Project Details
Projekt
High-throughput characterization of multinary transition metal oxide and oxynitride libraries. New materials for solar water splitting with improved properties
Applicants
Professor Dr. Sebastian Fiechter; Professor Dr.-Ing. Alfred Ludwig; Professor Dr. Wolfgang Schuhmann
Subject Area
Physical Chemistry of Solids and Surfaces, Material Characterisation
Analytical Chemistry
Analytical Chemistry
Term
from 2012 to 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 220693802
Using a combinatorial approach discovery and characterization of multinary oxide and oxynitride electrodes for solar water splitting will be accelerated. Fabrication of well-defined thin-film materials libraries will be combined with efficient characterization methods, thus providing quantitative data at high throughput. It is intended to facilitate and speed up the discovery of new efficient materials for solar water splitting. By means of combinatorial reactive sputtering thin-film materials libraries will be deposited in two promising basic systems: Fe-Ti-W-O and Fe-Al-Cr-O. They will be extended by doping (B, N) and substitution (Ta, V, Zr). These libraries will be investigated using high-throughput characterization techniques such as x-ray diffraction, analytical electron microscopy and conductivity measurements. Their photoelectrocatalytic properties will be investigated using an optical scanning droplet cell (OSDC). Potentiodynamic photo- and dark current measurements, photocurrent spectroscopy, determination of the open-circuit potential under illumination and in the dark will be performed. In dependence of the material composition, information about photopotential, bias-potential- and wavelength-dependent photocurrent, type of semiconductor, band gap and its nature, charge recombination, and IPCE values will be obtained. Stable materials with promising photoelectrocatalytic properties and suitable band gap will be synthesized in a focused composition range and investigated using the OSDC for identifying suitable compositions. The libraries will be modified with co-catalysts for oxygen and hydrogen evolution reaction. Especially noble-metal free co-catalysts will be addressed. The co-catalyst material libraries will be investigated using the OSDC in order to in-depth evaluate and optimize the interface between semiconductor and co-catalyst aiming on a substantial decrease of overpotentials. The most promising oxide and oxynitride materials will be prepared using sol-gel deposition and spray pyrolysis as nanostructured and porous layers for investigating the photoelectrochemical properties of the identified compositions by means of a scalable synthesis process. The carrier lifetime of photoexcited electron-hole pairs will be evaluated using sub-ps time-resolved THz photoconductivity and microwave reflectivity. The efficient charge carrier transport will be optimized by nanostructuring of the best identified material systems. In summary, the proposal submitted within SPP 1613 addresses the search of new photoactive and/or photoelectrocatalytically active multinary oxides/oxynitrides as well as composite of these phases characterized by band gaps < 2.3 eV and preferably low overpotentials to obtain an efficient light-induced separation of electron-hole pairs in the process of water splitting.
DFG Programme
Priority Programmes
