Hydrogen production alloy with multi-scale electrochemical micro-couple structure and preparation method of hydrogen production alloy

Abstract

The invention provides a hydrogen production alloy with a multi-scale electrochemical micro-couple structure and a preparation method of the hydrogen production alloy. The hydrogen production alloy comprises an aluminum matrix, a nano-scale cathode phase and a micron-scale cathode network, the nanoscale cathode phase is an intermetallic compound distributed in the aluminum matrix; the micron-sized cathode network is Ga-In-Sn eutectic alloy which is continuously distributed along the grain boundary of the aluminum matrix; the aluminum matrix is an anode phase; and the aluminum matrix, the nanoscale cathode phase and the micron-sized cathode network form a multi-scale micro couple structure. Through the synergistic effect of a nanoscale cathode phase and a micron-sized cathode network, nanoscale active sites are responsible for rapid'ignition 'and reaction starting, a micron-sized continuous network serves as a'main road' and is responsible for maintaining the depth and breadth of the reaction, and through the synergistic effect of the multi-scale micro-couple structure, the utilization rate of an aluminum matrix serving as an anode is remarkably increased; the theoretical value of complete reaction of aluminum is approached.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy materials, and particularly relates to a hydrogen production alloy with a multi-scale electrochemical microcell structure and a preparation method thereof. BACKGROUND

[0002] The aluminum-water reaction has important potential in the field of hydrogen energy and energy storage because 1 gram of aluminum can produce about 1240 milliliters of hydrogen gas. The essence of the reaction is that aluminum reacts with water to form aluminum hydroxide and release hydrogen gas, and the reaction has the advantages of high energy density, large raw material reserves, clean reaction process, etc., and becomes one of the key technical paths for portable power supply, emergency hydrogen supply and distributed energy systems. However, a dense and protective aluminum oxide (Al2O3) film is spontaneously formed on the surface of aluminum in the air, which greatly hinders the contact between aluminum and water, causes the reaction to start difficultly, and the actual hydrogen production efficiency is much lower than the theoretical value, which seriously restricts its practical application.

[0003] Currently, alloying and mechanical activation are mainly used to destroy the oxide film and promote the continuous reaction of the aluminum-water reaction. Among them, low-melting-point metals such as gallium (Ga), indium (In), and tin (Sn) are introduced to form aluminum-based alloys, and the low-melting-point metals are distributed at the interface of aluminum particles, which destroys the structural integrity of the oxide film under the reaction conditions, thereby exposing the aluminum surface and continuously reacting with water. Mechanical ball milling, composite salt assisted, by introducing defects, reducing particle size, and increasing surface energy, to improve the reactivity of aluminum. These methods improve the kinetic performance of the aluminum-water reaction to some extent and shorten the induction time.

[0004] However, the existing aluminum-water reaction system still faces several key challenges. First, the catalytic phase introduced in the alloying process is often unevenly distributed in the aluminum matrix, which is easy to migrate, segregate and even lose during the reaction process, resulting in a decrease in catalytic activity and insufficient cycle stability. Second, although mechanical activation can effectively destroy the surface oxide layer, the activated aluminum powder is easily re-passivated in the air, has poor storage stability, and has unsatisfactory repeated use performance. Therefore, in order to solve the problems of slow start, low rate, unstable storage, and insufficient cycle durability, the development of a new type of hydrogen production alloy has become the key to the development of the current aluminum-water hydrogen production technology. SUMMARY

[0005] The present application solves the technical problems of slow start, low rate, unstable storage, and insufficient cycle durability of the hydrogen production alloy.

[0006] To solve the above problems, the application provides a hydrogen production alloy with a multi-scale electrochemical microcell structure, which comprises an aluminum matrix, a nanoscale cathode phase and a micrometer-scale cathode network; the nanoscale cathode phase is an intermetallic compound distributed in the aluminum matrix; the micrometer-scale cathode network is a Ga-In-Sn eutectic alloy continuously distributed along the grain boundaries of the aluminum matrix; the aluminum matrix is an anode phase; and the aluminum matrix, the nanoscale cathode phase and the micrometer-scale cathode network form a multi-scale microcell structure.

[0007] The technical effects achieved by the technical scheme are as follows: the nanoscale cathode phase particles are dispersedly distributed in the aluminum matrix, the nanoscale cathode phase particles form high-density cathode active sites, the activation energy of the aluminum-water reaction is greatly reduced, a large number of initial reaction active sites are provided for water decomposition, the hydrogen production alloy can quickly establish an electrochemical reaction channel after being in contact with water, and the reaction induction time is significantly shortened to ≤15 seconds; a micrometer-scale continuous Ga-In-Sn eutectic alloy network is constructed at the grain boundaries of the aluminum matrix, a high-efficiency micrometer-scale cathode network is formed, the rapid transfer of electrons between the aluminum matrix and the Ga-In-Sn network is promoted, the continuous and efficient operation of the microcell is maintained, the Ga-In-Sn liquid alloy penetrates along the grain boundaries, continuously activates the aluminum matrix, and provides a continuous channel for the penetration of the reactant water and the shedding of the product aluminum hydroxide, thereby effectively preventing the formation and coverage of the dense passivation layer on the surface of the aluminum matrix. Therefore, through the synergistic effect of the nanoscale cathode phase and the micrometer-scale cathode network, the nanoscale active sites are responsible for rapid "ignition" and reaction start, and the micrometer-scale continuous network is responsible for maintaining the depth and breadth of the reaction. The synergistic effect of the multi-scale microcell structure significantly improves the utilization rate of the aluminum matrix as the anode, and the total hydrogen production amount can reach about 1.2 L·g -1 , which is close to the theoretical value of the complete reaction of aluminum. The hydrogen production alloy exhibits excellent stability in multiple start-stop cycles, and the hydrogen production performance attenuation rate is ≤5% after 100 start-stop tests, which demonstrates the superior durability and reusability of the hydrogen production alloy. The technical scheme provides a hydrogen production alloy with a multi-scale electrochemical microcell structure, which integrates rapid start, high stability, high hydrogen production rate, high total hydrogen production amount and excellent cycle stability Preferably, the intermetallic compound is one or more of Al3Ni and Al3(Ni,Co).

[0008] The technical effects reached by the technical scheme are as follows: because the elements of Ni and Co have excellent characteristics of hydrogen evolution reaction catalysts, have extremely low hydrogen evolution overpotential, and can greatly reduce the energy barrier of water decomposition reaction, the intermetallic compound nanoparticles not only form a high-potential difference microelectrode with the aluminum matrix, but also serve as a high-efficiency catalytic active center, providing a large number of and high-activity initial reaction sites for water decomposition, and the effect is much better than other intermetallic compounds. Moreover, the elements of Ni and Co are easily introduced into the aluminum matrix by a conventional melting, casting and heat treatment process, and the required Al3Ni or Al3(Ni,Co) nano phase is generated in situ, the preparation method is controllable in cost, the process is mature, and large-scale industrial production is easy to realize.

[0009] Preferably, the particle size of the intermetallic compound is 20 nm to 100 nm; and / or the area density of the intermetallic compound is ≥1×10 5 mm -2 .

[0010] The technical effects reached by the technical scheme are as follows: the particle size of the intermetallic compound is controlled at the nanometer level, and at the same time, the super-high area density is realized, which is equivalent to constructing hundreds of thousands or even millions of independent and efficient nanoscale microelectrodes per square millimeter of microscale. Such a huge number of active sites makes the water decomposition reaction not need to go through a long induction period to find and activate the reaction point. Almost at the moment of contact with water, the nanoelectrodes on the entire alloy surface are activated at the same time, thereby realizing the nearly instantaneous hydrogen production starting speed. Moreover, the super-high density of nanocathode points ensures that there is an efficient electrochemical corrosion channel near any micro area of the aluminum matrix, and the reaction simultaneously advances from numerous points, constantly tears and explodes the passivation layer that may be formed, so that the continuous and dense covering film cannot be formed.

[0011] Preferably, the width of the Ga-In-Sn eutectic alloy is 0.5 μm to 2.0 μm; and / or the penetration degree of the Ga-In-Sn eutectic alloy is ≥90%.

[0012] The technical effects reached by the technical scheme are as follows: by designing the width of the Ga-In-Sn eutectic alloy to be 0.5-2.0 microns, the low-resistance and rapid penetration of the liquid metal is ensured, and the highest specific surface area and the densest distribution of the activated network are realized. When the width is too narrow, the surface tension effect of the liquid metal will become significant, the flow resistance will increase, and even the flow may be interrupted during preparation or reaction, which will affect the transmission depth and speed of the activation effect. Meanwhile, the continuity of the network cannot be ensured when the width is too narrow. When the width is too wide, on the one hand, the expensive Ga-In-Sn alloy will be wasted, and the material cost will be increased. On the other hand, the wide liquid metal phase will significantly reduce the overall mechanical strength and structural stability of the material, and the material is prone to breakage or deformation during use. More importantly, under the same amount of Ga-In-Sn eutectic alloy, the wider the channel, the sparser the network distribution, which will reduce the activated interface area in a unit volume, and is not conducive to achieving the fastest reaction rate. When the Ga-In-Sn eutectic alloy has a penetration degree of 90%, the low-melting-point Ga-In-Sn alloy forms a three-dimensional network structure that is interconnected from the surface to the interior. When the reaction starts, the Ga-In-Sn alloy on the surface melts first, penetrates and destroys the grain boundaries and oxide film of the aluminum like a “highway”, ensures that the reaction front can continuously advance to the interior of the aluminum matrix, prevents the reaction from being interrupted due to surface passivation, and thus maintains a stable and high hydrogen production rate. By controlling the continuity of the network, the corrosion depth and mode can be adjusted, and the reaction can be prevented from being too violent or too slow.

[0013] Preferably, the Ga-In-Sn eutectic alloy further comprises one or more of Bi and Zn.

[0014] The technical effects reached by the technical scheme are as follows: the addition of Bi can form a four or five eutectic system with Ga-In-Sn, which has a lower melting point. The lower the melting point, the less time and energy are required to convert from a solid state to a liquid state with activation ability, so that the start-up speed of hydrogen production is faster. When the micron-level continuous network is used as the “main road”, the liquid alloy containing Bi can more easily open the barrier of the aluminum grain when penetrating along the grain boundary of the aluminum, so that the deepest layer of aluminum can also be fully utilized, and the actual utilization rate of aluminum is closer to the theoretical value of complete aluminum reaction. The introduction of Zn can be used as a reaction rate regulator, and by adjusting the content of Zn, the intensity of the hydrogen production reaction can be finely adjusted.

[0015] Preferably, the atomic ratio of Co and Ni in the intermetallic compound is 0-0.5.

[0016] The technical effects reached by the technical scheme are as follows: the potential difference of the pure Al3Ni aluminum matrix is fixed, and by forming the Al3(Ni, Co) solid solution, a continuous adjustable potential knob is introduced, the Co atoms partially replace the Ni atoms, the Fermi level of the intermetallic compound and the stability of the surface in water are changed, the corrosion potential is finely adjusted, when the proportion of Ni is too high and the proportion of Co is close to 0, the potential difference is insufficient, the driving force of the aluminum anode dissolution may be insufficient, the reaction is slow to start and the rate is insufficient, and when the proportion of Co is too high, the potential difference is too large, the cathode reaction of the nano micro galvanic cell is too violent, a new passivation layer is formed, and the conversion rate and service life of aluminum are reduced.

[0017] Preferably, the mass ratio of Ga, In and Sn in the Ga-In-Sn eutectic alloy is 65-80:10-20:5-20.

[0018] The technical effects reached by the technical scheme are as follows: Ga is the main active ingredient, and the strong penetration and amalgamation ability need to be ensured, so the content of Ga needs to be ensured to be low enough, and excessive Ga will cause the alloy to be too thin and the surface tension to be too low, which may cause excessive penetration. In mainly functions to significantly reduce the melting point, and can improve the flowability and wettability of the alloy, so the content of In needs to be ensured to effectively improve the wettability and adjust the potential, and the cost of In is relatively high, and a high proportion will increase the cost. Sn has slightly high viscosity and structural strength, which can effectively prevent rapid loss due to water erosion during the reaction, so the content of Sn needs to be ensured to have a stabilizing and thickening effect, and a high Sn content will significantly increase the melting point of the eutectic alloy.

[0019] Preferably, in the Ga-In-Sn eutectic alloy, the content of Bi is ≤1at%, and the content of Zn is ≤1at%.

[0020] The technical effects reached by the technical scheme are as follows: the content of Bi is ≤1at%, and the content of Zn is ≤1at%, which ensures that Bi and Zn can be dissolved in the liquid Ga-In-Sn matrix in the form of atoms, without forming solid precipitates, and without affecting the low melting point and high flowability of the Ga-In-Sn eutectic alloy.

[0021] The application further provides a preparation method of the hydrogen production alloy with a multi-scale electrochemical micro galvanic structure, which can prepare the hydrogen production alloy of any of the technical schemes, and specifically includes the following steps: S10: mixing aluminum powder, element powder for forming an intermetallic compound and a grain refiner to obtain a mixed powder; S20: performing spark plasma sintering on the mixed powder to obtain an aluminum matrix with a grain boundary channel; S30: Under the protection of inert atmosphere, Ga-In-Sn eutectic alloy is pressed into the grain boundary channel of the aluminum matrix to obtain a hydrogen production alloy.

[0022] The technical effects achieved after the technical scheme are as follows: the preparation method of the hydrogen production alloy first prepares the aluminum matrix with the grain boundary channel through the spark plasma sintering, and then the Ga-In-Sn eutectic alloy is pressed into the grain boundary channel of the aluminum matrix. The spark plasma sintering can complete sintering in a very short time, effectively inhibits the growth of aluminum grains, and thus the aluminum matrix with fine grains and high-density grain boundaries is obtained, the aluminum matrix with the grain boundary channel is formed, and the in-situ generation and dispersion distribution of intermetallic compounds are realized. Under the protection of inert atmosphere, the liquid Ga-In-Sn eutectic alloy can be filled into the grain boundary channel of the aluminum matrix through pressing and infiltration. The preparation method combines the spark plasma sintering and the melt capillary infiltration process to prepare a new hydrogen production alloy, and the preparation method is simple and efficient.

[0023] Preferably, the temperature of the spark plasma sintering is 400-550 DEG C, the holding time of the spark plasma sintering is 2-10 min, and / or the pressure of the pressing and infiltration is 0.5-5 MPa, and the temperature of the pressing and infiltration is 80-140 DEG C.

[0024] The technical effects achieved after the technical scheme are as follows: the spark plasma sintering adopts a lower sintering temperature and a shorter holding time, effectively inhibits the growth of aluminum grains and the coarsening of intermetallic compounds, and thus the nanocrystalline aluminum matrix with high-density grain boundaries is successfully prepared. The temperature of 80-140 DEG C and the pressure of 0.5-5 MPa are sufficient to overcome the surface tension of the liquid metal, so that the liquid metal can be fully and completely infiltrated into the fine grain boundary channel of the aluminum matrix without damaging the skeleton structure of the matrix formed due to excessive pressure. Finally, a high-performance hydrogen production alloy with a complete structure and uniform distribution is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the accompanying drawings, in which: Figure 1 A structure schematic diagram of the hydrogen production alloy provided for the embodiment 1 of the present application; Figure 2 An SEM diagram of the hydrogen production alloy provided for the embodiment 1 of the present application; Figure 3 A comparison curve diagram of the hydrogen production performance of the hydrogen production alloy provided for the embodiment 1 of the present application and the hydrogen production alloy provided for the comparative example 1; Figure 4 A cycle stability test result diagram of the hydrogen production alloy provided for the embodiment 1 of the present application and the hydrogen production alloy provided for the comparative example 1. DETAILED DESCRIPTION

[0026] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0027] The present application provides a hydrogen production alloy with a multi-scale electrochemical micro-coupling structure, which comprises an aluminum matrix, a nano-scale cathode phase and a micro-scale cathode network; the nano-scale cathode phase is an intermetallic compound distributed in the aluminum matrix; the micro-scale cathode network is a continuous Ga-In-Sn eutectic alloy network distributed along the grain boundaries of the aluminum matrix; the aluminum matrix is an anode phase; and the aluminum matrix, the nano-scale cathode phase and the micro-scale cathode network form a multi-scale micro-coupling structure.

[0028] The embodiments of the present application provide a hydrogen production alloy with a multi-scale electrochemical micro-coupling structure. By dispersively distributing nano-scale cathode phase particles in the aluminum matrix, the nano-scale cathode phase particles form a high-density cathode active site, greatly reducing the activation energy of the aluminum-water reaction, providing a large number of initial reaction active sites for water decomposition, enabling the hydrogen production alloy to quickly establish an electrochemical reaction channel after contacting with water, and significantly shortening the reaction induction time to ≤15 seconds. By constructing a continuous Ga-In-Sn eutectic alloy network with a thickness of microns at the grain boundaries of the aluminum matrix, a high-efficiency micro-scale cathode network is formed, promoting the rapid transfer of electrons between the aluminum matrix and the Ga-In-Sn network, maintaining the continuous and efficient operation of the micro-coupling, and the Ga-In-Sn liquid alloy penetrates along the grain boundaries, continuously activates the aluminum matrix, and provides a continuous channel for the infiltration of reactant water and the shedding of product aluminum hydroxide, effectively preventing the formation and coverage of a dense passivation layer on the surface of the aluminum matrix. Therefore, through the synergistic effect of the nano-scale cathode phase and the micro-scale cathode network, the nano-scale active site is responsible for rapid "ignition" and reaction initiation, and the micro-scale continuous network is responsible for maintaining the depth and breadth of the reaction. The synergistic effect of this multi-scale micro-coupling structure significantly improves the utilization rate of the aluminum matrix as the anode, maintains the hydrogen production rate at ≥15~20 mL·min⁻¹·g⁻¹, and has a high and stable hydrogen production rate, with a total hydrogen production amount of about 1.2L·g -1 , close to the theoretical value of complete aluminum reaction, and the hydrogen production alloy exhibits excellent stability in multiple start-stop cycles, with a hydrogen production performance decay rate ≤5% after 100 start-stop tests, demonstrating its superior durability and reusability. The technical solution provides a multi-scale electrochemical micro-coupling structure hydrogen production alloy that integrates rapid start-up, high stability rate, high total hydrogen production amount and excellent cycle stability.

[0029] In the multi-size, nano-sized cathode phases and micro-sized cathode networks exist in the aluminum matrix in different size levels in the form of dots and networks, respectively, and work together and perform their respective functions.

[0030] In some embodiments of the present application, the intermetallic compound is one or more of Al3Ni, Al3(Ni,Co).

[0031] Since Ni and Co elements themselves have excellent hydrogen evolution reaction catalyst characteristics, with extremely low hydrogen evolution overpotential, which can greatly reduce the energy barrier of water decomposition reaction, the intermetallic compound nanoparticles not only form a high potential difference microcell with the aluminum matrix, but also serve as a highly efficient catalytic active center, providing a large number of and highly active initial reaction sites for water decomposition, which is much better than other intermetallic compounds. And Ni and Co elements as alloying elements are easily introduced into the aluminum matrix through conventional melting, casting and heat treatment processes, and in-situ generate the required Al3Ni or Al3(Ni,Co) nano-phase, the preparation method is cost controllable, the process is mature, and large-scale industrial production is easy to achieve. The intermetallic compound can also be Al5Co2. And the intermetallic compound also includes Mg, and appropriate amount of Mg can inhibit too fast corrosion, avoid instant alloy powdering or overheating reaction, thereby controlling the reaction rate and improving stability.

[0032] In some embodiments of the present application, the particle size of the intermetallic compound is 20 nm to 100 nm; and / or the areal density of the intermetallic compound is ≥1×10 5 mm -2， .

[0033] In the hydrogen production alloy, the particle size of the intermetallic compound is controlled at the nanometer level, while achieving an ultra-high areal density, which is equivalent to constructing hundreds of thousands or even millions of independent and efficient nanoscale microcells on a microscale of each square millimeter. Such a huge number of active sites makes the water decomposition reaction not need to go through a long induction period to find and activate the reaction sites. Almost at the moment of contact with water, the nanocells on the entire alloy surface are activated at the same time, thereby achieving a nearly instantaneous hydrogen production start-up speed. And the ultra-high density of the nanocathode points ensures that there are efficient electrochemical corrosion channels near any microzone of the aluminum matrix, and the reaction simultaneously advances from numerous points, constantly tearing and blasting the passivation layer that may be formed, so that it cannot form a continuous and dense covering film. Preferably, the areal density of the intermetallic compound is ≥2×10 5 mm -2 .

[0034] In some embodiments of the present application, the width of the Ga-In-Sn eutectic alloy is 0.5 μm to 2.0 μm; and / or the penetration degree of the Ga-In-Sn eutectic alloy is ≥90%.

[0035] In the hydrogen production alloy, by designing the width of the Ga-In-Sn eutectic alloy at 0.5 μm~2.0 μm, both low resistance and rapid penetration of the liquid metal are ensured, and the highest specific surface area and the densest distribution of the activation network are realized. When the width is too narrow, the surface tension effect of the liquid metal will become significant, the flow resistance will increase, and even the flow may be interrupted during preparation or reaction, affecting the transmission depth and speed of the activation effect. At the same time, it is difficult to ensure the continuity of the width. When the width is too wide, on the one hand, it will waste the expensive gallium-indium-tin alloy, increasing the material cost, and on the other hand, the wide liquid metal phase will significantly reduce the overall mechanical strength and structural stability of the material, which is easy to break or deform in use. More importantly, under the same amount of Ga-In-Sn eutectic alloy, wider channels mean sparser network distribution, which reduces the activation interface area per unit volume, and is not conducive to achieving the fastest reaction rate. When the Ga-In-Sn eutectic alloy has a penetration degree of ≥90%, the low-melting-point Ga-In-Sn alloy forms a three-dimensional network structure that is highly interconnected from the surface to the interior. When the reaction starts, water contacts the surface of the material, and the Ga-In-Sn alloy on the surface layer melts first, like a "highway", penetrating and destroying the grain boundaries and oxide film of aluminum, ensuring that the reaction front can continuously advance to the interior of the aluminum matrix, preventing the reaction from stopping due to surface passivation, thereby maintaining a stable and high hydrogen production rate. By controlling the continuity of the network, the depth and mode of corrosion can be adjusted to avoid excessive reaction or slow reaction. Preferably, the width of the Ga-In-Sn eutectic alloy is 0.7 μm~1.3 μm.

[0036] In some embodiments of the present application, the Ga-In-Sn eutectic alloy further comprises one or more of Bi, Zn.

[0037] Among them, the addition of Bi can form a lower-melting-point quaternary or quinary eutectic system with Ga-In-Sn. The lower the melting point, the less time and energy required to convert from solid to liquid state with activation ability, making the start-up speed of hydrogen production faster. When the micron-level continuous network is used as the "main road", the liquid alloy containing Bi penetrates along the grain boundaries of aluminum more easily, opening the barrier of aluminum grains, ensuring that the deepest layer of aluminum can be fully utilized, and the actual utilization rate of aluminum is closer to the theoretical value of complete reaction of aluminum. The introduction of Zn can be used as a reaction rate regulator, which can finely adjust the severity of the hydrogen production reaction by adjusting the content of Zn.

[0038] In some embodiments of the present application, the atomic ratio of Co and Ni in the intermetallic compound is 0~0.5.

[0039] Since the potential difference of pure Al3Ni aluminum matrix is fixed, and by forming Al3(Ni, Co) solid solution, a continuous adjustable potential knob is equivalent to being introduced, Co atoms partially replace Ni atoms, which can change the Fermi level of the intermetallic compound and the stability of its surface in water, thereby fine-tuning the corrosion potential, when the proportion of Ni is too high, Co is close to 0, the potential difference is insufficient, and the driving force of aluminum anodic dissolution may not be strong enough, resulting in slow reaction start and insufficient rate, when the proportion of Co is too high, the potential difference is too large, which can cause the cathodic reaction of the nano micro galvanic cell to be too violent, forming a new passivation layer and reducing the conversion rate and service life of aluminum.

[0040] In some embodiments of the present application, the mass ratio of Ga, In and Sn in the Ga-In-Sn eutectic alloy is 65-80: 10-20: 5-20.

[0041] In the formula, Ga is the main active ingredient, which needs to ensure strong penetration and amalgamation capacity, so the content of Ga needs to ensure that the melting point of the alloy is low enough, and excessive Ga is prevented, because excessive Ga can cause the alloy to be too thin and the surface tension to be too low, which can cause excessive penetration. In plays a major role in significantly reducing the melting point, while improving the flowability and wettability of the alloy, so the content of In needs to ensure that there is enough In to effectively improve the wettability and adjust the potential, and the cost of In is relatively high, and a high proportion of In will increase the cost. Sn has slightly higher viscosity and structural strength, which can effectively prevent rapid loss due to water erosion during the reaction process, so the content of Sn needs to ensure that it can play a stabilizing and thickening effect, and a high content of Sn will significantly increase the melting point of the eutectic alloy.

[0042] In some embodiments of the present application, the content of Bi in the Ga-In-Sn eutectic alloy is ≤1at%, and the content of Zn is ≤1at%.

[0043] In the formula, the content of Bi is ≤1at%, and the content of Zn is ≤1at%, which ensures that Bi and Zn can be dissolved in the liquid Ga-In-Sn matrix in atomic form, without forming solid precipitates, which will not affect the low melting point and high flowability of the Ga-In-Sn eutectic alloy.

[0044] The present application also provides a preparation method of a hydrogen-producing alloy with a multi-scale electrochemical micro galvanic structure, which can prepare the hydrogen-producing alloy of any of the above technical solutions, and specifically includes the following steps: S10: mixing aluminum powder, element powder for forming intermetallic compounds and grain refiner to obtain a mixed powder; S20: performing spark plasma sintering on the mixed powder to obtain an aluminum matrix with grain boundary channels; S30: under the protection of an inert atmosphere, pressing the Ga-In-Sn eutectic alloy into the grain boundary channels of the aluminum matrix to obtain a hydrogen-producing alloy.

[0045] In the preparation process of the hydrogen production alloy with a multi-scale electrochemical microgalvanic structure, an aluminum matrix with grain boundary channels is prepared by spark plasma sintering, and then a Ga-In-Sn eutectic alloy is pressed and infiltrated into the grain boundary channels of the aluminum matrix. The spark plasma sintering can complete sintering in a very short time, effectively inhibits the growth of aluminum grains, and thus an aluminum matrix with fine grains and high-density grain boundaries is obtained, forming an aluminum matrix with grain boundary channels. Meanwhile, the spark plasma sintering realizes in-situ generation and dispersion distribution of intermetallic compounds. Under the protection of an inert atmosphere, the liquid Ga-In-Sn eutectic alloy can be filled into the grain boundary channels of the aluminum matrix by pressing and infiltration. The preparation method combines spark plasma sintering and melt capillary infiltration process to prepare a new hydrogen production alloy, and the preparation method is simple and efficient.

[0046] In the application, the grain refiner is an alloy containing Ti and B, and the particle size of the grain refiner is 10-30 μm, preferably Al-Ti-B or TiB2.

[0047] In some embodiments of the application, in the preparation method of the hydrogen production alloy with a multi-scale electrochemical microgalvanic structure, the temperature of the spark plasma sintering is 400-550°C, the holding time of the spark plasma sintering is 2-10 min, and / or the pressure of the pressing and infiltration is 0.5-5 MPa, and the temperature of the pressing and infiltration is 80-140°C.

[0048] In the preparation process of the hydrogen production alloy with a multi-scale electrochemical microgalvanic structure, the spark plasma sintering adopts a lower sintering temperature and a shorter holding time, effectively inhibiting the growth of aluminum grains and the coarsening of intermetallic compounds, and thus a nanocrystalline aluminum matrix with high-density grain boundaries is successfully prepared. The temperature of 80-140°C and the pressure of 0.5-5 MPa are sufficient to overcome the surface tension of the liquid metal, so that the liquid metal can fully and completely infiltrate into the fine grain boundary channels of the aluminum matrix without damaging the skeleton structure of the matrix. Finally, a high-performance hydrogen production alloy with a complete structure and uniform distribution is obtained.

[0049] Example 1 S1: uniformly mixing Al, Ni, Co, Mg, and Al-Ti-B powders to obtain a mixed powder; S2: pre-pressing the mixed powder by cold isostatic pressing or unidirectional pressing at a pressure of 250 MPa for 3 min to obtain a powder compact; S3: spark plasma sintering the powder compact at a temperature of 500°C for 5 min to obtain an aluminum matrix with grain boundary channels; S4: under the protection of argon atmosphere ≥ 99.999%; liquid Ga-In-Sn eutectic alloy is pressurized into the grain boundary channel of the aluminum matrix at 100℃ and 2MPa, and cooled and solidified to form a hydrogen-producing alloy with a through grain boundary eutectic network.

[0050] In step S1, the mass component of Ni is 5%, the mass component of Co is 0.5%, the mass component of Mg is 1%, the mass component of Al-Ti-B is 0.2%, and the mass component of Al is 93.3%; in step S4, the mass component of Ga is 68.5%, the mass component of In is 21.5%, and the mass component of Sn is 10%.

[0051] The structural diagram of the hydrogen-producing alloy with a multi-scale electrochemical microcell structure obtained in Example 1 is shown in Figure 1 When the hydrogen-producing alloy is in contact with deionized water at 25℃, the intermetallic compounds distributed in the aluminum matrix and the adjacent aluminum form a microcell instantaneously. Due to the extremely high potential difference and number density, these nanocells can act like "detonators" to preferentially break through the corrosion front at the thinnest site of the aluminum surface oxide film, such as at dislocations and grain boundaries, resulting in an extremely short induction time, and the induction time for hydrogen production is only 8 seconds. The electrolyte penetrates through the holes caused by the nanocells and immediately contacts the micron-sized cathode network Ga-In-Sn eutectic alloy distributed along the grain boundaries, which forms a macroscopic cathode with the aluminum matrix. Due to its large surface area and excellent electrical conductivity, it catalyzes the water decomposition reaction to produce a large amount of hydrogen gas. At the same time, the micron-sized cathode network acts like "root systems" to continuously guide the corrosion reaction along the grain boundaries to the interior of the hydrogen-producing alloy, preventing surface passivation and thus maintaining a high and stable hydrogen production rate. Moreover, as the corrosion front advances into the interior, more internal intermetallic compounds are exposed and activated, further accelerating local corrosion. This positive feedback mechanism of "nanopitting initiation-micronetwork expansion-more nanopits activated" ensures that the reaction starts quickly and proceeds completely and uniformly until the aluminum matrix is fully consumed, ultimately achieving an aluminum conversion rate of more than 95%. The peak hydrogen production rate of the hydrogen-producing alloy in this embodiment reaches 19.2mL·min -1 ·g -1 ; the total hydrogen production amount is 1235mL·g -1 ; after 100 hydrogen production cycles, the hydrogen production amount can still reach 1180mL·g -1 , with a decay of only 4.5%. The hydrogen-producing alloy with a multi-scale electrochemical microcell structure solves the technical contradiction between high activity and high stability through the division and cooperation of cathodes of different sizes.

[0052] The SEM of the hydrogen-producing alloy with a multi-scale electrochemical microcell structure obtained in Example 1 is shown in Figure 2 Figure 2 ​The overall morphology of the hydrogen-producing alloy is shown, the average grain size is 10-30 μm, the aluminum matrix is a continuous phase of gray color, which constitutes the anode of the micro galvanic couple; the grain boundary clearly outlines the boundary of multiple grains; the micron-sized cathode network is distributed along the grain boundary, and the low-melting eutectic Ga-In-Sn alloy eutectic is shown in a sinuous network structure, which serves as an efficient cathode conductive channel in the electrolyte, guiding the corrosion reaction along the grain boundary. The intermetallic compound is a bright spot dispersed in the aluminum matrix, representing the intermetallic compound formed by Ni and Co elements, and the particle size of the intermetallic compound is 20-100 nm, which forms countless nanometer micro galvanic couples with the aluminum matrix. The irregular interface of the corrosion front extending from the Ga-In-Sn alloy eutectic network to the intracrystalline indicates that the reaction is advancing into the aluminum matrix, and the density of the nanometer cathode particles is higher near the interface, indicating that they are being activated and accelerating local corrosion.

[0053] Comparative Example 1 S1: uniformly mix Al, Ga, In, Sn, Zn, Cu, Al-Ti-B to obtain a mixed powder; S2: under the protection of an argon atmosphere with a purity of ≥99.999%, melt the mixed powder at 750°C, and rapidly cool the melt to obtain a hydrogen-producing alloy blank; S3: heat treat the hydrogen-producing alloy blank under the condition of annealing at 250°C for 2h to obtain a hydrogen-producing alloy.

[0054] In step S1, the mass component of Al is 93.5%, the mass component of Ga is 0.5%, the mass component of In is 1%, the mass component of Sn is 2%; the mass component of Zn is 2%, and the mass component of Cu is 1%.

[0055] The comparative curve of the hydrogen production performance of the hydrogen-producing alloy of Example 1 and the hydrogen-producing alloy of Comparative Example 1 is shown in Figure 3 , wherein curve I is the hydrogen production curve of the hydrogen-producing alloy of Example 1, and it can be seen that the total hydrogen production is close to 1240 mL·g-1; curve II is the hydrogen production curve of the hydrogen-producing alloy of Comparative Example 1, and it can be seen that the total hydrogen production is 850 mL·g -1 ; curve III is the instantaneous hydrogen production rate curve of the hydrogen-producing alloy of Example 1, and it can be seen that the peak hydrogen production rate is greater than 18 mL·min -1 ·g -1 , t1 is the induction time of the hydrogen production of the hydrogen-producing alloy of Example 1, which is only 8 seconds, less than 15 seconds, and curve IV is the instantaneous hydrogen production rate curve of the hydrogen-producing alloy of Comparative Example 1, t2 is the induction time of the hydrogen production of the hydrogen-producing alloy of Comparative Example 1, which is greater than 60 seconds.

[0056] The hydrogen production alloy obtained in Example 1 has an extremely short induction time of less than 15 seconds in terms of reaction starting speed, and the cumulative hydrogen production curve of the hydrogen production alloy obtained in Example 1 can be seen to rise steeply from the origin in curve I. The hydrogen production alloy obtained in Comparative Example 1 has an induction time of more than 60 seconds, and the cumulative hydrogen production curve of the hydrogen production alloy obtained in Comparative Example 1 has a gentle slope at the initial stage in curve II, which indicates that the surface oxide film of the hydrogen production alloy obtained in Comparative Example 1 is not effectively destroyed, and the reaction is difficult to start. The surface oxide film of the hydrogen production alloy obtained in Example 1 is effectively destroyed, and the reaction starts very quickly. In terms of reaction kinetics, the instantaneous hydrogen production rate curve of the hydrogen production alloy obtained in Example 1 presents a high and sharp peak of more than 18 mL·min -1 ·g -1 , which indicates the explosive initial reaction brought by the nanoscale cathode phase, and then the rate decays, but still maintains at a relatively high level, which benefits from the sustainable reaction channel provided by the micrometer-scale eutectic network. The instantaneous hydrogen production rate curve of the hydrogen production alloy obtained in Comparative Example 1 has a low and rapid decay rate peak, which indicates that the reaction dynamics of the hydrogen production alloy obtained in Comparative Example 1 is insufficient and prone to passivation. In terms of conversion efficiency, the cumulative hydrogen production of the hydrogen production alloy obtained in Example 1 is as high as 1235 mL / g within 60 minutes, and the aluminum conversion rate is close to 100%. The final hydrogen production of the hydrogen production alloy obtained in Comparative Example 1 is only about 850 mL / g, and the conversion rate is less than 70%, and a large amount of aluminum is not involved in the reaction due to passivation.

[0057] The results of the cycle stability test of the hydrogen production alloy of Example 1 and the hydrogen production alloy of Comparative Example 1 are shown in FIG. 3. Figure 4The curve I is the 50-cycle stability test curve of the hydrogen-producing alloy of Example 1; the curve II is the 50-cycle stability test curve of the hydrogen-producing alloy of Comparative Example 1; the curve III is the 100-cycle stability test curve of the hydrogen-producing alloy of Example 1; and the curve IV is the 100-cycle stability test curve of the hydrogen-producing alloy of Comparative Example 1. After 100 complete hydrogen production-regeneration cycles, the hydrogen production of the hydrogen-producing alloy of Example 1 can still be maintained at 1180 mL·g-1, the hydrogen production is still more than 95%, and the attenuation is less than 5%, which means that the multi-scale electrochemical microcell structure is well maintained during the repeated chemical reaction and heat treatment regeneration process, the loss of effective elements (such as Ga, In, Sn, Ni, and Co) is extremely low, and the active reaction interface is continuously maintained. The hydrogen-producing alloy of Comparative Example 1 shows serious performance attenuation, and the hydrogen production retention rate is less than 60% after 100 cycles, and the attenuation rate is more than 40%; the attenuation mainly occurs in the first 50 cycles, and the attenuation rate is more than 20%; which indicates that the initial structure is unstable, and the active elements are easy to evaporate, oxidize or irreversibly segregate and agglomerate during the regeneration process, resulting in rapid deactivation of active sites and continuous reduction of reaction interface. The shadow area between the curve III and the curve IV directly highlights the huge advantage range of the hydrogen-producing alloy of Example 1 in the cycle life.

[0058] In summary, the present embodiment successfully solves the technical problems of slow start, low rate and poor conversion in aluminum-water reaction through multi-scale structure design.

[0059] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A hydrogen-producing alloy of a multi-scale electrochemical microgalvanic structure, characterized in that, The hydrogen production alloy comprises an aluminum matrix, a nanoscale cathode phase and a micrometer-scale cathode network; The nanoscale cathode phase is an intermetallic compound distributed in the aluminum matrix; The micrometer-scale cathode network is a Ga-In-Sn eutectic alloy continuously distributed along the grain boundaries of the aluminum matrix; The aluminum matrix is an anode phase; The aluminum matrix, the nanoscale cathode phase and the micrometer-scale cathode network form a multi-scale microcell structure.

2. The hydrogen-producing alloy of claim 1, wherein, The intermetallic compound is one or more of Al3Ni, Al3(Ni, Co).

3. The hydrogen-producing alloy of claim 1, wherein, The particle size of the intermetallic compound is 20 nm to 100 nm; and / or The areal density of the intermetallic compound is ≥ 1 x 10 5 mm -2 .

4. The hydrogen-producing alloy of claim 1, wherein The width of the Ga-In-Sn eutectic alloy is 0.5 μm to 2.0 μm; and / or The Ga-In-Sn eutectic alloy has a through degree of ≥ 90%.

5. The hydrogen-producing alloy of claim 1, wherein The Ga-In-Sn eutectic alloy further comprises one or more of Bi and Zn.

6. The hydrogen-producing alloy of claim 2, wherein The atomic ratio of Co and Ni in the intermetallic compound is 0 to 0.

5.

7. The hydrogen-producing alloy of claim 1, wherein The mass ratio of Ga, In and Sn in the Ga-In-Sn eutectic alloy is 65 to 80: 10 to 20: 5 to 20.

8. The hydrogen production alloy of claim 5, wherein in the Ga-In-Sn eutectic alloy, the content of Bi is ≤ 1 at%, and the content of Zn is ≤ 1 at%.

9. A method for preparing a hydrogen-evolving alloy of a multi-scale electrochemical microgalvanic structure for preparing a hydrogen-evolving alloy according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: S10: mixing aluminum powder, element powder for forming the intermetallic compound and a grain refiner to obtain a mixed powder; S20: performing spark plasma sintering on the mixed powder to obtain the aluminum matrix with grain boundary channels; S30: under the protection of an inert atmosphere, pressing the Ga-In-Sn eutectic alloy to infiltrate into the grain boundary channels of the aluminum matrix to obtain the hydrogen production alloy.

10. The method of claim 9, wherein, The temperature of the spark plasma sintering is 400°C to 550°C; the holding time of the spark plasma sintering is 2 min to 10 min; and / or The pressure of the pressing infiltration is 0.5 MPa to 5 MPa; and the temperature of the pressing infiltration is 80°C to 140°C.

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