In this work, a simple non-template one-step method for the synthesis of 2.0-2.5 nm palladium nanoparticles encapsulated into a polypyrrole shell via direct redox reaction between palladium(II) acetate and pyrrole in acetonitrile medium is described. Palladium nanoparticles are found to be able to self-organize into spherical Pd/PPy composites. The size of the Pd/PPy composite particles and Pd content in the composite depend strongly on the concentration of the palladium salt component. The combination of elemental CHNS and thermogravimetric (TGA) analysis was used to determine a high (∼40 wt %) content of palladium, which is in a good agreement with EDX data. The process of Pd/PPy composite formation was studied with the use of UV-vis spectroscopy and AFM spectroscopy. Properties of the obtained material were characterized by means of FTIR, XPS, XRD, SEM, and TEM techniques.

International audienceIn the present article, we report the synthesis of titanate nanotubes and nanoribbons with controlled morphology, structure, and chemical composition depending on the main parameters of the synthesis. Hydrothermal processing time, grain size of the precursor, type of agitation, and acid treatment were investigated, and the principal controversies mentioned in the literature such as nanotube crystallographic structure, their chemical composition, and acid treatment impact are discussed. These controversies may be due to the heterogeneities present in all the samples and are rarely considered in the literature. These nanostructures were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy. A careful desummation of the first XRD peaks revealed the presence of both nanosheets and nanotubes and allowed an estimation of their proportions. In addition, the titanate nanotube section is observed to be not perfectly circular but rather elliptic. Moreover, the first acid treatment effect is shown to remove any trace of sodium and structural water. The second effect of acid washing is a morphological evolution