A new magneto-optical phenomenon enhanced by Au nanoparticles on 3D Ni sub-microstructures.

We constructed a bio-structured surface-plasmonic/magneto-optic composite of ferromagnet metal Ni and noble metal Au. It was found that Ni Morpho menelaus (Mm) butterfly wings (BWs) with a natural photonic crystal structure have an apparent enhancement of light reflection under a 0.3 T magnetic field. Additional introduction of discrete Au particles helps further increase this magnetism-induced response. Compared with Mm-Ni-BWs, Mm-Ni-Au30-BWs' reflectance increases 5.3 times at 1944 nm. This investigation helps reveal and understand the effects of new micro-nanostructures on surface plasmon/magneto-optic coupling, benefiting future applications of biology sensors, chemical sensors, photonic chips, electrical communication systems, etc.

Biotemplated g-C3N4/Au Periodic Hierarchical Structures for the Enhancement of Photocatalytic CO2 Reduction with Localized Surface Plasmon Resonance.

Graphitic carbon nitride (g-C3N4) is a promising photocatalyst for CO2 reduction to alleviate the greenhouse effect. However, the low light absorption, small specific surface area, and rapid charge recombination limit the photocatalytic efficiency of g-C3N4. Herein, we demonstrate a bioinspired nanoarchitecturing strategy to significantly improve the light harvesting and charge separation of the g-C3N4/Au composite, as proven by the remarkable photocatalytic CO2 reduction. Specifically, a biotemplating approach is employed to transfer the sophisticated hierarchical structures and the related light-harvesting functionality of Troides helena butterfly wings to the g-C3N4/Au composite. The resulting g-C3N4/Au composite shows high photocatalytic efficiency under UV-visible excitation with triethanolamine as the sacrificial agent. The yields of CO and CH4 are 331.57 and 39.71 µmol/g/h, respectively, which are ∼36 times and ∼88 times that of pure g-C3N4 under the same conditions. Detailed experiments and the finite-difference time-domain method suggest that the superb photocatalytic activity should be ascribed to the unique periodic hierarchical structure which assists the light absorption and the localized surface plasmon resonance for promoted charge separation in addition to the more effective CO2 diffusion and larger specific surface area. Our work provides a new path for the design and optimization of photocatalysts based on biological structures that are usually unattainable artificially.

Conjugated Acetylenic Polymers Grafted Cuprous Oxide as an Efficient Z-Scheme Heterojunction for Photoelectrochemical Water Reduction.

As attractive materials for photoeletrochemical hydrogen evolution reaction (PEC HER), conjugated polymers (e.g., conjugated acetylenic polymers [CAPs]) still show poor PEC HER performance due to the associated serious recombination of photogenerated electrons and holes. Herein, taking advantage of the in situ conversion of nanocopper into Cu2 O on copper cellulose paper during catalyzing of the Glaser coupling reaction, a general strategy for the construction of a CAPs/Cu2 O Z-scheme heterojunction for PEC water reduction is demonstrated. The as-fabricated poly(2,5-diethynylthieno[3,2-b]thiophene) (pDET)/Cu2 O Z-scheme heterojunction exhibits a carrier separation efficiency of 16.1% at 0.3 V versus reversible hydrogen electrode (RHE), which is 6.7 and 1.4-times higher respectively than those for pDET and Cu2 O under AM 1.5G irradiation (100 mW cm-2 ) in the 0.1 m Na2 SO4 aqueous solution. Consequently, the photocurrent of the pDET/Cu2 O Z-scheme heterojunction reaches ≈520 µA cm-2 at 0.3 V versus RHE, which is much higher than pDET (≈80 µA cm-2 ), Cu2 O (≈100 µA cm-2 ), and the state-of-the-art cocatalyst-free organic or organic-semiconductor-based heterojunctions/homojunctions photocathodes (1-370 µA cm-2 ). This work advances the design of polymer-based Z-scheme heterojunctions and high-performance organic photoelectrodes.

A Scalable Nickel-Cellulose Hybrid Metamaterial with Broadband Light Absorption for Efficient Solar Distillation.

Sophisticated metastructures are usually required to broaden the inherently narrowband plasmonic absorption of light for applications such as solar desalination, photodetection, and thermoelectrics. Here, nonresonant nickel nanoparticles (diameters < 20 nm) are embedded into cellulose microfibers via a nanoconfinement effect, producing an intrinsically broadband metamaterial with 97.1% solar-weighted absorption. Interband transitions rather than plasmonic resonance dominate the optical absorption throughout the solar spectrum due to a high density of electronic states near the Fermi level of nickel. Field solar purification of sewage and seawater based on the metamaterial demonstrates high solar-to-water efficiencies of 47.9-65.8%. More importantly, the solution-processed metamaterial is mass-producible (1.8 × 0.3 m2 ), low-cost, flexible, and durable (even effective after 7 h boiling in water), which are critical to the commercialization of portable solar-desalination and domestic-water-purification devices. This work also broadens material choices beyond plasmonic metals for the light absorption in photothermal and photocatalytic applications.