Twin-boundary-rich PtPd metallene suppresses CO poisoning for efficient methanol electrooxidation

An ultrathin two-dimensional twin-boundary-rich PtPd metallene (TB-PtPdene) was successfully synthesized by salt templating. • Pt-Pd alloying and twin interfaces optimize the adsorption energetics of intermediate products. • TB-PtPdene reaches 1.99 A mg PGM −1 for methanol electrooxidation and maintains stability for 800 h. • In situ FTIR and DFT reveal suppressed CO poisoning on TB-PtPdene. • TB-PtPdene enables direct methanol fuel cells with 14.2 mW cm −2 peak power density. Direct methanol fuel cells (DMFCs) are regarded as a highly promising clean-energy technology. Herein, an ultrathin two-dimensional twin-boundary-rich PtPd metallene (TB-PtPdene) is successfully synthesized using a salt-templating method. Structural analyses confirm a homogeneous metallic alloy configuration with reduced coordination environments and optimized electronic structure induced by twin interfaces. Electrochemical evaluations show that TB-PtPdene delivers a mass activity of 1.99 A mg PGM −1 , outperforming commercial Pt black, Pd black, and TB-Ptene for methanol oxidation reaction (MOR). Mechanistic studies reveal suppressed accumulation of poisoning CO intermediates and altered behavior of oxygenated intermediates on TB-PtPdene. Density functional theory calculations further reveal that the twin-boundary-rich PtPd structure modulates the adsorption energetics of MOR intermediates and reduces the uphill free-energy change of the *CHO-to-*HCOO step. TB-PtPdene also maintains substantial catalytic activity during prolonged electrochemical operation, with its structural integrity well preserved after stability testing. When TB-PtPdene is implemented in DMFCs, the assembled device achieves a peak power density of 14.2 mW cm −2 , significantly exceeding that of Pt black-based devices. This work offers an innovative strategy for designing MOR electrocatalysts with both high activity and stability, and deepens the mechanistic understanding of the role of twin defects in catalytic processes. Download: Download high-res image (258KB) Download: Download full-size image