Synergistic effects of amorphous carbon and MgS on hydrogen storage properties in MgH2

Abstract

To improve the thermodynamic stability and kinetic performance of magnesium-based hydrogen storage materials, a co-sintering assisted hydrogenation ball milling method was adopted to successfully prepare MgH₂-CBD composite with dibenzyl disulfide (CBD) as an additive. Through various characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC), the microstructure, phase composition and hydrogen storage performance of the materials were systematically analyzed. The results show that the in situ generated MgS and amorphous carbon are uniformly dispersed in the magnesium matrix, significantly enhancing the hydrogen absorption and desorption kinetic performance of the material. Under the conditions of 548 K and 3 MPa, the MgH₂-CBD with a molar ratio of 5 : 1 composite material achieves a hydrogen absorption capacity of 6.523 wt% within 3600 s, which is significantly higher than the 4.857 wt% of pure MgH₂. Under the conditions of 623 K and 0.01 MPa, its hydrogen desorption capacity reaches 5.309 wt%, far exceeding the 2.428 wt% of pure MgH₂. In addition, the initial desorption temperature of the composite material is reduced from 639 K to 575 K, and the dehydrogenation activation energy is decreased from 159.7 kJ mol⁻¹ to 117.9 kJ mol⁻¹. The research indicates that the synergistic catalytic effect of MgS and amorphous carbon effectively inhibits the agglomeration behavior of magnesium particles, providing abundant reaction interfaces and hydrogen diffusion channels, thereby significantly improving the comprehensive hydrogen storage performance of Mg-based hydrogen storage materials.