Chemically Ordered Pt–Co–Cu/C as Excellent Electrochemical Catalyst for Oxygen Reduction Reaction

Abstract

This paper reveals the ordered structure and composition effect to electrochemical catalytic activity towards oxygen reduction reaction (ORR) of ternary metallic Pt-Co-Cu/C catalysts. Bimetallic Pt-Co alloy nanoparticles (NPs) represent an emerging class of electrocatalysts for ORR, but practical applications, e.g. in fuel cells, have been hindered by low catalytic performances owning to crystal phase and atomic composition. Cu is introduced into Pt-Co/C lattices to form PtCoxCu1−x/C (x=0.25, 0.5 and 0.75) ternary-face-centered tetragonal (fct) ordered ternary metallic NPs. The chemically ordered Pt-Co-Cu/C catalysts exhibit excellent performance of 1.31 A mg-1 Pt in mass activity and 0.59 A cm-2 Pt in specific activity which are significantly higher than Pt-Co/C and commercial Johnson Matthey (JM) Pt/C catalysts, because of the ordered crystal phase and composition control modified the Pt-Pt atoms distance and the surface electronic properties. The presence of Cu improves the surface electronic structure, as well as enhances the stability of catalysts.

Design principles for the synthesis of platinum–cobalt intermetallic nanoparticles for electrocatalytic applications

“…The incorporation of Cu into the L1 0 -PtCo intermetallic was also reported to form a half-intermetallic PtCo x Cu 1− x ( x = 0.25, 0.5, 0.75). 81 A rationale for making a half-intermetallic is to tune the Pt–Pt distance to improve its catalytic activity.…”

Pt-Based Intermetallic Nanocrystals in Cathode Catalysts for Proton Exchange Membrane Fuel Cells: From Precise Synthesis to Oxygen Reduction Reaction Strategy

“…This further experimentally demonstrates that the L1 0 Pt-Co-Ni system has a high intrinsic ORR activity. In addition, ternary intermetallic compounds such as PtCuCo, PtFeNi, and PtCuNi have also been experimentally demonstrated to have excellent ORR performance, but the mechanisms of activity enhancement still need to be further explored [155][156][157][158].…”

Pt–Fe–Cu Ordered Intermetallics Encapsulated with N-Doped Carbon as High-Performance Catalysts for Oxygen Reduction Reaction

“…Alloying Pt with 3d transition metals (where M is Co, Fe, Cu, etc.) has been recognized as a feasible strategy to simultaneously reduce the Pt loading and promote the activity and durability through unique geometric and electronic configurations. − The existent ligand effect and strain effect incur the position variation of the metal d-band center relative to the Fermi level from the perspectives of short-range charge transfer and long-range geometric effects. , Compared with disordered Pt-based alloys, Pt intermetallic compounds with ordered anisotropy and strong Pt–M bonding are advantageous in further vanquishing transition metal dissolution, agglomeration, and detachment issues during electrocatalysis through a strong 3d–5d orbital coupling effect. − Thus far, binary Pt–M intermetallics, such as tetragonally L1 0 -ordered PtCo and PtFe, cubically L1 2 -ordered Pt 3 Co, and rhombohedral L1 1 -ordered PtCu, have been extensively investigated in the past decades. More recently, structurally ordered intermetallic catalysts based on ternary Pt–M–M′ (M and M′ represent two different transition metals) systems have also been proposed to further optimize the strain, ligand environment, and electronic state through the multielemental coupling, which is expected to yield better activity and durability than binary systems. − Despite being promising, the achievable activity/durability of reported ternary Pt–M–M′ catalysts is still far behind the ideal, largely because of the inevitable dissolution of transition metals, particularly when they are atomically exposed to an acidic environment.…”