Plasmon-Enhanced Light Absorption Below the Bandgap of Semiconducting SnS Microcubes for Highly Efficient Solar Water Evaporation.

Semiconducting materials show high potential for solar energy harvesting due to their suitable bandgaps, which allow the efficient utilization of light energy larger than their bandgaps. However, the photon energy smaller than their bandgap is almost unused, which significantly limits their efficient applications. Herein, plasmonic Pd/SnS microcubes with abundant Pd nanoparticles attached to the SnS nanosheets are fabricated by an in situ photoreduction method. The as-prepared Pd/SnS microcubes extend the light-harvesting ability of SnS beyond its cutoff wavelength, which is attributed to the localized surface plasmon resonance (LSPR) effect of the Pd nanoparticles and the 3D structure of the SnS microcubes. Pd nanoparticles can also enhance the light absorption of TiO nanoparticles and NiPS nanosheets beyond their cutoff wavelengths, revealing the universality for promoting absorption above the cutoff wavelength of the semiconductors. When the plasmonic Pd/SnS microcubes are integrated into a hydrophilic sponge acting as the solar evaporator, a solar-to-vapor efficiency of up to 89.2% can be achieved under one sun. The high solar-to-vapor conversion efficiency and the broad applicability of extending the light absorption far beyond the cutoff wavelength of the semiconductor comprise the potential of innovative plasmonic nanoparticle/semiconductor composites for solar desalination.