Synthesis of activated ferrosilicon-based microcomposites by ball milling and their hydrogen generation properties

Ferrosilicon was activated toward hydrogen generation by processing using ball milling. An activation energy of 62 kJ/mol was determined for the reaction of ball-milled ferrosilicon powder with sodium hydroxide solution, which is ca. 30 kJ/mol lower than that previously reported for unmilled ferrosilicon. A series of composite powders were prepared by ball milling ferrosilicon with various additives. Three different classes of additives were employed: salts, polymers and sugars. The effects of these additives on hydrogen generation from the reaction of ferrosilicon with 2 wt.% aqueous sodium hydroxide were investigated. It was found that composites formed of ferrosilicon and sodium chloride, potassium chloride, sodium polyacrylate, sodium polystyrene sulfonate-co-maleic acid or fructose showed reduced induction times for hydrogen generation compared to that observed for ferrosilicon alone, and all but fructose also led to an increase in the maximum hydrogen generation rate. In light of its low cost and toxicity and beneficial effects, sodium chloride is considered to be the most effective of these additives for activating ferrosilicon toward hydrogen generation.