The impacts of graphene concentration and thickness on the photocatalytic performance of Bi₁₂TiO₂₀/graphene composite thin films

Bi₁₂TiO₂₀/graphene thin films with different graphene concentration and thickness were deposited through spin coating followed by post annealing. The thin film morphology was determined by SEM images, which showed a granular structure. Both elemental mapping and EDX spectrum confirmed that the Bi₁₂TiO₂₀ and graphene phases were homogenously distributed within the thin film. The crystal structure of Bi₁₂TiO₂₀ was determined by XRD, and the existence of graphene was determined by Raman spectrum. The Rama spectrum also showed that the graphene had similar states in all Bi₁₂TiO₂₀/graphene thin films with different graphene concentration. The photocatalytic testing showed that the mass ratio graphene to Bi₁₂TiO₂₀ at 4% showed the highest photocatalytic performance, and when the thin film was over 100 nm, the thickness did not affect the photocatalytic performance. (paper)