Pd<sub>1</sub>Ni<sub>2</sub> Trimer Sites Drive Efficient and Durable Hydrogen Oxidation in Alkaline Media
Shuqi Wang, Ze‐Cheng Yao, Zhuo‐Qi Shi, Xuerui Liu, Tang Tang, Hairui Pan, Lirong Zheng, Qinghua Zhang, Dong Su, Zhongbin Zhuang, Lu Zhao, Qi An, Jin‐Song Hu
Abstract
Anion-exchange membrane fuel cell (AEMFC) is a cost-effective hydrogen-to-electricity conversion technology under a zero-emission scenario. However, the sluggish kinetics of the anodic hydrogen oxidation reaction (HOR) impedes the commercial implementation of AEMFCs. Here, we develop a Pd single-atom-embedded Ni 3 N catalyst (Pd 1 /Ni 3 N) with unconventional Pd 1 Ni 2 trimer sites to drive efficient and durable HOR in alkaline media. Integrating theoretical and experimental analyses, we demonstrate that dual Pd 1 Ni 2 sites achieve a “*H on Pd 1 Ni 2 –H V + *OH on Pd 1 Ni 2 –H N ” adsorption mode, effectively weakening the overstrong *H and *OH adsorptions on pristine Ni 3 N. Owing to the unique coordination mode and atomically dispersed catalytic sites, the resulting Pd 1 /Ni 3 N catalyst delivers a high intrinsic and mass activity together with excellent antioxidation capability and CO tolerance. Specifically, the HOR mass activity of Pd 1 /Ni 3 N reaches 7.54 A mg Pd –1 at the overpotential of 50 mV. The AEMFC employing Pd 1 /Ni 3 N as the anode catalyst displays a high power density of 31.7 W mg Pd –1 with an ultralow anode precious metal loading of only 0.023 mg Pd cm –2 . This study provides guidance for the design of high-performance alkaline HOR catalytic sites at the atomic level.