Plasmon-Mediated Solar Steam Generation over Au@Cu7S4 Yolk@Shell Nanocrystals

Abstract

In recent years, solar steam generation has attracted extensive attention because it can address the shortage of water resources. Traditional techniques enabling solar steam generation are based on heating water under concentrated solar irradiation, suffering from low solar to heat conversion efficiency. By exploiting the heat localization effect from photothermal materials, the efficiency of solar steam generation can be significantly improved. Similarly, electromagnetic field confinement induced by plasmonic materials has also proven efficient for promoting solar steam generation. In this study, Au@Cu7S4 yolk@shell nanocrystals were prepared and employed as plasmonic mediums for superior solar steam generation. Here, Au was a typical plasmonic metal showing a plasmon resonance peak around 550 nm. Cu7S4, on the other hand, represented a self-doped plasmonic semiconductor capable of absorbing photons beyond 1000 nm. The combination of Au and Cu7S4 in Au@Cu7S4 nanocrystals allowed a broadband light absorption across the visible and near infrared regions. The superior solar steam generation over Au@Cu7S4 was attributed to the broadband light absorption and the enhanced solar to heat conversion efficiency rendered by the combined plasmonic effects of Au and Cu7S4.