Studies on dual phase ceria-based composites in electrochemistry

The ceria-based dual-phase composites have been recently developed as functional electrolytes successful for intermediate and low temperature solid oxide fuel cell applications. These composite materials showed many unique advantages over the conventional single-phase electrolytes, such as superionic conduction in two-phase interfaces, dual proton and oxygen ion conduction resulting in extremely high ion conductivity and high current outputs in fuel cell and other applications, e.g. electrolysis. Interfacial superionic conduction is a characteristic for high conducting dual-phase composites. The composite approach can combine or integrate multi-ion functions, typically, dual H⁺ and O^2- conduction together to enhance the material conductivity and device performance. Dual or hybrid H⁺ and O^2-conduction is based on a consideration that both proton (H⁺) and oxygen ion (O^2-) are the fuel cell source ions. Proton conduction is important for LTSOFCs since it can be activated easier than oxygen ions in the low temperature (LT, 300- 600°C) region. The superionic conduction, dual phase proton and oxygen ion transport make significant conduction and electrical contributions for electrochemical devices. This paper makes a review on these recent studies.