Ag⁺-assisted heterogeneous growth of concave Pd@Au nanocubes for surface enhanced Raman scattering (SERS)

AgNO₃ is often used in the preparation of Au nanostructures since Ag-based substances (AgBS) can selectively be adsorbed on Au(100) and significantly modulate the growth of Au nanocrystals. High-index-faceted Au nanostructures have demonstrated excellent performance in catalysis and surface enhanced Raman scattering (SERS), thus attracting the interest of many researchers in the past several decades. Herein, high-index-faceted Pd@Au concave nanocubes (CNCs) were prepared using AgBS as growth-directing agents in the heterogeneous growth of Au on Pd nanocubes (NCs). During the growth of Pd@Au CNCs, Au atoms are initially deposited on the Pd{100} facets leading to the formation of thin Au shells, and then AgBS are quickly adsorbed on the formed Au(100), favoring the growth along <111> and the formation of Pd@Au CNCs. Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), high angle annular dark field (HAADF), and scanning transmission electron microscopy EDS (STEM- EDS) were used to systematically investigate the growth of Pd@Au CNCs. We also demonstrated that the high-index-faceted Pd@Au CNCs exhibited excellent SERS performances.