Ferroelectric domain walls provide a fertile environment for novel materials physics. If a polarization discontinuity arises, it can drive a redistribution of electronic carriers and changes in band structure, which often result in emergent 2D conductivity. If such a discontinuity is not tolerated, then its amelioration usually involves the formation of complex topological patterns, such as flux‐closure domains, dipolar vortices, skyrmions, merons, or Hopfions. The degrees of freedom required for the development of such patterns, in which dipolar rotation is a hallmark, are readily found in multiaxial ferroelectrics. In uniaxial ferroelectrics, where only two opposite polar orientations are possible, it has been assumed that discontinuities are unavoidable when antiparallel components of polarization meet. This perception has been borne out by the appearance of charged conducting domain walls in systems such as hexagonal manganites and lithium niobate. Here, experimental and theoretical investigations on lead germanate (Pb5Ge3O11) reveal that polar discontinuities can be obviated at head‐to‐head and tail‐to‐tail domain walls by mutual domain bifurcation along two different axes, creating a characteristic saddle‐point domain wall morphology and associated novel dipolar topology, removing the need for screening charge accumulation and associated conductivity enhancement.
A facile synthetic route is presented that produces a porous Ga‐In bimetallic oxide nanophotocatalyst with atomically thin pore walls. The material has an unprecedented electronic structure arising from its ultrathin walls. The bottom of the conduction band and the top of the valence band of the material are distributed on two opposite surfaces separated with a small electrostatic potential difference. This not only shortens the distance by which the photogenerated charges travel from the sites where they are generated to the sites where they catalyze the reactions, but also facilitates charge separations in the material. The porous structure within the walls results in a large density of exposed surface reactive/catalytic sites. Because of these optimized electronic and surface structures, the material exhibits superior photocatalytic activity toward the hydrogen evolution reaction (HER).more » « less
- NSF-PAR ID:
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie
- Page Range / eLocation ID:
- p. 11614-11618
- Medium: X
- Sponsoring Org:
- National Science Foundation
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