectively prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention;

[0051] Figure 8 Test result diagrams of the oxygen evolution performance of the catalysts respectively prepared in Example 1, Comparative Example 1 and Comparative Example 3 of the present invention;

[0052] Figure 9 Test result diagrams of the overall water splitting performance of the catalyst of Example 1, the catalyst of Comparative Example 1 and the catalysts of Comparative Example 2 and Comparative Example 3 as the anode and cathode;

[0053] Figure 10 Test result diagram of the hydrogen evolution stability of the amorphous overall water splitting catalyst prepared in Example 1 of the present invention;

[0054] Figure 11 Test result diagram of the oxygen evolution stability of the amorphous overall water splitting catalyst prepared in Example 1 of the present invention;

[0055] Figure 12 Test result diagram of the overall water splitting stability of the amorphous overall water splitting catalyst prepared in Example 1 of the present invention. Detailed implementation manners

[0056] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The operating methods without specific conditions noted in the following embodiments are generally in accordance with conventional conditions or in accordance with the conditions recommended by the manufacturer.

[0057] Example 1:

[0058] This example provides a preparation method of a highly active and highly stable amorphous overall water splitting catalyst, including the steps:

[0059] (1) Select Fe, Co, Ni, Ru metal elements with a purity greater than 99.9 wt% and FeP compounds, and mix them according to the atomic ratio of Fe 58 Co 10 Ni 10 P 20 Ru2. Induction melting of the alloying elements in the above ratio is carried out in an argon (Ar) protective atmosphere to uniformly mix the elements. After casting and cooling, a master alloy ingot is obtained.

[0060] (2) Then, using a vacuum spinning equipment, the master alloy ingot is induction remelted in a quartz tube, and then sprayed onto a copper roller with a linear velocity of 45 m / s through an instantaneous pressure difference of 0.04 MPa to form a precursor of an amorphous alloy strip. The thickness of the strip is 20 - 30 μm, the width is 1 - 2 mm, and it has a metallic luster.

[0061] (3) Immerse the precursor of the alloy strip as the working electrode into a fresh sulfuric acid solution (molar concentration is 2 mol / L) for corrosion treatment. The counter electrode is a graphite rod, and the reference electrode is Ag / AgCl. The treatment is carried out at a voltage of 0.42 V for 1 min. After the electrochemical etching treatment, the obtained alloy electrocatalyst is repeatedly rinsed with deionized water and absolute ethanol at least three times, and then placed in an oven and dried for 20 min at a temperature of 30 °C to obtain a highly active and highly stable amorphous overall water splitting catalyst.

[0062] Example 2:

[0063] This example provides a preparation method of a highly active and highly stable amorphous overall water splitting catalyst, including the steps:

[0064] (1) Select Fe, Co, Ni, Ru metal elements with a purity greater than 99.9 wt% and FeP compounds, and mix them according to the atomic ratio of Fe 57 Co 10 Ni 10 P 20 Ru3. Induction melting of the alloying elements in the above ratio is carried out in an argon (Ar) protective atmosphere to uniformly mix the elements. After casting and cooling, a master alloy ingot is obtained.

[0065] (2) Then, using a vacuum spinning equipment, the master alloy ingot is induction remelted in a quartz tube, and then sprayed onto a copper roller with a linear velocity of 45 m / s through an instantaneous pressure difference of 0.04 MPa to form a precursor of an amorphous alloy strip. The thickness of the strip is 20 - 30 μm, the width is 1 - 2 mm, and it has a metallic luster.

[0066] (3) Immerse the alloy strip precursor as the working electrode into a fresh sulfuric acid solution (molar concentration is 2 mol / L) for corrosion treatment. The counter electrode is a graphite rod, and the reference electrode is Ag / AgCl. Treat at a voltage of 0.36 V for 1 min. After the electrochemical etching treatment, the obtained alloy electrocatalyst is repeatedly rinsed with deionized water and absolute ethanol at least three times, and then placed in an oven to dry for 20 min at a temperature of 30 °C to obtain a highly active and highly stable amorphous overall water splitting catalyst.

[0067] Comparative Example 1:

[0068] The difference from Example 1 is only that step (3) is not carried out, and the rest are the same, that is, the amorphous alloy strip precursor obtained in step (2) is directly used as the amorphous electrolytic water catalyst.

[0069] Comparative Example 2:

[0070] The catalyst provided in this comparative example is a Pt / C catalyst. The preparation method of the working electrode of the Pt / C catalyst is to disperse 5 mg of commercial Pt / C powder catalyst (containing 20 wt% Pt) in a mixture of 950 μL of ethanol and 50 μL of Nafion, and then ultrasonically treat for 30 min to form a uniform catalyst suspension. Transfer 5 μL of the catalyst suspension to a glassy carbon electrode with a diameter of 3 mm (0.07 cm 2 ) and then dry at room temperature to obtain a Pt / C working electrode (i.e., the electrocatalyst). The loading amount of the Pt / C powder catalyst is 0.357 mg / cm 2 .

[0071] Comparative Example 3:

[0072] The catalyst provided in this comparative example is a RuO2 catalyst. The preparation method of the working electrode of the RuO2 catalyst is to disperse 5 mg of commercial RuO2 powder catalyst in a mixture of 950 μL of ethanol and 50 μL of Nafion, and then ultrasonically treat for 30 min to form a uniform catalyst suspension. Transfer 5 μL of the catalyst suspension to a glassy carbon electrode with a diameter of 3 mm (0.07 cm 2 ) and then dry at room temperature to obtain a RuO2 working electrode (i.e., the electrocatalyst). The loading amount of the RuO2 powder catalyst is 0.357 mg / cm 2 .

[0073] Performance analysis:

[0074] As Figure 1 shown, the FeCoNiPRu alloy precursor prepared in Comparative Example 1 (i.e., the main body of the catalyst in Example 1) is an amorphous structure.

[0075] As Figure 2As shown, the amorphous overall water splitting catalyst prepared in Example 1 has a composite structure of a dealloyed layer - matrix amorphous layer - dealloyed layer. The thickness of the upper and lower dealloyed layers is 3 - 4 μm. The elemental analysis results at different positions of the dealloyed layer show that the constituent elements of the dealloyed layer include Fe, Co, Ni, P, Ru, and O. And based on the total atomic number of Fe, Co, Ni, P, and Ru being 100%, the Fe atomic content in the dealloyed layer is 27.94% - 32.36%, the Co atomic content is 12.23% - 13.28%, the Ni atomic content is 10.65% - 11.02%, the P atomic content is 37.86% - 42.92%, and the Ru atomic content is 6.26% - 5.48%.

[0076] As Figure 3 shown, there are some pitting pits due to element removal on the surface of the amorphous overall water splitting catalyst prepared in Example 1, and the rest are flat structures, which are very similar to the surface of the normal amorphous strip before electrochemical etching.

[0077] As Figure 4 shown, the amorphous electrolytic water catalyst prepared in Comparative Example 1 has an amorphous structure, and the elements Fe, Co, Ni, P, and Ru are evenly distributed.

[0078] As Figure 5 shown, in Example 1, after electroetching in the etching solution, the re - constructed dealloyed layer on the surface is still in an amorphous structure and contains some medium - range order, and the element distribution is uniform.

[0079] As Figure 6 shown, through X - ray photoelectron spectroscopy characterization, compared with the precursor, after electrochemical etching of the alloy strip precursor in Example 1 and after activation of the electrochemically etched alloy strip by cyclic voltammetry (CV) (cycling 5 times at a scan rate of 50 mV / s at positive voltages of 0 - 0.6 V and negative voltages of - 1 - - 1.5 V respectively), the electrons of Fe, Co, Ni, and P in the obtained catalyst shift towards higher binding energies, and an Ru - RuO x signal appears in the Ru 3p energy spectrum after etching. After CV activation, this peak shifts towards lower binding energies, indicating that the area around Ru - RuO x is richer in electrons, improving the electrocatalytic efficiency and stability.

[0080] In the following hydrogen evolution, oxygen evolution, and overall water splitting performance and stability tests, the catalysts of each example and comparative example are pre - treated through the above - mentioned CV activation process.

[0081] (I) Hydrogen evolution and oxygen evolution performance test of amorphous overall water splitting electrocatalyst:

[0082] The present invention uses a Zahner Zennium electrochemical workstation and adopts a three-electrode system: The catalyst samples prepared in Example 1, Comparative Example 1, and Comparative Example 2 are used as the working electrode, Ag / AgCl is used as the reference electrode, and a carbon rod is used as the auxiliary electrode. Linear sweep voltammetry (LSV) tests are carried out in a 1 mol / L KOH electrolyte solution. In the test potential window of 0 to -0.9 V (corresponding to the reversible hydrogen electrode), hydrogen evolution performance tests are carried out, the scanning rate is 5 mV / s, and the current is converted into current density. The test results are as Figure 7 shown. The experimental data are compensated for iR. The hydrogen evolution activity is analyzed using the relationship between the current density and the overpotential. The larger the absolute value of the current density and the lower the overpotential, the better the catalytic reaction performance. Compared with the amorphous alloy strip precursor FeCoNiZrPt of Comparative Example 1, the etched sample of Example 1 exhibits a low overpotential. When driving a current density of 10 mA / cm 2 , the overpotential is about 23 mV. When driving a current density of 500 mA / cm 2 , the overpotential is about 126 mV, far exceeding the performance of commercial Pt / C electrocatalyst.

[0083] The oxygen evolution performance test provided in the embodiment of the present invention is the same as the above hydrogen evolution test method. The samples prepared in Example 1, Comparative Example 1, and Comparative Example 3 are used as the working electrode, and the test window is 0 to 0.6 V (corresponding to the reversible hydrogen electrode). The oxygen evolution activity is analyzed using the relationship between the current density and the overpotential. The larger the absolute value of the current density and the lower the overpotential, the better the oxygen evolution catalytic reaction performance. The test results are as Figure 8 shown. Compared with the alloy strip precursor FeCoNiPRu and the commercial RuO2 catalyst, the amorphous overall water splitting electrocatalyst, that is, the etched FeCoNiPRu, exhibits a low overpotential. The overpotential at a current density of 10 mA / cm 2 is about 257 mV, and the overpotential at a current density of 500 mA / cm 2 is about 295 mV.

[0084] (II) Overall water splitting performance test of amorphous overall water splitting electrocatalyst:

[0085] In the embodiment of the present invention, a Zahner Zennium electrochemical workstation is used and a two-electrode system is adopted: Two samples prepared according to Example 1 are respectively selected as the cathode and the anode; two samples prepared according to Comparative Example 1 are used as the cathode and the anode; at the same time, Comparative Example 2 is used as the cathode and Comparative Example 3 is used as the anode. Linear sweep voltammetry (LSV) tests are carried out in a 1 mol / L KOH electrolyte solution, the test potential window is 1.0 to 2.5 V, the scanning rate is 5 mV / s, and the current is converted into current density. The test results are as Figure 9As shown, in the overall water splitting reaction, the amorphous overall water splitting electrocatalyst, namely FeCoNiPRu after etching, exhibits a low voltage of 1.53 V at a current density of 10 mA / cm 2 , which is better than 1.87 V of the unetched alloy strip precursor FeCoNiPRu and 1.61 V of the two-electrode overall water splitting system composed of noble metal-like Pt / C||RuO2.

[0086] (III) Hydrogen evolution and oxygen evolution stability tests of the amorphous overall water splitting electrocatalyst:

[0087] Using a Zahner Zennium electrochemical workstation and the same three-electrode test system as in (I), in 1 mol / L KOH electrolyte, the hydrogen evolution and oxygen evolution stability tests of the amorphous overall water splitting electrocatalyst are carried out by cyclic voltammetry (CV) and chronoamperometry (I-t curve). After area conversion, the amorphous overall water splitting electrocatalyst is tested for the long-term hydrogen evolution stability test curve at a constant current density of 500 mA / cm 2 . The results are as Figure 10 shown. The hydrogen evolution operation of the amorphous electrode is stable, and the voltage remains almost unchanged within 1000 hours under the constant current test, with a very small decrease. The above shows the excellent hydrogen evolution stability of the electrolyzed water catalyst of the present invention.

[0088] The method for testing the long-term oxygen evolution stability is the same as the above hydrogen evolution test, with a constant current density of 10 mA / cm 2 , and the results are as Figure 11 shown. The hydrogen evolution operation of the amorphous electrode is stable, and the voltage remains almost unchanged within 500 hours under the constant current test, with a very small decrease. The above shows the excellent hydrogen evolution stability of the electrolyzed water catalyst of the present invention.

[0089] (IV) Overall water splitting stability test of the amorphous overall water splitting electrocatalyst:

[0090] Using a Zahner Zennium electrochemical workstation and the same two-electrode test system as in (II), in 1 mol / L KOH electrolyte, the overall water splitting stability test of the amorphous overall water splitting electrocatalyst is carried out; using chronopotentiometry (E-t curve), a current density of 500 mA / cm 2 is selected for a 500 h test, and the test results are as Figure 12 shown. The continuous and stable curve in the 500-hour E-t test reflects the excellent overall water splitting catalytic stability of the overall water splitting electrocatalyst of the present invention.

[0091] The hydrogen evolution (HER), oxygen evolution (OER), and overall water splitting performance of the amorphous overall water splitting catalysts prepared in Example 1 and Example 2 are shown in Table 1.

[0092] Table 1

[0093] Example HER performance OER performance Overall water splitting performance 1 23 mV 257 mV 1.53V 2 44 mV 273 mV 1.56V

[0094] It can be seen from the above embodiments that the highly active and highly stable amorphous electrocatalyst for overall water splitting prepared by the present invention has high activity for hydrogen evolution and oxygen evolution, and good stability; when used as the cathode and anode of an electrocatalytic overall water splitting electrolyzer, stable and efficient overall water splitting can be achieved in an alkaline electrolyte. The preparation method of this catalytic electrode can obtain high catalytic performance with less ruthenium, is simple and effective, has low cost, is expandable, has more active sites in the prepared amorphous structure, has regular morphology and stable structure, and excellent performance.

[0095] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A highly active and highly stable amorphous overall water splitting catalyst, characterized in that, It includes a substrate and a dealloyed layer wrapping the substrate; The substrate is an amorphous alloy, and the chemical composition of the amorphous alloy is Fe a Co b Ni c P d Ru e , where a, b, c, d, and e all represent atomic ratios, and 50 ≤ a ≤ 60, 8 ≤ b ≤ 13, 8 ≤ c ≤ 13, 17 ≤ d ≤ 22, 0 < e ≤ 3, and a + b + c + d + e = 100; The dealloyed layer is amorphous, and its constituent elements include Fe, Co, Ni, P, Ru, and O. Moreover, Ru in the dealloyed layer exists in the form of a composite of zero-valent ruthenium and ruthenium oxide; Based on the total atomic number of Fe, Co, Ni, P, and Ru being 100%, in the dealloyed layer, the Fe atomic content is 20% - 40%, the Co atomic content is 9% - 15%, the Ni atomic content is 9% - 15%, the P atomic content is 30% - 50%, and the Ru atomic content is 3% - 10%.

2. The highly active and highly stable amorphous water splitting catalyst according to claim 1, wherein The dealloyed layer contains medium-range order structure; The content of zero-valent ruthenium in the Ru element on the surface of the dealloyed layer is greater than the content of positively charged ruthenium oxide of ruthenium.

3. The highly active and highly stable amorphous water splitting catalyst according to claim 1, wherein The thickness of the dealloyed layer is 3 - 5 microns.

4. The highly active and highly stable amorphous water splitting catalyst according to claim 1, wherein The dealloyed layer is formed by electrochemically etching the amorphous alloy.

5. The highly active and highly stable amorphous water splitting catalyst according to claim 4, characterized in that, The specific process of the electrochemical etching includes: immersing the amorphous alloy into an etching solution for electrochemical etching treatment to form the dealloyed layer.

6. The highly active and highly stable amorphous overall water splitting catalyst according to claim 4 or 5, wherein The electrochemical etching adopts a three-electrode system, and the amorphous alloy serves as the working electrode.

7. The highly active and highly stable amorphous water splitting catalyst according to claim 5, characterized in that, The etching solution is an acid solution with a concentration of 1.5 - 2.5 mol / L; The etching solution includes at least one of hydrochloric acid, sulfuric acid, and aqua regia.

8. The highly active and highly stable amorphous water splitting catalyst according to claim 5, wherein The voltage of the electrochemical etching treatment adopts the voltage corresponding to the maximum etching current; The time of the electrochemical etching treatment does not exceed 200 s.

9. The preparation method of the highly active and highly stable amorphous overall water splitting catalyst according to any one of claims 1 to 8, characterized in that, Immerse the amorphous alloy into an etching solution for electrochemical etching treatment to form the dealloyed layer, thereby obtaining the highly active and highly stable amorphous water electrolysis catalyst.

10. Application of the highly active and highly stable amorphous water electrolysis catalyst according to any one of claims 1 - 8 in water electrolysis.

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