Photogenerated carrier separation and localized surface plasmon resonance in SnS₂@AuNPs Janus heterostructures for enhanced visible light catalysis

We compare the visible light extinction difference of Janus and core-shell structures for several typical semiconductors and gold nanoparticles (AuNPs) and found out better extinction behavior of the Janus type with visible light response for narrow bandgap semiconductors. Following the predictions, we designed and prepared the Janus and core-shell heterostructures of SnS₂ (Eg = 2.1–2.4 eV) and AuNPs (SnS₂@AuNPs). Excellent visible light catalytic performance in Janus structures compared with SnS₂ and the core-shell structures can be observed, which was attributed to the enhanced localized surface plasmon resonance (LSPR) and the increased lifetime of photo generated carriers. The absorption spectrum revealed more significant LSPR intensities for the Janus structures compared to SnS₂ and the core-shell structures. The Photoluminescence (PL) spectrum of the core-shell and Janus structures showed a half and a quarter the intensities of the SnS₂. The shorter lifetime in Janus structures (1.16 ns) may result from the fast depopulation of photo-generated electrons from SnS₂ into Au. Due to the LSPR enhancement and the photo generated carriers separation in the Janus structures, the visible light catalytic performance of SnS₂ has been improved effectively.