Abstract

The electrochemical reduction of nitrate (eNO₃RR) to ammonia (NH₃) is an efficient method for mitigating nitrate (NO₃⁻) pollutant while offering sustainable NH₃ generation under ambient environments. However, optimizing NO₃⁻ adsorption on catalytic surfaces and promoting adsorbed hydrogen formation remain challenging. Herein, we introduce pulsed laser irradiation in liquid for the first time to design a metal–metal–ligand-coordinated CoCu heterodimer catalyst with a pseudo-D_3h symmetry anchored on nitrogen-doped graphene oxide (CoCu-HeD/NGO), enabling a tandem catalytic effect for the eNO₃RR. The catalyst reaches a remarkable Faradaic efficiency of 91% at −0.4 V vs. RHE and a high NH₃ production rate of 25 mg h⁻¹ cm⁻² at −0.5 V vs. RHE. Combined theoretical and in situ spectroelectrochemical analyses reveal that the synergistic interaction among Co and Cu dual sites enhances NO₃⁻ adsorption, weakens N–O bonds, and facilitates the establishment of Langmuir–Hinshelwood-type hydrogenation intermediates, steering the tandem reaction pathway toward selective NH₃ formation. Furthermore, a Zn–nitrate battery with a CoCu-HeD/NGO cathode integrates energy generation and NH₃ synthesis with environmental remediation, delivering 5.26 mW cm⁻² power density and stable discharge performance. Practical NH₃ production is verified via Ar stripping–acid-trapping methods. This work establishes a new paradigm for the rational design of site-selective electrocatalysts for hybrid energy-to-chemical platforms.