title: Abnormal Cathodic Photocurrent Generated on an n-Type FeOOH Nanorod-Array Photoelectrode.
abstract: A simple, wet-chemical method for the synthesis of an FeOOH nanorod-array photoelectrode on fluorine-doped tin oxide (FTO) glass is reported. Nanorods of diameter about 35 nm and length about 300 nm have been vertically grown on an FTO substrate. Upon calcination, the FeOOH phase could be easily converted to a hematite structure while maintaining the shape of the nanorod array. An interesting abnormal cathodic photocurrent is generated on the FeOOH nanorod-array photoelectrode under illumination, which is totally different from that obtained on a calcined hematite photoelectrode under the same experimental conditions. The cathodic photocurrent density generated on the FeOOH photoelectrode can also be tuned by applying an electrochemical anodic or cathodic treatment. Detailed analysis has revealed that higher valence state Fe(IV) species in the FeOOH photoelectrode play an important role in sacrificing the photoexcited electrons for generation of the cathodic photocurrent. Comparison between the FeOOH and hematite photoelectrodes allows for a better understanding of the interplay between crystal structure, surface reactions, and photocurrent. The findings on this new abnormal phenomenon could also provide guidance for the design of new types of semiconducting photoelectrochemical devices.
authors.affiliation: Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Chen
authors.affiliation: Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
authors.forename: Miaoqiang
authors.initials: M
authors.lastname: Lyu
authors.affiliation: Shenyang National Lab for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, 110016, Shenyang (P.R. China. gangliu@imr.ac.cn.
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.affiliation: Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia. l.wang@uq.edu.au.
authors.forename: Lianzhou
authors.initials: L
authors.lastname: Wang
keywords: iron oxides; nanorod arrays; nanostructures; photocurrent; water splitting