Electrocatalysis and photoelectrocatalysis system intermediate reaction rate constant determination method

Abstract

The invention discloses an electrocatalysis and photoelectrocatalysis system intermediate reaction rate constant determination method, which comprises the following steps: building a phase sensitive detection in-situ electrochemical infrared spectrum test system, setting external potential change periods, and performing test operation on each period to obtain corresponding test data, including electrochemical data and infrared spectrum data; respectively classifying the test data of each period, respectively carrying out conversion from time dependence to phase dependence, acquiring infrared spectrums corresponding to different phases in corresponding periods, and solving phase differences of intermediate infrared signals corresponding to the corresponding periods; and after the phase differences of the intermediate infrared signals corresponding to different periods are obtained, the intermediate reaction rate constant is solved in a data fitting mode. By establishing the relationship among the intermediate signal phase difference, the external potential period and the intermediate reaction rate constant, interference factors on the intermediate reaction rate constant are eliminated, and the intermediate reaction rate constant in electrocatalysis and photoelectrocatalysis systems can be accurately measured.

Description

Technical Field

[0001] The invention belongs to the field of electrocatalysis and photoelectrocatalysis, and specifically relates to a method for determining intermediate reaction rate constants of electrocatalysis and photoelectrocatalysis systems. Background Art

[0002] Electrocatalysis and photoelectrocatalysis are considered to be one of the most promising ways to solve the problems of energy shortage and environmental pollution, and one of the green economic ways to synthesize a variety of chemicals. The development and design of efficient, stable and economical electrocatalytic and photoelectrocatalytic reaction systems and catalysts depends on 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 reaction intermediates. Through the study of reaction mechanism, detailed elementary reaction steps and corresponding activation energies in the catalytic reaction process can be obtained, which can establish theoretical models for designing and developing ideal catalysts and catalytic systems using advanced technologies such as machine learning, and optimizing existing catalysts and catalytic systems.

[0003] Currently, the reported intermediate detection technologies are mainly in-situ spectroscopy technologies, including in-situ infrared spectroscopy, in-situ Raman spectroscopy, in-situ X-ray electron spectroscopy, in-situ X-ray absorption spectroscopy, in-situ ultraviolet visible absorption spectroscopy, in-situ fluorescence emission spectroscopy, etc. However, due to the low content, short life and poor stability of the intermediates, the research methods of intermediate kinetics are very limited. In particular, with the increase of reaction efficiency, the concentration of intermediates is lower, the life is shorter and the stability is worse, which seriously limits the research of reaction intermediate kinetics, making the research of reaction intermediate kinetics a problem that electrocatalytic and photoelectrocatalytic reaction systems and catalysts rely on basic research on related reaction systems.

[0004] At present, the main approaches to the study of intermediate kinetics are density functional theory (DFT) calculation simulation and determination of intermediate reaction rate constants. Among them, the technical approaches to the determination of intermediate reaction rate constants include two methods: intermediate decay fitting and intermediate reaction testing.

[0005] In the prior art, the DFT simulation system is too ideal and simple, and there is a big gap between the actual system, so the simulation results are quite different from the actual results. Secondly, due to the complexity of the electrocatalytic and photoelectrocatalytic reaction systems, high charge transfer rates, large environmental noise, and the intermediate signals and kinetics are easily disturbed by the environment, the intermediate decay fitting and intermediate reaction test methods cannot be applied to the determination of electrocatalytic and photoelectrocatalytic intermediate reaction rate constants.

[0006] Therefore, it is a technical problem to be urgently solved in this field to propose a method that can effectively eliminate the interference on the intermediate reaction rate constant caused by factors such as the complexity of the electrocatalytic and photoelectrocatalytic reaction systems, the high charge transfer rate, the large environmental noise, and the intermediate signals and kinetics being extremely susceptible to environmental interference, and to accurately and directly measure the intermediate reaction rate constants in the electrocatalytic and photoelectrocatalytic systems. Summary of the invention

[0007] In order to solve the above problems existing in the prior art, the present invention provides a method for determining the intermediate reaction rate constant of an electrocatalytic and photoelectrocatalytic system. The technical problem to be solved by the present invention is achieved by the following technical solution:

[0008] A method for determining the intermediate reaction rate constant of an electrocatalytic and photoelectrocatalytic system, comprising:

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

[0010] For the 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 a plurality of 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, and infrared spectral data consisting of infrared test time, wavenumber corresponding to different infrared test times, and real-time absorbance; the electrochemical data comes from the electrochemical workstation, and the infrared spectral data comes from the time-resolved infrared spectrometer;

[0011] Classify the test data corresponding to each cycle respectively;

[0012] The test data after classification processing of each period are respectively 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;

[0013] After obtaining the phase difference of the intermediate infrared signal corresponding to different periods, the intermediate reaction rate constant was solved by data fitting.

[0014] In one embodiment of the present invention, the time-resolved infrared spectrometer is built with a reaction chamber for electrochemical infrared spectroscopy testing.

[0015] In one embodiment of the present invention, the reaction chamber is assembled in sequence by a chamber body, a crystal sheet with a metal layer deposited thereon, a gasket and a chamber side plate; wherein the chamber body is a rectangular parallelepiped, and its upper surface and one side wall are arranged in a central opening shape, and the chamber body is used to place the electrolyte required for the reaction process; the crystal sheet is arranged 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 without leakage; the crystal sheet is used as a working electrode and is driven by an external potential.

[0016] In one embodiment of the present invention, 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.

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

[0018] In one embodiment of the present invention, before setting a current cycle indicating a change of an applied potential for loading to the test system and performing a corresponding test operation to obtain test data under periodic driving of an applied potential corresponding to the current cycle, the method further includes:

[0019] For the current cycle, when no corresponding external potential is loaded, using the time-resolved infrared spectrometer to perform a background test on the reaction system corresponding to the test system;

[0020] After completing the background test, the time-resolved infrared spectrometer sends a preset electrical signal 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 an external potential on the reaction system according to the input waveform signal.

[0023] In one embodiment of the present invention, the classification processing of the test data corresponding to each cycle includes:

[0024] 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 )];

[0025] Select a 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 the read data.

[0026] In one embodiment of the present invention, the conversion of the test data after the classification processing of each cycle from time dependence to phase dependence includes:

[0027] For any cycle, calculate the actual duration of the cycle;

[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 ) are converted into different phase dependent and in, For custom phase, The value range of is [0,2π];

[0029] The corresponding conversion formulas include:

[0030]

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

[0032] In one embodiment of the present invention, the step of obtaining infrared spectra corresponding to different phases in corresponding periods and solving the phase difference of the intermediate infrared signal corresponding to the corresponding period includes:

[0033] 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;

[0034] From this cycle Select the infrared absorption data of intermediates corresponding to different phases in the data

[0035]

[0036] calculate and the same phase Phase difference Thus, the phase difference of the intermediate infrared signal corresponding to the period is obtained

[0037] In one embodiment of the present invention, 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:

[0038] 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 data is fitted to obtain the intermediate reaction rate constant; wherein, the preset formula is:

[0039]

[0040] Among them, T n Indicates the actual duration of the nth cycle of the applied potential change; T n The corresponding phase difference of the intermediate infrared signal; k is the intermediate reaction rate constant.

[0041] Beneficial effects of the present invention:

[0042] In the solution provided by the embodiment of the present invention, by establishing the intermediate signal phase difference Based on the relationship between the applied potential period and the intermediate reaction rate constant, a new method for determining the intermediate reaction rate constant in electrocatalysis and photoelectrocatalysis systems using phase sensitive detection in situ electrochemical infrared spectroscopy (PSD-FTIR) is proposed. This method can effectively eliminate the interference on the intermediate reaction rate constant caused by factors such as the complexity of the electrocatalytic and photoelectrocatalytic reaction system, high charge transfer rate, large environmental noise, and the intermediate signal and kinetics being extremely susceptible to environmental interference, 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, providing a new research approach for studying the problem of intermediate reaction kinetics in electrocatalysis and photoelectrocatalysis systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic flow chart of a method for determining an intermediate reaction rate constant of an electrocatalytic and photoelectrocatalytic system provided by an embodiment of the present invention;

[0044] Figure 2 A schematic diagram for understanding a method for determining an intermediate reaction rate constant of an electrocatalytic and photoelectrocatalytic system provided by an embodiment of the present invention;

[0045] Figure 3A schematic diagram of the structure of a testing system for phase-sensitive detection of in-situ electrochemical infrared spectroscopy according to an embodiment of the present invention;

[0046] Figure 4 It is a schematic diagram of the assembly process and structure of the reaction chamber of an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the process of understanding the intermediate reaction rate constant obtained by performing a complete test in the method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0049] In the current research on intermediate kinetics, the DFT simulation system is too ideal and simple, which is quite different from the actual system. Therefore, the simulation results are quite different from the actual results. The shortcomings and limitations in the research on intermediate kinetics are mainly manifested as follows:

[0050] (1) High computational cost and difficult to handle large systems

[0051] DFT calculations, especially transition state searches, require a lot of computing resources, and the computational cost increases significantly with the size of the system. Therefore, DFT is usually only applicable to 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 actual needs.

[0052] (2) Unable to accurately describe non-equilibrium states and kinetic processes

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

[0054] (3) Difficulty in searching and verifying transition states

[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, where there may be multiple transition states, making the search process more complicated and prone to falling into local minima. Some complex reaction pathways require manual guessing and multiple attempts to find the right transition state, which increases uncertainty.

[0056] (4) Simulation of electron transfer process is limited

[0057] DFT has difficulty accurately describing the dynamics of electron transfer, especially in electrocatalytic reactions, where the electron transfer rate is coupled to the reaction rate of the intermediates, and DFT can usually only calculate the static energy of the system. For systems containing significant electron-electron correlation effects, such as transition metals with more d and f electrons, DFT calculations often have large errors. These effects make it difficult to accurately simulate the electron transfer process and the behavior of intermediates.

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

[0059] In DFT, temperature 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 and SMD) that free energy calculations rely on cannot fully reflect the environment of the real solution, 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 reaction is significantly affected by electric field and solvent molecules, but in DFT calculation, electric field and interface effects are usually simulated by simple models, such as introducing a uniform electric field or assuming that the electrode surface is an ideal plane. In practice, the electrode surface may have defects, surface oxidation or heteroatom doping, which will significantly affect the stability and kinetic behavior of the intermediates, and the idealized treatment of DFT is difficult to accurately capture these effects.

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

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

[0064] (8) Reaction rate constant cannot be calculated directly

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

[0066] Existing technical approaches for determining intermediate reaction rate constants include two methods: intermediate decay fitting and intermediate reaction testing.

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

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

[0069] Assuming that the initial concentration of the intermediate is [I]0, the change of its concentration with time t conforms to the first-order reaction kinetics. The equation describing the decay of the intermediate concentration is:

[0070] [I] t =[I]0·e -kt

[0071] Where: [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 of the intermediate is usually monitored (proportional to the concentration). By measuring the curve of signal intensity change over time and performing a first-order kinetic fit on it, the lifetime of the intermediate (i.e., characteristic time) can be obtained, which is defined as τ = 1 / k. Here, τ represents the time required for 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 lifetime and 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 over time, the first-order reaction kinetic decay curve is fitted to obtain the lifetime τ, and then the reaction rate constant k of the intermediate is calculated using the formula k=1 / τ.

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

[0079] (1) Characterization of the chemical structure and morphology of the intermediates

[0080] Before starting to measure the reaction rate, the intermediate needs to be characterized to confirm its specific chemical structure and morphology (such as 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 intermediates

[0082] Prepare the required intermediates by chemical synthesis or purification to ensure that sufficient intermediates can be used in subsequent experiments.

[0083] (3) Reaction test of intermediates with oxidants or reductants

[0084] Use the prepared intermediates and select appropriate oxidants or reductants to react with the intermediates to simulate the reaction steps of the intermediates in the actual catalytic process.

[0085] In the experiment, a series of different concentrations of oxidants or reductants are selected to observe and measure the reaction rate of the intermediate with the oxidants or reductants at various concentrations. The rate can usually be recorded by monitoring the change of product concentration over time or the change of a characteristic signal in the reaction system. A curve showing the reaction rate v as the concentration of the added oxidant or reductant [A] changes is obtained.

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

[0087] Usually the intermediate reaction of the catalytic reaction is 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 oxidant or reductant.

[0090] When the intermediate concentration [I] is constant, the rate v is linearly related to the oxidant or reductant concentration [A], as shown in the formula:

[0091] v = k obs [A]

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

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

[0094] In summary, this method synthesizes intermediates experimentally, simulates their actual reaction conditions, measures how the reaction rate changes with the concentration of the oxidant or reductant, and finally calculates the rate constant of the intermediate using the slope of the reaction rate curve and the intermediate concentration.

[0095] Existing intermediate decay fitting and intermediate reaction test methods cannot be applied to the determination of electrocatalytic and photoelectrocatalytic intermediate reaction rate constants. This is mainly due to the complexity of electrocatalytic and photoelectrocatalytic reaction systems, including the following aspects:

[0096] (1) Difficulty in detecting and characterizing intermediates

[0097] At the interface of electrocatalysis and photoelectrocatalysis, the concentration of intermediates is usually low, and the interfacial electric field will affect the stability of the intermediates. This increases the difficulty of signal detection. For example, in the case of weak signals, the signal of the intermediate detected by spectroscopy or other methods will be interfered by noise, making it difficult to accurately measure the decay rate of the intermediate. The decay fitting method, which has high requirements on signal intensity, is not easy to implement at such low concentrations.

[0098] (2) Influence of electron transfer rate

[0099] The intermediates in electrocatalytic and photoelectrocatalytic reactions are not only controlled by the chemical reaction rate, but also affected by the electron transfer rate. The electron transfer rate is affected by multiple factors such as electrode materials and surface active sites, and may be coupled with the decay rate of the intermediates. Directly using the intermediate decay fitting method is difficult to distinguish the contributions of the two, which can easily lead to misjudgment of the rate constant.

[0100] (3) Complex interface reaction conditions

[0101] Electrocatalytic and photoelectrocatalytic reaction interfaces usually include electrodes, solutions, and intermediates, and the interactions between these components are complex. Factors such as the electric field, local pH value, and ion concentration on the electrocatalytic interface can affect the reaction kinetics of the intermediates, making it difficult to directly measure the actual rate constants of the intermediate reactions.

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

[0103] The current and potential in electrocatalytic and photoelectrocatalytic 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 relatively stable reaction conditions, and under non-steady-state potential, the concentration and rate constant of the intermediates will be disturbed, which may lead to the inability to accurately fit the decay data.

[0104] (5) Impact of environmental factors

[0105] In the electrocatalytic and photoelectrocatalytic interface environment, the composition of the solution (such as dissolved oxygen, proton concentration, and ionic strength) will affect the generation and decay of intermediates, especially at the gas-liquid-solid three-phase interface, where the gas diffusion rate will also become an influencing factor. The intermediate decay fitting method may not fully consider the influence of these factors, resulting in large errors in the measurement results.

[0106] In view of the above problems, the present invention aims to propose a method that can effectively eliminate the interference with the intermediate reaction rate constant caused by factors such as the complexity of the electrocatalytic and photoelectrocatalytic reaction systems, the high charge transfer rate, the large environmental noise, and the intermediate signals and dynamics being extremely susceptible to environmental interference, and accurately and directly determine the intermediate reaction rate constants in the electrocatalytic and photoelectrocatalytic systems.

[0107] Specifically, the present invention provides a method for determining the intermediate reaction rate constant of an electrocatalytic and photoelectrocatalytic system, see Figure 1 and Figure 2 It is understood that the method may include the following steps:

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

[0109] See also Figure 3 A phase-sensitive detection in-situ electrochemical infrared spectroscopy test system was built, which has the characteristics of low detection limit and strong anti-interference ability. Low detection limit means that the substance can be detected when the content is very low, so the detection sensitivity is high. The anti-interference ability is manifested in the resistance to interference factors of non-reaction processes such as background interference and environmental interference.

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

[0111] The time-resolved infrared spectrometer is equipped with a reaction chamber for electrochemical infrared spectroscopy testing, which is used to complete the electrochemical infrared spectroscopy testing.

[0112] See also Figure 4 Understand the assembly process and final structure of the reaction chamber.

[0113] The reaction chamber is assembled in sequence from a chamber body, a crystal sheet with a metal layer deposited thereon, a gasket and a chamber side plate.

[0114] The cavity body is a rectangular parallelepiped, and its upper surface and one side wall are arranged in a central opening shape. Figure 4The light blue area on the middle cavity body; the cavity body is used to place the electrolyte required for 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 opening area size of the side wall opening of the cavity body to achieve a good sealing and fitting effect with 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 matching the opening area of ​​the cavity side plate, see the area corresponding to the dark gray rectangular frame, the gasket is used to support the crystal sheet, so that in the assembled reaction chamber, the surface of the crystal sheet is exposed through the opening area, and it is ensured to be well sealed without leakage;

[0117] For the assembled reaction chamber, the exposed crystal sheet is used as a working electrode, driven by an external potential, and the working electrode is also used to detect signal output.

[0118] The material of the crystal sheet 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, etc., and there is no specific limitation here.

[0119] See also Figure 4 As shown, the reaction chamber is also provided with a reference electrode and a counter electrode, and the reference electrode and the counter electrode are in contact with the electrolyte. The reference electrode is used to provide a reference value for the potential applied to 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 into the test system, setting the current cycle indicating its change and executing the corresponding test operation, obtaining the test data under the periodic drive of the applied potential corresponding to the current cycle, and changing the set cycle to complete the test operations of multiple 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, and infrared spectral data consisting of infrared test time, wave number corresponding to different infrared test times, and real-time absorbance; the electrochemical data comes from the electrochemical workstation, and the infrared spectral data comes from the time-resolved infrared spectrometer;

[0121] In the embodiment of the present invention, a cycle of change is set for the applied potential of the test system. Under the same set cycle, the applied potential is loaded multiple times according to the cycle, so that the test system completes the corresponding test work under the cycle.

[0122] The setting for any cycle can be set according to the start time, the end time and the number of times the external potential needs to change in this cycle.

[0123] It should be noted that, before setting a current cycle indicating a change of an applied potential for loading to the test system and performing a corresponding test operation to obtain test data under periodic driving of an applied potential corresponding to the current cycle, the method further includes:

[0124] 1) for the current cycle, when no corresponding external potential is loaded, using the time-resolved infrared spectrometer to perform a background test on the reaction system corresponding to the test system;

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

[0126] 2) After completing the background test, 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 an external potential on the reaction system according to the input waveform signal.

[0129] The above steps 2) to 4) are essentially to trigger the corresponding test operation after the background test is completed. Triggering the corresponding test operation is to trigger the electrochemical workstation to apply a periodic external potential corresponding to the current cycle to the test system, that is, the external potential is repeatedly applied according to the current cycle, 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 changes to drive the electrochemical reaction, and synchronously collect electrochemical data during the reaction process, and the time-resolved infrared spectrometer will also output infrared spectrum data after performing time-resolved in-situ infrared spectrum detection.

[0130] The preset electrical signal may be a preset high voltage signal, which is specifically set by a function waveform generator.

[0131] For each set cycle, corresponding test data can be obtained. The test data comes from the electrochemical workstation, which is electrochemical data, including the real-time potential e(t e )、real-time current i(t e ), electrochemical test time t e etc.; the test data on the other hand comes from the time-resolved infrared spectrometer, which is infrared spectrum data, including infrared test time t IR , Different infrared test time t IR The corresponding wave number w and real-time absorbance A(w,t IR ). Among them, any infrared test time t IR There are multiple groups [w, A(w,t IR )]. As mentioned above, in infrared testing, A(w,t IR ) is directly output using the relevant data of the corresponding background test.

[0132] S3, classifying and processing the test data corresponding to each cycle;

[0133] Specifically, the step may include:

[0134] S31, 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 )], which is reflected in the form of two-dimensional data;

[0135] Specifically, for the current cycle, the start and end times of the electrochemical test and infrared test are consistent. In the electrochemical test, periodic tests will be performed based on the current cycle. Depending on the sampling time, there will be multiple electrochemical test times t e , each electrochemical test time t e The corresponding real-time potential e(t e ) and real-time current i(t e ). In infrared testing, there will also be corresponding multiple sampling times, namely infrared test time t IR , each t IR There are multiple groups [w, A(w,t IR )]. Due to the different sampling frequencies of electrochemical test and infrared test, the electrochemical test time te And infrared test time t IR There is no 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 the read data.

[0137] The time interval for data processing can be selected according to the needs to be a time interval between the corresponding start time and the end time in the test data, and there is no specific limitation here.

[0138] S4, converting the test data after classification processing of each period from time dependence to phase dependence, and then obtaining the 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;

[0139] Specifically, the conversion of the test data after the classification processing of each period from time dependence to phase dependence may include the following steps:

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

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

[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 ) are converted into different phase dependent and in, For custom phase, The value range of is [0,2π]; It is selected multiple times, and there is no restriction on the specific value within the value range each time.

[0143] The corresponding conversion formulas include:

[0144]

[0145] Wherein, T represents the actual duration calculated for the cycle.

[0146] Specifically, the step of obtaining infrared spectra corresponding to different phases in a corresponding period and solving the phase difference of the intermediate infrared signal corresponding to the corresponding period may include the following steps:

[0147] ① 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;

[0148] In this step, by By performing infrared spectroscopy analysis, it is possible to determine what kind of intermediates are present, and based on the correspondence between known intermediates and infrared wave numbers, the infrared wave number w0 corresponding to the intermediate can be determined.

[0149] ② From this cycle Select the infrared absorption data of intermediates corresponding to different phases in the data

[0150] ③Calculation and the same phase Phase difference Thus, the phase difference of the intermediate infrared signal corresponding to the period is obtained

[0151] For any set period, a corresponding phase difference can be obtained

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

[0153] This step may 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 data is fitted to obtain the intermediate reaction rate constant; wherein, the preset formula is:

[0155]

[0156] In the above formula, T n For example, T nIndicates the actual duration of the nth cycle of the applied potential change; T n The corresponding phase difference of the intermediate infrared signal; k is the intermediate reaction rate constant.

[0157] For specific data fitting, please refer to the relevant technical understanding, which will not be explained in detail here.

[0158] The process of obtaining the intermediate reaction rate constant by performing a complete test in the embodiment of the present invention can be found in Figure 5 Schematic diagram for understanding.

[0159] In the solution provided by the embodiment of the present invention, by establishing the intermediate signal phase difference Based on the relationship between the applied potential period and the intermediate reaction rate constant, a new method for determining the intermediate reaction rate constant in electrocatalysis and photoelectrocatalysis systems using phase sensitive detection in situ electrochemical infrared spectroscopy (PSD-FTIR) is proposed. This method can effectively eliminate the interference on the intermediate reaction rate constant caused by factors such as the complexity of the electrocatalytic and photoelectrocatalytic reaction system, high charge transfer rate, large environmental noise, and the intermediate signal and kinetics being extremely susceptible to environmental interference, 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, providing a new research approach for studying the problem of intermediate reaction kinetics in electrocatalysis and photoelectrocatalysis systems.

[0160] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0161] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0162] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0163] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for determining the intermediate reaction rate constant of an electrocatalytic and photoelectrocatalytic system, characterized in that: include: Building a test system for phase-sensitive detection of in-situ electrochemical infrared spectroscopy, the test system comprising a time-resolved infrared spectrometer, an electrochemical workstation, a function waveform generator, a trigger controller and a data acquisition and processing device; For the 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 a plurality of 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, and infrared spectral data consisting of infrared test time, wavenumber corresponding to different infrared test times, and real-time absorbance; the electrochemical data comes from the electrochemical workstation, and the infrared spectral data comes from the time-resolved infrared spectrometer; Classify and process the test data corresponding to each cycle respectively; The test data after classification processing of each period are respectively 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 was solved by data fitting.

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 built 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 with a metal layer deposited thereon, a gasket and a chamber side plate; wherein the chamber body is a rectangular parallelepiped, and its upper surface and one side wall are arranged in a central opening shape, and the chamber body is used to place the electrolyte required for the reaction process; the crystal sheet is arranged 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 surface of the crystal sheet is exposed through the opening area, and the sealing is ensured to be good without leakage; 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 also 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 sheet 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 of an applied potential for loading to the test system and performing a corresponding test operation to obtain test data under periodic driving of an applied potential corresponding to the current cycle, the method further includes: For the current cycle, when no corresponding external potential is loaded, using the time-resolved infrared spectrometer to perform a background test on the reaction system corresponding to the test system; 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 a 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 the 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 cycle is converted from time dependence to phase dependence, including: For any cycle, calculate the actual duration of the cycle; 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: Wherein, 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 step of obtaining infrared spectra corresponding to different phases in corresponding periods 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 in the data calculate and the same phase Phase difference Thus, the phase difference of the intermediate infrared signal corresponding to the period is obtained 10. The method for determining the intermediate reaction rate constant of the electrocatalytic and photoelectrocatalytic system according to claim 9, characterized in that: 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: 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 data is fitted 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 corresponding phase difference of the intermediate infrared signal; k is the intermediate reaction rate constant.

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