A Composition-Precise Synthesis of Porous PtCo Alloy Catalysts Mediated by Aerosol-Microdroplet Confinement.

This work reports a composition-precise synthesis of porous PtCo-alloy catalysts mediated by aerosol-microdroplet confinement, which begins with the complete conversion of inorganic salts into Pt-Co-PVP composite precursor, followed by calcination and reduction to yield a carbon-supported PtCo alloy. A series of composition-controlled PtCo/C alloy catalysts is synthesized. In situ XRD analysis provided clear evidence of the structural transformation from the Pt-Co-PVP composite to the PtCo alloy during calcination under a H2/Ar atmosphere. The process began at 300 °C with the concurrent formation of two distinct populations of alloy nanoparticles with high and low Pt/Co ratios. With increasing temperature, the high-ratio nanoparticles are gradually converted into those with a lower ratio. The Pt/Co ratios in these catalysts demonstrated a remarkable consistency with the predetermined ratios in the mother solution. The Co/Pt mass ratio can span a wide range from 0 to 150%. As for a case application for electrocatalytic methanol oxidation reaction, the optimized Pt1Co0.8/C alloy catalyst achieved a mass activity of 1.8 A/mg(Pt), which is 2.4 times that of a commercial PtCo/C-TKK catalyst, 2.2 and 4.4 times that of Pt1Co0.8/C-Im and Pt/C-Im catalysts prepared via impregnation. The aerosol-microdroplet confinement strategy also enables the composition-precise synthesis of other alloy catalysts.