Hydrogen
energy has become one of the most attractive candidates
to replace traditional fossil fuels because of its lack of pollution
and its high energy density. Electrocatalytic water splitting is a
“green” and sustainable way to produce hydrogen but
is still not sufficiently efficient at this stage. In recent years,
Ce-based materials have become very popular as the electrocatalysts
for water splitting primarily because of the multivalence state of
Ce and easily formed oxygen vacancies readily formed in CeO2. However, until now, this interesting subject has seldom been reviewed,
especially for electrocatalysts for alkaline water splitting. Herein,
we outline and discuss recent progress on the active sites of Ce-based
electrocatalysts for hydrogen evolution and oxygen evolution. Oxygen
vacancies and interfaces between CeO2 and mixed metal components
could provide optimized binding of hydrogen evolution reaction (HER)
intermediates, thus promoting HER performance. For the oxygen evolution
reaction (OER), Ce3+/Ce4+ redox, oxygen vacancies,
and exogenous transition metals could optimize the binding of OER
intermediates toward top catalytic activities. The aim of this review
is to seek an overall understanding about the reaction sites in Ce-based
electrocatalysts for water splitting, which may provide a guide for
the future development of HER and OER Ce-based electrocatalysts toward
industrial applications.
CeO2 has played an important role in improving
the oxygen
evolution reaction (OER) performance of transition metals-based catalysts
whether as a hybrid, substrate, or interface. The high OER activity
is ascribed to the optimized transition metals and/or the formed oxygen
vacancies. In this work, the interface effect between CoO and CeO2 is reported to be the reason for the excellent OER performance
of CoO/CeO2. Compared with sole CoO or CoO/CeO2-L (larger CoO nanosheets), CoO/CeO2 has exhibited higher
OER performance due to the faster kinetics and higher OER intrinsic
activity because of the large amount of Co/Ce interfaces. Theoretical
calculations reveal the generation of the reconstructed active center
of the Co–O–Ce configuration due to the strong electron
coupling effect between CeO2 and CoO. The Co–O–Ce
hybridization at the interface brings in the unoccupied oxygen states,
acting as the acceptor-like states and optimizing the bonding energy
with OER intermediates. The findings give an avenue to design excellent
CeO2-containing OER catalysts through interface control.
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