Surfactant-free synthesis of mixed-phase (cubic + hexagonal) gold and gold-graphene core-shell nanowires

We use the following commercially available materials to synthesize all of our samples: multilayer graphene flakes that are on average ~ 8 nm thick and ~ 5 m in lateral size (purchased from Graphene Supermarket, New York) and chloroauric acid (HAuCl4∙xH2O, 99.999% purity, purchased from Sigma-Aldrich, USA). The Au nanowire synthesis process involves hydrothermal reduction of the gold precursor, during which graphene serves not only as the reducing agent but also as the platform for the growth of gold nanowires. First, graphene multilayers (0.5 mg) are dispersed in 10 mL of deionized water in a glass vial. Then 0.5 mL of HAuCl4 (2.85 mM) is added to the vial using a pipette and the suspension is mixed via ultrasonication with a probe sonicator for 30 s to obtain a homogenous solution. The glass vial is capped and heated to 80 oC in the oven and held at the same temperature for up to 16 h for the hydrothermal reduction and the nanowire growth.For specific data, please refer to the file.