One-step synthesized Nb2O5−y-decorated spinel-type (Ni,V,Mn)3O4−x nanoflowers for boosting electrocatalytic reduction of nitrogen into ammonia

Two renewable methods for reducing greenhouse gas emissions associated with ammonia (NH3) production are the renewable H2-combined Haber–Bosch process and the electrochemical nitrogen reduction reaction (eNRR). However, progress in eNRR has fallen short of expectations. Here, we demonstrated a well-...

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Published in:Green chemistry : an international journal and green chemistry resource : GC 2023-12, Vol.25 (24), p.10498-10512
Main Authors: Tadele Negash Gemeda, Dong-Hau, Kuo, Quoc-Nam Ha
Format: Article
Language:English
Subjects:
Ammonia
Chemical reduction
Electrocatalysts
Electrochemistry
Electron transport
Emissions
Emissions control
Energy conversion
Energy efficiency
Green chemistry
Greenhouse gases
Haber Bosch process
Manganese
Metal foams
Nickel
Niobium oxides
Nitrogen
Performance evaluation
Quaternary systems
Spinel
Synthesis
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Summary:Two renewable methods for reducing greenhouse gas emissions associated with ammonia (NH3) production are the renewable H2-combined Haber–Bosch process and the electrochemical nitrogen reduction reaction (eNRR). However, progress in eNRR has fallen short of expectations. Here, we demonstrated a well-controlled electrochemically viable and clean NH3 production with spinel-type (V,Ni,Mn)3O4−x/Nb2O5−y nanoflowers, successfully synthesized via a facile one-pot hydrothermal method on nickel foam, aimed at boosting the eNRR performance, after surveying many Ni–V–Mn–Nb quaternary, ternary, and binary oxide systems for their electrochemical and structural properties. The best NH3 yield from a quaternary system exhibited the most promising results, achieving 3.19 mg h−1 cm−2 (1.28 mg h−1 mgcat.−1) at a potential of −0.5 V vs. RHE, with a remarkable faradaic efficiency (FE) of 22.7%, which is superb among the current state of the art methods. Besides, the electrocatalyst performance, evaluated in terms of energy conversion, showed a cell energy efficiency of 37.66%. An N≡N bond-weakening micro-mechanism of electron transport for the nonstoichiometric Ni–V–Mn–Nb oxide system is proposed to elucidate this exceptional activity. Furthermore, we suggest a reaction micro-mechanism encompassing electron transport and N2 trapping, contributing to the observed excellent activity in NH3 production.
ISSN:1463-9262
1463-9270
DOI:10.1039/d3gc03831a