Highly ordered and surfactant-free PtxRuy bimetallic nanocomposites synthesized by electrostatic self assembly for methanol oxidation reaction

•Positively charged Ru (1.0nm, +6.6mV) and negatively charged Pt nanoparticles (2.2nm, −4.2mV) are synthesized by a surfactant-free manner.•Highly ordered PtxRuy nanocomposites are electrostatically self-assembled upon mixing.•CO oxidation and MOR activities of the PtxRuy/C are highly dependent on Pt/Ru ratio and all demonstrate enhanced activity.