Highly Stable and Efficient Catalyst with In Situ
Exsolved Fe–Ni Alloy Nanospheres Socketed on an Oxygen Deficient
Perovskite for Direct CO<sub>2</sub> Electrolysis
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Abstract
The massive emission
of carbon dioxide (CO<sub>2</sub>), the major
portion of greenhouse gases, has negatively affected our ecosystem.
Developing new technologies to effectively reduce CO<sub>2</sub> emission
or convert CO<sub>2</sub> to useful products has never been more imperative.
In response to this challenge, we herein developed novel in situ exsolved
Fe–Ni alloy nanospheres uniformly socketed on an oxygen-deficient
perovskite [La(Sr)Fe(Ni)] as a highly stable and efficient catalyst
for the effective conversion of CO<sub>2</sub> to carbon monoxide
(CO) in a high-temperature solid oxide electrolysis cell (HT-SOEC).
The symmetry between the reduction and reoxidation cycles of this
catalyst indicates its good redox reversibility. The cathodic reaction
kinetics for CO<sub>2</sub> electrolysis is significantly improved
with a polarization resistance as low as 0.272 Ω cm<sup>2</sup>. In addition, a remarkably enhanced current density of 1.78 A cm<sup>–2</sup>, along with a high Faraday efficiency (∼98.8%),
was achieved at 1.6 V and 850 °C. Moreover, the potentiostatic
stability test of up to 100 h showed that the cell was stable without
any noticeable coking in a CO<sub>2</sub>/CO (70:30) flow at an applied
potential of 0.6 V (vs OCV) and 850 °C. The increased oxygen
vacancies together with the in situ exsolved nanospheres on the perovskite
backbone ensures sufficiently active sites and consequently improves
the electrochemical performance for the efficient CO<sub>2</sub> conversion.
Therefore, this newly developed perovskite can be a promising cathode
material for HT-SOEC. More generally, this study points to a new direction
to develop highly efficient catalysts in the form of the perovskite
oxides with perfectly in situ exsolved metal/bimetal nanospheres