Electrochemical analysis of nanostructured iron oxides using cyclic voltammetry and scanning electrochemical microscopy

摘要

Iron oxides in general and especially hematite, alpha-Fe2O3, have become promising materials for the alkaline water electrolysis and photoelectrochemical water splitting, respectively. In the present study electrocatalytic electrodes with a thin film of alpha-Fe2O3 and with vertically aligned alpha-Fe2O3 nanowires were prepared. Cyclic voltammograms of the alpha-Fe2O3 nanowires revealed differences including a series of three unreported cathodic signals when compared to previously published voltammograms for polycrystalline iron oxides. The generation-collection mode of scanning electrochemical microscopy (SECM) using nanostructured Pt microdisc probes was exploited to detect soluble reaction products formed at the voltammetric peaks of the alpha-Fe2O3 electrode. SECM tip-substrate voltammetry unexpectedly showed that the reduction of Fe-VI to Fe-III on the cathodic sweep is accompanied by significant O-2 evolution. (C) 2016 Elsevier Ltd. All rights reserved.