Low‐temperature fuel cells (LTFCs) are considered to be one of the most promising power sources for widespread application in sustainable and renewable energy conversion technologies. Although remarkable advances have been made in the mass activity of catalysts, mass transport impedance needs to be urgently addressed at a well‐designed membrane electrode assembly (MEA) scale. Increasing the loading of electrocatalysts is conducive to prepare thinner and more efficient MEAs owing to the resulting enhanced reactant permeability, better proton diffusion, and lower electrical resistance. Herein, recent progress in high‐loading (≥40 wt.%) Pt nanoparticle catalysts (NPCs) and high‐loading (≥2 wt.%) single‐atom catalysts (SACs) for LTFC applications are reviewed. A summary of various synthetic approaches and support materials for high‐loading Pt NPCs and SACs is systematically presented. The influences of high surface area and appropriate surface functionalization for Pt NPCs, as well as coordination environment, spatial confinement effect, and strong metal‐support interactions (SMSI) for SACs are highlighted. Additionally, this review presents some ideas regarding challenges and future opportunities of high‐loading catalysts in the application of LTFCs.
Carbon
supports for cathodic catalysts in proton-exchange membrane
fuel cells suffer from rapid corrosion and instability; therefore,
alternative supports with a stable structure and a high electric conductivity
are highly required. In this paper, a three-dimensional support hybridized
by MXene and Ketjen Black is developed, in which Ketjen Black is sandwiched
between MXene nanosheets (MCM). After decorating with Pt nanoparticles
by a facile wet-chemical approach, a three-dimensional (3D) Pt/MCM
catalyst is obtained. The intercalated Ketjen Black prevents the stacking
of MXene nanosheets, thus increasing the specific surface area of
the catalyst and exposing the active sites. The strong interaction
between functionalized MXene nanosheets and Pt nanoparticles further
enhances its intrinsic electrocatalytic activity. Pt/MCM demonstrated
encouraging ORR activity with the half-wave potential and specific
activity of 0.892 V and 0.377 mA·cm–2, respectively,
surpassing the state-of-the-art Pt/C catalysts. Especially, Pt/MCM
achieves ultrahigh durability with a 1 mV decrease in half-wave potential
and a 1.73% decrease in mass activity after an accelerated durability
test. Given the performance and structure–activity relationships
of Pt/MCM, it holds great potential for various energy and catalysis-related
applications.
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