Effect of Mg–Nb Oxides on Hydrogen Sorption Kinetics of Ball–milled MgH2

Abstract

Abstract Addition of Mg–Nb oxides (e.g., MgNb2O6, Mg4Nb2O9 and Mg3Nb6O11) ameliorates H2 absorption/desorption kinetics of MgH2 as demonstrated in the current issue. H2 desorption and absorption rates of the ball–milled MgH2 are evidently temperature-dependent point out that the prior rate increases with increasing temperature (593 to 673 K) and vice versa. Among the tested samples, MgH2 with Mg3Nb6O11 nanoparticles showed superior performance. The Johnson–Mehl–Avrami equation was employed to construct H2 desorption curves as well as find out reaction rate constants at different temperatures. The Arrhenius equation was fitted in the context to estimate activation energy and that of the ball–milled MgH2 and MgH2/Mg3Nb6O11 mixtures, for example, obtained 127 and 88 kJmol–1, respectively. Besides, a novel experimental setup combining a hydrogen detector with a differential scanning calorimeter was used to confirm the H2 desorption properties of the ball-milled nanoparticles discussed based on the kinetic argument.