Synthesis of composition and size controlled AuAg alloy nanocrystals via Fe2+-assisted citrate reduction

We report one new method for direct synthesis of monodisperse, quasi-spherical AuAg alloyed nanocrystals (ANCs) with sizes of 11 to 25 nm and core–shell (CS) AuAg@AuAg NCs (CS AuAg ANCs) with sizes of 30 to 80 nm via the Fe2+-assisted citrate coreduction of auric ions and silver ions in a one-pot reaction. It is found that at fixed concentration of auric ions, the concentrations of ferrous ions and silver ions play key roles in tuning the size and the types of NCs (AuAg ANCs and CS AuAg ANCs), respectively. Moreover, AuAg ANCs and CS AuAg ANCs exhibit excellent and poor chemical stability in nonideal chemical environments, respectively. The potential application of these AuAg ANCs for SERS detection of industrial pollutants (such as benzidine and p-cresol) in artificial industrial wastewater has been successfully demonstrated.