Size Controlled Synthesis of Tellurium Nanorices by Galvanic Displacement Reaction of Aluminum

Abstract

Tellurium nanostructures were synthesized by galvanic displacement reaction (GDR) of aluminum in an alkaline solution containing TeO32- ions. Due to negative redox potential of Al/AlO2- (i.e., -2.50 V vs. sat. Ag/AgCl), TeO32- (+IV) can be reduced to Te-2(2-) (-I) and Te-2(-) (-II), which resulted in the deposition of Te (0) nanostructures in the solution via chemical reaction between Te-2(2-) or Te-2(-) and TeO32-. The deposition mechanism led to the formation of unique "rice-like" nanostructures in the solution instead of branched structures on the substrate. The sharp tips of the "rice-like" nanostructures may be attributed to the high density of surface charges at the tips. The morphology, diameter and aspect ratio of Te "rice-like" nanostructures were altered by the TeO32- concentration, solution pH, reaction time and the reaction temperature. Electrochemical analytical methods, including open circuit potential (OCP) and linear polarizations (LPs), were used to investigate the reaction mechanisms. The enhancement of piezoelectric constant (d(11)) of nanorices at small diameter was probably due to a flexoelectric effect. (C) 2015 Elsevier Ltd. All rights reserved.