In Situ Nitrogen Infiltration into an Ordered Pt<sub>3</sub>Co Alloy with sp–d Hybridization to Boost Fuel Cell Performance
Mengzhao Zhu, Huijuan Zhang, Yanmin Hu, Fangyao Zhou, Xiaoping Gao, Dayin He, Xuyan Zhao, Chao Zhao, Jing Wang, Wenan Tie, Xiaoyan Tian, Bo Wang, Tao Yao, Huang Zhou, Zhe Wang, Jin Wang, Wenxin Guo, Yuen Wu
Abstract
Reducing the dosage of Pt while achieving high activity and stability remains a significant challenge in developing a cathode catalyst for the H 2 /air-fed fuel cell. Here, we employed N-doped carbon derived from small organic molecules as N sources to prepare a fully N-doped ordered Pt 3 Co catalyst (IM-Pt 3 CoN) for the oxygen reduction reaction (ORR). This unique approach precisely controls the in situ capture of N atoms during the high-temperature alloying process of ordered Pt 3 Co nanoparticles (NPs), allowing full interstitial doping of N atoms within the gaps of Pt 3 Co intermetallic nanocrystals. The nitrogen-implanted IM-Pt 3 Co with increased vacancy formation energy of Pt/Co and optimized d band can restrain the tendency of Pt/Co dissolution and weaken the binding of oxygenated species, leading to improved ORR activity and durability. Remarkably, the IM-Pt 3 CoN catalyst demonstrated high performance in the H 2 –O 2 fuel cell (a high power density of 2.4 W cm –2, 1.21 A/mg Pt for mass activity (MA)) and enhanced stability (78.7% MA retained after 30k voltage cycles). Furthermore, in practical H 2 –air fuel cell tests, a peak power density of 1.01 W cm –2 and a voltage loss of only 28 mV at 0.8 A cm –2 after an accelerated durability test (ADT) can be achieved. These performance indicators exceed the Department of Energy (DOE) 2025 fuel cell technical targets.