Engineering ultrathin PdAu nanoring via a facile process for electrocatalytic ethanol oxidation

• Development of a facile process involving galvanic replacement reaction and oxidation etching reaction for the construction of ultrathin PdAu nanorings. • Precise controllability in elements ratios and compositions of ultrathin 2D nanorings. • Enhanced electrocatalytic EOR performance owing to synergistically structural and compositional advantages of PdAu nanorings. Ultrathin nanoframes with more available electrocatalytic active sites on both internal and external surfaces have attracted great attention especially in the field of electrocatalysis. Herein, we report a facile process to prepare PdAu nanorings (NRs) in aqueous solution without adding any organic ligands. The growth mechanism of PdAu NRs was explored in detail. The Au precursors were reduced into Au clusters around the edges of Pd nanosheets (NSs) via galvanic replacement, then the center of Pd NSs was oxidatively etched by Cl - /O 2 , and finally the Pd and Au atoms on the edge sites were rearranged to form uniform PdAu alloy. PdAu NRs with different ratios and ternary PdAuPt NRs could be easily prepared using this strategy. Owing to the synergistically structural and compositional advantages, Pd 79 Au 21 NRs exhibited higher electrocatalytic activity and stability, as well as low activation energy ( E a ) for the ethanol electrooxidation reaction.