C-oriented and {010} facets exposed BiVO4 nanowall films: Template-free fabrication and their enhanced photoelectrochemical properties

Abstract

Vertically aligned BiVO4 nanowall films on indium tin oxide (ITO) glass have been fabricated through a template-free hydrothermal method for the first time. Based on the structural understanding of both BiVO4 and ITO, the lattice matches ({020}BiVO4 and {040}ITO, {200}BiVO4 and {004}ITO, respectively) and the similarity of metal atomic arrangement parallel to {001} planes turn out to be crucial for the fabrication of the nanowalls. Consequently, the growth of a BiVO4 film begins from heteroepitaxy and undergoes an Ostwald ripening process to form an extended network, resulting in a c-orientation and exposing {010} facets. Through this process, it is much easier to obtain a range of nanowall films with different packing densities, as the surface state of ITO glass is alterable by adjusting the concentration of acid. The films can be directly used as an electrode, which exhibits an excellent response to visible light, especially light with low intensity, allowing for the electrical interconnection, highly active surface, appropriate orientation, and a good contact with the substrate. There are great benefits in improving the technique for detecting the weak light source signals. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.