Facile Synthesis of Pd and PdPtNi Trimetallic Nanosheets as Enhanced Oxygen Reduction Electrocatalysts

While bimetallic 2D metallic nanomaterials are widely synthesized and used as electrocatalysts with enhanced performance, trimetallic 2D structures are less commonly reported. In this work, a facile wet chemical method for synthesizing Pd nanosheets and PdPtNi trimetallic alloy nanosheets is developed. Without the introduction of gaseous CO and pressurized equipment, Pd nanosheets with a thickness of approximate to 2.85 nm and sizes in the range of 1-2 mu m can be obtained. The facile synthesis conditions allow for a comprehensive study of the nanosheet growth mechanism. It is found that 2D growth is closely related to the product of solvent decomposition and the additive ligand diethylenetriamine. Further, by depositing Pt and Ni onto the Pd nanosheets, trimetallic nanosheets with tunable compositions can be obtained and applied as oxygen reduction reaction electrocatalysts. Typically, the Pd9Pt1Ni1 nanosheets have the highest half-wave potential of 0.928 V (vs reversible hydrogen electrode), which is 34 mV higher than that of commercial Pt/C and 28 mV higher than that of Pd/C, and also have high durability.