阅读说明：本技术 一种基于磁场效应测定阴极反应速率控制步骤的方法 (Method for determining cathode reaction rate control step based on magnetic field effect ) 是由 吕战鹏 董海英 许鑫和 崔同明 马佳荣 于 2021-08-12 设计创作，主要内容包括：本发明公开了一种基于磁场效应测定阴极反应速率控制步骤的方法,属于磁电化学技术领域。该方法包括：电极体系准备,工作电极在腐蚀性溶液中浸泡,自腐蚀电位测定,无磁场时测定工作电极的极化电流密度i-(0T),然后施加磁场强度为0.05-1.2T的磁场,测定磁场条件下在相同极化电位下的电流密度i-(Mag)；计算磁致电流密度Δi：Δi为相同电位下i-(Mag)和i-(0T)的差值；由磁致电流密度Δi与电位关系判断阴极反应速率控制步骤。上述实施例在电化学体系中引入磁场,通过观察Δi判断阴极反应的速率控制步骤,是一种简单、精确、对体系状态要求低的检测电化学过程中阴极反应速率控制步骤的方法。(The invention discloses a method for determining a cathode reaction rate control step based on a magnetic field effect, and belongs to the technical field of magnetoelectricity. The method comprises the following steps: preparing electrode system, immersing working electrode in corrosive solution, measuring self-corrosion potential, and measuring the polarized current density i of working electrode without magnetic field 0T Then applying a magnetic field with the magnetic field intensity of 0.05-1.2T, and measuring the current density i under the same polarization potential under the condition of the magnetic field Mag (ii) a Calculating the magneto-induced current density Δ i: Δ i is i at the same potential Mag And i 0T A difference of (d); and judging the cathode reaction rate according to the relationship between the magneto-induced current density delta i and the potential. The embodiment introduces the magnetic field into the electrochemical system, judges the cathode reaction rate control step by observing the delta i, and is a simple and accurate method for detecting the cathode reaction rate control step in the electrochemical process with low requirement on the system state.)

1. A method for determining a cathode reaction rate control step based on a magnetic field effect, the method comprising the steps of:

step one, preparing an electrode system:

the working electrode, the reference electrode and the counter electrode form a three-electrode system and are communicated with an electrochemical workstation to form an electrode system;

step two, self-corrosion potential measurement:

soaking a working electrode of an electrode system in a corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state;

step three, measuring the polarization current density:

in the absence of magnetic field, the working electrode is polarized at a certain potential, and its value i is recorded after the polarized current density is stabilized_0T(ii) a When a magnetic field is applied, the external magnetic field intensity is 0.05-1.2T, and the polarized current density i under the same potential under the condition of the magnetic field is observed and recorded_Mag；

Step four, calculating the magneto current density:

under the same polarization potential, the difference value of the polarization current density under the condition of applying a magnetic field and no magnetic field is the magneto-induced current density delta i_Mag-i_0T；

Step five, judging the rate control step:

firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i is +/-0.02 mA/cm under a certain potential²The range, and the potential delta i is not in the potential interval described in the formula I, the cathode reaction rate control step under the potential is electron transfer;

and thirdly, in the rest delta i value ranges, the cathode reaction rate is controlled by the electron transfer and material transmission steps together.

2. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: the experimental temperature for all processes was the same temperature.

3. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 2, wherein: the temperature for all processes was 25. + -. 1 ℃ at room temperature.

4. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: the measurement of the polarization current density at any potential was repeated 3 times or more.

5. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: in the third step and the fifth step, the external magnetic field intensity is 0.05T-0.4T.

6. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: in the third step and the fifth step, the external magnetic field intensity is 0.4-0.8T.

7. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: in the third step and the fifth step, the external magnetic field intensity is 0.8T-1.2T.

8. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: in the first step, the working electrode is a pure Fe electrode, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet electrode.

9. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: in the second step, the working electrode is soaked in a corrosive solution, a cathode depolarizer in the solution is a charged substance, and when the self-corrosion potential reaches a stable state and the value is recorded, the corrosive solution is Fe with the concentration of 0.05-0.1 mol/L₂(SO₄)₃The soaking time is 1.0-1.5 h, and the self-corrosion potential is-505 to-470 mV.

10. The method for determining a cathode reaction rate control step based on a magnetic field effect according to claim 1, wherein: in the third step, under the condition of no magnetic field, the working electrode is polarized under a constant potential at a certain potential, and the numerical value i of the working electrode is recorded after the current density is stabilized_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field strength is 0.4T.

Technical Field

The invention belongs to the technical field of magnetoelectric chemistry, and particularly relates to a method for determining a cathode reaction rate control step based on a magnetic field effect.

Background

Any one of the electrode reactions comprises a series of steps which are consecutive to each other, wherein the resistance is the largest, the slowest step which determines the speed of the whole electrode reaction process is called the speed control step of the electrode reaction process, and the kinetic characteristics of the whole electrode reaction are the same as the kinetic characteristics of the slowest step. Therefore, the rate control step of accurately determining the electrode reaction can effectively improve the speed of the entire chemical reaction, thereby achieving higher yield. The existing methods for judging the control step of the electrode reaction rate mainly comprise electrochemical impedance spectrum test, potentiodynamic polarization test and the like. The electrochemical impedance spectrum is a steady-state test, a system is required to reach a relatively stable state, EIS is difficult to measure for the system in an unsteady state, and the EIS measurement has high requirements on the system state; the potentiodynamic polarization curve is an accumulated result, and as the polarization potential increases, factors influencing the electrode reaction increase, and the potential area of the diffusion control region obtained from the potentiodynamic polarization curve also needs to be further accurate. Under the background, it is necessary to develop a simple, accurate method for detecting the cathode reaction rate control step in the electrochemical process with low requirements on the system state.

Disclosure of Invention

In order to solve the problems of the prior art, the invention aims to overcome the defects in the prior art and provide a method for determining the cathode reaction rate control step based on the magnetic field effect.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

a method for determining a cathode reaction rate control step based on a magnetic field effect, the method comprising the steps of:

step one, preparing an electrode system:

the working electrode, the reference electrode and the counter electrode form a three-electrode system and are communicated with an electrochemical workstation to form an electrode system;

step two, self-corrosion potential measurement:

soaking a working electrode of an electrode system in a corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state;

step three, measuring the polarization current density:

in the absence of magnetic field, the working electrode is polarized at a certain potential, and its value i is recorded after the polarized current density is stabilized_0T(ii) a When a magnetic field is applied, the external magnetic field intensity is 0.05-1.2T, and the polarized current density i under the same potential under the condition of the magnetic field is observed and recorded_Mag；

Step four, calculating the magneto current density:

under the same polarization potential, the difference value of the polarization current density under the condition of applying a magnetic field and no magnetic field is the magneto-induced current density delta i_Mag-i_aT；

Step five, judging the rate control step:

firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i is +/-0.02 mA/cm under a certain potential²The range, and the potential delta i is not in the potential interval described in the formula I, the cathode reaction rate control step under the potential is electron transfer;

and thirdly, in the rest delta i value ranges, the cathode reaction rate is controlled by the electron transfer and material transmission steps together.

Preferably, the experimental temperature of all processes of the method for determining the cathode reaction rate controlling step based on the magnetic field effect is the same temperature.

Further preferably, the temperature of all processes is 25 ± 1 ℃ at room temperature.

Preferably, the measurement of the polarization current density at any potential of the method for measuring the cathode reaction rate control step based on the magnetic field effect is repeated 3 times or more.

As a preferable technical scheme, in the third step to the fifth step, the external magnetic field intensity is 0.05T-0.4T.

As another preferred technical scheme, in the third step to the fifth step, the external magnetic field intensity is 0.4-0.8T.

In another preferred embodiment, in the third to fifth steps, the external magnetic field strength is 0.8T to 1.2T.

Preferably, in the first step, the working electrode is a pure Fe electrode, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet electrode.

Preferably, in the second step, the working electrode is soaked in a corrosive solution, the cathode depolarizer in the solution is a charged substance, and when the self-corrosion potential reaches a stable state and the value is recorded, the corrosive solution is Fe with the concentration of 0.05-0.1 mol/L₂(SO₄)₃The soaking time is 1.0-1.5 h, and the self-corrosion potential is-505 to-470 mV.

Preferably, in the third step, under the condition of no magnetic field, the working electrode is polarized under a constant potential at a certain potential, and the value i of the working electrode is recorded after the current density is stabilized_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field strength is 0.4T.

Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:

1. the invention can accurately judge the rate control step of the cathode reaction by applying a magnetic field in an electrochemical system, and regulates and controls specific rate control steps so as to effectively realize the purpose of accelerating or slowing the electrochemical reaction;

2. the invention has good measurement repeatability, and the measurement process is easy to control;

3. the method is simple and easy to implement, low in cost and suitable for popularization and application.

Drawings

FIG. 1 shows that Fe is 0.05mol/LFe₂(SO₄)₃The result of constant potential polarization in solution is shown, and the magnetic field intensity is 0.4T.

FIG. 2 shows that the Fe content is 0.05mol/LFe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density result chart show that the magnetic field intensity is 0.4T.

FIG. 3 shows that the amount of Fe in example of the present invention is 0.1mol/LFe₂(SO₄)₃The result of constant potential polarization in solution is shown, and the magnetic field intensity is 0.4T.

FIG. 4 shows that the Fe concentration of the second Fe in the example of the present invention is 0.1mol/L Fe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density result chart show that the magnetic field intensity is 0.4T.

FIG. 5 shows that the amount of tri-Fe in the example of the present invention is 0.1mol/LFe₂(SO₄)₃The result of constant potential polarization in the solution is shown, and the magnetic field intensity is 0.05T.

FIG. 6 shows that the amount of Fe is 0.1mol/L Fe in the example of the present invention₂(SO₄)₃The polarization curve in the solution and the result chart of the magneto-induced current density show that the magnetic field intensity is 0.05T.

FIG. 7 shows that the amount of Fe in the example of the present invention is 0.1mol/LFe₂(SO₄)₃The result of constant potential polarization in solution is shown, and the magnetic field intensity is 0.8T.

FIG. 8 shows that the amount of Fe in the example of the present invention is 0.1mol/L Fe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density result chart show that the magnetic field intensity is 0.8T.

FIG. 9 shows that the amount of pentaFe in the example of the present invention is 0.1mol/LFe₂(SO₄)₃The result of constant potential polarization in solution is shown, and the magnetic field intensity is 1.2T.

FIG. 10 shows that the amount of pentaFe in the example of the present invention is 0.1mol/LFe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density result chart show that the magnetic field intensity is 1.2T.

Detailed Description

The technical solutions of the present invention are further described below with reference to the following detailed description and the accompanying drawings, but the present invention is not limited thereto, and all technical solutions obtained by modifying the technical solutions of the present invention or using equivalent alternatives or equivalent variations fall within the scope of the present invention.

The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below:

the first embodiment is as follows:

in this embodiment, a method for determining the cathode reaction rate control step based on the magnetic field effect, the experimental temperature is 25 ± 1 ℃; the method of the embodiment comprises the following steps:

the method comprises the following steps: electrode system preparation

The working electrode, the reference electrode and the auxiliary electrode form a three-electrode system and are communicated with the electrochemical workstation; the working electrode is pure Fe, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet;

step two: self-corrosion potential measurement

Soaking the working electrode in corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state; the solution was 0.05mol/LFe₂(SO₄)₃The soaking time is 1.5h, and the self-corrosion potential is-500 +/-5 mV;

step three: measurement of polarization current density

Under the condition of no magnetic field, the working electrode is polarized under a certain potential at constant potential, and the value i of the working electrode is recorded after the current density is stable_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field intensity is 0.4T; the specific polarization potential is 0mV_OCP，-25mV_OCP，-50mV_OCP，-75mV_OCP，-100mV_OCP，-125mV_OCP，150mV_OCP，-175mV_OCP，-200mV_OCP. Fe at 0.05mol/LFe₂(SO₄)₃The results of constant potential polarization at different potentials in the solution are shown in FIG. 1;

step four: magneto-induced current density calculation

Under the same polarization potential, the difference value of the polarization current densities under the condition of no magnetic field and applied magnetic field is the magneto-induced current density delta i_Mag-i_0T. Fe at 0.05mol/LFe₂(SO₄)₃The current density and magneto-electric current density results at different potentials in the solution are shown in fig. 2 and table 1;

fe at 0.05mol/LFe under 0T and 0.4T conditions in Table 1₂(SO₄)₃Current density and magneto current density at different potentials in solution:

TABLE 1 example Fe at 0.05mol/LFe₂(SO₄)₃Current density and magneto-induced current density results at different potentials in solution

Step five: judging the rate control step

Firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i under a certain potential is +/-0.02 mA/cm²The potential is not in the potential interval, and the cathode reaction rate control step is electron transfer under the potential;

and thirdly, controlling the cathode reaction rate by the electron transfer and material transmission steps together in other delta i value ranges.

In this example, Fe is 0.05mol/LFe₂(SO₄)₃In solution at-100 mV_OCP～-150mV_OCPThe variation rate of the magneto-induced current density Δ i in the potential interval is less than 6%, the cathode reaction rate control step is controlled by the material transport step, and the other potential is, for example, 0mV_OCP～-50mV_OCPOr-175 mV_OCP～-250mV_OCPThe rate of change of Δ i in this potential intervalGreater than 6% and a value of Δ i greater than 0.02mA/cm at any potential in this potential interval²The cathode reaction is therefore controlled by both the electron transfer and mass transport steps. In the embodiment, the magnetic field is applied in the electrochemical system, so that the rate control step of the cathode reaction can be accurately judged, and the specific rate control step is regulated and controlled, so that the aim of effectively accelerating or slowing the electrochemical reaction is fulfilled.

Example two

This embodiment is substantially the same as the first embodiment, and is characterized in that:

in this example, a method for determining the cathode reaction rate control step based on the magnetic field effect, the experimental temperature is 25 ± 1 ℃; the method of the embodiment comprises the following steps:

the method comprises the following steps: electrode system preparation

The working electrode, the reference electrode and the auxiliary electrode form a three-electrode system and are communicated with the electrochemical workstation; the working electrode is pure Fe, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet;

step two: self-corrosion potential measurement

Soaking the working electrode in corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state; the solution was 0.1mol/LFe₂(SO₄)₃Soaking for 1h, and recording the numerical value when the self-corrosion potential reaches a stable state, wherein the self-corrosion potential is-475 +/-5 mV;

step three: measurement of polarization current density

In the absence of magnetic field, the working electrode is polarized at a constant potential under a certain potential, and the value i is recorded after the current density is stabilized_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field intensity is 0.4T; the specific polarization potential is 0mV_OCP，-50mV_OCP，-60mV_OCP，-65mV_OCP，-70mV_OCP，-75mV_OCP，80mV_OCP，-85mV_OCP，-90mV_OCP，-100mV_OCP，-110mV_OCP，-125mV_OCP，-135mV_OCP，-150mV_OCP(ii) a Fe at 0.1mol/LFe₂(SO₄)₃The results of constant potential polarization at different potentials in the solution are shown in FIG. 3;

step four: magneto-induced current density calculation

Under the same polarization potential, the difference value of the polarization current densities under the condition of no magnetic field and applied magnetic field is the magneto-induced current density delta i_Mag-i_0T. Fe at 0.1mol/LFe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density results of constant potential polarization at different potentials are shown in FIG. 4 and Table 2;

fe at 0.1mol/LFe under 0T and 0.4T conditions in Table 2₂(SO₄)₃Current density and magneto current density at different potentials in solution:

TABLE 2 example Fe at 0.1mol/LFe₂(SO₄)₃Current density and magneto-induced current density results at different potentials in solution

Step five: judging the rate control step

Firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i under a certain potential is +/-0.02 mA/cm²The potential is not in the potential interval, and the cathode reaction rate control step is electron transfer under the potential;

and thirdly, controlling the cathode reaction rate by the electron transfer and material transmission steps together in other delta i value ranges.

In this example, Fe is 0.1mol/LFe₂(SO₄)₃In solution at-60 mV_OCP～-100mV_OCPThe rate of change of the magnetocurrent density Δ i in the potential interval is less than 6%, the cathodic reaction rate control step being controlled by the mass transfer step, at the rest of the potential, e.g. 0mV_OCP～-50mV_OCPOr-110 mV_OCP～-150mV_OCPThe change rate of delta i in the potential interval is more than 6 percent, and the value of delta i in any potential in the potential interval is more than 0.02mA/cm²The cathode reaction is therefore controlled by both the electron transfer and mass transport steps. In the embodiment, the magnetic field is applied in the electrochemical system, so that the rate control step of the cathode reaction can be accurately judged, and the specific rate control step is regulated and controlled, so that the aim of effectively accelerating or slowing the electrochemical reaction is fulfilled.

EXAMPLE III

This embodiment is substantially the same as the above embodiment, and is characterized in that:

in this example, a method for determining the cathode reaction rate control step based on the magnetic field effect, the experimental temperature is 25 ± 1 ℃; the method of the embodiment comprises the following steps:

the method comprises the following steps: electrode system preparation

The working electrode, the reference electrode and the auxiliary electrode form a three-electrode system and are communicated with the electrochemical workstation; the working electrode is pure Fe, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet;

step two: self-corrosion potential measurement

Soaking the working electrode in corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state; the solution was 0.1mol/LFe₂(SO₄)₃Soaking for 1h, and recording the numerical value when the self-corrosion potential reaches a stable state, wherein the self-corrosion potential is-475 +/-5 mV;

step three: measurement of polarization current density

In the absence of magnetic field, the working electrode is polarized at a constant potential under a certain potential, and the value i is recorded after the current density is stabilized_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field intensity is 0.05T; the specific polarization potential is 0mV_OCP，-30mV_OCP，-50mV_OCP，-60mV_OCP，-70mV_OCP，-80mV_OCP，90mV_OCP，-100mV_OCP，-110mV_OCP，-120mV_OCPB, carrying out the following steps of; fe at 0.1mol/LFe₂(SO₄)₃The results of constant potential polarization at different potentials in the solution are shown in FIG. 5;

step four: magneto-induced current density calculation

Under the same polarization potential, the difference value of the polarization current densities under the condition of no magnetic field and applied magnetic field is the magneto-induced current density delta i_Mag-i_0T(ii) a Fe at 0.1mol/LFe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density results when polarization is carried out at constant potential under different potentials are shown in FIG. 6 and Table 3;

fe at 0.1mol/LFe under 0T and 0.05T conditions in Table 3₂(SO₄)₃Current density and magneto current density at different potentials in solution:

TABLE 3 example Fe at 0.1mol/LFe₂(SO₄)₃Current density and magneto-induced current density results at different potentials in solution

Step five: judging the rate control step

Firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i under a certain potential is +/-0.02 mA/cm₂The potential is not in the potential interval, and the cathode reaction rate control step is electron transfer under the potential;

and thirdly, controlling the cathode reaction rate by the electron transfer and material transmission steps together in other delta i value ranges.

In this example, Fe is 0.1mol/LFe₂(SO₄)₃In solution at-60 mV_OCP～-100mV_OCPThe variation rate of the magneto-induced current density delta i in the potential interval is less than 6%, the cathode reaction rate control step is controlled by the material transmission step, and the cathode reaction rate is controlled by 0mV at the rest potential_OCP～-50mV_OCPOr-110 mV_OCP～-120mV_OCPThe change rate of delta i in the potential interval is more than 6 percent, and the value of delta i in any potential in the potential interval is more than 0.02mA/cm²The cathode reaction is therefore controlled by both the electron transfer and mass transport steps. In the embodiment, the magnetic field is applied in the electrochemical system, so that the rate control step of the cathode reaction can be accurately judged, and the specific rate control step is regulated and controlled, so that the aim of effectively accelerating or slowing the electrochemical reaction is fulfilled.

Example four

This embodiment is substantially the same as the above embodiment, and is characterized in that:

in this example, a method for determining the cathode reaction rate control step based on the magnetic field effect, the experimental temperature is 25 ± 1 ℃; the method of the embodiment comprises the following steps:

the method comprises the following steps: electrode system preparation

The working electrode, the reference electrode and the auxiliary electrode form a three-electrode system and are communicated with the electrochemical workstation; the working electrode is pure Fe, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet;

step two: self-corrosion potential measurement

Soaking the working electrode in corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state; the solution was 0.1mol/LFe₂(SO₄)₃Soaking for 1h, and recording the numerical value when the self-corrosion potential reaches a stable state, wherein the self-corrosion potential is-475 +/-5 mV;

step three: measurement of polarization current density

In the absence of magnetic field, the working electrode is polarized at a constant potential under a certain potential, and the value i is recorded after the current density is stabilized_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field intensity is 0.8T; the specific polarization potential is 0mV_OCP，-30mV_OCP，-50mV_OCP，-60mV_OCP，-70mV_OCP，-80mV_OCP，90mV_OCP，-100mV_OCP，-110mV_OCP，-120mV_OCP，-130mV_OCP(ii) a Fe at 0.1mol/LFe₂(SO₄)₃The results of constant potential polarization at different potentials in the solution are shown in FIG. 7;

step four: magneto-induced current density calculation

Under the same polarization potential, the difference value of the polarization current densities under the condition of no magnetic field and applied magnetic field is the magneto-induced current density delta i_Mag-i_0T(ii) a Fe at 0.1mol/LFe₂(SO₄)₃The polarization curve in the solution and the magneto-induced current density results of constant potential polarization at different potentials are shown in FIG. 8 and Table 4;

fe at 0.1mol/LFe under 0T and 0.8T conditions in Table 4₂(SO₄)₃Current density and magneto current density at different potentials in solution:

TABLE 4 example four Fe at 0.1mol/LFe₂(SO₄)₃Current density and magneto-induced current density results at different potentials in solution

Step five: judging the rate control step

Firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i under a certain potential is +/-0.02 mA/cm²The potential is not in the potential interval, and the cathode reaction rate control step is electron transfer under the potential;

and thirdly, controlling the cathode reaction rate by the electron transfer and material transmission steps together in other delta i value ranges.

In this example, Fe is 0.1mol/LFe₂(SO₄)₃In solution at-60 mV_OCP～-100mV_OCPThe variation rate of the magneto-induced current density delta i in the potential interval is less than 6%, the cathode reaction rate control step is controlled by the material transmission step, and the cathode reaction rate is controlled by 0mV at the rest potential_OCP～-50mV_OCPOr-110 mV_OCP～-130mV_OCPThe change rate of delta i in the potential interval is more than 6 percent, and the value of delta i in any potential in the potential interval is more than 0.02mA/cm²The cathode reaction is therefore controlled by both the electron transfer and mass transport steps. In the embodiment, the magnetic field is applied in the electrochemical system, so that the rate control step of the cathode reaction can be accurately judged, and the specific rate control step is regulated and controlled, so that the aim of effectively accelerating or slowing the electrochemical reaction is fulfilled.

EXAMPLE five

This embodiment is substantially the same as the above embodiment, and is characterized in that:

in this example, a method for determining the cathode reaction rate control step based on the magnetic field effect, the experimental temperature is 25 ± 1 ℃; the method of the embodiment comprises the following steps:

the method comprises the following steps: electrode system preparation

The working electrode, the reference electrode and the auxiliary electrode form a three-electrode system and are communicated with the electrochemical workstation; the working electrode is pure Fe, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet;

step two: self-corrosion potential measurement

Soaking the working electrode in corrosive solution, wherein a cathode depolarizer in the solution is a charged substance, and recording the value when the self-corrosion potential reaches a stable state; the solution was 0.1mol/LFe₂(SO₄)₃Soaking for 1h, and recording the numerical value when the self-corrosion potential reaches a stable state, wherein the self-corrosion potential is-475 +/-5 mV;

step three: measurement of polarization current density

In the absence of magnetic field, the working electrode is polarized at a constant potential under a certain potential, and the value i is recorded after the current density is stabilized_0TApplying a magnetic field, observing and recording the polarization current density i at the same polarization potential under the condition of the magnetic field_Mag(ii) a The polarization time is 200s under the condition of no magnetic field, and 200s under the condition of magnetic field; the magnetic field intensity is 1.2T; the specific polarization potential is 0mV_OCP，-30mV_OCP，-50mV_OCP，-60mV_OCP，-70mV_OCP，-80mV_OCP，90mV_OCP，-100mV_OCP，-110mV_OCP，-120mV_OCP，-130mV_OCP(ii) a Fe at 0.1mol/LFe₂(SO₄)₃The results of constant potential polarization at different potentials in the solution are shown in FIG. 9;

step four: magneto-induced current density calculation

Under the same polarization potential, the difference value of the polarization current densities under the condition of no magnetic field and applied magnetic field is the magneto-induced current density delta i_Mag-i_0T(ii) a Fe at 0.1mol/LFe₂(SO₄)₃The polarization curve in solution and the magneto-induced current density results of constant potential polarization at different potentials are shown in FIG. 10 and Table 5;

fe at 0.1mol/LFe under 0T and 1.2T conditions in Table 5₂(SO₄)₃Current density and magneto current density at different potentials in solution:

TABLE 5 example pentaFe at 0.1mol/LFe₂(SO₄)₃Current density and magneto-induced current density results at different potentials in solution

Step five: judging the rate control step

Firstly, a potential interval exists on a relationship curve of the magneto-induced current density and the potential, the magneto-induced current density delta i under any two potentials in the potential interval is compared, if the change rate is less than or equal to 6%, the cathode reaction rate in the potential range is controlled by a material transmission step;

② the value of delta i under a certain potential is +/-0.02 mA/cm²The potential is not in the potential interval, and the cathode reaction rate control step is electron transfer under the potential;

and thirdly, controlling the cathode reaction rate by the electron transfer and material transmission steps together in other delta i value ranges.

In this example, Fe is 0.1mol/LFe₂(SO₄)₃In solution at-60 mV_OCP～-100mV_OCPThe variation rate of the magneto-induced current density delta i in the potential interval is less than 6%, the cathode reaction rate control step is controlled by the material transmission step, and the cathode reaction rate is controlled by 0mV at the rest potential_OCP～-50mV_OCPOr-110 mV_OCP～-130mV_OCPThe change rate of delta i in the potential interval is more than 6 percent, and the value of delta i in any potential in the potential interval is more than 0.02mA/cm²The cathode reaction is therefore controlled by both the electron transfer and mass transport steps. In the embodiment, the magnetic field is applied in the electrochemical system, so that the rate control step of the cathode reaction can be accurately judged, and the specific rate control step is regulated and controlled, so that the aim of effectively accelerating or slowing the electrochemical reaction is fulfilled.

In summary, the method for determining the cathode reaction rate control step based on the magnetic field effect in the above embodiments belongs to the field of magnetoelectricity technology. The method comprises the following steps: preparing electrode system, immersing working electrode in corrosive solution, measuring self-corrosion potential, and measuring the polarized current density i of working electrode without magnetic field_0TThen applying a magnetic field with the magnetic field intensity of 0.05-1.2T, and measuring the current density i under the same polarization potential under the condition of the magnetic field_Mag(ii) a Calculating the magneto-induced current density Δ i: Δ i is i at the same potential_MagAnd i_0TA difference of (d); and judging the cathode reaction rate according to the relationship between the magneto-induced current density delta i and the potential. The above examples introduce a magnetic field in the electrochemical system, and the determination is made by observing Δ iThe cathode reaction rate control step is a simple and accurate method for detecting the cathode reaction rate control step in the electrochemical process with low requirement on the system state.

The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the embodiments, and various changes and modifications can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitutions, as long as the purpose of the present invention is met, and the present invention shall fall within the protection scope of the present invention without departing from the technical principle and inventive concept of the present invention.