1.1 BACKGROUND HISTORY
During the year 1950, metallurgist and physiochemist tried to bring some light into a fascinating electrochemical phenomenon (Bard and Faulkner, 2001) called electrochemistry.
Electrochemist discovered that if an iron electrode is dropped into diluted sulphuric acid (electrolyte), it will instantly start to corrode and if another electrode which will not corrode is inserted into the same electrolyte e.g. Platinum and iron electrode is connected to the negative pole of the current source and the platinum electrode to the positive pole of the current source, the iron dissolves will slow down or even stop depending on the voltage applied. This phenomenon was discovered already in the 17th century by Sir Humphery Davy. When the iron electrode is connected to the positive pole and the voltage increased from very low value to higher ones, the dissolution grows exponentially with increasing voltage. Above a certain current limit depending on the electrode area, the electrolytic composition and temperature, it is found that current suddenly drops to a very low value and the iron electrode stops to dissolve. This phenomenon was detected by Michael Faraday which he called ‘passivity’. Although, this phenomenon has been an object of controversy since then a better understanding of this phenomenon was possible after the invention of the potentiostat.
Although potentiostats are the foundation of modern electrochemical research, they have seen relatively little application in resource poor setting such as undergraduate laboratory courses and the developing world (Aaron et al, 2011). One reason for low penetration of potentiostat is their cost as even the least expensive potentiostat sells for more than a thousand dollars. Inexpensive electrochemical workstations could prove useful in educational laboratories, increasing access to electrochemical based analytical techniques. But with this project work, constructing a potentiostat will not even cost up to a hundred thousand naira as locally sourced material and electronic components available on the shelf will be used.
1.2 AIMS AND OBJECTIVES
This project work is done so as to produce a cheap electrochemical analytical device which can be interfaced with dedicated computer software for real time recording and plotting ofexperimental results.
1.3 SIGNIFICANCE OF THE STUDY
This device is a basic device used in electrochemical research which includes.
1.4 SCOPE OF THE STUDY
The two-electrode potentiostat or bipotentiostat is basically an operational amplifier circuit in conjunction with an electrochemical case which comprises of the electrodes dipped into an electrolyte. It is a device which controls the potential between a pair of electrodes (working electrode and reference electrode) while measuring current flow. It is a control and measuring device.It comprises of an electric circuit which controls the potential across the cell by increasingly sensing changes in the resistance, varying according to the current supplied to the system; a higher resistance will result in a decreased current and vice-versa, in order to keep the voltage constant as described by Ohm’s law.
Most early potentiostats could function independently providing output through a physical data trace. Modern potentiostats are designed to interface with a personal computer and operate through a dedicated software package. This automated software allows rapid shifting between experiments and experimental condition. This computer allows data to be stored and analyzed more effectively rapidly and accurately than historic methods.
The potentiostat to be designed involves electrodes in electrolyte which is activated by the following circuits or sections:
This device is to be interfaced with operating system software on the computer so that results can be easily recorded in real time by measuring, recording and plotting of results into tables and graphs respectively. In this work it will be shown how this device can be designed, constructed and applied in electrochemical research.