Boosted light absorption by WO/Ag/PbS heterostructure for high-efficiency interfacial solar steam generation.

Interfacial solar steam generation is considered a promising approach to address energy and drinking water shortages. However, designing efficient light-absorbing and photothermal-converting materials remains challenging. In this study, we describe a detailed method for synthesising a three-dimensional (3D) hierarchical oxygen defect-rich WO/Ag/PbS/Ni foam (termed WO/Ag/PbS/NF) composite to realise efficient exciton separation and enhanced photothermal conversion. The 3D heterogeneous ternary photothermal material combines the individual benefits of WO, Ag and PbS, improving charge transfer and promoting photogenerated electron-hole pairs. This enhances light absorption and energy conversion. Theoretical calculations indicate that the increased photothermal conversion efficiency primarily results from the heterojunction between Ag, WO and PbS, facilitating exciton separation and electron transfer. Consequently, the WO/Ag/PbS/NF solar evaporator exhibits exceptional light absorption (98% within the sunlight spectrum), a high evaporation rate of 1.90 kg mh under 1 sun and a light-to-heat conversion efficiency of 94%. The WO/Ag/PbS/NF evaporator also exhibits excellent capabilities in seawater desalination and wastewater treatment. This approach introduces a synergistic concept for creating novel multifunctional light-absorbing materials suitable for various energy-related applications.