Fig. 1. Schematic diagram of hydrolysis reaction device.

Fig. 2. Hydrolysis kinetic curves of the MgH2 in different chloride solutions (a) and sulfate solutions (b) at 298 K. Hydrolysis kinetic curves of the MgH2 at different temperatures in Fe2(SO4)3 solution (c) and their Arrhenius plot (d).

Fig. 3. XRD patterns of MgH2 hydrolysis products in (a) MgCl2 solution; (b) ZnCl2 solution; (c) CuCl2 solution; (d) FeCl3 solution.

Fig. 4. SEM images of the integrated MgH2 particles in (a) pure water, (b) MgCl2 solution and (c) FeCl3 solution after 30 min reaction; the surface of MgH2 particles in (d) pure water, (e) MgCl2 solution and (f) FeCl3 solution after 30 min reaction.

Fig. 5. Schematic illustration of the mechanism for the hydrolysis of MgH2 in (a) pure water and (b) M x+ solution.

Fig. 6. (a) Hydrolysis kinetic curves of the MgH2 in different Mg2+ solutions and pure water at 298 K. (b) Hydrolysis kinetic curves of the MgH2 in MgCl2 solution at different temperatures. The inset is their Arrhenius plot.

Fig. 7. The water utilization rate of MgH2 hydrolysis in the (a) 0.5 M MgCl2, MgSO4 and Mg(CH3COO)2 solutions, and (b) the mixture solutions of 0.5 mol L-1 MgCl2, 0.5 M MgCl2 + 0.1 M Mg(CH3COO)2, 0.5 M MgCl2 + 0.1 M MgSO4, and (c) the mixed solutions of different concentration ratios for MgCl2 and MgSO4 at 298 K. The solution volume is 10 ml. (d) the power function model Eq. (3) fitting curve between H2O utilization rate and solution volume for 0.5 M MgCl2 + 0.05 M MgSO4 solution.

Fig. 8. (a) Proposed hydrogen generation system based on the hydrolysis of MgH2 in mixed 0.5 M MgCl2 and 0.05 M MgSO4 solution with continuous feeding of MgH2; (b) The solid curve: simulated system H2O utilization rate at different solution volume based on Eq. (3). The dashed line: the 100 % H2O utilization rate.

Fig. 9. SEM images of hydrolysis products in the mixed solutions of (a) 0.5 M MgCl2 + 0.05 M MgSO4, (b) 0.5 M MgCl2 + 0.1 M MgSO4, (c) 0.5 M MgCl2 + 0.5 M MgSO4, (d) 0.5 M MgCl2 + 0.1 M Mg(CH3COO)2.