Enhanced Electrocatalytic Activity of Ethanol Oxidation Reaction on Palladium–Silver Nanoparticles via Removable Surface Ligands

This work developed a facile colloidal route to synthesize BH₄^–-capped Pd_xAg_y nanoparticles (NPs) in water using the reducing ionic liquids of [C_nmim]­BH₄, and the resulting NPs were prone to form the nanocomposites with [amim]⁺-modified reduced graphene (RG). The removal of the metal-free inorganic ions of BH₄^– can create the profoundly exposed interfaces on the Pd_xAg_y NPs during the electrooxidation, and favor the ethanol oxidation reaction (EOR) in lowering energy barrier. The counterions of [C_nmim]⁺ can gather ethanol, OH^– ions, and the reaction intermediates on catalysts, and synergistically interact with RG to facilitate the charge transfer in nanocomposites. The interface-modified RG nanosheets can effectively segregate the Pd_xAg_y NPs from aggregation during the EOR. Along with the small size of 4.7 nm, the high alloying degree of 60.2%, the large electrochemical active surface area of 64.1 m² g^–1, and the great peak current density of 1501 mA cm^–2 mg^–1, Pd₁Ag₂@[C₂mim]­BH₄-amimRG nanocomposite exhibits the low oxidation potentials, strong poison resistance, and stable catalytic activity for EOR in alkaline media, and hence can be employed as a promising anodic catalyst in ethanol fuel cells.