阅读说明：本技术 一种AgX@Ag核壳电极材料制备方法 (Preparation method of AgX @ Ag core-shell electrode material ) 是由 张宇 刘亚鹏 李开伟 张繁 李相波 邢路阔 于 2020-04-03 设计创作，主要内容包括：本发明属于电极制备技术领域,具体涉及一种AgX@Ag核壳电极材料制备方法,利用聚乙二醇对AgX进行预处理,利用巯基硅烷偶联剂对AgX进行表面改性,使AgX形核分散均匀,形貌较为规则,粒度较小,不会发生团聚,表面富含巯基活性位点,再利用弱还原剂葡萄糖缓慢还原银氨溶液得到银离子,在银还原过程中,银粒子能优先在活性位点异相成核,随后被还原出的银晶核在AgX表面定向生长,从而形成银粒包覆致密的AgX@Ag核壳材料；其原理科学可靠,制备的AgX@Ag核壳材料从液相合成角度,提高了Ag和AgX的混合程度,使Ag和AgX进行包覆接触,大大超过机械混合的接触度,具有更好的接触度和更小的电极颗粒。(The invention belongs to the technical field of electrode preparation, and particularly relates to a preparation method of an AgX @ Ag core-shell electrode material, which comprises the steps of pretreating AgX by utilizing polyethylene glycol, modifying the surface of AgX by utilizing a mercaptosilane coupling agent, enabling AgX nucleation to be uniformly dispersed, having a regular shape and a smaller particle size, not causing agglomeration, having a surface rich in mercapto active sites, slowly reducing a silver ammonia solution by utilizing a weak reducing agent glucose to obtain silver ions, wherein in the silver reduction process, the silver particles can preferentially nucleate in the active sites out of phase, and then the reduced silver crystal nuclei grow directionally on the surface of AgX, so that the AgX @ Ag core-shell material with a compact silver particle coating is formed; the principle is scientific and reliable, the prepared AgX @ Ag core-shell material synthesizes the angle from the liquid phase, the mixing degree of Ag and AgX is improved, the Ag and AgX are in coating contact, the contact degree of the Ag and AgX is greatly higher than that of mechanical mixing, and the electrode material has better contact degree and smaller electrode particles.)

1. A preparation method of an AgX @ Ag core-shell electrode material is characterized in that the specific technological process comprises four steps of preparing silver halide powder, pretreating the silver halide powder, preparing modified silver halide powder and preparing the core-shell material:

(1) preparing silver halide powder: cetyl trimethyl ammonium bromide and AgNO₃Dissolving the solution A in deionized water to form a solution A, mixing NaCl, NaBr and deionized water to form a solution B, carrying out ultrasonic treatment on the solution A and the solution B, respectively carrying out magnetic stirring, slowly dropwise adding the solution B into the solution A, reacting for 2 hours at room temperature in a dark place, and carrying out centrifugal drying to obtain silver halide powder;

(2) pretreating silver halide powder: placing the silver halide powder prepared in the step (1) and distilled water in a beaker, performing ultrasonic treatment at room temperature, uniformly dispersing, heating in a water bath to control the temperature, slowly stirring for 10min to form a solution C, adding polyethylene glycol into the solution C, keeping the temperature control, electrically stirring for 1h, finishing the reaction, centrifuging, washing, and performing vacuum drying to finish the pretreatment of the silver halide powder;

(3) preparation of modified silver halide powder: placing the silver halide powder pretreated in the step (2), absolute ethyl alcohol and mercaptosilane coupling agent in a conical flask, performing ultrasonic treatment for 10min, refluxing for 6h under the condition of an oil bath at the temperature of 80 ℃, cooling, washing for 3 times by using ethyl alcohol, and performing vacuum drying to obtain modified silver halide powder;

(4) preparing a core-shell material: and (3) placing the modified silver halide powder prepared in the step (3), polyvinyl pyrrolidone, absolute ethyl alcohol and glucose solution in a beaker, performing ultrasonic dispersion for 10min to form a solution D, heating in a water bath, dropwise adding a silver ammonia solution into the solution D, after the reaction is stopped, respectively washing with water and absolute ethyl alcohol for several times, and performing vacuum drying to obtain the AgX @ Ag core-shell electrode material.

2. The method for preparing AgX @ Ag core-shell electrode material according to claim 1, wherein AgNO in the solution A involved in the step (1)₃The mass ratio of the ammonium bromide to the hexadecyl trimethyl ammonium bromide is 2.5: 1; the mass ratio of NaCl to NaBr in the solution B is 3: 1; the ultrasonic time of the solution A and the solution B is 10-20 min; the speed and the time of magnetic stirring are respectively 900-; the process of dropwise adding the solution B to the solution A took 10 min.

3. The preparation method of the AgX @ Ag core-shell electrode material according to claim 1, wherein the mass of the silver halide powder involved in the step (2) is 0.6g, the volume of distilled water is 100ml, the ultrasonic time at room temperature is 10-15min, the water bath heating is carried out to control the temperature at 50 ℃, the polyethylene glycol is polyethylene glycol-4000, the mass ratio of the polyethylene glycol to the silver halide powder is 1:1, the vacuum drying temperature is 50-60 ℃, and the drying time is 6-8 h.

4. The preparation method of the AgX @ Ag core-shell electrode material according to claim 1, wherein the mercaptosilane coupling agent involved in the step (3) is 3-mercaptopropyltrimethoxysilane, the silver halide powder pretreated in the step (2), the absolute ethyl alcohol and the mercaptosilane coupling agent are 0.5g, 120m L and 0.3m L respectively, the temperature of vacuum drying is 50 ℃, and the drying time is 6-8 hours.

5. The preparation method of the AgX @ Ag core-shell electrode material according to claim 1, wherein the mass ratio of the modified silver halide powder to the polyethylene pyrrolidone in the step (4) is 1:3, the mass ratio of the anhydrous ethanol solution to the glucose solution is 30m L and the mass ratio of the anhydrous ethanol solution to the glucose solution is 0.006 mol/L, the temperature is controlled to be 50 ℃ by heating in a water bath, the concentration of silver ions in the silver ammonia solution is 0.006 mol/L, the process of dropping the silver ammonia solution into the solution D takes 10-20min, the temperature of vacuum drying is 50-60 ℃, and the drying time is 6-8 h.

6. The preparation method of the AgX @ Ag core-shell electrode material according to any one of claims 1 to 5, characterized in that when preparing the AgX @ Ag core-shell material, firstly, polyethylene glycol is adopted to pretreat AgX powder: the polyethylene glycol molecules with the sawtooth long-chain structure are dissolved in water and then become a zigzag structure, the polyethylene glycol molecules are wound on the surface of the AgX particles to form a support, and the support is wrapped on the AgX particles: then, mercapto silane coupling agent is adopted to carry out thinning modification on the pretreated silver halide powder: forming hydrogen bonds between one O in polyethylene glycol molecules and silicon hydroxyl in alcoholysis products of mercaptosilane coupling agent molecules; finally carrying out silver coating reaction: AgX after being pretreated by polyethylene glycol and modified by a mercapto silane coupling agent contains rich mercapto active sites, silver particles can be preferentially nucleated out of phase at the active sites in the silver reduction process, and reduced silver crystal nuclei grow directionally on the surface of the AgX to form the AgX @ Ag core-shell material.

The technical field is as follows:

the invention belongs to the technical field of electrode material preparation, and particularly relates to a preparation method of an AgX @ Ag core-shell electrode material.

Background art:

when the actual potential of the metal is measured, a standard potential serving as a reference is required, one end of a potential meter is connected with the metal to be measured, the other end of the potential meter is connected with a standard potential calibration object, the potential value of the metal to be measured can be measured, and in the process, a reference electrode is indispensable.

With the development of science and technology, the requirements on the environmental interference resistance, the monitoring accuracy and other aspects of the reference electrode are continuously improved no matter in a laboratory or engineering application, so that the working environment of the reference electrode is continuously widened, and the laboratory is expanded to various complex working environments in real engineering application, such as various harsh environments, such as a sea mud environment, underground soil, deep sea high pressure and the like. Meanwhile, the performances of the reference electrode such as service life, chemical fouling resistance, high temperature and high pressure resistance and the like are greatly improved, and the application range is expanded to a plurality of fields such as corrosion rate, polarization resistance, electrochemical impedance test, electrochemical noise and component detection and monitoring.

The Ag/AgCl reference electrode preparation method comprises the steps of preparing an Ag/AgCl all-solid-state composite reference electrode disclosed in Chinese patent 201410750796.2, preparing the Ag/AgCl reference electrode and preparing an Ag/AgCl all-solid-state composite reference electrode, wherein the preparation method comprises the steps of preparing the Ag/AgCl reference electrode and preparing an Ag/AgCl all-solid-state composite reference electrode, the preparation method comprises the steps of pretreating a silver wire, taking a silver wire 11cm in diameter of 0.6mm, sequentially polishing the silver wire by 1# to 5# abrasive paper, bending the silver wire into a spiral shape with d being 3mm, sequentially cleaning the silver wire by acetone and secondary distilled water, finally activating a silver wire 355 mol thin silver nitrate solution in 0.84 min, and activating the silver wire 355-silver nitrate thin silver solution in a thin silver wire 353 min-84 minPreparing a silver plating layer: using pretreated ring silver wire as cathode, platinum electrode as anode, and using 3.75mA/cm at room temperature²Electroplating at a current density of 7.5mA/cm for 15min²The current density electroplating is carried out for 30min, the electroplated annular silver wire is sequentially cleaned by potassium iodide solution, ammonia water and secondary distilled water, the electroplating solution is prepared by taking 3g of silver nitrate, 60g of potassium iodide and 7m L of 25 percent ammonia water to be dissolved in 100m L secondary distilled water, the chlorination of the spiral silver wire is carried out by taking the spiral silver wire as an anode, a platinum electrode as a cathode and 1 mol/L hydrochloric acid solution as electrolyte, and 0.75mA/cm is firstly carried out at room temperature²The current density of (2) is electrolyzed and chlorinated for 30min, and then the concentration of the solution is 1.5mA/cm²The Ag/AgCl all-solid-state composite reference electrode is prepared by respectively adding 60g of urea and 142g of 38% formaldehyde solution into a 500m L three-neck flask provided with a stirrer and a reflux condenser, adjusting the pH value of the mixture to 7-8 by using 2 mol/L KOH solution, heating and refluxing for 2h, adding an oil-water separator between the three-neck flask and the reflux condenser, evaporating water of 40m L to obtain slurry urea-formaldehyde resin, preparing the solid-state composite reference electrode by standing the prepared Ag/AgCl electrode at the center of a mold tube (the inner diameter is 12mm), ensuring that the bottom of the Ag/AgCl electrode is separated from the bottom end of the mold tube by l-2 mm, dripping the prepared slurry urea-formaldehyde resin, polyethylene glycol and ground KCl powder into a mixture according to the ratio of 60% urea-formaldehyde resin, 20% polyethylene glycol and 20% potassium chloride powder, fully mixing the urea-formaldehyde resin, the polyethylene glycol and the potassium chloride powder, stirring the mixture uniformly, and dripping the slurry urea-formaldehyde resin, the KCl powder and the KCl powder into a No. 5/NO skeleton material, and stirring the mixture uniformly to obtain an AgCl skeleton material, wherein the AgCl material is mixed with the mixture₃After 4 drops of concentrated hydrochloric acid, the solution is quickly poured into a plastic mould tube, the plastic mould tube is placed at room temperature for 12 hours, the plastic mould tube is taken out after natural solidification, and the lower end of the plastic mould tube is polished to be smooth by 5# metallographic abrasive paper to obtain an Ag/AgCl all-solid-state combined type reference electrode; the chinese patent 201910880365.0 discloses a method for preparing a lithium ion battery reference electrode, comprising: s110, providing a lithium-philic reference electrode substrate and a current collector metal sheet adhered with a tab adhesive; s120, welding the lithium-philic reference electrode substrate to the current collector metal sheet far away from the tab glueOne end; s130, placing one end, far away from the tab glue, of the lithium-philic reference electrode substrate in molten liquid lithium for 2-5 seconds in an anhydrous and oxygen-free environment, cooling and drying, and sequentially forming an alloy layer and a lithium metal layer on the surface layer of the lithium-philic reference electrode substrate; s140, placing the lithium-philic reference electrode substrate with the alloy layer and the lithium metal layer in a first electrolyte for soaking for 1.5-2.5 hours, and forming a solid electrolyte interface film layer on the surface of the lithium metal layer, wherein the first electrolyte is a mixed solution of a secondary electrolyte and vinylene carbonate with the volume ratio concentration of 0.3-0.5%; s150, drying the lithium-philic reference electrode substrate with the solid electrolyte interface film layer to form the lithium ion battery reference electrode. However, the presence of Br in a seawater environment^-Due to Br^-With Cl^-Produce a competitive effect, and Br^-More easily react with Ag⁺AgBr with smaller solubility product is generated, thereby influencing the content of the effective component AgCl of the Ag/AgCl electrode and electrode reaction, further leading the potential of the electrode to drift and influencing the accuracy of the test result. In order to overcome the above-mentioned technical problems, the invented product can be mixed with Cl in seawater at the end of 20 th century^-And Br^-A new thermodynamically balanced solid solution of AgX (X ═ Cl, Br) is established. Experiments show that the Ag/AgX electrode has good potential stability and electrochemical performance response, small potential drift amount and small influence of light on potential, and is more suitable for marine environment.

In order to further improve the stability of the Ag/AgX electrode, the material is optimized, and the limitation of mechanical mixing is included, from the perspective of liquid phase reaction, the AgX @ Ag core-shell electrode material is prepared, so that the problem of AgX decomposition caused by illumination can be solved, Ag and AgX can be combined to the maximum extent, and the stability and the polarization resistance of the reference electrode are improved.

The invention content is as follows:

the invention aims to overcome the defects in the prior art, and develops and designs a preparation method of an AgX @ Ag core-shell electrode material so as to improve the reaction rate and the service performance of an electrode.

In order to achieve the purpose, the invention relates to a preparation method of an AgX @ Ag core-shell electrode material, which comprises the following four steps of preparing silver halide powder, pretreating the silver halide powder, preparing modified silver halide powder and preparing the core-shell material:

(1) preparing silver halide powder: cetyl trimethyl ammonium bromide and AgNO₃Dissolving the solution A in deionized water to form a solution A, mixing NaCl, NaBr and deionized water to form a solution B, carrying out ultrasonic treatment on the solution A and the solution B, respectively carrying out magnetic stirring, slowly dropwise adding the solution B into the solution A, reacting for 2 hours at room temperature in a dark place, and carrying out centrifugal drying to obtain silver halide powder;

(2) pretreating silver halide powder: placing the silver halide powder prepared in the step (1) and distilled water in a beaker, performing ultrasonic treatment at room temperature, uniformly dispersing, heating in a water bath to control the temperature, slowly stirring for 10min to form a solution C, adding polyethylene glycol into the solution C, keeping the temperature control, electrically stirring for 1h, finishing the reaction, centrifuging, washing, and performing vacuum drying to finish the pretreatment of the silver halide powder;

(3) preparation of modified silver halide powder: placing the silver halide powder pretreated in the step (2), absolute ethyl alcohol and mercaptosilane coupling agent in a conical flask, performing ultrasonic treatment for 10min, refluxing for 6h under the condition of an oil bath at the temperature of 80 ℃, cooling, washing for 3 times by using ethyl alcohol, and performing vacuum drying to obtain modified silver halide powder;

(4) preparing a core-shell material: and (3) placing the modified silver halide powder prepared in the step (3), polyvinyl pyrrolidone, absolute ethyl alcohol and glucose solution in a beaker, performing ultrasonic dispersion for 10min to form a solution D, heating in a water bath, dropwise adding a silver ammonia solution into the solution D, after the reaction is stopped, respectively washing with water and absolute ethyl alcohol for several times, and performing vacuum drying to obtain the AgX @ Ag core-shell electrode material.

AgNO in solution A according to step (1) of the present invention₃The mass ratio of the ammonium bromide to the hexadecyl trimethyl ammonium bromide is 2.5: 1; the mass ratio of NaCl to NaBr in the solution B is 3: 1; the ultrasonic time of the solution A and the solution B is 10-20 min; the speed and the time of magnetic stirring are respectively 900-; the process of dropwise adding the solution B into the solution A takes 10 min; the silver halide powder involved in the step (2) had a mass of 0.6g, a volume of distilled water of 100ml and a room temperatureThe ultrasonic time is 10-15min, the water bath heating is carried out to control the temperature to be 50 ℃, polyethylene glycol is polyethylene glycol-4000, the mass ratio of the polyethylene glycol to silver halide powder is 1:1, the vacuum drying temperature is 50-60 ℃, the drying time is 6-8h, the mercaptosilane coupling agent involved in the step (3) is 3-mercaptopropyltrimethoxysilane, the mass ratio of the silver halide powder, absolute ethyl alcohol and the mercaptosilane coupling agent pretreated in the step (2) is 0.5g, 120m L and 0.3m L respectively, the vacuum drying temperature is 50 ℃, the drying time is 6-8h, the mass ratio of the modified silver halide powder involved in the step (4) to polyvinyl pyrrolidone is 1:3, the absolute ethyl alcohol and glucose solutions are 30m L and 0.006 mol/L respectively, the water bath heating is carried out to control the temperature to be 50 ℃, the silver ion concentration in the silver ammonia solution is 0.006 mol/L, the time consumption is 10-20min, the vacuum drying temperature is 50-60 ℃, and the drying time is 6-8 h.

When the AgX @ Ag core-shell electrode material is prepared by the preparation method of the AgX @ Ag core-shell electrode material, firstly, polyethylene glycol is adopted to pretreat AgX powder: the polyethylene glycol molecules with the sawtooth long-chain structure are dissolved in water and then become a zigzag structure, the polyethylene glycol molecules are wound on the surface of the AgX particles, and a large number of polyethylene glycol molecules form a support to be wrapped on the AgX particles: then, mercapto silane coupling agent is adopted to carry out thinning modification on the pretreated silver halide powder: forming hydrogen bonds between one O in polyethylene glycol molecules and silicon hydroxyl in alcoholysis products of mercaptosilane coupling agent molecules; finally carrying out silver coating reaction: AgX after being pretreated by polyethylene glycol and modified by a mercapto silane coupling agent contains rich mercapto active sites, silver particles can be preferentially nucleated out of phase at the active sites in the silver reduction process, and reduced silver crystal nuclei grow directionally on the surface of the AgX, so that an AgX @ Ag core-shell material is formed; the method solves the problem that the AgX surface has no groups, and the metal silver nanoparticles are difficult to directionally deposit on the AgX surface due to the unmatched crystal lattices between the metal and the metal compound in the silver coating process.

Compared with the prior art, the method has the advantages that AgX is pretreated by using polyethylene glycol, surface modification is carried out on AgX by using a mercaptosilane coupling agent, AgX nucleation is uniformly dispersed, the appearance is regular, the granularity is small, agglomeration cannot occur, the surface is rich in mercapto active sites, a silver ammonia solution is slowly reduced by using a weak reducing agent glucose to obtain silver ions, silver particles can be preferentially nucleated out of phase at the active sites in the silver reduction process, and then the reduced silver crystal nucleus directionally grows on the AgX surface, so that a silver particle coated compact AgX @ Ag core-shell material is formed; the principle is scientific and reliable, the prepared AgX @ Ag core-shell material synthesizes the angle from the liquid phase, the mixing degree of Ag and AgX is improved, the Ag and the AgX are in coating contact, the contact degree of the Ag and the AgX is greatly higher than that of mechanical mixing, the Ag core-shell material has better contact degree and smaller electrode particles, the AgX decomposition phenomenon caused by illumination can be effectively reduced in the storage process, and a reference electrode prepared by the AgX @ Ag core-shell material has better long-term stability, smaller temperature coefficient and polarization resistance, and the integral service performance of the reference electrode is improved.

Description of the drawings:

fig. 1 is an SEM spectrum of the silver halide powder prepared in example 1 of the present invention.

FIG. 2 is an SEM spectrum of the AgX @ Ag core-shell electrode material prepared in example 1 of the invention.

Fig. 3 is IR spectra of silver halide powder prepared in example 1 of the present invention before pretreatment (a) and after pretreatment (b).

Fig. 4 is a comparison graph of the potential stability of a core-shell material electrode prepared by soaking a common powder tablet electrode and the novel core-shell material electrode prepared by the AgX @ Ag core-shell electrode material in seawater for 200 days according to the present invention in example 1.

FIG. 5 is a graph comparing the linear polarization curves of a conventional powder tablet electrode and a novel core-shell electrode prepared from the AgX @ Ag core-shell electrode material of example 1 of the present invention.

The specific implementation mode is as follows:

the invention is further described by way of example with reference to the accompanying drawings.