Understanding the Grain Boundary Behavior of Bimetallic Platinum–Cobalt Alloy Nanowires toward Oxygen Electro-Reduction

Abstract

Grain boundaries (GBs) are defects in crystal structures, which are in general known to be highly active toward various electrocatalytic reactions. Herein, we identify the adverse behaviors of the GBs for bimetallic platinum–cobalt (Pt–Co) nanocatalysts in the oxygen reduction reaction (ORR). As model catalysts, GB-rich Pt–Co nanowires (Pt–Co GB-NWs) and single-crystalline Pt–Co nanowires (Pt–Co SC-NWs) are synthesized. They have very similar diameters, Pt-to-Co ratios, and Pt-rich surface structures, except for the GB populations, which can be precisely controlled by applying an external magnetic field during their synthesis. The presence of GBs in Pt–Co NWs promotes Co leaching at an applied electrochemical potential, inducing significant changes in the surface Pt-to-Co ratio. The resulting Pt–Co GB-NWs perform only half the ORR activity compared with the Pt–Co SC-NWs. As a result, it is revealed that the surface GB sites are deactivated by causing elemental leaching and may not act as an ORR promoter for the Pt–Co nanowire catalyst.

Modulating the intrinsic properties of platinum–cobalt nanowires for enhanced electrocatalysis of the oxygen reduction reaction

“…3D exhibits that the Pt 70 Co 30 /C nanoalloy catalyst has the highest MA (2.3 A mg Pt −1 ) and excellent SA (4.19 mA cm −2 ), which are 4.0 and 3.6 times higher than that of Pt/C NWs. The electrocatalytic performance of the Pt n Co 100− n /C nanoalloy catalysts are compared with that of PtCo alloy catalysts previously reported (Table S2, ESI†), 47–51 and indicate that the Pt n Co 100− n /C nanoalloy catalysts possess a competitive property without post-synthesis treatment. Therefore, we focus on the Pt 70 Co 30 /C nanoalloy catalyst to characterize the stability of the NWs.…”

“…and excellent SA (4.19 mA cm À2 ), which are 4.0 and 3.6 times higher than that of Pt/C NWs. The electrocatalytic performance of the Pt n Co 100Àn /C nanoalloy catalysts are compared with that of PtCo alloy catalysts previously reported (Table S2, ESI †), [47][48][49][50][51] durability is provided by characterizing the morphology and composition. The morphology of the Pt 70 Co 30 /C catalyst still retains NWs after 10 000 cycles (Fig.…”

Excess dopant effect in platinum‐based alloys toward the oxygen electroreduction reaction

“…Hydrogen (H 2 ) has been considered one of the promising clean energy sources that generate electricity with high energy density 1–6 . Proton exchange membrane fuel cells (PEMFCs), which utilize H 2 as fuel to produce electricity, release water as a product, eliminating a significant carbon footprint 7–9 . The most difficult task to optimize the performance of PEMFCs relates to the sluggish cathodic oxygen reduction reaction (ORR) 10–12 .…”

High‐Density Frustrated Lewis Pair for High‐Performance Hydrogen Evolution

“…These high‐density and adjacent metal pairs can provide sufficient reactive sites and greatly shorten the transport distance of active intermediates in a multistep reaction. [ 6 ] However, electron transfer due to electronegativity differences is weak and uncontrollable, [ 7 ] which is insufficient to support the needs of most catalytic reactions.…”