Wavy PtCu alloy nanowire networks with abundant surface defects enhanced oxygen reduction reaction

Bimetallic platinum-copper (Pt-Cu) alloy nanowires have emerged as a novel class of fuel cell electrocatalysts for oxygen reduction reaction (ORR) due to their intrinsic high catalytic activity and durability, but preparing such electrocatalysts with clean surface via facile method is still a challenge. Herein, PtCu alloy with nanowire networks (NWNs) structure is obtained by a simple modified polyol method accompanied with a salt-mediated self-assembly process in a water/ethylene glycol (EG) mixing media. The formation mechanism of PtCu NWNs including the morphological evolution and the relevant experimental parameters has been investigated systematically. We propose that a micro-interface in H₂O-EG media formed with the assistance of disodium dihydrogen pyrophosphate (Na₂H₂P₂O₇) and its unique nature of coordinating with Pt²⁺ or Cu²⁺ play critical roles in the formation of NWNs. When tested as ORR catalyst, the PtCu_NWNs/C exhibits much higher activity and durability than that of Pt_NWNs/C and commercial Pt/C, even exceeding the target of DOE in 2020. The excellent performance of PtCu_NWNs/C could be attributed to the unique structure of NWNs with 2.4 nm ultrathin wavy nanowires and plentiful surface defects and the modified electronic effect caused by alloying with Cu atoms.