Localized Photoelectrochemistry on a Tungsten Oxide-Iron Oxide Thin Film Material Library
Sprache des Titels:
Englisch
Original Kurzfassung:
ABSTRACT: A WO3?Fe2O3 thin film combinatorial library was fabricated using a vapor phase co-deposition method followed by a combined thermal annealing and oxidation process. The scanning electron microscopy (SEM) analysis of the library microstructure combined with X-ray
diffraction (XRD) investigations suggested that ?-Fe2O3 grains preferentially grow from boundaries of domains, containing finer grains of WO3 and Fe2WO6, forming filiform networks
on the surface. The surface density of the hematite networks depends on the amount of Fe present in the library. Photocurrents measured at different applied biases using Photo Electrochemical
Scanning Droplet Cell Microscopy (PE-SDCM) were analyzed and mapped along the entire compositional spread. A distinctive photocurrent peak was detected at 21.9 atom % Fe, and its
appearance was correlated to the higher amount of hematite present in the library at this specific composition together with a specific WO3 crystallographic orientation ((222) orthorhombic or
(400) monoclinic). This finding is confirmed by qualitative and quantitative XPS surface analysis
at the photocurrent peak position in the material library. Thus the enhancement of the photocurrent cannot be exclusively attributed to certain surface modifications since only hematite
was found on the library surface at the peak composition.
Forschungs-