Pd Monolayer on the 3D-Hollow-Porous Au Microsphere as an Advanced Electrocatalyst for the Ethanol Oxidation Reaction

Pd is a highly active non-Pt anode in direct ethanol fuel cells, and its morphology and structural composition heavily influence its electrocatalytic efficiency. In this study, three-dimensional (3D)-hollow Au microspheres (HNPs-Au) as a support for the Pd monolayer (HNPs-Au@Pd) were synthesized using a simple template method and galvanic replacement reaction. The experimental results and theoretical calculations show that the presence of HNPs-Au enhances the catalytic activity of ethanol oxidation in alkaline media, improving the electroactivity of metallic Pd. Benefiting from the 3D-hollow-porous structure and the significant synergistic impact between Au and Pd (balancing the adsorption energy of the intermediate and reactant molecules), HNPs-Au@Pd achieves a 10.8-fold mass activity and a 3.3-fold enhancement of the specific activity for the ethanol oxidation reaction when compared to commercial Pd/C. The present work not only enriches the preparation strategy of porous metal materials but also opens up a sector for the construction of anodic electrocatalysts with a wide range of applications.