H-Mg Bond Weakening Mechanism of Graphene-Based Single-Atom Catalysts on MgH2(110) Surface

Abstract

AbstractSolid-state hydrogen storage is gradually becoming an effective way for the large-scale storage and transportation of hydrogen energy. Magnesium hydride (MgH2) has become a promising candidate among solid-state hydrogen storage materials due to its high hydrogen storage density, low cost and good safety. However, ambiguous H-Mg bond weakening mechanism of various catalysts on MgH2 hinders the development of novel catalysts for MgH2 dehydrogenation. To overcome this problem, we applied the model catalyst, single-atom catalyst with accurately characterizable coordination structure, to understand the interaction between catalyst and MgH2 surface through spin-polarized density-functional theory calculation. We constructed heterogeneous interface structures between single-atom catalysts and MgH2 surface including nine kinds of transition metal atoms. The interaction between single-atom catalysts and MgH2 surface has been well explored through bond length, electron localization function, charge density difference and crystal orbital Hamiltonian population, providing the intrinsic information of H-Mg bond weakening mechanism over single-atom catalysts. This work can establish the foundational guide for the design of novel dehydrogenation catalysts.