The frontispiece image shows SEM images of tube-in-tube (TIT) TiO2 nanostructures with porous walls produced in a single step in HF and DMSO solution. The nanotubes are several micrometers long with an outer diameter of 200 nm. These novel nanostructures show potential for the formation of perpendicularly grown, 1D TiO2 nanotubes with enlarged surface areas due to their porous walls-a clear advantage in photocatalytic and solar energy conversion applications. A study of the mechanism shows that for the formation of the TIT TiO2 nanotubes, the equalfield strength growth and localized dissolution of the formed TiO2 tubular walls dominate the formation of this novel morphology. For more information, please read the Communication “Tube-in-Tube TiO2 Nanotubes with Porous Walls: Fabrication, Formation Mechanism, and Photocatalytic Properties” by X. J. Xu, T. Y. Zhai, D. Golberg, and co-workers, beginning on page on page 444.