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Electrochemically Induced Generation of Extraneous Nitrite and Ammonia in Organic Electrolyte Solutions During Nitrogen Reduction Experiments
Author(s) -
Hodgetts Rebecca Y.,
Du HoangLong,
MacFarlane Douglas R.,
Simonov Alexandr N.
Publication year - 2021
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202100251
Subject(s) - chemistry , acetonitrile , nitrite , electrolyte , inorganic chemistry , ammonia , nitrogen , redox , adsorption , catalysis , solvent , electrode , nitrate , organic chemistry
Oxidised nitrogen species (NO x ) are recognised as a major source of false‐positive nitrogen reduction reaction (NRR) results. Even when addressed, NO x are commonly eradicated at the initial stages of the experiment only. The present work demonstrates the shortcomings of this approach through a scrutiny of the evolution of NH 3 , NO 2 − and NO 3 − during the reduction of N 2 ‐saturated acetonitrile solutions with an Fe‐modified electrode. Notwithstanding, thorough purification of the experimental setup, persistent evolution of NO 2 − during electroreduction was detected in solution and attributed to the pH increase at the electrode surface inducing the release of strongly adsorbed adventitious nitrite. This species could be then reduced to NH 3 , while the rate of the NRR was unmeasurably low, as confirmed by 15 N 2 reduction experiments. This effect of the electrochemically induced changes in pH has not been previously discussed in nonaqueous NRR, which is arguably the only effective means for the N 2 electroreduction to NH 3 . This work also demonstrates that CH 3 CN might present a suitable solvent for the NRR if a genuinely active catalyst that operates at reasonable overpotentials becomes available.