Atomically Dispersed Cu-Pd Dual Sites on Nitrogen-Doped Carbon for Efficient Electroreduction of Nitrite to Ammonia

Abstract

Electrocatalytic conversion of aqueous nitrite to ammonia offers a sustainable route that unites water remediation with emerging energy carriers. Yet, conventional catalysts often suffer from both the competing hydrogen evolution reaction (HER) and sluggish hydrogenation kinetics of key intermediates. Here, we synthesized an atomically dispersed Cu-Pd dual-site catalyst anchored on N-doped carbon (Cu-Pd-N-C) by high-temperature pyrolysis. In alkaline media, the catalyst delivered outstanding nitrite-to-ammonia performance: at -0.6 V vs. RHE, the NH3 yield rate reached 9.7 mg h-1 cm-2; across -0.3 to -0.7 V vs. RHE, the peak Faradaic efficiency exceeded 95%, surpassing Cu-N-C and representative state-of-the-art counterparts. Electrochemical analyses revealed that Pd incorporation drives electronic redistribution between Cu and Pd, rendering Cu centers electron-deficient to enhance nitrite adsorption and activation, while the strong Pd-H interaction favors the accumulation of interfacial adsorbed hydrogen. This dual-site synergy suppressed HER and sustained the stepwise hydrogenation-deoxygenation of nitrogen-containing intermediates, thereby affording high selectivity and activity for the nitrite reduction reaction. The findings establish an atomically precise site-engineering strategy for high-performance electrocatalysts and provide a relevant reference for the green treatment of nitrite-bearing wastewater.