A method for determining the intermediate reaction rate constant in an electrocatalytic and photoelectrocatalytic system

Abstract

The application discloses a kind of electrocatalysis and photoelectrocatalysis system intermediate reaction rate constant determination method, the test system of phase sensitive detection in-situ electrochemical infrared spectrum is built, the period of setting additional potential variation is carried out test operation to each cycle and obtains corresponding test data, including electrochemical data and infrared spectrum data;The test data of each cycle is classified and processed respectively, respectively time-dependent to phase-dependent conversion is carried out, obtains the infrared spectrum corresponding to different phases under corresponding cycle, solves the phase difference of corresponding cycle corresponding intermediate infrared signal;After obtaining the phase difference of intermediate infrared signal corresponding to different cycles, the intermediate reaction rate constant is solved by data fitting mode.The application establishes the relationship between intermediate signal phase difference and additional potential cycle and intermediate reaction rate constant, eliminates the interference factors to intermediate reaction rate constant, and can accurately determine the intermediate reaction rate constant in electrocatalysis and photoelectrocatalysis system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrocatalysis and photoelectrocatalysis, and particularly relates to a method for determining the reaction rate constant of an intermediate in an electrocatalysis and photoelectrocatalysis system. BACKGROUND

[0002] Electrocatalysis and photoelectrocatalysis reactions are considered to be one of the most promising ways to solve the problems of energy shortage and environmental pollution, and also one of the green and economic ways for the synthesis of various chemicals. The development and design of efficient, stable and economical electrocatalysis and photoelectrocatalysis reaction systems and catalysts depend on the basic research on related reaction systems. The study of reaction mechanism is the most important research content in basic research, which specifically includes the detection of intermediates and the study of reaction kinetics involving intermediates. Through the study of reaction mechanism, the detailed elementary reaction steps and the corresponding activation energy in the catalytic reaction process can be obtained, which can be used to design and develop ideal catalysts and catalytic systems by using advanced technologies such as machine learning, and to optimize the existing catalysts and catalytic systems to establish theoretical models.

[0003] The currently reported intermediate detection techniques are mainly in-situ spectroscopy techniques, including in-situ infrared spectroscopy, in-situ Raman spectroscopy, in-situ X-ray electron energy spectrum, in-situ X-ray absorption spectroscopy, in-situ ultraviolet-visible absorption spectroscopy, and in-situ fluorescence emission spectroscopy. However, due to the low content, short lifetime and poor stability of intermediates, the research methods for intermediate kinetics are very limited. Especially with the increase of reaction efficiency, the concentration of intermediates is lower, the lifetime is shorter, and the stability is poorer, which seriously limits the research of reaction intermediates kinetics, and leads to the problem that the research of reaction intermediates kinetics depends on the basic research on related reaction systems for electrocatalysis and photoelectrocatalysis reaction systems and catalysts.

[0004] At present, the main approaches for intermediate kinetics research are density functional theory (DFT) calculation simulation and intermediate reaction rate constant determination. Among them, the technical approaches for intermediate reaction rate constant determination include intermediate decay fitting and intermediate reaction test.

[0005] In the prior art, the DFT simulation system is too ideal and simple, and has a large gap with the actual system, so the simulation results have a large difference with the actual results. Secondly, due to the complexity of electrocatalysis and photoelectrocatalysis reaction system, high charge transfer rate, large environmental noise, and the intermediate signal and kinetics are easily disturbed by the environment, etc., the intermediate decay fitting and intermediate reaction test methods cannot be applied to the determination of the reaction rate constant of the intermediate in electrocatalysis and photoelectrocatalysis.

[0006] Therefore, it is an urgent technical problem in the field to provide a method for accurately and directly determining the intermediate reaction rate constant in an electrocatalysis and photoelectrocatalysis system, which can effectively eliminate the interference of the intermediate reaction rate constant caused by the complexity of the electrocatalysis and photoelectrocatalysis reaction system, high charge transfer rate, large environmental noise, and the intermediate signal and dynamics being easily disturbed by the environment. SUMMARY

[0007] In order to solve the above problems in the prior art, the present application provides a method for determining the intermediate reaction rate constant in an electrocatalysis and photoelectrocatalysis system. The technical problem to be solved by the present application is solved by the following technical scheme:

[0008] The method for determining the intermediate reaction rate constant in an electrocatalysis and photoelectrocatalysis system comprises:

[0009] A test system of phase-sensitive detection in-situ electrochemical infrared spectroscopy is built, and the test system comprises a time-resolved infrared spectrometer, an electrochemical workstation, a function waveform generator, a trigger controller and a data acquisition and processing device;

[0010] An applied potential for loading to the test system is set, a current period indicating a change thereof is set, and a corresponding test operation is performed to obtain test data under periodic driving of the applied potential in the current period, and the set period is changed to complete test operations in multiple different periods, wherein the test data in each period comprises electrochemical data including real-time potential, real-time current and electrochemical test time in an electrocatalysis or photoelectrocatalysis reaction process, and infrared spectrum data composed of infrared test time, wave number corresponding to different infrared test times and real-time absorbance; the electrochemical data is from the electrochemical workstation, and the infrared spectrum data is from the time-resolved infrared spectrometer;

[0011] The test data corresponding to each period are classified respectively;

[0012] The test data classified for each period are converted from time dependence to phase dependence, and then infrared spectra corresponding to different phases in the corresponding period are obtained, and phase differences of the intermediate infrared signals corresponding to the corresponding period are solved;

[0013] After the phase differences of the intermediate infrared signals corresponding to different periods are obtained, the intermediate reaction rate constant is solved by data fitting.

[0014] In an embodiment of the present application, the time-resolved infrared spectrometer is built-in with a reaction cavity for electrochemical infrared spectrum test.

[0015] In one embodiment of the present application, the reaction cavity is assembled in sequence by a cavity body, a crystal wafer with a metal layer deposited thereon, a gasket and a cavity side plate; wherein the cavity body is a cuboid, the upper surface and one side wall of which are provided with a center opening, and the cavity body is used for placing an electrolyte required in a reaction process; the crystal wafer is arranged at the side wall opening of the cavity body to contact the electrolyte; the cavity side plate is provided with an opening area, and the gasket is arranged between the crystal wafer and the cavity side plate, the gasket has a hollow area matched with the opening area of the cavity side plate, and the gasket is used for supporting the crystal wafer, so that in the assembled reaction cavity, the crystal wafer is exposed on the surface through the opening area and good sealing is ensured without liquid leakage; and the crystal wafer is used as a working electrode driven by an applied potential.

[0016] In one embodiment of the present application, the reaction cavity is further provided with a reference electrode and a counter electrode, and the reference electrode and the counter electrode contact the electrolyte.

[0017] In one embodiment of the present application, the material of the crystal wafer is selected according to infrared test requirements, and the selection range includes silicon crystal, germanium crystal, zinc selenide crystal or zinc selenide crystal with a diamond coating.

[0018] In one embodiment of the present application, before the current period corresponding to the test data under the periodic driving of the applied potential is obtained, the method further comprises:

[0019] For the current period, when the corresponding applied potential is not loaded, the background test of the reaction system corresponding to the test system is performed by using the time-resolved infrared spectrometer;

[0020] After the background test is completed, a preset electrical signal is sent from the time-resolved infrared spectrometer to the function waveform generator;

[0021] The function waveform generator outputs a corresponding waveform signal according to the input preset electrical signal;

[0022] The trigger controller triggers the electrochemical workstation to load the applied potential for the reaction system according to the current period according to the input waveform signal.

[0023] In one embodiment of the present application, the test data corresponding to each period are respectively classified, including:

[0024] For any period, the electrochemical test time t e , the real-time potential e(t e ) and the real-time current i(t e), and reading different infrared test time t IR Corresponding wave number w and real-time absorbance A(w, t IR ) at any infrared test time t IR There are multiple sets of [w, A(w, t IR )] below;

[0025] Select the time interval of data processing, and read the electrochemical test time t e , real-time potential e(t e ), real-time current i(t e ) and real-time absorbance A(w, t IR ) in the time interval in the test data as read data.

[0026] In an embodiment of the present application, the test data after the classification of each cycle is respectively converted from time dependence to phase dependence, which includes:

[0027] For any cycle, the actual length of the cycle is calculated;

[0028] According to the corresponding conversion formula, the real-time potential e(t e ), real-time current i(t e ) and real-time absorbance A(w, t IR ) in the read data are respectively converted into and , wherein is a self-defined phase, The value range of is [0, 2π];

[0029] Wherein, the corresponding conversion formula includes:

[0030]

[0031] Wherein, T represents the actual length calculated for the cycle.

[0032] In an embodiment of the present application, the infrared spectrum corresponding to different phases in the corresponding cycle is obtained, and the phase difference of the intermediate infrared signal corresponding to the corresponding cycle is solved, which includes:

[0033] For any cycle, based on the , the infrared spectrum is analyzed to determine the intermediate, and the infrared wave number w0 corresponding to the intermediate is selected;

[0034] From the data obtained from the cycle, the intermediate infrared absorption data

[0035]

[0036] computing and the phase difference of the same phase the phase difference of the same phase so as to obtain the phase difference of the intermediate infrared signal corresponding to the period

[0037] In an embodiment of the present application, after the phase difference of the intermediate infrared signal corresponding to different periods is obtained, the intermediate reaction rate constant is solved by using data fitting, comprising:

[0038] the phase difference of the intermediate infrared signal corresponding to different periods and the actual length of the corresponding period are substituted into a preset formula to obtain the intermediate reaction rate constant by data fitting; wherein the preset formula is:

[0039]

[0040] wherein T n is the actual length of the nth period indicating the change of the applied potential; is the phase difference of the intermediate infrared signal corresponding to T n ; k is the intermediate reaction rate constant.

[0041] The present application has the following beneficial effects:

[0042] In the scheme provided by the embodiments of the present application, the relationship between the phase difference of the intermediate signal and the applied potential period and the intermediate reaction rate constant is established, and a new method for measuring the intermediate reaction rate constant in the electrocatalysis and photoelectrocatalysis system by phase-sensitive in-situ electrochemical infrared spectroscopy (PSD-FTIR) is proposed. This method can effectively eliminate the interference on the intermediate reaction rate constant caused by the complexity of the electrocatalysis and photoelectrocatalysis reaction system, the high charge transfer rate, the large environmental noise, and the easy environmental interference of the intermediate signal and kinetics, and can accurately measure the intermediate reaction rate constant. This method is also the first method that can directly measure the intermediate reaction rate constant in the electrocatalysis and photoelectrocatalysis system, and provides a new research approach for studying the intermediate reaction kinetics in the electrocatalysis and photoelectrocatalysis system. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a flowchart of the method for measuring the intermediate reaction rate constant in the electrocatalysis and photoelectrocatalysis system provided by the embodiments of the present application;

[0044] Figure 2 is a flowchart of the method for measuring the intermediate reaction rate constant in the electrocatalysis and photoelectrocatalysis system provided by the embodiments of the present application;

[0045] Figure 3A structural component schematic diagram of a phase-sensitive detection in-situ electrochemical infrared spectroscopy test system according to an embodiment of the present application;

[0046] Figure 4 A schematic diagram for understanding the assembly process and structure of a reaction cavity according to an embodiment of the present application;

[0047] Figure 5 A schematic diagram for understanding the process of obtaining an intermediate reaction rate constant in a complete test in a method for determining an intermediate reaction rate constant in an electrocatalysis and photoelectrocatalysis system according to an embodiment of the present application. DETAILED DESCRIPTION

[0048] The present application will be further described in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0049] In current intermediate kinetics research, the DFT simulation system is too ideal and simple, and has a large gap with the actual system, so the simulation results have a large difference with the actual results. The shortcomings and limitations in the research of intermediate kinetics mainly manifest as follows:

[0050] (1) High calculation cost, difficult to handle large systems

[0051] DFT calculation, especially transition state search, requires a large amount of computing resources, and the calculation cost increases significantly with the increase of system size. Therefore, DFT is usually only suitable for small molecules and relatively simple systems, and it is difficult to handle complex catalytic interfaces or molecular systems containing more atoms. For large systems containing multiple species in electrocatalytic reactions, the calculation time of DFT may be too long to meet the actual demand.

[0052] (2) Unable to accurately describe non-equilibrium state and dynamic process

[0053] DFT is a ground state electronic structure theory, mainly suitable for describing the ground state structure and energy of the system, and has limited ability to describe non-equilibrium state processes and dynamic processes. It is difficult to accurately simulate the dynamic changes of the state of the intermediate in the reaction process. Especially under non-steady-state conditions of electrocatalytic reactions, the behavior of the intermediate under different potentials or different environments is difficult to simulate directly by DFT.

[0054] (3) Difficult to search and verify transition state

[0055] Transition state search is a key step in studying reaction pathways, but it is very difficult to find the exact transition state structure and energy peak, especially for complex reaction pathways or multi-step reactions, there may be multiple transition states, making the search process more complex and prone to local minimum values. Some complex reaction pathways need to be found by artificial guessing and multiple attempts to find suitable transition states, increasing the uncertainty.

[0056] (4) Limited simulation of electron transfer processes

[0057] DFT has difficulty accurately describing the kinetics of electron transfer processes, especially in electrocatalytic reactions, where the rate of electron transport and the reactivity of intermediates are coupled, while DFT can only calculate the static energy of the system. For systems containing significant electron-electron correlation effects, such as d and f electron-rich transition metals, DFT calculations often have large errors. These effects make it difficult to accurately simulate electron transfer processes and intermediate behavior.

[0058] (5) Temperature and solvent effect errors in free energy calculations

[0059] In DFT, temperature effects and solvent effects are usually introduced through simplified models or static corrections, but these methods can only approximately describe the actual conditions, especially for systems with complex solvent effects (such as aqueous solutions). The solvation models (such as PCM, SMD) relied on by free energy calculations cannot fully reflect the environment of real solutions, which can easily lead to deviations in free energy and affect the prediction of intermediate reaction kinetics.

[0060] (6) Inaccurate description of electric field and interface effects in electrocatalytic reactions

[0061] The interface of electrocatalytic reactions is significantly affected by the electric field and solvent molecules, but in DFT calculations, the electric field and interface effects are usually simulated using simple models, such as introducing a uniform electric field or assuming the electrode surface as an ideal plane. In reality, the electrode surface may have defects, surface oxidation or heteroatom doping, which can significantly affect the stability and kinetic behavior of intermediates, and the idealized treatment of DFT is difficult to accurately capture these effects.

[0062] (7) Limited handling of quantum effects and spin states

[0063] For reactions involving multiple spin states (such as free radicals or transition metal systems), DFT has limited handling of different spin states. Errors in spin states can affect the stability of intermediates and the accuracy of reaction pathways. Quantum tunneling effects can affect reaction rates in some reactions, but DFT calculations usually ignore tunneling effects, so some reaction rates may be underestimated, especially for reactions involving light atoms (such as hydrogen).

[0064] (8) Cannot directly calculate reaction rate constants

[0065] DFT can only provide energy and structure information, and cannot directly obtain reaction rate constants. It is necessary to use transition state theory, activation energy and temperature to indirectly estimate reaction rates, and this indirect estimation is greatly affected by the accuracy of transition state search and calculation conditions.

[0066] The existing technical approaches for determining the intermediate reaction rate constant include intermediate decay fitting and intermediate reaction testing.

[0067] The method for determining the intermediate rate constant by intermediate decay fitting is specifically as follows:

[0068] (1) Monitoring the change curve of the intermediate signal intensity with time

[0069] It is assumed that the initial concentration of the intermediate is [I]0, and the change of the concentration of the intermediate with time t conforms to the first-order reaction kinetics, and the equation for describing the decay of the intermediate concentration is:

[0070] [I] t = [I]0·e -kt

[0071] wherein [I] t is the concentration of the intermediate at time t, [I]0 is the initial concentration, and k is the reaction rate constant of the intermediate.

[0072] (2) Fitting the decay curve to obtain the intermediate lifetime

[0073] In experiments, the signal intensity (proportional to the concentration) of the intermediate is usually monitored. By measuring the change curve of the signal intensity with time and fitting the first-order kinetics, the lifetime (i.e., characteristic time) of the intermediate can be obtained, which is defined as τ = 1 / k. Here, τ represents the time required for the concentration of the intermediate to decay to 1 / e (about 37%) of the initial value [I]0, that is:

[0074] [I] τ = [I]0·e -1 = [I]0 / e

[0075] (3) Using the relationship between the lifetime and the rate constant to solve the rate constant

[0076] The intermediate lifetime τ obtained by fitting can be directly used to calculate the rate constant k: k = 1 / τ.

[0077] In summary, by measuring the change curve of the intermediate signal intensity with time, fitting the first-order reaction kinetics decay curve to obtain the lifetime τ, and then using the formula k = 1 / τ to calculate the reaction rate constant k of the intermediate.

[0078] The method for determining the intermediate rate constant by intermediate reaction testing is specifically as follows:

[0079] (1) Characterizing the chemical structure and morphology of the intermediate

[0080] Before starting the reaction rate measurement, the intermediate needs to be characterized to confirm its specific chemical structure and morphology (e.g. by nuclear magnetic resonance (NMR), mass spectrometry (MS), infrared spectroscopy (IR), electron microscopy (SEM / TEM), etc.). This step ensures that the object of measurement is the desired intermediate.

[0081] (2) Direct synthesis of the intermediate

[0082] The desired intermediate is prepared by chemical synthesis or purification methods to ensure that sufficient intermediate is available for subsequent experiments.

[0083] (3) Reaction test of the intermediate with oxidizing or reducing agents

[0084] Using the prepared intermediate, a suitable oxidizing or reducing agent is selected to react with the intermediate, simulating the reaction step of the intermediate in the actual catalytic process.

[0085] In the experiment, a series of different concentrations of oxidizing or reducing agents are selected, and the reaction rate of the intermediate with the oxidizing or reducing agent at each concentration is observed and measured. The rate can usually be recorded by monitoring the change in product concentration over time or the change in a certain characteristic signal in the reaction system. The curve of the reaction rate v versus the concentration [A] of the added oxidizing or reducing agent is obtained.

[0086] (4) Calculation of the reaction rate constant by the slope of the curve

[0087] The reaction of the intermediate in the catalytic reaction is usually a first-order reaction, and the rate expression is:

[0088] v = k[I][A]

[0089] Where: v is the reaction rate, k is the reaction rate constant of the intermediate, [I] is the concentration of the intermediate, and [A] is the concentration of the oxidizing or reducing agent.

[0090] When the concentration of the intermediate [I] is constant, the rate v has a linear relationship with the concentration [A] of the oxidizing or reducing agent, and the formula is:

[0091] v = k obs [A]

[0092] Where k obs = k[I] is the apparent rate constant.

[0093] According to the reaction rate curves obtained at different concentrations [A], the slope of the curve can be calculated, and the apparent rate constant k obs is obtained. Finally, the reaction rate constant k is calculated by the relationship between the concentration of the intermediate [I] and k obs : k = k obs / [I]

[0094] In summary, this method synthesizes intermediates through experiments, simulates their actual reaction conditions, measures the change of reaction rate with the concentration of oxidizing or reducing agents, and finally calculates the rate constant of the intermediate using the slope of the reaction rate curve and the concentration of the intermediate.

[0095] Existing intermediate decay fitting and intermediate reaction testing methods cannot be applied to the determination of intermediate reaction rate constants in electrocatalysis and photoelectrocatalysis. This is mainly due to the complexity of electrocatalysis and photoelectrocatalysis reaction systems, which includes the following aspects:

[0096] (1) Difficulty in intermediate detection and characterization

[0097] On the electrocatalytic and photoelectrocatalytic interface, the concentration of intermediates is usually low, and the interface electric field will affect the stability of the intermediates. This increases the difficulty of signal detection, for example, in the case of weak signal, the signal of the intermediate detected by spectroscopy or other methods will be disturbed by noise, making it difficult to accurately measure the decay rate of the intermediate. The decay fitting method, which requires high signal intensity, is not easy to implement under such low concentration.

[0098] (2) Influence of electron transfer rate

[0099] The intermediates in electrocatalysis and photoelectrocatalysis reactions are not only controlled by the chemical reaction rate, but also by the electron transfer rate. The electron transfer rate is affected by factors such as electrode material, surface active site, etc., and may be coupled with the decay rate of the intermediate. Direct use of intermediate decay fitting method cannot distinguish the contribution of the two, which may lead to misjudgment of the rate constant.

[0100] (3) Complex interface reaction conditions

[0101] The electrocatalytic and photoelectrocatalytic reaction interface usually includes electrode, solution and intermediate, and the interaction between these components is complex. The electric field, local pH value, ion concentration and other factors on the electrocatalytic interface will affect the reaction kinetics of the intermediate, making it difficult to directly determine the actual rate constant of the intermediate reaction.

[0102] (4) Non-steady-state nature of electrochemical driven reactions

[0103] The current and potential in electrocatalysis and photoelectrocatalysis reactions are non-steady-state, especially under the conditions of scanning potential or current pulse, the generation and decay of intermediates will change with the potential. The use of intermediate decay fitting method requires stable reaction conditions, while under non-steady-state potential, the concentration and rate constant of the intermediate will be disturbed, which may lead to inaccurate fitting of the decay data.

[0104] (5) Influence of environmental factors

[0105] In the interface environment of electrocatalysis and photoelectrocatalysis, the composition of the solution (such as dissolved oxygen, proton concentration, ionic strength) will affect the generation and decay of intermediates, especially on the gas-liquid-solid three-phase interface, the diffusion rate of the gas will also become an influencing factor. The intermediate decay fitting method may not fully consider the influence of these factors, resulting in larger error in the determination result.

[0106] In view of the above problems, the present application aims to provide a method for accurately and directly determining the intermediate reaction rate constant in the electrocatalysis and photoelectrocatalysis system, which can effectively eliminate the interference of the intermediate reaction rate constant caused by the complexity of the electrocatalysis and photoelectrocatalysis reaction system, high charge transfer rate, large environmental noise, and intermediate signal and dynamics easily disturbed by the environment.

[0107] Specifically, the present application provides a method for determining the intermediate reaction rate constant in an electrocatalysis and photoelectrocatalysis system, please refer to Figure 1 and Figure 2 It is understood that the method can include the following steps:

[0108] S1, a phase-sensitive detection in-situ electrochemical infrared spectroscopy test system is built, the test system includes a time-resolved infrared spectrometer, an electrochemical workstation, a function waveform generator, a trigger controller and a data acquisition and processing device;

[0109] Please refer to Figure 3 The test system of the phase-sensitive detection in-situ electrochemical infrared spectroscopy is built, which has the characteristics of low detection limit and strong anti-interference ability. The low detection limit means that the detected substance can be detected when the content is very low, so the detection sensitivity is high. The anti-interference ability is reflected in the anti-background interference, environmental interference and other non-reaction process interference factors.

[0110] The time-resolved infrared spectrometer, the function waveform generator, the trigger controller, the electrochemical workstation and the data acquisition and processing device are connected in sequence, and at the same time, the time-resolved infrared spectrometer is also connected to the data acquisition and processing device.

[0111] The time-resolved infrared spectrometer has an electrochemical infrared spectrum test reaction cavity built-in, which is used to complete the electrochemical infrared spectrum test.

[0112] Please refer to Figure 4 The assembly process and the final structure of the reaction cavity are understood.

[0113] The reaction cavity is assembled in order by a cavity body, a crystal sheet with a metal layer deposited thereon, a gasket and a cavity side plate.

[0114] The cavity body is a cuboid, and the upper surface and one side wall thereof are provided in a center-opening manner, and the opening area is Figure 4The light blue area on the middle cavity body; the cavity body is used for placing electrolyte required by the reaction process; the electrolyte is specifically selected according to different reaction processes.

[0115] The crystal sheet is arranged at the side wall opening of the cavity body to contact the electrolyte; the size of the crystal sheet is slightly larger than the size of the opening area at the side wall opening of the cavity body to realize good sealing and fitting effect of the crystal sheet and the side wall of the cavity body.

[0116] The cavity side plate is provided with an opening area, the gasket is located between the crystal sheet and the cavity side plate, the gasket has a hollow area matched with the opening area of the cavity side plate, please see the area corresponding to the dark gray rectangular frame, the gasket is used for supporting the crystal sheet, so that in the assembled reaction cavity, the crystal sheet realizes surface exposure through the opening area and guarantees good sealing without liquid leakage;

[0117] For the assembled reaction cavity, the exposed crystal sheet is used as a working electrode driven by an applied potential.

[0118] The material of the crystal sheet is selected according to the infrared test requirement, and the selection range includes silicon crystal, germanium crystal, zinc selenide crystal or zinc selenide crystal with diamond coating, and the specific selection is not limited herein.

[0119] Referring to Figure 4 As shown in the figure, the reaction cavity is also provided with a reference electrode and a counter electrode, and the reference electrode and the counter electrode contact the electrolyte. Among them, the reference electrode is used to provide a reference value for the applied potential on the working electrode, and the counter electrode is used to cooperate with the working electrode to provide a working loop.

[0120] S2, for the applied potential loaded to the test system, set the current period indicating the change of the applied potential and perform the corresponding test operation, obtain the test data under the periodic driving of the applied potential of the current period, and change the set period to complete the test operation of multiple different periods, wherein the test data corresponding to each period includes electrochemical data containing real-time potential, real-time current and electrochemical test time in the electrocatalysis or photoelectrocatalysis reaction process, and infrared spectrum data composed of infrared test time, wave number corresponding to different infrared test time and real-time absorbance; the electrochemical data comes from the electrochemical workstation, and the infrared spectrum data comes from the time-resolved infrared spectrometer;

[0121] In the embodiment of the application, by setting the change period of the applied potential of the test system, the applied potential is loaded multiple times according to the set period, so that the test system completes the corresponding test work under the set period.

[0122] For the setting of any one cycle, the starting time, the ending time and the number of times the applied potential needs to be changed according to the cycle can be set.

[0123] It should be noted that before the current cycle corresponding to the applied potential is set and the corresponding test operation is performed to obtain the test data of the reaction system under the periodic driving of the applied potential, the method further comprises:

[0124] 1) For the current cycle, the time-resolved infrared spectrometer is used to perform background testing on the corresponding reaction system of the test system without loading the corresponding applied potential;

[0125] That is, for each cycle set, background testing is needed before the corresponding test operation is performed. Since the infrared spectrum absorbance is determined according to the formula A = log(I0 / I), where A is the absorbance, I0 is the recorded transmitted light intensity in the background spectrum, and I is the recorded transmitted light intensity in the sample spectrum. Therefore, background testing is used to provide test basis data for infrared spectrum testing, so that corresponding infrared spectrum data can be obtained in subsequent test operations.

[0126] 2) After the background testing is completed, the time-resolved infrared spectrometer sends a preset electrical signal to the function waveform generator;

[0127] 3) The function waveform generator outputs a corresponding waveform signal according to the input preset electrical signal;

[0128] 4) The trigger controller triggers the electrochemical workstation to load the applied potential to the reaction system according to the current cycle according to the input waveform signal.

[0129] Steps 2) to 4) above are essentially triggering the corresponding test operation after the background testing is completed. Triggering the corresponding test operation is to trigger the electrochemical workstation to apply the periodic applied potential corresponding to the current cycle to the test system, that is, the applied potential is repeatedly applied according to the current cycle multiple times, and time-resolved in-situ infrared spectrum detection is performed at the same time. Among them, after the electrochemical workstation is triggered, it will immediately apply periodic potential change to drive electrochemical reaction and synchronously collect electrochemical data, and the time-resolved infrared spectrometer will also output infrared spectrum data after time-resolved in-situ infrared spectrum detection.

[0130] Among them, the preset electrical signal can be a preset high-voltage signal, which is set by the function waveform generator.

[0131] For each cycle set, corresponding test data can be obtained, which is from the electrochemical workstation, as electrochemical data, including real-time potential e(t e ), real-time current i(t e ), electrochemical test time t e , etc. during the electrocatalytic or photoelectrocatalytic reaction process; and which is from the time-resolved infrared spectrometer, as infrared spectrum data, including infrared test time t IR , corresponding wave number w and real-time absorbance A(w, t IR ) at different infrared test time t IR . Wherein, there are multiple groups of [w, A(w, t IR )] at any infrared test time t IR . As described above, in the infrared test, A(w, t IR ) is directly obtained by using the related data of the corresponding background test.

[0132] S3, the test data corresponding to each cycle is classified and processed respectively;

[0133] Specifically, this step can include:

[0134] S31, for any cycle, reading the electrochemical test time t e , real-time potential e(t e ) and real-time current i(t e ) in the electrochemical data corresponding to the cycle, and reading the corresponding wave number w and real-time absorbance A(w, t IR ) at different infrared test time t IR in the infrared spectrum data, wherein there are multiple groups of [w, A(w, t IR )] at any infrared test time t IR , embodied in the form of two-dimensional data;

[0135] Specifically, for the current cycle, the start time and end time of the electrochemical test and the infrared test are consistent. In the electrochemical test, periodic testing will be performed according to the current cycle, and according to the different sampling times, there will be multiple electrochemical test times t e , each electrochemical test time t e corresponding to the collected real-time potential e(t e ) and real-time current i(t e ). In the infrared test, there will also be multiple sampling times, i.e. infrared test time t IR , and multiple groups of [w, A(w, t IR )] are collected under each t IR . Since the sampling frequencies of the electrochemical test and the infrared test are different, the electrochemical test time te and infrared test time t IR are not one-to-one correspondence.

[0136] S32, selecting a time interval for data processing, and reading the electrochemical test time t in the time interval in the test data e , real-time potential e(t e ), real-time current i(t e ) and real-time absorbance A(w, t IR ) as read data.

[0137] The time interval for data processing can be selected according to the requirements of a time interval corresponding to the start time to the end in the test data, and the specific time interval is not limited herein.

[0138] S4, the test data of each cycle after classification processing is respectively converted from time dependence to phase dependence, and then the infrared spectrum corresponding to different phases under the corresponding cycle is obtained, and the phase difference of the intermediate infrared signal corresponding to the corresponding cycle is solved;

[0139] Specifically, the test data of each cycle after classification processing is respectively converted from time dependence to phase dependence, which can include the following steps:

[0140] 1) For any cycle, calculate the actual duration of the cycle;

[0141] As mentioned earlier, when setting each cycle, it is not actually directly setting the actual duration of the cycle. One of the setting methods is to set the start time, end time and the number of times the applied potential changes according to this cycle. Then for a set cycle, the actual duration of the cycle can be calculated according to these data, that is, (end time-start time) / the number of times the applied potential changes according to this cycle. Of course, since the way of setting the cycle is not limited to the one shown above, the way of calculating the actual duration of the cycle is also not unique. No matter how the periodically changing applied potential is set, as long as a method of calculating the actual duration of a cycle can be included in the protection scope of the present application.

[0142] 2) According to the corresponding conversion formula, the real-time potential e(t e ), real-time current i(t e ) and real-time absorbance A(w, t IR ) in the read data are respectively converted to and wherein, is a self-defined phase, the value range of is [0, 2π]; is selected multiple times, and the specific value in the value range each time is not limited.

[0143] The corresponding conversion formula includes:

[0144]

[0145] Wherein, T represents the actual duration calculated by the period.

[0146] Specifically, the infrared spectrum corresponding to different phases under the corresponding period is obtained, and the phase difference of the intermediate infrared signal corresponding to the corresponding period is solved, which can include the following steps:

[0147] ① For any period, based on the infrared spectrum under different phases The intermediate is determined by analyzing the infrared spectrum, and the infrared wave number w0 corresponding to the intermediate is selected.

[0148] In this step, by analyzing the infrared spectrum under different phases The type of intermediate can be determined, and the infrared wave number w0 corresponding to the intermediate can be determined according to the corresponding relationship between the known intermediate and the infrared wave number.

[0149] ② Select the intermediate infrared absorption data corresponding to different phases from the data obtained from the period

[0150] ③ Calculate the phase difference of the same phase Thus, the phase difference of the intermediate infrared signal corresponding to the period is obtained For any period set, a corresponding phase difference

[0151]

[0152] S5, after obtaining the phase difference of the intermediate infrared signal corresponding to different periods, the intermediate reaction rate constant is solved by data fitting.

[0153] This step can include:

[0154] The phase difference of the intermediate infrared signal corresponding to different periods and the actual duration of the corresponding period are substituted into the preset formula, and the intermediate reaction rate constant is obtained by data fitting; wherein, the preset formula is:

[0155]

[0156] Wherein, the above formula takes T n as an example, T n ​to indicate the actual length of the n th cycle of the change of the applied potential; to T n the phase difference of the corresponding intermediate infrared signal; k is the intermediate reaction rate constant.

[0157] The specific data fitting can be understood in the related art, and will not be described in detail here.

[0158] The process of obtaining the intermediate reaction rate constant by performing complete tests on the embodiments of the present application can be understood from the schematic diagram of Figure 5 .

[0159] In the scheme provided by the embodiments of the present application, by establishing the relationship between the phase difference of the intermediate signal , the applied potential cycle and the intermediate reaction rate constant, a new method of phase-sensitive in-situ electrochemical infrared spectroscopy (PSD-FTIR) for determining the intermediate reaction rate constant in electrocatalysis and photoelectrocatalysis systems is proposed. This method can effectively eliminate the interference with the intermediate reaction rate constant caused by the complexity of the electrocatalysis and photoelectrocatalysis reaction system, the high charge transfer rate, the large environmental noise, and the intermediate signal and dynamics easily disturbed by the environment, and can accurately determine the intermediate reaction rate constant. This method is also the first method that can directly determine the intermediate reaction rate constant in electrocatalysis and photoelectrocatalysis systems, and provides a new research approach for studying the intermediate reaction kinetics in electrocatalysis and photoelectrocatalysis systems.

[0160] It should be noted that in the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0161] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0162] In the description of the specification, reference to "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of the phrases "in one embodiment", "in some embodiments", "an example", "a specific example", or "some examples" in various places in the specification are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Also, the terminology used in the description is for the purpose of describing particular embodiments only and is not intended to be limiting. It is also possible in the present application that

[0163] The above descriptions are only the preferred embodiment of the application, not intended to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for determining the reaction rate constant of an intermediate in an electrocatalytic and photoelectrocatalytic system, characterized in that: include: Build a test system for phase-sensitive detection of in-situ electrochemical infrared spectroscopy, which includes a time-resolved infrared spectrometer, an electrochemical workstation, a function waveform generator, a trigger controller, and data acquisition and processing equipment; For an applied potential loaded into the test system, a current cycle indicating its change is set and a corresponding test operation is performed to obtain test data under periodic drive of the applied potential corresponding to the current cycle, and the set cycle is changed to complete multiple test operations of different cycles, wherein the test data corresponding to each cycle includes electrochemical data including real-time potential, real-time current, and electrochemical test time during the electrocatalytic or photoelectrocatalytic reaction process, and infrared spectral data consisting of infrared test time, wavenumber corresponding to different infrared test times, and real-time absorbance; the electrochemical data is obtained from the electrochemical workstation, and the infrared spectral data is obtained from the time-resolved infrared spectrometer; Classify the test data corresponding to each cycle respectively; The test data after classification processing of each period are converted from time dependence to phase dependence, and then the infrared spectra corresponding to different phases in the corresponding period are obtained, and the phase difference of the intermediate infrared signal corresponding to the corresponding period is solved; After obtaining the phase difference of the intermediate infrared signal corresponding to different periods, the intermediate reaction rate constant is solved by using a data fitting method, including: substituting the phase difference of the intermediate infrared signal corresponding to different periods and the actual duration of the corresponding period into a preset formula, and performing data fitting to obtain the intermediate reaction rate constant; wherein, the preset formula is: Among them, T n Indicates the actual duration of the nth cycle of the applied potential change; T n The phase difference of the corresponding intermediate infrared signal; k is the intermediate reaction rate constant.

2. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 1, characterized in that: The time-resolved infrared spectrometer is equipped with a reaction chamber for electrochemical infrared spectroscopy testing.

3. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 2, characterized in that: The reaction chamber is assembled in sequence by a chamber body, a crystal sheet deposited with a metal layer, a gasket and a chamber side plate; wherein the chamber body is a rectangular parallelepiped, and its upper surface and one side wall are set to a central opening shape, and the chamber body is used to place the electrolyte required for the reaction process; the crystal sheet is set at the side wall opening of the chamber body to contact the electrolyte; the chamber side plate is provided with an opening area, and the gasket is located between the crystal sheet and the chamber side plate, and the gasket has a hollow area matching the opening area of ​​the chamber side plate, and the gasket is used to support the crystal sheet, so that in the assembled reaction chamber, the crystal sheet is exposed on the surface through the opening area, and is ensured to be well sealed and no leakage occurs; the crystal sheet is used as a working electrode and is driven by an external potential.

4. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 3, characterized in that: The reaction chamber is further provided with a reference electrode and a counter electrode, and the reference electrode and the counter electrode are in contact with the electrolyte.

5. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 3, characterized in that: The material of the crystal piece is selected according to the infrared test requirements, and the selection range includes silicon crystal, germanium crystal, zinc selenide crystal or zinc selenide crystal with diamond coating.

6. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 3, characterized in that: Before setting a current cycle indicating a change in an applied potential applied to the test system and performing a corresponding test operation to obtain test data corresponding to the current cycle under periodic driving of the applied potential, the method further includes: For the current cycle, when no corresponding external potential is applied, performing a background test on the reaction system corresponding to the test system using the time-resolved infrared spectrometer; After completing the background test, the time-resolved infrared spectrometer sends a preset electrical signal to the function waveform generator; The function waveform generator outputs a corresponding waveform signal according to the input preset electrical signal; The trigger controller triggers the electrochemical workstation to load an external potential on the reaction system according to the input waveform signal.

7. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 6, characterized in that: The test data corresponding to each cycle are classified and processed respectively, including: For any cycle, read the electrochemical test time t in the electrochemical data corresponding to the cycle e 、Real-time potential e(t e ) and real-time current i(t e ), and read the different infrared test times t in the infrared spectrum data IR The corresponding wave number w and real-time absorbance A(w,t IR ), where any infrared test time t IR There are multiple groups [w, A(w,t IR )]; Select the time interval for data processing and read the electrochemical test time t in the test data within the time interval e 、Real-time potential e(t e ), real-time current i(t e ) and real-time absorbance A(w,t IR ) as read data.

8. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 7, characterized in that: The test data after classification processing of each period is converted from time dependence to phase dependence, including: For any period, calculate the actual duration of the period; According to the corresponding conversion formula, the real-time potential e(t e ), real-time current i(t e ) and real-time absorbance A(w,t IR ) are converted into different phase dependent and in, For custom phase, The value range of is [0,2π]; The corresponding conversion formulas include: Where T represents the actual duration calculated for the cycle.

9. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 8, characterized in that: The obtaining of infrared spectra corresponding to different phases in the corresponding period and solving the phase difference of the intermediate infrared signal corresponding to the corresponding period includes: For any cycle, based on different phases Analyze the infrared spectrum to determine the intermediate and select the infrared wave number w0 corresponding to the intermediate; From this cycle Select the infrared absorption data of intermediates corresponding to different phases from the data calculate and the same phase Phase difference Thus, the phase difference of the intermediate infrared signal corresponding to the period is obtained

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