TiO₂ Nanocrystals Grown on Graphene as Advanced Photocatalytic Hybrid Materials

A graphene/TiO₂ nanocrystals hybrid has been successfully prepared by directly growing TiO₂ nanocrystals on graphene oxide (GO) sheets. The direct growth of the nanocrystals on GO sheets was achieved by a two-step method, in which TiO₂ 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/H₂O mixed solvent and addition of H₂SO₄ facilitates the selective growth of TiO₂ on GO and suppresses growth of free TiO₂ in solution. The method offers easy access to the GO/TiO₂ nanocrystals hybrid with a uniform coating and strong interactions between TiO₂ and the underlying GO sheets. The strong coupling gives advanced hybrid materials with various applications including photocatalysis. The prepared graphene/TiO₂ nanocrystals hybrid has superior photocatalytic activity to other TiO₂ 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 TiO₂ nanoparticles is essential.