Plasmonic Cu₂₇S₂₄ nanocages for novel solar photothermal nanoink and nanofilm

Copper sulfide (Cu_xS) as a plasmonic solar photothermal semiconductor material that expands the light collection range by altering localized surface plasmon resonance (LSPR) to the near- to mid- infrared (IR) spectral region. The versatile synthesis strategies of Cu_xS nanostructure offer its variability of morphology and provide additional freedom in tuning the optical property. Particularly, nanocage (or nanoshell) has hybridized plasmon resonances as a result of super-positioned nanosphere and nanocavity, which extends its receiving range of solar spectrum and increases light-to-heat conversion rate. Here, we offer novel “nanoink” and “nanofilm” developed from colloidal Cu₂₇S₂₄ nanocages with excellent solar photothermal response. Via combining experimental measurement and theoretical calculation, we estimated the optical properties of covellite Cu₂₇S₂₄. And based on obtained dielectric functions, we then calculated its solar photothermal performance, which was further validated by our experimental measurement. The simulation results showed that hollow Cu₂₇S₂₄ nanocages have excellent solar photothermal performance, and exhibit much higher solar photothermal conversion efficiency than solid Cu₂₇S₂₄ nanospheres.