The tensile strain promotes NITRR (Figures 2a,b). At any potentials from 0.0 to -1.0 V versus RHE, FENH3, JNH3, and vNH3 all followed the trend of Ru-ST-12 > Ru-ST-5 > Ru-ST-0.6 implying a strain-dependent performance. JNH3 values (recorded at -0.8 V versus RHE) of Ru-ST-12 and Ru-ST-5 were improved to be 77 and 14 times that of Ru-ST-0.6, respectively. We compared vNH3 of the three samples with that of Ru nanoclusters possessing 7.9 at.% oxygen dopants and 6.5% strain. vNH3 plotted as a function of oxygen dopant concentration follows a volcano-shaped trend rather than linear (Figure S16) and excludes the dominant role of dopant-mediated ligand effects in our NITRR.