Reaction of aluminium with alkaline sodium stannate solution as a controlled source of hydrogen

Abstract

The addition of an alkali has been identified as a simple but effective approach for promoting aluminium (Al)/water (H₂O) reactions. However, the use of alkaline solution causes problems with corrosion of system apparatus. We herein report a novel method that can simultaneously address the Al/H₂O reaction kinetics and alkali corrosion problems. Our study found that a combined usage of sodium hydroxide (NaOH) and sodium stannate (Na₂SnO₃) can dramatically improve the hydrogen generation kinetics of the Al–H₂O system. Furthermore, the addition of a small amount of Na₂SnO₃ causes a remarkable decrease of NaOH concentration, which is required for achieving favorable system performance. The factors influencing the hydrogen generation performance of the system were investigated. In the preliminary mechanistic study, the solid samples that were collected at different reaction stages were examined by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Our study showed that the most likely mechanism for the promoting effect of Na₂SnO₃ is the in situ deposition of metallic Sn particles on the Al surface, which act as local inhibitors of the repassivation of Al.