Ultra-dispersion storage type solid-liquid two-phase gallium-based alloy catalyst and preparation method thereof

Abstract

The invention discloses an ultra-dispersion storage type solid-liquid two-phase gallium-based alloy catalyst and a preparation method thereof. The catalyst takes liquid metal gallium as a storage container, and binary gallium-based alloy is uniformly dispersed in the liquid metal gallium. The ultra-dispersed storage type gallium-based alloy catalyst is prepared through step-by-step ball milling, gradient heating, gradient cooling and grinding redispersion, and uniform distribution of gallium-based alloy in liquid metal gallium is achieved. An internal alloy is segregated on the surface of liquid metal Ga through an electrochemical activation means, and efficient catalytic reaction is achieved. According to the storage type catalyst prepared by the process, the internal alloy is uniformly dispersed, is not agglomerated, and can be segregated on the surface of Ga for multiple times, so that the effect of storing sites is effectively realized. The segregated alloy is in a cluster shape, and a large number of agglomerated blocks do not exist. The ultra-dispersed storage type solid-liquid two-phase gallium-based alloy catalyst can realize repeated reactivation after surface sites fall off and are inactivated, so that internal storage sites are separated out again, and the catalytic activity is recovered.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalytic materials technology, and relates to a gallium-based alloy catalyst for catalytic reactions and its preparation method, particularly to an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst and its preparation method. Background Technology

[0002] Hydrogen energy, as a clean energy source, has attracted widespread attention. Among its applications, hydrogen production via water electrolysis utilizes renewable energy to achieve zero carbon emissions, representing true "green hydrogen" production. Currently, commercially available platinum (Pt)-based catalysts are scarce and costly, making large-scale applications difficult, necessitating the development of non-precious metal alternatives. Nickel-based materials, as the most ideal non-precious metal hydrogen evolution catalysts, have become a current research hotspot. Most mainstream nickel-based catalysts are solid-state catalysts, achieving efficient hydrogen evolution by anchoring active Ni sites on a rigid support. However, due to the rigid support structure of solid catalysts, when surface catalytic sites face problems such as dissolution, detachment, poisoning, and deactivation, the internal Ni sites cannot migrate to the surface to regenerate the deactivated sites, typically requiring complex high-temperature or chemical treatments to restore surface activity. Furthermore, after preparation, the inherent active sites on the surface of a solid catalyst are fixed, making it difficult to control the catalytic reaction process by dynamically adjusting the catalyst structure during production. This rigid structure also significantly limits the development of intelligent operation in the hydrogen evolution reaction process.

[0003] In recent years, liquid gallium (Ga), a metallic material with liquid flowability at room temperature (melting point 29.8℃), has attracted widespread attention in the field of catalysis. Although Ga itself does not possess highly efficient catalytic activity, it often plays a key auxiliary role in catalytic reactions. By mixing active metals (such as Ni) with Ga, catalysts with highly efficient catalytic activity can be prepared. Furthermore, the liquid-liquid interface between liquid Ga and the reaction solution allows Ga's unique interfacial tension characteristics and flowability to be utilized, which can promote the development of novel liquid catalysts. Current research mainly focuses on the preparation of single-phase liquid gallium-based catalysts by adding active metals, with the migration and flow of atomic-level sites in Ga effectively improving catalytic activity. However, due to the extremely small site scale, it is difficult to achieve macroscopic dynamic control of the catalyst. Moreover, because the amount of active metal in single-phase liquid gallium-based catalysts is extremely low (mostly one ten-thousandth), the activity is difficult to maintain in the long term, and once deactivated, site activity cannot be restored. This severely limits the further development of liquid gallium-based catalysts.

[0004] Therefore, this invention develops a liquid gallium-based catalyst with internally dispersed alloy particles in liquid Ga, increasing the amount of active metal added. Taking Ni as an example, utilizing the interfacial fluidity of Ga, electrochemical activation enables the internal gallium-nickel alloy to segregate onto the Ga surface for efficient hydrogen evolution reaction. The addition of excess Ni ensures sufficient active sites, and the "stepwise ball milling-gradient heating-gradient cooling-grinding-redispersion" preparation process ensures uniform dispersion of the internal alloy without agglomeration. The electroactivated segregated alloy exhibits dispersed nanoclusters and can segregate onto the surface multiple times. After surface sites detach, rapid electroactivated segregation can regenerate active sites. Simultaneously, the catalyst can effectively control the amount of active alloy exposed and the reaction process by macroscopically adjusting the catalyst's spreading area. This novel catalyst mode, previously unreported, holds promise for achieving continuous operation and dynamic reaction control in catalytic reactions. Summary of the Invention

[0005] This invention provides a method for preparing a superdispersed, solid-liquid two-phase gallium-based alloy catalyst, aiming to offer a new paradigm for the design and selection of novel catalysts. This invention reports a liquid gallium-based catalyst with internally dispersed alloy particles. Taking active nickel as an example, electrochemical activation can segregate the internally active gallium-nickel alloy to the surface for efficient hydrogen evolution reaction. The segregated alloy exhibits dispersed nanoclusters without significant agglomeration, allowing the internal active material to be released in multiple stages. The study fully confirms the concept of site storage, with rapid electroactivation segregation after surface site detachment regenerating the active sites. Simultaneously, the catalyst can effectively control the exposed amount of active alloy and the reaction process by adjusting the spreading area of ​​a fixed mass of catalyst. This novel catalyst mode, previously unreported, holds promise for achieving continuous operation and dynamic reaction control in catalytic reactions.

[0006] The objective of this invention is achieved through the following technical solutions: <First aspect> This invention provides a superdispersed, solid-liquid two-phase gallium-based alloy catalyst. The catalyst uses liquid metal Ga as a container, with an active binary gallium-based alloy uniformly dispersed inside as storage sites, forming a solid-liquid two-phase structure. Electroactivation allows the internal active alloy to segregate onto the Ga surface for catalytic reactions, with the precipitated alloy exhibiting nanoclusters. Due to the ultrauniform dispersion, the internal alloy does not agglomerate in large quantities and can segregate onto the surface multiple times. When surface sites detach and become inactive, the unsegregated storage alloy sites inside can be electroactivated to regenerate the surface sites and restore activity. Furthermore, by using a fixed mass of catalyst and utilizing the flowability and malleability of liquid metal, the exposed amount of internally stored active alloy can be effectively controlled by controlling its spreading area, thereby achieving different catalytic activities.

[0007] As one embodiment, the ultradispersed storage catalyst mainly consists of a liquid metal Ga reservoir and a gallium-based active alloy uniformly dispersed within the liquid metal Ga. The other active metal is one of Fe, Co, Ni, Pt, Pd, Cr, and Ru, preferably Ni. The uniformly dispersed active alloy serves as reaction sites pre-stored within the liquid metal Ga, forming a solid-liquid two-phase mixed catalyst.

[0008] As one implementation, the catalyst is electrochemically activated. Driven by electrochemistry, the internal binary gallium-based alloy segregates to the surface of liquid gallium, and the migrated alloy morphology exhibits a nanocluster structure. That is, the active gallium-based alloy sites, before electrochemical activation, are uniformly dispersed within the liquid Ga metal; however, after electrochemical activation, the originally uniformly dispersed active gallium-based alloy gradually becomes exposed on the surface of the liquid Ga metal, thus serving as active sites for the catalytic reaction. Due to the special nature of the preparation process, the exposed gallium-based alloy exhibits a nanocluster structure, without significant agglomeration.

[0009] As one implementation scheme, taking nickel as an example, the electroactivated gallium-nickel active alloy can achieve a highly efficient hydrogen evolution reaction. Furthermore, due to its ultra-uniform dispersion, the internal alloy does not agglomerate in large quantities and can be activated and segregated onto the Ga surface in multiple stages. This means that when the sites on the Ga surface detach and become deactivated, the catalyst will lose its catalytic activity in a short time. However, the unsegregated gallium-nickel alloy sites inside can be electroactivated again and resegregate onto the surface, achieving in-situ regeneration of the surface sites and restoring hydrogen evolution activity. This will restore the activity of the deactivated catalyst in situ in a short time.

[0010] As one implementation, the stored catalyst can also be electroactivated by controlling different Ga spreading surfaces according to the requirements of catalytic reaction activity, thereby exposing different numbers of active sites according to the spreading area, thus effectively adjusting the overall catalytic reaction rate, which is beneficial for dynamic control of the reaction process under actual working conditions.

[0011] <Second aspect>, the present invention also provides a method for preparing an ultradispersed, stored solid-liquid two-phase gallium-based alloy catalyst, wherein the catalyst is prepared using a "stepwise ball milling-gradient heating-gradient cooling-grinding and redispersion" process, comprising the following steps: S1. Stepwise ball milling: Under an argon protective atmosphere, the elemental active metal powder is mixed evenly with liquid Ga in 3 to 5 steps by stepwise ball milling. S2, Gradient heating: The mixture obtained in S1 is heated in an argon atmosphere from room temperature to 200~300℃ and held at that temperature for 1~2 hours; then it is heated to 500~600℃ and held at that temperature for 2~4 hours to complete the gradient heating program. S3. Gradient cooling: After the isothermal period, first cool down to 300~400℃ and hold at that temperature for 1~2 hours; then cool down to room temperature to obtain the calcined mixture. S4. Grinding and redispersing: Transfer the calcined mixture to an argon atmosphere and manually grind it for 10 to 30 minutes at a temperature of 50 to 80°C (to ensure that the internal alloy is completely and uniformly dispersed) to obtain an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst.

[0012] As one implementation scheme, in step S1, the size of the selected elemental metal powder must be <100 nm, and the mixing of the metal powder and liquid Ga must be carried out in a ball mill under an argon protective atmosphere, in 3 to 5 steps to ensure uniform mixing. This ensures that the metal powder is extremely uniformly dispersed inside Ga during the initial physical mixing stage, and that there is no large amount of agglomeration between particles, thus ensuring the formation of a uniformly dispersed alloy in the subsequent calcination process. If micron-sized alloy particles are directly added to gallium-based liquid metal, the original alloy block is too large, and the amount of alloy added is too large, resulting in a gel-like structure with poor fluidity. This invention adds a trace amount (0.1%~3.0% atomic ratio) of nano-metal powder to pure liquid Ga, and then uses a specific "stepwise ball milling-gradient heating-gradient cooling-grinding and redispersing" method to form nano-cluster alloys in situ inside liquid Ga. The overall fluidity remains good, and electro-activation can effectively activate the internal alloys to exert a catalytic effect on the Ga surface.

[0013] As one implementation, in step S1, the molar ratio of the active metal to gallium is 0.1-3%.

[0014] As one implementation scheme, in step S1, the ball milling is performed for 20-40 minutes each time. The ball-to-material ratio is 6-10:1, and the ball milling speed is 800-1200 rpm / min.

[0015] As one implementation scheme, in step S1, the elemental active metal powder is divided into 3 to 5 equal parts and then ball-milled with liquid Ga in sequence.

[0016] As one implementation scheme, in step S2, the mixture after stepwise ball milling is heated using a gradient heating method. Specifically, the temperature is first increased from room temperature to 200-300℃ at a heating rate of 3℃ / min to 10℃ / min, and held at this temperature for 1-2 hours; then, the temperature is increased to 500-600℃ at a heating rate of 3℃ / min to 10℃ / min, and held at this temperature for 2-4 hours. The initial low-temperature stage is mainly to allow the active metal element to react slowly with Ga, initially forming a fine alloy structure. This also effectively avoids the agglomeration of a large number of particles, thus preventing internal alloy clumping. The subsequent high-temperature heating stage provides more energy, allowing the alloy to react further based on the initial fine grains, forming a more ordered alloy structure.

[0017] As one implementation scheme, in step S3, after heating is completed, annealing is performed using a gradient slow-programmed cooling process. Specifically, the temperature is first lowered to 300-400°C at a cooling rate of 5-10°C / min and held at that temperature for 1-2 hours, then lowered to room temperature at a cooling rate of 2-5°C / min. This is to allow the alloy, which might be in a metastable state at high temperatures, to release and homogenize thermal stress to the maximum extent during the slow cooling process, thereby maintaining the structural integrity and independence of the alloy without causing severe agglomeration. This also provides the necessary time and driving force for the atoms to fully diffuse and rearrange according to the equilibrium phase diagram, forming a thermodynamically stable, highly crystalline target phase.

[0018] As one implementation, in step S4, the argon atmosphere is a glove box argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm.

[0019] In some embodiments, the method includes the following steps: (1) Stepwise ball milling: Weigh a certain amount of elemental metal powder according to the ratio of active metal to gallium molar ratio of 0.1-3%, divide the metal powder into 3-5 equal parts, and mix and ball mill with liquid metal Ga stepwise in an argon atmosphere for 20-40 minutes. When all the metal powder and Ga are mixed, take out the mixture and put it into a crucible.

[0020] (2) Gradient heating: The above mixture is placed in a tube furnace and heated to 200-300℃ in an argon atmosphere at a heating rate of 3℃ / min to 10℃ / min, and held at the temperature for 1-2 h; then heated to 500-600℃ at a heating rate of 3℃ / min to 10℃ / min, and held at the temperature for 2-4 h to complete the gradient heating program.

[0021] (3) Gradient cooling: After the constant temperature is completed, the temperature is first lowered to 300-400℃ at a cooling rate of 5-10℃ / min and kept constant for 1-2 hours. Then, the temperature is lowered to room temperature at a cooling rate of 2-5℃ / min to obtain the calcined mixture.

[0022] (4) Grinding and redispersing: The calcined mixture is transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 10 to 30 minutes at a temperature of 50 to 80°C to ensure that the internal alloy is completely and uniformly dispersed, thereby obtaining an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst.

[0023] <Thirdly, the application of the aforementioned ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst of the present invention, or the ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst prepared by the aforementioned method after electroactivation, in various catalytic reaction systems is within the scope of protection of the present invention. Such catalytic reactions include carbon dioxide reduction, oxygen reduction, and hydrogen evolution reaction.

[0024] The electrochemical activation is as follows: in a 0.1~2 M alkaline solution, using the catalyst as the working electrode, cyclic voltammetry (CV) is performed in the range of 0.167 ~ -0.533 V (vs. RHE) until the CV curve is stable, at which point the activation ends.

[0025] The present invention preferably uses a gallium-nickel system. The ultradispersed storage solid-liquid two-phase gallium-nickel alloy catalyst prepared is mainly used for hydrogen evolution reaction. It can effectively realize rapid in-situ regeneration of deactivated sites and dynamic control of the reaction process, and can improve the continuous operation of the reaction system.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation process of the present invention realizes an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst. The gallium-based alloy is uniformly dispersed inside liquid metal Ga. Through electroactivation, the gallium-based alloy can be exposed on the surface for catalytic reaction.

[0027] (2) The exposed active gallium-based alloys are in the form of dispersed nanoclusters. After the surface sites fall off, rapid electro-activation segregation regenerates the active sites. The catalyst can also effectively control the amount of active alloys exposed and the reaction process by adjusting the spreading area of ​​a fixed mass catalyst.

[0028] (3) The storage catalyst prepared by the present invention breaks through the limitations of all-through solid catalysts and provides a new technical and process reference for realizing continuous operation and dynamic control of reaction activity. Attached Figure Description

[0029] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 Flowchart for the preparation of ultradispersed storage solid-liquid two-phase gallium-based alloy catalysts; Figure 2 SEM images and XRD patterns of the surface of the ultradispersed solid-liquid two-phase gallium-nickel alloy catalyst after preparation; Figure 3 An overall photograph of an ultradispersed solid-liquid two-phase gallium-nickel alloy catalyst before and after electroactivation. Figure 4 SEM images and XRD patterns of the surface of an ultradispersed solid-liquid two-phase gallium-nickel alloy catalyst after electroactivation and segregation. Figure 5 Cyclic voltammetric scan curves of hydrogen evolution reaction after electroactivation of ultradispersed storage solid-liquid two-phase gallium-nickel alloy catalyst and performance curves after surface deactivation-reactivation; Figure 6 Linear voltammetric scan curves of hydrogen evolution reaction after activation of ultradispersed solid-liquid two-phase gallium-nickel alloy catalysts under different spreading areas; Figure 7 SEM image of the bulk alloy precipitated after electroactivation of a gallium-nickel catalyst prepared by a process of "stepwise ball milling-one-step heating-natural annealing-grinding and redispersion"; Figure 8 The image shows the overall composition of the gallium-copper catalyst prepared by the "stepwise ball milling-gradient heating-gradient cooling-grinding and redispersion" process before and after corresponding electroactivation. Detailed Implementation

[0030] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0031] Example 1 0.024 g of elemental Ni powder with a size <100 nm and 5.0 g of liquid gallium (molar ratio 0.5%) were selected, and a process of "stepwise ball milling - gradient heating - gradient cooling - grinding and redispersing" was adopted, as detailed in the flowchart (see flowchart for details). Figure 1 ): (1) Stepwise ball milling: Divide 0.024 g of elemental Ni powder into 3 equal parts (0.08 g each). Add the mixture to liquid metal Ga in 3 parts under an argon atmosphere. Each time, the ball-to-powder ratio is 8:1 and the ball milling speed is 1000 rpm / min for 20 minutes. When all Ni powder and Ga are mixed, take out the mixture and put it into a crucible.

[0032] (2) Gradient heating: The above mixture is placed in a tube furnace and heated from room temperature to 200 ℃ in an argon atmosphere at a heating rate of 5 ℃ / min and held at that temperature for 1 h; then heated to 500 ℃ at a heating rate of 5 ℃ / min and held at that temperature for 2 h to complete the gradient heating program.

[0033] (3) Gradient cooling: After the constant temperature is completed, the temperature is first lowered to 300 ℃ at a cooling rate of 6 ℃ / min and held at the constant temperature for 1 h. Then, the temperature is lowered to room temperature at a cooling rate of 3 ℃ / min to obtain the calcined mixture.

[0034] (4) Grinding and redispersing: The calcined mixture was transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 15 min at a temperature of 50 ℃ to ensure that the internal alloy is completely and uniformly dispersed, thereby obtaining an ultradispersed storage solid-liquid two-phase gallium-nickel alloy catalyst.

[0035] The catalyst prepared under these conditions initially had a smooth and flat surface without any segregated phases, but the XRD pattern revealed an alloy phase signal of Ga5Ni, indicating that a corresponding active alloy solid was formed and stored inside. Figure 2 The catalyst is then electrochemically activated, and the specific activation process is as follows: In a 1 M sodium hydroxide solution, using liquid metal as the working electrode, cyclic voltammetry (CV) was performed in the range of 0.167 ~ -0.533 V (vs. RHE). After 150 cycles of activation, the curve stabilized, and activation was completed.

[0036] After electroactivation, the Ga5Ni alloy stored inside is exposed on the surface of liquid Ga metal, and the originally bright droplet is wrapped by a black solid. Figure 3 The exposed Ga5Ni alloy exhibits a nanocluster structure, which is further confirmed by XRD patterns to be a Ga5Ni alloy phase. Figure 4The activated CV curve showed a significant negative current signal at a negative potential, indicating that the surface-exposed Ga5Ni alloy exhibited strong hydrogen evolution reaction performance. After removing the surface-precipitated alloy, the catalyst lost its hydrogen evolution activity. However, after the same electroactivation process, new Ga5Ni alloy would re-precipitate inside the catalyst, thus restoring catalytic activity, until the internal storage sites were completely exhausted after the 7th activation, at which point activity could no longer be restored. Figure 5 Furthermore, 0.1 g of catalyst was taken and spread in different areas (1.0 cm²). 2 1.5 cm 2 and 2.0 cm 2 The hydrogen evolution performance was gradually increased with the increase of the spreading area, indicating an increase in the number of exposed sites. The hydrogen evolution performance was spread onto copper foil and, after electroactivation, linear voltammetric scans were tested in the range of 0.167 ~ -0.533 V (vs. RHE). Figure 6 The above demonstrates the catalyst's application potential in the hydrogen evolution reaction and its characteristic of internally dispersing and storing a large amount of Ga5Ni alloy.

[0037] Example 2 0.048 g of elemental Ru powder with a size <100 nm and 5.0 g of liquid gallium (molar ratio 1.0%) were selected, and a process of "stepwise ball milling - gradient heating - gradient cooling - grinding and redispersing" was adopted, as detailed in the flowchart (see flowchart for details). Figure 1 ): (1) Stepwise ball milling: Divide 0.048 g of elemental Ru powder into 4 equal parts (0.012 g each). Add the mixture to liquid metal Ga in 4 parts under an argon atmosphere. Each time, the ball powder to material ratio is 8:1 and the ball milling speed is 1000 rpm / min for 25 minutes. When all Ru powder and Ga are mixed, take out the mixture and put it into a crucible.

[0038] (2) Gradient heating: The above mixture is placed in a tube furnace and heated from room temperature to 300 ℃ in an argon atmosphere at a heating rate of 6 ℃ / min and held at the temperature for 2 h; then heated to 600 ℃ at a heating rate of 6 ℃ / min and held at the temperature for 4 h to complete the gradient heating program.

[0039] (3) Gradient cooling: After the constant temperature is completed, the temperature is first lowered to 400 ℃ at a cooling rate of 6 ℃ / min and held at the constant temperature for 2 h. Then, the temperature is lowered to room temperature at a cooling rate of 5 ℃ / min to obtain the calcined mixture.

[0040] (4) Grinding and redispersing: The calcined mixture was transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 20 min at 90°C to ensure that the internal alloy was completely and uniformly dispersed, thus obtaining an ultradispersed storage solid-liquid two-phase gallium-ruthenium alloy catalyst.

[0041] Example 3 0.1 g of elemental Co powder with a size <100 nm and 5.0 g of liquid gallium (molar ratio 2.0%) were selected, and a process of "stepwise ball milling - gradient heating - gradient cooling - grinding and redispersing" was adopted, as detailed in the flowchart (see flowchart for details). Figure 1 ): (1) Stepwise ball milling: Divide 0.1 g of elemental Co powder into 5 equal parts (0.02 g each). Add the powder to liquid metal Ga in 5 separate batches under an argon atmosphere. Each batch is ball-to-powder ratio of 8:1 and ball milled at 1000 rpm / min for 30 minutes. When all Co powder and Ga are mixed, remove the mixture and place it in a crucible.

[0042] (2) Gradient heating: The above mixture is placed in a tube furnace and heated from room temperature to 250 ℃ in an argon atmosphere at a heating rate of 3 ℃ / min and held at the temperature for 1.5 h; then heated to 550 ℃ at a heating rate of 3 ℃ / min and held at the temperature for 3 h to complete the gradient heating program.

[0043] (3) Gradient cooling: After the constant temperature is completed, the temperature is first lowered to 350 ℃ at a cooling rate of 7 ℃ / min and held at the constant temperature for 1.5 h. Then, the temperature is lowered to room temperature at a cooling rate of 4 ℃ / min to obtain the calcined mixture.

[0044] (4) Grinding and redispersing: The calcined mixture was transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 15 min at a temperature of 60 ℃ to ensure that the internal alloy is completely and uniformly dispersed, thereby obtaining an ultradispersed storage solid-liquid two-phase gallium-cobalt alloy catalyst.

[0045] Comparative Example 1 0.024 g of elemental Ni powder with a size <100 nm and 5.0 g of liquid gallium (molar ratio 0.5%) were selected, and a process of "stepwise ball milling - one-step heating - natural annealing - grinding and redispersing" was adopted. The specific process is as follows: (1) Stepwise ball milling: Divide 0.024 g of elemental Ni powder into 3 equal parts (0.08 g each). Add the mixture to liquid metal Ga in 3 parts under an argon atmosphere. Each time, the ball-to-powder ratio is 8:1 and the ball milling speed is 1000 rpm / min for 20 minutes. When all Ni powder and Ga are mixed, take out the mixture and put it into a crucible.

[0046] (2) One-step heating: The above mixture is placed in a tube furnace and heated directly from room temperature to 500 ℃ in an argon atmosphere at a heating rate of 5 ℃ / min, and held at the temperature for 3 h.

[0047] (3) Natural annealing: After the constant temperature is completed, the mixture is naturally cooled to room temperature to obtain the calcined mixture.

[0048] (4) Grinding and redispersing: The calcined mixture was transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 15 min at a temperature of 50 ℃ to obtain the corresponding catalyst.

[0049] The catalyst prepared under these conditions, after undergoing the same electroactivation procedure as in Example 1, exhibits significant agglomeration of the segregated alloy, although it remains a Ga5Ni alloy, resulting in a large-sized bulk structure. Figure 7 In this case, the internal alloy cannot be well and uniformly dispersed, and a large amount is precipitated at once during the electroactivation process, making it impossible to achieve efficient storage of active materials.

[0050] Comparative Example 2 0.024 g of elemental Ni powder with a size <100 nm and 5.0 g of liquid Ga metal (molar ratio 0.5%) were selected, and a process of "single grinding and mixing - gradient heating - gradient cooling - grinding and redispersing" was adopted. The specific process is as follows: (1) Stepwise ball milling: 0.024 g of elemental Ni powder and 5.0 g of liquid metal Ga were mixed by physical grinding in an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm. The mixture was ground for 60 minutes until all Ni powder and Ga were mixed. The mixture was then taken out and placed in a crucible.

[0051] (2) Gradient heating: The above mixture is placed in a tube furnace and heated from room temperature to 200 ℃ in an argon atmosphere at a heating rate of 5 ℃ / min and held at that temperature for 1 h; then heated to 500 ℃ at a heating rate of 5 ℃ / min and held at that temperature for 2 h to complete the gradient heating program.

[0052] (3) Gradient cooling: After the constant temperature is completed, the temperature is first lowered to 300 ℃ at a cooling rate of 6 ℃ / min and held at the constant temperature for 1 h. Then, the temperature is lowered to room temperature at a cooling rate of 3 ℃ / min to obtain the calcined mixture.

[0053] (4) Grinding and redispersing: The calcined mixture was transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 15 min at a temperature of 50 ℃ to obtain the corresponding catalyst.

[0054] Under these conditions, the catalyst prepared in the same electroactivation process as in Example 1 also exhibits significant agglomeration of the segregated alloy, resulting in a large-sized bulk structure. In this case, the internal alloy cannot be well and uniformly dispersed, and a large amount is precipitated at once during the electroactivation process, making it impossible to achieve efficient storage of the active material.

[0055] Comparative Example 3 0.024 g of elemental Cu powder with a size <100 nm and 5.0 g of liquid gallium (molar ratio approximately 0.5%) were selected, and a process of "stepwise ball milling - gradient heating - gradient cooling - grinding and redispersing" was adopted, as detailed in the flowchart. Figure 1 ): (1) Stepwise ball milling: Divide 0.024 g of elemental Cu powder into 3 equal parts (0.08 g each). Add the mixture to liquid metal Ga in 3 parts under an argon atmosphere. Each time, the ball powder to material ratio is 8:1 and the ball milling speed is 1000 rpm / min for 20 minutes. When all Cu powder and Ga are mixed, take out the mixture and put it into a crucible.

[0056] (2) Gradient heating: The above mixture is placed in a tube furnace and heated from room temperature to 200 ℃ in an argon atmosphere at a heating rate of 5 ℃ / min and held at that temperature for 1 h; then heated to 500 ℃ at a heating rate of 5 ℃ / min and held at that temperature for 2 h to complete the gradient heating program.

[0057] (3) Gradient cooling: After the constant temperature is completed, the temperature is first lowered to 300 ℃ at a cooling rate of 6 ℃ / min and held at the constant temperature for 1 h. Then, the temperature is lowered to room temperature at a cooling rate of 3 ℃ / min to obtain the calcined mixture.

[0058] (4) Grinding and redispersing: The calcined mixture was transferred to an argon atmosphere in a glove box with a water content of <1 ppm and an oxygen content of <1 ppm, and manually ground again for 15 min at a temperature of 50 ℃ to ensure that the internal alloy is completely and uniformly dispersed, thereby obtaining an ultradispersed storage solid-liquid two-phase gallium-copper alloy catalyst.

[0059] Under these conditions, the gallium-copper alloy catalyst prepared under the same electroactivation procedure as in Example 1 showed that the internal gallium-copper alloy was difficult to segregate onto the Ga surface, and there was no obvious material coverage on the Ga surface before and after electroactivation. Figure 8 This makes it impossible to achieve the effect of storage segregation.

[0060] In summary, the catalyst of this invention uses liquid gallium metal as a storage container, with a gallium-based alloy uniformly dispersed inside. This catalyst is prepared using a "stepwise ball milling-gradient heating-gradient cooling-grinding-redispersion" process to achieve a uniform distribution of the gallium-based alloy within the liquid gallium metal. Electrochemical activation allows the internal alloy to segregate onto the surface of the liquid Ga metal, achieving a highly efficient catalytic reaction. The storage catalyst prepared by this process has a uniformly dispersed internal alloy that does not agglomerate, and can segregate onto the Ga surface multiple times, effectively achieving the storage site effect. The segregated alloy appears in clusters, without a large number of agglomerated lumps. The ultra-dispersed solid-liquid two-phase gallium-based alloy catalyst can undergo repeated reactivation processes after surface site deactivation, causing the internal storage sites to precipitate again, thereby restoring catalytic activity. Furthermore, due to the large number of nanoclusters of alloy stored internally, the number of active sites exposed on the surface can be adjusted by controlling the spreading area of ​​the liquid metal, achieving dynamic control of the catalytic reaction process, which also provides a new catalyst design paradigm.

[0061] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A superdispersed, storage-type solid-liquid two-phase gallium-based alloy catalyst, characterized in that, The catalyst uses liquid gallium metal as a container, with an active binary gallium-based alloy uniformly dispersed inside as storage sites, forming a solid-liquid two-phase structure, wherein the content of active metal atoms is 0.1~3%.

2. The ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst according to claim 1, characterized in that, In active binary gallium-based alloys, the other metal is one of Fe, Co, Ni, Pt, Pd, Cr, or Ru.

3. The ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst according to claim 1, characterized in that, The catalyst was electrochemically activated, and under the drive of electrochemistry, the internal binary gallium-based alloy segregated to the surface of liquid gallium, and the morphology of the migrated alloy was nanoclusters.

4. A method for preparing a superdispersed, stored solid-liquid two-phase gallium-based alloy catalyst as described in any one of claims 1-3, characterized in that, The catalyst is produced using a "stepwise ball milling - gradient heating - gradient cooling - grinding and redispersing" process, including the following steps: S1. Stepwise ball milling: Under an argon protective atmosphere, the elemental active metal powder is mixed evenly with liquid Ga in 3 to 5 steps by stepwise ball milling. S2, Gradient heating: The mixture obtained in S1 is heated in an argon atmosphere from room temperature to 200~300℃ and held at that temperature for 1~2 h; then it is heated to 500~600℃ and held at that temperature for 2~4 h to complete the gradient heating program. S3. Gradient cooling: After the isothermal period, first cool down to 300~400℃ and hold at that temperature for 1~2 hours; then cool down to room temperature to obtain the calcined mixture. S4. Grinding and redispersing: The calcined mixture is transferred to an argon atmosphere and manually ground at 50~80℃ for 10~30 minutes to obtain an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst.

5. The preparation method according to claim 4, characterized in that, The size of the elemental active metal powder is <100 nm; And / or, the molar ratio of the active metal to gallium is 0.1% to 3%; And / or, mix and ball mill for 20-40 minutes each time; And / or, divide the elemental active metal powder into 3 to 5 equal parts, and ball-mill it with liquid Ga in steps.

6. The preparation method according to claim 4, characterized in that, In step S2, the temperature is first increased from room temperature to 200-300℃ at a heating rate of 3℃ / min to 10℃ / min; then the temperature is increased to 500-600℃ at a heating rate of 3℃ / min to 10℃ / min. In step S3, the temperature is first lowered to 300-400℃ at a cooling rate of 5-10℃ / min; then it is lowered to room temperature at a cooling rate of 2-5℃ / min.

7. The preparation method according to claim 4, characterized in that, In step S4, the argon atmosphere is an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm.

8. The application of an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst as described in any one of claims 1 to 3, or an ultradispersed storage solid-liquid two-phase gallium-based alloy catalyst prepared by any one of claims 4 to 7 after electro-activation in a catalytic reaction system.

9. The application according to claim 8, characterized in that, The catalytic reactions include carbon dioxide reduction, oxygen reduction, and hydrogen evolution.

10. The application according to claim 8, characterized in that, The electrochemical activation is as follows: in a 0.1~2M alkaline solution, using the catalyst as the working electrode, cyclic voltammetry (CV) is performed in the range of 0.167 ~ -0.533 V (vs. RHE) until the CV curve is stable, at which point the activation ends.

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