Discovery of high conductivity in nanosheets

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Layered double hydroxide (LDH) nanosheets have exceptionally high hydroxyl ion (OH-) conductivity, say a NIMS research group.

According to the researchers, the OH- conductivity is 10 to 100 times higher than that of conventional OH- conductors, and is the highest even among inorganic anion conductors.

LDH nanosheets may be applicable as solid electrolytes for alkaline fuel cells and water electrolysers, among other devices.

In fuel cells, hydrogen ion (H+) conductors are usually used as electrolytes. However, the use of H+ conductors requires the use of platinum-based catalysts.

It is said to be feasible to employ OH- in place of H+ as the conducting ion. When OH- is used, the operating environment is alkaline, allowing the use of iron, cobalt and nickel as catalysts, which the team claims reduces production costs.

The major issue with this approach, however, is that the conductivity of OH- in existing OH- conductors is low (10-3 to 10-2S/cm).

In this study, the research group exfoliated LDHs into single layers in chemical reactions, and measured the ionic conductivity of the resulting single-layer nanosheets. The nanosheets demonstrated high conductivities of up to 10-1S/cm at room temperature.

According to the team, the conductivity attained in this study is higher than that of any other OH- conductor reported previously.

The researchers believe the study’s findings may serve as a major step toward the realisation of solid fuel cells.