Shape Transition of TiO₂ Nanocube to Nanospindle Embedded on Reduced Graphene Oxide with Enhanced Photocatalytic Activity

In this study, we report a facile synthetic route for the transition of anatase TiO 2 nanocube to nanospindle with coexposed {001} and {101} facets on a reduced graphene oxide (rGO) platform. Initially, a TiO 2 nanocubes/graphene oxide suspension in an ethanol–water solvent mixture was hydrothermally treated at 180 °C for various reaction durations to perform the in situ growth of TiO 2 and simultaneous reduction of graphene oxide to rGO. All composites resulted in the formation of anatase TiO 2 with a surface heterojunction formed by coexposed {101} and {001} facets embedded on an rGO sheet. Interestingly, it was observed that 4 h of hydrothermal treatment resulted in the formation of a TiO 2 nanospindle with enhanced {001} high energy facet % embedded on an rGO sheet. The photocatalytic performance of the products was evaluated for the photodegradation of malachite green under simulated solar irradiation. All TiO 2 @ rGO composites exerted enhanced activity as compared to the native TiO 2 cube owing to enhanced adsorption and fast electron migration by the rGO platform. Furthermore, the TiO 2 spindle @rGO exhibited the highest photocatalytic activity with a ∼6 fold increase in efficiency over the native TiO 2 cube. This superior performance of the nanospindle was ascribed to the synergistic effect of enhanced {001} facet percentage in the surface heterojunction and close interfacial contact with the rGO platform.