Progress of Cryogenics and Isotopes Separation

NIOBIUM OXIDE CATALYSTS OBTAINED BY DC MAGNETRON SPUTTERING FOR PEM ELECTROLYSIS APPLICATION

Daniela Ion-Ebrasu^1*, Stanica Enache¹, Alexandru Rizoiu¹, Mihaela Filip², Silviu Preda², Mihai Varlam¹, Victor Fruth², Ioan Stefanescu¹

¹National Research and Development Institute for Cryogenics and Isotopic Technologies - ICSI Rm. Valcea, Uzinei Street no. 4, P.O. Box Râureni 7, 240050, Râmnicu Vâlcea, Romania

²IlieMurgulescu Institute of Phisical Chemistry, Romanian Academy, P.O. Box 12-194, 060021, Bucharest, Romania

abstract

Proton exchange membrane (PEM) water electrolysis is seen as one of the most efficient and simple way to obtain high purity hydrogen. A major drawback in these systems is the catalysts long term stability in aqueous media. One way to improve that is to use niobium oxides as catalytic support since they have enhanced catalytic stability and high corrosion resistance to various acid-catalyzed reactions such as sulfonated radicals in the form of proton exchange membranes.

In this work we show that nano-sized niobium-niobium oxides can be obtained by DC magnetron sputtering in Ar atmosphere, without using oxygen during deposition. Residual contamination with oxygen renders the films composite, consisting of niobium-niobium oxide conglomerates resembling to a core-shell structure. The catalytic activity of the top niobium-oxide layer is investigated by voltammetric methods whereas the structural, electrical and optical properties are studied by XRD, frequency dependent impedance and UV-Vis transmission techniques, respectively.

Keywords: Electrolysis, niobium, DC sputtering.