Scanning electrochemical microscopy. 19. Ion-selective potentiometric microscopy

Potentiometric pH selective tips for scanning electrochemical microscopy (SECM) have been developed and used to image local pH changes in a variety of model chemical systems. Images of pH profiles around a platinum microelectrode during water reduction, a corroding disk of silver iodide in aqueous potassium cyanide, a disk of immobilized urease hydrolyzing urea, and a disk of immobilized yeast cells in glucose solution were obtained. A simple method for fabricating antimony microdisk electrodes suitable for use in SECM is described. The general theory for SECM with potentiometric ion selective tips is also present, assuming that the tip is a purely passive sensor