We present a transparent and flexible optoelectronic material composed of vertically aligned ZnO NWs grown on reduced graphene/PDMS substrates. Large-area reduced graphene films were prepared on PDMS substrates by chemical exfoliation from natural graphite via oxidative aqueous dispersion and subsequent thermal reduction. ZnO NWs were hydrothermally grown on the reduced graphene film substrate and maintained their structural uniformity even in highly deformed states. The electrical contact between semiconducting ZnO NWs and the metallic graphene film was straightforwardly measured by electric force microscopy (EFM). It shows a typical metal-semiconductor ohmic contact without a contact barrier. Owing to the mechanical flexibility, transparency, and low contact barrier, the ZnO NWs/graphene hybrids show excellent field emission properties. Low turn-on field values of 2.0 V mm À1 , 2.4 V mm À1 , and 2.8 V mm À1 were measured for convex, flat, and concave deformations, respectively. Such variation of field emission properties were attributed to the modification of ZnO NWs emitter density upon mechanical deformation.

We report an efficient and environmentally benign biomimetic mineralization of TiO(2) at the graphitic carbon surface, which successfully created an ideal TiO(2)/carbon hybrid structure without any harsh surface treatment or interfacial adhesive layer. The N-doped sites at carbon nanotubes (CNTs) successfully nucleated the high-yield biomimetic deposition of a uniformly thick TiO(2) nanoshell in neutral pH aqueous media at ambient pressure and temperature and generated N-doped CNT (NCNT)/TiO(2) core/shell nanowires. Unlike previously known organic biomineralization templates, such as proteins or peptides, the electroconductive and high-temperature-stable NCNT backbone enabled high-temperature thermal treatment and corresponding crystal structure transformation of TiO(2) nanoshells into the anatase or rutile phase for optimized material properties. The direct contact of the NCNT surface and TiO(2) nanoshell without any adhesive interlayer introduced a new carbon energy level in the TiO(2) band gap and thereby effectively lowered the band gap energy. Consequently, the created core/shell nanowires showed a greatly enhanced visible light photocatalysis. Other interesting synergistic properties such as stimuli-responsive wettabilites were also demonstrated.

We report on the synthesis of one-dimensional (1D) Li 4 Ti 5 O 12 nanofibers through electrospinning and their outstanding electrochemical performances. Li 4 Ti 5 O 12 with a spinel structure is a promising candidate anode material for lithium rechargeable batteries due to its well-known zerostrain merits. In order to improve the electronic properties of spinel Li 4 Ti 5 O 12 , which are intrinsically poor, we processed the material into a nanofiber type of architecture to shorten the Li + and electron transport distance using a versatile electrospinning approach. The electrospun Li 4 Ti 5 O 12 nanofiber showed significantly enhanced discharging/charging properties, even at high rates that exceeded 10 C, demonstrating that the nanofiber offers an attractive architecture for enhanced kinetics.

Here we introduce angle-resolved piezoresponse force microscopy ͑AR-PFM͒, whereby the sample is rotated by 30°increments around the surface normal vector and the in-plane PFM phase signals are collected at each angle. We obtained the AR-PFM images of BaTiO 3 single crystal and cube-on-cube epitaxial ͑001͒ BiFeO 3 ͑BFO͒ thin film on SrRuO 3 / SrTiO 3 substrate, and confirmed that the AR-PFM provides more unambiguous information on the in-plane polarization directions than the conventional PFM method. Moreover, we found eight additional in-plane polarization variants in epitaxial BFO thin films, which are formed to mitigate highly unstable charged domain boundaries.