Silver-osmium core-shell nanoparticles: Synthesis and heterogeneous persulfate activator

Abstract

A simple route for the synthesis of cetyltrimethylammonium bromide (CTAB) immobilized silver-osmium hydrosols (Ag0–Os0) has been reported by using seedless chemical reduction. The Os0 nanoparticles (blue color hydrosols) were prepared with osmium(III) reduction by sodium borohydride in presence of (CTAB). The surface Plasmon resonance (SPR) peak position of Os0 was observed at 585 nm in an alkaline solution. The Ag0–Os0 exhibits SPR peaks at 409 nm and 445 nm in absence and presence of NaOH. The composition and morphology of Ag0–Os0 were determined with DLS, EDX, FTIR, SEM, TEM, XRD, XPS, and N2-adsorption desorption techniques. XRD shows the presence of CTAB at the surface of Ag0–Os0. Brunauer-Emmett-Teller (BET) surface area, total pore volume, and average pore size calculated for Ag0–Os0 are 66.23 m2/g, 0.34 cc/g, and 8.10 nm, respectively. The pore size results suggest the formation of microporous of Ag0–Os0. The heterogeneous persulfate activation efficiency of Ag0–Os0 was tested in situ chemical oxidation of safranin. The activated system showed a much higher dye oxidation rate compared to either S2O82− or of Ag0–Os0 alone. The activation energy is found to be 59.14 kJ mol−1 for the in-situ degradation of safranin by Ag0–Os0/S2O82− system. The Ag0 enhanced the persulfate activation due to the synergistic effects of Os0. The reaction mechanism of Ag0–Os0 persulfate activation was proposed and discussed.