Facile Synthesis of Polyindole/Ni Zn FeO ( = 0, 0.5, 1) Nanocomposites and Their Enhanced Microwave Absorption and Shielding Properties.

The present work reports the fabrication of polyindole (PIN)/Ni Zn FeO ( = 0, 0.5, 1) nanocomposites as efficient electromagnetic wave absorbers by a facile in situ emulsion polymerization method for the first time. The samples were characterized through Fourier transform infrared spectroscopy, UV-vis spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, high-resolution transmission electron microscopy, and vibrating sample magnetometry.

Cobalt-Doped BaInO Brownmillerites: An Efficient Electrocatalyst for Oxygen Reduction in Alkaline Medium.

A series of compounds with cobalt doping in the indium site of BaInO brownmillerites exhibited excellent oxygen reduction activity under alkaline conditions. Doping (25%) retains the brownmillerite structure with disorder in the O3 site in the two-dimensional alternate layer along the plane. Further substitution of cobalt in the indium site leads to the loss of a brownmillerite structure, and the compound attains a perovskite structure.

Room-Temperature Activation of CO by Dual Defect-Stabilized Nanoscale Hematite (FeO ): Concurrent Role of Fe and O Vacancies.

We demonstrate that synthetically controlled concurrent stabilization of Fe and O vacancy defects on the surface of interbraided nanoscale hematite (FeO ) renders an interesting surface chemistry which can reduce CO to CO at room temperature (RT). Importantly, we realized a highly enhanced output of 410 μmol h g at RT, as compared to that of 10 μmol h g for bulk hematite. It is argued based on the activity degradation under cycling and first principles density functional theory calculations that the excess chemical energy embedded in the defect-stabilized surface is expended in this high-energy conversion process, which leads to progressive filling up of oxygen vacancies.

Nitrogen Doping in Oxygen-Deficient CaFeO: A Strategy for Efficient Oxygen Reduction Oxide Catalysts.

Oxygen reduction reaction (ORR) is increasingly being studied in oxide systems due to advantages ranging from cost effectiveness to desirable kinetics. Oxygen-deficient oxides like brownmillerites are known to enhance ORR activity by providing oxygen adsorption sites. In parallel, nitrogen and iron doping in carbon materials, and consequent presence of catalytically active complex species like C-Fe-N, is also suggested to be good strategies for designing ORR-active catalysts.

Effect of B site coordination environment in the ORR activity in disordered brownmillerites Ba2In2-xCexO5+δ.

Ba2In2O5 brownmillerites in which the In site is progressively doped with Ce exhibit excellent oxygen reduction activity under alkaline conditions. Ce doping leads to structural changes advantageous for the reaction. Twenty-five percent doping retains the ordered structure of brownmillerite with alternate layers of tetrahedra and octahedra, whereas further increase in Ce concentration creates disorder.