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
Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
J Am Chem Soc. 2023 Aug 9;145(31):17485-17494. doi: 10.1021/jacs.3c06903. Epub 2023 Aug 1.
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 (NH). Here we demonstrate remarkable NH resistivity over a nickel-molybdenum alloy (MoNi) modulated by chromium (Cr) dopants. The resultant Cr-MoNi exhibits high activity toward alkaline hydrogen oxidation and can undergo 10,000 cycles without apparent activity decay in the presence of 2 ppm of NH. Furthermore, a fuel cell assembled with this catalyst retains 95% of the initial peak power density even when NH (10 ppm)/H 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 NH adsorption.
通过燃料电池将氢化学能转化为电能具有高效率和环境优势，但需要超纯氢（超过99.97%）；否则，电极催化剂，通常是碳载铂（Pt/C），会被诸如氨（NH）等杂质气体中毒。在此，我们展示了由铬（Cr）掺杂剂调制的镍钼合金（MoNi）具有显著的抗NH性能。所得的Cr-MoNi对碱性氢氧化表现出高活性，并且在存在2 ppm NH的情况下可经历10000次循环而无明显活性衰减。此外，用这种催化剂组装的燃料电池即使在通入NH（10 ppm）/H时仍保留初始峰值功率密度的95%，而对于Pt/C催化剂，功率输出降至初始值的61%。实验和理论研究表明，Cr改性剂不仅创造了抑制孤对电子供体的富电子状态，还使d带中心下移以抑制d电子回授，协同削弱NH吸附。
