Mitigating Intraphase Catalytic‐Domain Transfer via CO₂ Laser for Enhanced Nitrate‐to‐Ammonia Electroconversion and Zn‐Nitrate Battery Behavior

Abstract

Developing sustainable energy solutions is critical for addressing the dual challenges of energy demand and environmental impact. In this study, a zinc‐nitrate (Zn‐NO3−) battery system was designed for the simultaneous production of ammonia (NH3) via the electrocatalytic NO3− reduction reaction (NO3RR) and electricity generation. Continuous wave CO2 laser irradiation yielded precisely controlled CoFe2O4@nitrogen‐doped carbon (CoFe2O4@NC) hollow nanocubes from CoFe Prussian blue analogs (CoFe‐PBA) as the integral electrocatalyst for NO3RR in 1.0‐M KOH, achieving a remarkable NH3 production rate of 10.9 mgh−1cm−2 at −0.47 V versus RHE with exceptional stability. In‐situ and ex‐situ methods revealed that the CoFe2O4@NC surface transformed into high‐valent Fe/CoOOH active‐species, optimizing the adsorption energy of NO3RR (*NO2 and *NO species) intermediates. Furthermore, DFT calculations validated the possible NO3RR pathway on CoFe2O4@NC starting with NO3− conversion to *NO2 intermediates, followed by reduction to *NO. Subsequent protonation forms the *NH and *NH2 species, leading to NH3 formation via final protonation. The Zn‐NO3− battery utilizing the CoFe2O4@NC cathode exhibits dual functionality by generating electricity with a stable open‐circuit voltage of 1.38‐V versus Zn/Zn2+ and producing NH3. This study inspires the simple design of low‐cost catalysts for NO3RR‐to‐NH3 conversion and positions the Zn‐NO3− battery as a promising technology for industrial applications.