Interfacial protonic conduction in ceramics

Ceramics displaying protonic conduction have been the subject of intense research due to their potential applications in fuel cells, hydrogen membranes, and water electrolysis equipment. As a result, a number of ceramics presenting high bulk protonic conductivity have been reported; however, overall protonic conductivities in these ceramics are markedly low due to low interfacial conductance. Thus, there has been recent attention to the protonic characteristics in the interface. Interest has greatly increased for nanostructured and heterostructured ceramics using interfacial conductance. Herein, we summarize the interfacial protonic conductivity and the conduction mechanisms reported in ceramics, with a focus on solid oxides.