Surface-ligand protected reduction on plasmonic tuning of one- dimensional MoO_3-x nanobelts for solar steam generation

Sub-stoichiometric MoO_3-x nanostructures with plasmonic absorption via creating oxygen vacancies have attracted extensive attentions for many intriguing applications. However, the synthesis of one-dimensional (1D) plasmonic MoO_3-x nanostructures with widely tunable plasmonic absorption has remained a significant challenge because of their serious morphological destruction and phase change with increasing the concentration of oxygen vacancies. Here we demonstrate a surface-ligand protected reduction strategy for the synthesis of 1D MoO_3-x nanobelts with tunable plasmonic absorption in a wide wavelength range from 200 to 2,500 nm. Polyethylene glycol (PEG-400) is used as both the reductant to produce oxygen vacancies and the surface protected ligands to maintain 1D morphology during the formation process of MoO_3-x nanobelts, enabling the widely tunable plasmonic absorption. Owing to their broad plasmonic absorption and unique 1D nanostructure, we further demonstrate the application of 1D MoO_3-x nanobelts as photothermal film for interfacial solar evaporator. The surface-ligand protected reduction strategy provides a new avenue for the developing plasmonic semiconductor oxides with maintained particle morphology and thus enriching their wide applications.