Nanostructured hybrid heterojunctions have been studied widely for photocatalytic applications due to their superior optical and structural properties. In this work, the impact of angstrom thick atomic layer deposited (ALD) ZnO shell layer on photocatalytic activity (PCA) of hydrothermal grown single crystalline TiO2 nanowires (NWs) is systematically explored. We showed that a single cycle of ALD ZnO layer wrapped around TiO2 NWs, considerably boosts the PCA of the heterostructure. Subsequent cycles, however, gradually hinder the photocatalytic activity (PCA) of the TiO2 NWs. Various structural, optical, and transient characterizations are employed to scrutinize this unprecedented change. We show that a single atomic layer of ZnO shell not only increases light harvesting capability of the heterostructure via extension of the absorption toward visible wavelengths, but also mitigates recombination probability of carriers through reduction of surface defects density and introduction of proper charge separation along the core-shell interface. Furthermore, the ultrathin ZnO shell layer allows a strong contribution of the core (TiO2) valence band holes through tunneling across the ultrathin interface. All mechanisms responsible for this enhanced PCA of heterostructure are elucidated and corresponding models are proposed.

Mineralized biological materials such as shells, skeleton, and teeth experience biomineralization. Biomimetic materials exploit the biomineralization process to form functional organic-inorganic hybrid nanostructures. In this work, we mimicked the biomineralization process by the de novo design of an amyloid-like peptide that self-assembles into nanofibers. Chemically active groups enhancing the affinity for metal ions were used to accumulate silicon and titanium precursors on the organic template. The self-assembly process and template effect were characterized by CD, FT-IR, UV-vis, fluorescence, rheology, TGA, SEM, and TEM. The self-assembled organic nanostructures were exploited as a template to form high-aspect-ratio 1-D silica and titania nanostructures by the addition of appropriate precursors. Herein, a new bottom-up approach was demonstrated to form silica and titania nanostructures that can yield wide opportunities to produce high-aspect-ratio inorganic nanostructures with high surface areas. The materials developed in this work have vast potential in the fields of catalysis and electronic materials.

Induced supramolecular chirality was investigated in the self-assembled peptide amphiphile (PA) nanosystems. Having shown that peptide chirality can be transferred to the covalently-attached achiral pyrene moiety upon PA self-assembly, the chiral information is transferred to molecular pyrene via weak noncovalent interactions. In the first design of a supramolecular chiral system, the chromophore was covalently attached to a peptide sequence (VVAGH) via an e-aminohexanoic acid spacer. Covalent attachment yielded a PA molecule self-assembling into nanofibers. In the second design, the chromophore was encapsulated within the hydrophobic core of self-assembled nanofibers of another PA consisting of the same peptide sequence attached to lauric acid. We observed that supramolecular chirality was induced in the chromophore by PA assembly into chiral nanostructures, whether it was covalently attached, or noncovalently bound. and Stupp 8 groups have shown that a chiral center in an alkyl group of a molecule can affect the overall helicity of a supramolecular polymer. It was also observed that chiral molecules could induce chiral organization of achiral molecules by strong noncovalent interactions, such as electrostatic and coordination interactions; thus representing an interesting tool for control of materials' properties. 9-11Chiral molecules such as peptides are interesting model structures for studying induced chirality. All of the natural amino acids, except glycine, used in mRNA translation are chiral; therefore polypeptides are intrinsically chiral. Molecular chirality of peptides can be used to induce supramolecular chirality upon assembly of individual molecules into one-dimensional nanostructures. 12-14Effective assembly of this type can be achieved when a certain peptide sequence is attached to a hydrophobic fatty acid. Aliphatic peptide amphiphiles (PAs) possess this type of design and exhibit self-assembly properties. Aliphatic PAs comprise an oligopeptide sequence and a covalently attached aliphatic tail, which is typically 12-16 carbon atoms long.15 PAs can self-assemble into various nanostructures such as nanoribbons, nanofibers and micelles 16 depending on their amino acid sequence and aliphatic tail.Here we exploited nanofiber forming PAs, because nanofiber formation leads to helical arrangement of individual PA molecules along the nanofiber axis.17 Helical arrangement stems from the twisted geometry of b-sheets forming the PA nanofibers; nevertheless, helicity is not translated into fiber morphology and lateral stacking of b-sheets interdigitated along hydrophobic tails leads to almost flat nanofibers with helical interior. Nanofibers formed from all-L and all-D peptide isomers are expected to possess leftand right-handed interior, respectively. However, there are some reports on handedness inversion in peptide and protein based nanofibers. 18,19 As shown here, this type of arrangement forces covalently attached or noncovalently encapsulated chromophore molecules to exhibit induced chirality. The lett...