CO₂ Laser‐Stabilized Ni‐Co Dual Single‐Atomic Sites for Energy Generation and Ammonia Harvesting

Abstract

AbstractDual single‐atom catalysts (DSACs) hold immense potential in electrochemical nitrate (NO3−) reduction (EcNR) as a sustainable replacement to the Haber–Bosch process for the production of ammonia (NH3). However, challenges such as synthesis complexity, low purity, scalability, and stability have hindered their practical application. Herein, a rapid and scalable method is introduced to stabilize low‐cost 3d transition metals (Ni and Co) as DSACs on Ti3C2Tx MXene in 10 min using continuous‐wave CO2‐laser irradiation. Ni2+ and Co2+ ions are chelated and stabilized as single atoms onto an L‐tryptophan‐modified Ti3C2Tx surface via metal─O and metal─N bonds, forming Ni‐single atom catalyst (SAC)/MXene, Co‐SAC/MXene, and NiCo‐DSAC/MXene. This approach enhances MXene properties, enabling the synthesis of efficient atomic‐level electrocatalysts. Potential‐resolved in situ Raman spectroelectrochemistry and density functional theory reveal that EcNR proceeds through NO3− reduction to *NO2, *NO, *NH, and *NH2 intermediates, ultimately forming NH3 via final protonation step. This process exhibits a low limiting potential of −0.37 V, with *NO2 protonation identified as the critical step. NiCo‐DSAC/MXene exhibited superior EcNR performance for NH3 production in 1.0 M potassium hydroxide with sustained multiple cyclic stability. Furthermore, this catalyst is integrated into a Zn–NO3− a battery that simultaneously removes NO3−, generates energy, and synthesizes NH3.