Vacuum-annealing induces sub-surface redox-states in surfactant-structured alpha-Fe2O3 photoanodes prepared by ink-jet printing

Applied Catalysis B-Environmental Volume: 211 Pages: 289-295 Published: 2017

Author(s): Alexander N. Bondarchuk, Laurence M. Peter, Gabriela P. Kissling, Elena Madrid, Josué A. Aguilar-Martínez, Zuhayr Rymansaib, Pejman Iravani, Murilo Gromboni, Lucia H. Mascaro, Aron Walsh, Frank Marken.

Keywords: Hematite films; Photoanode; Water splitting; Oxygen evolution; Solar energy.

Abstract: Transparent nano-structured hematite (a-Fe203) films of approximately 550 nm thickness on tin-doped indium oxide (ITO) have been obtained conveniently by ink-jet printing of a Fe(NO3)(3)/Brij (R) 010 precursor ink and subsequent annealing at 500 C in air. When illuminated with a blue LED (lambda=455 nm, ca. 100 mW cm(-2)), the hematite films exhibited photocurrents of up to 70 mu A cm(-2) at 0.4 V vs. SCE in degrees 0.1 M NaOH electrolyte. Thermal annealing in vacuum at 500 C for 2 h increased photocurrents more than three times to 230 mu Acm(-2) in agreement with previous literature reports for pure hematite materials. These results suggest that a simple ink-jetting process with surfactants is viable. The effects of vacuum annealing on the photoelectrical properties of alpha-Fe2O3 films are discussed in terms of a sub-surface state templating hypothesis based on data gathered from photo-transients, field emission scanning electron microscopy, X-ray photoelectron spectroscopy analysis, X-ray diffraction, photocurrent spectra, and cyclic voltammetry.

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