Improved hydrogen storage properties of Ti2CrV alloy by Mo substitutional doping

Abstract

Controllable hydrogen release is of great importance to the practical application of hydrogen storage materials. Ti 2 CrV alloy possesses the maximum hydrogen absorption capacity in the Ti–Cr–V series alloys, however, can hardly meet the reversible storage capacity of practical applications due to its stable dihydride. Here we report an advancement in hydrogen storage property of the Ti 2 CrV alloy by Mo partial substitution for Ti. Although the hydrogen absorption kinetics slightly decreased with the increase of Mo content, the Mo substitution alloy achieves an effective hydrogen capacity of 2.23 wt% cutting-off at 0.1 MPa, much higher than Ti 2 CrV alloy (0.8 wt%). It is ascribed that Mo partial substitution for Ti significantly decreased the dihydride stability as well as the enthalpy change value. The cyclic property of Ti 2 CrV alloy drastically decreased, while Mo substitution alloy with smaller FWHM value can maintain 90% storage capacity after 20 cycles. Because lattice strain and distortion of the Ti 2 CrV alloy were decreased by Mo doping. • Mo doping significantly enhanced the effective hydrogen storage capacity of Ti 2 CrV alloy. • Mo doping decreased lattice parameters, FWHM values, and enthalpy change of Ti 2 CrV alloy. • Mo substitution improved the cyclic property of the alloy. • Kinetics and thermodynamics of Mo-doped alloy upon de-/hydrogenation were calculated.