Chemoselective Surface Trap-Mediated Metal Growth on Semiconductor Nanocrystals

We present a highly chemoselective deposition of precious metals on semiconductor nanoheterostructures with a strong preference for cadmium and zinc telluride over the lighter chalcogenides. The selectivity is explained by p-type surface traps on the tellurides, compared to n-type defects of the homologous sulfides and selenides, and can be turned off by passivating the particle surface. The results give insight into the nature and role of surface defects for semiconductor nanocrystals. The fast formation of many, small metal seeds leads to aggregation of the particles into star-shaped or branched superstructures, leaving the rest of the semiconductor surface exposed. It provides a preparative route toward complex, yet well-defined semiconductor-metal hybrid structures with potential application in photocatalysis.