@article{9a2927649eee4334af2f0e55666548f2,
title = "Cathodic NH4+leaching of nitrogen impurities in CoMo thin-film electrodes in aqueous acidic solutions",
abstract = "Electrocatalytic reduction of dinitrogen (N2) to ammonium (NH4+) in acidic aqueous solutions was investigated at ambient temperature and pressure using a cobalt-molybdenum (CoMo) thin-film electrode prepared by magnetron reactive sputtering. Increased concentrations of ammonium ions (NH4+) were consistently detected in the electrolyte using ion chromatography (IC) after constant-potential electrolysis at various potentials (≤−0.29 Vvs.RHE). Using a newly developed analytical method based on ammonia derivatization, performing the experiments with15N2-labelled gas led however to the detection of increased14NH4+concentrations instead of15NH4+. X-ray photoelectron spectroscopic (XPS) analysis of the electrode surface revealed the presence of Mo-N and Mo-NHxspecies. Several contamination sources were identified that led to substantial increases in the concentration of ammonium ions, including15NH3impurities in15N2gas. The observed ammonium concentrations can be consistently ascribed to leaching of nitrogen (14N) impurities incorporated in the CoMo film during the sputtering process. Researchers in the field are therefore urged to adopt extended protocols to identify and eliminate sources of ammonia contamination and to very carefully monitor the ammonium concentrations in each experimental step.",
author = "Weilai Yu and Pakpoom Buabthong and Read, {Carlos G.} and Dalleska, {Nathan F.} and Lewis, {Nathan S.} and Lewerenz, {Hans Joachim} and Gray, {Harry B.} and Katharina Brinkert",
note = "Funding Information: K. B. acknowledges funding from the fellowship program of the German National Academy of Sciences - Leopoldina, grant LPDS 2016-06. Acknowledgment is made to the donors of The American Chemical Society Petroleum Research Fund for partial support of this research. Sample preparation and analyses were performed at the Joint Center for Artificial Photosynthesis, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, which also provided support for N. S. L., W. Y., P. B. and C. G. R. We acknowledge use of instrumentation in the Molecular Materials Research Center of the Beckman Institute at Caltech. N. F. D. is grateful to the Linde Center for support. The Environmental Analysis Center is supported by the Beckman Institute at Caltech. W. Y. and C. G. R. acknowledge the Resnick Sustainability Institute at Caltech for fellowship support. Dr Fabai Wu and Prof. Victoria Orphan are acknowledged for providing the15NH4Cl standard reagent for UPLC-MS analysis. Mr Christopher Kenseth is thanked for assistance with UPLC-MS analysis. Dr Yuanlong Huang is acknowledged for assistance with chemiluminescence analysis. All authors would like to acknowledge the reviewers for their valuable comments in the first round. Funding Information: K. B. acknowledges funding from the fellowship program of the German National Academy of Sciences – Leopoldina, grant LPDS 2016-06. Acknowledgment is made to the donors of The American Chemical Society Petroleum Research Fund for partial support of this research. Sample preparation and analyses were performed at the Joint Center for Articial Photosynthesis, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993, which also provided support for N. S. L., W. Y., P. B. and C. G. R. We acknowledge use of instrumentation in the Molecular Materials Research Center of the Beckman Institute at Caltech. N. F. D. is grateful to the Linde Center for support. The Environmental Analysis Center is supported by the Beckman Institute at Caltech. W. Y. and C. G. R. acknowledge the Resnick Sustainability Institute at Caltech for fellowship support. Dr Fabai Wu and Prof. Victoria Orphan are acknowledged for providing the 15NH4Cl standard reagent for UPLC-MS analysis. Mr Christopher Kenseth is thanked for assistance with UPLC-MS analysis. Dr Yuanlong Huang is acknowledged for assistance with chemiluminescence analysis. All authors would like to acknowledge the reviewers for their valuable comments in the rst round. Publisher Copyright: {\textcopyright} The Royal Society of Chemistry 2020.",
year = "2020",
month = oct,
doi = "10.1039/d0se00674b",
language = "English",
volume = "4",
pages = "5080--5087",
journal = "Sustainable Energy and Fuels",
issn = "2398-4902",
publisher = "Royal Society of Chemistry",
number = "10",
}