MICROELECTRODE ENSEMBLES BASED ON OVERLAYING ULTRATHIN POROUS POLYACRYLONITRILE ON DENSE CARBON-FILMS

A new procedure for preparing microelectrode ensembles, based on casti ng an ultrathin microcellular polyacrylonitrile (PAN) insulating foam onto a dense carbonized PAN film, is described. The resulting partiall y blocked surfaces display the behavioral characteristics of ensembles of recessed microelectrodes (of small depth), with steady-state curre nts at moderate and long timescales. Cyclic voltammetry and chronoampe rometry were used to elucidate the electrochemical behavior, while sca nning electron microscopy sheds useful light on the surface microstruc ture. Square-wave stripping voltammetry is demonstrated for the quanti fication of nanomolar concentrations of lead using short deposition pe riods and unstirred solutions. These and other PAN-derived composite e lectrodes present new opportunities for various electrochemical and an alytical applications.