Nitrogenase-mimic iron-containing chalcogels for photochemical reduction of dinitrogen to ammonia [electronic resource].
- Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages 5,530-5,535 : digital, PDF file
- Additional Creators:
- United States. Department of Energy. Office of Basic Energy Sciences
United States. Department of Energy. Office of Scientific and Technical Information
- A nitrogenase-inspired biomimetic chalcogel system comprising double-cubane [Mo<sub>2</sub>Fe<sub>6</sub>S<sub>8</sub>(SPh)<sub>3</sub>] and single-cubane (Fe<sub>4</sub>S<sub>4</sub>) biomimetic clusters demonstrates photocatalytic N<sub>2</sub> fixation and conversion to NH<sub>3</sub> in ambient temperature and pressure conditions. Replacing the Fe<sub>4</sub>S<sub>4</sub> clusters in this system with other inert ions such as Sb<sup>3+</sup>, Sn<sup>4+</sup>, Zn<sup>2+</sup> also gave chalcogels that were photocatalytically active. Finally, molybdenum-free chalcogels containing only Fe<sub>4</sub>S<sub>4</sub> clusters are also capable of accomplishing the N2 fixation reaction with even higher efficiency than their Mo<sub>2</sub>Fe<sub>6</sub>S<sub>8</sub>(SPh)<sub>3</sub>-containing counterparts. In this study, our results suggest that redox-active iron-sulfide–containing materials can activate the N<sub>2</sub> molecule upon visible light excitation, which can be reduced all of the way to NH<sub>3</sub> using protons and sacrificial electrons in aqueous solution. Evidently, whereas the Mo<sub>2</sub>Fe<sub>6</sub>S<sub>8</sub>(SPh)<sub>3</sub> is capable of N<sub>2</sub> fixation, Mo itself is not necessary to carry out this process. The initial binding of N<sub>2</sub> with chalcogels under illumination was observed with in situ diffuse-reflectance Fourier transform infrared spectroscopy (DRIFTS). <sup>15</sup>N<sub>2</sub> isotope experiments confirm that the generated NH<sub>3</sub> derives from N<sub>2</sub>. Density functional theory (DFT) electronic structure calculations suggest that the N<sub>2</sub> binding is thermodynamically favorable only with the highly reduced active clusters. Finally, the results reported herein contribute to ongoing efforts of mimicking nitrogenase in fixing nitrogen and point to a promising path in developing catalysts for the reduction of N<sub>2</sub> under ambient conditions.
- Published through SciTech Connect.
Proceedings of the National Academy of Sciences of the United States of America 113 20 ISSN 0027-8424 AM
Jian Liu; Matthew S. Kelley; Weiqiang Wu; Abhishek Banerjee; Alexios P. Douvalis; Jinsong Wu; Yongbo Zhang; George C. Schatz; Mercouri G. Kanatzidis.
Northwestern Univ., Evanston, IL (United States)
- Funding Information:
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