Mitigating Intraphase Catalytic-Domain Transfer via CO₂ Laser for Enhanced Nitrate-to-Ammonia Electroconversion and...

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 NH₄ ⁺ production rate of 10.9 mg h^-1 cm^-2 at -0.47 V versus Reversible Hydrogen Electrode 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, density functional theory 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 highlights the innovative use of CO₂ laser irradiation to transform Prussian blue analogs into cost-effective catalysts with hierarchical structures for NO₃RR-to-NH₃ conversion, positioning the Zn-NO₃ ^- battery as a promising technology for industrial applications.