Design of ternary Pt–CoZn alloy catalysts coated with N-doped carbon towards acidic oxygen reduction

Abstract

Improving the activity and durability of Pt-based electrocatalysts used in the acidic oxygen reduction reaction (ORR) is a great task for the commercial application of proton-exchange membrane fuel cells. Alloying with transition metal elements is one of the most promising strategies, but it is still accompanied by poor catalyst durability due to the leaching of transition metal components. Herein, we report a facile pyrolysis approach for fabricating N-doped carbon-coated Pt-based ternary alloy nanoparticles (Pt–CoZn@NC) by using Co/Zn-based bimetallic zeolitic imidazolate framework-encapsulated Pt nanoparticles (Pt@CoZn-ZIF) as precursors. After optimizing the experimental conditions, the Pt–CoZn@NC-800-10% catalyst exhibited outstanding activity (E_1/2: 0.917 V vs. RHE) and stability (E_1/2 after 5000 cycles: 1 mV), which are superior to those of binary Pt-based alloy catalysts (i.e., Pt–Co@NC and Pt–Zn@NC) and commercial Pt/C catalysts in the acidic ORR. Such enhanced performances are attributed to the favourable ternary alloy structure, which promoted electronic interactions among metal species (Pt, Co, and Zn). A ZIF-derived NC matrix helps to improve the conductivity and catalytic durability due to an increased number of active sites. This work provides a feasible strategy for preparing efficient and stable Pt-based ternary alloy ORR electrocatalysts.