Low-Ru-Content CuCoRu Aerogel for Boosted Electrocatalytic Nitrate Reduction to Ammonia

Abstract

Electrocatalytic nitrate reduction to ammonia (eNRA) offers a sustainable and green pathway for ammonia (NH₃) synthesis. Although due to the inferior hydrogenation ability, Cu-based nonprecious electrocatalysts often suffer a low NH₃ Faradaic efficiency and high overpotential are often needed to deep reduction of *NO₂, resulting in a high energy consumption. Herein, a galvanic replacement strategy is proposed to synthesize a CuCoRu Aerogel (CuCoRu AG) electrocatalyst with low-content Ru (10.7 at%) to realize efficient eNRA at a significantly reduced overpotential. The optimized Cu₅Co₅Ru AG displays a remarkable NH₃ yield rate of 2.7 ± 0.1 mmol cm⁻² h⁻¹ with an ultrahigh Faradaic efficiency of 97.0 ± 3.81% at −0.1 V versus RHE, surpassing most reported Cu-based electrocatalysts. Systematic characterizations and theoretical calculations indicate that the rational incorporation of low amounts of Ru can further regulate the electronic state to significantly reduce the hydrogenation barrier. Furthermore, the robust Aerogel network architecture provides a good self-supportability to avoid excess agglomeration and ripening, endowing a long-term operational durability over 100 h of continuous electrolysis. This work underscores the pivotal role of electronic structure regulation and three-dimensional porous architectures in the design of next-generation, low-cost, and high-efficiency eNRA electrocatalysts.

Keywords

Aerogel / electrocatalysis / electrocatalytic nitrate reduction to ammonia

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