Strain engineering has emerged as a promising strategy for tuning heterogeneous catalyst performance, yet its specific 

influence on ammonia synthesis over ruthenium remains unclear due to concurrent support-induced effects. Here, density 

functional theory calculations combined with mean-field microkinetic modeling are used to examine the impact of±5% 

biaxial strain on terrace Ru(0001) and stepped Ru(1010) surfaces. Tensile strain strengthens adsorption while compressive 

strain weakens it, with these trends governed by systematic shifts in d-band width. Because the stepped surface relaxes 

more readily, strain produces smaller energetic changes on Ru(1010) than on Ru(0001). Activation barriers follow Brønsted–Evans–Polanyi

relationships: tensile strain lowers the barriers for N₂ and H₂ dissociation but raises those for NHx

hydrogenation. Microkinetic analysis shows that N₂ dissociation remains rate limiting on Ru(0001), whereas the RDS on 

Ru(1010) varies between NH₂ hydrogenation and N₂ dissociation depending on reaction conditions, leading to opposite 

TOF responses to strain across the two facets. When combined to represent a realistic 2–4 nm Ru nanoparticle, overall 

activity follows the order pristine>tensile>compressive, indicating that unstrained surfaces yield the highest ammonia 

production. These results clarify how strain modifies reaction energetics and kinetics on Ru catalysts and provide a quantitative

basis for evaluating strain engineering in ammonia synthesis.