(Invited) Recent Progress in Low-Temperature Proton Conducting Ceramics for Hydrogen Isotope Processing

Abstract

Proton conducting ceramics (PCCs) are of considerable interest for use in energy conversion and storage applications, electrochemical sensors, and separation membranes. PCCs that combine performance, efficiency, stability, and the ability to operate at low temperatures are particularly attractive for these applications. This presentation summarizes the progress made towards developing low temperature proton conducting ceramics (LT-PCCs), which are defined as operating in the temperature range of 25-400°C. The structure of these ceramic materials, the characteristics of proton conducting mechanisms, and the potential applications for LT-PCCs will be summarized with particular emphasis paid to interfacial protonic conduction. Three temperature zones are defined in the LT-PCC operating regime based on the predominant proton transfer mechanism occurring in each zone. The variation of material properties such crystal structure, conductivity, microstructure, fabrication methods required to achieve the requisite grain size distribution, along with typical strategies pursued to enhance the proton conduction are addressed. Finally, a perspective regarding applications of these materials to low temperature (LT) solid oxide fuel cells, hydrogen separation membranes and emerging areas in the nuclear industry including off gas capture and isotopic separations are presented. Figure 1