Hierarchical Electronic Structure Modulation of Cu-Co Dual-Site and CNT Tandem Interface Enables Highly Efficient...

Electrocatalytic reduction of nitrate to ammonia (NO₃RR) is a highly efficient dual strategy that can both reduce NO₃ ^- pollution and achieve sustainable NH₃ production. To overcome the low efficiency bottleneck under neutral electrolyte conditions, this study designed a tandem catalyst Cu-Co-O/CNT-2 based on carbon nanotubes (CNT). By anchoring the Cu-Co dual sites on the CNT support, the electronic structure and reaction pathway were optimized. At -0.9 V vs RHE, the Cu-Co-O/CNT-2 catalyst exhibited an ammonia yield of 5.088 mg h^-1 cm^-2 and a Faradaic efficiency of 81.83%, significantly improving the NO₃RR performance. In situ FTIR characterization revealed the dominant NHO pathway and successfully captured the ^*NH₂OH intermediate. DFT calculations and in situ EPR analysis further indicate that the Cu-Co-O active sites preferentially adsorb ^*NO_x, while CNT effectively lowers the reaction energy barrier and enhances the multi-electron conversion efficiency by promoting the upward shift of the d-band center (-1.837 eV), thus driving the deoxygenation and stepwise hydrogenation of NO₃ ^- to NH₃. In summary, this study provides theoretical support for the design of efficient tandem catalytic systems and offers new insights into ammonia generation and resource conversion in the NO₃RR reaction.