A new route to grow oxide nanostructures based on metal displacement deposition. Lanthanides oxy/hydroxides growth

A metal displacement reaction has been used in order to cause precipitation of oxide nanostructures within pores of anodic alumina membrane (AAM) templates. Here, we focus on the displacement deposition of LnO/OH (Ln = La, Ce, Sm, Er) nanostructures using Zn as sacrificial anode, employing a specific cell arrangement where a galvanic couple was formed between zinc anode and the Au thin layer covering template pore bottom. Progress of displacement deposition reaction into template channels was monitored measuring the open circuit potential as well as pH changes of the electrolyte. A progressive de-activation of the anode surface was observed for long deposition times, caused by deposition of passivating oxides on the anodic area. Deposited LnO/OH oxides were investigated by energy dispersion spectroscopy. X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Morphological characterisation revealed that at room temperature a mixed wire/tubular structure was obtained in the case of La and Sm, whilst only tubular structure was observed for Ce and Er. (C) 2012 Elsevier Ltd. All rights reserved.