Synthesis and application of high surface area metallic nanostructures

Abstract

The present study involves the synthesis and characterization of hollow Sn, hollow Pb, $Pt/C_{60}$ hybrid and $PtRu/C_{60}$ hybrid nanoparticles. First, Hollow Sn and Pb nanoparticles have been prepared by a rapid injection of an aqueous solution of $SnCl_2$ -poly(vinylpyrrolidone) (PVP, surfactant) and $Pb(OAc)_2 \cdot 3H_2O -PVP$ into an aqueous solution of sodium borohydride (reducing agent) in simple, one-pot reaction at room temperature under an argon atmosphere, respectively. The two hollow nanoparticles have been fully characterized by TEM, HRTEM, SAED, XRD, and EDX analyses. Upon exposure to air, the black Pb hollow nanoparticles are gradually transformed into a mixture of Pb, litharge (tetragonal PbO), massicot (orthorhombic PbO), and $Pb_5O_8$. The order and speed of mixing of the reactants between the metal precursor-PVP and the reductant solutions and stoichiometry of all the reactants are crucial factors for the formation of the two hollow nanocrystals. The Sn and Pb hollow nanoparticles were produced only when 1:(1.5-2) and 1:3 ratios of the Sn and Pb precursors to $NaBH_4$ were employed with a rapid injection, respectively. Second, for the synthesis of Pt nanoparticles with $C_{60}$, $Pt(acac)_2$ (acac = acetylacetonate), $C_{60}$, oleylamine, and oleic acid were mixed with 1,2-hexadecanediol and benzyl ether, followed by heating at 50℃ for 1 h under argon atmosphere. The reaction mixture was slowly heated to reflux temperature for 30 min, and allowed to reflux for additional 30 min. Centrifugation and repeated washing of the precipitates yielded Pt nanoparticles as a black-brown solid. The particles were readily dispersed in various hydrocarbon solvents such as toluene, hexane, and chlorobenzene. The PtRu nanoparticles were synthesized with the same reaction conditions as those of the Pt nanoparticles, except the metal precursors of $Pt(acac)_2$ and $Ru(acac)_3$. The two nanoparticles have been fully characterized by TEM, HRTEM, SAED, XRD, ...