Noble and Non-Noble Metal Based Catalysts for Electrochemical Nitrate Reduction to Ammonia: Activity, Selectivity and Stability

Abstract

Excessive nitrate (NO₃⁻) contamination has emerged as a critical environmental issue owing to the widespread use of nitrogen-based fertilizers, fossil fuel combustion, and the discharge of industrial and domestic effluents. Consequently, electrochemical nitrate reduction (eNO₃R) to ammonia (NH₃) has emerged as a promising alternative to the traditional Haber-Bosch process. However, the industrial implementation of eNO₃R is hindered by low catalytic activity, poor selectivity, and limited stability owing to competing hydrogen evolution reactions. This paper provides a comprehensive overview of recent advancements in eNO₃R, particularly evaluating the catalytic activity, selectivity, and stability of both noble and non-noble metal catalysts. This review elucidates innovative catalyst design strategies, state-of-the-art developments, and potential directions for future research. Additionally, the paper explores the fundamental mechanisms underlying eNO₃R for NH₃ production, including electrocatalyst development methodologies, electrolyte effects, in situ characterization techniques, theoretical modeling, and cell design considerations. Moreover, factors influencing NH₃ selectivity and catalyst structural composition are thoroughly examined. Finally, this review provides comprehensive insights into optimizing eNO₃R processes for synthesizing NH₃, which can promote further advancements in this field.

Graphical Abstract

Keywords

Nitrate reduction / Electrocatalysis / NH₃ production / Activity / Selectivity / Stability

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Funding

Key Technologies Research and Development Program(2022YFE0138900)

National Natural Science Foundation of China(91645110)

Science and Technology Innovation Plan Of Shanghai Science and Technology Commission(19JC1410500)

Fundamental Research Funds for the Central Universities(2232022D-18)

Shanghai Sailing Program(22YF1400700)

RIGHTS & PERMISSIONS

Shanghai University and Periodicals Agency of Shanghai University