Metal nanoparticle assisted growth of assembled zinc oxide nanostructure by low temperature solution phase technique

Herein we report metal nanoparticle directed growth of assembled zinc oxide nanostructures by a facile solution phase route. Si substrates with silver nanoparticles are subjected to low temperature hydrothermal growth. Coulombic attraction resulted in migration of Zn growth species onto Ag nanoparticle surface. SEM analysis revealed preferential nucleation and growth of zinc oxide nanostructures on Ag nanoparticles. Longer reaction period lead to formation of mulberry like assembled ZnO nanostructures. XRD analysis confirmed growth of zinc oxide nanostructures. The formed ZnO nanostructures exhibit well defined band edge PL peak corresponding to excitonic recombination. © 2016 Elsevier B.V.

Sintering behavior and electrochemical performances of nano-sized gadolinium-doped ceria via ammonium carbonate assisted co-precipitation for solid oxide fuel cells

Ultra-fine Gd-doped ceria (GDC) powders were synthesized via co-precipitation using ammonium carbonate as the precipitant. The crystallite size of the resultant GDC powders was measured as ∼33 nm. The dilatometry test of the powder compacts and the relative density measurement of sintered pellets with various sintering temperatures revealed the synthesized nano-GDC powders had superior sinterability compared to commercial GDC powders (e.g., 96% vs 78% in relative density at 1300 °C, respectively). Based on the total conductivity measurement of the co-precipitated GDC via electrochemical impedance spectroscopy, we found there was an optimum sintering temperature range (1300-1400 °C) to achieve both high density and high conductivity due to significant increase in grain boundary resistance at higher temperature (1500 °C). Moreover, the nano-sized and highly sinterable co-precipitated GDC effectively enhanced oxygen reduction reaction at the La0.6Sr0.4Co0.2Fe0.8O3-δ/GDC composite cathode due to increase in active reaction sites as well as enhanced phase connectivity in 3D-bulk at lower sintering temperatures. © 2016 Elsevier B.V. All rights reserved.