H₂ Production of As‐Cast Multialloying Mg‐Rich Alloys by Electrochemical Hydrolysis in NaCl Solution

Abstract

To adjust the hydrolysis H2 generation properties of as‐cast Mg–10wt%Ni (Mg10Ni) alloy, intermediate alloys Mg–Ce and Mg–La are introduced to prepare Mg9Ni10Ce and Mg9Ni10La. The H2 generation thermodynamics are investigated based on microstructures, electrochemical polarization properties, and fitted information of hydrolysis curves by Avrami–Erofeev and Arrhenius equations. The results indicate that Ni/La/Ce alloying elements can modify the microstructures of the Mg matrix by forming active phases Mg2Ni and Mg12Ce or Mg17La2, phase boundaries, and α‐Mg solid‐solution. The H2 generation capacities of Mg10Ni, Mg9Ni10Ce, and Mg9Ni10La are 532, 511, and 444 mL g−1 with 0.63, 0.68, and 0.59 conversion yields in 2.5 h at 293 K in NaCl solution. The conversion yields of Mg10Ni, Mg9Ni10La, and Mg9Ni10Ce can be promoted to 0.88, 0.91 and 0.99 at 308 K with 741, 756 and 690 mL g−1 H2, respectively. Due to the high content of eutectic structure and active phase as well as the stronger electrochemical hydrolysis tendency, the modification effect of La is better than Ce. The microstructure–property relationship and thermodynamics built herein can provide an effective strategy to regulate Mg‐based alloys to achieve a high conversion yield and rapid rate by electrochemical hydrolysis H2 generation.

Modeling hydrolysis kinetics of dual phase α-Mg/LPSO alloys

“…This new model may help analysing hydrolysis results in future works. Especially since Mg alloy design is a common strategy for hydrogen production from Mg based materials and researchers struggle at modeling the whole data range of the reaction kinetics [16,[31][32][33][34][35][36][37][38].…”