Electrocatalysis Involving High Temperature Proton-Conducting Oxides: Intriguing Experimental Observations & Theoretical Implications

Abstract

High temperature proton conducting oxides were discovered in the 1980s, and they exhibit, depending on temperature and atmosphere, conduction of proton as well as oxygen vacancy and electron hole at temperatures of ~400-900 oC. From electrocatalysis point of view, the conduction of proton together with oxygen vacancy and hole present new opportunity to tailor the electrode reaction process for high temperature electrochemical reactions, which could provide, sometimes surprisingly, new features that may benefit efficient energy conversion and chemical production. Using the electrochemical system of solid oxide fuel cells (SOFC) as an example, this presentation will show incorporating proton conducting oxides as electrolyte and/or (part of) the electrodes in SOFC leads to interesting experimental observations such as improved resistance to poisoning by hydrogen sulfide (H2S), better resistance to deactivation by deposition of carbon, and higher open circuit voltage. The theoretical implications of these intriguing observations will be discussed in terms of the possible changes in the underlying electrochemical reaction mechanisms, and the directions for future research will be pointed out.