Efficient NH3‑Tolerant Nickel-Based Hydrogen Oxidation Catalyst for Anion Exchange Membrane Fuel Cells

• Published in: Journal of the American Chemical Society Vol. 145; no. 31; pp. 17485 - 17494
• Main Authors: Wang, Ye-Hua, Gao, Fei-Yue, Zhang, Xiao-Long, Yang, Yu, Liao, Jie, Niu, Zhuang-Zhuang, Qin, Shuai, Yang, Peng-Peng, Yu, Peng-Cheng, Sun, Mei, Gao, Min-Rui
• Format: Journal Article
• Language: English
• Published: American Chemical Society 09.08.2023
• Subjects: adsorption; alloys; ammonia; anion-exchange membranes; carbon; catalysts; chromium; electric power; electrodes; energy; fuel cells; fuels; hydrogen; oxidation; platinum
• DOI: 10.1021/jacs.3c06903
• ISSN: 0002-7863; 1520-5126

Converting hydrogen chemical energy into electrical energy by fuel cells offers high efficiencies and environmental advantages, but ultrapure hydrogen (over 99.97%) is required; otherwise, the electrode catalysts, typically platinum on carbon (Pt/C), will be poisoned by impurity gases such as ammonia (NH3). Here we demonstrate remarkable NH3 resistivity over a nickel–molybdenum alloy (MoNi4) modulated by chromium (Cr) dopants. The resultant Cr-MoNi4 exhibits high activity toward alkaline hydrogen oxidation and can undergo 10,000 cycles without apparent activity decay in the presence of 2 ppm of NH3. Furthermore, a fuel cell assembled with this catalyst retains 95% of the initial peak power density even when NH3 (10 ppm)/H2 was fed, whereas the power output reduces to 61% of the initial value for the Pt/C catalyst. Experimental and theoretical studies reveal that the Cr modifier not only creates electron-rich states that restrain lone-pair electron donation but also downshifts the d-band center to suppress d-electron back-donation, synergistically weakening NH3 adsorption.