In addition, digestion of silica from nano-Ru/nano-SiO2 in the presence of Ni powder can be employed to disassemble large Ru agglomerates on SiO2 into smaller Ru nanoparticles on the Ni surface with an oxide passivation layer. The synthesized oxide passivated Ni-supported Ru nanoparticles, in which unalloyed bimetallic nano-Ru and Ni are formed, are highly active and stable in low-temperature CO2 methanation .