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

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Figure 3. Mechanism of carbon formation on Ni and Ce surfaces. Reproduced with permission from Ref. . Copyright 2018, Springer
Nature.

In addition to Ni and Cu, other metal-doped cermets can be used as SOEC cathodes. Ag has high electronic
conductivity and chemical stability . Compared to precious metals, Fe is cheaper, but it is easily oxidized at
[14]
high temperatures. The alloy represents a significant avenue for enhancing the performance of electrode
materials. The prevailing approach entails the uniform attachment of nano-alloy particles to the oxide
surface, achieved through the in situ exsolution or impregnation techniques . In a recent study,
[15]
Wang et al. prepared Ni-M (M=Fe, Pt, Co, Cu, Ru) cathodes, respectively, and observed that the addition of
Pt and Co resulted in a decrease in current density, whereas the addition of Fe, Cu, and Ru led to an
improvement in electrode performance . Among the alloys, the Ni-Fe alloy exhibited the most favorable
[16]
performance. The main reason for this result is that Fe can effectively inhibit the agglomeration of Ni
particles and the coking, thereby enhancing the stability of materials. Accordingly, the current research will
focus on determining the optimal ratio of doping elements to enhance the promotion of dopants on
electrode performance.

In conclusion, the implementation of diverse metal or alloy doping materials can enhance the
electrochemical performance and catalytic activity of cathodes. However, the performance of other cermets
is still difficult to compare with that of Ni-based materials, and future research is needed to address the
issues of stability and degradation in long-term operation. Table 2 presents a comparative analysis of the
electrochemical performance of various cermets. Among them, the performance of Ni-based materials is
significantly superior to that of other metal element doping.

Perovskite oxide-based materials
Compared to traditional cermet electrodes, perovskite oxides exhibit superior mixed ionic-electronic
conductivity (MIEC), resistance to carbon deposition, and high-temperature stability . Figure 4 depicts the
[23]
structural configurations of single perovskites (ABO ) and double perovskites (A′AB′BO ).
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The MIEC of perovskites enables the reaction to occur not only at the TPBs, but also at the gas-solid
interface. This effectively reduces the polarization resistance. However, the lower catalytic activity of
perovskite oxides greatly limits their applications. The A, B, and O sites in the perovskite structure can
introduce various ions . The use of doping, impregnation to introduce nano-catalysts, and in-situ
[24]
exsolution can facilitate the formation of lattice defect structures and increase the concentration of oxygen