Ti-modified imogolite nanotubes: highly photoactive nanoreactors for H2 production

Imogolite nanotubes present a unique spatial separation of conduction and valence bands but the large bandgap inhibits potential application as a photocatalyst. The first step toward using these well-defined nanotubes in photocatalysis and exploiting their natural polarization-promoting charge separation across the nanotubes wall, is to tune their bandgap energy. Here, titanium modified double walled aluminogermanate imogolite nanotubes are prepared to overcome this limitation. Structural and optical properties are determined at different scales and the photocatalytic performance is evaluated for H2 production under UV-visible light irradiation. Although the incorporation of Ti atoms into the structure remains limited, the resulting nanotubes reveal a remarkable hydrogen evolution rate of ~1500 µmol g-1 h-1, corresponding to a 65-fold increase relative to a reference TiO2P25 photocatalyst. These results confirm the theoretical predictions regarding the untapped potential of modified imogolite nanotubes as promising 1D photoactive polarized nanoreactors.