Porous Pd-PdO Nanotubes for Methanol Electrooxidation

Palladium (Pd) nanostructures are highly active non-platinum anodic electrocatalysts in alkaline direct methanol fuel cells (ADMFCs) and their electrocatalytic performance relies highly on their morphology and composition. Herein, a facile high-temperature pyrolysis method to synthesize high-quality Pd-palladium oxide (PdO) porous nanotubes (PNTs) by using Pd(II)-dimethylglyoxime complex (Pd(II)-DMG) nanorods as a self-template is reported. The chemical component of pyrolysis products highly correlates with pyrolysis temperature. The electrochemical measurements and density functional theory calculations show the existence of PdO enhances the electroactivity of metallic Pd for both methanol oxidation reaction (MOR) and carbon monoxide oxidation reaction in alkaline media. Benefiting from its one-dimensionally porous architecture and evident synergistic effect between PdO and Pd (e.g., electronic effect and bifunctional mechanism), Pd-PdO PNTs achieve a 3.7-fold mass activity enhancement and improved durability for MOR compared to commercial Pd nanocrystals. Considering the simple synthesis, excellent activity, and long-term stability, Pd-PdO PNTs may be highly promising anodic electrocatalysts in ADMFCs.