Integrated NH 3 Synthesis and Energy Output via a Microstructure‐Engineered CoRu/Pd/PCNFs Tandem Catalyst in a Zn─NO 3 − Battery

ABSTRACT The electrocatalytic nitrate reduction reaction (NO 3 RR) to ammonia (NH 3 ) is vital for sustainable nitrogen management but is often hindered by mass transport limitations and the competing hydrogen evolution reaction (HER). Herein, we report a rationally designed tandem CoRu/Pd nanoparticles supported on porous carbon nanofibers (CoRu/Pd/PCNFs), derived from a ZIF‐8 and PAN precursor. This hierarchically porous architecture enhances the mass transport, enabling tandem catalysis via synergistic metal active sites. The CoRu/Pd/PCNFs catalyst achieves an exceptional NH 3 Faradaic efficiency (FE NH3 ) of 98.69% and a high yield rate of 78.00 µmol h −1 mg cat −1 at −0.6 V (vs. RHE). Furthermore, when configured in a Zn─NO 3 − battery, at a discharge current density of 6 mA mg −1 , it enables simultaneous ammonia production and power generation, delivering a FE NH3 of 91.11% and NH 3 yield rate of 25.28 µmol h −1 mg cat −1 . In situ characterization suggests the tandem structure precisely directs surface‐adsorbed hydrogen (*H) toward nitrogen‐containing intermediates by strengthening *H adsorption and enrichment. This mechanism significantly boosts NH 3 selectivity while effectively suppressing the HER. This work highlights the potential of combining microstructure engineering with precise active site design to manage key reactive species in complex electrocatalytic energy systems.