Preparation and Characteristics of Novel Cobalt Oxide Catalysts for Hydrogen Generation from Metal Borohydride Solution

Abstract

For the first time, a high performance cobalt oxide catalyst for hydrogen generation has been developed in a cost-effective way. The novel cobalt oxide catalyst was prepared by microwave-assisted thermal oxidation of cobalt metal. Microwave heating produced cobalt oxide from cobalt metal powder within 10 min through oxidation and consolidation simultaneously. An as-synthesized cobalt oxide catalyst (a centimeter-sized chip) has revealed high activity for the catalytic hydrolysis of sodium borohydride (NaBH4) showing a maximum hydrogen evolution rate of 6,000 mL/min-g from an aqueous solution containing 20 wt% of NaBH4+5 wt% of sodium hydroxide (NaOH) under room temperature. Furthermore, a powder sample of cobalt oxide showed a maximum hydrogen evolution rate of 13,412 mL/min-g under the same conditions as above. The hydrogen evolution rates were affected by temperature and concentrations of NaBH4 and NaOH as well as the amount of the cobalt oxide catalyst. Based on X-ray photoelectron spectroscopy and X-ray diffraction studies, the structural transformations of the catalyst were observed after catalytic hydrolysis of NaBH4.