Synthesis of Free-Standing Alloyed PdSn Nanoparticles with Enhanced Catalytic Performance for Ethanol Electrooxidation

Alloyed Pd-based nanostructured materials have been demonstrated as highly active fuel cell anode electrocatalysts for the alcohol oxidation reaction. Challenges remain in the controlled synthesis of freestanding PdM alloys catalysts through optimization of their interfacial and surface structures, which can prevent degradation and poor durability. Herein, we present an oil-bath-based approach to synthesize PdxSny nanoparticles (NPs) with L-ascorbic acid (AA) as a reducing agent and cetyltrimethylammonium bromide as a structure-directing agent. PdxSny NPs (x/y=0.66, 0.83, and 1.11) show a particular freestanding shape. Among the three alloys, Pd20Sn24 (x/y=0.83) NPs have the best electrocatalytic activity (2018 mA mg(-1)) toward the ethanol oxidation reaction (EOR). The enhanced performance of PdxSny NPs might be attributed to i) a change in the electron structure of Pd, ii) varied interatomic distance within a unit cell, and iii) weak adsorption of in-situ generated oxygen-containing (e. g. *OH and Pd-O) or carbon-containing (e. g. *CH3CHOH, *CH3CHO, and *CH3CO) intermediate species. Experimental data proposed that higher catalytic temperature, higher pH values, and higher ethanol concentration should accelerate each step of electrooxidation of the EOR.