Electronic and Coordination Effect of PtPd Nanoflower Alloys for the Methanol Electrooxidation Reaction

Abstract

Platinum-based electrocatalysts usually exhibit limited and quickly vanished activity for the methanol oxidation reaction (MOR) due to active site occupation and surface intermediate poisoning, especially CO. The attendant synergistic effect of the alloy strategy is often executed to improve these flaws. Here, PtPd nanoflower alloys uniformly anchored on the carbon paper were successfully synthesized by electrodeposition to construct well-defined active sites, over which high MOR activity and tolerance were realized. The homogeneous alloy structure of PtPd nanoflowers was confirmed by TEM and XAFS. Impressively, the Pt1Pd1-N NFs/CP exhibited an excellent mass activity of 9.25 A mgPt+Pd–1 and specific activity of 13.2 mA cmECSA–2 of MOR in the alkaline electrolyte, and 87.8% of the initial activity was still retained after 500 cycles. In situ infrared spectroscopy revealed that Pt1Pd1-N NFs/CP ensured the complete oxidation of methanol following a CO-free path. The investigation of the electronic and coordination structure demonstrated that the Pt–Pd adjacent sites with a zero valence are the highly active center for MOR, and the synergistic effect between Pt and Pd greatly improved the MOR electrocatalytic performance. This work offers an effective strategy to precisely control the number and structure of decorating species for constructing alloy nanocatalysts to enhance the electroactivity toward MOR.