Strong electronic coupling between CoNi mixed oxide support and PdPt nanoalloys enables highly active and durable oxygen reduction reaction.

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 at 0.85 V vs. RHE and 635 mA mg 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.