Crystal structures of molybdenum borides dictate electrocatalytic ammonia synthesis efficiency

Guiming Peng; Jian Wen Zhao; Jiaqi Wang; Eli Hoenig; Suqin Wu; Mingzhan Wang; Mao He; Lei Zhang; Jin Xun Liu; Chong Liu

doi:10.1016/j.apcatb.2023.123020

Crystal structures of molybdenum borides dictate electrocatalytic ammonia synthesis efficiency

Guiming Peng, Jian Wen Zhao, Jiaqi Wang, Eli Hoenig, Suqin Wu, Mingzhan Wang, Mao He, Lei Zhang, Jin Xun Liu, Chong Liu

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

Abstract

Rather than multivalence molybdenum (Mo), the low valence Mo has rarely been reported as active site for nitrogen reduction. Herein, molybdenum borides with various Mo-B stoichiometry ratios (Mo₂B, α-MoB, and Mo₂B₄) in which Mo shows low valence (<1) are synthesized as electrochemical nitrogen reduction reaction (eNRR) catalysts. Mo₂B₄ demonstrates the highest NH₃ yield of 7.65 µg h^{− 1}/mg at − 0.15 V with Faradaic efficiency (FE) of 12.47 %, while α-MoB exhibits the fastest intrinsic eNRR reaction rate with a higher FE of 17.17 % after considering electrochemically active surface area. DFT calculations reveal that both enzymatic and consecutive mechanisms via side-on configuration can proceed on α-MoB. Additionally, α-MoB exhibits suppressed HER activity due to an optimal surface B occupancy. The eNRR of molybdenum borides were verified qualitatively and quantitatively by ¹⁵N₂ isotope experiments. This study demonstrated a synergistic design of eNRR and HER activity to achieve efficient electrocatalytic ammonia production with high eNRR selectivity.

Original language	English
Article number	123020
Journal	Applied Catalysis B: Environmental
Volume	338
DOIs	https://doi.org/10.1016/j.apcatb.2023.123020
State	Published - 5 Dec 2023
Externally published	Yes

Keywords

Catalyst design
Electrochemical synthesis
Molybdenum boride
Nitrogen reduction

ASJC Scopus subject areas

Catalysis
General Environmental Science
Process Chemistry and Technology

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10.1016/j.apcatb.2023.123020

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title = "Crystal structures of molybdenum borides dictate electrocatalytic ammonia synthesis efficiency",

abstract = "Rather than multivalence molybdenum (Mo), the low valence Mo has rarely been reported as active site for nitrogen reduction. Herein, molybdenum borides with various Mo-B stoichiometry ratios (Mo2B, α-MoB, and Mo2B4) in which Mo shows low valence (<1) are synthesized as electrochemical nitrogen reduction reaction (eNRR) catalysts. Mo2B4 demonstrates the highest NH3 yield of 7.65 µg h− 1/mg at − 0.15 V with Faradaic efficiency (FE) of 12.47 %, while α-MoB exhibits the fastest intrinsic eNRR reaction rate with a higher FE of 17.17 % after considering electrochemically active surface area. DFT calculations reveal that both enzymatic and consecutive mechanisms via side-on configuration can proceed on α-MoB. Additionally, α-MoB exhibits suppressed HER activity due to an optimal surface B occupancy. The eNRR of molybdenum borides were verified qualitatively and quantitatively by 15N2 isotope experiments. This study demonstrated a synergistic design of eNRR and HER activity to achieve efficient electrocatalytic ammonia production with high eNRR selectivity.",

keywords = "Catalyst design, Electrochemical synthesis, Molybdenum boride, Nitrogen reduction",

author = "Guiming Peng and Zhao, {Jian Wen} and Jiaqi Wang and Eli Hoenig and Suqin Wu and Mingzhan Wang and Mao He and Lei Zhang and Liu, {Jin Xun} and Chong Liu",

note = "Publisher Copyright: {\textcopyright} 2023 Elsevier B.V.",

year = "2023",

month = dec,

day = "5",

doi = "10.1016/j.apcatb.2023.123020",

language = "English",

volume = "338",

journal = "Applied Catalysis B: Environmental",

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T1 - Crystal structures of molybdenum borides dictate electrocatalytic ammonia synthesis efficiency

AU - Peng, Guiming

AU - Zhao, Jian Wen

AU - Wang, Jiaqi

AU - Hoenig, Eli

AU - Wu, Suqin

AU - Wang, Mingzhan

AU - He, Mao

AU - Zhang, Lei

AU - Liu, Jin Xun

AU - Liu, Chong

PY - 2023/12/5

Y1 - 2023/12/5

N2 - Rather than multivalence molybdenum (Mo), the low valence Mo has rarely been reported as active site for nitrogen reduction. Herein, molybdenum borides with various Mo-B stoichiometry ratios (Mo2B, α-MoB, and Mo2B4) in which Mo shows low valence (<1) are synthesized as electrochemical nitrogen reduction reaction (eNRR) catalysts. Mo2B4 demonstrates the highest NH3 yield of 7.65 µg h− 1/mg at − 0.15 V with Faradaic efficiency (FE) of 12.47 %, while α-MoB exhibits the fastest intrinsic eNRR reaction rate with a higher FE of 17.17 % after considering electrochemically active surface area. DFT calculations reveal that both enzymatic and consecutive mechanisms via side-on configuration can proceed on α-MoB. Additionally, α-MoB exhibits suppressed HER activity due to an optimal surface B occupancy. The eNRR of molybdenum borides were verified qualitatively and quantitatively by 15N2 isotope experiments. This study demonstrated a synergistic design of eNRR and HER activity to achieve efficient electrocatalytic ammonia production with high eNRR selectivity.

AB - Rather than multivalence molybdenum (Mo), the low valence Mo has rarely been reported as active site for nitrogen reduction. Herein, molybdenum borides with various Mo-B stoichiometry ratios (Mo2B, α-MoB, and Mo2B4) in which Mo shows low valence (<1) are synthesized as electrochemical nitrogen reduction reaction (eNRR) catalysts. Mo2B4 demonstrates the highest NH3 yield of 7.65 µg h− 1/mg at − 0.15 V with Faradaic efficiency (FE) of 12.47 %, while α-MoB exhibits the fastest intrinsic eNRR reaction rate with a higher FE of 17.17 % after considering electrochemically active surface area. DFT calculations reveal that both enzymatic and consecutive mechanisms via side-on configuration can proceed on α-MoB. Additionally, α-MoB exhibits suppressed HER activity due to an optimal surface B occupancy. The eNRR of molybdenum borides were verified qualitatively and quantitatively by 15N2 isotope experiments. This study demonstrated a synergistic design of eNRR and HER activity to achieve efficient electrocatalytic ammonia production with high eNRR selectivity.

KW - Catalyst design

KW - Electrochemical synthesis

KW - Molybdenum boride

KW - Nitrogen reduction

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M3 - Article

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JF - Applied Catalysis B: Environmental

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ER -

Crystal structures of molybdenum borides dictate electrocatalytic ammonia synthesis efficiency

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Keywords

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