Nanophotonic materials for solar energy harvesting and photothermal conversion are urgently needed to alleviate the global energy crisis. We demonstrate that a broadband absorber made of tellurium (Te) nanoparticles with a wide size distribution can absorb more than 85% solar radiation in the entire spectrum. Temperature of the absorber irradiated by sunlight can increase from 29° to 85°C within 100 s. By dispersing Te nanoparticles into water, the water evaporation rate is improved by three times under solar radiation of 78.9 mW/cm². This photothermal conversion surpasses that of plasmonic or all-dielectric nanoparticles reported before. We also establish that the unique permittivity of Te is responsible for the high performance. The real part of permittivity experiences a transition from negative to positive in the ultraviolet-visible–near-infrared region, which endows Te nanoparticles with the plasmonic-like and all-dielectric duality. The total absorption covers the entire spectrum of solar radiation due to the enhancement by both plasmonic-like and Mie-type resonances. It is the first reported material that simultaneously has plasmonic-like and all-dielectric properties in the solar radiation region. These findings suggest that the Te nanoparticle can be expected to be an advanced photothermal conversion material for solar-enabled water evaporation.

Electromagnetically induced transparency is a type of quantum interference that induces near-zero reflection and near-perfect transmission. As a classical analogy, metal nanostructure plasmonic ‘molecules’ produce plasmon-induced transparency conventionally. Herein, an electromagnetically induced transparency interaction is demonstrated in silicon nanosphere oligomers, wherein the strong magnetic resonance couples with the electric gap mode effectively to markedly suppress reflection. As a result, a narrow-band transparency window created at visible wavelengths, called magnetically induced transparency, is easily realized in nearly touching silicon nanospheres, exhibiting low dependence on the number of spheres and aggregate states compared with plasmon induced transparency. A hybridization mechanism between magnetic and electric modes is proposed to pursue the physical origin, which is crucial to build all-dielectric metamaterials. Remarkably, magnetic induced transparency effect exhibiting near-zero reflection and near-perfect transmission causes light to propagate with no extra phase change. This makes silicon nanosphere oligomers promising as a unit cell in epsilon-near-zero metamaterials.

Among numerous visible-light photocatalysts, plasmonic structure is a promising photocatalyst for photodegradation and energy generation. Ag/AgCl composite as an alternative visible-light photocatalyst has attracted extensive interests; however, its syntheses has many visible flaws, e.g. high temperature environment, requirement of various templates or additives, complicated synthetic procedures and impurities in the final products. For these issues, herein, we report, for the first time, a simple, facile, rapid and green technique to synthesize Ag/AgCl heterostructured cubes using a one-step process of laser irradiation in liquids. The fabricated Ag/AgCl cubes possess some active {111} facets and a high visible-light utilization efficiency induced by the localized surface plasmon resonance (SPR) from the Ag/AgCl heterostructure. As plasmonic photocatalysts, these Ag/AgCl cubes exhibited excellent photodegrading performance for dye molecules of methyl orange, Rhodamine B and methylene blue, and the photodegradation rates were about 0.268, 0.057, and 0.094 min⁻¹, which are considerably higher than that of commercial Ag₃PO₄ by a factor of 29.8, 3.8 and 6.7, respectively. The high photo-stability of the Ag/AgCl cubes was also demonstrated. The SPR-mediated photocatalytic mechanism was proposed to address the ultrahigh activity of the Ag/AgCl heterostructure as an advanced visible-light photocatalyst. These results showed the broad applicability of the developed technique for accessing a new plasmonic photocatalyst with high-performance.