Modified polyol method for a highly alloyed PtRu/C electrocatalyst: Effect of hot injection of metal precursor and NaOH

In this study, two modified polyol methods (I and II) were proposed to improve the alloying degree of PtRu nanoparticles. A 20 wt% PtRu/C catalyst was successfully synthesized using modified polyol method I, in which a metal precursor-ethylene glycol (EG) solution was injected into a hot NaOH-EG solution. The alloying degree of PtRu/C reached 56% with modified polyol method I. In modified polyol method II, the metal precursor- and NaOH-EG solutions were simultaneously injected into a hot EG solution, and an alloying degree of 84% was achieved by preventing the original precursor salt from becoming a metal hydroxide under high pH. The catalysts prepared by each modified method were characterized using XRD, HR-TEM, cyclic voltammetry, CO stripping, and chronoamperometry. The results showed that the catalysts prepared by the modified polyol methods had highly alloyed surfaces that exhibited strong CO tolerance and enhanced activity. The electrochemical activities of the developed catalysts for methanol oxidation were higher than that of commercial PtRu/C in terms of the mass-normalized current density.