Structure-controlled synthesis of gold nanostructures (AuNSs) induced by temperature in a nonaqueous urea-choline chloride deep eutectic solvent (DES) is reported. Modulation of nanostructures with welldefined structures and shapes is obtained by simply varying the reaction temperature. The supramolecular soft template provided by the DES structure and its viscosity at different temperatures drives directed growth of crystalline gold and self-assembly producing star-shaped AuNSs. Additionally, the effect of AuNS shape and surface area on their catalytic activity towards the reduction of hydrogen peroxide (H 2 O 2 ) has been tested. With the advantage of their high surface area and presence of highindex facets in the edge of the star arms, the star-shaped nanostructures showed superior electrocatalytic activity than other morphologies. The use of DES as a green chemistry platform for the synthesis of shape-controlled Au nanostructures with high catalytic properties may offer new avenues for fuel cell and biosensor applications.

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Preparation of electrodes modified with poly(3,4‐ethylenedioxythiophene) nanowires, PEDOT‐nw, was optimized using nanoparticles of dispersed Pt, Pt‐np, to be tested for HCOOH electro‐oxidation. The PEDOT‐nw is electrosynthesized directly on the working electrode, using mesoporous silica as template, by cyclic voltammetry from a 0.01 mol L−1 monomer + 0.1 mol L−1 tetrabutylammonium hexafluorophosphate solution in acetonitrile, on the Pt|PEDOT|mesoporous silica template previously modified electrodes. Using SEM, the presence of PEDOT nanowires with 20 to 25 nm in diameter was verified. In addition, its p‐doping response is about 500 times larger than that obtained on the bulk polymer, maintaining full reversibility of the process. The subsequent electrochemical insertion of Pt‐np and formation of Pt‐np with average diameter of about 20 nm, checked by TEM, demonstrated that the catalytic activity of this nanostructured electrode remarkably enhanced HCOOH electro‐oxidation. The obtained current is up to 2 orders of magnitude higher than previously reported in similar studies, using a much smaller amount of Pt and with a potential decrease greater than 100 mV. Thus, we have at our disposal a simple, inexpensive, and highly reproducible way to prepare in situ nanostructured electrodes using just electrochemical techniques, which can be useful on all the applications of these devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44723.

Molecular relaxations of chitosan films have been investigated in the wide frequency range of 0.1 to 3 × 10(9) Hz from -10 °C to 110 °C using dielectric spectroscopy. For the first time, two high-frequency relaxation processes (in the range 10(8) to 3 × 10(9) Hz) are reported in addition to the low frequency relaxations α and β. These two relaxation processes are related to the vibrations of OH and NH2/NH3(+), respectively. The high-frequency relaxations exhibit Arrhenius-type dependencies in the temperature range 10 °C to 54 °C with negative activation energy; this observation is traceable to hydrogen bonding reorientation. At temperatures above the glass transition temperature (54 °C), the activation energy changes from negative to positive values due to breaking of hydrogen bonding and water loss. Upon cooling in a sealed environment, the activation energies of two relaxation processes are nearly zero. FTIR and XRD analyses reveal associated structural changes upon heating and cooling. These two new high-frequency relaxation processes can be attributed to the interaction of bound water with OH and NH2/NH3(+), respectively. A plausible scenario for these high-frequency relaxations is discussed in light of impedance spectroscopy, TGA, FTIR and XRD measurements.