Surface Composition and Lattice Ordering-Controlled Activity and Durability of CuPt Electrocatalysts for Oxygen Reduction Reaction

Abstract

We report the enhanced activity and stability of CuPt bimetallic tubular electrocatalysts through potential cycling in acidic electrolyte. A series of CuPt tubular electrocatalysts with sequential increased lattice ordering and surface atomic fraction of Pt were designed and synthesized by thermal annealing to reveal their improved electrocatalytic properties. These low-Pt-content electrocatalysts with Pt shell are formed through the thermal annealing and following potential cycling treatment. The catalysts (C1) with a low atomic fraction of Pt on the surface and low lattice ordering in the bulk are treated in acidic electrolyte, resulting in the formation of a Pt shell with relatively low activity and stability. However, the catalysts (C2) with a Pt-rich surface and high lattice ordering have a highly enhanced electrochemical surface area after potential cycling via surface roughing. The rough Pt shell of the C2 catalysts is achieved by leaching of surface Cu and the concomitant morphology restructuring. The C2 Pt surface demonstrated highly improved specific and mass activities of 0.8 mA cm Pt −2 and 0.232 A mg Pt −1 at 0.9 V for oxygen reduction reaction (ORR), and after 10 000 cycles, the C2 catalysts display almost no loss of the initial electrochemical active surface area (ECSA). Meanwhile, the stability of these CuPt catalysts shows regular change. Moreover, after a long-term stability measurement, the ECSA of C2 catalysts can be restored to the initial value after another potential cycling treatment, and thus, this kind of electrocatalyst may be developed as next-generation restorable cathode fuel cell catalysts.

Carbon-supported PtCo2Ni2 alloy with enhanced activity and stability for oxygen reduction

“…The energy-dispersive X-ray (EDX) line-scan analysis along the cross-section of PtCo 2 Ni 2 (treated at 600°C) further confirms the formation of the Pt-enriched surface structure (Figs 3c and d). The same results were also observed in our previous work that thermal-treated CuPt tubes showed quite weak Cu redox peaks and led to the increase of the Pt atomic fraction i n the surface region [24].…”

“…with altered surface electronic structure would exhibit high catalytic activity for the ORR [21−34]. Recently, our research on Pt-based binary and ternary electrocatalysts revealed that excellent catalytic activity for ORR, fo rmic acid oxidation, and methanol oxidation could be achieved by alloying Pt with other cheaper transition elements such as Pd, Ni, and Cu by taking advantages of the altered electronic structure of Pt and the favorable surface composition of the alloy electrocatalyst [18,21,24,35,36]. For instance, a mixed PtPd alloy surface could be obtained by surface atomic redistribution of ternary PtPdCu upon potential cycling in an acidic electrolyte, and the distinctive topmost layer played a key role in the enhancement of catalytic activity [35].…”

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

“…3. During surface segregation, the degree of order for the catalyst structure is improved, resulting in high catalytic performances [247,248,360]. 4.…”

Recent Advances on Controlled Synthesis and Engineering of Hollow Alloyed Nanotubes for Electrocatalysis

“…In most cases, 1D hollow alloy nanotubes are synthesized via a straightforward templating method due to the existence of multitudinous templates. Either for the hard template method or the chemical templating (self‐templating) method, various catalysts can easily be obtained because of the variety of precursors and starting templates. Encouragingly, many types of alloy solid/smooth nanotubes, porous nanotubes, and hierarchical nanotubes have been successfully prepared via the aforementioned rationally designed strategies …”