Hydrogen adsorption on transition metal carbides: a DFT study

Abstract

This work investigates the hydrogenation of the surfaces of those materials and its relationship with the catalytic behaviour of these materials.

Carbon dioxide and water co-adsorption on the low-index surfaces of TiC, VC, ZrC and NbC: a DFT study

“…45 Other work focused on the hydrogenation of these same carbon-terminated {111} surface also found these termination to be unstable. 81 Furthermore, these results are also in good agreement with experimental observations, which report that the {111} surface of TiC is exclusively terminated by titanium. 60,82 Fig .…”

“…The carbon-terminated {111} surface were all unstable in the presence of water, in a manner that is not only observed in the presence of CO 2 , but also seen on the hydrogenated surfaces, where in the presence of molecular hydrogen only the {111}C surface of NbC was stable. 81 In contrast to the carbon terminated surface, which were only stable in the absence of an adsorbate, the metal terminated {111} surfaces were both stable and strongly adsorbed H 2 O in the hollow site (HS) configuration (see Fig. 7).…”

“…agreement with our work on molecular hydrogen adsorption. 81 It appears that the surface d-bands donate approximately half of this electron density with the other half coming from the hydroxyl group.…”

Insight into anomalous hydrogen adsorption on rare earth metal decorated on 2-dimensional hexagonal boron nitride: a density functional theory study

“…18 Another application of studying hydrogen interaction with transition metals is in catalysis and hydrogen evolution from water. 19 Transition metals are characterized by the presence of many d atomic orbitals for electrons. For early transition metals like Ti, the 18electron rule, generally applicable for predicting the formation of organometallic compounds, has been successfully used to determine the maximum number of hydrogen molecules adsorbed.…”

Assessing the usefulness of transition metal carbides for hydrogenation reactions

“…"# of -0.60 eV. The Kubas mode for adsorbed H 2 , previously described in the literature for a number of the here contemplated TMCs, 14,[25][26][27] corresponds to an almost dissociated H 2 molecular state where both atomic H species are adsorbed on the same C atom, with H 2 bond lengths ranging 1.68 to 1.80 Å, see Table S2 of the ESI, and having a non-negligible interaction between them, estimated to be in between -0.55 to -0.92 eV, see Table S2 of the ESI. The adsorption energies reported on Table 1 show that the formation of the Kubas mode is actually thermodynamically favorable on group IV TMCs and -MoC, with adsorption energies stronger than those of molecular H 2 adsorption on top-C or top-M, yet Kubas H 2 is not thermodynamically favored on group V TMCs.…”