Chloride ion refined galvanic replacement: Boosting monodispersity of Au-Ag hollow nanoparticles & their enhanced applications

In this present work, we have redesigned the well-known Turkevich protocol for promoting versatile galvanic replacement, resulting in the synthesis of hollow Au nanostructures by the sacrificial reduction of HAuCl₄ on the as-prepared Ag nanoparticles in the presence of slight excess NaCl in order to dictate their core size to cavity ratio in a highly reproducible manner. The significance of chloride ion interaction in tuning the size/shape control was corroborated with the contrasting effect of other halide ions, namely bromine and iodine. The structure-property functional relationship of these artificial hollow metal nanostructures were not only established using the systematic optical absorption and TEM measurements, but also through enhanced spectroscopy measurements such as SEIRA and SERS, elucidating the dynamic advantage of hollow nanostructures over and above their solid monometallic counterparts. Further, the familiar 4-NA to p-PDA catalytic reduction kinetics demonstrate the unusual zeroth order characteristics in the presence of hollow metal nanostructures, unequivocally distinguishing it from the common first order characteristics associated with the corresponding solid metal nanoparticles, essentially attributed to the morphology tuned accessible higher total surface area, thus exemplifying the aesthetic compliance for future technological applications.