Novel synthesis of nickel–iron hexacyanoferrate nanoparticles and its application in electrochemical sensing

Characterization of Multiphase Oxide Layer Formation on Micro and Nanoscale Iron Particles

The article presents a detailed study and characterization of the oxide layers on the surface of iron particles of various sizes. Ten iron samples with a size range from a few nm to 50 µm were studied in detail using SEM, TEM, XRD, and TGA analysis. The composition of the multiphase oxide layers on the powder surface was investigated. The main components of the oxide layer were FeO, Fe3O4, and Fe2O3. By the obtained data, a model for the calculation of a multiphase oxide layer thickness on the surface of iron particles was proposed. The proposed model was validated and can be used for the characterization and certification of micro– and nanoscale iron particles.

A Heavily Surface-Doped Polymer with the Bifunctional Catalytic Mechanism in Li-O2 Batteries

The application of conducting polymers (CPs) in energy storage systems is greatly limited by insufficient reversibility and stability. Here, we successfully incorporated functionalized dopants (Fe(CN)63- [FCN] and PO43- ions) in CPs matrixes to achieve a preferable electrochemical performance. A stable cation inserting/expulsing behavior of surface-doped polycarbazole (PCz) is demonstrated in our work, where doping levels and semiconductor properties of PCz are effectively controlled to adjust their redox properties and stability. With carbon nanotube (CNT) films as the substrate, the CNT/PCz:FCN composite is initially adopted as a free-standing catalytic electrode in Li-O2 cells. The molecule-level dispersed FCN dopants on the surface can work as bifunctional redox mediators on the charge-discharge process. Thus, this composite can not only achieve a low charge plateau of 3.62 V and a regular growth of capacities from 1,800 to 4,800 mAh/gCNT, but also maintain the most of charge voltages under 4.0 V for 150 cycles.