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An ideal solar-thermal absorber requires efficient selective absorption with a tunable bandwidth, excellent thermal conductivity and stability, and a simple structure for effective solar thermal energy conversion. Despite various solar absorbers having been demonstrated, these conditions are challenging to achieve simultaneously using conventional materials and structures. Here, we propose and demonstrate three-dimensional structured graphene metamaterial (SGM) that takes advantages of wavelength selectivity from metallic trenchlike structures and broadband dispersionless nature and excellent thermal conductivity from the ultrathin graphene metamaterial film. The SGM absorbers exhibit superior solar selective and omnidirectional absorption, flexible tunability of wavelength selective absorption, excellent photothermal performance, and high thermal stability. Impressive solar-to-thermal conversion efficiency of 90.1% and solar-to-vapor efficiency of 96.2% have been achieved. These superior properties of the SGM absorber suggest it has a great potential for practical applications of solar thermal energy harvesting and manipulation.

Although the concept of using local surface plasmon resonance based nanoantenna for photodetection well below the semiconductor band edge has been demonstrated previously, the nature of local surface plasmon resonance based devices cannot meet many requirements of photodetection applications. Here we propose the concept of deep-trench/thinmetal (DTTM) active antenna that take advantage of surface plasmon resonance phenomena, three-dimensional cavity effects, and large-area metal/semiconductor junctions to effectively generate and collect hot electrons arising from plasmon decay and, thereby, increase photocurrent. The DTTM-based devices exhibited superior photoelectron conversion ability and high degrees of detection linearity under infrared light of both low and high intensity. Therefore, these DTTM-based devices have the attractive properties of high responsivity, extremely low power consumption, and polarization-insensitive detection over a broad bandwidth, suggesting great potential for use in photodetection and on-chip Si photonics in many applications of telecommunication fields.

Integrating multifunctional nanostructures capable of radiotherapy and photothermal ablation is an emerging alternative in killing cancer cells. In this work, we report a novel plasmonic heterostructure formed by decorating AuPt nanoparticles (NPs) onto the surfaces of CuS nanosheets (AuPt@CuS NSs) as a highly effective nanotheranostic toward dual-modal photoacoustic/computed tomography imaging and enhanced synergistic radiophotothermal therapy. These heterostructures can confer higher photothermal conversion efficiency via the local electromagnetic enhancement as well as a greater radiation dose deposition in the form of glutathione depletion and reactive oxygen species generation. As a result, the depth of tissue penetration is improved, and hypoxia of the tumor microenvironment is alleviated. With synergistic enhancement in the efficacy of photothermal ablation and radiotherapy, the tumor can be eliminated without later recurrence. It is believed that these multifunctional heterostructures will play a vital role in future oncotherapy with the enhanced synergistic effects of radiotherapy and photothermal ablation under the guided imaging of a potential dual-modality system.

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In this study, we combine graphene with gold oxide (AuOx), a transparent and high-work-function electrode material, to achieve a high-efficient, low-bias, large-area, flexible, transparent, broadband, and bifacial-operable photodetector. The photodetector operates through hot electrons being generated in the graphene and charge separation occurring at the AuOx-graphene heterojunction. The large-area graphene covering the AuOx electrode efficiently prevented reduction of its surface; it also acted as a square-centimeter-scale active area for light harvesting and photodetection. Our graphene/AuOx photodetector displays high responsivity under low-intensity light illumination, demonstrating picowatt sensitivity in the ultraviolet regime and nanowatt sensitivity in the infrared regime for optical telecommunication. In addition, this photodetector not only exhibited broadband (from UV to IR) high responsivity-3300 A W(-1) at 310 nm (UV), 58 A W(-1) at 500 nm (visible), and 9 A W(-1) at 1550 nm (IR)-but also required only a low applied bias (0.1 V). The hot-carrier-assisted photoresponse was excellent, especially in the short-wavelength regime. In addition, the graphene/AuOx photodetector exhibited great flexibility and stability. Moreover, such vertical heterojunction-based graphene/AuOx photodetectors should be compatible with other transparent optoelectronic devices, suggesting applications in flexible and wearable optoelectronic technologies.

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In this Article, we present a facile approach for the preparation of ecofriendly substrates, based on common rose petals, for ultrasensitive surface-enhanced Raman scattering (SERS). The hydrophobic concentrating effect of the rose petals allows us to concentrate metal nanoparticle (NP) aggregates and analytes onto their surfaces. From a systematic investigation of the SERS performance when using upper and lower epidermises as substrates, we find that the lower epidermis, with its quasi-three-dimensional (quasi-3D) nanofold structure, is the superior biotemplate for SERS applications. The metal NPs and analytes are both closely packed in the quasi-3D structure of the lower epidermis, thereby enhancing the Raman signals dramatically within the depth of focus (DOF) of the Raman optical system. We have also found the effect of the pigment of the petals on the SERS performance. With the novel petal-based substrate, the SERS measurements reveal a detection limit for rhodamine 6G below the femtomolar regime (10(-15) M), with high reproducibility. Moreover, when we employ an upside-down drying process, the unique effect of the Wenzal state of the hydrophobic petal surface further concentrate the analytes and enhanced the SERS signals. Rose petals are green, natural materials that appear to have great potential for use in biosensors and biophotonics.