posted on 2020-04-29, 20:11authored byNicholas
C. Nelson, János Szanyi
Identifying the role
of oxide supports in transition-metal catalysis
is critical toward our understanding of heterogeneous catalysis. The
water–gas shift (WGS) reaction is a prototypical example where
the oxide support dictates catalytic activity, yet the cause for this
remains uncertain. Herein, we show that a single descriptorthe
equilibrium constant for hydroxyl formationrelates the WGS
turnover frequency across disparate oxide supports. The dissimilar
equilibrium constant, or oxophilicity, between early and late transition
metals exemplifies the utility of metal–support interfacial
sites to circumvent adsorption-energy scaling restrictions, thereby
providing bifunctional gains for the WGS reaction class. In relation,
the equilibrium constant for hydroxyl formation is equivalent to the
equilibrium constant for the formal heterolytic dissociation of hydrogen
and therefore reflects the ability of the metal–support interface
to participate in hydrogen heterolysis. The ubiquitous coexistence,
yet divergent chemical reactivity of homo- and heterolytically activated
hydrogen, renders the identity of the oxide support central toward
our understanding of hydrogenation catalysis.