Combinatorial synthesis and high-throughput characterization of structural and photoelectrochemical properties of...

Porous and photoelectrochemically active Fe-doped WO₃ nanostructures were obtained by a combinatorial dealloying method. Two types of precursor materials libraries, exhibiting dense and nano-columnar morphology were fabricated by using two distinct magnetron sputter deposition geometries. Both libraries were subjected to combinatorial dealloying enabling preparation and screening of a large quantity of compositions having different nanostructures. This approach allows identifying materials with interesting photoelectrochemical characteristics. The dealloying process selectively dissolved Fe from the composition gradient precursor W-Fe materials library, resulting in formation of monoclinic single crystalline nanoblade-like structures over the entire surface. Photoelectrochemical properties of nanostructured Fe:WO₃ films were found to be composition-dependent. The measurement region doped with ∼1.7 at % Fe and a film thickness of ∼ 900-1100 nm displayed highly porous WO₃ nanostructures and exhibited the highest photocurrent density of ∼ 72 μA cm^-2. This enhanced photocurrent density is attributed to the decreased bandgap values, suppressed recombination of electron-hole pairs, improved light absorption as well as efficient charge transport in the highly porous Fe-doped film with single crystalline WO₃ nanoblades.