Atomic-scale evidence for highly selective electrocatalytic N-N coupling on metallic MoS2

Daoping He; Hideshi Ooka; Yujeong Kim; Yamei Li; Fangming Jin; Sun Hee Kim; Ryuhei Nakamura

doi:10.1073/pnas.2008429117

Atomic-scale evidence for highly selective electrocatalytic N-N coupling on metallic MoS₂

Proc Natl Acad Sci U S A. 2020 Dec 15;117(50):31631-31638. doi: 10.1073/pnas.2008429117. Epub 2020 Nov 30.

Authors

Daoping He^{1

2

3}, Hideshi Ooka¹, Yujeong Kim^{4

5}, Yamei Li², Fangming Jin⁶, Sun Hee Kim^{7

5}, Ryuhei Nakamura^{8

2}

Affiliations

¹ Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan.
² Earth-Life Science Institute, Tokyo Institute of Technology, 152-8550 Tokyo, Japan.
³ School of Environmental Science and Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
⁴ Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Republic of Korea.
⁵ Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea.
⁶ School of Environmental Science and Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China; fmjin@sjtu.edu.cn shkim7@kbsi.re.kr ryuhei.nakamura@riken.jp.
⁷ Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Republic of Korea; fmjin@sjtu.edu.cn shkim7@kbsi.re.kr ryuhei.nakamura@riken.jp.
⁸ Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan; fmjin@sjtu.edu.cn shkim7@kbsi.re.kr ryuhei.nakamura@riken.jp.

Abstract

Molybdenum sulfide (MoS₂) is the most widely studied transition-metal dichalcogenide (TMDs) and phase engineering can markedly improve its electrocatalytic activity. However, the selectivity toward desired products remains poorly explored, limiting its application in complex chemical reactions. Here we report how phase engineering of MoS₂ significantly improves the selectivity for nitrite reduction to nitrous oxide, a critical process in biological denitrification, using continuous-wave and pulsed electron paramagnetic resonance spectroscopy. We reveal that metallic 1T-MoS₂ has a protonation site with a pK_a of ∼5.5, where the proton is located ∼3.26 Å from redox-active Mo site. This protonation site is unique to 1T-MoS₂ and induces sequential proton-electron transfer which inhibits ammonium formation while promoting nitrous oxide production, as confirmed by the pH-dependent selectivity and deuterium kinetic isotope effect. This is atomic-scale evidence of phase-dependent selectivity on MoS₂, expanding the application of TMDs to selective electrocatalysis.

Keywords: ENDOR spectroscopy; denitrification; electrochemistry; molybdenum sulfide; phase transitions.

Publication types

Research Support, Non-U.S. Gov't