Heteroatom sulfur exploration for enhancing MgH2 dehydrogenation: A theoretical and experimental analysis.

High operating temperatures and sluggish kinetics constrain the commercial application of magnesium-based hydrogen storage materials. To overcome these drawbacks, this work investigates heteroatom sulfur as a catalyst to improve the dehydrogenation of MgH 2 using density functional theory (DFT) and experimental validation. Heteroatom sulfur can influence the dehydrogenation of MgH 2 by modulating interfacial carbon-magnesium interactions and substituting surface hydrogen sites. In particular, DFT calculations reveal that sulfur functional groups facilitate charge transfer and significantly reduce the energy barrier of MgH 2 by 0.32 eV–1.59 eV. Substitution of sulfur atoms at surface hydrogen sites of MgH 2 notably improves dehydrogenation by weakening the Mg–H bond and enabling a sulfur-assisted two-step dehydrogenation mechanism. Experimental results further confirm these theoretical findings. The MgH 2 /900C–20SO 2 sample exhibits that the peak dehydrogenation temperature and the onset dehydrogenation temperature were 19.8 °C and 64 °C lower than that of pure MgH 2 , and a significant reduction in activation energy from 134.52 kJ mol−1 to 92.12 kJ mol−1. This research provides a comprehensive understanding of the catalytic effects of heteroatom sulfur on MgH 2 and offers crucial theoretical and practical insights for the development of more efficient magnesium-based hydrogen storage systems. [Display omitted] • The catalytic mechanism of heteroatom sulfur on the dehydrogenation of MgH 2 was investigated. • It was demonstrated that heteroatom sulfur can enhance the dehydrogenation of MgH 2. • Oxidized sulfur functional groups can weaken Mg–H bonds and facilitate charge transfer. • Some sulfur atoms form MgS in situ with Mg, triggering a two-step dehydrogenation. [ABSTRACT FROM AUTHOR]