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Title: Elementary kinetics of nitrogen electroreduction on Fe surfaces

Abstract

Electrochemical ammonia synthesis could provide a sustainable and efficient alternative to the energy intensive Haber-Bosch process. Development of an active and selective N 2 electroreduction catalyst requires mechanism determination to aid in connecting catalyst composition and structure to performance. Density functional theory calculations are used to examine the elementary step energetics of associative N 2 reduction mechanisms on two low index Fe surfaces. Interfacial water molecules in the Heyrovsky-like mechanism help lower some of the elementary activation barriers. Electrode potential dependent barriers show that cathodic potentials below -1.5 V-RHE are necessary to give a significant rate of N 2 electroreduction. DFT barriers suggest a larger overpotential than expected based on elementary reaction free energies. Linear Brønsted-Evans-Polanyi relationships do not hold across N–H formation steps on these surfaces, further confirming that explicit barriers should be considered in DFT studies of the nitrogen reduction reaction.

Authors:
 [1];  [2];  [1]
  1. Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering
  2. Univ. of North Carolina, Wilmington, NC (United States). Dept. of Chemistry and Biochemistry
Publication Date:
Research Org.:
Pennsylvania State Univ., University Park, PA (United States); Univ. of North Carolina, Wilmington, NC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1482070
Grant/Contract Number:  
SC0016529; ACI-1053575; DGE-1449785
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 150; Journal Issue: 4; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Maheshwari, Sharad, Rostamikia, Gholamreza, and Janik, Michael J. Elementary kinetics of nitrogen electroreduction on Fe surfaces. United States: N. p., 2018. Web. doi:10.1063/1.5048036.
Maheshwari, Sharad, Rostamikia, Gholamreza, & Janik, Michael J. Elementary kinetics of nitrogen electroreduction on Fe surfaces. United States. doi:10.1063/1.5048036.
Maheshwari, Sharad, Rostamikia, Gholamreza, and Janik, Michael J. Thu . "Elementary kinetics of nitrogen electroreduction on Fe surfaces". United States. doi:10.1063/1.5048036.
@article{osti_1482070,
title = {Elementary kinetics of nitrogen electroreduction on Fe surfaces},
author = {Maheshwari, Sharad and Rostamikia, Gholamreza and Janik, Michael J.},
abstractNote = {Electrochemical ammonia synthesis could provide a sustainable and efficient alternative to the energy intensive Haber-Bosch process. Development of an active and selective N2 electroreduction catalyst requires mechanism determination to aid in connecting catalyst composition and structure to performance. Density functional theory calculations are used to examine the elementary step energetics of associative N2 reduction mechanisms on two low index Fe surfaces. Interfacial water molecules in the Heyrovsky-like mechanism help lower some of the elementary activation barriers. Electrode potential dependent barriers show that cathodic potentials below -1.5 V-RHE are necessary to give a significant rate of N2 electroreduction. DFT barriers suggest a larger overpotential than expected based on elementary reaction free energies. Linear Brønsted-Evans-Polanyi relationships do not hold across N–H formation steps on these surfaces, further confirming that explicit barriers should be considered in DFT studies of the nitrogen reduction reaction.},
doi = {10.1063/1.5048036},
journal = {Journal of Chemical Physics},
number = 4,
volume = 150,
place = {United States},
year = {2018},
month = {11}
}

Journal Article:
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Works referenced in this record:

Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set
journal, July 1996


A climbing image nudged elastic band method for finding saddle points and minimum energy paths
journal, December 2000

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