Constructing poison-resistant Au-Pd single-atom alloy electrocatalyst on Pd nanocrystals for formic acid electrooxidation

Abstract

Pd is a promising anodic catalyst for direct formic acid fuel cells, while its performance on formic acid electrooxidation is still suffered from for low catalytic efficiency and durability. In this work, an electrochemical self-catalyzed method was employed to deposit Au single-atoms onto Pd nanocrystals with tuneable compositions. Spherical-corrected Scanning transmission microscope and electrochemical characteristics demonstrated that the Au atoms were atomic-dispersive on Pd nanocrystals, forming Au-Pd single-atom alloy. Systematic studies showed that the activity of Pdx @Auy/C SAA is related to the density of the Au single-atoms on Pd surface. When an optimized balance between active-site exposure and intrinsic activity is achieved, the Pd50 @Au1/C SAA showed superb formic acid electrooxidation activity of 4.98 A mg−1M and unusual high anti-poisoning ability which is distinctly different from most of the Pd based catalysts. The boosted electrochemical performances of Pdx @Auy/C SAA can be attributed to the unique geometric effect that facilitates the direct reaction route and favourable electronic effect that weakens the CO adsorption to Pd sites.