Synthesis of magnetically separable Fe₃O₄-Au-CdS kinked heterotrimers incorporating plasmonic and semiconducting functionalities

Abstract

Dimension, composition and configuration are the primary aspects of semiconductor based hybrid heterostructures that govern their properties. To achieve desired functionalities within a single nanoparticle system, numerous synthetic approaches are available which may be suitable for achieving the target combination but these can be complex and tedious. In this work, a simple seeded-growth approach was employed to obtain an iron oxide–gold–cadmium sulfide (Fe₃O₄–Au–CdS) heterotrimer with a unique morphology manifesting magnetic, plasmonic and semiconducting properties. In a straightforward two-step synthesis process, Au–Fe₃O₄ dimer was injected as a seed into the Cd precursor solution for the growth of one-dimensional (1D) kinked CdS-5 nanorods on it. The synthesized Fe₃O₄–Au–CdS heterotrimer was tested in photocatalytic water-reduction reaction, revealing its potential as a photocatalyst for the hydrogen evolution reaction (HER), where each domain within the heterotrimer played a distinct role including light absorption, charge separation and magnetic separation. A post-synthetic modification on the semiconductor part was also performed where kinked CdS nanorod was cation exchanged with Ag₂S leading to the formation of another heterotrimer of Fe₃O₄–Au–Ag₂S while retaining the same morphology and expanding the palette of heterotrimers.