In this study, the Ru0.04Ni0.96/C(T) catalysts were successfully prepared by the simple methods of hydrazine -reduction and galvanic replacement, where 0.04/0.96 and T represented the Ru/Ni atomic ratio and reducing temperature of the catalyst in N-2+10%H-2, respectively. The nanostructures of the Ru0.04Ni0.96 nanoparticles in the Ru(0.04)Nio(0.96)/C(T) catalysts were controlled by modulating their annealing temperature in N-2+10%H-2 and characterized by an array of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy energy dispersive X-ray spectroscopy (STEM-EDS) mapping and high -sensitivity low -energy ion scattering (HS -LEIS). The Ru0.04Ni0.96/C(30) catalyst, which was composed of Ru clusters or single atoms supported on Nil Ni(OH)(2) nanoparticles, exhibited much better catalytic performance for benzene hydrogenation than the Ru0.04Ni0.96/C(T) catalysts reduced at above 30 degrees C, such as RU(0.04)Nio(0.96)/C(160) with the nanostructure of partial Ru0.04Ni0.9 alloy and Ru0.04Ni0.96/C(280) with the nanostructure of complete Ru0,04Ni0.9 alloy. The reason was that the synergistic effect of multiple active sites Ru, Ni and Ni(OH)(2) sites was present in the Ru(0.04)Nio(0.96)/C(30) catalyst, where hydrogen was preferentially activated at Ru sites, benzene was probably activated at Ni(OH)2 surface and Ni acted as a "bridge" for transferring activated H* species to activated benzene by hydrogen spillover effect, hydrogenating and forming product cyclohexane. This study also provided a typical example to illustrate that the synergy effect of multiple active sites can largely improve the catalytic hydrogenation performance. (C) 2017 Elsevier B.V. All rights reserved.