Boosting Electrocatalytic Ammonia Synthesis via Synergistic Effect of Iron-Based Single Atoms and Clusters.

Xu, Li; Liu, Tong; Liu, Dong; Xu, Airong; Wang, Sicong; Huang, Hui; Liu, Xiaokang; Sun, Mei et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Electrocatalytic reduction of nitrate to ammonia (NO<sub>3</sub>RR) is gaining attention for low carbon emissions and environmental protection. However, low ammonia production rate and poor selectivity have remained major challenges in this multi-proton coupling process. Herein, we report a facile strategy toward a novel Fe-based hybrid structure composed of Fe single atoms and Fe<sub>3</sub>C atomic clusters that demonstrates outstanding performance for synergistic electrocatalytic NO<sub>3</sub>RR. By <i>operando</i> synchrotron Fourier transform infrared spectroscopy and theoretical computation, we clarify that Fe single atoms serve as the active site for NO<sub>3</sub>RR, while Fe<sub>3</sub>C clusters facilitate H<sub>2</sub>O dissociation to provide protons (*H) for continued hydrogenation reactions. As a result, the Fe-based electrocatalyst exhibits ammonia Faradaic efficiency of nearly 100%, with a corresponding production rate of 24768 μg h<sup>-1</sup> cm<sup>-2</sup> at -0.4 V vs RHE, exceeding most reported metal-based catalysts. This research provides valuable guidance toward multi-step reactions.