Electrochemistry of planar solid-state amperometric devices based on Nation((R)) and polybenzimidazole solid polymer electrolytes

The electrochemistry of solid polymer electrolyte-based amperometric device s, fabricated according to a recently introduced planar design concept, was further investigated. The solid protonic conductors used were Nafion (R) - 117 membranes and polybenzimidazole (PBI) films while the working and count er electrodes were Au layers sputtered on the same face of the solid electr olyte and in contact with the gas sample. The test gas was oxygen, and sens ors based on both materials exhibited linear response to oxygen concentrati on changes and response times comparable to those of commercially available sensors. The shape of the oxygen reduction current-potential curves observ ed point to high mass transport rates and the absence of a significant mass transport barrier. A systematic study of the effect of humidity on oxygen reduction and Au surface electrochemistry at the Au/Nafion (R) and Au/PBI i nterface reveals that the fall in the oxygen signal with decreasing humidit y is not merely due to ohmic losses. (C) 2001 Elsevier Science Ltd. All rig hts reserved.