Unraveling the corrosion kinetics of gallium- aluminum for efficient hydrogen production from water at zero CO2 emission

초록

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 chlo-ride (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 degrees C), further maintained the long-term stability of 92.3% for about 25 h at 35 degrees 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 cir-culation 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.(c) 2022 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

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