Highly Durable and Active PtFe Nanocatalyst for Electrochemical Oxygen Reduction Reaction

Abstract

Demand on the practical synthetic approach to the high performance electrocatalyst is rapidly increasing for fuel cell commercialization. Here we present a synthesis of highly durable and active intermetallic ordered face-centered tetragonal (fct)-PtFe nanoparticles (NPs) coated with a "dual purpose" N-doped carbon shell. Ordered fct-PtFe NPs with the size of only a few nanometers are obtained by thermal annealing of polydopamine-coated PtFe NPs, and the N-doped carbon shell that is in situ formed from dopamine coating could effectively prevent the coalescence of NPs. This carbon shell also protects the NPs from detachment and agglomeration as well as dissolution throughout the harsh fuel cell operating conditions. By controlling the thickness of the shell below 1 nm, we achieved excellent protection of the NPs as well as high catalytic activity, as the thin carbon shell is highly permeable for the reactant molecules. Our ordered fct-PtFe/C nanocatalyst coated with an N-doped carbon shell shows 11.4 times-higher mass activity and 10.5 times-higher specific activity than commercial Pt/C catalyst. Moreover, we accomplished the long-term stability in membrane electrode assembly (MEA) for 100 h without significant activity loss. From in situ XANES, EDS, and first-principles calculations, we confirmed that an ordered fct-PtFe structure is critical for the long-term stability of our nanocatalyst. This strategy utilizing an N-doped carbon shell for obtaining a small ordered-fct PtFe nanocatalyst as well as protecting the catalyst during fuel cell cycling is expected to open a new simple and effective route for the commercialization of fuel cells.

Confined catalysis under two-dimensional materials

“…Recent reports confirm that CO oxidation, methanation, and ORR reactions happen on the metal nanocatalysts covered with Gr or h-BN shells (55)(56)(57)(58). Particularly, enhanced ORR activity has been observed on Pt nanocatalysts with Gr shells (57)(58)(59), which is consistent with our theory prediction illustrated in Fig. 5.…”

Layer‐by‐Layer Motif Architectures: Programmed Electrochemical Syntheses of Multilayer Mesoporous Metallic Films with Uniformly Sized Pores

“…[13] Direct-alcohol fuel cells (DAFCs) have been considered as attractive energyconversion devices.Inthis study,methanol and ethanol were selected as model molecules for studying the electrocatalytic performance of the mesoporous films.F irstly,t he electrochemically active surface areas (ECSA) of multilayer m-Pd/ PdPt, m-PdPt, m-Pd and m-Pt films,a sw ell as commercially available Pd black and Pt black, were examined from the COstripping measurement by assuming ac harge density of 420 mCcm À2 for the electro-oxidation of aCOm onolayer on aP t/Pd surface. [15] TheC Os tripping voltammograms of the m-Pt, m-PdPt, multilayer m-Pd/PdPt, and m-Pd films (Figure 4a)c learly show that the onset and peak potential of the adsorbed CO oxidation are positively shifted as the content of Pd in the films is increased. [15] TheC Os tripping voltammograms of the m-Pt, m-PdPt, multilayer m-Pd/PdPt, and m-Pd films (Figure 4a)c learly show that the onset and peak potential of the adsorbed CO oxidation are positively shifted as the content of Pd in the films is increased.…”

Rational Design and Synthesis of Low-Temperature Fuel Cell Electrocatalysts

“…And although surface Au atoms were thought to block Pt sites and decrease activity [94], Kodama et al [99] demonstrated that both activity and stability can be enhanced by depositing Au atoms selectively on (100) step sites. Furthermore, ordered Pt-based intermetallic alloys also exhibit better stability than corresponding random alloys [81,84] with carbon-supported ordered intermetallic Pt 3 Co nanoparticles being a representative example [81]. Lastly, compared to nanoparticles, one-dimensional (1D) analogues (CoPt nanowires, Pt nanotubes [92]), 2D structures (PtPb nanoplates), and 3D array networks [68] (nanostructured thin film catalysts produced by 3 M) possess fewer lattice boundaries and defect sites on their surfaces and are therefore less vulnerable to dissolution and Ostwald ripening.…”