Metal@I₂-II-IV-VI₄ core-shell nanocrystals: Controlled synthesis by aqueous cation exchange for efficient photoelectrochemical hydrogen generation

Multinary chalcogenide semiconductors (MCSs) recently emerged as a promising alternative to their binary counterparts for designing innovative solar energy conversion platforms due to a number of advantages including high absorption coefficient over a broad spectral range, conveniently tunable band structures through alloying, and nontoxicity for their use in real-world settings. The integration of MCSs with plasmonic metals into heteronanostructures is essential for promoting their light harvesting and conversion performance; however it is constrained by the large synthetic impediment arising from the incompatible activities of multiple precursors involved in growing the MCS domain via direct synthesis. Here using Au@Ag₂ZnSnS₄ core-shell nanocrystals (NCs) as a proof-of-concept demonstration, we report a new synthetic tactic based on cation exchange to access metal@MCS hybrid NCs with exceptional uniformity and precise control over the structural characteristics (both dimensions and morphology) in an aqueous environment. The prepared materials were explored as photoanodes for photoelectrochemical (PEC) hydrogen evolution, and the results suggested that our approach offers a good opportunity to unravel the delicate links between solar energy conversion efficiency and the structure of metal@MCS NCs. In view of the great versatility of cation exchange, we envision that this approach can be extended to fabricate a wide variety of metal@MCS NCs with unprecedented structures and functions.