Enhancing Photoresponse of Nanoparticulate α-Fe2O3 Electrodes by Surface Composition Tuning

Abstract

A facile and general procedure to modify the surface composition of nanostructured α-Fe2O3 electrodes is reported. The method involves uniformly covering nanostructured α-Fe2O3 electrodes with a solution containing metal ions, which form a coating layer of Fe2O3−MxOy solid solutions on α-Fe2O3 nanoparticles upon heating in air. Because of the high surface area and surface reactivity of nanoparticles, a solid-state reaction can be induced at the surface of nanostructured electrodes using a mild heating condition that does not cause an aggregation of nanostructures. Any unreacted residual MxOy oxide layers are removed by dissolution in 1 M NaOH solution where α-Fe2O3 particles and their solid solution coating layers are stable. In this study, Al3+ and Sn4+ ions were incorporated using this method into the surface of a nanoparticulate α-Fe2O3 electrode prepared by electrodeposition. Although scanning electron microscopy and X-ray diffraction studies did not show any detectable morphological or structural cha...