An attempt to explain the origin of the vivid red color in precious pink and red corals was undertaken. Raman and IR spectroscopies were applied to characterize white, pink and red corals. The position of the Raman signal near 1500 cm −1 of some corals and pearls was associated by several authors with the presence of the mixture of all-trans-polyenic pigments, containing 6-16 conjugated C C bonds or β-carotenoids. This hypothesis was examined theoretically by performing extensive B3LYP-DFT calculations of vibrational spectra of the model polyenic compounds. The B3LYP/6-311++G * * predicted positions of the dominating Raman mode depend on the number of C C units (Cn parameter) and can be accurately predicted for larger systems from a simple nonlinear fit. The DFT-predicted Raman activities of these modes are extremely sensitive to Cn, and sharply increase with the number of double bonds. This implies a presence of only -two to three polyenes differing slightly in the number of C C units as the source of color in pink and red corals.

It is known that palladium‐based catalysts are initially very active in direct formic acid oxidation but they suffer from fast deactivation caused by a strongly adsorbed CO intermediate. Reactivation of the catalysts involving application of anodic potential may cause palladium dissolution. The aim of the present study is to increase the stability and performance of palladium‐based catalysts in direct formic acid fuel cells (DFAFCs). Preparation and characterization of palladium/multiwalled carbon nanotubes (Pd/MWCNTs) and towards formic acid oxidation via different treatments are described. The catalysts were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry (CV). It was shown that the Pd and Pd–Au MWCNTs supported catalysts after reduction in H2–Ar at 200 °C (R200 treatment) were highly active in formic acid electro‐oxidation, whereas the catalysts after heating in argon at 250 °C (C250 treatment) were inactive. The catalysts after hydrogen treatment have smaller metal particles and better contact with MWCNTs support. CV, simulating reactivation of the catalysts, showed that the Pd catalyst suffers from severe Pd dissolution, whereas for the Pd–Au selective leaching of Pd is considerably slower.

Multi‐walled carbon nanotubes (MWCNTs) supported Pd–Au nanoparticles for electrooxidation of formic acid (FA) are prepared and compared with Pd/MWCNTs in this study. The nanocatalysts are prepared by a polyol method, and characterized using X‐ray diffraction (XRD), thermogravimetry (TGA), SEM, and field emission transmission electron microscope (FE‐TEM). Cyclic voltammetry (CV) is used to examine the catalytic activity towards FA electrooxidation. Controlling the contents of the precursors (PdCl2 and HAuCl4·4H2O), the different weight ratios of Pd–Au can be synthesized to form the various solid solution structures of Pd–Au. TEM image results indicate the average diameter of Pd–Au solid solution particles is about 10–30 nm. The results of electrochemical analysis show that the Au (10 wt.%)/[Pd/MWCNTs (1:9)](90 wt.%) hybrid catalysts exhibit the highest catalytic activity and better stability than that of Pd/MWCNTs in FA electrooxidation. The promoting of Pd‐based catalyst with Au to form solid solution improves the performance of the catalyst in FA electrooxidation. The newly synthesized electrocatalyst is promising for application in direct formic acid fuel cell (DFAFC).

Externally applied magnetic fields have been used in this study to fabricate bamboo-like iron nanowires with or without a layer of Poly(methyl methacrylate) (PMMA). The hybrid PMMA/Fe nanowires were synthesized via hard X-ray synchrotron radiation polymerization with various treatment parameters. The results of XRD show that an oxide layer formed on the surface of the iron nanowires. The Fe2O3 and Fe3O4 phases coexist in the iron nanowires without X-ray irradiation. After X-ray irradiation, the Fe2O3 phase transformed into Fe3O4, which stabilized the iron nanowires. The results of XAS proved this phase transformation. TGA analysis confirmed the thermal properties and solid contents in these specimens. Their ferromagnetic behaviors were examined by magnetic hysteresis measurement, which indicated that the magnetic and structural properties of the nanowires can be manipulated by irradiation treatment. This may lead to a novel synthesis for iron nanowires that can be used in high thermal efficiency hyperthermia therapy

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