Synthesis and characterization of ligand-free Ni nanoclusters

LÓPEZ-QUINTELA, M. ARTURO; RAMALLO-LÓPEZ, JOSÉ M.; MARTÍN MIZRAHI; FELIX G. REQUEJO; DAVID BUCETA; FERNANDO BATTAGLINI; GONZÁLEZ, GRACIELA A.; ANA S. PEINETTI

Campinas

Congreso; 27th Annual Users Meeting; 2017

CNPEM-LNLS

Metal nanoclusters (NC) are a new class of materials which attract a great interest due to their new properties, related with their unique geometric and electronic structures.1, 2 The intrinsic features of these structures do not change monotonically, rather drastically, with the number of atoms, therefore, the control over the synthesis of these assemblies is highly relevant. In this work, the electroreduction of Ni2+ ions inside an ordered mesoporous alumina was studied as function of the current density applied (J). These samples were characterized by AFM, SEM, UV-Vis fluorescence and XAS techniques. Applying a J= 3 mA/cm2 we are able to generate a ligand-free NC of metallic Ni of about 0.7 nm of diameter (see Fig. 1). When the current density is increased, it leads to the generation of nanoparticles (NP) and nanorods (NR). In these cases, we have observed that the metallic state start to disappears to become Ni oxide NP or NR (see Fig. 2). As an example, we use these ligand-free Ni clusters to catalyze the reduction of methylene blue showing an excellent performance.