Significantly improved hydrogen storage behaviors in MgH2 with Nb nanocatalyst

The study explores the excellent modification effect of Nb nanocatalyst prepared via surfactant assisted ball milling technique (SABM) on the hydrogen storage properties of MgH 2 . Optimal catalyst doping concentration was determined by comparing onset decomposition temperature, released hydrogen capacity, and reaction rate for different MgH 2 −ywt%Nb ( y = 0, 3, 5, 7, 9) composites. The MgH 2 −5wt%Nb composite started releasing hydrogen at 186.7°C and a total of 7.0wt% hydrogen was released in the dehydrogenation process. In addition, 5wt% Nb doped MgH 2 also managed to release 4.2wt% H 2 within 14 min at 250°C and had the ability to absorb 4.0wt% hydrogen in 30 min at 100°C. Cycling tests revealed that MgH 2 −5wt%Nb could retain 6.3wt% H 2 storage capacity (89.2%) after 20 cycles. Dehydrogenation and hydrogenation activation energy values were decreased from 140.51±4.74 and 70.67±2.07 kJ·mol −1 to 90.04±2.83 and 53.46±3.33 kJ·mol −1 after doping MgH 2 with Nb, respectively. Microstructure analysis proved that homogeneously distributed NbH acted as active catalytic unit for improving the hydrogen storage performance of MgH 2 . These results indicate SABM can be considered as an option to develop other nanocatalysts for energy related areas.