Plasmonic Ag coated BiOBr0.2I0.8 nanosheets grown on graphene with excellent visible-light photocatalytic activity

• Ag coated BiOBr0.2I0.8 nanosheet/graphene sheet-on-sheet composites were synthesized.
• The obtained ternary composites exhibited excellent photocatalytic activity.
• A synergistic effect between the three components of the composites was observed.
• Both the h+ and OH were the active species in the degradation process.

A series of visible light-responsive plasmonic Ag coated BiOBr0.2I0.8 nanosheets are grown on graphene by a combined solvothermal and photodeposition method. The ternary Ag/BiOBr0.2I0.8/graphene nanocomposites exhibit significantly enhanced photocatalytic activity than pristine BiOBr0.2I0.8 and the binary BiOBr0.2I0.8/graphene composite. When the loading amount of Ag is 1.0 wt%, the Ag/BiOBr0.2I0.8/graphene nanocomposite displays the highest photocatalytic activity. The rate constants for the ternary Ag/BiOBr0.2I0.8/graphene composite to degrade rhodamine B (RhB) and methylene blue (MB) are determined to be ∼5.28 and 5.57 times as large as those of pristine BiOBr0.2I0.8, respectively. The high photocatalytic activity is attributed predominantly to the hybridization of the surface plasmonic resonance (SPR) effect of Ag nanoparticles and the specific electronics effect of graphene, thus enhancing the separation of photogenerated charge carriers of BiOBr0.2I0.8. Meanwhile, the excellent adsorption capacity of graphene and the broad absorption in the visible light region also contribute to the enhancement of photocatalytic activity. Both the holes and hydroxyl radicals were the active species in the degradation process.

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