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Page 24 of 31 Chen et al. Microstructures 2023;3:2023025 https://dx.doi.org/10.20517/microstructures.2023.12

catalytic activity and stability with regards to improving the electron conduction, suppressing the
chemisorption of small molecules, and increasing the interaction between metal and support. However, a
series of significant challenges remain for the application of TM-supported Pt-based catalysts in PEMFCs.

Firstly, metal-oxide systems and metal-carbide systems suffer from several drawbacks, such as low
electronic conductivity and limited surface area, which can be efficiently optimized by doping strategies
(introducing V ) and coupling superior conductive materials. The SMSI effect between metal and supports
o
can also further be enhanced by doping strategies to change the electronic structure of the support. Metal-
nitride systems can effectively avoid these drawbacks due to their high conductivity, while the specific areas
of TMNs are generally extremely low due to the fact that the high-temperature annealing process is always
needed to synthesize TMNs. In addition, the specific preparation method of the catalysts and the size of the
metal NPs can significantly affect the charge transfer between the metal and the support, while the charge
transfer between the support and the noble metal particle sizes has rarely been reported. Furthermore, the
study of the surface/interface structure and dynamic evolution of TM-supported Pt catalysts in the reaction
environment at the atomic scale is important for the rational design of catalysts and revealing the reaction
mechanism, whereas the key issues such as the interfacial structure performance relationship in the TM-
supported Pt catalytic reaction have not been fully elucidated. Finally, although some typical catalysts with
SMSI show considerable activity and durability for ORR in the rotating ring disk electrode level, while few
electrocatalysts have not yet been practically promoted and applied to the membrane electrode assembly,
thus the practical potential of these catalysts cannot be verified. All in all, although many challenges are still
in the way, the SMSI provides great potential to improve the performance of the catalysts for ORR and
beyond, shedding light on the practical application of these novel materials with high activity and durability.

DECLARATION
Authors’ contributions
Conceived and designed the manuscript: Chen M, Miao Z, Tian X
Drafted and revised the manuscript: Chen M, Rao P, Miao Z, Luo J, Li J, Deng P, Huang W, Tian X

Availability of data and materials
Not applicable.

Financial support and sponsorship
This study was supported by the Hainan Provincial Natural Science Foundation of China (522QN281,
521RC495), the National Natural Science Foundation of China (22109034, 22109035, 52164028, 62105083),
the Foundation of State Key Laboratory of Marine Resource Utilization in South China Sea (Hainan
University, Grant No. MRUKF2021029), the Start-up Research Foundation of Hainan University
(KYQD(ZR)-20008, 21170), and the specific research fund of The Innovation Platform for Academicians of
Hainan Province.

Conflicts of interest
All authors declared that there are no conflicts of interest.

Ethical approval
Not applicable.

Consent to participate
Not applicable.