Synergizing Mo Single Atoms and Mo2 C Nanoparticles on CNTs Synchronizes Selectivity and Activity of Electrocatalytic N2 Reduction to Ammonia

Yuanyuan Ma; Tong Yang; Haiyuan Zou; Wenjie Zang; Zongkui Kou; Lu Mao; Yuanping Feng; Lei Shen; Stephen J Pennycook; Lele Duan; Xu Li; John Wang

doi:10.1002/adma.202002177

Synergizing Mo Single Atoms and Mo₂ C Nanoparticles on CNTs Synchronizes Selectivity and Activity of Electrocatalytic N₂ Reduction to Ammonia

Adv Mater. 2020 Aug;32(33):e2002177. doi: 10.1002/adma.202002177. Epub 2020 Jul 6.

Authors

Yuanyuan Ma^{1

2}, Tong Yang³, Haiyuan Zou⁴, Wenjie Zang¹, Zongkui Kou¹, Lu Mao², Yuanping Feng³, Lei Shen⁵, Stephen J Pennycook¹, Lele Duan⁴, Xu Li², John Wang¹

Affiliations

¹ Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore, 117574, Singapore.
² Institute of Materials Research and Engineering, Agency for Science Technology and Research (A* STAR), Singapore, 138634, Singapore.
³ Department of Physics, National University of Singapore, Singapore, 117551, Singapore.
⁴ Department of Chemistry and Shenzhen Grubbs Institute, Southern University of Science and Technology (SUSTech), Shenzhen, 518055, China.
⁵ Department of Mechanical Engineering, National University of Singapore, Singapore, 117575, Singapore.

PMID: 32627888
DOI: 10.1002/adma.202002177

Abstract

Previous research of molybdenum-based electrocatalysts for nitrogen reduction reaction (NRR) has been largely considered on either isolated Mo single atoms (MoSAs) or Mo carbide particles (e.g., Mo₂ C) separately, while an integrated synergy (MoSAs-Mo₂ C) of the two has never been considered. The theoretical calculations show that the Mo single atoms and Mo₂ C nanoparticles exhibit, respectively, different catalytic hydrogen evolution reaction and NRR selectivity. Therefore, a new role-playing synergistic mechanism can be well enabled for the multistep NRR, when the two are combined on the same N-doped carbon nanotubes (NCNTs). This hypothesis is confirmed experimentally, where the MoSAs-Mo₂ C assembled on NCNTs (MoSAs-Mo₂ C/NCNTs) yields an ammonia formation rate of 16.1 µg h^-1 cm_cat ^-2 at -0.25 V versus reversible hydrogen electrode, which is about four times that by the Mo₂ C alone (Mo₂ C/NCNTs) and 4.5 times that by the MoSAs alone (MoSAs/NCNTs). Moreover, the Faradic efficiency of the MoSAs-Mo₂ C/NCNTs is raised up to twofold and sevenfold of the Mo₂ C/NCNTs and MoSAs/NCNTs, respectively. The MoSAs-Mo₂ C/NCNTs also demonstrate outstanding stability by the almost unchanged catalytic performance over 10 h of the chronoamperometric test. The present study provides a promising new prototype of synchronizing the selectivity and activity for the multistep catalytic reactions.

Keywords: Mo2C; ammonia production; electrocatalysts; nitrogen reduction reaction; single atom catalysts.

Abstract

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