Electronic effect on oxidation of formic acid on supported Pd–Cu bimetallic surface

Vapor deposition method is used to prepare layered Pd–Cu bimetallic model catalytic surfaces, with different thickness of Pd, supported on glassy carbon. Charge transfer from Pd to Cu produces a positive binding energy (BE) shift for the overlayer Pd 3d and an opposite shift for Cu 2p as measured by X-ray photoelectron spectroscopy (XPS). Similarly, the d-band center moves away from the Fermi level as the thickness of Pd decreased for these bimetallic materials. This electronic perturbation of the Pd–Cu systems results in a drastic increase in current density and an improved stability for formic acid electro-oxidation. Our findings indicate that layered Pd–Cu bimetallic surfaces with Pd layers thicker than 1 nm do not form a surface alloy at room temperature and are better electrocatalytic materials than Bulk Pd and could be used to enhance direct formic acid fuel cell (DFAFC) performance.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pd–Cu bimetallic model surface was prepared by vapor deposition method. ► XPS and d-band center values showed that electrons transfer from Pd to Cu layer. ► Both activity and stability of Pd–Cu for formic acid electro-oxidation were tested. ► Pd–Cu surface showed improved electrochemical performances than pure Pd surface.