title: α-Fe2O3/TiO23D hierarchical nanostructures for enhanced photoelectrochemical water splitting.
abstract: We report the fabrication of 3D hierarchical hetero-nanostructures composed of thin α-Fe2O3nanoflakes branched on TiO2nanotubes. The novel α-Fe2O3/TiO2hierarchical nanostructures, synthesized on FTO through a multi-step hydrothermal process, exhibit enhanced performances in photo-electrochemical water splitting and in the photocatalytic degradation of an organic dye, with respect to pure TiO2nanotubes. An enhanced separation of photogenerated charge carriers is here proposed as the main factor for the observed photo-activities: electrons photogenerated in TiO2are efficiently collected at FTO, while holes are transferred to the α-Fe2O3nanobranches that serve as charge mediators to the electrolyte. The morphology of α-Fe2O3that varies from ultrathin nanoflakes to nanorod/nanofiber structures depending on the Fe precursor concentration was shown to have a significant impact on the photo-induced activity of the α-Fe2O3/TiO2composites. In particular, it is shown that for an optimized photo-electrochemical structure, a combination of critical factors should be achieved such as (i) TiO2light absorption and photo-activation vs.α-Fe2O3-induced shadowing effect and (ii) the availability of free TiO2surface vs.α-Fe2O3-coated surface. Finally, theoretical analysis, based on DFT calculations, confirmed the optical properties experimentally determined for the α-Fe2O3/TiO2hierarchical nanostructures. We anticipate that this new multi-step hydrothermal process can be a blueprint for the design and development of other hierarchical heterogeneous metal oxide electrodes suitable for photo-electrochemical applications.
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc, Czech Republic. radek.zboril@upol.cz.
authors.forename: Hyungkyu
authors.initials: H
authors.lastname: Han
authors.forename: Francesca
authors.initials: F
authors.lastname: Riboni
authors.forename: Frantisek
authors.initials: F
authors.lastname: Karlicky
authors.forename: Stepan
authors.initials: S
authors.lastname: Kment
authors.forename: Anandarup
authors.initials: A
authors.lastname: Goswami
authors.forename: Pitchaimuthu
authors.initials: P
authors.lastname: Sudhagar
authors.forename: Jeongeun
authors.initials: J
authors.lastname: Yoo
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Ondrej
authors.initials: O
authors.lastname: Tomanec
authors.forename: Martin
authors.initials: M
authors.lastname: Petr
authors.forename: Ondrej
authors.initials: O
authors.lastname: Haderka
authors.forename: Chiaki
authors.initials: C
authors.lastname: Terashima
authors.forename: Akira
authors.initials: A
authors.lastname: Fujishima
authors.forename: Patrik
authors.initials: P
authors.lastname: Schmuki
authors.forename: Radek
authors.initials: R
authors.lastname: Zboril