Concave cubic PtLa alloy nanocrystals with high-index facets: Controllable synthesis in deep eutectic solvents and their superior electrocatalytic properties for ethanol oxidation

Due to their strong electronic interactions and excellent electrochemical properties, noble metal-based rare earth nanoalloys are considered to be promising electrocatalytic materials for fuel cell applications. However, due to the limitation of the very negative reduction potential for rare earth metals, the wet chemical or electrochemical preparation of noble metal/rare earth nanoalloys is still challenging. Herein, we report a novel and effective strategy for the electrochemical synthesis in deep eutectic solvents of concave cubic PtLa alloy nanocrystals with high-index facets and superior electrocatalytic properties for the ethanol oxidation reaction. Scanning electron microscopy and transmission electron microscopy characterizations confirm that the concave cubic PtLa alloy nanocrystals of approximately 47.5 nm in size are uniformly electro-deposited on the glassy carbon substrate in deep eutectic solvents and are bounded with the {410} and adjacent high-index facets. X-ray photoelectron spectroscopy analysis indicates the presence of strong charge transfer interactions from La to Pt atoms in the concave cubic PtLa alloy nanocrystals. Due to the synergetic effect of the high-index facets and the charge transfer interactions between Pt and La, the synthesized concave cubic PtLa alloy nanocrystals exhibit enhanced specific current activity and long-term durability for the ethanol oxidation reaction.