Highly active cobalt-based catalysts in situ prepared from CoX₂ (X = Cl^-, NO₃^-) and used for promoting hydrogen generation from NaBH₄ solution

Two kinds of CoX₂ (X = Cl^-, NO₃^-) are adopted as the accelerators for the hydrolysis reaction of NaBH₄, which is a promising H₂-supply method for proton exchange membrane fuel cell (PEMFC). In the reactor, the initial H₂ generation is caused by the reaction between pre-infused CoX₂ solution and subsequently imported NaBH₄ solution, and some precipitates are in situ formed on the catalyst bed by this way; and the following H₂ generation is promoted by these precipitates. It is found that there are competitive reactions during H₂ generation from an NaBH₄ to NaOH solution, the anions of CoX₂ are crucial to the reaction pathways, which led to the formation of highly active Co-B or inactive Co(OH)₂. The effects of the CoX₂ concentration, the NaOH concentration, the NaBH₄ feeding rate and the NaBH₄ concentration on H₂ generation performances are discussed and compared.