Highly efficient silver-assisted reduction of graphene oxide dispersions at room temperature: mechanism, and catalytic and electrochemical performance of the resulting hybrids

Metal-assisted reduction of graphene oxide (GO) has recently emerged as a fast, efficient and room-temperature method towards the preparation of chemically derived graphene, but according to the mechanisms of reduction that have been proposed, not all relevant metals ( e.g. , Ag) should be a priori effective for this purpose. Here, we show that aqueous GO dispersions can be very efficiently reduced at room temperature with NaBH 4 using Ag nanoparticles (Ag NPs) as catalysts, either generated in situ from appropriate precursors (AgNO 3 ) or added to the dispersions as pre-formed objects. We propose and investigate a reduction mechanism that involves the charging of the Ag NPs with excess electrons obtained from the oxidation of a product of the spontaneous hydrolysis of NaBH 4 in the aqueous medium. These excess electrons are then transferred to the GO sheets, triggering their reduction. The catalytic and electrochemical performance of the reduced GO–Ag NP hybrids that result from this process has also been examined. In particular, the hybrids are seen to exhibit very high catalytic activity in the reduction of 4-nitrophenol to 4-aminophenol as a model reaction, and are also effective towards the electrochemical reduction of H 2 O 2 .