Density functional theory study of hydrogenation mechanism in Fe-doped Mg(0001) surface

Dehydrogenation Properties of Magnesium Hydride Loaded with Fe, Fe−C, and Fe−Mg Additives

“…Although it is difficult to generalize on the role of metal oxide additives with the present additive Fe, we believe that the Fe additive helps to decrease the hydrogen diffusion pathways by fragmentation of particles for the improved dehydrogenation of MgH 2 , rather than any intrinsic catalytic effect offered by the formed mixed metal phase Mg 2 FeH 6 . In the literature, the mechanism of Fe addition to MgH 2 has been explained by various researchers on the basis of substitution models. However, the present observations support the view that only pure Fe behaves as an active additive.…”

“…Whereas most of the experimental studies do not confirm the substitution of Fe in the lattice of MgH 2 , various theoretical studies suggest that Fe substituted Mg/MgH 2 surfaces actively influence the Mg–H interaction. The DFT calculations by Wu et al . suggested the role of a strong interaction between the s‐orbital of hydrogen and the d‐orbitals of Fe, when the Fe is substituted in the Mg(001) surface.…”

“…[11][12][13] Considering the immense importance of Fe in catalysis, [14] our interesti nt he presenti nvestigation is to explore the effect of iron-containing additives for MgH 2 .I nt he literature contradictory opinions have been reported regarding the chemical role of Fe, although it is generally agreedt hat Fe can improve the hydrogen de-and absorption performance when added as an additive to MgH 2, [15][16][17] .W hereas most of the experimental studies do not confirm the substitution of Fe in the lattice of MgH 2 ,v arioust heoretical studies suggest that Fe substituted Mg/MgH 2 surfaces actively influence the Mg-H interaction. The DFT calculations by Wu et al [18] suggested the role of as trong interaction between the s-orbitalo fh ydrogen and the d-orbitals of Fe, when the Fe is substituted in the Mg(001) surface. In such ac ase, the performance of the system was shown to be highly dependento nt he diffusion of hydrogen across the Fedoped surface.…”

Modeling reaction pathways for hydrogen evolution and water dissociation on magnesium

“…Although H 2 dissociation on Mg(0001) has been modeled extensively [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37], H 2 desorption from Mg(0001) was only studied by Pozzo and Alfè [19] and Vegge [20]. Moreover, none have modeled the reaction path for water dissociation on Mg(0001) or determined the transition state for HO-H bond breaking.…”

The effect of defects on the hydrogenation in Mg (0001) surface

“…Therefore, we might expect that this implies a considerable diffusion barrier for motion of the chemisorbed H atoms from the surface Pt or other defect sites into the bulk, since this will involve removing H atoms from the Pt or other defect where they are strongly bound into a sublayer where they interact primarily with Mg atoms. Actually, we have displayed this character in another publication [35].…”