Dual-Metal Sites Boosting Polarization of Nitrogen Molecules for Efficient Nitrogen Photofixation

摘要

Constructing nitrogen (N-2) adsorption and activation sites on semiconductors is the key to achieving efficient N-2 photofixation. Herein, Mn-W dual-metal sites on WO3 are designed toward efficient N-2 photoreduction via controlled Mn doping. Impressively, the optimal 2.3% Mn-doped WO3 (Mn-WO3) exhibits a remarkable ammonia (NH3) production rate of 425 mu mol g(cat.)(-1) h(-1), representing the best catalytic performance among the ever-reported tungsten oxide-based photocatalysts for N-2 fixation. Quasi in situ synchrotron radiation X-ray spectroscopy directly identifies that the Mn-W dual-metal sites can enhance the polarization of the adsorbed N-2, which is beneficial to the N-2 activation. Further theoretical calculations reveal that the increased polarization is originated from the electron back-donation into the antibonding orbitals of the adsorbed N-2, hence lowering the reaction energy barrier toward the N-2 photofixation. The concept of dual sites construction for inert molecule activation offers a powerful platform toward rational design of highly efficient catalysts for nitrogen fixation and beyond.

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