Ambient Electrochemical Ammonia Synthesis with High Selectivity on Fe/Fe Oxide Catalyst

Lin Hu; Asim Khaniya; Jun Wang; Gang Chen; William E. Kaden; Xiaofeng Feng

doi:10.1021/acscatal.8b02585

Ambient Electrochemical Ammonia Synthesis with High Selectivity on Fe/Fe Oxide Catalyst

Lin Hu, Asim Khaniya, Jun Wang, Gang Chen, William E. Kaden, Xiaofeng Feng

University of Central Florida

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

269 Scopus citations

Abstract

Electrochemical reduction of N₂ to NH₃ under ambient conditions can provide an alternative to the Haber-Bosch process for distributed NH₃ production that can be powered by renewable electricity. The major challenge for realizing such a process is to develop efficient electrocatalysts for the N₂ reduction reaction (N₂RR), as typical catalysts show a low activity and selectivity due to the barrier for N₂ activation and the competing hydrogen evolution reaction (HER). Here we report an Fe/Fe₃O₄ catalyst for ambient electrochemical NH₃ synthesis, which was prepared by oxidizing an Fe foil at 300 °C followed by in situ electrochemical reduction. The Fe/Fe₃O₄ catalyst exhibits a Faradaic efficiency of 8.29% for NH₃ production at -0.3 V vs the reversible hydrogen electrode in phosphate buffer solution, which is around 120 times higher than that of the original Fe foil. The high selectivity is enabled by an enhancement of the intrinsic (surface-area-normalized) N₂RR activity by up to 9-fold as well as an effective suppression of the HER activity. The N₂RR selectivity of the Fe/Fe₃O₄ catalyst is also higher than that of Fe, Fe₃O₄, and Fe₂O₃ nanoparticles, suggesting Fe/Fe oxide composite to be an efficient catalyst for ambient electrochemical NH₃ synthesis.

Original language	English
Pages (from-to)	9312-9319
Number of pages	8
Journal	ACS Catalysis
Volume	8
Issue number	10
DOIs	https://doi.org/10.1021/acscatal.8b02585
State	Published - Oct 5 2018
Externally published	Yes

Scopus Subject Areas

Catalysis
General Chemistry

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title = "Ambient Electrochemical Ammonia Synthesis with High Selectivity on Fe/Fe Oxide Catalyst",

abstract = "Electrochemical reduction of N2 to NH3 under ambient conditions can provide an alternative to the Haber-Bosch process for distributed NH3 production that can be powered by renewable electricity. The major challenge for realizing such a process is to develop efficient electrocatalysts for the N2 reduction reaction (N2RR), as typical catalysts show a low activity and selectivity due to the barrier for N2 activation and the competing hydrogen evolution reaction (HER). Here we report an Fe/Fe3O4 catalyst for ambient electrochemical NH3 synthesis, which was prepared by oxidizing an Fe foil at 300 °C followed by in situ electrochemical reduction. The Fe/Fe3O4 catalyst exhibits a Faradaic efficiency of 8.29% for NH3 production at -0.3 V vs the reversible hydrogen electrode in phosphate buffer solution, which is around 120 times higher than that of the original Fe foil. The high selectivity is enabled by an enhancement of the intrinsic (surface-area-normalized) N2RR activity by up to 9-fold as well as an effective suppression of the HER activity. The N2RR selectivity of the Fe/Fe3O4 catalyst is also higher than that of Fe, Fe3O4, and Fe2O3 nanoparticles, suggesting Fe/Fe oxide composite to be an efficient catalyst for ambient electrochemical NH3 synthesis.",

author = "Lin Hu and Asim Khaniya and Jun Wang and Gang Chen and Kaden, {William E.} and Xiaofeng Feng",

note = "Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",

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T1 - Ambient Electrochemical Ammonia Synthesis with High Selectivity on Fe/Fe Oxide Catalyst

AU - Hu, Lin

AU - Khaniya, Asim

AU - Wang, Jun

AU - Chen, Gang

AU - Kaden, William E.

AU - Feng, Xiaofeng

PY - 2018/10/5

Y1 - 2018/10/5

N2 - Electrochemical reduction of N2 to NH3 under ambient conditions can provide an alternative to the Haber-Bosch process for distributed NH3 production that can be powered by renewable electricity. The major challenge for realizing such a process is to develop efficient electrocatalysts for the N2 reduction reaction (N2RR), as typical catalysts show a low activity and selectivity due to the barrier for N2 activation and the competing hydrogen evolution reaction (HER). Here we report an Fe/Fe3O4 catalyst for ambient electrochemical NH3 synthesis, which was prepared by oxidizing an Fe foil at 300 °C followed by in situ electrochemical reduction. The Fe/Fe3O4 catalyst exhibits a Faradaic efficiency of 8.29% for NH3 production at -0.3 V vs the reversible hydrogen electrode in phosphate buffer solution, which is around 120 times higher than that of the original Fe foil. The high selectivity is enabled by an enhancement of the intrinsic (surface-area-normalized) N2RR activity by up to 9-fold as well as an effective suppression of the HER activity. The N2RR selectivity of the Fe/Fe3O4 catalyst is also higher than that of Fe, Fe3O4, and Fe2O3 nanoparticles, suggesting Fe/Fe oxide composite to be an efficient catalyst for ambient electrochemical NH3 synthesis.

AB - Electrochemical reduction of N2 to NH3 under ambient conditions can provide an alternative to the Haber-Bosch process for distributed NH3 production that can be powered by renewable electricity. The major challenge for realizing such a process is to develop efficient electrocatalysts for the N2 reduction reaction (N2RR), as typical catalysts show a low activity and selectivity due to the barrier for N2 activation and the competing hydrogen evolution reaction (HER). Here we report an Fe/Fe3O4 catalyst for ambient electrochemical NH3 synthesis, which was prepared by oxidizing an Fe foil at 300 °C followed by in situ electrochemical reduction. The Fe/Fe3O4 catalyst exhibits a Faradaic efficiency of 8.29% for NH3 production at -0.3 V vs the reversible hydrogen electrode in phosphate buffer solution, which is around 120 times higher than that of the original Fe foil. The high selectivity is enabled by an enhancement of the intrinsic (surface-area-normalized) N2RR activity by up to 9-fold as well as an effective suppression of the HER activity. The N2RR selectivity of the Fe/Fe3O4 catalyst is also higher than that of Fe, Fe3O4, and Fe2O3 nanoparticles, suggesting Fe/Fe oxide composite to be an efficient catalyst for ambient electrochemical NH3 synthesis.

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Ambient Electrochemical Ammonia Synthesis with High Selectivity on Fe/Fe Oxide Catalyst

Abstract

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