title: Photoanodes based on TiO2and α-Fe2O3for solar water splitting - superior role of 1D nanoarchitectures and of combined heterostructures.
abstract: Solar driven photoelectrochemical water splitting (PEC-WS) using semiconductor photoelectrodes represents a promising approach for a sustainable and environmentally friendly production of renewable energy vectors and fuel sources, such as dihydrogen (H2). In this context, titanium dioxide (TiO2) and iron oxide (hematite, α-Fe2O3) are among the most investigated candidates as photoanode materials, mainly owing to their resistance to photocorrosion, non-toxicity, natural abundance, and low production cost. Major drawbacks are, however, an inherently low electrical conductivity and a limited hole diffusion length that significantly affect the performance of TiO2and α-Fe2O3in PEC devices. To this regard, one-dimensional (1D) nanostructuring is typically applied as it provides several superior features such as a significant enlargement of the material surface area, extended contact between the semiconductor and the electrolyte and, most remarkably, preferential electrical transport that overall suppress charge carrier recombination and improve TiO2and α-Fe2O3photoelectrocatalytic properties. The present review describes various synthetic methods and modifying concepts of 1D-photoanodes (nanotubes, nanorods, nanofibers, nanowires) based on titania, hematite, and on α-Fe2O3/TiO2heterostructures, for PEC applications. Various routes towards modification and enhancement of PEC activity of 1D photoanodes are discussed including doping, decoration with co-catalysts and heterojunction engineering. Finally, the challenges related to the optimization of charge transfer kinetics in both oxides are highlighted.
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic. stepan.kment@upol.cz schmuki@ww.uni-erlangen.de radek.zboril@upol.cz.
authors.forename: Stepan
authors.initials: S
authors.lastname: Kment
authors.forename: Francesca
authors.initials: F
authors.lastname: Riboni
authors.forename: Sarka
authors.initials: S
authors.lastname: Pausova
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Lingyun
authors.initials: L
authors.lastname: Wang
authors.forename: Hyungkyu
authors.initials: H
authors.lastname: Han
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Hubicka
authors.forename: Josef
authors.initials: J
authors.lastname: Krysa
authors.forename: Patrik
authors.initials: P
authors.lastname: Schmuki
authors.forename: Radek
authors.initials: R
authors.lastname: Zboril