Size Dependent Cation Channel in Nanoporous Prussian Blue Lattice

Cation and/or molecule transfer within nanoporous materials can be utilized in, for example, electrochromic devices, hydrogen storage, molecular sensors, and molecular filters. Here, we investigated the mobilities of cations, Na(+), K(+), and Rb(+), in vacancy-controlled Prussian blue film, Na(x)Co[Fe(CN)(6)](1-v)zH(2)O (v is vacancy concentration) with a jungle gym structure. We found that only the smallest Na(+) ions pass through the cubic planes of the lattice, while the larger cations, i.e., K(+) and Rb(+), take a detour channel along the [Fe(CN)(6)] vacancy. The size-dependent cation channel is well understood in terms of the potential curve derived by an ab initio total energy calculation. (C) 2009 The Japan Society of Applied Physics