Highly Efficient and Recyclable Nanocomplexed Photocatalysts of AgBr/N-Doped and Amine-Functionalized Reduced Graphene Oxide

Abstract

Although silver bromide has recently drawn considerable attention because of its high photocatalytic activity, it tends to form agglomerated metallic silver under the irradiation of visible light. Therefore, photocatalytic activity decreases with time and cannot be applied for repeated uses. To overcome this limitation, in the present work, we complexed AgBr with nitrogen doped (N-doped) and amine functionalized reduced graphene oxide (GN). N-doped and/or amine functionalized graphene shows intrinsically good catalytic activity. Besides, amine groups can undergo complexation with silver ions to suppress its reduction to metallic Ag. As a result, these complexed catalysts show excellent photocatalytic activity for the degradation of methylene blue (MB) dye under the irradiation of visible light. Photocatalytic degradation of MB shows that the catalytic activity is optimized at a condition of 0.5 wt % GN, under which similar to 99% of MB was degraded only after 50 min of visible light irradiation. Notably, the complexed catalyst is quite stable and retained almost all of its catalytic activity even after greater than 10 repeated cycles. Moreover, the catalyst can also efficiently decompose 2-chlorophenol, a colorless organic contaminant, under visible light exposure. Detailed experimental investigation reveals that hydroxyl (center dot OH) radicals play an important role for dye degradation reactions. A relevant mechanism for dye degradation has also been proposed.