Carbon Shell‐Encapsulated Metal Alloy Catalysts with Pt‐Rich Surfaces for Selective Hydrogen Oxidation Reaction

Abstract

The performance of polymer electrolyte membrane fuel cells (PEMFCs) is deteriorated by the occurrence of reverse current flow. To suppress the reverse current flow, a hydrogen oxidation reaction (HOR)‐selective catalyst based on the molecular sieve effect should be developed. Here, considering the carbon solubility in transition metals, carbon shell‐encapsulated metal alloy nanoparticles with superior HOR selectivity were fabricated using carbon source in metal precursors. In particular, we introduced carbon solubility as the important parameter that should be considered in the catalyst design. Using Pt and Co with different carbon solubility, as a model catalyst, the effect of the metal composition of the core material on the carbon shell structure was discussed in detail. Due to the formation of high‐density carbon shell and Pt‐rich surface on the alloy nanoparticle, the HOR selectivity was remarkably enhanced. Therefore, this study provides insights into the development of carbon shell‐encapsulated nanoparticles for reaction‐selective catalysis.

Origin and Formation Mechanism of Carbon Shell-Encapsulated Metal Nanoparticles for Powerful Fuel Cell Durability

“…First, in Figure 3c, Pt acac /C-Ar shows a very small EMSA of 12 m 2 •g −1 , suggesting the formation of a dense carbon shell (Figure S10). As demonstrated in the reference, the dense carbon shell exhibits exceptionally high selectivity for H 2 over O 2 , resulting in a low oxygen reduction reaction (ORR) but an excellent hydrogen oxidation reaction (HOR) [24,26]. Conversely, when H 2 gas is used, a significant increase in the EMSA is observed, indicating that H 2 gas etches the bonding of carbons, leading to a substantial increase in Pt active sites.…”

“…Well-controlled carbon shells are the key to inhibiting structural deformation while maintaining both activity and durability. Thus, the precursor ligand-induced method holds a distinct advantage in this regard [21][22][23][24][25][26][27]. Despite this, the origin and formation mechanism of carbon shell formation through these precursor-based methods have not been clearly elucidated yet.…”

Redesign of Anode Catalyst for Sustainable Survival of Fuel Cells

“…This absorption enabled the formation of MCL on the surface of Pt nanoparticles through carbonization during the subsequent heat treatment (refer to Figure 1A). [37][38][39][40][41][42][43] As observed from the transmission electron microscopy (TEM) image depicted in Figure 1B,C well-dispersed Pt nanoparticles (average size: ≈3 nm, Figure 1C) were formed on the carbon support (Figure S1, Supporting Information). Moreover, the high-resolution (HR)-TEM image conclusively confirmed the presence of the ultrathin MCL formed on the Pt surface (inset in Figure 1B).…”

MnO–Co@Pt nanowires encapsulated in N-doped porous carbon derived from MOFs for efficient electrocatalytic methanol oxidation reaction

“…Based on the synergistic effect between CoFe and Pt the catalyst mass activity of MOR reached 914.80 mA mg Pt −1 , which is 3.3 times higher than that of commercial Pt/C. Ko et al 18 successfully prepared a controllable carbon shell-encapsulated Pt 1 Co 2 @C/C alloy catalyst. The reliability and stability of the carbon shell, acting as a molecular sieve layer, were convincingly demonstrated.…”