Integrated oxygen evolution reaction electrode and large-scale preparation method and preparation system thereof

Abstract

The invention provides an integrated oxygen evolution reaction electrode and a large-scale preparation method and a large-scale preparation system thereof. The large-scale preparation method comprises the following steps: providing a conductive substrate; the method comprises the following steps: placing a conductive substrate in a corrosive liquid in a circular flow state, introducing an oxygen-containing gas into the corrosive liquid, and carrying out spontaneous electrochemical corrosion, so that a layered double hydroxide layer is formed on the conductive substrate in situ. The efficient, uniform and controllable large-scale preparation of the high-performance integrated oxygen evolution reaction electrode is realized by virtue of a collaborative strategy of circular flow of the corrosive liquid and active supply of the oxygen-containing gas, mass transfer limitation and concentration gradient are eliminated by circular flow, and continuous and stable reaction driving force is provided for spontaneous electrochemical corrosion by the oxygen-containing gas. According to the collaborative strategy, the consistency of large-scale preparation of the electrode is guaranteed macroscopically, active components are regulated and controlled microcosmically, damage to a local high-pH growth interface caused by violent disturbance is avoided, and a foundation is laid for amplification to an industrial production scale.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemistry, and particularly relates to an integrated oxygen evolution reaction electrode and a large-scale preparation method and preparation system thereof. BACKGROUND

[0002] Water electrolysis to produce hydrogen is an important path to realize green energy transformation. The anode oxygen evolution reaction (OER) is a key bottleneck that determines the overall efficiency of water electrolysis due to its slow kinetics. Nickel-iron layered double hydroxide (NiFe-LDH) is considered to be one of the most excellent non-noble metal OER catalysts in alkaline medium.

[0003] Currently, the main methods for preparing NiFe-LDH catalysts are coprecipitation, hydrothermal method, electrodeposition method, etc. These methods usually prepare powder catalysts, which need to be combined with conductive substrates (such as nickel foam, carbon paper, etc.) through "coating-drying" steps to make working electrodes. However, this powder coated electrode generally has the problem of weak catalyst and substrate adhesion, which is easy to peel off during long-term electrolysis, resulting in a decrease in activity.

[0004] In order to solve this problem, researchers have developed a technology of growing NiFe-LDH catalyst layer on the conductive substrate in situ to form an integrated self-supporting electrode. Among them, W. Zhao et al. reported a method based on electrochemical corrosion (DOI: 10.1002 / aenm.202102372), the main content of which is as follows: iron substrate is immersed in a solution containing Ni 2+ , and dissolved oxygen is used as an oxidant to induce micro-electrochemical corrosion of the iron substrate. This process can generate a local high-pH region near the substrate surface, so that Ni 2+ and Fe 2+ / Fe 3+Co-precipitation, in-situ growth of NiFe-LDH catalytic layer. The small size (e.g. 0.5 cm x 0.5 cm) electrodes prepared by this method exhibit excellent catalytic activity and stability. However, the in-situ growth method based on electrochemical corrosion reported in the above-mentioned literature, although successful in small-scale laboratory preparation, has the following technical defects that are difficult to overcome in the face of large-scale production facing industrialization (e.g. preparation of electrodes with an area of hundreds of square centimeters or even larger): (1) insufficient and uncontrollable reaction driving force: this method relies heavily on oxygen naturally dissolved from the air into the solution as the reactant of the cathodic reaction. For large-scale reaction systems, the solution volume is extremely large, the specific surface area is extremely small, and the mass transfer rate of oxygen is much lower than the reaction consumption rate, resulting in a slow or even stagnant electrochemical corrosion process, which cannot prepare large-area electrodes. (2) Poor product uniformity: in a static immersion large-size reaction tank, ion concentration gradient and dissolved oxygen concentration gradient are difficult to avoid. The area close to the liquid surface has sufficient oxygen but may be depleted of ions, while the deep area has sufficient ions but lacks oxygen, which will cause serious non-uniformity in the growth rate, thickness and component (Ni / Fe ratio) of NiFe-LDH in different areas of the same large-area substrate, ultimately leading to low overall performance of the electrode. (3) Uncontrolled ratio of key components: the Ni / Fe atomic ratio of the catalyst is the most critical factor in determining its OER activity. In scaled production, as the substrate corrosion proceeds, the concentration of Fe ions in the solution is constantly accumulated, while the concentration of Ni ions is constantly consumed, and the ratio of the two will undergo dramatic dynamic changes. The existing technology lacks real-time monitoring and control means for this key parameter, making it impossible to maintain the optimal Ni / Fe ratio throughout the growth process, which seriously affects the performance and batch-to-batch consistency of the final product.

[0005] Therefore, developing a large-scale preparation method for the preparation of oxygen evolution reaction electrodes that is suitable for industrial production, efficient, uniform and controllable, to solve the problems of oxygen supply, mass transfer uniformity and key component ratio control in the process of large-scale preparation, is a technical bottleneck that needs to be broken through for industrial application. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide an integrated oxygen evolution reaction electrode and a large-scale preparation method and system thereof. The present application realizes efficient, uniform and controllable large-scale preparation of high-performance integrated oxygen evolution reaction electrodes by means of the synergistic strategy of the circulating flow of the corrosion solution and the active supply of oxygen-containing gas. Specifically, the circulating flow of the corrosion solution effectively eliminates the ion concentration gradient and mass transfer limitation existing in the traditional static system, ensuring the uniform corrosion effect of the corrosion solution components on the surface of the conductive substrate; the oxygen-containing gas provides a continuous, sufficient and controllable source of reactants, replacing the uncontrollable natural oxygen dissolution process, thereby providing a stable driving force for the uniform spontaneous electrochemical corrosion process; therefore, through the synergistic cooperation of active oxygenation and mild mass transfer, the problem of insufficient oxygen supply in large-scale reactions is solved, and the destruction of the electrode growth interface (i.e. local high pH environment) by severe disturbance is avoided, thereby ensuring the consistency of the large-scale preparation of the integrated oxygen evolution reaction electrode on a macroscopic scale and ensuring the high controllability and stability of the active components (such as Ni / Fe atomic ratio) on a microscopic scale. Finally, the prepared integrated oxygen evolution reaction electrode exhibits excellent catalytic activity, reaction stability and batch consistency in the oxygen evolution reaction, laying a solid foundation for its linear scaling from laboratory scale to industrial production scale.

[0007] To achieve the object of the present application, the following technical solutions are adopted:

[0008] In a first aspect, the present application provides a large-scale preparation method of an integrated oxygen evolution reaction electrode, which comprises the following steps:

[0009] A conductive substrate is provided.

[0010] The conductive substrate is placed in a corrosion solution in a circulating flow state, and an oxygen-containing gas is introduced into the corrosion solution at the same time, and spontaneous electrochemical corrosion is carried out, so that a layered double hydroxide layer is formed in situ on the conductive substrate.

[0011] The present application realizes efficient, uniform and controllable large-scale preparation of high-performance integrated oxygen evolution reaction electrodes by means of the synergistic strategy of the circulating flow of the corrosion solution and the active supply of the oxygen-containing gas. Specifically, the circulating flow of the corrosion solution effectively eliminates the ion concentration gradient and mass transfer limitation existing in the traditional static system, ensuring the uniform corrosion effect of the corrosion solution components on the surface of the conductive substrate; the oxygen-containing gas provides a continuous, sufficient and controllable oxygen source for the electrochemical corrosion, replacing the uncontrollable natural oxygen dissolution process, thereby providing a stable driving force for the uniform spontaneous electrochemical corrosion process; therefore, through the synergistic cooperation of active oxygenation and mild mass transfer, the problem of insufficient oxygen supply in large-scale reaction is solved, and the destruction of the electrode growth interface (i.e. local high pH environment) by severe disturbance is avoided, thereby ensuring the consistency of the large-scale preparation of the integrated oxygen evolution reaction electrode on the macroscopic level and ensuring the high controllability and stability of the active components (such as Ni / Fe atomic ratio) on the microscopic level. Finally, the prepared integrated oxygen evolution reaction electrode exhibits excellent catalytic activity, reaction stability and batch consistency in the oxygen evolution reaction, laying a solid foundation for its linear scaling from laboratory scale to industrial production scale.

[0012] It should be noted that "spontaneous electrochemical corrosion" refers to the corrosion primary cell reaction between the conductive substrate, the alloy formed at the initial stage of the reaction and the corrosion solution. The reaction driving force comes from the natural electrode potential difference existing between the conductive substrate and the alloy formed at the initial stage of the reaction, which spontaneously drives the flow of electrons and chemical reactions, i.e. electrochemical corrosion.

[0013] In the electrochemical corrosion process of the present application, a displacement reaction occurs first to form an alloy, and then a corrosion primary cell is formed due to the potential difference between the formed alloy and the metal element in the original conductive substrate, thereby spontaneously growing a layered double hydroxide layer.

[0014] Preferably, the conductive substrate is a conductive porous metal substrate.

[0015] Preferably, the conductive porous metal substrate includes any one or a combination of at least two of foamed iron, iron mesh, iron felt, foamed nickel, nickel mesh or nickel felt.

[0016] Preferably, the corrosion solution is a metal salt solution.

[0017] Preferably, the metal salt solution is a nickel salt solution or an iron salt solution. For example, the nickel salt solution can be a nickel chloride solution, and the iron salt solution can be an iron chloride solution.

[0018] Preferably, the concentration of the metal salt solution is 50-500 mmol / L, for example, it can be 50 mmol / L, 100 mmol / L, 200 mmol / L, 300 mmol / L, 400 mmol / L or 500 mmol / L, etc.

[0019] Preferably, a displacement reaction can spontaneously occur between the metal element in the conductive substrate and the metal ion in the etching solution. It should be noted that the metal element in the conductive substrate is different from the metal element in the etching solution. Preferably, when the conductive substrate is an iron-based material, the etching solution is a nickel salt solution, and the concentration is 50-200 mmol / L, for example, it can be 50 mmol / L, 100 mmol / L, 150 mmol / L or 200 mmol / L, etc.

[0020] Preferably, when the conductive substrate is a nickel-based material, the etching solution is an iron salt solution, and the concentration is 100-500 mmol / L, for example, it can be 100 mmol / L, 200 mmol / L, 300 mmol / L, 400 mmol / L or 500 mmol / L, etc.

[0021] Preferably, the etching solution flows in a laminar flow parallel to the surface of the conductive substrate.

[0022] In the present application, the etching solution is circulated in a laminar flow parallel to the surface of the conductive substrate, which is beneficial to form a uniform and stable liquid-solid interface diffusion layer, ensuring the uniform and dense growth of the layered double hydroxide layer on the surface of the conductive substrate, and avoiding local concentration fluctuations and uneven deposition caused by turbulent flow.

[0023] Preferably, the flow rate of the etching solution is 0.01-0.2 m / s, for example, it can be 0.01 m / s, 0.05 m / s, 0.1 m / s, 0.15 m / s or 0.2 m / s, etc.

[0024] In the present application, the appropriate flow rate of the etching solution is beneficial to ensure sufficient reactant transport rate while avoiding mechanical erosion and damage to the fragile structure of the in-situ grown layered double hydroxide layer caused by excessively high flow rate, achieving a balance between growth kinetics and structural integrity.

[0025] Preferably, in the oxygen-containing gas, the oxygen content is 20-100 vol%, for example, it can be 20 vol%, 40 vol%, 60 vol%, 80 vol% or 100 vol%, etc.

[0026] For example, the oxygen-containing gas can be air, etc.

[0027] Preferably, the flow rate of the oxygen-containing gas is 0.1-2 L / min, for example, it can be 0.1 L / min, 0.5 L / min, 1 L / min, 1.5 L / min or 2 L / min, etc.

[0028] Preferably, after the oxygen-containing gas is introduced into the etching solution, micro-bubbles are formed in the etching solution.

[0029] Preferably, the average diameter of the micro-bubbles is 50-500 μm, for example, it can be 50 μm, 100 μm, 200 μm, 300 μm, 400 μm or 500 μm, etc.

[0030] The present application introduces oxygen-containing gas into the etching solution at a specific flow rate to form micro-bubbles in the etching solution, so that the mass transfer rate of oxygen and the reaction consumption rate are balanced, thereby maintaining the concentration of dissolved oxygen in the etching solution stable and improving the efficiency of electrochemical etching, laying a foundation for the large-scale preparation of electrodes.

[0031] Preferably, the concentration of metal cations in the etching solution is monitored online during the electrochemical etching process, so that the concentration of metal cations in the etching solution is maintained within a predetermined range.

[0032] The present application ensures the sustained, stable and controllable growth of the layered double hydroxide layer by monitoring the concentration of metal cations in the etching solution in real time, thereby ensuring the high consistency and reproducibility of the performance of the batch-prepared electrodes.

[0033] Preferably, the metal cations include nickel ions and iron ions, and the predetermined molar concentration ratio of the nickel ions and the iron ions is (1.5-4):1, for example, it can be 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1 or 4:1, etc.

[0034] The present application dynamically controls the predetermined molar concentration ratio of nickel ions and iron ions in the etching solution to be (1.5-4):1, which is beneficial to the formation of nickel-iron hydroxide catalytic phase with more optimal electronic structure, and the layered double hydroxide layer thus exhibits more optimal intrinsic catalytic activity.

[0035] Preferably, during the spontaneous electrochemical etching process, the parameters include:

[0036] The reaction temperature is 25-40℃, for example, it can be 25℃, 30℃, 35℃ or 40℃, etc., and the reaction time is 6-96 h, for example, it can be 6 h, 12 h, 18 h, 24 h, 30 h, 36 h, 42 h, 48 h, 54 h, 60 h, 66 h, 72 h, 78 h, 84 h, 90 h or 96 h, etc.

[0037] Under the synergistic cooperation of the above-mentioned multiple suitable parameters, the growth kinetics of the layered double metal hydroxide layer can be accurately regulated, so that a catalytic layer with ideal thickness, excellent three-dimensional porous structure and high intrinsic activity is prepared in situ on the conductive substrate, and finally a high-performance and high-stability integrated oxygen evolution reaction electrode is obtained.

[0038] Preferably, the large-scale preparation method comprises the following steps:

[0039] (1) providing a conductive porous metal substrate, wherein the conductive porous metal substrate comprises any one or a combination of at least two of foamed iron, iron mesh, iron felt, foamed nickel, nickel mesh or nickel felt.

[0040] The conductive porous metal substrate is subjected to degreasing, pickling and water washing to obtain a pretreated conductive porous metal substrate.

[0041] (2) placing at least one (for example, 1, 2, 5 or 10, etc.) of the pretreated conductive porous metal substrate in a corrosion solution in a circulating flow state, and introducing an oxygen-containing gas into the corrosion solution to form micro-bubbles with an average diameter of 50-500 μm in the corrosion solution, so as to form a layered nickel-iron hydroxide layer in situ on the conductive porous metal substrate through spontaneous electrochemical corrosion.

[0042] In the process of the spontaneous electrochemical corrosion, the parameters include: the reaction temperature is 25-40℃, and the reaction time is 6-96h.

[0043] (3) after the spontaneous electrochemical corrosion is completed, the conductive porous metal substrate with the layered nickel-iron hydroxide layer formed in situ is taken out, and then is subjected to cleaning and drying to obtain an integrated oxygen evolution reaction electrode.

[0044] In the second aspect, the application provides an integrated oxygen evolution reaction electrode, which is prepared by using the large-scale preparation method according to the first aspect.

[0045] In a third aspect, the present application provides a preparation system for an integrated oxygen evolution reaction electrode, wherein the preparation method according to the first aspect is performed in the preparation system, and the preparation system comprises:

[0046] a reaction tank, wherein an electrode hanger for fixing a conductive substrate and a microporous gas diffuser for transmitting oxygen-containing gas are arranged in the reaction tank.

[0047] a circulating solution tank, wherein a circulating etching liquid inlet and a circulating etching liquid outlet are arranged in the circulating solution tank, the circulating etching liquid inlet is connected to the outlet of the reaction tank, and the circulating etching liquid outlet is connected to the inlet of the reaction tank.

[0048] Preferably, the number of conductive substrates fixed by the electrode hanger is at least one. For example, the number can be 1, 2, 3, or 4, and when the number is at least 2, the conductive substrates can be arranged in an array.

[0049] Preferably, a peristaltic pump is arranged between the inlet and the outlet of the reaction tank and the circulating etching liquid inlet and the circulating etching liquid outlet of the circulating solution tank, respectively.

[0050] Preferably, the preparation system further comprises:

[0051] a storage tank, wherein the storage tank is in communication with the circulating solution tank, and is used to deliver etching liquid to the circulating solution tank, so that the concentration of metal cations in the circulating etching liquid is maintained within a preset range.

[0052] Preferably, the preparation system further comprises:

[0053] a UV-Vis monitoring system, wherein the UV-Vis monitoring system is used to monitor the concentration of metal cations in the circulating etching liquid in the circulating solution tank, and feed back the monitoring result to the storage tank, so that the concentration of metal cations in the circulating etching liquid is maintained within a preset range.

[0054] The numerical ranges described in the present application include not only the point values listed above, but also any point values between the above-mentioned numerical ranges that are not listed, and the present application does not exhaustively list the specific point values included in the ranges for the sake of brevity and simplicity.

[0055] Compared with the prior art, the present application has the following beneficial effects:

[0056] (1) The present application realizes the efficient, uniform and controllable large-scale preparation of high-performance integrated oxygen evolution reaction electrode by means of the synergistic strategy of the circulating flow of the corrosion solution and the active supply of oxygen-containing gas. Specifically, the circulating flow of the corrosion solution effectively eliminates the ion concentration gradient and mass transfer limitation existing in the traditional static system, ensuring the uniform corrosion effect of the corrosion solution components on the surface of the conductive substrate; the oxygen-containing gas provides a continuous, sufficient and controllable oxygen source, replacing the uncontrollable natural oxygen dissolution process, thereby providing a stable driving force for the uniform spontaneous electrochemical corrosion process; therefore, through the synergistic cooperation of active oxygenation and mild mass transfer, the problem of insufficient oxygen supply in large-scale reaction is solved, and the destruction of the electrode growth interface (i.e. local high pH environment) by severe disturbance is avoided, the production efficiency is improved, thereby ensuring the consistency of the large-scale preparation of the integrated oxygen evolution reaction electrode on the macroscopic level, and ensuring the uniformity of the thickness and composition of the layered nickel-iron hydroxide layer on the microscopic level.

[0057] (2) The integrated oxygen evolution reaction electrode prepared by the present application exhibits excellent OER catalytic activity in the oxygen evolution reaction, and at the same time, due to the firm combination of the catalytic layer (i.e. the layered nickel-iron hydroxide layer) with the conductive substrate and the uniform composition, the electrode exhibits a lower activity decay rate in long-term stability test, and exhibits excellent reaction stability and batch consistency.

[0058] (3) The present application provides a complete, feasible and repeatable industrial production scheme, which lays a foundation for the commercial application of high-performance integrated oxygen evolution reaction electrode. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 The figure is a schematic diagram of the preparation system of the integrated oxygen evolution reaction electrode provided by the present application in one embodiment.

[0060] Figure 2 The figure is a surface SEM image of the integrated oxygen evolution reaction electrode provided by the present application in Example 1 under 1000 times magnification.

[0061] Figure 3 The figure is a surface SEM image of the integrated oxygen evolution reaction electrode provided by the present application in Example 1 under 10000 times magnification.

[0062] Figure 4 The figure is a curve graph of the oxygen evolution catalytic performance of a plurality of batches of products prepared by the large-scale preparation method provided by the present application.

[0063] Among them, 1-reaction tank; 2-electrode hanger; 3-ceramic microporous aeration head; 4-circulating solution tank; 5-liquid storage tank; 6-UV-Vis monitoring system; 7-peristaltic pump. DETAILED DESCRIPTION

[0064] The technical solutions of the present application will be further illustrated by specific embodiments. It should be understood by those skilled in the art that the embodiments are only used to understand the present application, and should not be regarded as specific limitations of the present application.

[0065] It should be understood that, in the description of the present application, the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can be explicitly or implicitly included one or more. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0066] It should be noted that, in the description of the present application, unless otherwise specified and limited, the terms "provided", "connected", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0067] In one embodiment, the present application provides a preparation system of an integrated oxygen evolution reaction electrode as shown in Figure 1 The preparation system comprises:

[0068] A reaction tank 1, wherein an electrode hanger 2 for fixing a conductive substrate and a plurality of ceramic microporous aeration heads 3 for transmitting oxygen-containing gas are arranged in the reaction tank 1, and the ceramic microporous aeration heads 3 are located at the bottom of the reaction tank 1.

[0069] A circulating solution tank 4, which comprises a circulating etching liquid inlet connected with the outlet of the reaction tank 1 and a circulating etching liquid outlet connected with the inlet of the reaction tank 1.

[0070] A liquid storage tank 5, which is in communication with the circulating solution tank 4 and is used to deliver etching liquid to the circulating solution tank 4, so that the concentration of metal cations in the circulating etching liquid is maintained within a predetermined range.

[0071] A UV-Vis monitoring system 6 is arranged to monitor the concentration of metal cations in the circulating corrosion solution in the circulating solution tank 4 and feed back the monitoring result to the storage tank 5, so that the concentration of metal cations in the circulating corrosion solution is maintained within a preset range.

[0072] The inlet and outlet of the reaction tank 1 are respectively connected with the circulating corrosion solution inlet and outlet of the circulating solution tank 4 through peristaltic pumps 7.

[0073] In another specific embodiment, based on the above preparation system, a preparation method of an integrated oxygen evolution reaction electrode is provided.

[0074] Embodiment 1

[0075] The embodiment provides a large-scale preparation method of an integrated oxygen evolution reaction electrode, which comprises the following steps:

[0076] (1) providing a conductive porous metal substrate, which is a foam iron (100 PPI) with a size of 50 cm x 50 cm.

[0077] The conductive porous metal substrate is deoiled in acetone for 15 min, then pickled in 1 mol / L hydrochloric acid for 10 min, and finally washed with deionized water to neutralization to obtain a pretreated conductive porous metal substrate.

[0078] (2) fixing 6 pretreated conductive porous metal substrates on the electrode hanger of the reaction tank in an array, and placing them in a circulating corrosion solution, and at the same time, introducing pure oxygen (oxygen content is 99.9 vol%) into the corrosion solution through a ceramic microporous aeration head to form microbubbles with an average diameter of 50 μm in the corrosion solution, and performing spontaneous electrochemical corrosion to form a layered nickel-iron hydroxide layer in situ on the conductive porous metal substrate.

[0079] The corrosion solution is a nickel chloride solution with a concentration of 100 mmol / L; the corrosion solution flows in a laminar flow parallel to the surface of the conductive porous metal substrate, and the flow rate of the corrosion solution is 0.05 m / s; the flow rate of the pure oxygen is 0.1 L / min; during the electrochemical corrosion, the molar concentrations of nickel ions and iron ions in the corrosion solution are monitored online every 10 min, so that the molar concentration ratio of nickel ions to iron ions in the corrosion solution is maintained at 3:1; during the spontaneous electrochemical corrosion, the parameters include a reaction temperature of 30℃ and a reaction time of 48 h.

[0080] (3) After the electrochemical corrosion is completed, the conductive porous metal substrate on which the layered nickel-iron hydroxide layer is formed in situ is taken out, and then repeatedly cleaned with deionized water, and then dried in an oven at 70 DEG C for 4h to obtain an integrated oxygen evolution reaction electrode.

[0081] Figure 2 and Figure 3 respectively show the surface SEM images of the integrated oxygen evolution reaction electrode provided by the embodiment under 1000 times magnification and 10000 times magnification.

[0082] Through the scale preparation method provided by the embodiment, the preparation of the integrated oxygen evolution reaction electrode of batch 1, batch 2, batch 3 and batch 4 is carried out, and the oxygen evolution catalytic performance of the corresponding batch product is detected, as shown in Figure 4 As can be seen from the figure, the integrated oxygen evolution reaction electrode prepared by the scale preparation method provided by the application has good product consistency, and the overpotential error is within 3mV.

[0083] Example 2

[0084] The embodiment provides a scale preparation method of an integrated oxygen evolution reaction electrode, and the scale preparation method comprises the following steps:

[0085] (1) A conductive porous metal substrate is provided, and the conductive porous metal substrate is a foamed iron (100 PPI) with a size of 50cm*50cm.

[0086] The conductive porous metal substrate is degreased in acetone for 15min, and then soaked in 1mol / L hydrochloric acid for 10min for pickling, and finally washed with deionized water to neutral to obtain a pretreated conductive porous metal substrate.

[0087] (2) Six pretreated conductive porous metal substrates are fixed on the electrode hanger of the reaction tank in an array arrangement, and are placed in a circulating flow state corrosion liquid, and at the same time, pure oxygen (oxygen content is 99.9vol%) is introduced into the corrosion liquid through a ceramic microporous aeration head to form micro-bubbles with an average diameter of 300μm in the corrosion liquid, and spontaneous electrochemical corrosion is carried out to form a layered nickel-iron hydroxide layer on the conductive porous metal substrate in situ.

[0088] The corrosion liquid is a nickel chloride solution with a concentration of 300 mmol / L; the corrosion liquid flows in a laminar flow parallel to the surface of the conductive porous metal substrate at a flow rate of 0.1 m / s; the flow rate of the pure oxygen is 1 L / min; during the electrochemical corrosion, the molar concentrations of nickel ions and iron ions in the corrosion liquid are monitored online every 10 min, so that the molar concentration ratio of nickel ions to iron ions in the corrosion liquid is maintained at 2:1; during the spontaneous electrochemical corrosion, the parameters include: the reaction temperature is 25°C, and the reaction time is 96 h.

[0089] (3) After the electrochemical corrosion is completed, the conductive porous metal substrate on which the layered nickel-iron hydroxide layer is formed in situ is taken out, then repeatedly cleaned with deionized water, and then dried in an oven at 70°C for 4 h to obtain an integrated oxygen evolution reaction electrode.

[0090] Example 3

[0091] The embodiment provides a large-scale preparation method of an integrated oxygen evolution reaction electrode, and the large-scale preparation method comprises the following steps:

[0092] (1) A conductive porous metal substrate is provided, and the conductive porous metal substrate is a foam iron (100 PPI) with a size of 50 cm*50 cm.

[0093] The conductive porous metal substrate is subjected to oil removal in acetone for 15 min, then is subjected to acid pickling in 1 mol / L hydrochloric acid for 10 min, and finally is washed with deionized water until neutral to obtain a pretreated conductive porous metal substrate.

[0094] (2) Six pretreated conductive porous metal substrates are fixed on an electrode hanger of a reaction tank in an array arrangement, and are placed in a corrosion liquid in a circulating flow state, and air (oxygen content is 21 vol%) is introduced into the corrosion liquid through a ceramic microporous aeration head to form microbubbles with an average diameter of 500 μm in the corrosion liquid, so that spontaneous electrochemical corrosion is performed to form a layered nickel-iron hydroxide layer on the conductive porous metal substrate in situ.

[0095] The corrosion liquid is a nickel chloride solution with a concentration of 300 mmol / L; the corrosion liquid flows in a laminar flow parallel to the surface of the conductive porous metal substrate at a flow rate of 0.1 m / s; the flow rate of the pure oxygen is 1 L / min; during the electrochemical corrosion, the molar concentrations of nickel ions and iron ions in the corrosion liquid are monitored online every 10 min, so that the molar concentration ratio of nickel ions to iron ions in the corrosion liquid is maintained at 2:1; during the spontaneous electrochemical corrosion, the parameters include: the reaction temperature is 25°C, and the reaction time is 96 h.

[0096] (3) After the electrochemical corrosion is completed, the conductive porous metal substrate on which the layered nickel-iron hydroxide layer is formed in situ is taken out, and then repeatedly cleaned with deionized water, and then dried in an oven at 70°C for 4h to obtain an integrated oxygen evolution reaction electrode.

[0097] Example 4

[0098] The difference between this example and Example 1 is that the flow rate of the corrosion solution is 0.005 m / s.

[0099] The remaining large-scale preparation methods and parameters remain the same as in Example 1.

[0100] Example 5

[0101] The difference between this example and Example 1 is that the flow rate of the corrosion solution is 0.5 m / s.

[0102] The remaining large-scale preparation methods and parameters remain the same as in Example 1.

[0103] Example 6

[0104] The difference between this example and Example 1 is that the average diameter of the microbubbles is 10 μm.

[0105] The remaining large-scale preparation methods and parameters remain the same as in Example 1.

[0106] Example 7

[0107] The difference between this example and Example 1 is that the average diameter of the microbubbles is 1000 μm.

[0108] The remaining large-scale preparation methods and parameters remain the same as in Example 1.

[0109] Comparative Example 1

[0110] The difference between this comparative example and Example 1 is that the flow rate of the corrosion solution is 0, i.e. the corrosion solution is in a static state.

[0111] The remaining large-scale preparation methods and parameters remain the same as in Example 1.

[0112] Comparative Example 2

[0113] The difference between this comparative example and Example 1 is that no pure oxygen is introduced and no microbubbles are generated.

[0114] The remaining large-scale preparation methods and parameters remain the same as in Example 1.

[0115] Performance Test

[0116] The integrated oxygen evolution reaction electrode provided in the above examples and comparative examples was used as a working electrode, a carbon rod was used as a counter electrode, Hg / HgO was used as a reference electrode, 1 mol / L of KOH was used as a reaction medium, the test temperature was 25°C, and the prepared integrated oxygen evolution reaction electrode was tested for the required oxygen evolution overpotential when reaching a current density of 10 mA / cm 2 and the average value was taken.

[0117] The test results are shown in Table 1.

[0118] Table 1

[0119]

[0120] Analysis:

[0121] As shown in Table 1, the present application realizes efficient, uniform and controllable large-scale preparation of high-performance integrated oxygen evolution reaction electrodes by means of the synergistic strategy of the circulating flow of the corrosion solution and the active supply of oxygen-containing gas. Specifically, the circulating flow of the corrosion solution effectively eliminates the ion concentration gradient and mass transfer limitation existing in the traditional static system, ensuring the uniform corrosion effect of the corrosion solution components on the surface of the conductive substrate; the oxygen-containing gas provides a continuous, sufficient and controllable oxygen source, replacing the uncontrollable natural oxygen dissolution process, thereby providing a stable driving force for the uniform spontaneous electrochemical corrosion process; therefore, through the synergistic cooperation of active oxygenation and mild mass transfer, the problem of insufficient oxygen supply in large-scale reaction is solved, and the destruction of the electrode growth interface (i.e. local high pH environment) by severe disturbance is avoided, the production efficiency is improved, thereby ensuring the consistency of the large-scale preparation of the integrated oxygen evolution reaction electrode on the macroscopic level and ensuring the uniformity of the thickness and composition of the layered nickel-iron hydroxide layer on the microscopic level. The prepared integrated oxygen evolution reaction electrode exhibits excellent OER catalytic activity in the oxygen evolution reaction, and since the catalytic layer (i.e. the layered nickel-iron hydroxide layer) is firmly combined with the conductive substrate and has uniform composition, the electrode exhibits a lower activity decay rate in long-term stability testing, showing excellent reaction stability and batch consistency.

[0122] As shown in the comparison of Example 1 and Examples 4-5, if the flow rate of the corrosion solution is too low, the nickel-iron ratio of the generated layered nickel-iron hydroxide deviates from the optimal value due to insufficient solution mass transfer, causing the intrinsic activity to decrease; if the flow rate of the corrosion solution is too high, the high pH microenvironment on the surface of the electrode is destroyed by the rapidly flowing solution, inhibiting the deposition of the layered nickel-iron hydroxide, resulting in a decrease in electrode performance.

[0123] It can be seen from the comparison of Example 1 with Examples 6-7 that if the average diameter of the micro-bubbles is too small, the bubbles are easily attached to the electrode surface, hindering the deposition of the layered nickel-iron hydroxide, resulting in a decrease in the electrode performance; if the average diameter of the micro-bubbles is too large, the bubbles will generate strong turbulent flow and stirring effect during the rising process, destroying the micro-environment of the electrode surface, inhibiting the deposition of the layered nickel-iron hydroxide, resulting in a decrease in the electrode performance.

[0124] It can be seen from the comparison of Example 1 with Comparative Example 1 that if the corrosion solution is in a static state, due to the slow mass transfer of the solution, the nickel-iron ratio of the generated layered nickel-iron hydroxide greatly deviates from the optimal value, resulting in a decrease in the intrinsic activity.

[0125] It can be seen from the comparison of Example 1 with Comparative Example 2 that if the pure oxygen is not introduced and the micro-bubbles are not generated, due to the gradual consumption of the dissolved oxygen during the reaction process and the inability to obtain effective supplement, the further progress of the electrochemical corrosion reaction is inhibited, resulting in a significant decrease in the catalyst loading of the electrode and a decrease in the performance.

[0126] It should be noted that the process method of the present application is illustrated by the above examples, but the present application is not limited to the above process steps, i.e. it does not mean that the present application must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement on the present application, equivalent replacement of the selected materials of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for large-scale preparation of an integrated oxygen evolution reaction electrode, characterized in that, The large-scale preparation method includes the following steps: Provide a conductive substrate; The conductive substrate is placed in a circulating corrosive solution, and oxygen-containing gas is introduced into the corrosive solution to carry out spontaneous electrochemical corrosion, so that a layered bimetallic hydroxide layer is formed in situ on the conductive substrate.

2. The method for large-scale preparation according to claim 1, characterized in that, The conductive substrate is a conductive porous metal substrate; Preferably, the corrosive solution is a metal salt solution; Preferably, the concentration of the metal salt solution is 50-500 mmol / L; Preferably, the elemental metal in the conductive substrate and the metal ions in the etching solution can spontaneously undergo a displacement reaction.

3. The method for large-scale preparation according to claim 2, characterized in that, The corrosive liquid circulates parallel to the surface of the conductive substrate in a laminar flow manner. Preferably, the flow rate of the corrosive liquid is 0.01-0.2 m / s.

4. The method for large-scale preparation according to any one of claims 1-3, characterized in that, The oxygen-containing gas has an oxygen content of 20-100 vol%. Preferably, the flow rate of the oxygen-containing gas is 0.1-2 L / min; Preferably, after the oxygen-containing gas is introduced into the corrosive liquid, microbubbles are formed in the corrosive liquid; Preferably, the average diameter of the microbubbles is 50-500 μm.

5. The method for large-scale preparation according to any one of claims 1-4, characterized in that, During the electrochemical corrosion process, the concentration of metal cations in the corrosion solution is monitored online to maintain the concentration of metal cations in the corrosion solution within a preset range. Preferably, the metal cation includes nickel ions and iron ions, and the preset molar concentration ratio of nickel ions and iron ions is (1.5-4):

1.

6. The method for large-scale preparation according to any one of claims 1-5, characterized in that, During the spontaneous electrochemical corrosion process, the parameters include: reaction temperature of 25-40℃ and reaction time of 6-96h.

7. The method for large-scale preparation according to any one of claims 1-6, characterized in that, The large-scale preparation method includes the following steps: (1) Provide a conductive porous metal substrate, wherein the conductive porous metal substrate comprises any one or a combination of at least two of foamed iron, iron mesh, iron felt, foamed nickel, nickel mesh or nickel felt; The conductive porous metal substrate is subjected to degreasing, acid washing and water washing to obtain a pretreated conductive porous metal substrate; (2) Place at least one of the pretreated conductive porous metal substrates in a circulating corrosion solution, and simultaneously introduce oxygen-containing gas into the corrosion solution to form microbubbles with an average diameter of 50-500 μm in the corrosion solution for spontaneous electrochemical corrosion, so that a layered nickel-iron hydroxide layer is formed in situ on the conductive porous metal substrate. The etching solution is a nickel or iron salt solution with a concentration of 50-500 mmol / L. The elemental metal in the conductive porous metal substrate and the metal ions in the etching solution can spontaneously undergo a displacement reaction. The etching solution circulates parallel to the surface of the conductive porous metal substrate in a laminar flow manner, with a flow rate of 0.01-0.2 m / s. The oxygen-containing gas has an oxygen content of 20-100 vol% and a flow rate of 0.1-2 L / min. During the electrochemical etching process, the molar concentrations of nickel and iron ions in the etching solution are monitored online to maintain the molar ratio of nickel to iron ions in the etching solution within the range of (1.5-4):

1. The parameters for the spontaneous electrochemical etching process include: a reaction temperature of 25-40℃ and a reaction time of 6-96 h. (3) After the spontaneous electrochemical corrosion is completed, the conductive porous metal substrate in which the in-situ layered nickel-iron hydroxide layer is formed is removed, and then cleaned and dried to obtain an integrated oxygen evolution reaction electrode.

8. An integrated oxygen evolution reaction electrode, characterized in that, The integrated oxygen evolution reaction electrode is prepared using the large-scale preparation method described in any one of claims 1-7.

9. A system for preparing an integrated oxygen evolution reaction electrode, characterized in that, The preparation method according to any one of claims 1-7 is carried out in the preparation system, the preparation system comprising: The reaction tank is equipped with an electrode holder for fixing a conductive substrate and a microporous gas diffuser for transporting oxygen-containing gas. A circulating solution tank includes a circulating corrosion liquid inlet and a circulating corrosion liquid outlet. The circulating corrosion liquid inlet is connected to the outlet of the reaction tank, and the circulating corrosion liquid outlet is connected to the inlet of the reaction tank.

10. The preparation system according to claim 9, characterized in that, The number of conductive substrates fixed by the electrode bracket is at least one; Preferably, a peristaltic pump is provided between the inlet and outlet of the reaction tank and the inlet and outlet of the circulating corrosion liquid of the circulating solution tank, respectively. Preferably, the preparation system further includes: A storage tank, which is connected to the circulating solution tank, is used to supply corrosive liquid to the circulating solution tank so that the concentration of metal cations in the circulating corrosive liquid is maintained within a preset range. Preferably, the preparation system further includes: The UV-Vis monitoring system is used to monitor the concentration of metal cations in the circulating corrosion solution in the circulating solution tank and feeds the monitoring results back to the storage tank, so that the concentration of metal cations in the circulating corrosion solution is maintained within a preset range.

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