Application of Coulostatic unarge Injection Techniques to Improve Potentiostat Risetimes

The design of a potentiostat is given which is capable of applying large amounts of peak power (300 watts at 1 μsec) to an electrochemical cell. The design incorporates the use of a coulostatto initially charge the double layer while the potentiostat supplies the relatively small current needed to sustain any electrode processes. For systems with rather high resistances and large capacitances, time improvements of moee than an order of magnitude are indicated with this device. Current-time data are presented on the oxidation of ferrocene-carboxylic acid in acetonitrile which agree with fhe theoretical values to 10 μsec. In addition, internal reflection spectroelectrochemical experiments at optically transparent electrodes follow predicted behavior to less than 4 μsec. This time improvement will greatly extend the use of potentiostatic methods for fast reaction rate studies to highly resistive nonaqueous solvent systems.