Metal bond strength regulation enables large-scale synthesis of intermetallic nanocrystals for practical fuel cells

Jiashun Liang; Yangyang Wan; Houfu Lv; Xuan Liu; Fan Lv; Shenzhou Li; Jia Xu; Zhi Deng; Junyi Liu; Siyang Zhang; Yingjun Sun; Mingchuan Luo; Gang Lu; Jiantao Han; Guoxiong Wang; Yunhui Huang; Shaojun Guo; Qing Li

doi:10.1038/s41563-024-01901-4

Metal bond strength regulation enables large-scale synthesis of intermetallic nanocrystals for practical fuel cells

Nat Mater. 2024 May 20. doi: 10.1038/s41563-024-01901-4. Online ahead of print.

Authors

Jiashun Liang^#¹, Yangyang Wan^#^{2

3}, Houfu Lv⁴, Xuan Liu¹, Fan Lv⁵, Shenzhou Li¹, Jia Xu¹, Zhi Deng¹, Junyi Liu³, Siyang Zhang¹, Yingjun Sun⁵, Mingchuan Luo⁵, Gang Lu³, Jiantao Han¹, Guoxiong Wang⁴, Yunhui Huang¹, Shaojun Guo⁶, Qing Li⁷

Affiliations

¹ State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China.
² Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang, China.
³ Department of Physics and Astronomy, California State University, Northridge, Northridge, CA, USA.
⁴ State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
⁵ School of Materials Science and Engineering, Peking University, Beijing, China.
⁶ School of Materials Science and Engineering, Peking University, Beijing, China. guosj@pku.edu.cn.
⁷ State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China. qing_li@hust.edu.cn.

^# Contributed equally.

PMID: 38769206
DOI: 10.1038/s41563-024-01901-4

Abstract

Structurally ordered L1₀-PtM (M = Fe, Co, Ni and so on) intermetallic nanocrystals, benefiting from the chemically ordered structure and higher stability, are one of the best electrocatalysts used for fuel cells. However, their practical development is greatly plagued by the challenge that the high-temperature (>600 °C) annealing treatment necessary for realizing the ordered structure usually leads to severe particle sintering, morphology change and low ordering degree, which makes it very difficult for the gram-scale preparation of desirable PtM intermetallic nanocrystals with high Pt content for practical fuel cell applications. Here we report a new concept involving the low-melting-point-metal (M' = Sn, Ga, In)-induced bond strength weakening strategy to reduce E_a and promote the ordering process of PtM (M = Ni, Co, Fe, Cu and Zn) alloy catalysts for a higher ordering degree. We demonstrate that the introduction of M' can reduce the ordering temperature to extremely low temperatures (≤450 °C) and thus enable the preparation of high-Pt-content (≥40 wt%) L1₀-Pt-M-M' intermetallic nanocrystals as well as ten-gram-scale production. X-ray spectroscopy studies, in situ electron microscopy and theoretical calculations reveal the fundamental mechanism of the Sn-facilitated ordering process at low temperatures, which involves weakened bond strength and consequently reduced E_a via Sn doping, the formation and fast diffusion of low-coordinated surface free atoms, and subsequent L1₀ nucleation. The developed L1₀-Ga-PtNi/C catalysts display outstanding performance in H₂-air fuel cells under both light- and heavy-duty vehicle conditions. Under the latter condition, the 40% L1₀-Pt₅₀Ni₃₅Ga₁₅/C catalyst delivers a high current density of 1.67 A cm^-2 at 0.7 V and retains 80% of the current density after extended 90,000 cycles, which exceeds the United States Department of Energy performance metrics and represents among the best cathodic electrocatalysts for practical proton-exchange membrane fuel cells.