Limiting currents in potentiostatic voltammetry without supporting electrolyte

Traditionally, electrochemists study solutions of electroactive salts with excess supporting electrolyte present. The imposition of a large enough pot ential step on a macroelectrode in such a solution results in a limiting cu rrent that obeys Cottrell's equation, declining as t(-1/2). In the present article it is demonstrated that t(-1/2) dependence is preserved even when s upporting electrolyte is absent. The limiting current however is shown to d epart in magnitude from the Cottrellian prediction by a factor (greater or less than unity) that depends on the charge numbers of the salt's ions and that of the electroproduct. (C) 1999 Elsevier Science S.A. All rights reser ved.