Synthesis of active electrocatalysts using glycine–nitrate chemistry

Due to sluggish oxygen reduction reactions, development in the solid oxide fuel cell (SOFC) field is stagnant. Two solutions, increasing the active surface or use of precious materials, can stimulate the oxygen reduction kinetics on electrodes. Thus, to gain both these benefits, the present article addressed the synthesis of high surface-area mixed oxide ionic–electronic conductor La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) using chemistry of the propellant glycine–nitrate reaction. In this study, different fuel to oxidant ratios (ψ), 2.0, 2.6, and 3.0 were used to control the exothermicity of reaction and powder properties. The maximum reaction temperature of 1337 K at ψ = 3.0 resulted in coarsened powder. In contrast, comparatively less exothermicity of reaction at ψ = 2.0 resulted in powder with substantial Brunauer–Emmett–Teller surface area of 10.97 m2 g−1, with maximum powder compaction achieved at sintering of 1273 K. With optimal direct current in-plane electrical conductivity of 341 S cm−1, H2-temperature-programmed reduction showed excellent catalytic activity for the sample obtained at ψ = 2.0. The electrochemical performance comparisons of electrodes in two different cell geometries – with and without a gold catalytic current collecting layer (Au–CCCL) – revealed the least polarization and cell resistance in the cell with Au–CCCL. The electrode area specific resistance and cell conductivity using Au–CCCL were 0.097 Ω cm−2 and 0.15 S cm−1, respectively.publishe

Physiochemical properties of combustion synthesized La0.6Sr0.4Co0.8Fe0.2O3-delta perovskite: A role of fuel to oxidant ratio

Abstract The solution combustion synthesis is a novel approach to synthesize the nanocrystalline materials with an unexpectedly high surface to volume ratio. Thus, in present paper, La0.6Sr0.4Co0.8Fe0.2O3-δ powders have been synthesized by solution combustion synthesis route at different fuel to oxidant ratio (ψ) and its effect on different physiochemical properties have been studied. The mode of propagation of combustion reaction changed from smoldering to volume with increasing ψ. The thermal analysis shows that exothermicity increased with ψ resulting into enhanced agglomeration as confirmed from particle size distribution. Typically, the size of agglomerate varies from 0.59 to 1.56 μm. The XRD and FT-IR patterns reveal that the phase pure La0.6Sr0.4Co0.8Fe0.2O3-δ is formed at the ψ=2. The TEM particles size is 25 nm. La0.6Sr0.4Co0.8Fe0.2O3-δ powder shows the higher catalytic activity at about 426 °C. © 2015 Elsevier Ltd.

Implementing a sol-gel route to adjust the structural and dielectric characteristics of Bi and Fe co-doped BaTiO3 ceramics

The present work explores the impact of Fe insertion on the physical properties of Ba0.95Bi0.05Ti1-xFexO3 (x = 0.025, 0.050, and 0.075) prepared via sol gel method. The resulting samples crystallize in the tetragonal structure with space group P4mm and their morphological features point out the variation of the microstructure with Fe content. In turn, the dielectric constant versus temperature plot reveals the existence of two transition phases: the first one is ferroelectric-paraelectric transition phase (TF-P) and the second one is ferroelectric orthorhombic - ferroelectric tetragonal phase (TO-T). Analysis of conductivity curves using Jonscher’s augmented equation (for x = 0.025) and Jonscher’s power law (for x = 0.075) suggests the Non-Overlapping Small Polaron Tunneling (NSPT) model as a conduction mechanism.publishe