Ni/Fe electrodes prepared by electrodeposition method over different substrates for oxygen evolution reaction in alkaline medium

A series of Ni/Fe electrodes have been prepared by electrodeposition of metal salt precursors on different substrates. The surface morphology, chemical composition and electrochemical characteristics of these electrodes were studied by various physico-chemical techniques such as X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The electrochemical properties of the electrodes were examined by steady-state polarization curves. First, the influence of features such as Ni/Fe composition and type of substrate for the oxygen evolution reaction (OER) were determined by electrochemical techniques in a conventional 3-electrodes cell. The overpotential for the OER is lower for the electrodes with the higher concentrations of Ni. The electrodes with a Ni/Fe composition of 75/25 wt.% electrodeposited on steel mesh and/or 75/25 and 50/50 wt.% on nickel foam result in the most active configurations for the OER. These electrodes were further tested as anodes for alkaline water electrolysis during at least 70 h. In order to understand their activity and stability, the used electrodes were also characterized by SEM and compared to the fresh electrodes. Among the compositions and substrates examined, the Ni50Fe50-Nf electrode exhibited the lowest overpotential (2.1 V) for the OER and the higher stability as anode in an alkaline water electrolysis cell.     

Absence of a charge density wave in the structurally one-dimensional phosphide VP4

The structure of VP₄ has V chains with uniform intrachain separations of 3.25 A1 and interchain distances of 5.26 A1. Since it is reported to be metallic, it might be expected to show charge density wave driven instabilities similar to those observed in other quasi-one-dimensional compounds. However, magnetic susceptibility measurements show no evidence of a charge density wave instability.     

Preparation and properties of reduced bismuth and antimony molybdenum oxides

From molybdenum trioxide-rich, low-melting eutectics formed in the MoO₃-Bi₂O₃ and MoO₃-Sb₂O₃ systems, large crystals of two new reduced bismuth molybdenum oxides and one antimony molybdenum oxide have been grown by the electrolytic reduction of molten salts. These phases are purple with high reflectivity, and show semiconducting behavior. All are orthorhombic with the same systematic absences (corresponding to space groups P_mma or P_mc21). Empirical formulas of these new oxides have the form M′_xMo₂O₅, with x = 0.22 or 0.27 dependent on growth conditions for the bismuth-containing compounds and with x = 0.47 for the anitmony-containing phase.