Rational one-step synthesis of porous PtAg nanowires for methanol oxidation with a CO-poisoning tolerance: An experimental and theoretical study

Abstract

Binary Pt-based porous nanowires (PNWs) are highly promising for electrochemical applications owing to their high surface areas, abundant active sites, and immense durability against aggregation, but their simple template-free synthesis for methanol oxidation reaction (MOR) is rarely reported. Herein, we provide a simple and template-free method for the one-step fabrication of PtAgx PNWs via autocatalytic and oriented attachment growth mechanism in an autoclave. This drives the formation of ultra-long PtAg PNWs (∼1.5 µm length and 20 nm width) with agglutinated pores (2–10 nm), high Ag content (22–34 wt%), and upshifted d-band center. These merits endowed the methanol oxidation reaction (MOR) mass activity of PtAg PNWs (2.22 mA/µgPt) by 2.4 and 3.4 times than those of Pt PNWs and commercial Pt/C catalyst, respectively, based on equivalent Pt mass besides a superior stability and CO-poisoning tolerance. The MOR activity of PtAg PNWs outperformed previously reported PtAg nanostructures. Density functional theory (DFT) simulations confirmed the bifunctional MOR mechanism with a lower energy barrier for dissociative adsorption of methanol molecules (0.49 eV) and CO oxidation on PtAg PNWs than Pt PNWs. This study may allow the formation of Pt-based PNWs alloys with various metals for MOR.