Combinatorial synthesis and high-throughput characterization of structural and photoelectrochemical properties of Fe:WO3 nanostructured libraries

Abstract

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.