SU1548742A1 - Device for investigating equilibria and kinetics of electrode reactions by quasiequilibrium thin-layer coulovoltmetric method - Google Patents

Abstract

The invention relates to a device for testing substances by determining their electrochemical parameters and can be used in polarographic instrumentation. The aim of the invention is to improve performance as a result of eliminating additional tuning by measuring the rate constant for a constant response time of a thin-layer cell, increasing informativity by recording the initial current flowing through the cell, and measuring the accuracy of electrochemical parameters by compensating for the solution resistance and leakage currents. A known device containing a potentiostat, an electrochemical thin-cell cell, a current-voltage converter, an integrator, a control system, a step voltage generator, a peak detector, a large-scale amplifier, a comparator, a signal duration meter, a leakage current compensator, and an electrolyte solution compensator are introduced. At the same time, the inputs of the peak detector and the scale amplifier are connected to the output of the current-voltage converter, and their outputs are connected to a comparator that controls the duration meter, the inputs of the leakage current compensator and the resistance of the solution are connected to the current-voltage converter output, and their outputs are connected with the transducer inputs, the voltage forms a positive feedback to compensate for the resistance of the solution, and a negative feedback to compensate for the leakage current. 1 il.

Description

The invention relates to a device for testing substances by determining their electrochemical parameters and can be used in polarographic instrumentation.

The purpose of the invention is to increase productivity as a result of eliminating additional tuning by measuring the rate constant for a constant response time of a thin-layer cell, increasing information content by registering the initial current flowing through the cell and measuring the accuracy of electrochemical parameters by compensating for the solution resistance and leakage currents.

The drawing shows a device for studying the equilibrium and kinetics of electronic reactions.

The device contains a potentiostat 1 thin-layer electrochemical cell 2, a current-voltage converter 3, an integrator 4, a peak detector 5, a large-scale amplifier 6, a comparator 79 meter 8 signal duration, a control system 9, a voltage generator 10, a leakage current compensator 11, a compensator 12 resistance solution.

The first output of the potentiostat 1 is connected to the thin-layer electrochemical cell 2 comparison electrode, its second input is connected to the generator 10S | output with the indicator electrode of cell 2, and the auxiliary electrode of the cell 2 is the first input of the converter 3 and the output of the leakage current compensator 1.

The output of the converter 3 is connected to the inputs of the integrator 4, the compensator 12, the compensator 11, the peak detector 5 and the scale amplifier 6, and the output of the peak detector 5 under is connected to the first input of the compensator 7,. The output of the scale amplifier is connected to the second input of the compensator 7S output connected to the input meters 8 of the duration of the signal, the output of which is connected to the input of the system 9 of the control 9 and the output connected to the generator 10.

The device works as follows.

The working electrode of the thin-layer cell 2 is polarized by the help of potentiostat 1 by the voltage supplied by the generator 10-step voltage. When a voltage step is applied, the current through cell 2 increases sharply and then decreases as equilibrium is established, i n i e i

where I is the current through the cell; 1o-initial current} t - time;

C is the reaction time constant, proportional to the cell thickness and inversely proportional to the reaction rate constant.

The output current-converter voltage-3 signal also changes. Ying

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Tegrator 4 gives a recorded voltage at the output proportional to the amount of electricity passed. The maximum value of the converter 3 current-voltage signal is remembered by the peak detector 5, applied to the recording and to the input of the comparator 7. The other input of the comparator 7 is supplied with the current-voltage converter 3 signal increased several times by the large-scale amplifier 6. .

When the signals at the inputs are equal, the comparator 7 is activated and the duration meter 9 records the response time constant. The duration meter 8 includes a control system 9, which provides a signal for recording information to recording devices, maintains the system at a given voltage until it reaches a given degree of equilibrium, resets integrator 4 and peak detector 5. In addition, before applying the signal to a 10-step generator voltage to start the next voltage step control system 9 connects the leakage current compensator 11 to the input of the current-to-voltage converter 3.

Due to the fact that the output signal of the leakage current compensator 1 is equal to the input one, the output of the current converter converges to zero, compensating for the leakage currents of cell 2. The system 9 starts the integrator 4 into operation with a certain delay, which eliminates the capacitive current at the beginning of the cycle. A portion of the voltage from the output of the converter 3 is supplied with a current-voltage to its non-inverting input through the solution resistance compensator 12. The magnitude of this voltage depends on the resistance of the electrolyte solution in cell 2 and is determined before the experiment. After the supply of the next step, the cycle is completely repeated.

The device works in automatic mode, does not require additional adjustment, has increased information content due to registration of peak current values, increased accuracy due to compensation of cell leakage currents and resistance of electrolyte solution,

The invention should be used in electrochemical instrument making, in laboratories engaged in a comprehensive study of electrochemically active substances.

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Claims (1)

Invention Formula A device for studying the equilibrium and kinetics of electrode reactions by a quasi-equilibrium thin-layer Coulomb-voltometric method, consisting of a potentiostat, a thin-layer electrochemical cell, a current-voltage converter, an integrator, a step voltage generator, a control system that distinguishes -1 with the fact that in order to increase productivity as a result of eliminating additional tuning by measuring the rate constant over the constant response time of a thin layer 2 cell, increasing the information and due to the initial current registration flowing through the cell, and accuracy measuring electrochemical parameters by compensating for the solution resistance and leakage currents, additionally contains a peak detector, a large-scale amplifier, a comparator, a signal duration meter, a leakage current compensator and an electrolyte solution resistance compensator, while the inputs of the peak detector and the large-scale amplifier are connected to the output of the current-to-voltage converter their outputs are connected to a comparator that controls the duration meter, the inputs of the leakage current compensators and the solution resistance oedineny yield transducer current to voltage, and their outputs connected to inputs of the converter current in the voltage resistance of the image to compensate solution positive feedback and to compensate for leakage current - negative. H ten  2 , J one Jk-Ј.