Abstract
Previous theoretical work has predicted vanadium and niobium nitrides to be catalytically active toward the electrochemical reduction of dinitrogen to ammonia and inactive for the hydrogen evolution reaction. The present experimental study investigates the electrocatalytic activity of vanadium(III) nitride, niobium(III) nitride, and Nb 4 N 5 for the nitrogen reduction reaction in aqueous electrolyte solutions of different pH under ambient conditions using a robust testing protocol and thoroughly controlled experimental conditions to exclude any contamination with adventitious sources of ammonia and nitrogen oxides. VN and Nb 4 N 5 (supported on carbon cloth) were synthesized by annealing of hydrothermally produced hydroxide precursors in an NH 3 atmosphere at 600-1100 °C; NbN was obtained by a solid-state reaction between niobium(V) chloride and urea at 1000 °C. Comprehensive testing of the materials under a wide range of conditions unambiguously demonstrates their inability to catalyze the electrosynthesis of ammonia from dinitrogen, as well as the propensity of VN (synthesized at 600 °C) and Nb 4 N 5 to release lattice nitride in a noncatalytic process, which leads to the formation of ammonia under reductive conditions. Thus, polycrystalline nitrides of vanadium and niobium are concluded to be catalytically inactive toward the ammonia electrosynthesis from N 2 dissolved in water. The present work additionally emphasizes the compulsory requirement for the implementation of reliable testing and analysis procedures for the assessment of the catalytic properties of materials for the nitrogen reduction reaction.
| Original language | English |
|---|---|
| Pages (from-to) | 6839−6850 |
| Number of pages | 12 |
| Journal | ACS Sustainable Chemistry and Engineering |
| Volume | 7 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Jan 2019 |
Keywords
- Aqueous
- Dissolved nitrogen
- Mars-van Krevelen mechanism
- Nitrogen reduction reaction
- pH effect
Cite this
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Critical Assessment of the Electrocatalytic Activity of Vanadium and Niobium Nitrides toward Dinitrogen Reduction to Ammonia. / Du, Hoang Long; Gengenbach, Thomas R.; Hodgetts, Rebecca; Macfarlane, Douglas R.; Simonov, Alexandr N.
In: ACS Sustainable Chemistry and Engineering, Vol. 7, No. 1, 01.01.2019, p. 6839−6850.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Critical Assessment of the Electrocatalytic Activity of Vanadium and Niobium Nitrides toward Dinitrogen Reduction to Ammonia
AU - Du, Hoang Long
AU - Gengenbach, Thomas R.
AU - Hodgetts, Rebecca
AU - Macfarlane, Douglas R.
AU - Simonov, Alexandr N.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Previous theoretical work has predicted vanadium and niobium nitrides to be catalytically active toward the electrochemical reduction of dinitrogen to ammonia and inactive for the hydrogen evolution reaction. The present experimental study investigates the electrocatalytic activity of vanadium(III) nitride, niobium(III) nitride, and Nb 4 N 5 for the nitrogen reduction reaction in aqueous electrolyte solutions of different pH under ambient conditions using a robust testing protocol and thoroughly controlled experimental conditions to exclude any contamination with adventitious sources of ammonia and nitrogen oxides. VN and Nb 4 N 5 (supported on carbon cloth) were synthesized by annealing of hydrothermally produced hydroxide precursors in an NH 3 atmosphere at 600-1100 °C; NbN was obtained by a solid-state reaction between niobium(V) chloride and urea at 1000 °C. Comprehensive testing of the materials under a wide range of conditions unambiguously demonstrates their inability to catalyze the electrosynthesis of ammonia from dinitrogen, as well as the propensity of VN (synthesized at 600 °C) and Nb 4 N 5 to release lattice nitride in a noncatalytic process, which leads to the formation of ammonia under reductive conditions. Thus, polycrystalline nitrides of vanadium and niobium are concluded to be catalytically inactive toward the ammonia electrosynthesis from N 2 dissolved in water. The present work additionally emphasizes the compulsory requirement for the implementation of reliable testing and analysis procedures for the assessment of the catalytic properties of materials for the nitrogen reduction reaction.
AB - Previous theoretical work has predicted vanadium and niobium nitrides to be catalytically active toward the electrochemical reduction of dinitrogen to ammonia and inactive for the hydrogen evolution reaction. The present experimental study investigates the electrocatalytic activity of vanadium(III) nitride, niobium(III) nitride, and Nb 4 N 5 for the nitrogen reduction reaction in aqueous electrolyte solutions of different pH under ambient conditions using a robust testing protocol and thoroughly controlled experimental conditions to exclude any contamination with adventitious sources of ammonia and nitrogen oxides. VN and Nb 4 N 5 (supported on carbon cloth) were synthesized by annealing of hydrothermally produced hydroxide precursors in an NH 3 atmosphere at 600-1100 °C; NbN was obtained by a solid-state reaction between niobium(V) chloride and urea at 1000 °C. Comprehensive testing of the materials under a wide range of conditions unambiguously demonstrates their inability to catalyze the electrosynthesis of ammonia from dinitrogen, as well as the propensity of VN (synthesized at 600 °C) and Nb 4 N 5 to release lattice nitride in a noncatalytic process, which leads to the formation of ammonia under reductive conditions. Thus, polycrystalline nitrides of vanadium and niobium are concluded to be catalytically inactive toward the ammonia electrosynthesis from N 2 dissolved in water. The present work additionally emphasizes the compulsory requirement for the implementation of reliable testing and analysis procedures for the assessment of the catalytic properties of materials for the nitrogen reduction reaction.
KW - Aqueous
KW - Dissolved nitrogen
KW - Mars-van Krevelen mechanism
KW - Nitrogen reduction reaction
KW - pH effect
UR - http://www.scopus.com/inward/record.url?scp=85062853311&partnerID=8YFLogxK
U2 - 10.1021/acssuschemeng.8b06163
DO - 10.1021/acssuschemeng.8b06163
M3 - Article
VL - 7
SP - 6839−6850
JO - ACS Sustainable Chemistry & Engineering
JF - ACS Sustainable Chemistry & Engineering
SN - 2168-0485
IS - 1
ER -