Phase transition behaviour and mechanism of 2D TiO2(B) nanosheets through water-mediated removal of surface ligands

Abstract

Phase engineering is a central subject in materials research. The recent research interest in the phase transition behavior of atomically thin 2D materials reveals the important role of their surface chemistry. In this study, we investigated the phase transformation of ultrathin TiO₂(B) nanosheets to anatase under different conditions. We found that the convenient transformation in water under ambient conditions is driven by the hydrolysis of surface 1,2-ethylenedioxy groups and departure of ethylene glycol. A transformation pathway through the formation of protonic titanate is proposed. The ultrathin structure and the metastable nature of the precursor facilitate the phase conversion to anatase. Our finding offers a new insight into the mechanism of TiO₂(B) phase transition from the viewpoint of surface chemistry and may contribute to the potential application of ultrathin TiO₂(B) nanosheets in aqueous environments.