by Emory S. De Castro
Electrochemistry on gases originated in 1839 with Grove’s “gaseous voltaic battery”. Over 90 years later, Bacon built a demonstration fuel cell consisting of porous nickel electrodes. He is credited with creating a stable three phase reaction zone of electrode, gas, and electrolyte. Today’s fuel cell electrodes are far more sophisticated and lend themselves to other important electrochemical processes.
For example, the electrolytic production of pure hydrogen and oxygen is possible through an SPE® (solid polymer electrolyte) stack where DuPont’s Nafion® cation exchange membrane is the electrolyte. Other processes include gas purification, inorganic salt splitting (caustic from soda ash), or even synthetic applications (electrocatalytic oxidation of ethylene and methane). This review will show how the three-phase region of fuel cells can be exploited to create electrochemical gas sensors.