Abstract
The development of highly efficient and stable electrocatalysts with minimized noble metal loading is crucial for advancing oxygen reduction reaction (ORR) technology in alkaline fuel cells. Herein, we fabricated a quaternary catalyst comprising PdPt nanoalloys on CoNi mixed oxide matrix (denoted as PdPt-CoNi) with an ultra-low Pt content of ∼ 2 wt%. As-prepared PdPt-CoNi catalyst achieves a remarkable mass activity of 3250 mA mg(Pt)(-1) at 0.85 V vs. RHE and 635 mA mg(Pt)(-1) at 0.90 V vs. RHE in alkaline ORR (0.1 M KOH), surpassing the performance of the commercial J.M.-Pt/C (20 wt%) catalyst by approximately 48 and 28 times, respectively, at 0.85 V vs. RHE and 0.90 V vs. RHE. More importantly, the PdPt-CoNi catalyst demonstrates remarkable long-term stability, retaining 100% of its initial activity even after 20,000 accelerated durability test (ADT) cycles, showcasing its long-term durability under the harsh redox environment. Utilizing in-situ X-ray absorption spectroscopy at the Co, Ni, Pd, and Pt edges, we revealed that the exceptional ORR performance of the PtPd-CoNi catalyst stems from the strong metal-support interaction between PtPd nanoalloys and the CoNi mixed-oxide support, where Co and Ni domains serve as the electron donor to the surface Pd/Pt sites. Comparative studies reveal that carbon-supported PdPt nanoalloys with a similar metal loading suffer a significant decline in ORR activity, showing reductions of approximately 68% at 0.85 V and 80% at 0.90 V vs. RHE. This work highlights the synergistic effects of PdPt nanoalloys and CoNi-mixed oxides in promoting ORR kinetics while ensuring outstanding stability, paving the way for next-generation electrocatalysts with minimal noble metal utilization.