Ammonia plays a vital role in agriculture and the development of next-generation carbon-free energy systems. As a supplementary or alternative to the Haber-Bosch process, renewable ammonia synthesis remains technologically pursued. Electrochemical nitrate reduction reaction (NO3−RR) to ammonia (NH3) represents a promising route for sustainable NH3 production and effective nitrogen recovery. However, sluggish kinetics and the competing hydrogen evolution reaction (HER) make the efficient production of NH3 still challenging. Developing high-performance catalysts and electrolyzers is therefore essential to improve electrochemical ammonia production and advancing its practical application.
Recently, a research team led by Prof. BAO Xinhe from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has made new progress in electrochemical ammonia synthesis. A CuPd bimetallic catalyst with abundant Cu-PdHx interfaces is synthesized, enabling efficient electrocatalytic nitrate-to-ammonia conversion. The interface-enhanced intrinsic activity provides a high production rate, long-term stability, and demonstrated scalability in membrane electrode assembly (MEA) electrolyzers.
This study was published in Nature Synthesis on November 19.
Copper–palladium hydride interfaces achieve efficient and stable nitrate electrolysis in a membrane electrode assembly electrolyzer (Image by Yunfan Fu and Shuo Wang)
The researchers developed a high-performance CuPd-Interface catalyst, which dynamically formed abundant Cu-PdHx interfacial sites with high intrinsic catalytic activity in situ under NO3−RR conditions. In an MEA electrolyzer, the CuPd-Interface achieved an NH3 production rate of 19.9 mmol h−1 cm−2 with a current density of 5 A cm–2 at a full-cell voltage of 2.56 V. The stability test operating at 2 A cm−2 with an NH3 Faradaic efficiency of ~86.8% was sustained over 1000 h.
In situ physicochemical characterizations and density functional theory (DFT) calculations revealed that the substantially enhanced performance is attributed to the superior intrinsic activity of the Cu-PdHx interfaces. The hydrogen redistribution induced by overflow at the Cu-PdHx interface effectively modulates the local electronic structure of the active sites, thereby optimizing the adsorption of NO3−, promoting the desorption of NH3 and enabling an energetically favorable pathway towards NH3 production.
Furthermore, the scale-up demonstration using an electrolyzer stack with five 100 cm2 MEAs achieved the highest NH3 production rate of 8.7 mol h–1 at 500 A and continuously produced NH3 at a rate of 1.6 mol h–1 at 100 A for 100 h, underscoring its industrial applicability.
This manuscript provides insight into the structure-activity relationship of CuPd bimetallic sites and suggests an effective approach to increase the intrinsic activity of bimetallic catalysts through in situ dynamic construction of beneficial interfaces, enabling efficient conversion of the pollutant NO3− to high value-added products.
The above work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences and the National Natural Science Foundation of China. (Text/Picture Yunfan Fu and Shuo Wang).
Article Link: https://www.nature.com/articles/s44160-025-00941-1