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Chen et al. Energy Mater. 2025, 5, 500045 https://dx.doi.org/10.20517/energymater.2024.144 Page 7 of 27

[33]
conditions . Nevertheless, the poor catalytic performance and harsh synthesis conditions restrict their
further application. The impregnation of Ni or Fe nanoparticles onto the LSV surface can significantly
[34]
improve its current density, and the ohmic resistance is almost unchanged, which is a promising method .

SrTiO (STO)-based perovskites represent a class of materials that have been the subject of considerable
3-δ
research interest. The most widely used composition is 20% La-doped La Sr TiO (LST) at the A-site. In
0.2
3-δ
0.8
air, LST exhibits p-type conductivity, whereas in reducing atmospheres, it exhibits n-type conductivity .
[35]
LST demonstrates excellent stability under high-temperature reducing conditions and resistance to carbon
accumulation, making it suitable for CO electrolysis. However, its relatively low catalytic activity and
2
oxygen ionic conductivity present obstacles to its broader application. Loading with nanometallic particles
is an effective way to improve the catalytic performance .
[36]
In addition to LST, Nb-doped STO (STN) materials are also widely used. The catalytic activity and cycling
stability of STN can be enhanced through the doping of Nb elements at the B-site. Nevertheless, its direct
application in steam electrolysis will encounter the challenge of inadequate catalytic efficacy. Yang et al.
prepared (Sr ) (Ti Nb ) Ni O (STNNO) cathodes with A-site defects and B-site excess by loading Ni
3
0.94 0.9
0.1
0.1 0.9
0.9
nanoparticles on the STN surface . It was demonstrated that the exsolution of Ni particles on the STN
[37]
surface during the redox process was entirely reversible.
Double perovskites
The crystal structure of double perovskites comprises two mutually stacked metal hexahedral layers, where
the metal elements are in disparate oxidation states. This configuration can offer active sites for electrolysis,
and enhance the electrical conductivity. The presence of metal ions in two oxidation states within the
structure results in a more complex oxygen ion conduction channel, thereby enabling precise regulation of
[8]
the oxygen ion conduction properties .

Sr Fe Mo O (SFM) is a kind of prevalent double perovskite, which is an optimal SOEC cathode material
2
1.5
0.5
6-δ
due to its remarkable stability under redox conditions, favorable coefficient of thermal expansion, and high
MIEC . The performance of SFM can be enhanced by optimizing the ratio of Fe/Mo . The oxidation
[38]
[39]
ability increases with Fe content, which further enhances the hybridization of metal and oxygen, bringing
the O 2p energy band closer to the Fermi energy level, thus increasing the concentration of oxygen
vacancies and improving the catalytic activity of the material. Moreover, doping with elements such as
Nb , Zr , Ba , and others is also worth studying.
[41]
[42]
[40]
In addition to A and B-site doping, anionic doping of oxygen vacancies is also a viable approach. F-doping
improves the adsorption capacity of CO and the volumetric oxygen vacancy concentration, reduces
2
polarization resistance, and accelerates the chemical reaction rate and the surface diffusion rate. The
perovskite oxyfluoride compound, Sr Fe Mo O F (F-SFM), has a lower polarization resistance than that
6-δ 0.1
2
1.5
0.5
of SFM .
[43]
The Mn-O-Mn lattice, formed by Mn ions of different valence states in PrBaMn O (PBM)-based
2
5+δ
perovskites, facilitates the transport of oxygen ions and electrons, exhibits excellent carbon resistant
properties, and demonstrates considerable potential as an electrolytic CO cathode material . The doping
[44]
2
of PrBaFe O (PBF) with Co has been demonstrated to enhance the electrochemical performance.
2
5+δ
PrBaFe Co O (PBFC02) is susceptible to decomposition during the reaction. However, it can be
1.8
5+δ
0.2
restored to its original structure through air calcination. Additionally, its favorable redox properties were
highlighted. The electrochemical performance of PBFC02 was evaluated, and it was determined that the