High-quality ultralong copper sulphide nanowires for promising applications in high efficiency solar water evaporation

Abstract

Copper sulphide, with low cost and intrinsic near infrared (NIR) absorption, is an emerging and promising photothermal material that can provide high NIR photothermal conversion efficiency. Herein, we have successfully synthesized high-quality ultralong Cu_2−xS nanowires (NWs) with an average diameter of ∼50 nm and length up to tens of micrometers. The synthetic strategy is based on the colloidal hot injection of precursors in a high-boiling solvent and in the presence of surfactant molecules that guide the nanowire growth. The as-harvested ultralong Cu_2−xS NWs exhibit strong optical absorption in the NIR region and superior photothermal performance for solar water evaporation, yielding a solar thermal conversion efficiency of 89.9% under 8 kW m⁻² solar illumination. Meanwhile, the theoretical calculation of the band structure reveals that the ultralong Cu_2−xS NWs are hole-doped semiconductors with localized surface plasmon resonance (LSPR) from collective oscillation.