A fast ceramic mixed OH^-/H⁺ ionic conductor for low temperature fuel cells.

ABSTRACT: Low temperature ionic conducting materials such as OH^- and H⁺ ionic conductors are important electrolytes for electrochemical devices. Here we show the discovery of mixed OH^-/H⁺ conduction in ceramic materials. SrZr_0.8Y_0.2O_3-δ exhibits a high ionic conductivity of approximately 0.01 S cm^-1 at 90 °C in both water and wet air, which has been demonstrated by direct ammonia fuel cells. Neutron diffraction confirms the presence of OD bonds in the lattice of deuterated SrZr_0.8Y_0.2O_3-δ. The OH^- ionic conduction of CaZr_0.8Y_0.2O_3-δ in water was demonstrated by electrolysis of both H₂¹⁸O and D₂O. The ionic conductivity of CaZr_0.8Y_0.2O_3-δ in 6 M KOH solution is around 0.1 S cm^-1 at 90 °C, 100 times higher than that in pure water, indicating increased OH^- ionic conductivity with a higher concentration of feed OH^- ions. Density functional theory calculations suggest the diffusion of OH^- ions relies on oxygen vacancies and temporarily formed hydrogen bonds. This opens a window to discovering new ceramic ionic conducting materials for near ambient temperature fuel cells, electrolysers and other electrochemical devices.

SUBMITTER: Zou P 

PROVIDER: S-EPMC10827789 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature