Atomic Precision CoCu Heterodimers with Pseudo-D3h Symmetry Enable Tandem Nitrate Reduction

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-D3h 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 & horbar;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.