title: Hierarchically structured hematite architectures achieved by growth in a silica hydrogel.
abstract: Biomineralization strategies include the use of hydrogels to direct the formation of composite, single-crystal-like structures with unique structure-property profiles. Application of similar synthetic approaches to transition-metal oxides has the promise to yield low-temperature routes to hierarchically structured crystals that are optimized for a range of applications. Here, growth of hematite (α-Fe2O3) within a silica hydrogel resulted in hierarchical, mosaic crystals preferentially expressing catalytically active {110} facets, which are absent in solution-grown controls. Quantitative structural and compositional analysis reveals architectural changes that begin with the incorporation of silicon into the hematite lattice and propagate through to the nanoscale domain structure and assembly, leading to microscale morphologies that show improved photocatalytic performance. This work demonstrates the potential of applying bioinspired crystallization techniques to design functional oxides with multiscale architectural features.
authors.affiliation: †Department of Materials Science and Engineering, ‡School of Applied and Engineering Physics, and §Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States.
authors.forename: Emily
authors.initials: E
authors.lastname: Asenath-Smith
authors.affiliation: †Department of Materials Science and Engineering, ‡School of Applied and Engineering Physics, and §Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Hovden
authors.affiliation: †Department of Materials Science and Engineering, ‡School of Applied and Engineering Physics, and §Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States.
authors.forename: Lena F
authors.initials: LF
authors.lastname: Kourkoutis
authors.affiliation: †Department of Materials Science and Engineering, ‡School of Applied and Engineering Physics, and §Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States.
authors.forename: Lara A
authors.initials: LA
authors.lastname: Estroff