Aqueous Topological Synthesis of Au@semiconductor Core-Shell Nanocrystals with Morphology and Composition Engineering.

Core-shell nanocrystals (C-S NCs) are an essential class of materials whose structural engineering has attracted wide attention due to their tunable optical and electrical properties, especially noble metal@semiconductor (NMS) C-S NCs with flexible plasmon-exciton coupling. Due to their diverse critical applications, especially aqueous biological applications, herein we propose an aqueous topological strategy enabled by cation exchange reactions (CER) to synthesize various plasmonic Au@semiconductor C-S NCs, in which environmentally friendly triphenylphosphine (TPP) is used as an initiator instead of inflammable tributyl phosphine (TBP). The introduction of the milder, solid TPP facilitated a new aqueous CER strategy for synthesizing Au@semiconductor NCs with tailored chalcogenide compositions and morphologies. For example, the as-synthesized Au@ZnS C-S NRs had better absorption and biocompatibility and exhibited excellent photodynamic therapy efficacy.

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.