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To characterize complex, three‐dimensional nanostructures, modern microscopy techniques are needed, such as electron tomography and focused ion beam (FIB) sectioning. The aim of this study was to apply these two techniques to characterize TiO2 nanotubes in terms of their size, shape, volume, porosity, geometric surface area, and specific surface area (SSA). For these experiments, titania nanotubes were fabricated by means of the electrochemical oxidation of titanium at a voltage of 20 V for 2 hr followed by heat treatment at 450°C for 3 hr to change the amorphous structure into a crystalline anatase structure. The quantitative data obtained from the FIB and electron tomography reconstructions show a high similarity in porosity and some differences in SSA. These might be the result of differences in resolution between the two reconstruction techniques. The resolution of electron tomography method is better than FIB sectioning that might influence on quantitative data like SSA.FIB sectioning allows to visualize 3D structure of much larger volume than electron tomography method.FIB sectioning and electron tomography are complementary techniques for characterizing nanostructured materials such as nanotube layers. [ABSTRACT FROM AUTHOR]

In this article, we present a wet ultrasonochemical synthesis of nanocrystalline TiO2 powders in the anatase form in ethanol solution and their surface decoration using uniformly dispersed Ag metallic nanoparticles of about 4 nm at concentration of n = 0.5 to 2.5 wt% and those of 10–20 nm larger at a higher concentration than 1 wt%. The structure of the prepared composites was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman and X-ray photoelectron spectroscopy (XPS). Optical properties were determined using UV-vis spectroscopy. Six polymer solar cells with modification by an TiO2/n-Ag hole transporting layer were manufactured and studied under AM 1.5G-simulated solar illumination (100 mW cm−2). The best performance was obtained for a device with the ITO/(PEDOT:PSS):1.5%Ag in TiO2/P3HT:PCBM/Al architectures. Under these conditions, a PCE of 2.07% with open circuit voltage Voc = 0.612 V, short circuit current density Jsc = 5.94 mA cm−2, and fill factor FF = 0.57 was achieved. Additionally, devices were tested by electrochemical impedance spectroscopy under illumination and a well-fitted equivalent circuit was proposed. Finally, our idea of the linkage of TiO2/n-Ag with PEDOT:PSS and P3HT in the constructed devices taking into account the amount of Ag in TiO2 was proposed. [ABSTRACT FROM AUTHOR]

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO2 in the presence of WO3 at 1550 °C in argon resulted in the formation of WxC-β-SiC nanocomposite powders with significant variations in particle morphology and content of WxC-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite WxC-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest WxC crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved. [ABSTRACT FROM AUTHOR]

Anatase phase formation in TiO2 films obtained by atomic layer deposition (ALD) is investigated. At growth temperature close to 200 °C, the anatase phase of TiO2 originates from crystalline seeds formed in an amorphous layer. These seeds, formed in the initial stages of a film growth, allow an expansion of the anatase phase in the amorphous parts and their transformation. This expansion occurs either during a further growth process or during a post-deposition annealing at relatively low temperatures (160–220 °C). The process of a lateral expansion of the anatase phase within the amorphous one was found to be thermally activated with an activation energy of 1.5 eV. [ABSTRACT FROM AUTHOR]

A ternary TiNiCu shape memory alloy is subjected to high‐pressure torsion (HPT) followed by post‐deformation annealing (PDA) to study the effect of Cu (5 at%) on amorphization after HPT processing and to investigate the microstructural evolution and shape memory effect (SME) after PDA. The results show that even after 20 revolutions the ternary alloy contains nanocrystalline areas and the microstructure is not fully amorphous. An easier martensite‐to‐austenite transformation and minor remaining austenite in the ternary alloy are responsible for suppressing amorphization. Post‐deformation annealing at 673 K provides nanocrystalline microstructures containing an R‐phase with a minor martensitic B19' phase in the ternary alloy. The SME of this alloy after PDA is not as satisfactory as that of the binary alloy processed through similar conditions because of the existence of a high volume fraction of the R‐phase. However, the total recovered strain of the ternary alloy after PDA for 30 min has a maximum value of 6.5%. [ABSTRACT FROM AUTHOR]