Research advancements in self-supporting electrodes for the electrocatalytic reduction of nitrate to ammonia

As a crucial chemical feedstock and potential green energy carrier, the development of sustainable ammonia synthesis pathways has garnered significant attention. The electrocatalytic nitrate reduction synthesis of ammonia technology not only converts water pollutants into high-value ammonia products but also enables mild synthesis under ambient temperature and pressure conditions, offering potential to replace the traditional energy-intensive Haber-Bosch process. Although the intrinsic activity of the catalyst is the key factor for performance of the electrocatalytic nitrate reduction, effectively integrating it into the working electrode is the final step towards achieving efficient energy conversion. Self-supporting electrodes, an integrated electrode where the active material is directly constructed on the conductive skeleton, eradicate the negative impacts brought by binders and enhance the charge transfer rate, and mass transfer efficiency from a structural level by constructing a robust conductive network and open mass transfer channels. This paper systematically reviews the latest research progress of self-supporting electrodes in electroreduction of nitrate to synthesis ammonia, focusing on the structural characteristics and performance of metal-based and carbon-based material systems. It thoroughly analyzes the advantages and applicability of preparation methods such as electrochemical deposition, hydrothermal/solvothermal processes, and high-temperature pyrolysis. Additionally, the paper summarizes explorations of self-supporting electrodes in reactor design, system integration, and practical wastewater treatment applications, while outlining challenges in achieving activity-selectivity balance, long-term stability, and cost control. Finally, it proposes future research directions including multi-scale structural design, in-situ characterization technology applications, and deep integration with renewable energy systems, providing theoretical references and technical pathways to advance this technology from laboratory to practical implementation.