A top-down synthesis of wurtzite Cu2SnS3 nanocrystals for efficient photoelectrochemical performance

Abstract

In this work, a top-down strategy to prepare metastable wurtzite Cu₂SnS₃ nanocrystals is reported for the first time. Wurtzite Cu₂SnS₃ nanocrystals with diameters of 7 ± 3 nm are synthesized by reacting Cu₂O nanocubes in a tin–metal chalcogenide complex (Sn–MCC) aqueous solution. A conversion process of cubic Cu₂O nanocubes → monoclinic Cu₇S₄ nanoboxes → hexagonal CuS nanoboxes → wurtzite Cu₂SnS₃ nanoboxes → wurtzite Cu₂SnS₃ nanocrystals is systematically investigated. It is revealed that formation of hollow nanoboxes is resulted from the Kirkendall effect while evolution from Cu₂SnS₃ nanoboxes to tiny Cu₂SnS₃ nanocrystals is due to an etching effect. Cu₂SnS₃ nanocrystal sensitized ZnO nanorod arrays are demonstrated as efficient photoanodes for photoelectrochemical (PEC) water splitting. Our work opens up a new door to prepare ecofriendly chalcogenide nanocrystals and for their promising applications in solar energy conversion devices.