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XU 2021-3-16-spin-polarized OER.pdf (3.53 MB)

Spin-Polarized Oxygen Evolution Reaction Under Magnetic Field

preprint
submitted on 16.03.2021, 06:11 and posted on 17.03.2021, 05:38 by Xiao Ren, Tianze Wu, Yuanmiao Sun, Yan Li, Guoyu Xian, Xianhu Liu, Chengmin Sheng, Jose Gracia, Hong-jun Gao, Haitao Yang, Zhichuan J. Xu

The oxygen evolution reaction (OER) is the bottleneck that limits the energy efficiency of water-splitting. The process involves four electrons’ transfer and the generation of triplet state O2 from singlet state species (OH- or H2O). Recently, explicit spin selection was described as a possible way to promote OER in alkaline conditions, but the specific spin-polarized kinetics remains unclear. Here, we report that by using ferromagnetic ordered catalysts as the spin polarizer for spin selection under a constant magnetic field, the OER can be enhanced. However, it does not applicable to non-ferromagnetic catalysts. We found that the spin polarization occurs at the first electron transfer step in OER, where coherent spin exchange happens between the ferromagnetic catalyst and the adsorbed oxygen species with fast kinetics, under the principle of spin angular momentum conservation. In the next three electron transfer steps, as the adsorbed O species adopt fixed spin direction, the OER electrons need to follow the Hund rule and Pauling exclusion principle, thus to carry out spin polarization spontaneously and finally lead to the generation of triplet state O2. Here, we showcase spin-polarized kinetics of oxygen evolution reaction, which gives references in the understanding and design of spin-dependent catalysts.

History

Email Address of Submitting Author

xuzc@ntu.edu.sg

Institution

Nanyang Technological University

Country

Singapore

ORCID For Submitting Author

0000-0001-7746-5920

Declaration of Conflict of Interest

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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