Facile synthesis of a molybdenum phosphide (MoP) nanocomposite Pt support for high performance methanol oxidation

Abstract

Metal phosphides are of great recent interest as promoters to precious metal-driven catalytic oxidation of alcohols in direct alcohol fuel cells. In this work, a novel approach for facile and environmentally friendly synthesis of molybdenum phosphide (MoP) nanocrystals anchored on graphitized carbon is developed by one-step pyrolysis of a phosphorus-containing resin exchanged with Mo⁵⁺. A significant promotion effect of MoP on Pt in methanol electrooxidation is observed. The Pt–MoP/C catalyst exhibits ultrahigh electroactivity, and compared to commercial Pt/C, this catalyst reaches a −140 mV more negative onset potential and has 10 times the mass activity at 0.4 V vs. SCE and 5.1 times the peak mass activity. In addition, Pt–MoP/C has also excellent stability and CO tolerance, including a peak mass activity retention of 81.4% after 1000 cycles as compared to that of 51.6% on commercial Pt/C and a 140 mV more negative CO_ad oxidation potential. The noteworthy promotion effect of MoP on Pt in methanol electrooxidation is also evaluated by theoretical calculations.