Palladium-based nanocatalysts for NH₃ synthesis through nitrate electroreduction: nanocomposites, alloys, and atomically precise nanoclusters

The electrochemical nitrate reduction reaction (NO3RR) to produce NH(3 )has become a sustainable route for contaminant removal and producing value-added chemical and/or green energy carriers simultaneously. Pd-based nanocatalysts have been attracting increasing attention thanks to their high activity, excellent stability, and potential practical applications. This review first introduces the fundamentals of the NO3RR and explains the unique advantages of using Pd-based nanocatalysts for the NO3RR. Then, it summarizes the recent progress regarding nitrate electroreduction catalyzed by Pd-based nanocatalysts, including Pd nanomaterials, Pd-based composites, Pd alloys, and atomically precise Pd-based nanoclusters. Finally, the major challenges and future perspectives are proposed.