Graphene Oxide as a Surfactant and Support for In-Situ Synthesis of Au–Pd Nanoalloys with Improved Visible Light Photocatalytic Activity

Abstract

Traditional ways for the synthesis of bimetallic alloyed nanoparticles involve successive or simultaneous reduction of metallic precursors either in an organic solvent phase or in an aqueous phase. However, these two approaches generally require the use of surfactants or polymers, dendrimers, or ligands as protecting or capping agents in order to achieve stable colloidal bimetallic nanoalloys for potential use, for example, loading them onto supports as heterogeneous catalysts. Here, we report the direct synthesis of stabilizing-molecules-free bimetallic Au–Pd nanoalloys promoted by graphene oxide (GO) in an aqueous phase. Formation of Au–Pd nanoalloys and loading onto the reduced GO (denoted as GR) are accomplished simultaneously. Controlled experiments suggest that GO vividly acts as a unique “solution processable macromolecular surfactant” and 2D “flat-mat” support to promote formation and loading of alloyed Au–Pd bimetallic nanoparticles onto the GR sheet. The as-formed Au–Pd/GR exhibits higher photocatalytic activity than both monometallic Au/GR and Pd/GR, prepared by the same approach toward degradation of dye, Rhodamine B (RhB), which thus demonstrates the promising potential of bimetallic nanoalloys rather than the monometallic one in promoting visible light photocatalysis. It is anticipated that our work could boost further interest for harnessing the versatile soft materials features of GO in solution to synthesize other bimetallic alloy catalysts and exploring their applications in photocatalysis