Ultrafast cyclic voltammetry: performing in the few megavolts per second range without ohmic drop

A new concept of a three-electrode potentiostat involving positive feedback compensation of ohmic drop is used to investigate nanosecond time scales b y allowing the recording of ohmic drop-foe voltammograms at scan rates of a few megavolts per second. This range of scan rates corresponds to the deve lopment of diffusion layers whose widths are only a few nanometers thick. I ndependent tests on dummy cells (Bode plots) demonstrated that the potentio stat behaved excellently in the megavolt per second range. Examination of t he well-established voltammetric reduction of anthracene in highly concentr ated (0.9 M) supporting electrolyte confirmed that this potentiostat allowe d the recording of undistorted ohmic drop-free voltammograms up to 2.25 MV s(-1). (C) 2000 Elsevier Science S.A. All rights reserved.