Design of Al-Fe Alloys for Fast On-Board Hydrogen Production from Hydrolysis

Abstract

not Available.

Production of hydrogen, active zerovalent iron and ferroferric oxide octahedron by alkaline etching Al–Fe alloys

“…Therefore, the concentrations of Al and IMCs in the Al-Fe alloys account for hydrogen generation rate in an order of Al-Fe10 > Al-Fe20 > Al-Fe50. This trend is in agreement with the Al-Fe alloys with Fe concentrations of 1%, 3% and 6% where the lowest Fe-containing alloy achieved the highest rate of hydrogen generation in 2.5 M NaOH [17].…”

“…The protruded items of 1-2 m wide and 10-100 m long were most likely Al 13 Fe 4 , despite that no appreciate amounts of Al 13 Fe 4 were captured. It was reported that Al 3 Fe and Al 2 Cu precipitated along grain boundaries from their respective Al-Fe and Al-Cu alloys, creating defects and cracks during the alkaline etching process [17,25]. Al 3 Fe from Al-Fe alloy was identified in an elliptical shape of 1-2 m long and 0.1-0.4 m wide [17].…”

“…The rate of hydrogen generation by the hydrolysis of Al-based alloys is determined by the type and concentration of alloyed metals, NaOH concentration and the alloy's particle size [17,47,49,50]. In general, galvanic corrosion may develop when two types of metals with different corrosion potential are contacted.…”

“…Increasing the difference in the corrosion potential between the two metals, the corrosion rate of more active metal increases. Al-Fe alloys consist of three phases: Al, Fe and Al-Fe intermetallic compounds (Al 2 Fe, Al 3 Fe, Al 5 Fe 2 , Al 13 Fe 4 ) and the concentrations of Fe and the intermetallic compounds (IMCs) are the major factors influencing hydrogen generation rate via galvanic and intergranular corrosions [17]. Eom et al demonstrated that Al-Fe IMCs are more resistant to the hydrolysis than Al metal and the higher concentration of IMCs in Al-Fe alloys are dependent on Fe concentration (Fig.…”

“…The cost of Al metal hydrolysis for hydrogen production is much lower (US$3/kg) [15] than that of NaBH 4 method while the byproduct can be recycled through Hall-Heroult process [16]. Most importantly, Al has relatively high hydrogen production capacity (0.11 kg H 2 per kg Al) [17]. An electric car powered by hydrogen fuel cells with a driving distance of 400 km just requires 4 kg of hydrogen, corresponding to 36 kg Al metal [18].…”