Hydrogen storage properties of Nd5Mg41Ni alloy improved by GO

Abstract

Due to the high activation energy required for the decomposition of Mg metal hydrides, it can be decomposed into magnesium and H2 when the external temperature reaches 350 °C. In this paper, Nd5Mg41Ni + x wt.% GO (x = 0–4) composites were obtained by planetary ball milling the alloy with GO for 10 h. The alloy has Nd5Mg41, NdMg3, NdMg12 and Mg2Ni phase, and the main phase is Nd5Mg41 phase. The time required for the alloy phase structure composite material to reach the maximum hydrogen desorption capacity of 95 % is 20, 23, 18, 17 and 18 min, and the calculated hydrogen desorption activation energy Ea values are 99.9, 98.1, 95.6, 89.9 and 95.7 kJ/mol H2, the ΔHde of the composites are 77.57, 76.40, 73.48, 70.77 and 81.2 kJ/mol H2, respectively. The alloy particles are embedded in the layered GO to form a special microstructure of the nanocrystalline GO embedded nanocrystalline alloy, which makes the composite material easier to adsorb hydrogen molecules and promotes the dissociation of hydrogen molecules and the diffusion of hydrogen atoms. However, the excessive addition of GO leads to excessive GO coating alloy particles, which hinders the diffusion of hydrogen atoms. The agglomeration of alloy particles leads to the increase of hydrogen desorption enthalpy of the alloy.

Keywords

• Ball milling
• GO
• Mg-based alloy
• Hydrogen storage
• Kinetic