Abstract
Hydrogen (H2) generation via metal hydrolysis is a promising eco-friendly technique that has been widely accepted by the industrial sector. This work mainly focuses on stable H2 production through a simple surface-etching process by hydrofluoric acid (HF) to expel the passive aluminum oxide (Al2O3) layer. The HF-treated aluminum (Al) metal is allowed to react with liquid gallium (Ga) adopting Al–Ga hydrolysis in three different electrolytic solutions of hydrochloric acid (HCl), sodium hydroxide (NaOH), and neutral sodium chloride (NaCl) solutions (named Ga-Al-water reaction). Significantly, the high H2 productivity of 95.9% achieved in 0.4 M NaCl solution at various temperatures (35–65 °C), further maintained the long-term stability of 92.3% for about 25 h at 35 °C. Density functional theory (DFT) calculations confirm the spontaneity of the initial Al oxidation by the Ga liquid metal, leading to spontaneous water-splitting reactions. Furthermore, the Ga catalyst was recovered even after five reusability cycles without productivity decay. This method yields aluminum hydroxide (Al(OH)3) as reaction byproducts which could enable resource circulation in pharmaceutical, textile dyeing, and various chemical industries. This study demonstrates the feasibility of the new Ga-Al-water system with an enhanced Ga–Al contact for large-scale H2 production from seawater and portable fuel cell devices.
Published Version
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