Hydrothermal synthesis of gold nanoplates and their structure-dependent LSPR properties

We developed a facile hydrothermal method to synthesize gold nanoplates with the assistance of surfactant cetyltrimethylammonium chloride (CTAC). Gold nanostructure shapes from triangular, truncated triangular to hexagonal morphology with different sizes can be obtained by accommodating the molar ratios of the surfactant to the gold precursor ([CTAC]/[HAuCl₄]). The edge width of gold nanoplates could also be adjusted from tens to hundreds of nanometers, and even several microns. The growth mechanism analysis reveals that the surfactant CTAC directs and promotes the growth of the tabular {111} facets to form nanoplate structures with the size and shape variations. The structure-dependent localized surface plasmon resonance of different gold nanoplates was theoretically and experimentally explained by finite element method simulation and surface-enhanced Raman scattering (SERS) enhancement, respectively. Based on the Raman spectrum analysis of the marker molecule 4-mercaptobenzoic acid (4-MBA) labeled with different gold nanoplates, it demonstrates that the enhanced SERS performance relies on the different plasmonic properties of the gold nanoplates. Therefore, the gold nanoplates may have potential applications in SERS-based sensing and imaging field.