H2 generation kinetics/thermodynamics and hydrolysis mechanism of high-performance La-doped Mg-Ni alloys in NaCl solution—A large-scale and quick strategy to get hydrogen.

• As-cast 15La generate 770mL· g ⁻¹ H 2 at 291 K and 953mL· g ⁻¹ H 2 within 240 min at 321 K. • HEBM 5La generates 670mL· g ⁻¹ H 2 within 5 min and 824mL· g ⁻¹ H 2 within 20 min at 291 K. • Hydrolysis H 2 generation mechanism based on nucleation & growth has been proposed. • Low initial nucleation rate and fully growth up of Mg(OH) 2 determine high capacity. In this work, La-doped Mg-Ni multiphase alloys were prepared by resistance melting furnace (RMF) and then modified by high-energy ball milling (HEBM). The hydrolysis H 2 generation kinetics/thermodynamics of prepared alloys in NaCl solutions have been investigated with the help of nonlinear and linear fitting by Avrami-Erofeev and Arrhenius equations. Combining the microstructure information before and after hydrolysis and thermodynamics fitting results, the hydrolysis H 2 generation mechanism based on nucleation & growth has been elaborated. The final H 2 generation capacities of 0La, 5La, 10La and 15 La alloys are 677, 653, 641 and 770 mL· g ⁻¹ H 2 in 240 min at 291 K, respectively. While, the final H 2 generation capacities of HEBM 0La, 5La, 10La and 15 La alloys are 632, 824, 611 and 653 mL· g ⁻¹ H 2 in 20 min at 291 K, respectively. The as-cast 15La alloy and HEMB 5La alloy present the best H 2 production rates and final H 2 production capacities, especially the HEBM 5La can rapidly achieve high H 2 generation capacity (670 and 824 mL· g ⁻¹ H 2) at low temperature (291 K) within short time (5 and 20 min). The difference between the H 2 generation capacities is mainly originated from the initial nucleation rate of Mg(OH) 2 and the subsequent processes affected by the microstructures and phase compositions of the hydrolysis alloys. Relative low initial nucleation rate and fully growth of Mg(OH) 2 nucleus are the premise of high H 2 generation capacity due to the hydrolysis H 2 generation process consisted by the nucleation, growth and contacting of Mg(OH) 2 nucleus. To utilization H 2 by designing solid state H 2 generators using optimized Mg-based alloys is expected to be a feasible H 2 generation strategy at the moment. [Display omitted] [ABSTRACT FROM AUTHOR]