Ceria
substituted with zirconium (Ce1–x
Zr
x
O2) is a promising
material in two-step thermochemical CO2/H2O
splitting cycles due to its great oxygen storage capacity and potential
fuel production. However, the Ce1–x
Zr
x
O2 solid solution exhibits
a relatively slower fuel release rate than cerium oxide alone. Herein,
in order to improve the solar-to-fuel energy conversion efficiency,
noble metal catalysts (RuO
x
, PtO
x
, and IrO
x
) are used
to boost the CO release rate of Ce0.85Zr0.15O2 (CZ15)-based two-step thermochemical CO2 splitting. Compared with intrinsic Ce0.85Zr0.15O2, the maximal CO release rate can be increased by 35%
after loading 0.4 atom % IrO
x
as a catalyst
on the surface of Ce0.85Zr0.15O2.
Interestingly, the initial CO release rate can be increased by three
times when a small amount of IrO
x
(1.0
atom %) is doped into the crystal structure of Ce0.85Zr0.15O2 through a solution combustion method. This
catalytic effect is ascribed to the increased mixed ionic and electric
conductivity within the ceramic bulk and the enhanced chemical reaction
rate at the gas–solid interface for iridium-decorated ceria-zirconia
solid solution. Our work demonstrates that interface engineering and
bulk modification through adding the selected catalyst can effectively
enhance the CO2 splitting rate of Ce1–x
Zr
x
O2 oxygen
carriers, which provides a promising strategy to promote the fuel
release rates of other kinetics-restricted thermochemical CO2/H2O splitting cycles.