Curcumin-Functionalized Ag/Ag 2 O Nanocomposites: Efficient Visible-Light Z-scheme Photocatalysts.

Curcumin-functionalized Ag/Ag2 O (c-Ag/Ag2 O) nanocomposites with varying proportions of curcumin and Ag/Ag2 O were prepared by a simple one pot green synthesis protocol in aqueous medium. The plasmonic band undergoes slight redshift, broadening and decrease in intensity with increase in the proportion of Ag2 O formed. These composite nanoparticles were found to be efficient visible-light photocatalysts for aerobic oxidation of methyl orange and rhodamine B (RhB). Functionalization by curcumin significantly enhanced the photocatalytic activity with good reusability. The photocatalytic oxidation rate showed super linear increase with light intensity because of localized surface plasmon resonance (LSPR)-induced strong near field. The trapping experiments confirmed that superoxide radicals were the main active species responsible for the degradation reaction. A plasmonic Z-scheme photocatalytic mechanism is proposed to explain the possible charge transfer and separation behavior of electron-hole pairs among Ag, Ag2 O and curcumin under visible-light irradiation.