  Metal/oxide support perimeter sites are known to provide unique properties
because the nearby metal changes the local environment on the support surface.
In particular, the electron scavenger effect reduces the energy necessary for
surface anion desorption, thereby contributes to activation of the (reverse)
Mars-van Krevelen mechanism. This study investigated the possibility of such
activation in hydrides, carbides, nitrides, and sulfides. The work functions
(WFs) of known hydrides, carbides, nitrides, oxides, and sulfides with group 3,
4, or 5 cations (Sc, Y, La, Ti, Zr, Hf, V, Nb, and Ta) were calculated. The WFs
of most hydrides, carbides, and nitrides are smaller than the WF of Ag,
implying that the electron scavenger effect may occur when late transition
metal nanoparticles are adsorbed on the surface. The WF of oxides and sulfides
decrease when reduced. The surface anion vacancy formation energy correlates
well with the bulk formation energy in carbides and nitrides, while almost no
correlation is found in hydrides because of the small range of surface hydrogen
vacancy formation energy values. The electron scavenger effect is explicitly
observed in nanorods adsorbed on TiH2 and Ti2O3; the surface vacancy formation
energy decreases at anion sites near the nanorod, and charge transfer to the
nanorod happens when an anion is removed at such sites. Activation of hydrides,
carbides, and nitrides by nanorod adsorption and screening support materials
through WF calculation are expected to open up a new category of supported
catalysts.
