Assessment of Layered Oxides (H2Ti3O7) as Viable Alternative to Perovskite (BaZr1-xYxO3-y) for Protonic Ceramic Fuel Cells: Insights from Atomic-Scale Simulations

Owing to its intermediate operation temperature (500–800°C), protonic ceramic fuel cells (PCFCs) suffer from poor proton migration kinetics that greatly hampers the hydrogen conversion efficiency. To overcome such drawbacks, BaZr₁₋ₓYₓO₃₋ᵧ (BZYO) with a perovskite structure has been widely employed as a representative proton-conducting electrolyte for PCFCs. Its high proton conductivity originates from the presence of abundant oxygen vacancies, favorable hydration reactions, and a large lattice free volume that facilitates proton migration. Such characteristics, interestingly, are also reported in layered oxides. H₂Ti₃O₇, for instance, possesses a large lattice free volume and readily forms oxygen vacancies as intrinsic defects, implying its capability to achieve high proton conductivity. In this study, we investigate and compare the proton conduction mechanisms of H₂Ti₃O₇ and BZYO using density functional theory and molecular dynamics simulations, with the aim of assessing the feasibility of layered H₂Ti₃O₇ as a proton-conducting electrolyte for PCFC applications.