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Nitrate pollution control and resource utilization is an important pathway toward water remediation and green ammonia synthesis. However, under industrial current densities (A cm-2), complex multi-electron/multi-proton transfer steps and sluggish hydrogenation kinetics severely limit practical applications. To address this challenge, Prof. Dong Lin’s team systematically investigated the differences between the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms in nitrate electroreduction from a microscopic reaction pathway perspective.
It was found that in monometallic Co catalytic systems, the reaction mainly follows an E-R pathway, where hydrogenation involving solvated protons is limited, leading to low surface hydrogen coverage, sluggish kinetics, and restricted Faradaic efficiency. By introducing Ru to construct a RuCo bimetallic system, water dissociation capability is significantly enhanced and surface adsorbed hydrogen (*H) concentration is increased, thereby driving the mechanism transition from E-R to L-H, enabling efficient hydrogen atom transfer (HAT) involving adsorbed hydrogen. This mechanistic transition leads to remarkable performance enhancement: the RuCo catalyst achieves an ammonia production rate of 135.53 ± 1.18 mg h-1 cm-2 with nearly 100% Faradaic efficiency, while maintaining stable operation for over 1000 hours at 1 A cm-2, demonstrating strong industrial application potential. Microkinetic simulations and in situ spectroscopic results further confirm that an optimal *H coverage (~0.45) is the key to enabling the efficient L-H pathway. This work not only deepens the understanding of hydrogenation mechanisms in nitrate electroreduction, but also provides new theoretical guidance for the design of efficient electrocatalysts, offering significant implications for electrochemical ammonia synthesis and nitrogen-containing pollutant valorization.
Figure 1 Schematic illustration of different hydrogenation mechanisms in nitrate electroreduction.
The study entitled "Langmuir-Hinshelwood pathway enables 1000-h stable nitrate-to-ammonia electroreduction at 1 A cm-2" was published in Nature Communications (DOI: https://doi.org/10.1038/s41467-026-74321-4). This work was led by PhD candidate Tang Yu as the first author. Associate Professor Zou Weixin and Professor Yan Shicheng (School of Modern Engineering and Applied Sciences) served as corresponding authors. Professor Dong Lin, Master’s students Li Jiale and Li Yanfang, together with PhD candidate Ran Pan contributed as co-authors. This research was supported by the National Natural Science Foundation of China (Grant Nos. 62375120, 52272217, 51872135, 51572121, and 21633004), the Natural Science Foundation of Jiangsu Province (No. BK20240171), the Fundamental Research Funds for the Central Universities (No. 2026300350), and the Jiangsu Science and Technology Innovation Program for Carbon Peaking and Carbon Neutrality (No. BE2022028-1). The authors gratefully acknowledge Dr. Zhang Xincheng from Zhejiang University for his leading contribution to the techno-economic analysis in this work.
