Electrochemical fabrication of decomposable three-dimensional Au nano-coral structure and its surface-enhanced Raman scattering (SERS)

In this work, a reliable surface-enhanced Raman scattering (SERS)-active substrate, three-dimensional gold nano-coral structure (3DGN), was prepared simply by one-step electrodeposition in HAuCl4 and NH4Br solution without the confinement of templates or the guidance of organic surfactants. The final morphology and thickness of 3DGN depend on the concentration of NH4Br and the electrodeposition time. When the concentration of NH4Br was 10.0 mmol/L, as-prepared 3DGN has a uniform structural morphology and exhibits the best SERS activity, spatial uniformity and reproducibility towards rhodamine 6G (R6G). The relative standard deviation (RSD) of the spot-to-spot SERS signals is about 10% according to the intensity of 1506 cm−1 Raman vibration modes of R6G, meeting the requirement of SERS substrate for analytic detection. Additionally, the resulting 3DGN could be decomposed into individual (111)-orientated Au nanocrystals under ultrasonication, providing a facile approach to produce Au nanocrystals.