Cobalt borate catalysts for hydrogen production via hydrolysis of sodium borohydride

Cobalt borides are known to be active catalysts in NaBH4 hydrolysis. In situ generation of the active cobalt boride phase in sodium borohydride aqueous solutions is accompanied by formation of cobalt borate whose contribution to the overall catalytic activity of the system has not been studied in detail. In this work an amorphous phase of cobalt borate, which transforms to Co2B2O5 upon crystallization, has been synthesized and analyzed. As-synthesized cobalt borate shows high activity in NaBH4 hydrolysis due to its reduction resulting in catalytically active cobalt-containing phase.

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► Amorphous cobalt borate was synthesized and tested in sodium borohydride hydrolysis.
► Its high activity is due to it reduction by NaBH4 to active cobalt-containing phase.
► Crystallization of cobalt borate and the use of alkaline sodium borohydride solution have a negative influence on the hydrogen generation rate.