Silver Tipping of CdSe@CdS Nanorods: How To Avoid Cation Exchange

Cadmium chalcogenides-metal hybrid nanostructures play an important role in a wide range of applications and are key components in photocatalysis. Hence, great efforts have been devoted to the exploration of a variety of metal components, each offering different functionalities. Silver is a vital catalyst used in the production of major industrial chemicals, found in virtually every electronic device, widely exploited as an antibacterial agent, used in fuel cells, and has been extensively investigated for CO2 reduction. Yet, silver nanoparticles were not utilized in conjunction with cadmium chalcogenide colloidal nanostructures due to the tendency of Ag+ to undergo cation exchange. We present here a new strategy that opens up a pathway for avoiding cation exchange and obtaining metallic silver tipping on cadmium chalcogenide nanorods. The formation of Ag trioctylphosphine complex, as an intermediate in the course of Ag deposition on nanorods, was identified to be a critical step, which prevents undesirable cation exchange. Metallic Ag was confirmed by several advanced techniques and its growth location on the tip of nanorods was carefully studied. Moderate control over the crystalline Ag tip size was demonstrated in the range of 1.5-5.4 nm.