In situ ionic-liquid-assisted synthesis of plasmonic photocatalyst Ag/AgBr/g-C3N4 with enhanced visible-light photocatalytic activity

A series of visible-light-induced Ag/AgBr/g-C3N4 nanocomposites were fabricated vis a one-pot and simple approach. The ionic liquid 1-octyl-3-methylimidazolium bromide ([Omim]Br) was introduced into the synthesis system, and served not only as the Br source but also as a dispersant. The Ag/AgBr nanoparticles were found to be highly dispersed on the sheets of g-C3N4. The Ag/AgBr/g-C3N4 nanocomposites showed much higher visible-light-driven photocatalytic activity than individual g-C3N4 and Ag/AgBr for organic compound degradation. The optimal Ag/AgBr content with the highest photocatalytic activity is determined to be 40%, which is almost 2.4 and 1.9 times higher than that those of individual g-C3N4 and Ag/AgBr for the degradation of methylene blue (MB), and 18.8 and 1.6 folds for the degradation of phenol. The enhancement in photocatalytic activity should be assigned to the extended light-absorption range and efficient charge separation as a result of the surface plasmon resonance effect of Ag-0 and the well-matched overlapping band-structure between Ag/AgBr and g-C3N4. Finally, the possible mechanism for the charge separation and transformation among Ag, AgBr and g-C3N4 ternary system under the visible light is proposed. (C) 2015 Elsevier B.V. All rights reserved.