Atomic Au₃Cu Palisade Interlayer in Core@Shell Nanostructures for Efficient Kirkendall Effect Mediation

Plasmonic Cu@semiconductor heteronanocrystals (HNCs) have many favorable properties, but the synthesis of solid structures is often hindered by the nanoscale Kirkendall effect. Herein, we present the use of an atomically thin Au₃Cu palisade interlayer to reduce lattice mismatch and mediate the Kirkendall effect, enabling the successive topological synthesis of Cu@Au₃Cu@Ag, Cu@Au₃Cu@Ag₂S, and further transformed solid Cu@Au₃Cu@CdS core-shell HNCs via cation exchange. The atomically thin and intact Au₃Cu palisade interlayer effectively modulates the diffusion kinetics of Cu atoms as demonstrated by experimental and theoretical investigations and simultaneously alleviates the lattice mismatch between Cu and Ag as well as Cu and CdS. The Cu@Au₃Cu@CdS HNCs feature exceptional crystallinity and atomically organized heterointerfaces between the plasmonic metal and the semiconductor. This results in the efficient plasmon-induced injection of hot electrons from Cu@Au₃Cu into the CdS shell, enabling the Cu@Au₃Cu@CdS HNCs to achieve high activity and selectivity for the photocatalytic reduction of CO₂ to CO.