https://phys.org/news/2019-01-nanostructures-harvesting-sunlight-solar-steam.html

Plasmonic metal nanostructures are a popular new material for many photonics applications, including solar cells and optical imaging, since they interact with light in unique ways and can be engineered to exhibit desirable properties. For solar steam generation, for example, they can be modified to have high light absorption and low scattering properties.

One limitation, however, is that plasmonic nanostructures have a narrow resonant band and so they can absorb only a small portion of the solar spectrum. In the new study, the researchers' main result was greatly expanding the narrow resonant band of the plasmonic silver nanoparticles.