title: Photoanodes with Fully Controllable Texture: The Enhanced Water Splitting Efficiency of Thin Hematite Films Exhibiting Solely (110) Crystal Orientation.
abstract: Hematite, α-Fe2O3, is considered as one of the most promising materials for sustainable hydrogen production via photoelectrochemical water splitting with a theoretical solar-to-hydrogen efficiency of 17%. However, the poor electrical conductivity of hematite is a substantial limitation reducing its efficiency in real experimental conditions. Despite of computing models suggesting that the electrical conductivity is extremely anisotropic, revealing up to 4 orders of magnitude higher electron transport with conduction along the (110) hematite crystal plane, synthetic approaches allowing the sole growth in that direction have not been reported yet. Here, we present a strategy for controlling the crystal orientation of very thin hematite films by adjusting energy of ion flux during advanced pulsed reactive magnetron sputtering technique. The texture and effect of the deposition mode on the film properties were monitored by XRD, conversion electron Mössbauer spectroscopy, XPS, SEM, AFM, PEC water splitting, IPCE, transient photocurrent measurements, and Mott-Schottky analysis. The precise control of the synthetic conditions allowed to fabricate hematite photoanodes exhibiting fully textured structures along (110) and (104) crystal planes with huge differences in photocurrents of 0.65 and 0.02 mA cm(-2) (both at 1.55 V versus RHE), respectively. The photocurrent registered for fully textured (110) film is among record values reported for thin planar films. Moreover, the developed fine-tuning of crystal orientation having a huge impact on the photoefficiency would induce further improvement of thin hematite films mainly if cation doping will be combined with the controllable texture.
authors.affiliation: †Regional Centre of Advanced Technologies and Materials, Joint Laboratory of Optics and Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17 listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Stepan
authors.initials: S
authors.lastname: Kment
authors.affiliation: ‡Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.
authors.forename: Patrik
authors.initials: P
authors.lastname: Schmuki
authors.affiliation: §Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 14800 Prague, Czech Republic.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Hubicka
authors.affiliation: †Regional Centre of Advanced Technologies and Materials, Joint Laboratory of Optics and Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17 listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Libor
authors.initials: L
authors.lastname: Machala
authors.affiliation: ‡Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.
authors.forename: Robin
authors.initials: R
authors.lastname: Kirchgeorg
authors.affiliation: ‡Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.affiliation: ‡Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: ‡Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.
authors.forename: Kiyoung
authors.initials: K
authors.lastname: Lee
authors.affiliation: §Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 14800 Prague, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Olejnicek
authors.affiliation: §Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 14800 Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Cada
authors.affiliation: §Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 14800 Prague, Czech Republic.
authors.forename: Ivan
authors.initials: I
authors.lastname: Gregora
authors.affiliation: †Regional Centre of Advanced Technologies and Materials, Joint Laboratory of Optics and Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17 listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Zboril
keywords: Hematite; PEC water splitting; conversion electron Mössbauer spectroscopy; iron oxide; pulsed magnetron sputtering; texture