A tetrathiafulvalene-grafted titanium-oxo-cluster material: self-catalyzed crystal exfoliation and photocurrent response properties

Abstract

Many exfoliation strategies have been developed to prepare 2-D sheet materials from single crystals. However, most of the published research has used micro-scale crystals. The transformation of bulk crystals to micro- or nano-scale structures has rarely been achieved by chemical etching. We report here the preparation of a tetrathiafulvalene (TTF)-grafted titanium-oxo-cluster (TiO–TTF) that can be easily exfoliated at a millimeter scale. This is the first example of a titanium-oxo-cluster successfully combined with a TTF moiety. In an oxygen atmosphere, the red crystal of the TiO–TTF cluster changes to a black ‘crystal’ composed of regularly arranged floorboard-like micro-plates. The exfoliation properties of the material are a result of the easy oxidation of the TTF group and the catalytic properties of the TiO cluster. The TTF moiety in the cluster is not only an oxidation center, but also adds new photoelectroactive properties to the TiO material. An enhanced photocurrent response was observed for the TiO–TTF and TiO–TTF(+) materials.