Au–Ag bimetallic nanoparticles, binary and ternary mixed micelles as active catalysts for the reduction of [Co(NH3)5Br](NO3)2 by iron(II)

The kinetics of reduction of [Co(NH3)5Br](NO3)2 by Mohrʹs salt has been studied in presence of Au–Ag bimetallic nanoparticle, binary, and ternary mixed micelles. The Au–Ag bimetallic nanoparticles with mole ratio of 0.75:0.25 show higher catalytic activity than that of Au nanoparticles of same particle size. The higher catalytic activity of the bimetallic nanoparticles is mainly for electronic charge transfer from adjacent Ag to Au atoms. The effects of binary mixed micellar environments of anionic with non-ionic surfactants (SDS/TX-100, SDS/Tween 80 and SDS/Brij 35) and ternary (SDS/Tween 20/Brij 35) mixed micellar environment on the electron transfer rate have been determined. These effects are attributed to the effect of the coulombic interactions and compared with that of pure ones. Above the CMC of the mixed micellar systems, the effects are explained quantitatively using a kinetic model.