Dissociative and Associative Concerted Mechanism for Ammonia Synthesis over Co-Based Catalyst

Tian-Nan Ye; Sang-Won Park; Yangfan Lu; Jiang Li; Jiazhen Wu; Masato Sasase; Masaaki Kitano; Hideo Hosono

doi:10.1021/jacs.1c06657

Dissociative and Associative Concerted Mechanism for Ammonia Synthesis over Co-Based Catalyst

J Am Chem Soc. 2021 Aug 18;143(32):12857-12866. doi: 10.1021/jacs.1c06657. Epub 2021 Aug 9.

Authors

Tian-Nan Ye^{1

2}, Sang-Won Park^{1

3}, Yangfan Lu^{1

4

5}, Jiang Li¹, Jiazhen Wu^{1

6}, Masato Sasase¹, Masaaki Kitano^{1

7}, Hideo Hosono^{1

3}

Affiliations

¹ Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
² Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
³ International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
⁴ College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China.
⁵ National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China.
⁶ Department of Materials Science and Engineering, Southern University of Science and Technology, 1088 Xueyuan Blvd., Nanshan District, Shenzhen, Guangdong 518055, China.
⁷ Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.

PMID: 34369762
DOI: 10.1021/jacs.1c06657

Abstract

The current catalytic reaction mechanism for ammonia synthesis relies on either dissociative or associative routes, in which adsorbed N₂ dissociates directly or is hydrogenated step-by-step until it is broken upon the release of NH₃ through associative adsorption. Here, we propose a concerted mechanism of associative and dissociative routes for ammonia synthesis over a cobalt-loaded nitride catalyst. Isotope exchange experiments reveal that the adsorbed N₂ can be activated on both Co metal and the nitride support, which leads to superior low-temperature catalytic performance. The cooperation of the surface low work function (2.6 eV) feature and the formation of surface nitrogen vacancies on the CeN support gives rise to a dual pathway for N₂ activation with much reduced activation energy (45 kJ·mol^-1) over that of Co-based catalysts reported so far, which results in efficient ammonia synthesis under mild conditions.