Morphology-controlled synthesis of Au/Cu₂FeSnS₄ core-shell nanostructures for plasmon-enhanced photocatalytic hydrogen generation

Copper-based chalcogenides of earth-abundant elements have recently arisen as an alternate material for solar energy conversion. Cu₂FeSnS₄ (CITS), a quaternary chalcogenide that has received relatively little attention, has the potential to be developed into a low-cost and environmentlly friendly material for photovoltaics and photocatalysis. Herein, we report, for the first time, the synthesis, characterization, and growth mechanism of novel Au/CITS core-shell nanostructures with controllable morphology. Precise manipulations in the core-shell dimensions are demonstrated to yield two distinct heterostructures with spherical and multipod gold nanoparticle (NP) cores (Au_sp/CITS and Au_mp/CITS). In photocatalytic hydrogen generation with as-synthesized Au/CITS NPs, the presence of Au cores inside the CITS shell resulted in higher hydrogen generation rates, which can be attributed to the surface plasmon resonance (SPR) effect. The Au_sp/CITS and Au_mp/CITS core-shell NPs enhanced the photocatalytic hydrogen generation by about 125% and 240%, respectively, compared to bare CITS NPs.