Sorption of hydrogen onto titanate nanotubes decorated with a nanostructured Cd3[Fe(CN)6]2 Prussian Blue analogue

Nanostructured films of cadmium hexacyanoferrate (III), Cd3[Fe(CN)6]2 have been deposited on the surface of titanate nanotubes (TiNT) by ion exchange with CdSO4, followed by reaction with K3[Fe(CN)6] in an aqueous suspension. The composite demonstrates a significantly higher hydrogen storage uptake than pure Cd3[Fe(CN)6]2 and TiNT. At a temperature of 77 K and a pressure 100 bar, the hydrogen uptake for the composite is approximately 12.5 wt %, whereas only 4.5 wt % and 4 wt % are achieved for the TiNT and Cd3[Fe(CN)6]2 respectively. Electron microscopy and infrared spectroscopy show that Cd3[Fe(CN)6]2 is uniformly distributed on the surface of the nanotubes forming a discontinuous nanostructured film with a well developed interface, which allows efficient interaction with the support. The possible reasons for the high uptake of hydrogen in the composite are discussed.

► Cd3[Fe(CN)6]2/titanate-nanotube composite is formed by ion-exchange, precipitation.
► The composite exhibits a 12.5 wt % of H2 uptake at 77 K and 100 bars.
► The hydrogen uptake is fully reversible.
► H2 uptake in composite is three-fold higher than in the pure components.
► There is a strong interaction between the Cd3[Fe(CN)6]2 and nanotubes.