A transient potential scanning circuit for optical and electrocatalytic reaction detection research

Abstract

This invention discloses a transient potential scanning circuit for the detection and research of photocatalytic and electrocatalytic reactions. It includes a digitally controlled capacitor charging circuit, a capacitor polarity conversion circuit, a capacitor discharge signal conditioning circuit, a programmable gain I / V conversion circuit, and a microcontroller. The host computer outputs the capacitor charging voltage setting command, the capacitor discharge polarity setting command, and the gain setting command to the microcontroller in one go via a serial communication protocol. This controls the microcontroller to precisely execute charging, discharging, and gain control operations. The current signal of the working electrode of the electrochemical cell can be effectively amplified through the programmable gain I / V conversion circuit. The advantages are that it improves the accuracy of the capacitor charging voltage setting, reduces the difficulty of detecting weak current signals from the working electrode of the electrochemical cell, simplifies the detection process, and reduces the likelihood of misoperation.

Description

Technical Field

[0001] This invention relates to transient potential scanning circuits, and more particularly to a transient potential scanning circuit for the detection and research of photocatalytic and electrocatalytic reactions. Background Technology

[0002] In modern society, catalytic reaction detection technology has become a key factor driving energy conversion and industrial development. As the cornerstone of the chemical industry, catalytic reactions have their detection technologies applied across many important fields, including petrochemicals, environmental monitoring, and energy. Photocatalytic and electrocatalytic reaction technologies, as emerging green catalytic technologies, have shown great potential in energy conversion and environmental remediation. In photocatalytic and electrocatalytic reaction research, continuously optimizing and improving catalytic reaction detection methods to obtain information on changes in the electric double layer interface of catalytic reactions provides crucial technical support for catalyst performance testing and the optimization of catalytic reaction conditions.

[0003] In the study of photocatalytic and electrocatalytic reaction mechanisms, traditional in-situ characterization techniques such as in-situ infrared spectroscopy, in-situ Raman spectroscopy, and in-situ synchrotron radiation are widely used due to their rapid testing and time-series recording capabilities. These techniques can reveal changes in catalyst surface state, reaction intermediates, active site structure, and the dynamic evolution of chemical bonds, thereby providing a deeper understanding of catalyst behavior under operating conditions. However, these techniques are limited by strict experimental conditions, high equipment costs, complex operation, and large detection space requirements, which restricts their widespread application. While microscopy detection techniques have fewer experimental restrictions, are simpler to operate, and can perform real-time detection, they also suffer from high costs.

[0004] Electrochemical testing also has the potential to study catalytic reaction mechanisms under time-series conditions. By analyzing current, voltage, and other information within the electrochemical cell system, it can provide insights into charge separation and transfer rates during photocatalytic and electrocatalytic reactions, thereby revealing the behavior of catalysts under actual operating conditions. However, existing electrochemical research methods, such as polarization curves and cyclic voltammetry, tend to mask useful information at high scan rates, while AC impedance methods have long testing times. Therefore, transient potential scanning circuits with dynamic real-time detection capabilities are crucial for advancing the electrochemical detection of photocatalytic and electrocatalytic reactions.

[0005] Reference 1, “K. Qin, H. Yu, W. Zhu, Y. Zhou, Z. Guo, Q. Shao, Y. Wu, X. Wang, Y. Li, Y. Ji, F. Liao, Y. Liu, Z. Kang, M. Shao, 1D Monoclinic IrxRu1-xO2 Solid Solution with Ru-Enhanced Electrocatalytic Activity for Acidic Oxygen EvolutionReaction. Adv. Funct. Mater. 2024, 2402226,” discloses a transient detection technique for studying the charge distribution dynamics on catalyst surfaces. It investigates the charge response of catalysts at different potentials, thereby revealing the behavior of their active sites in electrochemical reactions. This transient detection technique first charges a fixed capacitor to a certain potential (U0), and then rapidly connects the charged capacitor to the electrochemical system to simulate the response of the electrocatalyst at that potential. Its transient potential scan (TPS) circuit is as follows: Figure 1 As shown, the current change in this transient potential scanning circuit reflects the charge distribution on the catalyst surface and the dynamic process of the redox reaction. In the RC circuit, the relationship between current (i) and resistance (R), capacitance (C), and applied voltage (U) can be described by the following formula: Where τ = RC is the time constant of the circuit, and e is the base of the natural logarithm. By measuring and analyzing the change of current over time at different potentials, researchers can obtain the current of the catalyst at different voltages to analyze the surface state of the catalyst at different voltages. Thus, with the increase of the applied voltage U0, the peak current of the above transient detection technique also increases. By integrating the current within a short time (0.01 milliseconds) to obtain the charge (Q), the influencing factors of the catalyst active sites can be obtained by comparing the catalyst charge.

[0006] Reference 2, "Jiaxuan W, Jiacheng L, Zenan L, et al. In-situ study of the hydrogen peroxide photoproduction in seawater on carbon dot-based metal-free catalyst under operation condition[J]. Nano Research, 2024, 17(7): 5956-5964," also mentions transient potential scanning technology, used to analyze and study the mechanism of photocatalytic H2O2 generation in water and seawater. Its transient potential scanning circuit can be simply described as a capacitor with an adjustable positive or negative voltage, discharging to the working electrode (WE). The schematic diagram of the transient potential scanning circuit for the TPS test under dark conditions is shown in Figure 2(a), and the corresponding equivalent circuit is shown in Figure 2(b). The schematic diagram of the TPS test under illumination conditions is shown in Figure 2(c), and the corresponding equivalent circuit is shown in Figure 2(d). The schematic diagram of the TPS test under -0.5V illumination conditions is shown in Figure 2(e), and the corresponding equivalent circuit is shown in Figure 2(f). In Figures 2(b), 2(d), and 2(f), C0, C1, C2, C3, and C4 represent the test capacitance of 470 μF, the catalyst space charge region capacitance, the catalyst surface state capacitance and its pseudo-capacitance, the interface bilayer capacitance, and the solid interface capacitance of the modified electrode, respectively. R1 is derived from the solution resistance, and R2 is the Faraday resistance corresponding to the reaction. As shown in Figures 2(a) and 2(b), C0 will discharge when there is no light illuminating the transient potential scanning circuit. As shown in Figures 2(c) and 2(d), during photocatalysis, C0 and C1 discharge when the transient potential scanning circuit is irradiated. Figure 2(e) and 2(f) As shown, C0 and C1 discharge together after illumination. For n-type semiconductors, C0 and C1 are in the same direction when a negative voltage is applied, and in opposite directions when a positive voltage is applied. After the capacitor discharges, the charging current decreases exponentially until the charge in the transient potential scanning circuit reaches equilibrium. The charge consumption time (τ) is related to the capacitance and resistance (τ = RC). As the reaction proceeds, adsorption occurs on the electrode surface, the dielectric increases, the capacitance increases, and the decay time becomes longer. The current decay curve represents the generation or consumption of charge at the charge catalyst interface.

[0007] The transient potential scanning circuits mentioned in the two aforementioned studies on photocatalytic reactions can be understood as charging a capacitor and then discharging it into an electrochemical cell. By changing the capacitor's charging voltage or the illumination of the electrochemical cell, the voltage and current across the electrodes are analyzed, thereby monitoring the dynamic charge distribution during the photocatalytic reaction in real time. However, in the transient potential scanning circuits used in these studies for photocatalytic reaction detection, the positive and negative voltages applied to the capacitor in the electrochemical cell are controlled by a digital potentiometer knob. This voltage adjustment is not precise enough, resulting in large errors in the capacitor charging voltage setting and consequently, low accuracy in the detection results. Furthermore, the electrochemical signals, such as current signals, at the working electrode in the electrochemical cell are typically only a few milliamps or tens of milliamps, making direct detection difficult. Additionally, the selection of the capacitor's forward and reverse charging direction in the transient potential scanning circuit is controlled manually using buttons on the circuit board, requiring repeated switching. This makes the detection process complex and prone to accidental button presses and reagent contamination of the circuit panel. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a transient potential scanning circuit for the detection and research of photocatalytic reactions that can improve the accuracy of capacitor charging voltage setting, reduce the difficulty of detecting weak current signals of working electrodes of electrochemical cells, simplify the detection operation process, and reduce the likelihood of misoperation.

[0009] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a transient potential scanning circuit for photocatalytic and electrocatalytic reaction detection research, including a digitally controlled capacitor charging circuit, a capacitor polarity conversion circuit, a capacitor discharge signal conditioning circuit, a programmable gain I / V conversion circuit, and a microcontroller. The capacitor polarity conversion circuit includes a first capacitor. The microcontroller can communicate with a host computer via a serial communication protocol, and receive capacitor charging voltage setting instructions, capacitor discharge polarity setting instructions, and gain setting instructions set by the host computer according to the detection operation requirements of the electrochemical cell. After receiving the capacitor charging voltage setting instructions, capacitor discharge polarity setting instructions, and gain setting instructions, the microcontroller first outputs the corresponding voltage control signal to the digitally controlled capacitor charging circuit according to the capacitor charging voltage setting instructions, so that the digitally controlled capacitor charging circuit outputs... A voltage signal equal to the set value of the capacitor charging voltage is sent to the capacitor polarity conversion circuit. Then, according to the capacitor discharge polarity setting command, a polarity control signal is output to control the charging and discharge polarity of the first capacitor, ensuring that the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit is equal to the voltage required in the actual experiment. The capacitor discharge signal conditioning circuit follows the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit and generates a corresponding voltage signal output. When the capacitor polarity conversion circuit applies voltage to the counter electrode of the electrochemical cell, the microprocessor outputs a corresponding gain control signal according to the gain setting command to control the programmable gain I / V conversion circuit to convert the current signal of the working electrode of the electrochemical cell into a voltage signal output according to the set gain.

[0010] Compared with existing technologies, the advantages of this invention lie in that it sets capacitor charging voltage, capacitor discharge polarity, and gain settings at the host computer according to the detection operation requirements of the electrochemical cell, and outputs these settings to the microcontroller in one go via serial communication protocol. This controls the microcontroller to accurately execute charging, discharging, and gain control operations, eliminating the need for manual setting and adjustment of the capacitor charging voltage or multiple manual button operations, greatly simplifying the testing process and preventing accidental button presses. Furthermore, the current signal from the working electrode of the electrochemical cell can be effectively amplified by the programmable gain I / V conversion circuit, thereby expanding the detection range of the current signal from the working electrode and facilitating subsequent data acquisition and analysis. Therefore, this invention improves the accuracy of capacitor charging voltage settings, reduces the difficulty of detecting weak current signals from the working electrode of the electrochemical cell, and simplifies the detection process, reducing the likelihood of misoperation.

[0011] Furthermore, the numerically controlled capacitor charging circuit has an input terminal and an output terminal; the capacitor polarity conversion circuit has an input terminal, an output terminal, and two control terminals, referred to as the first control terminal and the second control terminal, respectively; the capacitor discharge signal conditioning circuit has an input terminal and an output terminal; the programmable gain I / V conversion circuit has an input terminal, an output terminal, and two control terminals, referred to as the first control terminal and the second control terminal, respectively; the microcontroller has an input terminal and five output terminals, referred to as the first output terminal, the second output terminal, the third output terminal, the fourth output terminal, and the fifth output terminal, respectively. The input terminal of the microcontroller is used to connect with the host computer via a serial communication protocol; the first output terminal of the microcontroller is used to output a voltage control signal; the second and third output terminals of the microcontroller are used to output polarity control signals; and the fourth and fifth output terminals of the microcontroller are used to output gain control signals. The input terminal of the capacitor charging circuit is connected to the first output terminal of the microcontroller. The output terminal of the numerically controlled capacitor charging circuit is used to output a voltage signal with a magnitude equal to the set value of the capacitor charging voltage. The output terminal of the numerically controlled capacitor charging circuit is connected to the input terminal of the capacitor polarity conversion circuit. The first control terminal of the capacitor polarity conversion circuit is connected to the second output terminal of the microcontroller. The second control terminal of the capacitor polarity conversion circuit is connected to the third output terminal of the microcontroller. The output terminal of the capacitor polarity conversion circuit is connected to the counter electrode of the electrochemical cell. The input terminal of the capacitor discharge signal conditioning circuit is connected to the counter electrode of the electrochemical cell. The input terminal of the programmable gain I / V conversion circuit is connected to the working electrode of the electrochemical cell. The first control terminal of the programmable gain I / V conversion circuit is connected to the fourth output terminal of the microcontroller. The second control terminal of the programmable gain I / V conversion circuit is connected to the fifth output terminal of the microcontroller.

[0012] Furthermore, the numerically controlled capacitor charging circuit includes a first resistor, a second resistor, a third resistor, a first operational amplifier, and a second operational amplifier. Both the first and second operational amplifiers have a non-inverting input terminal, an inverting input terminal, and an output terminal. One end of the first resistor is connected to the inverting input terminal of the first operational amplifier, and the non-inverting input terminal of the first operational amplifier is the input terminal of the numerically controlled capacitor charging circuit. The other end of the first resistor, the output terminal of the first operational amplifier, and the non-inverting input terminal of the second operational amplifier are connected. The inverting input terminal of the second operational amplifier, one end of the second resistor, and one end of the third resistor are connected. The other end of the third resistor is grounded. The other end of the second resistor is connected to the output terminal of the second operational amplifier, and this connection terminal is the output terminal of the numerically controlled capacitor charging circuit.

[0013] Furthermore, the capacitor polarity conversion circuit also includes a fourth resistor and two relays. Each relay has two normally open terminals, two normally closed terminals, two common terminals, and a control coil terminal. The two normally open terminals are referred to as the first normally open terminal and the second normally open terminal, the two normally closed terminals as the first normally closed terminal and the second normally closed terminal, and the two common terminals as the first common terminal and the second common terminal. The control coil terminal of the relay is used to receive a control signal. When the control signal received at the control coil terminal of the relay is high, the first normally open terminal is connected to the first common terminal, the second normally open terminal is connected to the second common terminal, the first normally closed terminal is disconnected from the first common terminal, and the second normally closed terminal is connected to the second common terminal. When the control signal received at the control coil terminal of the relay is low, the first normally open terminal is disconnected from the first common terminal, the second normally open terminal is disconnected from the second common terminal, the first normally closed terminal is connected to the first common terminal, and the second normally closed terminal is connected to the second common terminal. The two relays are referred to as the first relay and the second relay. The second relay; one end of the fourth resistor is the input terminal of the capacitor polarity conversion circuit, the other end of the fourth resistor is connected to the first normally closed terminal of the first relay, the second normally closed terminal of the first relay is grounded, one end of the first capacitor is connected to the first common terminal of the first relay, the other end of the first capacitor is connected to the second common terminal of the first relay, the first normally open terminal of the first relay is connected to the first common terminal of the second relay, the second normally open terminal of the first relay is connected to the second common terminal of the second relay, the first normally closed terminal of the second relay is connected to its second normally open terminal, and its connection terminal is the output terminal of the capacitor polarity conversion circuit, both the first normally open terminal and the second normally closed terminal of the second relay are grounded, the control coil terminal of the first relay is the first control terminal of the capacitor polarity conversion circuit, and the control coil terminal of the second relay is the second control terminal of the capacitor polarity conversion circuit.

[0014] Furthermore, the capacitor discharge signal conditioning circuit includes a fifth resistor and a third operational amplifier. The third operational amplifier has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the third operational amplifier is the input terminal of the capacitor discharge signal conditioning circuit. The inverting input terminal of the third operational amplifier is connected to one end of the fifth resistor, and the output terminal of the third operational amplifier is connected to the other end of the fifth resistor, with the connection terminal serving as the output terminal of the capacitor discharge signal conditioning circuit.

[0015] Furthermore, the programmable gain I / V conversion circuit includes a fourth operational amplifier, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, and a 4-to-1 analog switch. The 4-to-1 analog switch has four selection terminals, one common terminal, and two control terminals. The two control terminals of the 4-to-1 analog switch are respectively used to receive selection signals. Under the control of the selection signals received by the two control terminals, one of the four selection terminals of the 4-to-1 analog switch is connected to its common terminal, while the other three are disconnected from their common terminal. The four selection terminals of the 4-to-1 analog switch are respectively referred to as its first selection terminal, second selection terminal, third selection terminal, and fourth selection terminal, and the two control terminals of the 4-to-1 analog switch are respectively referred to as its first control terminal and second control terminal. When the selection signals received by the first control terminal and second control terminal of the 4-to-1 analog switch are both low level, its first selection terminal is connected to... Its common terminal is on, while the second, third, and fourth selection terminals are all off from their common terminal; when the selection signal connected to the first control terminal of the four-to-one analog switch is low and the selection signal connected to the second control terminal is high, its second selection terminal is on with its common terminal, while the first, third, and fourth selection terminals are all off from their common terminal; when the selection signal connected to the first control terminal of the four-to-one analog switch is high and the selection signal connected to the second control terminal is low, its third selection terminal is on with its common terminal, while the first, second, and fourth selection terminals are all off from their common terminal; when the selection signals connected to both the first and second control terminals of the four-to-one analog switch are high, its fourth selection terminal is on with its common terminal, while the first, second, and third selection terminals are all off from their common terminal; the fourth operational amplifier has a non-inverting input terminal, an inverting input terminal, and an output terminal;The non-inverting input terminal of the fourth operational amplifier is grounded. The inverting input terminal of the fourth operational amplifier, one end of the sixth resistor, one end of the second capacitor, one end of the seventh resistor, one end of the third capacitor, one end of the eighth resistor, one end of the fourth capacitor, one end of the ninth resistor, and one end of the fifth capacitor are connected, and this connection is the input terminal of the programmable gain I / V conversion circuit. The other end of the sixth resistor and the other end of the second capacitor are connected to the first selection terminal of the four-to-one analog switch. The other end of the seventh resistor and the other end of the third capacitor are connected to the four-to-one analog switch. The second selection terminal is connected to the fourth capacitor, the other end of the eighth resistor and the other end of the fourth capacitor are connected to the third selection terminal of the four-to-one analog switch, the other end of the ninth resistor and the other end of the fifth capacitor are connected to the fourth selection terminal of the four-to-one analog switch, the common terminal of the four-to-one analog switch is connected to the output terminal of the fourth operational amplifier, and its connection terminal is the output terminal of the programmable gain I / V conversion circuit. The first control terminal of the four-to-one analog switch is the first control terminal of the programmable gain I / V conversion circuit; the second control terminal of the four-to-one analog switch is the second control terminal of the programmable gain I / V conversion circuit. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the transient potential scan (TPS) disclosed in Reference 1;

[0017] Figure 2(a) is a schematic diagram of the transient potential scanning circuit disclosed in Reference 2 under TPS test conditions in the dark.

[0018] Figure 2(b) is the equivalent circuit diagram of Figure 2(a);

[0019] Figure 2(c) is a schematic diagram of the transient potential scanning circuit disclosed in Reference 2 under illumination conditions for TPS test;

[0020] Figure 2(d) is the equivalent circuit diagram of Figure 2(c);

[0021] Figure 2(e) is a schematic diagram of the transient potential scanning circuit disclosed in Reference 2 under TPS test conditions of -0.5V illumination;

[0022] Figure 2(f) is the equivalent circuit diagram of Figure 2(e);

[0023] Figure 3 This is a structural diagram of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention.

[0024] Figure 4(a) is a circuit diagram of the digitally controlled capacitor charging circuit of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention;

[0025] Figure 4(b) is a circuit diagram of the capacitor polarity conversion circuit of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention;

[0026] Figure 4(c) is a circuit diagram of the capacitor discharge signal conditioning circuit of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention;

[0027] Figure 4(d) is a circuit diagram of the programmable gain I / V conversion circuit of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention;

[0028] Figure 5(a) shows the transient potential scanning circuit of the present invention for photocatalytic reaction detection research, with a 10kΩ resistor connected between the counter electrode and the working electrode of the electrochemical cell. Based on the capacitor charging voltage value setting command and the capacitor discharge polarity setting command, the microcontroller outputs the voltage signal V at the output terminal of the capacitor discharge signal conditioning circuit when the voltage signal applied to the counter electrode of the electrochemical cell is +1V and the gain is set to 10K according to the gain setting command. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 Waveform diagram;

[0029] Figure 5(b) shows the transient potential scanning circuit of the present invention for photocatalytic reaction detection research, with a 10kΩ resistor connected between the counter electrode and the working electrode of the electrochemical cell. Based on the capacitor charging voltage value setting command and the capacitor discharge polarity setting command, the microcontroller outputs the voltage signal V at the output terminal of the capacitor discharge signal conditioning circuit when the voltage signal applied to the counter electrode of the electrochemical cell is +1V and the gain is set to 100K according to the gain setting command. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 Waveform diagram;

[0030] Figure 5(c) shows the transient potential scanning circuit of the present invention for photocatalytic reaction detection research, with a 10kΩ resistor connected between the counter electrode and the working electrode of the electrochemical cell. Based on the capacitor charging voltage value setting command and the capacitor discharge polarity setting command, the microcontroller outputs the voltage signal V at the output terminal of the capacitor discharge signal conditioning circuit when the voltage signal applied to the counter electrode of the electrochemical cell is -1V and the gain is set to 10K according to the gain setting command. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 Waveform diagram;

[0031] Figure 5(d) shows the transient potential scanning circuit of this invention for photocatalytic reaction detection research, where a 10kΩ resistor is connected between the counter electrode and the working electrode of the electrochemical cell. Based on the capacitor charging voltage value setting command and the capacitor discharge polarity setting command, the microcontroller outputs a voltage signal V at the output terminal of the capacitor discharge signal conditioning circuit when the voltage signal applied to the counter electrode of the electrochemical cell is -1V and the gain is set to 100K according to the gain setting command. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 Waveform diagram;

[0032] Figure 6(a) shows a series circuit with a 10kΩ resistor and a 0.47uF capacitor connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit of this invention, for the detection of photocatalytic and electrocatalytic reactions, sets the voltage signal applied to the counter electrode of the electrochemical cell to +1V and the gain to 10K according to the gain setting instruction, based on the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction. The voltage signal V output from the capacitor discharge signal conditioning circuit is shown in the figure. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 Waveform diagram;

[0033] Figure 6(b) shows a series circuit with a 10kΩ resistor and a 0.47uF capacitor connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit of this invention, for the detection of photocatalytic and electrocatalytic reactions, sets the voltage signal applied to the counter electrode of the electrochemical cell to +1V and the gain to 100K according to the gain setting instruction, based on the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction. The voltage signal V output from the capacitor discharge signal conditioning circuit is shown in the figure. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 Waveform diagram;

[0034] Figure 6(c) shows a series circuit with a 10kΩ resistor and a 0.47uF capacitor connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit of this invention, for the detection of photocatalytic and electrocatalytic reactions, sets the voltage signal applied to the counter electrode of the electrochemical cell to -1V and the gain to 10K according to the gain setting command, based on the capacitor charging voltage value setting command and the capacitor discharge polarity setting command. The output voltage signal V from the capacitor discharge signal conditioning circuit is shown in the figure. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit.o2 Waveform diagram;

[0035] Figure 6(d) shows a series circuit with a 10kΩ resistor and a 0.47uF capacitor connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit of this invention, for the detection of photocatalytic and electrocatalytic reactions, sets the voltage signal applied to the counter electrode of the electrochemical cell to -1V and the gain to 100K according to the gain setting instruction, based on the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction. The output voltage signal V from the capacitor discharge signal conditioning circuit is shown in the figure. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform diagram. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0037] Example 1: As Figure 3 As shown, a transient potential scanning circuit for photocatalytic reaction detection research includes a digitally controlled capacitor charging circuit, a capacitor polarity conversion circuit, a capacitor discharge signal conditioning circuit, a programmable gain I / V conversion circuit, and a microcontroller. The capacitor polarity conversion circuit includes a first capacitor C1. The microcontroller can communicate with a host computer via a serial communication protocol, receiving capacitor charging voltage setting instructions, capacitor discharge polarity setting instructions, and gain setting instructions set by the host computer according to the detection operation requirements of the electrochemical cell. After receiving the capacitor charging voltage setting instructions, capacitor discharge polarity setting instructions, and gain setting instructions, the microcontroller first outputs the corresponding voltage control signal to the digitally controlled capacitor charging circuit according to the capacitor charging voltage setting instructions, so that the digitally controlled capacitor charging circuit outputs a voltage control signal. A voltage signal equal to the set value of the capacitor charging voltage is sent to the capacitor polarity conversion circuit. Then, according to the capacitor discharge polarity setting command, a polarity control signal is output to control the charging and discharge polarity of the first capacitor C1, so that the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit is equal to the voltage required by the actual experiment. The capacitor discharge signal conditioning circuit is used to follow the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit and generate a corresponding voltage signal output. When the capacitor polarity conversion circuit applies voltage to the counter electrode of the electrochemical cell, the microprocessor outputs a corresponding gain control signal according to the gain setting command to control the programmable gain I / V conversion circuit to convert the current signal of the working electrode of the electrochemical cell into a voltage signal output according to the set gain.

[0038] In this embodiment, the numerically controlled capacitor charging circuit has an input terminal and an output terminal; the capacitor polarity conversion circuit has an input terminal, an output terminal, and two control terminals, referred to as the first control terminal and the second control terminal, respectively; the capacitor discharge signal conditioning circuit has an input terminal and an output terminal; the programmable gain I / V conversion circuit has an input terminal, an output terminal, and two control terminals, referred to as the first control terminal and the second control terminal, respectively; the microcontroller has an input terminal and five output terminals, referred to as the first output terminal, the second output terminal, the third output terminal, the fourth output terminal, and the fifth output terminal, respectively. The input terminal of the microcontroller is used to connect with the host computer via a serial communication protocol; the first output terminal of the microcontroller is used to output a voltage control signal; the second and third output terminals of the microcontroller are used to output a polarity control signal; and the fourth and fifth output terminals of the microcontroller are used to output an increase signal. The input terminal of the digitally controlled capacitor charging circuit is connected to the first output terminal of the microcontroller. The output terminal of the digitally controlled capacitor charging circuit is used to output a voltage signal with a magnitude equal to the set value of the capacitor charging voltage. The output terminal of the digitally controlled capacitor charging circuit is connected to the input terminal of the capacitor polarity conversion circuit. The first control terminal of the capacitor polarity conversion circuit is connected to the second output terminal of the microcontroller. The second control terminal of the capacitor polarity conversion circuit is connected to the third output terminal of the microcontroller. The output terminal of the capacitor polarity conversion circuit is connected to the counter electrode of the electrochemical cell. The input terminal of the capacitor discharge signal conditioning circuit is connected to the counter electrode of the electrochemical cell. The input terminal of the programmable gain I / V conversion circuit is connected to the working electrode of the electrochemical cell. The first control terminal of the programmable gain I / V conversion circuit is connected to the fourth output terminal of the microcontroller. The second control terminal of the programmable gain I / V conversion circuit is connected to the fifth output terminal of the microcontroller.

[0039] In this embodiment, the capacitor discharge signal conditioning circuit follows the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit and generates a corresponding voltage signal, which is output through its output terminal. The programmable gain I / V conversion circuit converts the current signal of the working electrode of the electrochemical cell into a voltage signal under the control of the microcontroller. The voltage signal output by the capacitor discharge signal conditioning circuit and the voltage signal output by the programmable gain I / V conversion circuit are the transient potential scanning signals.

[0040] In this embodiment, by setting capacitor charging voltage, capacitor discharge polarity, and gain at the host computer according to the detection operation requirements of the electrochemical cell, and outputting these commands to the microcontroller in one go via serial communication protocol, the microcontroller can accurately execute charging, discharging, and gain control operations. This eliminates the need for manual setting and adjustment of the capacitor charging voltage and multiple manual button presses, greatly simplifying the testing process and preventing accidental button presses. Furthermore, the current signal from the working electrode of the electrochemical cell can be effectively amplified by the programmable gain I / V conversion circuit, thereby expanding the detection range of the working electrode's current signal, facilitating subsequent data acquisition and analysis, and reducing the difficulty of detecting weak current signals from the working electrode.

[0041] Example 2: This example is basically the same as Example 1, except that: In this example, as shown in Figure 4(a), the digitally controlled capacitor charging circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a first operational amplifier A1, and a second operational amplifier A2. Both the first operational amplifier A1 and the second operational amplifier A2 have a non-inverting input terminal, an inverting input terminal, and an output terminal. One end of the first resistor R1 is connected to the inverting input terminal of the first operational amplifier A1. The non-inverting input terminal of the first operational amplifier A1 is the input terminal of the digitally controlled capacitor charging circuit. The other end of the first resistor R1, the output terminal of the first operational amplifier A1, and the non-inverting input terminal of the second operational amplifier A2 are connected. The inverting input terminal of the second operational amplifier A2, one end of the second resistor R2, and one end of the third resistor R3 are connected. The other end of the third resistor R3 is grounded. The other end of the second resistor R2 is connected to the output terminal of the second operational amplifier A2, and its connection terminal is the output terminal of the digitally controlled capacitor charging circuit.

[0042] In the numerically controlled capacitor charging circuit of this embodiment, the first resistor R1 and the first operational amplifier A1 constitute a follower circuit. The first resistor R1 serves as a current-limiting resistor to protect the first operational amplifier A1 from damage caused by excessive input current. The second resistor R2, the third resistor R3, and the second operational amplifier A2 constitute a non-inverting amplifier circuit. The second resistor R2 and the third resistor R3 are used to set the amplification ratio of the second operational amplifier A2. When the microcontroller sets the command according to the received capacitor charging voltage value, it outputs the corresponding capacitor charging voltage to the input terminal of the numerically controlled capacitor charging circuit. The first operational amplifier A1 automatically tracks the capacitor charging voltage to avoid interference between digital and analog circuits, and outputs the corresponding voltage signal to the non-inverting output terminal of the second operational amplifier A2 through its output terminal. The second operational amplifier A2 amplifies the voltage signal to obtain the corresponding voltage signal, which is then output through its output terminal.

[0043] Example 3: This example is basically the same as Example 1, except that, as shown in Figure 4(b), the capacitor polarity conversion circuit further includes a fourth resistor R4 and two relays. Each relay has two normally open terminals, two normally closed terminals, two common terminals, and a control coil terminal. The two normally open terminals are referred to as the first normally open terminal and the second normally open terminal, the two normally closed terminals as the first normally closed terminal and the second normally closed terminal, and the two common terminals as the first common terminal and the second common terminal. The control coil terminal of the relay is used to connect to a control signal. When the control signal connected to the control coil terminal of the relay is high, the first normally open terminal is connected to the first common terminal, the second normally open terminal is connected to the second common terminal, the first normally closed terminal is disconnected from the first common terminal, and the second normally closed terminal is disconnected from the second common terminal. When the control signal connected to the control coil terminal of the relay is low, the first normally open terminal is disconnected from the first common terminal, the second normally open terminal is disconnected from the second common terminal, the first normally closed terminal is connected to the first common terminal, and the second normally closed terminal is connected to the second common terminal. The second common terminal is on; the two relays are referred to as the first relay U1 and the second relay U2, respectively; one end of the fourth resistor R4 is the input terminal of the capacitor polarity conversion circuit, and the other end of the fourth resistor R4 is connected to the first normally closed terminal of the first relay U1. The second normally closed terminal of the first relay U1 is grounded. One end of the first capacitor C1 is connected to the first common terminal of the first relay U1, and the other end of the first capacitor C1 is connected to the second common terminal of the first relay U1. The first normally open terminal of the first relay U1 is connected to the first common terminal of the second relay U2, and the second normally open terminal of the first relay U1 is connected to the second common terminal of the second relay U2. The first normally closed terminal of the second relay U2 is connected to its second normally open terminal, and its connection terminal is the output terminal of the capacitor polarity conversion circuit. Both the first normally open terminal and the second normally closed terminal of the second relay U2 are grounded. The control coil terminal of the first relay U1 is the first control terminal of the capacitor polarity conversion circuit, and the control coil terminal of the second relay U2 is the second control terminal of the capacitor polarity conversion circuit.

[0044] In the capacitor polarity conversion circuit of this embodiment, the fourth resistor R4 acts as a current-limiting resistor to limit the current flowing into the first relay U1, so as to prevent the current flowing into the first relay U1 from being too large and causing damage to the first relay U1.

[0045] When the second output terminal of the microprocessor outputs a low level, and the third output terminal outputs a high or low level, the first normally open terminal of the first relay U1 is cut off from the first common terminal of the first relay U1, the second normally open terminal of the first relay U1 is cut off from the second common terminal of the first relay U1, the first normally closed terminal of the first relay U1 is connected to the first common terminal of the first relay U1, and the second normally closed terminal of the first relay U1 is connected to the second common terminal of the first relay U1. At this time, the first capacitor C1 and the fourth resistor R4 are connected to form a charging path. The voltage signal connected to the input terminal of the capacitor polarity conversion circuit charges the first capacitor C1, so that the first capacitor C1 is charged to the set capacitor charging voltage. Since when the second output terminal of the microprocessor outputs a low level, the two ends of the first capacitor C1 are cut off from the first normally open terminal, the second normally open terminal, the first normally closed terminal, the second normally closed terminal, the first common terminal, and the second common terminal of the second relay U2. The first capacitor C1 cannot form a discharge path with the counter electrode of the electrochemical cell. Therefore, the first capacitor C1 will not discharge to the counter electrode of the electrochemical cell.

[0046] When the second output terminal of the microprocessor outputs a high level and the third output terminal outputs a low level, the first normally open terminal of the first relay U1 is connected to the first common terminal of the first relay U1, and the second normally open terminal of the first relay U1 is connected to the second common terminal of the first relay U1. At this time, the first normally closed terminal of the first relay U1 is cut off from the first common terminal of the first relay U1, and the second normally closed terminal of the first relay U1 is cut off from the second common terminal of the first relay U1. The first normally open terminal of the second relay U2 is cut off from the first common terminal of the second relay U2, and the second normally open terminal of the second relay U2 is cut off from the second common terminal of the second relay U2. The first normally closed terminal of the second relay U2 and the first common terminal of the second relay U2 are connected, and the second normally closed terminal of the second relay U2 and the second common terminal of the second relay U2 are connected. At this time, the first capacitor C1 and the fourth resistor R4 cannot form a charging path. The first capacitor C1 and the counter electrode of the electrochemical cell form a discharging path. The first capacitor C1 discharges to the counter electrode of the electrochemical cell, and the voltage applied to the electrochemical counter electrode is a negative voltage.

[0047] When the second output terminal and the third output terminal of the microprocessor output a high level, the first normally open terminal of the first relay U1 is connected to the first common terminal of the first relay U1, and the second normally open terminal of the first relay U1 is connected to the second common terminal of the first relay U1. At this time, the first normally closed terminal of the first relay U1 is cut off from the first common terminal of the first relay U1, and the second normally closed terminal of the first relay U1 is cut off from the second common terminal of the first relay U1. The first normally open terminal of the second relay U2 is connected to the first common terminal of the second relay U2, and the second normally open terminal of the second relay U2 is connected to the second common terminal of the second relay U2. The first normally closed terminal of the second relay U2 and the first common terminal of the second relay U2 are cut off, and the second normally closed terminal of the second relay U2 and the second common terminal of the second relay U2 are cut off. At this time, the first capacitor C1 and the fourth resistor R4 cannot form a charging path. The first capacitor C1 and the counter electrode of the electrochemical cell form a discharging path. The first capacitor C1 discharges to the counter electrode of the electrochemical cell, and the voltage applied to the counter electrode of the electrochemical cell is a positive voltage.

[0048] Therefore, by setting the high and low levels of the second and third output terminals of the microprocessor according to the capacitor discharge polarity setting instruction, the microprocessor can control the charging and discharge polarity of the first capacitor C1, so that the voltage applied by the first capacitor C1 to the counter electrode of the electrochemical cell is equal to the voltage required by the actual experiment.

[0049] Example 4: This example is basically the same as Example 1, except that: In this example, as shown in Figure 4(c), the capacitor discharge signal conditioning circuit includes a fifth resistor R5 and a third operational amplifier A3. The third operational amplifier A3 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the third operational amplifier A3 is the input terminal of the capacitor discharge signal conditioning circuit. The inverting input terminal of the third operational amplifier A3 is connected to one end of the fifth resistor R5. The output terminal of the third operational amplifier A3 is connected to the other end of the fifth resistor R5, and its connection terminal is the output terminal of the capacitor discharge signal conditioning circuit.

[0050] In the capacitor discharge signal conditioning circuit of this embodiment, the fifth resistor R5 is used as a current limiting resistor to limit the current flowing into the third operational amplifier A3, so as to avoid the third operational amplifier A3 being damaged due to excessive current. The third operational amplifier A3 follows the potential change on the counter electrode of the electrochemical cell and outputs the following voltage signal through its output terminal.

[0051] Example 5: This example is basically the same as Example 1, except that: In this example, as shown in Figure 4(d), the programmable gain I / V conversion circuit includes a fourth operational amplifier A4, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, and a four-to-one analog switch S1; the four-to-one analog switch S1 has four selection terminals, one common terminal, and two control terminals. The two control terminals of the four-to-one analog switch S1 are respectively used to receive selection signals. Under the control of the selection signals received by the two control terminals, one of the four selection terminals of the four-to-one analog switch S1 is turned on with its common terminal, while the other three are turned off with its common terminal. The four selection terminals of the four-to-one analog switch S1 are respectively called its first selection terminal, second selection terminal, third selection terminal, and fourth selection terminal, and the two control terminals of the four-to-one analog switch S1 are respectively called its first control terminal and second control terminal; when the first control terminal and the second control terminal of the four-to-one analog switch S1 are connected, the four-to-one analog switch S1 is connected. When all selection signals connected to the control terminal are low, the first selection terminal is connected to its common terminal, while the second, third, and fourth selection terminals are all disconnected from their common terminal. When the selection signal connected to the first control terminal of the four-to-one analog switch S1 is low and the selection signal connected to the second control terminal is high, the second selection terminal is connected to its common terminal, while the first, third, and fourth selection terminals are all disconnected from their common terminal. When the selection signal connected to the first control terminal of the four-to-one analog switch S1 is high and the selection signal connected to the second control terminal is low, the third selection terminal is connected to its common terminal, while the first, second, and fourth selection terminals are all disconnected from their common terminal. When both the selection signals connected to the first and second control terminals of the four-to-one analog switch S1 are high, the fourth selection terminal is connected to its common terminal, while the first, second, and third selection terminals are all disconnected from their common terminal. The fourth operational amplifier A4 has a non-inverting input terminal, an inverting input terminal, and an output terminal.The non-inverting input of the fourth operational amplifier A4 is grounded. The inverting input of the fourth operational amplifier A4, one end of the sixth resistor R6, one end of the second capacitor C2, one end of the seventh resistor R7, one end of the third capacitor C3, one end of the eighth resistor R8, one end of the fourth capacitor C4, one end of the ninth resistor R9, and one end of the fifth capacitor C5 are connected, and this connection is the input of the programmable gain I / V converter circuit. The other ends of the sixth resistor R6 and the second capacitor C2 are connected to the first selection terminal of the 4-to-1 analog switch S1. The other ends of the seventh resistor R7 and the third capacitor C3 are also connected to the 4-to-1 analog switch S1. The second selection terminal is connected; the other end of the eighth resistor R8 and the other end of the fourth capacitor C4 are connected to the third selection terminal of the four-to-one analog switch S1; the other end of the ninth resistor R9 and the other end of the fifth capacitor C5 are connected to the fourth selection terminal of the four-to-one analog switch S1; the common terminal of the four-to-one analog switch S1 is connected to the output terminal of the fourth operational amplifier A4, and its connection terminal is the output terminal of the programmable gain I / V conversion circuit; the first control terminal of the four-to-one analog switch S1 is the first control terminal of the programmable gain I / V conversion circuit; the second control terminal of the four-to-one analog switch S1 is the second control terminal of the programmable gain I / V conversion circuit.

[0052] In this embodiment of the programmable gain I / V conversion circuit, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 constitute a filter circuit to filter out noise signals in the signal output from the output terminal of the fourth operational amplifier A4. When both the fourth and fifth output terminals of the microcontroller output a low level, the first selection terminal and its common terminal of the four-to-one analog switch S1 are turned on, while the second, third, and fourth selection terminals are turned off from their common terminals. At this time, the amplification factor (i.e., gain) of the programmable gain I / V conversion circuit is determined by the resistance value of the sixth resistor R6. When the fourth output terminal of the microcontroller outputs a low level and the fifth output terminal outputs a high level, the second selection terminal and its common terminal of the four-to-one analog switch S1 are turned on, while the first, third, and fourth selection terminals are turned off from their common terminals. When both the selection terminal and the common terminal are cut off, the amplification factor of the programmable gain I / V converter is determined by the resistance value of the seventh resistor R7. When the fourth output terminal of the microcontroller outputs a high level and the fifth output terminal outputs a low level, the third selection terminal and the common terminal of the four-to-one analog switch S1 are turned on, and the first, second, and fourth selection terminals are cut off from the common terminal. At this time, the amplification factor of the programmable gain I / V converter is determined by the resistance value of the eighth resistor R8. When both the fourth and fifth output terminals of the microcontroller output a high level, the fourth selection terminal and the common terminal of the four-to-one analog switch S1 are turned on, and the first, second, and third selection terminals are cut off from the common terminal. At this time, the amplification factor of the programmable gain I / V converter is determined by the resistance value of the ninth resistor R9.

[0053] Therefore, according to the gain setting instruction, the microcontroller outputs corresponding selection signals at its fourth and fifth output terminals to control the conduction or cutoff between the four selection terminals of the four-to-one analog switch S1 and its common terminal, thereby setting the amplification factor (gain) of the programmable gain I / V conversion circuit and making it output a signal according to the required gain.

[0054] To verify the performance of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention, the host computer sets capacitor charging voltage setting instructions, capacitor discharge polarity setting instructions, and gain setting instructions according to the detection operation requirements of the electrochemical cell. The voltage signal V output from the capacitor discharge signal conditioning circuit is acquired via an oscilloscope under different detection operation conditions. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform diagram is shown. A 10kΩ resistor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of this invention, based on the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction, ensures that when the voltage signal applied to the counter electrode of the electrochemical cell is +1V and the gain is set to 10K according to the gain setting instruction, the voltage signal V output from the capacitor discharge signal conditioning circuit is... o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform is shown in Figure 5(a); a 10kΩ resistor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the voltage signal applied to the counter electrode of the electrochemical cell to +1V and the gain is set to 100K according to the gain setting instruction. The voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V when the voltage signal applied to the counter electrode of the electrochemical cell is +1V and the gain is set to 100K according to the gain setting instruction. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform is shown in Figure 5(b). A 10kΩ resistor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the voltage signal applied to the counter electrode of the electrochemical cell to -1V and the gain is set to 10K according to the gain setting instruction. The voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2The waveform is shown in Figure 5(c). A 10kΩ resistor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the voltage signal applied to the counter electrode of the electrochemical cell to -1V and the gain is set to 100K according to the gain setting instruction. The voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V when the voltage signal applied to the counter electrode of the electrochemical cell is -1V and the gain is set to 100K according to the gain setting instruction. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform is shown in Figure 5(d). A series circuit of 10kΩ resistor and 0.47uF capacitor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the capacitor charging voltage value and the capacitor discharge polarity according to the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction, so that when the voltage signal applied to the counter electrode of the electrochemical cell is +1V and the gain is set to 10K according to the gain setting instruction, the voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform is shown in Figure 6(a). A series circuit of 10kΩ resistor and 0.47uF capacitor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the capacitor charging voltage value and the capacitor discharge polarity according to the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction, so that when the voltage signal applied to the counter electrode of the electrochemical cell is +1V and the gain is set to 100K according to the gain setting instruction, the voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform is shown in Figure 6(b). A series circuit of 10kΩ resistor and 0.47uF capacitor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the capacitor charging voltage value and the capacitor discharge polarity according to the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction, so that when the voltage signal applied to the counter electrode of the electrochemical cell is -1V and the gain is set to 10K according to the gain setting instruction, the voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2The waveform is shown in Figure 6(c). A series circuit of 10kΩ resistor and 0.47uF capacitor is connected between the counter electrode and the working electrode of the electrochemical cell. The microcontroller of the transient potential scanning circuit for photocatalytic reaction detection research of the present invention sets the capacitor charging voltage value and the capacitor discharge polarity according to the capacitor charging voltage value setting instruction and the capacitor discharge polarity setting instruction, so that when the voltage signal applied to the counter electrode of the electrochemical cell is -1V and the gain is set to 100K according to the gain setting instruction, the voltage signal V output by the output terminal of the capacitor discharge signal conditioning circuit is V. o1 The waveform diagram and the voltage signal V output from the output terminal of the programmable gain I / V converter circuit. o2 The waveform is shown in Figure 6(d).

[0055] analyze Figures 5(a) to 5(d) It is known that: with a 10kΩ resistance between the counter electrode and the working electrode of the electrochemical cell, and the simulated electrochemical cell parameters set to a purely resistive load, when the voltage applied to the counter electrode of the electrochemical cell is +1V, the voltage signal V output from the capacitor discharge signal conditioning circuit of the transient potential scanning circuit for photocatalytic reaction detection research of this invention is... o1 The waveform exhibits exponential decay. When the gain changes from 10K to 100K, the voltage signal V output from the programmable gain I / V converter circuit... o2 The waveform amplitude increased significantly, indicating that the programmable gain I / V converter effectively converted the weak current signal into a voltage signal for amplification. The voltage signal applied to the counter electrode of the electrochemical cell changed from +1V to -1V. o1 V o2 A corresponding reversal will also occur, indicating that the capacitor polarity conversion circuit can achieve positive / negative voltage switching.

[0056] analyze Figures 6(a) to 6(d) It can be seen that when a series circuit of a 10kΩ resistor and a 0.47uF capacitor is connected between the counter electrode and the working electrode of the electrochemical cell to simulate the electric double layer effect in actual photocatalytic and electrocatalytic reactions, the voltage signal V output by the programmable gain I / V conversion circuit will be... o1 The decay time is compared to the voltage signal V output from the programmable gain I / V converter circuit when only a 10kΩ resistor is connected between the counter electrode and the working electrode of the electrochemical cell. o1 The decay time is significantly prolonged, which indicates that the transient potential scanning circuit of the present invention, which is designed for the detection of photocatalytic and electrocatalytic reactions, can capture the dynamic response of complex electrochemical interfaces.

[0057] Therefore, it can be seen that the transient potential scanning circuit of the present invention for the detection of photocatalytic and electrocatalytic reactions can accurately capture transient voltage signals under different electrochemical cell parameters (pure resistive, RC series). These experimental results fully support the technological innovations of the transient potential scanning circuit of the present invention for the detection of photocatalytic and electrocatalytic reactions in terms of improving detection accuracy, simplifying operation procedures, and real-time performance.

[0058] In summary, the transient potential scanning circuit of this invention for detecting photocatalytic and electrocatalytic reactions improves the accuracy of capacitor charging voltage settings and reduces the difficulty of detecting weak current signals at the working electrode of the electrochemical cell. The detection process is simple and less prone to errors. By measuring the voltage and current signals of the electrochemical cell during capacitor discharge using the transient potential scanning circuit of this invention for detecting photocatalytic and electrocatalytic reactions, a more accurate, simple, and cost-effective solution is provided for analyzing the in-situ dynamics of charge distribution at different potentials and during photocatalysis.

Claims

1. A transient potential scanning circuit for the detection and research of photocatalytic and electrocatalytic reactions, characterized in that... The system includes a digitally controlled capacitor charging circuit, a capacitor polarity conversion circuit, a capacitor discharge signal conditioning circuit, a programmable gain I / V conversion circuit, and a microcontroller. The capacitor polarity conversion circuit includes a first capacitor. The microcontroller communicates with a host computer via a serial communication protocol, receiving capacitor charging voltage setting instructions, capacitor discharge polarity setting instructions, and gain setting instructions from the host computer based on the detection operation requirements of the electrochemical cell. Upon receiving these instructions, the microcontroller first outputs a corresponding voltage control signal to the digitally controlled capacitor charging circuit, causing the digitally controlled capacitor charging circuit to output a voltage signal equal to the set capacitor charging voltage value. The capacitor polarity conversion circuit described above outputs a polarity control signal according to the capacitor discharge polarity setting command to control the charging and discharge polarity of the first capacitor, so that the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit is equal to the voltage required by the actual experiment; the capacitor discharge signal conditioning circuit is used to follow the voltage applied to the counter electrode of the electrochemical cell by the capacitor polarity conversion circuit and generate a corresponding voltage signal output; when the capacitor polarity conversion circuit applies voltage to the counter electrode of the electrochemical cell, the microcontroller outputs a corresponding gain control signal according to the gain setting command to control the programmable gain I / V conversion circuit to convert the current signal of the working electrode of the electrochemical cell into a voltage signal output according to the set gain.

2. The transient potential scanning circuit for photocatalytic and electrocatalytic reaction detection research according to claim 1, characterized in that... The numerically controlled capacitor charging circuit has an input terminal and an output terminal; the capacitor polarity conversion circuit has an input terminal, an output terminal, and two control terminals, referred to as the first control terminal and the second control terminal, respectively; the capacitor discharge signal conditioning circuit has an input terminal and an output terminal; the programmable gain I / V conversion circuit has an input terminal, an output terminal, and two control terminals, referred to as the first control terminal and the second control terminal, respectively; the microcontroller has an input terminal and five output terminals, referred to as the first output terminal, the second output terminal, the third output terminal, the fourth output terminal, and the fifth output terminal, respectively. The input terminal of the microcontroller is used to connect to the host computer via a serial communication protocol; the first output terminal of the microcontroller is used to output a voltage control signal; the second and third output terminals of the microcontroller are used to output polarity control signals; and the fourth and fifth output terminals of the microcontroller are used to output gain control signals. The input terminal of the electrical circuit is connected to the first output terminal of the microcontroller. The output terminal of the digitally controlled capacitor charging circuit is used to output a voltage signal with a magnitude equal to the set value of the capacitor charging voltage. The output terminal of the digitally controlled capacitor charging circuit is connected to the input terminal of the capacitor polarity conversion circuit. The first control terminal of the capacitor polarity conversion circuit is connected to the second output terminal of the microcontroller. The second control terminal of the capacitor polarity conversion circuit is connected to the third output terminal of the microcontroller. The output terminal of the capacitor polarity conversion circuit is connected to the counter electrode of the electrochemical cell. The input terminal of the capacitor discharge signal conditioning circuit is connected to the counter electrode of the electrochemical cell. The input terminal of the programmable gain I / V conversion circuit is connected to the working electrode of the electrochemical cell. The first control terminal of the programmable gain I / V conversion circuit is connected to the fourth output terminal of the microcontroller. The second control terminal of the programmable gain I / V conversion circuit is connected to the fifth output terminal of the microcontroller.

3. The transient potential scanning circuit for photocatalytic and electrocatalytic reaction detection research according to claim 2, characterized in that... The numerically controlled capacitor charging circuit includes a first resistor, a second resistor, a third resistor, a first operational amplifier, and a second operational amplifier. Both the first and second operational amplifiers have a non-inverting input, an inverting input, and an output. One end of the first resistor is connected to the inverting input of the first operational amplifier, and the non-inverting input of the first operational amplifier is the input of the numerically controlled capacitor charging circuit. The other end of the first resistor, the output of the first operational amplifier, and the non-inverting input of the second operational amplifier are connected. The inverting input of the second operational amplifier, one end of the second resistor, and one end of the third resistor are connected. The other end of the third resistor is grounded. The other end of the second resistor is connected to the output of the second operational amplifier, and this connection point is the output of the numerically controlled capacitor charging circuit.

4. A transient potential scanning circuit for detecting and studying photocatalytic and electrocatalytic reactions according to claim 2, characterized in that... The capacitor polarity conversion circuit further includes a fourth resistor and two relays. Each relay has two normally open terminals, two normally closed terminals, two common terminals, and a control coil terminal. The two normally open terminals are referred to as the first normally open terminal and the second normally open terminal, the two normally closed terminals as the first normally closed terminal and the second normally closed terminal, and the two common terminals as the first common terminal and the second common terminal, respectively. The control coil terminal of the relay is used to receive a control signal. When the control signal received at the control coil terminal of the relay is high, the first normally open terminal is connected to the first common terminal, the second normally open terminal is connected to the second common terminal, the first normally closed terminal is disconnected from the first common terminal, and the second normally closed terminal is connected to the second common terminal. The two relays are referred to as the first relay and the second relay. A relay; one end of the fourth resistor is the input terminal of the capacitor polarity conversion circuit, the other end of the fourth resistor is connected to the first normally closed terminal of the first relay, the second normally closed terminal of the first relay is grounded, one end of the first capacitor is connected to the first common terminal of the first relay, the other end of the first capacitor is connected to the second common terminal of the first relay, the first normally open terminal of the first relay is connected to the first common terminal of the second relay, the second normally open terminal of the first relay is connected to the second common terminal of the second relay, the first normally closed terminal of the second relay is connected to its second normally open terminal, and the connection terminal is the output terminal of the capacitor polarity conversion circuit, both the first normally open terminal and the second normally closed terminal of the second relay are grounded, the control coil terminal of the first relay is the first control terminal of the capacitor polarity conversion circuit, and the control coil terminal of the second relay is the second control terminal of the capacitor polarity conversion circuit.

5. A transient potential scanning circuit for detecting and studying photocatalytic and electrocatalytic reactions according to claim 2, characterized in that... The capacitor discharge signal conditioning circuit includes a fifth resistor and a third operational amplifier. The third operational amplifier has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the third operational amplifier is the input terminal of the capacitor discharge signal conditioning circuit. The inverting input terminal of the third operational amplifier is connected to one end of the fifth resistor, and the output terminal of the third operational amplifier is connected to the other end of the fifth resistor, with the connection terminal serving as the output terminal of the capacitor discharge signal conditioning circuit.

6. A transient potential scanning circuit for detecting and studying photocatalytic and electrocatalytic reactions according to claim 2, characterized in that... The programmable gain I / V conversion circuit includes a fourth operational amplifier, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, and a 4-to-1 analog switch. The 4-to-1 analog switch has four selection terminals, one common terminal, and two control terminals. The two control terminals of the 4-to-1 analog switch are respectively used to receive selection signals. Under the control of the selection signals received by the two control terminals, one of the four selection terminals of the 4-to-1 analog switch is turned on with its common terminal, while the other three are turned off with their common terminal. The four selection terminals of the 4-to-1 analog switch are referred to as its first selection terminal, second selection terminal, third selection terminal, and fourth selection terminal, respectively. The two control terminals of the 4-to-1 analog switch are referred to as its first control terminal and second control terminal, respectively. When the selection signals received by the first control terminal and the second control terminal of the 4-to-1 analog switch are both low, its first selection terminal and its common terminal are turned off. The first selection terminal is connected to the common terminal, while the second, third, and fourth selection terminals are all disconnected from their common terminal. When the selection signal connected to the first control terminal of the four-to-one analog switch is low and the selection signal connected to the second control terminal is high, the second selection terminal is connected to its common terminal, while the first, third, and fourth selection terminals are all disconnected from their common terminal. When the selection signals connected to the first control terminal and the second control terminal of the four-to-one analog switch are both high, the fourth selection terminal is connected to its common terminal, while the first, second, and third selection terminals are all disconnected from their common terminal. The fourth operational amplifier has a non-inverting input terminal, an inverting input terminal, and an output terminal.The non-inverting input terminal of the fourth operational amplifier is grounded. The inverting input terminal of the fourth operational amplifier, one end of the sixth resistor, one end of the second capacitor, one end of the seventh resistor, one end of the third capacitor, one end of the eighth resistor, one end of the fourth capacitor, one end of the ninth resistor, and one end of the fifth capacitor are connected, and this connection is the input terminal of the programmable gain I / V conversion circuit. The other end of the sixth resistor and the other end of the second capacitor are connected to the first selection terminal of the four-to-one analog switch. The other end of the seventh resistor and the other end of the third capacitor are connected to the four-to-one analog switch. The second selection terminal is connected to the fourth capacitor, the other end of the eighth resistor and the other end of the fourth capacitor are connected to the third selection terminal of the four-to-one analog switch, the other end of the ninth resistor and the other end of the fifth capacitor are connected to the fourth selection terminal of the four-to-one analog switch, the common terminal of the four-to-one analog switch is connected to the output terminal of the fourth operational amplifier, and its connection terminal is the output terminal of the programmable gain I / V conversion circuit. The first control terminal of the four-to-one analog switch is the first control terminal of the programmable gain I / V conversion circuit; the second control terminal of the four-to-one analog switch is the second control terminal of the programmable gain I / V conversion circuit.

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