Time-dependent water uptake in a polymer model coating visualized by FTIR microscopy using a focal plane array detector

Progress of the delamination front during cathodic delamination was imaged by FTIR microscopy. Delamination experiments were carried out using H2O and D2O-based electrolytes. Inhomogeneous propagation of the delamination front was observed

The role of vacancy condensation for the formation of voids in rutile TiO2 nanowires

Titanium dioxide nanowire (NW) arrays are incorporated in many devices for energy conversion, energy storage, and catalysis. A common approach to fabricate these NWs is based on hydrothermal synthesis strategies. A drawback of this low-temperature method is that the NWs have a high density of defects, such as stacking faults, dislocations, and oxygen vacancies. These defects compromise the performance of devices. Here, we report a postgrowth thermal annealing procedure to remove these lattice defects and propose a mechanism to explain the underlying changes in the structure of the NWs. A detailed transmission electron microscopy study including in situ observation at elevated temperatures reveals a two-stage process. Additional spectroscopic analyses and X-ray diffraction experiments clarify the underlying mechanisms. In an early, low-temperature stage, the as-grown mesocrystalline NW converts to a single crystal by the dehydration of surface-bound OH groups. At temperatures above 500 °C, condensation of oxygen vacancies takes place, which leads to the fabrication of NWs with internal voids. These voids are faceted and covered with Ti3+-rich amorphous TiOx

Role of Vacancy Condensation in the Formation of Voids in Rutile TiO₂ Nanowires

Titanium dioxide nanowire (NW) arrays are incorporated in many devices for energy conversion, energy storage, and catalysis. A common approach to fabricate these NWs is based on hydrothermal synthesis strategies. A drawback of this low-temperature method is that the NWs have a high density of defects, such as stacking faults, dislocations, and oxygen vacancies. These defects compromise the performance of devices. Here, we report a postgrowth thermal annealing procedure to remove these lattice defects and propose a mechanism to explain the underlying changes in the structure of the NWs. A detailed transmission electron microscopy study including in situ observation at elevated temperatures reveals a two-stage process. Additional spectroscopic analyses and X-ray diffraction experiments clarify the underlying mechanisms. In an early, low-temperature stage, the as-grown mesocrystalline NW converts to a single crystal by the dehydration of surface-bound OH groups. At temperatures above 500 °C, condensation of oxygen vacancies takes place, which leads to the fabrication of NWs with internal voids. These voids are faceted and covered with Ti³⁺-rich amorphous TiO_<i>x</i>

Low-Copy Number Protein Detection by Electrode Nanogap-Enabled Dielectrophoretic Trapping for Surface-Enhanced Raman Spectroscopy and Electronic Measurements

We report a versatile analysis platform, based on a set of nanogap electrodes, for the manipulation and sensing of biomolecules, as demonstrated here for low-copy number protein detection. An array of Ti nanogap electrode with sub-10 nm gap size function as templates for alternating current dielectrophoresis-based molecular trapping, hot spots for surface-enhanced Raman spectroscopy as well as electronic measurements, and fluorescence imaging. During molecular trapping, recorded Raman spectra, conductance measurements across the nanogaps, and fluorescence imaging show unambiguously the presence and characteristics of the trapped proteins. Our platform opens up a simple way for multifunctional low-concentration heterogeneous sample analysis without the need for target preconcentration

Nanostructured Few-Layer Graphene with Superior Optical Limiting Properties Fabricated by a Catalytic Steam Etching Process

Tailoring the morphology and structure of graphene can result in novel properties for advanced applications. Here, we demonstrate the fabrication of nanostructured few-layer graphene through a mild etching process via catalytic steam gasification of carbon by Fe nanoparticles (NPs). Controlling the reaction temperature, steam concentration, and the loading density of the NPs enables the finetuning of the etching level of graphene. Well-defined nanotrenches with a width of less than 25 nm were formed by channeling of the catalytic NPs. Etching caves and  quasisemicircular etched edges were observed as well. The nonlinear optical properties of the resulting nanostructured graphene were studied under a 532 nm nanosecond pulse laser through an open-aperture apparatus. At the same level of the linear extinction coefficient, it exhibits superior optical limiting performance in comparison with pristine graphene and C60, showing a large potential in nanophotonic devices. This enhancement is ascribed to the defects formed by etching resulting in a finite band gap in nanostructured graphene.Fil: Sun, Zhenyu. Ruhr-University Bochum. Laboratory of Industrial Chemistry; Alemania;Fil: Dong, Ningning. Chinese Academy of Sciences. Shanghai Institute of Optics and Fine Mechanics. Key Laboratory of Materials for High-Power Laser; China;Fil: Xie, Kunpen. Ruhr-University Bochum. Laboratory of Industrial Chemistry; Alemania;Fil: Xia, Wei. Ruhr-University Bochum. Laboratory of Industrial Chemistry; Alemania;Fil: König, Dennis. Ruhr-University Bochum. Institute for Materials. Department of Mechanical Engineering; Alemania;Fil: Tharamani, Chikka Nagaiah. Ruhr-University Bochum. Analytische Chemie-Elektroanalytik & Sensorik; Alemania;Fil: Sanchez, Miguel Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahía Blanca. Instituto de Física del Sur; Argentina; Universidad Nacional del Sur. Departamento de Física; Argentina; Ruhr-University Bochum. Laboratory of Industrial Chemistry; Alemania;Fil: Ebbinghaus, Petra. Max-Planck-Institut für Eisenforschung GmbH; Alemania;Fil: Erbe, Andreas. Max-Planck-Institut für Eisenforschung GmbH; Alemania;Fil: Zhang, Xiaoyan. Chinese Academy of Sciences. Shanghai Institute of Optics and Fine Mechanics. Key Laboratory of Materials for High-Power Laser; China;Fil: Ludwig, Alfred. Ruhr-University Bochum. Institute for Materials. Department of Mechanical Engineering; Alemania;Fil: Schuhmann, Wolfgang. Ruhr-University Bochum. Analytische Chemie-Elektroanalytik & Sensorik; Alemania;Fil: Wang, Jun. Chinese Academy of Sciences. Shanghai Institute of Optics and Fine Mechanics. Key Laboratory of Materials for High-Power Laser; China;Fil: Muhler, Martin. Ruhr-University Bochum. Laboratory of Industrial Chemistry; Alemania