Enhancement of Photoinduced Visible Light Degradation of Salicylic Acid by Covalently Attached Synthetic Flavins on BiOCl Semiconductor Particle Surfaces

Synthetic derivatives of flavins were covalently attached to the surfaces of BiOCl particles as photosensitizers for facilitating the heterogeneous photocatalytic degradation of organic molecules under visible light. The anchored flavins, tethered through their N3 position, were found to significantly (up to more than 6 times) increase the ability of BiOCl to oxidize salicylic acid upon exposure to visible light. The extent of rate enhancement was found to depend on the type of synthetic flavin, where a compound having a conjugated linker was found to be more active than flavins with nonconjugated linkers. Two competing mechanisms are discussed: One is based on flavin photoexcitation followed by charge transport from the excited flavin to the BiOCl solid support phase. A second (parallel) mechanism hinges on BiOCl photoexcitation instead, followed by charge injection in the opposite direction.