Anatase TiO₂Nanocrystals With Exposed High-energy{001} Facets On Graphene Sheets For Photocatalyst

Owing to extensive practical applications and fundamental importance, controllable synthesis of well-faceted anatase TiO2crystal with high percentage of reactive facets has attracted increasing attention. Theoretical and experimental studies indicate that the {001} facets of anatase TiO2is much more reactive than the thermodynamically more stable{101} facets. Furthermore, many researchers have documented that anatase TiO2with exposed high-energy{001} facets exhibits more valuable potential for various applications (e.g., photocatalyst, Li-ion battery etc.). However, the rapid h＋/e－recombination rate of TiO2(an intrinsic drawback) is not essentially improved. Thus, a favorable conductive substrate to overcome the barrier is urgently demanded. Recently, researchers found that the introduction of carbon materials can enhance the charge separation rate of TiO2-C composites. Graphene, an inexpensive and novel carbon material, was found to serve as a good candidate to composite TiO2to enhance photo induced charge separation of composites because of its excellent electronic property and unique two-dimensional nanostructure. Therefore, it is important to integrate these nano-sized anatase TiO2with exposed{001} facets on the graphene to achieve high efficiency photocatalytic application.Here, nano-sized anatase TiO2sheets mainly dominated by{001} facets had been prepared on graphene sheets by using a facile solvothermal synthetic route. TiO2nanosheets with side lengths of30nm and thickness of7nm could grow on the graphene sheets when the reaction time was set at6h. The percentage of{001} facets in TiO2nanosheets was calculated to be ca.64%. The morphologies, structural properties, growth procedures and photocatalytic activities of the resultant TiO2/graphene nanocomposites were investigated. Importantly, when being used as a photocatalyst under visible light irradiation, it exhibited1.4times and2.8times higher photocatalytic activity toward the degradation of dye than pure TiO2nanosheets exposed78%{001} facets and commercial P25, respectively. Simultaneously, the nanocomposites showed excellent photocatalytic activity after five cycles. The enhancement of photocatalytic activity and stability was attributed to the effective charge anti-recombination of graphene and high catalytic activity of {001} facets.