ZrO2 anchored core-shell Pt-Co alloy particles through direct pyrolysis of mixed Pt-Co-Zr salts for improving activity and durability in proton exchange membrane fuel cells

Highly active and durable Pt-based catalysts for oxygen reduction reaction (ORR) are very important and necessary for the proton exchange membrane fuel cells (PEMFCs). In this paper, we report the preparation and performance study of ORR catalysts composed of core-shell Pt-Co alloy nanoparticles (NPs) on multi-walled carbon nanotubes (MWCNTs) anchored with ZrO2 NPs (denoted as Pt-Co-ZrO2/MWCNTs). Thanks to the unique three-phase structure, the mass activity of Pt-Co-ZrO2/MWCNTs for ORR at 0.9 V versus reversible hydrogen electrode (RHE) is 1577 mA mg(Pt)(-1), which is similar to 6.6-fold higher than that of the commercial Pt/C (238 mA mg(Pt)(-1)). After 50,000 cycles for durability test, the mass activity of Pt-Co-ZrO2/MWCNTs for ORR remained 88% of its initial value. In stark contrast, that of Pt/C kept only about 56.3% of its initial value. More importantly, its catalytic performance was fully observed/verified in a H-2-air PEMFC single cell test. When the Pt loading of Pt-Co -ZrO2/MWCNTs loaded cathode was one fourth of that with commercial Pt/C as the cathode catalyst, comparable cell performance was achieved. More impressively, the MEA with Pt-Co-ZrO2/MWCNTs underwent only 24.5% degradation in maximum power density after 30,000 accelerated durability tests (ADTs). However, the MEA with Pt/C after 30,000 ADTs exhibited 39.6% performance loss in maximum power density. The enhanced mass activity and catalytic durability of Pt-Co-ZrO2/MWCNTs could be attributed to the core-shell Pt-Co alloy NPs with Pt-rich surface and the interface effect between Pt-Co alloy NPs and oxygen vacancy-rich ZrO2 NPs. In addition, this research also provided a solution to the durability issue of cathodes without sacrificing ORR mass activity, which would promote practical application of PEMFCs. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.