A XAFS Study of the Spontaneous Adsorption of Thiol-Capped Gold Nanoparticles on Carbon

GRUMELLI DORIS; VERICAT CAROLINA; BENITEZ GUILLERMO; VELA MARIA ELENA; GIOVANETTI LISANDRO; RAMALLO LOPEZ, JOSE MARIA; REQUEJO FELIX; SALVAREZZA ROBERTO

Campinas, Brasil

Otro; 18a RAU REUNION ANUAL DE USUARIOS DEL LABORATORIO NACIONAL DE LUZ SINCROTRON; 2008

Laboratorio Nacional de Luz Sincrotron

X-ray absorption fine structure spectroscopy has been used to characterize gold nanoparticle-(AuNP)-modifed carbon surfaces which have been prepared by sim- ple immersion of highly oriented pyrolytic graphite (HOPG) in hexane solutions containing 3 nm diameter thiol-capped nanoparticles. XANES and EXAFS results show that the AuNP adsorb on the HOPG surface free of unbounded thiols, remain- ing unchanged with time. The amount of adsorbed thiol-protected AuNP depends on concentration and time. The reductive desorption of thiols from the AuNP pro- duces an e±cient release of more than 90% of the AuNP from the carbon surface to the aqueous solution. The remaining thiol-free Au nanoparticles do not sinter on the HOPG, forming stable and electrochemically active islands. These results could open interesting possibilities for easy transfer of thiol-capped metallic NP from one environment to another, for controlled release of biomolecules from metallic NP, and for the preparation of catalytic or decontamination systems on large area C surfaces.