Rare earth-decorated platinum-nickel-cobalt knot-like nanowires achieve efficient bifunctional electrocatalysis for PEMFC

Designing workable and high-performance platinum (Pt)-based multicomponent nanomaterials with the help of selective rare earth (RE) elements is necessary yet challenging for bifunctional catalysis in proton exchange membrane fuel cell (PEMFC). Herein, a class of trimetallic Pt-nickel-cobalt knot-like nanowires decorated with single sites and clusters of scandium (Sc-PtNiCo KNWs) can be synchronously applied as the oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) catalysts for PEMFC. Notably, the Sc-PtNiCo KNWs/C demonstrates the 9.0/6.8 times higher mass/specific activities than those of commercial Pt/C for ORR and limited current decay of 5.0 %/13.6 % after chronoamperometry tests in 100 ppm CO-H₂/pure H₂ media for HOR. More importantly, the membrane electrode assembly (MEA) with Sc-PtNiCo KNWs/C as cathodic and anodic catalysts can simultaneously reach the high peak power density of 1963.1 mW cm⁻² and mass activity of 0.88 A mg_Pt⁻¹@0.9 V_IR-free in H₂-O₂ medium, along with the much improved stability and CO-tolerance property, revealing a large potential in practical fuel cell device. Experimental analyses and theoretical calculations further evidence that the selective introduction of Sc optimizes the binding strength of intermediate via weakening the electron transfer of interface, contributing to its much enhanced performances.