Abstracts Book - IMRC 2018

• SC3-O018 Invited Talk
CATALYTIC PROPERTIES OF COBALT AND MODIFIED COBALT
(OXY)HYDROXIDES FOR THE OXYGEN EVOLUTION REACTION:
EFFECTS OF COMPOSITION, LOCAL STRUCTURE AND IN-SITU
STRUCTURAL EVOLUTION
Bruce Koel 1
1
Princeton University, Chemical and Biological Engineering, United States.
The development of improved catalysts for the oxygen evolution reaction (OER)
is important for solar hydrogen production and a number of other emergent
technologies in energy conversion and storage. An understanding of reaction
mechanisms andcorrelations with catalyst properties provides rational design
principles to accelerate catalyst development. The effects of doping and catalyst
processing on the catalytic properties of cobalt (oxy)hydroxides (CoOOH) will be
used to illustrate structure-activity correlations. Catalyst performance of CoOOH
and M-modified CoOOH (M=Ni, Mn) correlated with increasing concentration of
dispersed Ni ions, but not Mn. Ni incorporation reduces charge transfer
resistances and improve catalyst ability to stabilize surface intermediates, but
Mn incorporation impedes intermediate stabilization. Using ambient pressure
photoelectron spectroscopy, we have directly observed better stability of
surface hydroxyl groups as a result of Ni incorporation. Additionally, extensive
surface hydroxylation observed under mild conditions (27 °C, 1 torr H2O)
indicated a low barrier to phase transformation. This prompted our
investigation of catalyst structural evolution during OER using operandoRaman
spectroscopy. This identified the active structure of related NiCoOxHycatalysts
as NiOOH-h-CoO2, which can be formed by an irreversible transformation of
spinel Co3O4toamorphous CoO followed by a reversible conversion of the
catalyst to NiOOH-h-CoO2.
Keywords: operando, catalyst, cobalt
Presenting authors email: bkoel@princeton.edu