Insights into boosting catalytic hydrogen evolution over Co doping Ru nanoparticles

•The significant lattice strain is induced by the incorporation of Co atoms into Ru matrix.•An excellent TOF of 443.7 min−1 was obtained over Ru0.6Co0.4/P25 during NH3BH3 hydrolysis.•The electron transfer from Co to Ru adjusts the electron density and the bonding strength of Ru-H.•The ensemble effect on optimized surface state leads to a bimolecular activation of H2O on Co atoms and AB on Ru atoms.