Au Polyhedron Array with Tunable Crystal Facets by PVP‐Assisted Thermodynamic Control and Its Sharp Shape As Well As High‐Energy Exposed Planes Co‐Boosted SERS Activity

Abstract A route is developed for directly growing 2D Au polyhedron arrays with controllable exposed facets of polyhedron by utilizing the substrate‐supported 2D Au quasi‐spherical nanoparticle arrays as the Au seed arrays, which cannot be realized by traditional lithography. In the reaction system, polyvinyl pyrrolidone (PVP) plays a vital role in guiding the reduced Au atoms and stabilizing the substrate‐supported Au seeds. More importantly, by thermodynamic control, PVP as a capping agent can further direct the formation of {111} facets. The key to guarantee the integrity and periodicity of array is a proper reduction of Au ions and low growth rate of crystal. Benefiting from the higher electric field intensity near the sharp vertexes and edges of Au polyhedra and the exposed {110} facets with high energy, the Au polyhedron array with {110} facets encasing polyhedron exhibits good, stable surface enhanced Raman scattering activity toward 4‐aminothiophenol among the involved arrays. The proposed fabrication approach tremendously enriches the structural diversity of Au nanoarrays on substrates and greatly overcomes the shortcoming of traditional lithography.