TiO2 nanocrystals grown on graphene as advanced photocatalytic hybrid materials

Abstract

A graphene/TiO 2 nanocrystals hybrid has been successfully prepared by directly growing TiO 2 nanocrystals on graphene oxide (GO) sheets. The direct growth of the nanocrystals on GO sheets was achieved by a two-step method, in which TiO 2 was first coated on GO sheets by hydrolysis and crystallized into anatase nanocrystals by hydrothermal treatment in the second step. Slow hydrolysis induced by the use of EtOH/H 2 O mixed solvent and addition of H 2 SO 4 facilitates the selective growth of TiO 2 on GO and suppresses growth of free TiO 2 in solution. The method offers easy access to the GO/TiO 2 nanocrystals hybrid with a uniform coating and strong interactions between TiO 2 and the underlying GO sheets. The strong coupling gives advanced hybrid materials with various applications including photocatalysis. The prepared graphene/TiO 2 nanocrystals hybrid has superior photocatalytic activity to other TiO 2 materials in the degradation of rhodamine B, showing an impressive three-fold photocatalytic enhancement over P25. It is expected that the hybrid material could also be promising for various other applications including lithium ion batteries, where strong electrical coupling to TiO 2 nanoparticles is essential.