Poly(ionic liquid)-mediated green synthesis of 3D AuPt flower-like nanoballs with composition-dependent SERS sensitivity and catalytic activity

Bimetallic hierarchical architectures have attracted great research enthusiasm due to the nanounit-constructed self-supporting structures and excellent properties in various applications. Here, a poly(ionic liquid)- modulated method is explored for the synthesis of AuPt flower-like nanoballs (FNBs) from aqueous solution at room temperature. The AuPt FNBs with different Au/Pt ratios possess uniform sizes and shapes (with the diameter of about 440 nm), and are composed of the nanoplates with about 19 nm in the thickness, exhibiting open structures and free-standing features. It is found that the used poly(ionic liquid) of 1-butyl-3-methylimida- zole polystyrene sulfonate ([C4mim]n[PSS]) has a great influence on the growth and assembly of AuPt FNBs. The obtained AuPt FNBs exhibit composition-dependent surface enhanced Raman scattering (SERS) responses and catalytic activity for nitrobenzene hydrogenation. With the increase of Au content, the SERS sensitivity gradually increase and catalytic activity gradually decrease.