ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Development of layered WO3/TiO2 nanostructures for photoelectrochemical solar water splitting

Date: 05.11.2013
Time: 10:20 a.m.
Place: Materials Day 2013, Ruhr-Universität Bochum, Bochum, Germany

Chinmay Khare, Ruhr-Universität Bochum, Bochum, Germany
Kirill Sliozberg, Analytische Chemie, Ruhr-Universität Bochum, Bochum, Germany
Robert Meyer, Institut für Werkstoffe, Ruhr-Universität Bochum, Bochum, Germany
Alan Savan, Institut für Werkstoffe, Ruhr-universität Bochum, Bochum, Germany
Wolfgang Schuhmann, Ruhr-Universität Bochum, Bochum, Germany
Alfred Ludwig, Materials Research Department, Ruhr-Universität Bochum, Bochum, Germany

Highly porous layered WO3/TiO2 nanostructures were fabricated by combinatorial magnetron sputtering. By varying sputter pressures diverse WO3 microstructures were obtained by depositing the films in form of wedges. Layers of TiO2 nanocolumns were grown thereon by oblique angle deposition method. This combinatorial fabrication technique enables high-throughput screening of a large quantity of films on the materials libraries with respect to their compositions, thicknesses, microstructures and porosities in order to improve photoelectrochemical (PEC) solar water splitting characteristics. A specially designed scanning droplet cell (SDC) is used to perform the high-throughput PEC characterizations. To assess the PEC characteristics of layered heterostructures, the reference films with individual layers of WO3 and TiO2 were screened. The PEC properties of reference individual layers displayed influence of morphology-based differences. Heterostructures with the layered combination of WO-wedge/TiO2-nanocolumnar exhibited improved PEC properties in comparison to the individual TiO2 and WO3 layers.

The maximum photocurrent density of 0.11 mA/cm2 attained on highly porous combinatorial WO3/TiO2materials libraries is about an order of magnitude higher than that of individual WO3 films and two-fold as that of individual TiO2 layer. The charge separation effect and an efficient charge carrier transfer process enhance the photoconversion efficiency within the WO3/TiO2 heterostructures.

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