Potentiometric Response Characteristics of Oxide-Coated Gallium Electrodes in Aqueous Solutions

摘要: Abstract This paper reports on the potentiometric response characteristics of gallium electrodes coated with native or anodic oxide layers in aqueous solutions. Solid metallic were prepared by cooling liquid monoliths supported either planar silicon substrates incorporated within glass capillaries. These showed pH responses a slope ca. -38 mV/pH range between 3 and 9. The potentials measured could originate from redox processes involving surface that was formed as result reactions water (and/or OH−), observed using scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDX). Similar measurements examined for capillary-incorporated anodized ice-cooled H2SO4 at 10 V. Although resulting nanoporous oxide-coated did not initially show responses, they exhibited smaller (ca. -30 mV/pH; 3∼9) after solution ≤ 3. observation be explained acid-induced dissolution an oxide-based barrier layer passivated underlying electrode. explanation compatible additional over measurements. Interestingly, contrast to electrodes, Nernstian SO42− ≥ 10−4 M, reflecting presence sulfate doped into during anodization. results provide fundamental knowledge required design miniaturized electroanalytical probes based electrodes.