A selenium-mediated layer-by-layer synthetic strategy for multilayered multicomponent nanocrystals

Ordered heterostructured nanocrystals with large compositional and morphological diversity are important for many applications. However, design of multicomponent nanostructures at the atomic level is difficult due to the elusive nucleation and growth processes in a solution-phase environment. Here we report a modular synthetic protocol that produces ordered multilayered nanostructures with small particle size by layer-by-layer growth. We introduce a selenium capping agent to hinder self-assembly, aggregation and phase segregation of nanostructures, while also sequencing the priority of metal atoms that migrate in the substrate lattice according to different metal–selenium bonding strengths, leading to a layer-by-layer growth for ordered nanostructures. The multilayered multicomponent nanocrystals are demonstrated in an alkaline polymer electrolyte fuel cell by using PtRuZn-SKE (SKE, selenium-mediated Kirkendall effect) as the anodic hydrogen oxidation reaction catalyst, which can deliver a high peak power density of 1.52 W cm⁻² in H₂–O₂ and 1.12 W cm⁻² in H₂–air (CO₂-free) while operating at 600 mA cm⁻² for 100 h. This generalizable strategy provides a predictable synthetic pathway to complex nanocrystals. 

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