Electronic structure engineering of dual-atom catalysts to regulate N₂ adsorption geometry for enhanced nitrogen...

Understanding how electronic structure regulates N₂ adsorption geometry is crucial for establishing structure-activity relationships in the nitrogen reduction reaction (NRR), yet the intrinsic relationship between electronic structure modulation and adsorption geometry remains poorly understood. Herein, density functional theory calculations are employed to investigate the NRR on graphdiyne-supported Mo-TM dual-atom catalysts (Mo-TM@GDY, TM = 3d, 4d, and 5d transition metals). We demonstrate that the electronic structure of the secondary metal center drives a continuous transition of N₂ adsorption geometry from side-on to end-on configurations across the Mo-TM@GDY series, accompanied by charge transfer to adsorbed N₂ ranging from 0.19 to 0.97e. This adsorption geometry transition governs N₂ activation and reaction energetics, leading to distinct NRR pathways in which side-on adsorption promotes synergistic dual-metal activation of the NN bond, whereas end-on adsorption favors localized metal-N₂ interactions and shifts the potential-determining step to the initial N₂ activation process. Furthermore, volcano-type relationships between the limiting potential and both the ICOHP-derived N₂-DAC interaction strength and charge transfer to adsorbed N₂ establish a quantitative structure-activity framework linking electronic structure with catalytic performance. Six Mo-TM@GDY (TM = Cr, Fe, Y, Hf, Ta, and Re) catalysts exhibit promising NRR activity, selectivity, and stability, with Mo-Cr@GDY delivering the highest activity at a limiting potential of -0.34 V. This work establishes a structure-activity framework linking electronic structure, N₂ adsorption geometry, and catalytic performance, providing design principles for high-performance NRR electrocatalysts.