High-performance CuCo aerogel electrocatalyst for relay electroreduction of nitrate to ammonia

Abstract

Renewable energy-driven electroreduction of nitrate to ammonia presents a low-carbon and promising route for sustainable ammonia synthesis. For Cu-based electrocatalysts, due to their sluggish kinetics of the hydrogenation steps, nitrite often accumulates on the electrocatalysts surface, resulting in low ammonia yield rate and selectivity, as well as serious deactivation of electrocatalysts. Herein, a continuous relay site construction strategy that integrates the Cu─Co relay sites into an interconnected porous network is proposed. Owing to the adequately exposed interconnected Cu─Co relay sites, regulated adsorption energy of the nitrate and intermediates, promoted hydrogenation ability, and excellent self-supportability of 3D skeleton, the Cu₅₀Co₅₀ aerogel realizes the high-efficiency relay catalysis with an ultrahigh NH₃ yield rate of 3.3 ± 0.27 mmol·h⁻¹·cm⁻² (2110 ± 173 mmol·h⁻¹·gcat⁻¹) and a large NH₃ Faraday efficiency of ≈100% at −0.2 V vs. RHE. The potential need for the Cu₅₀Co₅₀ aerogel in the electrocatalysis at an industrial-level current density remains stable even after 100-h chronopotentiometry measurement, demonstrating excellent long-term stability. Besides, the large-scale preparation (>1 g) of the Cu₅₀Co₅₀ aerogel can be easily achieved, and its exceptional performance is maintained consistently. Such a continuous relay site construction strategy opens a new way for developing advanced electrocatalysts for high-efficiency relay catalysis.