New phase hollandite-type VOOH quadrangular nanorods: a new smart electrical switch material.

New phase hollandite VOOH with a novel 2 x 2 octahedral molecular sieve has been successfully achieved via an ionic liquid-assisted route. Guided by the theoretical structural analysis, the unique structural characteristics of the infinitely linear V(3+)-V(3+) chains indeed lead to smart electrical switch behaviour as expected, representing the first semiconductor-insulator transition case among the hollandite-type structures.