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Effect of stabilizer on the catalytic activity of Kobalt(0) Nanoclusters catalyst in the hydrolysis of Sodium Borohydride

Koçak, Ebru
The development of new storage materials will facilitate the use of hydrogen as a major energy carrier in near future. Among the chemical hydrides used as hydrogen storage materials for supplying hydrogen at ambient temperature, sodium borohydride seems to be an ideal one because it is stable under ordinary conditions and liberates hydrogen gas in a safe and controllable way in aqueous solutions. However, self hydrolysis of sodium borohydride is so slow that requires a suitable catalyst. This work aims the use of water dispersible cobalt(0) nanoclusters having large portion of atoms on the surface as catalyst for the hydrolysis of sodium borohydride. In-situ formation of cobalt(0) nanoclusters and catalytic hydrolysis of sodium borohydride were performed starting with a cobalt(II) chloride as precursor and sodium borohydride as reducing agent and substrate in the presence of a water soluble stabilizer. As stabilizer, water soluble polyacrylic acid as well as hydrogen phosphate ion were tested. Cobalt(0) nanoclusters were characterized by using all the available analytical methods including FT-IR, TEM, XPS, UV-visible electronic absorption spectroscopy. The kinetics of cobalt(0) nanoclusters catalyzed hydrolysis of sodium borohydride were studied depending on the catalyst concentration, substrate concentration, stabilizing agent concentration and temperature.