Fabricating high-loading ultra-small PtCu3/rGO via a traceless protectant and spray-freeze-drying method

Abstract

Exploring excellent catalysts for oxygen reduction reaction (ORR) with a facile and cost-effective method is desirable but remains challenging. Herein, ultra-small PtCu3 nanoparticles (ca. 2.7 nm), immobilized on reduced graphene oxide (rGO), were synthesized via a novel and general strategy. Traceless protectant, NH4OH, was used to resist the aggregation of graphene oxide (GO), and the spray-freeze-drying method ensures excellent dispersion of the Pt and Cu precursors, which could not be achieved by other reported drying methods. After annealing, the nanoparticles with the highest mass loading, 52%, among reported ordered Pt-based catalysts were obtained. The PtCu3/rGO shows a remarkable electrocatalytic performance. Density functional theory calculations elucidate that PtCu3 possess a lowered energy barrier of the rate-determining step, contributing to significantly improved ORR kinetics. This strategy was extended to the synthesis of other binary- and quaternary-metallic Pt-based nanoparticles, which proved its generality and applicability towards the potential commercialization of fuel cell technologies.