Tandem catalytic sites of CuCo decorated carbon for high-efficiency nitrate electroreduction to ammonia and Zn-nitrate battery

The electrocatalytic nitrate reduction to ammonia (eNO 3 RR) offers a sustainable route to simultaneously decarbonize ammonia production and remediate nitrate wastewater. However, its efficiency is challenged by a complex multi-step reaction pathway; to address this, we designed a tandem copper‑cobalt catalyst supported on a carbon/nitrogen/oxygen substrate (CuCo-CNO). The carbon substrate not only provides stable anchoring sites for active metals but also facilitates strong electronic coupling between the tandem Cu and Co sites, thereby significantly enhancing catalytic activity and selectively promoting the critical eNO 3 RR steps. The CuCo-CNO catalyst achieves a high Faradaic efficiency of 96.5% and an ammonia selectivity of 95% at −0.8  V vs. RHE, significantly outperforming its single-metal counterparts (Cu-CNO and Co-CNO). In situ electrochemical-Raman spectroscopy reveals that the initially metallic Cu Co sites undergo electrochemically driven reconstruction into Cu 2 O and CoOOH. Compared with the single-metal analogs, theoretical calculations further indicate that CuCo-CNO exhibits a higher energy barrier for H 2 evolution and a lower eNO 3 RR energy barrier, confirming the synergistic catalytic mechanism. A Zn-NO 3 − battery assembled with CuCo-CNO as the cathode delivers a maximum power density of approximately 3.35 mW cm −2 . This work offers a valuable strategy for designing tandem catalysts on carbon supports for efficient electrocatalytic nitrate-to-ammonia conversion. Download: Download high-res image (130KB) Download: Download full-size image