Lowering metal loadings onto Pt-Pd-Cu/graphene nanoribbon nanocomposites affects electrode collection efficiency and oxygen reduction reaction performance

摘要

PtCu or PtPdCu electrocatalysts have been applied to the oxygen reduction reaction (ORR) to avoid the use of large amounts of Pt, while retaining high catalytic performance and long-term stability. The novel aspect of the present study lies in the employment of lower metal loadings onto Pt-x-Pd-y-Cu-z/GNR nanocomposites (NCs) containing porous dendritic alloy structures, while keeping NC loading onto the glassy carbon (GC) surface at 152.7 mg cm(-2), and obtaining a NC2 (20 mu g(PGM) cm(-2), PGM = platinum group metal) catalyst sufficiently electroactive and stable toward the ORR, with relatively low turbulence in electrolyte flux and affecting to a low degree the hydrodynamics/geometry of a rotating ring-disk electrode (RRDE) and its collection efficiency (N). A model considering the deconvolution of disk currents into currents operating during H2O2 production and those operating during H2O2 electroreduction proved capable of describing thicker, rougher catalyst layers via Tafel analysis. The use of low amounts of metal nanodendrite alloy (11 mgPGM cm(-2), including the metal alloy composition) in the NCs (NC1) enhanced H2O2 production. The high metal alloy nanodendrite loadings (surface roughness, higher ECSA values) for NC4 and NC5 cause the hydrodynamic behavior to deviate from that of a model film. (c) 2019 Elsevier Ltd. All rights reserved.